Aims: Arterial stiffness increases with both advancing age and chronic kidney disease (CKD) and may contribute to kidney function decline, but evidence is inconsistent. We hypothesized that greater baseline arterial stiffness (assessed as pulse pressure (PP) and carotid-femoral pulse-wave velocity CFPWV)) was independently associated with kidney disease progression over the follow-up period (3.8 years) in the Systolic Blood Pressure Intervention Trial (SPRINT). Materials and methods: 8,815 SPRINT participants were included in the analysis of PP. 592 adults who participated in a SPRINT ancillary study that measured CFPWV were included in subgroup analyses. Cox proportional hazards analysis was used to examine the association between PP and time to kidney disease progression endpoints: (A) incident estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m2 in non-CKD participants at baseline; (B) 50% decline in eGFR, initiation of dialysis, or transplant in those with baseline CKD. Mixed model analyses examined the association of baseline PP/CFPWV with follow-up eGFR. Results and conclusion: Mean ± SD age was 68 ± 10 years, baseline PP was 62 ± 14 mmHg, and CFPWV was 10.8 ± 2.7 m/s. In the fully adjusted model, PP ≥ median was associated with an increased hazard of kidney disease progression endpoints (HR: 1.93 (1.43 – 2.61)). The association remained significant in individuals without (2.05 (1.47 – 2.87)) but not with baseline CKD (1.28 (0.55 – 2.65)). In fully adjusted models, higher baseline PP associated with eGFR decline ), but baseline CFPWV did not. Among older adults at high risk for cardiovascular events, baseline PP was associated with kidney disease progression.  Arterial stiffness increases both with advancing age , 2 and a2) [Evidence whether increased arterial stiffness is associated either cross-sectionally with kidney function , 11 or l2) , 13 and 2) , 15 in s2)  and anal2) . Evidenc2) , 21, 22.Accordingly, the purpose of the present study was to test the hypothesis that greater baseline arterial stiffness was independently associated with decline in kidney function over the follow-up period in older adults without baseline diabetes mellitus who participated in the recently completed Systolic Blood Pressure Intervention Trial (SPRINT). We hypothesized that greater baseline arterial stiffness, as measured in the entire cohort by pulse pressure (PP)   and by cSPRINT was a multi-center, randomized, controlled trial in adults at high risk for cardiovascular events comparing standard (target systolic blood pressure (SBP) of < 140 mmHg) to intensive (target SBP of < 120 mmHg) blood pressure control, with a primary composite endpoint of myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes, as described previously , 26. The2 using the four-variable Modification of Diet in Renal Disease (MDRD) Study equation [For the present analysis, participants were classified based on the presence or absence of baseline CKD, defined in SPRINT as a baseline eGFR < 60 mL/min/1.73mequation . Of the 652 SPRINT participants from 11 clinical sites enrolled in an ancillary study that measured CFPWV, as described in detail previously . Due to All participants provided written informed consent. This study was approved by the investigational review boards at the participating centers and was conducted in adherence with the Declaration of Helsinki. Exposure variables PP, a surrogate of arterial stiffness , was calCFPWV was measured using the SphygmoCor CPV system device with software version 9.0  following a standard protocol, as described in detail previously . Outcome variables 2 (baseline CKD), the kidney disease progression endpoint was a composite of decrease in the eGFR of 50% or more (confirmed by a subsequent laboratory test at least 90 days apart) or the development of end-stage renal disease (ESRD) requiring long-term dialysis or kidney transplantation, as defined previously in the SPRINT study [2  [2 [In analyses where PP was the predictor, the primary outcome was time to achieve a kidney disease progression endpoint. For participants with baseline eGFR < 60 mL/min/1.73mNT study . The nonaseline) . The kidline) [2 . In analyses where CFPWV was the predictor, eGFR over time was the outcome variable, using a random intercept, random slope mixed model analysis using all available eGFR measurements. This analysis was also performed as a secondary endpoint with PP as the predictor variable. Covariates and stratification variable Baseline characteristics potentially related to arterial stiffness and kidney function decline, all measured at baseline, were selected a priori as covariates for this analysis. Baseline questionnaires and interviews were administered by trained clinical staff. Race and smoking status were determined by self-report. History of cardiovascular disease (CVD) and heart failure were determined by a detailed medical history collected at screening , 26. 2. Urinary ACR was calculated as urinary albumin/urinary creatinine (mg/g), using a spot urine. Number of anti-hypertensive agents at baseline (prior to randomization) was determined as described previously [Body-mass index (BMI) was calculated as weight in kilograms divided by height in meviously . The association of baseline PP and kidney disease progression endpoints was analyzed using Cox proportional hazards analysis. PP was considered as both a continuous variable as well as dichotomized as above and below the median PP. The association between CFPWV (dichotomized by median baseline CFPWV) and change in eGFR over time (interaction of baseline CFPWV × time as a predictor) was analyzed using a mixed model with random intercept and random slopes incorporating all available measurements of eGFR. Natural log-transformed eGFR values were used in these analyses. In each analysis, the initial model was unadjusted, with subsequent multivariable models adjusting for age, sex, race, and randomized treatment arm (model 1), model 1 plus CVD, heart failure, smoking, BMI, baseline eGFR (except for mixed model), and urinary ACR (model 2), and model 2 plus number of antihypertensive agents at baseline (model 3). Finally, mean arterial pressure (MAP) and heart rate were added (model 4). Of note, PP and MAP and were weakly correlated, thus unlikely to be collinear. We also evaluated the interaction of PP with sex and race. It was decided a priori to perform stratified analyses according to CKD and non-CKD groups regardless of the interaction term, as kidney disease progression may differ in individuals with and without baseline CKD. As a secondary analysis, the association between PP (dichotomized by median baseline PP) and change in eGFR over time (interaction of baseline PP × time as a predictor) was analyzed using a mixed model with random intercept and random slopes incorporating all available measurements of eGFR. Natural log-transformed eGFR values were used in these analyses. 2-test for categorical data and an independent samples t-test for continuous variables. Non-normally distributed variables were log-transformed (urinary ACR) or compared between groups using the Wilcoxon rank sum nonparametric test (eGFR slope). Two-tailed values of p < 0.05 were considered statistically significant for all analyses. All statistical analyses were performed using SAS version 9.4. Indices of kidney function decline and covariates at baseline were summarized above and below the median PP/CFPWV, and are presented as mean (standard deviation) or median (interquartile range) for continuous variables and n (%) for categorical variables. Comparisons between PP/CFPWV groups were made using a χ2. Individuals with a higher PP were more likely to be older, female, White, have prevalent CVD, heart failure, and CKD, have higher MAP and urinary ACR, have a lower baseline BMI, eGFR and heart rate, use more antihypertensive agents, and less likely to smoke  were White. The mean PP was 62 ± 14 mmHg, and mean baseline eGFR was 72 ± 21 mL/min/1.73mto smoke . The basIn both unadjusted and adjusted analyses, higher PP  was associated with an increased hazard of a kidney disease progression endpoint compared to the reference group  in all participants  Figure . This as591 SPRINT PWV ancillary study participants were included in the cross-sectional analysis with CFPWV as the predictor variable. Among these participants, the mean ± SD age was 72 ± 10 years, and 67% were White. Individuals with a higher CFPWV were more likely to be older and have a higher MAP . The meaIn fully adjusted analyses (model 4) including all participants, higher CFPWV was not associated with decline in eGFR, incorporating all available time points where eGFR was measured (baseline CFPWV × time interaction p = 0.34). Compared to baseline CFPWV above the median, annual change in lneGFR in individuals with baseline CFPWV below the median was 0.005  (model 4). Stratified analyses were performed, as decided a priori, according to CKD and non-CKD groups. The association remained non-significant in individuals with and without baseline CKD. Compared to baseline CFPWV above the median, annual change in lneGFR in individuals with baseline CFPWV below the median in individuals with baseline CKD was 0.0020 (–0.009 to 0.013) (baseline CFPWV × time interaction p = 0.72) (model 4). Compared to baseline CFPWV above the median, annual change in lneGFR in individuals without baseline CFPWV below the median in individuals without baseline CKD was 0.011 (–0.009 to 0.030) (baseline CFPWV × time interaction p = 0.28) (model 4). As a secondary endpoint, we also considered the association of PP with change in eGFR over time. PP was associated with a greater decline in eGFR, in the entire cohort in the fully adjusted model . Compared to baseline PP below the median, annual change in lneGFR in individuals with baseline PP above the median was –0.011 (–0.014 to –0.009). Again, stratified analyses were performed, as decided a priori, according to CKD and non-CKD groups. In individuals with baseline CKD, compared to baseline PP below the median, annual change in lneGFR in individuals with baseline PP above the median was –0.014 (–0.020 to –0.009) (baseline PP × time interaction p < 0.0001) (model 4). In individuals without baseline CKD, compared to baseline PP below the median, annual change in lneGFR in individuals with baseline PP above the median was –0.010 (–0.013 to –0.008) (baseline PP × time interaction p < 0.0001) (model 4). In older individuals with hypertension and at high risk for cardiovascular events, higher arterial stiffness, as measured by PP, was associated with an increased hazard of a kidney disease progression over a median follow-up of 3.8 years. This association was significant in individuals without baseline CKD, but not in those with baseline CKD. Of note, the sample size and number of events was smaller for the CKD group. However, both individuals with and without baseline CKD demonstrated an association of higher baseline PP with decline in eGFR over time. In contrast, we failed to demonstrate an association using the gold-standard measurement of CFPWV as the index of arterial stiffness; notably, the sample size was much smaller in this ancillary study. Evidence to date regarding the association of arterial stiffness with kidney function and subsequent decline in kidney function has been inconsistent. In cohorts of community-based adults, arterial stiffness (measured by CFPWV or PP), has been both independently associated  and not 2) in non-CKD participants at baseline, and either a 50% decline in eGFR, initiation of dialysis, or transplant in participants with CKD at baseline. There was a significant interaction term between PP and baseline CKD status in this analysis, such that an association remained for individuals without but not with baseline CKD. However, when change in eGFR over time was considered as a secondary endpoint, the association of PP with this endpoint was significant in both individuals with and without baseline CKD. In participants in the SPRINT study, we found an independent association of greater baseline PP with kidney disease progression endpoints, defined as incident CKD  from Takeda Pharmaceuticals International, Inc. All components of the SPRINT study protocol were designed and implemented by the investigators. The investigative team collected, analyzed, and interpreted the data. All aspects of manuscript writing and revision were carried out by the coauthors. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, the U.S. Department of Veterans Affairs, or the United States Government. For a full list of contributors to SPRINT, please see the supplementary acknowledgement list: The Systolic Blood Pressure Intervention Trial is funded with Federal funds from the National Institutes of Health (NIH), including the National Heart, Lung, and Blood Institute (NHLBI), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the National Institute on Aging (NIA), and the National Institute of Neurological Disorders and Stroke (NINDS), under Contract Numbers HHSN268200900040C, HHSN268200900046C, HHSN268200900047C, HHSN268200900048C, HHSN268200900049C, and Inter-Agency Agreement Number A-HL-13-002-001. It was also supported in part with resources and use of facilities through the Department of Veterans Affairs. We also acknowledge the support from the following CTSAs funded by NCATS: CWRU: UL1TR000439, OSU: UL1RR025755, U Penn: UL1RR024134 & UL1TR000003, Boston: UL1RR025771, Stanford: UL1TR000093, Tufts: UL1RR025752, UL1TR000073 & UL1TR001064, University of Illinois: UL1TR000050, University of Pittsburgh: UL1TR000005, UT Southwestern: 9U54TR000017-06, University of Utah: UL1TR000105-05, Vanderbilt University: UL1TR000445, George Washington University: UL1TR000075, University of CA, Davis: UL1TR000002, University of Florida: UL1TR000064, University of Michigan: UL1TR000433, Tulane University: P30GM103337 COBRE Award NIGMS, Wake Forest University: UL1TR001420. The PWV ancillary study was supported by NHLBI (Mark Supiano: R01HL107241). Kristen Nowak is supported by NIDDK (K01DK103678). Anna Jovanovich is supported by Veterans Administration CDA 5IK2CX001030-03. DEW has participated in advisory boards for Janssen and Akebia and has represented Dialysis Clinic Inc. in advisory boards for Keryx and Relypsa. AJ receives study drug from Shire. Supplemental material.


Intraoperative blood pressure is a relevant variable for postoperative outcome in infants undergoing surgical procedures. It is therefore important to know whether the type of anesthesia has an impact on intraoperative blood pressure management in very low birth weight infants. Here, we retrospectively analyzed intraoperative blood pressure in very low birthweight infants receiving either awake caudal anesthesia without sedation, or caudal block in combination with general anesthesia, both for open inguinal hernia repair.Ethical approval was provided by the University of Tuebingen Ethical Committee on 05/29/2018 with the project number 403/2018BO2. Patient records of infants admitted by the neonatologist  which were scheduled for inguinal hernia repair were retrospectively evaluated for the course of mean arterial blood pressure and perioperative interventions to stabilize blood pressure. A total of 42 patients were included, 16 patients  received awake caudal anesthesia, 26 patients  a combination of general anesthesia and caudal block.p < 0.001). Patients in the latter group showed a significantly larger drop of mean arterial blood pressure below 35 mmHg  and a significantly longer time of mean arterial blood pressure below 35 mmHg , although they received more volume and vasopressor boluses for stabilization .Approximately 3% of the measured mean arterial blood pressure values in the caudal anesthesia group were below a critical margin of 35 mmHg, in contrast to 47% in the combined anesthesia group (The study indicates that the use of caudal block as stand alone procedure for inguinal hernia repair in very low birthweight infants might be advantageous in preventing critical blood pressure drops compared to a combination of caudal block with general anesthesia. The outcome relevance of adequate blood pressure in pediatric surgery has been lately emphasized by several authors , 2. For Thus, to determine whether the use of caudal block as a stand alone method may be advantageous in preventing critical blood pressure drops in the care of very low birthweight infants, we performed a retrospective analysis comparing patients with either awake caudal anesthesia without sedation (CA), or with a caudal block in combination with general anesthesia (GA + CA).Ethical approval for this study was provided by the University of Tuebingen Ethical Committee on 05/29/2018 with the project number 403/2018BO2 (Chairperson Prof D. Luft). Anesthesia in both groups was performed by two senior anesthetists with more than 5 years of experience in the care of very low birthweight infants. Both anesthesiologists provided anesthetics of both types. The decision regarding the technique used was made up to their clinical preference.n = 52). We included only children who underwent an isolated inguinal hernia repair and who had no concomitant diseases (n = 42). Patients with congenital organ disorders like cardiovascular disease that could affect mean arterial pressure were not included into the study.Patient records of infants admitted by the neonatologist which were scheduled for inguinal hernia repair between 01/01/2012 and 05/22/2014 were retrospectively evaluated. All children with hernia repair during that period have been evaluated  and brain oxygenation in 180 children younger than 6 months. The authors stated that the mean arterial pressure is a good proxy of cerebral perfusion as they found that the CBF decreased proportionally with cerebral perfusion pressure. They regarded a mean arterial pressure beyond 35 mmHg during anesthesia to be safe and sufficient [Vital parameters were automatically recorded by use of a patient data management system ; Version H.02.01.001, Philips®). Evaluation of the data was carried out manually. Statistical analysis was performed by GraphPadPrism® 5.02. The Shapiro-Wilk’s test for normality was used to check for normal distribution. Normal distributed groups were compared with the 2-sample 2-sided t-test. Otherwise the Mann-Whitney-U Test was used.In this study a retrospective analysis was performed in very low birthweight neonates (birthweight 1000 – 1500 g) receiving inguinal hernia repair. Two groups were compared: neonates with awake caudal anesthesia without sedation (CA) and neonates with a caudal block in combination with general anesthesia (GA + CA). At our institution we left treating preterm neonates for inguinal hernia repair without caudal block over a decade, since we rated the well-known advantages of regional anesthesia as so convincing , 10. TheCaudal anesthesia was performed in patients in a lateral decubitus position with left side down. The puncture site was preoperatively anesthetized with EMLA®. After implementation of an intravenous infusion and monitoring of vital parameters the patient was placed in a lateral decubitus position with left side down. An Epican® Paed25G was guided by a SonoSite® M-Turbo with linear probe 5–13 MHz) in long axis in-plane-technique and the needle tip advanced under direct visualization. After negative aspiration, local anesthetic  was applied and its spread assessed by ultra sound . In order to facilitate intubation of the trachea the muscle relaxant vecuronium (0.1 mg/kg) was applied. General anesthesia was maintained with sevoflurane (0.5–2.9 Vol% corresponding to 0.3–1 MAC), 13 patients received additionally remifentanil (0.1–0.3 μg/kg/min)  recommendations for blood pressure measurement in children, cuff bladder width was at least 40% of the arm circumference halfway between the olecranon and acromion. The cuff covered at least 80% of the arm circumference.In Fig. In the following step we quantified these episodes with a critical mean arterial blood pressure. As depicted in Fig. Intraoperative interventions to stabilize blood pressure are summarized in Table In this retrospective study we evaluated the course of intraoperative blood pressure in very low birthweight infants who received either caudal anesthesia, as a stand alone method, or a combination of general anesthesia, and caudal anesthesia, both for inguinal hernia repair. Anesthesia in both groups was performed by senior anesthetists with more than 5 years experience in the care of very low birthweight infants. As reported in the results section we did not investigate the effects of general anesthesia as a stand alone method, although general anesthesia may still be used in many institutions for this type of surgery. In our opinion, the two study arms are justifiable since the aim of our study was to find out potential advantages of caudal anesthesia as a stand-alone method in preterm neonates. Furthermore, we know from literature that arterial blood pressure is not altered by caudal anesthesia in children receiving general anesthesia , a finding that was supported by a prospective study in neonates by Deng et al. in 2008 , 7.The most striking result is that the mean blood pressure was significantly lower in the GA + CA group although there were more pharmacological interventions like application of vasopressors or volume boluses. It is of even more importance that approximately 47% of the measured mean arterial blood pressure values in that group were below a critical margin of 35 mmHg, in contrast to only 3% in the CA group and that the cumulative time below 35 mmHg per patient was significantly longer. A safe lower limit of blood pressure in infants is still a matter of debate. The incidence of hypotension in preterm neonates seems to be inversely related to gestational age and birth weight . GeneralIn very low birthweight infants we use caudal anesthesia rather than spinal anesthesia since the success rates are significantly higher , 17, 18.The retrospective analysis suffers from some limitations like the limited number of patients being anesthetized by only two anesthetists or that an association of intraoperative hypotension to general anesthetics like remifentanil or sevoflurane cannot be derived. Likewise no sequelae could be recorded in this retrospective study. However, the anesthetists each had at least 5 years of experience in pediatric anesthesia and were aware of keeping the mean arterial pressure above 35 mmHg which was difficult in the group of combined general- and caudal anesthesia in spite of the use of volume boluses and vasopressors and resulted in significantly more episodes of critically low mean arterial blood pressure. In summary this preliminary study provides support for the use of caudal block as a stand alone method for the care of very low birthweight infants as it shows advantages in preventing critical blood pressure drops compared to a combination of caudal block with general anesthesia.


Although hyperuricemia has been shown to be associated with the progression of cardiovascular disorder and chronic kidney disease (CKD), there is conflicting evidence as to whether xanthine oxidase (XO) inhibitors confer organ protection besides lowering serum urate levels. In this study, we addressed the cardio-renal effects of XO inhibition in rodent CKD model with hyperuricemia. Sprague-Dawley rats underwent 5/6 nephrectomy and received a uricase inhibitor oxonic acid for 8 weeks (RK + HUA rats). In some rats, a XO inhibitor febuxostat was administered orally. Compared with control group, RK + HUA group showed a significant increase in albuminuria and renal injury. Febuxostat reduced serum uric acid as well as urinary albumin levels. Histological and immunohistochemical analysis of the kidney revealed that febuxostat alleviated glomerular, tubulointerstitial, and arteriolar injury in RK + HUA rats. Moreover, in the heart, RK + HUA showed individual myofiber hypertrophy and cardiac fibrosis, which was significantly attenuated by febuxostat. We found that renal injury and the indices of cardiac changes were well correlated, confirming the cardio-renal interaction in this model. Finally, NF-E2-related factor 2 (Nrf2) and the downstream target heme oxygenase-1 (HO-1) protein levels were increased both in the heart and in the kidney in RK + HUA rats, and these changes were alleviated by febuxostat, suggesting that tissue oxidative stress burden was attenuated by the treatment. These data demonstrate that febuxostat protects against cardiac and renal injury in RK + HUA rats, and underscore the pathological importance of XO in the cardio-renal interaction. Although the frequent association of CVD with CKD suggests the pathogenic link between these conditions, the underlying mechanisms remain unclear. Besides several common risk factors of CKD and CVD such as hypertension, ischemia, and impaired glucose tolerance, several lines of evidence indicate that the disturbed uric acid (UA) metabolism may mediate cardio-renal syndrome3. In CKD, the reduced excretion of UA from the kidney results in the elevation of serum UA levels, and we have previously demonstrated that hyperuricemia, in turn, contributes to the progression of kidney injury5. Importantly, hyperuricemia has also been reported to be associated with increased risk for incident coronary heart disease and heart failure7, supporting that UA is one of the key factors of the cardio-renal interaction.Chronic kidney disease (CKD) has increasingly been recognized as an important contributor not only of end-stage kidney disease but also of cardiovascular disease (CVD). Decreased glomerular filtration rate (GFR) and albuminuria increase the risk of CVD independently of other atherosclerosis risk factors10; however, clinical data to date are still controversial. A recent cohort study comparing gout patients on XO inhibitors (XOIs) with non-treated subjects who have hyperuricemia showed that XOIs had no effect on cardiovascular risk11. In another study, the administration of a XOI, febuxostat, did not show significant renoprotective effect in hyperuricemic stage 3 CKD patients12. In contrast, in a very recent report, febuxostat was shown to reduce the primary composite endpoint of cerebral, cardiovascular, and renal events and all deaths as compared with non-febuxostat group in patients with 65 years or older with hyperuricemia13. In the Cardiovascular Safety for Febuxostat and Allopurinol in Patients with Gout and Cardiovascular Morbidities (CARES) trial, febuxostat was noninferior with respect to adverse cardiovascular events14. However, cardiovascular mortality was higher with febuxostat than with allopurinol in patients with gout and cardiovascular disease. These inconsistent results may be due to the differences in study design, baseline characteristics, and the rate of GFR decline15. Currently, it is still inconclusive whether XOIs can confer organ protection besides reducing circulating UA levels.Given the possible role of hyperuricemia in the progression of CKD and CVD, a potential benefit for the xanthine oxidase (XO) inhibition has been studied5. However, it was unclear whether the use of XOIs was able to confer cardio-renal protection. In this study, we tested whether XO inhibition ameliorates cardiovascular and renal dysfunction in a model of CKD with hyperuricemia.Previously, we demonstrated that the disturbed UA metabolism is associated with albuminuria and glomerular podocyte injury in experimental hyperuricemic rats16. In brief, rats received the surgical resection of the upper and lower one-thirds of the left kidney. The resected portion of the left kidney was weighed to validate the procedure. One week later, the rats received right uninephrectomy. Rats were divided into three subgroups: 1) Control group (n = 6), 2) RK with oxonic acid group , 3) RK with oxonic acid and Febuxostat group . Control rats received standard diet  and tap water. RK rats received oxonic acid , a uricase inhibitor 17. Febuxostat was dissolved in drinking at a concentration of 0.03 mg/L. At this concentration, the dose of febuxostat was calculated as ~3 mg/kg/day18. Systolic BP was measured by the tail-cuff method . Urine was collected for 24 hours using individual metabolic cages. At 8 weeks, animals were euthanized under anesthesia using inhaled isoflurane for sample collection. Blood samples were obtained by Inferior vena cava. Kidney and heart were removed and were snap-frozen until use.Animal procedures were approved by the Teikyo University Ethics Committee for Animal Experiments  and were conducted in accordance with the guidelines of the Institute Animal Care and Use Committee of the Teikyo University. Male Sprague Dawley rats at 6 weeks of age were obtained from Sankyo Labo Service . After baseline blood pressure (BP) measurement, rats were randomly assigned to the remnant kidney (RK) group or the sham-operated control group. RK model was created as described previouslySerum UA concentrations were determined using high-performance liquid chromatograph equipped with a UV spectrophotometric detector . UA standard  was dissolved in 2 mmol/L ammonium hydroxide solution. Serum samples were centrifuged and filtered through a Millipore filter . Samples were injected onto a Wakopak Wakosil GP-N6 column  with mobile phase of 98% (v/v) 0.2 mol/L sodium phosphate buffer, pH6.0, and 2% (v/v) acetonitrile at a flow rate of 0.5 mL/min. Under these conditions typical retention time for uric acid (detected at 284 nm) was 3.68 min. Urinary albumin, urinary creatinine, and serum creatinine were measured by ELISA .19.Methyl Carnoy’s solution-fixed, paraffin-embedded sections (1 μm) were stained with the periodic acid-Schiff (PAS) reagent for light microscopy. On coronal sections of the kidney, at least 20 glomeruli were examined to evaluate glomerular hypertrophy as described previously19. Primary antibody included antibodies against desmin , type III collagen , and α-SMA . To assess the desmin-positive area, the digital images at ×400 magnification were analyzed using Aperio ImageScope. The percent positive area was determined as the diaminobenzidine-positive pixel per total pixel in the glomerulus. Likewise, positive area for type III collagen in interstitium was determined as percent positive area with 15 fields (each field/0.4 mm2). Quantitative analysis of afferent arterioles was performed as described previously20. For afferent arterioles, vessels with internal elastic lamina adjacent to glomeruli were selected. Areas positive for α-SMA in the cross section of these vessels were quantitated using Aperio ImageScope . Kidney sections were observed by two investigators in a blinded manner.Immunohistochemistry was performed as described previously21. We quantified cross-sectional area of 25 cells per field at 4 fields. Additionally, heart sections were stained with sirius-red stain to distinguish areas of connective tissue as previously described22. Positive areas were quantified using Aperio ImageScope (eight fields were randomly selected on each section). The value was expressed as the ratio of sirius red-stained fibrosis area to total area.For the histological evaluation of the heart, short-axis slices of the heart at the level of papillary muscle were washed with saline, immersed in 10% Mildform, fixed for one day, and embedded in paraffin. Hematoxylin and eosin (HE)-stained heart sections were used to quantify myocardial thickness by measuring the distance from the inner to the outer myocardial edges at the mid-papillary level. Mean left ventricular wall thickness was calculated from seven measurements of wall thickness taken at 0, 30, 60, 90, 120, 150, and 180 degrees along the hemicircle of the short axis of the left ventricular wall, and the average was used to calculate mean ventricular thickness. Myofibril cross-sectional areas were evaluated using wheat germ agglutinin (WGA)-stained sections19. Briefly, samples were subjected to SDS-PAGE and transferred onto a nitrocellulose membrane. After overnight incubation with primary antibody at 4 °C, membrane was incubated with secondary antibody linked with horseradish peroxidase for 1 h at RT. Signal was detected by Immun Star HRP . The density of each band was determined using Multi Gauge software  and expressed as a value relative to the density of the corresponding band of the GAPDH. As primary antibodies, Nrf2 antibody  and heme oxygenase-1 (HO-1) antibody  were used. Full-length blots are shown in Supplemental Fig. Kidney cortex and heart were homogenized in cell lysis buffer  and Western blotting was performed as described previouslyAll values are expressed as mean ± SD. Comparison of continuous variables among three groups was performed by ANOVA, followed by Tukey’s HSD post hoc test. Linear regression analysis was performed by Pearson correlation. All statistical analyses were conducted using Graph Pad Prism 7 . A value of P < 0.05 was considered statistically significant.Male Sprague Dawley rats were randomly assigned to one of three subgroups: 1) control group (n = 6), 2) remnant kidney (RK) with oxonic acid group , 3) RK with oxonic acid and febuxostat group  (see Methods). Biological data in each group at 8 weeks are shown in Table 23  and with myofibril hypertrophy    Fig. . In addi02) Fig. . These d25. Several lines of evidence also indicated that increased UA levels can also result in intracellular oxidative stress27. In addition, XOIs not only reduce UA production during purine metabolism, they also decrease oxidant stress formation such as H2O2 and O2−. The Kelch-like ECH-associated protein 1 (Keap1)-NF-E2-related factor 2 (Nrf2) system serves as the physiological sensor of cellular oxidative stress29. In response to increased reactive oxygen species, covalent modification of several key cysteine residues in the ubiquitin ligase component Keap1 impairs the binding to the substrate Nrf2, resulting in its accumulation. Increased Nrf2, in turn, induces antioxidant proteins such as heme oxygenase 1 (HO-1)29. To determine oxidative stress burden in our model, we evaluated Nrf2 levels in the kidney and in the heart by Western blotting. We found that Nrf2 levels were significantly increased in the kidney as well as in the heart in RK + HUA group 34. Given these results, it may be that the anti-oxidant mechanism is upregulated in response to oxidative stress at an early stage of CKD, however the response to oxidant stress is compromised at an advanced stage possibly due to the accumulation of uremic toxins, facilitating oxidative stress accumulation and tissue damage. Currently, several clinical trials that evaluate the protective effects of Nrf2 activators are ongoing35. These studies will clarify the role of the Keap1/Nrf2 system in CKD progression.Another interesting observation is an altered activity of Keap1-Nrf2 system in our model. In a basal condition, the abundance of the transcription factor Nrf2 is suppressed through the proteasomal degradation that is controlled by the oxidative stress sensor Keap136. It has also been shown that plasma XO activity is increased in hypertensive subjects, which is associated with cardiac hypertrophy37. Consistently, XOIs have been shown to reduce BP in hypertensive animal models38. In addition, the BP-lowering effects of XOI have also been reported in humans39. Our data are in line with these data, and the protective effects of febuxostat observed in our study may in part be explained by the reduction in BP. However, the fact that the BP difference between RK + HUA and RK + HUA + Feb rats did not reach statistical significance also points to the additional contribution of BP-independent factors.In this study, febuxostat induced a non-significant decrease in BP in hyperuricemic CKD rats. XO has been shown to be widely distributed across the body, including liver, kidney, heart, and capillary endothelial cells40. The increase in extracellular UA levels above the solubility facilitates the formation of monosodium urate crystals, which triggers tissue inflammation through NALP3 inflammasome and other pathways41. Besides these mechanisms, several lines of evidence indicate that intracellular urate triggers a number of pathological mechanisms such as the activation of renin-angiotensin system, NADPH oxidase, and endothelin-141. In addition, XO generates H2O2 and O2− in the process of purine metabolism, which is also implicated in tissue damage42. In accordance with previous observations17, we did not observe any crystal formation in the kidney (data not shown). This is explained by the fact that serum UA levels in the hyperuricemic rats were well below the maximal solubility in the extracellular milieu, although the levels were increased by approximately two fold compared with control group. In our study, contribution of oxidative stress is indicated by the activation of Nrf2 both in the kidney and in the heart; however, future studies are required to determine to what extent the intracellular UA contributed to the increased oxidative stress burden in our model.Accumulating data indicate that tissue damage associated with the disturbed UA metabolism is mediated by both urate crystal-dependent and -independent mechanisms43. Interestingly, the authors reported that XO knock-in mice showed significant increase in tumor growth compared with wild-type or XDH knock-in mice and that these effects were mediated by ROS production by XO knock-in macrophages. These data clearly indicate the physiological importance of XO/XDH balance in the immune system. Although we did not address XO or XDH activity in our study, previous evidence demonstrated that XO activity is elevated in the rat remnant kidney model44. The involvement of XO is also reported in other hypertensive kidney disease models38. Given these data, it is likely that the dysregulated XO activity and/or XO/XDH imbalance is involved in our model, which can be implicated in the cardio-renal protective effects of febuxostat observed in the study.A recent study reported the phenotype of xanthine dehydrogenase (XDH)-stable and XO-locked knock-in mice46. In a recent study by Fujii et al.45, febuxostat promoted ATP recovery in the ischemia/reperfusion injury model, which was associated with the attenuation of kidney dysfunction. In another study, febuxostat increased intracellular ATP levels in bone marrow-derived macrophages, improving cellular bioenergetics46. Similar to the ischemia/reperfusion injury model, tissue ATP levels in the kidney is shown to be reduced in the remnant kidney rat47. Although we did not evaluate tissue ATP content in our study, the contribution of cellular bioenergetics in the protective effects in our model warrants further investigation.Another possibility that can potentially explain the protective effects of febuxostat is its effect on cellular ATP production. Indeed, several studies demonstrated that febuxostat alters ATP levels by activating purine salvage pathwayIn summary, our study demonstrated that the cardiac and renal injury in hyperuricemic CKD rats is attenuated by febuxostat. These data indicate the therapeutic potential of XOIs in cardiovascular and kidney dysfunction in hyperuricemic CKD, and also implicate XO in cardio-renal syndrome.Febuxostat was provided by Teijin Pharma. S.S. received research funding from Teijin Pharma. The company had no role in study design, execution of experiments, decision to publish, or preparation of the manuscript.Supplementary information.


Measurements of plantar loading reveal foot-to-floor interaction during activity, but information on bone architecture cannot be derived. Recently, cone-beam computer tomography (CBCT) has given visual access to skeletal structures in weight-bearing. The combination of the two measures has the potential to improve clinical understanding and prevention of diabetic foot ulcers. This study explores the correlations between static 3D bone alignment and dynamic plantar loading.Sixteen patients with diabetes were enrolled (group ALL): 15 type 1 with  and without  diabetic neuropathy, and 1 with latent autoimmune diabetes. CBCT foot scans were taken in single-leg upright posture. 3D bone models were obtained by image segmentation and aligned in a foot anatomical reference frame. Absolute inclination and relative orientation angles and heights of the bones were calculated. Pressure patterns were also acquired during barefoot level walking at self-selected speed, from which regional peak pressure and absolute and normalised pressure-time integral were worked out at hallux and at first, central and fifth metatarsals (LOAD variables) as averaged over five trials. Correlations with 3D alignments were searched also with arch index, contact time, age, BMI, years of disease and a neuropathy-related variable.p < 0.05) correlations with LOAD. These were weak-to-moderate in the ALL group, moderate-to-strong in N and D. LOAD under the central metatarsals showed moderate-to-strong correlation with plantarflexion of the 2nd and 3rd phalanxes in ALL and N. LOAD at the hallux increased with plantarflexion at the 3rd phalanx in ALL, at 1st phalanx in N and at 5th phalanx in D. Arch index correlated with 1st phalanx plantarflexion in ALL and D; contact time showed strong correlation with 2nd and 3rd metatarsals and with 4th phalanx dorsiflexion in D.Lateral and 3D angles showed the highest percentage of significant (These preliminary original measures reveal that alteration of plantar dynamic loading patterns can be accounted for peculiar structural changes of foot bones. Load under the central metatarsal heads were correlated more with inclination of the corresponding phalanxes than metatarsals. Further analyses shall detect to which extent variables play a role in the many group-specific correlations. Diabetes is a pandemic, with a forecast of up to 600 million patients all over the world by 2045 . ParticuKnowledge and prevention of diabetic foot disorders are thus important and may be improved by biomechanical measurements in real patients. The literature has long reported static and dynamic plantar loading assessments alone, but more recent studies have proposed integration with kinematics measurements , especiaOnly one recent study has reported data on the possible relationships between 3D bone orientation and plantar loading . HoweverThe present study is primarily aimed at exploring possible correlations between foot bone position and orientation 3D measurements from CBCT scans, i.e., in static conditions, and regional plantar loading from plantar pressure measurements during barefoot level walking, i.e., in dynamic conditions. The main hypothesis is that changes in 3D forefoot architecture correlate with foot dynamic loading alterations. This is meant to contribute to the prevention of the risk of foot ulceration in patients with diabetes, finally understanding which foot bone abnormalities may have an impact on plantar pressure. The study is secondarily aimed at exploring possible correlations between the bone 3D measurements and the major functional, biological and clinical parameters, namely arch index and contact time, age, and neuropathy-related measures.Sixteen patients with diabetes performed two data acquisition sessions, the CBCT static scan and the plantar pressure analysis during gait. These patients were grouped as follows: 8 type 1 diabetes without (D) and 7 with (N) neuropathy, and 1 with latent autoimmune diabetes of the adults (LADA), all together in the ALL group. Those patients with two out of the following three conditions  were assBoth feet were scanned  in single-leg upright posture Fig. a, with tFor each of these bone models, an anatomical reference frame was defined using the Principal Component Analysis (PCA) Fig. e, f 22]22]. This2; range 0–1270 kPa; 100 Hz) , BIOLogical [BMI], and CLINical  variables:CTContact timeAIArch indexBMIBody mass indexYODYears of diseaseNS-VPTNeuropathy Score and Vibration Perception Threshold


IntroductionThere is increasing recognition of dry eye disease (DED) as a significant factor influencing quality of life in seemingly normal individuals. Our goal was to determine the distribution of Ocular Surface Disease Index (OSDI) scores in non-clinical individuals in Karachi, Pakistan.MethodsWe distributed OSDI questionnaires to subjects aged > 18 years with no active ocular complaint. Examiners were selected from various areas of the city to administer questionnaires to students and the general population. The OSDI score was grouped as per the following: normal (0-12 points), mild (13-22 points), moderate (23-32 points), and severe (33-100 points).ResultsWe surveyed 2433 individuals with a mean age of 30.7±15.6 years. Additionally, the mean OSDI score was 22.4±18.7. To estimate prevalence, we used two OSDI score cutoffs: >13 (64.4%) and >22 points (43.6%). Statistical significance was found using multivariate regression in the following variables: age (p<0.001), contact lens wear (p<0.001), ocular allergies (p<0.001), hypertension (p<0.001), diabetes (p=0.003), and smoking (p=0.047). When graphing mean age against OSDI score, there was a large jump between the third and fourth decades; thereafter, there was a steady increase. Similarly, when plotting smoking, the score was steady until five years and then there was a sharp incline.ConclusionThere was a high prevalence of DED in the studied population. Additionally, many systemic and ocular factors were associated with this disease. The International Dry Eye Workshop (DEWS) II has defined dry eye disease (DED) as a multifactorial disease affecting both the ocular surface and the tear film in which increased tear film hyperosmolarity, ocular surface inflammation, and neurosensory problems can play a causative role . The preSeveral tools have been created to screen for this disease effectively and efficiently. These include the Ocular Surface Disease Index (OSDI), Impact of Dry Eye on Everyday life (IDEEL) , and theTo our knowledge, no study has observed the prevalence of DED and observed its trends in a large population in Pakistan. This is precisely the primary goal of this study. The secondary goals are to observe the association of the OSDI score with a variety of demographic factors.This was a cross-sectional study conducted in the city of Karachi, Pakistan, to assess the symptoms of dry eyes using the OSDI . Additionally, we also assessed risk factors like contact lens use, smoking, surgery, and alcohol use. The Ethics Committee of Hashmanis Hospital approved this study according to the tenets of the Declaration of Helsinki. Informed consent was obtained from each participant.Samples and questionnaireExaminers were selected from various areas of the city to administer questionnaires to other students and the general population using convenience sampling. Subjects over the age of 18 years were included in the study. This study was conducted in residents with no active ocular problems. We excluded patients with evidence of ocular surface disease and known autoimmune conditions.The questionnaire was divided into two parts. The first part asked about history including smoking history or contact lens use. Additionally, it inquired about their comorbidities like hypertension and diabetes. The second part was the OSDI questionnaire where subjects were asked to describe their symptoms over the previous week. The questionnaire was administered as a guided interview in two languages, English and Urdu.The OSDI questionnaire assesses 12 items that evaluate both the symptoms of dry eye and its effect on the vision. There are three sections that evaluate visual complaints, symptoms, and any environmental triggers. The respondent is asked to list his complaints ranging from 0-4; 0 being “none of the time” and 4 equating to “all of the time.” The total score was calculated via the following formula: OSDI = ] .The OSDI score was grouped as per the following: normal (0-12 points), mild (13-22 points), moderate (23-32 points), and severe (33-100 points) . GroupinSample sizeopenepi.com) to determine the sample size. We used an estimated frequency of 33% [We used the openepi calculator . Descriptive statistics were used for calculating mean and standard deviations. Prevalence was determined with four different methods: an OSDI of >13 and >22 and those with and without ocular factors. A Pearson correlation test, independent t-test, and multivariate regression were used for the various variables. Graphs were created using Microsoft Excel . A p-value of < 0.05 was considered significant.General characteristicsWe surveyed 2433 individuals with a mean age of 30.7±15.6 years. Additionally, the mean OSDI score was 22.4±18.7. The rest of the data can be seen in Table We then repeated this analysis with the exclusion of patients with the following: a history of ocular surgery n=139), contact lens use (n=601), and ocular allergies (n=391). The prevalence using this data came out to be 55.3% (> 13), and 33.9% (> 22). The distribution of the OSDI score can be seen in Figure 39, contaVariablesStatistical significance was found in the following variables: age (p<0.001), contact lens wear (p<0.001), ocular allergies (p<0.001), hypertension (p<0.001), diabetes (p=0.003), and smoking (p=0.047). The rest of the data can be seen in Table The effect of age on the mean OSDI score has been plotted in Figure We performed a cross-sectional analysis using the OSDI questionnaire to understand the distribution of dry eye symptoms across a non-clinical population. Additionally, we observed the associations and trends of several factors that could possibly influence this disease.There is a large variation in the prevalence of DED across the world. Studies in India , Jordan Therefore, we have reported values with a minimum value of 13 (mild) and 22 (moderate), as the true prevalence likely lies between these estimates. Furthermore, we subdivided our population further into those without ophthalmic factors affecting the ocular surface and those with. Therefore, we have reported a total of four prevalence values. The true prevalence lies between 33.9%-64.4%, depending on the criteria employed.Many studies have linked the female gender as a risk factor for DED -12. One Age has also been shown to be a risk factor; our study agrees with this finding. There are a range of etiologic factors that have been postulated; for example, a higher incidence of comorbidities like diabetes, lowered corneal sensitivity , dysfuncSmoking has been a controversial risk factor for the development of DED. A few studies show an effect of smoking on the OSDI -21 whileWe found a significant difference in those suffering from diabetes and hypertension. Previous studies agree with this result -23. It iThere are several limitations to this study. Firstly, we did not correlate symptoms with objective signs on clinical tests. However, there are reports showing a weak association between the two; this is an area requiring further study . SecondlThere is a high prevalence of DED in the population residing in Karachi, Pakistan. The exact number is hard to estimate due to various parameters that can be used. When attempting to maximize sensitivity, like other studies, we demonstrate a larger prevalence in this population when compared to others. Additionally, we demonstrate a range of factors like age, contact lens wear, ocular allergies, hypertension, and diabetes that can influence DED.


The ultrasound based non-invasive ICP measurement method has been recently validated. Correlation of symptoms and signs of intracranial hypertension with actual ICP measurements in patients with large intracranial tumors is controversial. The purpose of this study was to assess ICP in patients with brain tumors, presenting with neurological signs and symptoms of elevated ICP and to further evaluate the value and utility of non-invasive ICP monitoring.Twenty patients underwent non-invasive ICP measurement using a two-depth transcranial Doppler ultrasound designed to simultaneously compare pulse dynamics in the proximal , and the distal  intraorbital segments of the ophthalmic artery through the closed eyelid.3, mean = 48.81 cm3), perilesional edema , and midline shift (mean = 3.99 mm). All ICP measurements were in the normal range of 7–16 mmHg (ICPmean: 9.19 mmHg). The correlation of demographics, clinical and radiological variables in a bivariate association, showed a statistically significant correlation with neurological deficits and ICPmax (p = 0.02) as well as ICPmean (p = 0.01). The correlation between ICP and neurological deficits, showed a negative value of the estimate. The ICP was not increased in all cases, whether ipsilateral nor contralateral to the tumor. The multivariate model analysis demonstrated that neurological deficits were associated with lower ICPmax values, whereas maximum tumor diameter was associated with larger ICPmax values.Forty-eight measurements were analyzed. Radiological characteristics included tumor volume (range = 5.45–220.27cmThis study demonstrated that ICP in patients with intracranial tumors and mass effect is not necessarily increased. Therefore, clinical signs of intracranial hypertension do not necessarily reflect increased ICP. For decades, neurosurgeons and neuro-oncologists assumed that the mass effect of brain tumors with peritumoral edema or intratumoral hemorrhage leads to increased intracranial pressure (ICP) . This asQuite surprisingly, there is remarkably little evidence supporting the assumption that intracranial lesions with mass effect categorically result in raised ICP. On one hand, raised ICP is certainly associated with a number of historically pathognomic signs and symptoms including headache, nausea, vomiting, papilledema and neurological deficits –5. On thA medical device allowing non-invasive ICP measurement without a relevant risk of side effects could substantially add to our knowledge of ICP dynamics in patients in whom invasive measurement is not otherwise clinically warranted. This group includes many patients with newly diagnosed brain tumors presenting with clinical and radiological signs of intracranial hypertension. Having this in mind, our group recently published the results of a validation pilot study on non-invasive ICP measurement method including 78 simultaneous paired invasive and non-invasive ICP values . In thisThe overall aim of the current study was to a) explore the relationship between intracranial tumor volume and ICP as well as b) identify the clinical factors associated with increased ICP.All patients with intracranial tumors, and signs of mass effective brain tumors were screened for study inclusion between December 2014 and January 2016. Mass effect was defined in terms of clinical  and/or radiological  signs of intracranial hypertension.The study was approved by the local ethics commission (EKNZ Nr.2016–00507). Patients were either referred to our emergency department or admitted for elective surgery. All patients or their family provided written voluntary consent prior to the study enrollment.The ICP measurement instrument used in this trial  was developed at the Health Telematics Science Institute at the Kaunas University of Technology, Lithuania . A pilotThe measurement technique is based on the use of transorbital Doppler ultrasound of the ophthalmic artery (OA), as a natural ICP sensor. The OA has two major segments. The first, proximal or intracranial segment originates at the carotid artery and extends to the optic canal (OC), at which point it perforates the dura. The second, distal or intraorbital segment originates distal to the OC and accompanies the optic nerve within the orbit to the retina.Although the proximal and distal OA are adjacent and continuous, they have different pulse dynamics. These differences, which can be demonstrated in waveform measurements obtained using transorbital Doppler ultrasound, reflect differences in transmural pressure. Inasmuch as there are no other pertinent physiological or anatomical factors distinguishing the proximal and distal segments of the OA or contributing to the differences in transmural pressure, the differences in pulse dynamics are attributed to the influence of ICP. Proximal to the canal, the OA is subject to ICP. Distal to the canal, in the orbit, it is not.These characteristics serve as the basis for non-invasive ICP monitoring. Insofar as the tissues of the orbit are non-compressible, pressure applied to the orbit is transferred to the distal OA. It is possible to balance the pulse dynamics of the proximal and distal OA through the application of gentle pressure to the orbit. When the pressure applied equals the ICP, the pulse dynamics and the waveforms equilibrate. The pressure required to reach the point of equilibration, the “balance point,” is equal to the ICP and can be read out from the ICP monitoring instrument.Inasmuch as neither individual patient calibration nor zero-level calibration is required, this method can be said to deliver a measurement of absolute, rather than relative intracranial pressure.In this study, pulse dynamics were assessed using a customized trans-orbital Doppler ultrasound device and a narrow tubular two-depth single beam transducer. The transducer is inserted into a fitting on a plastic frame strapped around the head Fig. . The fitMeasurements may be taken from either side. The side chosen most often reflects the preferences of the examiner unless previous orbital injury or other ocular history presents a contraindication to one side. Otherwise the second side is reserved for re-measurement and confirmation, or in the event of failure to complete the measurement.An air-inflatable doughnut shaped cushion is positioned between the frame and the orbit on the side chosen for measurement. The cushion is used to apply pressure to the orbit. The transducer passes through the opening in the cushion, positioned against the closed eyelid, aimed and then fixed in place. Pressure in the cushion is measured continuously in mmHg throughout the measurement procedure. The ICP measurement procedure is fully automated from the point at which the position of the ultrasonic transducer has been optimized and fixed.The actual measurement technique involves the following steps: pressure is applied to the tissues surrounding the eyeball, and increased automatically in steps of 2.0 or 4.0 mmHg. The maximal duration of each step is limited to 40 s. The software built into the ICP meter automatically detects the point of equilibrium at which the waveforms of the proximal and the distal segments of the OA are matched. The amount of pressure externally applied to the orbit at this point equals the ICP.We attempted to perform non-invasive ICP measurements in all patients on both eyes and if patient compliance allowed, multiple measurements were done. All measurements were obtained in supine position by experienced neurovascular doppler ultrasound technicians with specific training for the non-invasive ICP device.Out of 53 measurement attempts, 48 measurements were reliable and repeatable and were therefore included in this analysis (Supplementary Table 3) were performed using Elements software . The investigators performing the imaging analysis were blinded to the clinical findings and non-invasive ICP values.All patients underwent detailed case-history and neurological examination prior to the measurement with special attention to the classic signs of raised intracranial pressure including headache, vomiting or impaired consciousness. All patients underwent magnetic resonance imaging (MRI) for preoperative morphologic evaluation and intraoperative navigation purposes. Evaluation of the MRI included signs of intracranial hypertension: Tumor size and volume, peritumoral brain edema volume, and midline shift (MLS). Midline shift was measured at the level of the foramen of Monro. Volumetric measurements of the tumor mass and perifocal edema (cmmax) for each patient. Secondary endpoints included ICP on the affected side of the brain (ICPaff): Mean ICP in left hemisphere for left-sided tumors and on the right for right sided tumors. At the same time arithmetic mean overall ICP value (ICPmean) for each patient as well as individual ICP values for each side of each patient were calculated.The primary endpoint was set as the maximum ICP value (ICPmax) and all other variables. Associations of ICPmax with categorical explanatory variables were investigated by Wilcoxon rank sum tests (Mann-Whitney test), estimating the difference between groups together with a 95% confidence interval. Associations of the ICPmax with continuous explanatory variables were investigated with linear regression, estimating the effect size together with a 95% confidence interval. In order to achieve an optimal multivariate model to explain the ICPmax, the ICPaff and the ICPmean, a model with a maximum of two explanatory variables was evaluated and a forward-selection approach was used based on the Akaike information criterion to find the most relevant explanatory variables.We used a bivariate association analysis to investigate associations between maximum ICP value  were included in the final analysis of this pilot study. The mean age at the time of surgery was 63.8 ± 13.2 years (range 41–83 years). The majority of tumors were located supratentorial and only three were infratentorial. Most common histological tumor diagnosis was meningioma followed by glioma, and metastases. Demographic and patients’ characteristics are shown in Table 2 male weAll patients were awake and cooperative during the non-invasive ICP measurements. Neurological assessment categorized all patients as GCS 14 or 15. Preoperative common symptoms included seizures, neurocognitive and sensorimotor deficits. Potential clinical signs of raised intracranial pressure such as headache were found in 6 patients (30%). In our series, 11 patients (55%) had been placed on steroids a few days prior to non-invasive ICP measurement as a treatment of symptoms as well as preparation for surgery due to pertinent edema in the MRI findings.3 (range 5.45–220.27cm3) and mean edema volume was 74.40cm3 (range 0 to 238.27cm3). A large edema volume of >100cm3 was present in 6 (30%) cases. Histologically this subgroup included 3 meningiomas, 2 lymphomas, and one metastasis.Mean tumor volume was 48.81cmOverall mean midline shift (MLS) was 4 mm. The MLS ranged from an absent MLS to a maximum of 16 mm, which was present in 9 patients (45%). Tumor and edema volumes are shown in Table mean was 9.19 mmHg, the mean ICPmax was 10.65 mmHg, and the mean ICP on the affected hemisphere side (ICPaff) was 8.81 mmHg  and ICPmean (p = 0.01), meaning that patients with neurological deficits had a − 5.81 mmHg lower ICPmax than patients without neurological deficits  a negative correlation with ICP and neurological deficits, and 2) a positive correlation between ICP and maximum tumor diameter. It was particularly interesting to note the negative correlation between ICP and neurological deficits. However, these results have to be interpreted carefully, because only 2 out of 20 patients had no neurological deficits. In a precise neurological examination almost all patients with mass effective brain tumor reveal some kind of neurological deficits. Therefore, this negative correlation might be influenced by observational factors such as sampling error. Additionally, it is also possible that patients with a neurological deficit self-selected and presented earlier, before increased intracranial pressure occurred.So far, only a few case reports and series of brain tumor associated increased intracranial pressure have been reported. Tumor entities were metastasis , meningiHung et al.  measuredmax of 10.65 mmHg might qualify as increased, relatively speaking.Currently, we assume normal ICP value to be in a range between 7 and 15 mmHg, with the patient in 0° supine position . In oppoThe Monro-Kellie doctrine describes certain aspects of pressure-volume-relationship: The volume-sum of brain, CSF and intracranial blood remains constant . The latThe significance of our findings is that space-occupying lesions, surrounded by perifocal edema, do not necessarily result in increased intracranial pressure. A higher ICP was anticipated for intra-axial fast growing lesion, but this could not be confirmed. Meningioma grade I are slow growing extraaxial lesions, therefore giving the intracranial space more time for compensation mechanism of volume increase. On the contrary, high-grade gliomas are intraparenchymatous lesions and grow rapidly with a median growth rate of 0.14 cc per day and therefore shorter period for adjustment of regulatory mechanism .Furthermore, ipsi- and contralateral hemispheric ICP values were compared, assuming that we would expect a higher ICP on the side of the lesion. Contradictory, no correlation between ICP values and tumor lateralization could be found. Finally, tumor growth seems to affect both hemispheres equally.The mass effect in brain tumor cases is often not only caused by the tumor mass itself but mainly by peritumoral brain edema. For more than 5 decades, steroids are used in neurosurgical patients to reduce peritumoral brain edema (PTBE), for symptom relief, to reduce mass effect and risk of brain swelling during surgery .For instance in meningiomas, approximately 60% of patients present with peritumoral edema . In the An earlier study investigated the ICP course after steroid treatment in patients with PTBE . A totalNarotam et al. indicated in their study, that contralateral ventricular dilation is an early indicator of intracranial hypertension . Indeed,The main limitation of this pilot study is the low number of patients and the heterogeneity of histological diagnosis. Another aspect is that our measurements were only done at a certain time point and as ICP can be fluctuating, an increase in ICP might not be displayed. Continuous monitoring would therefore be necessary, which is not available with the non-invasive ICP measurement technique at this time. Although one patient in this series deteriorated before ICP measurement, our patients could finally still not have reached the point of decompensation and ICP increase.Future studies are ongoing  to better characterize the dynamics of intracranial pressure in a larger series of patients presenting with brain tumor, and to assess applicability of non-invasive intracranial pressure monitoring.ICP in patients with intracranial tumors and mass effect is not proven to be increased. Clinical signs of intracranial hypertension do not necessarily reflect increased ICP, and therefore non-invasive ICP measurement might become an important tool in preoperative assessment of these patients in order to determine timing of surgery and the role of complementary medical interventions.Additional file 1. Supplementary table with all obtained non-invasive ICP measurements in our cohort.


Secondary hyperparathyroidism (SHPT) is a common complication in end-stage renal disease (ESRD) patients, and parathyroidectomy (PTX) is an effective treatment intervention of SHPT. However, the curative impact of PTX on left ventricular function still remains incompletely understood. To evaluate the impact of parathyroidectomy on left ventricular function in ESRD patients, we conducted this retrospective study.Between Oct 1, 2010 and Oct 1, 2016, ESRD patients presented with SHPT who underwent parathyroidectomy were enrolled. We retrospectively collected the ultrasonic cardiogram parameter pre- and 1-year post-PTX, and analyzed the influence factor for the overturn of left ventricular hypertrophy (LVH) and the improvement of ejection fraction% (EF%).p<0.001) and the left ventricular mass index (LVMI)  g/m2 vs. 123.54  g/m2, p<0.001) significantly declined after 1 year of the PTX. Further, 43.75% patients diagnosed with LVH before the PTX have recovered from LVH. In the subgroup analysis of 35 patients with EF% ≤ 60% pre-PTX, EF% and fractional shortening% (FS%) significantly improved after 1 year of the PTX compared with pre-PTX , and 82.86% patients underwent an improvement of left ventricular systolic function post 1year of the PTX.In all the patients (135), the main ultrasonic cardiogram parameter dramatically improved after PTX. Compared with pre-PTX, the left ventricular mass (LVM)  g vs. 192.76  g, tPTX+AT is an effective curative intervention of secondary hyperparathyroidism and can significantly overturn the LVH and increase the left ventricular systolic function. The morbidity of secondary hyperparathyroidism is high in ESRD patients. Among all the complications, cardiovascular events are the leading causes of death, and the mortality caused by cardiovascular disease (CVD) is 10 to 100 times higher than that in the general population , 3. HoweThe cohort of this retrospective study consisted of ESRD patients with SHPT received PTX from Oct 1, 2010, to Oct 1, 2016, at the First Affiliated Hospital, Zhejiang University School of Medicine. The inclusion criteria of PTX were according to Kidney Disease Improving Global Outcomes (KDIGO) 2009 guidelines 2, female) = 0.0073 × height (cm) + 0.0127 × weight (kg) -0.2106;Body surface area (BSA)  = 0.0057 × height (cm) + 0.0121 × weight (kg) + 0.0882;BSA (m2) = LVM/BSA.LVMI , LVMI≥115 g/m2  [The diagnostic criteria of left ventricular hypertrophy (LVH) are: LVMI≥95 g/m2  .The improvement of LV systolic function was defined as the improvement of the EF% measured by echocardiography to an increase of 10% or greater in its absolute value 1-year post-PTX.The primary evaluation items were: the change of ultrasonic cardiogram parameter pre- and 1-year post-PTX; the influence factor for the overturn of LVH; the influence factor for the improvement of EF%.The secondary evaluation items included the biochemical parameters change pre- and post-PTX.P < 0.05 was regarded as statistically significant.We used the Statistical Package for the Social Sciences (SPSS) version 23.0  for statistical analyses. We used Kolmogorov-Smirnov (KS) test to determine the normality of the continuous variables. Continuous variables were presented as mean ± SD or interquartile range, and categorical variables were presented as number and proportion. We used the paired t-test and Wilcoxon signed- rank sum test to check the difference between ultrasonic cardiogram parameters, LVM and LVMI, pre- and at one-year post-PTX. Moreover, We used the multiple logistic regression analysis to determine the influence factor for the overturn of LVH and the improvement of EF% one-year post-PTX. There were 293 ESRD patients diagnosed with SHPT between Oct 1, 2010, and Oct 1, 2016 received parathyroidectomy. Out of them, following patients(158) were excluded: 10 patients were excluded because of the PTH>100 ng/L within 1 month post- PTX, 8 because of receiving the kidney transplant during the follow-up, 39 because of the follow-up<1 year, 8 because of receiving the PTX due to recurrence; and 93 because of data missing or insufficiency. In total, 135 ESRD patients  with severe SHPT were included  ng/L compared with a pre-operative level of 2357.00  ng/L. The serum alkaline phosphatase increased after the PTX, reached peak level after 1 month of the PTX, and gradually declined to normal level after 1 year of the PTX. The serum albumin declined after the PTX, and increased after 3 months of the PTX significantly (Table p<0.001). Furthermore, LVMI pre- PTX was 123.54  g/m2, after 1 year of PTX, the LVMI was 107.01  g/m2 (p<0.001). The LVDd, PWd, LVDs, and IVSs also declined significantly after PTX (P<0.05). There was no statistical difference observed in EF%, FS%, LA, AO, IVSd, LVPWs as compared with those during pre-PTX  g after 1 year of PTX, while LVM was 192.76  g pre- PTX  , before the PTX, the incidence of LVH was 59.26% (80), and among them, 43.75% (35) patients recovered from LVH after 1 year of the PTX. To determine the reason for the overturn of LVH, we collected some data maybe related to the overturn of LVH including the cardiovascular drugs  used during the follow-up, and the blood pressure 1-year post-PTX, then we conducted the multiple logistic regression analyses. In the multiple logistic regression analyses, we didn’t observe the significant influence factor for the overturn of LVH (Table In patients whose EF% ≤ 60% (35), there were 82.86% (29) patients underwent an increase of 10% or greater in its EF% absolute value after 1 year of the PTX, which showed the markedly improvement of the LV systolic function. To determine why the EF% increased, we collected some data maybe related to the improvement of EF% including the cardiovascular drugs  used during the follow-up, and the blood pressure 1-year post-PTX, and then we conducted the multiple logistic regression analyses. In the multiple logistic regression analyses, we didn’t observe the significant relationship between cardiovascular drugs, blood pressure and the improvement of EF% either (Table cardiovascular disease, and sexual dysfunction [The morbidity and mortality of cardiovascular disease in dialysis patients is found significantly high, and the CVD accounts for about 50% of death in hemodialysis patients in European countries and the USA [SHPT, a common complication of ESRD, is a clinical condition associated with bone and mineral disorder, anemia, pruritus, hypertension, vascular calcification, function . The mor the USA –11. Over the USA . Some fi the USA . Several the USA , 14, 15.LVH and left ventricular diastolic dysfunction are the most common types of myocyte damage noticed in uremic patients. LVH is an adaptive response to pressure and volume overload. In dialysis patients, the incidence of LVH was reported about 68–89%, and it has been reported that LVMI increases substantially in the majority of dialysis patients who are treated with standard care, including angiotensin blockade, dialysis frequency, and anemia management , and LVMOf all the patients, 43.75% diagnosed with LVH pre-PTX recovered from LVH after 1 year of PTX in our study, and we didn’t observe the significant influence factor for the overturn of LVH post-PTX including cardiovascular drugs and blood pressure in the multiple logistic regression analysis, so it can be confirmed the impact of PTX on the overturn of LVH further.15% incidence of systolic dysfunction among newly started dialysis patients was reported, and there are case reports documenting an increase in EF% post-PTX , 21. SmaIn our study, we observed a generally rising trend in EF% and FS%, though there was no statistical difference observed in all patients. EF% was 66.69 ± 7.07% vs. 65.52 ± 7.80% and FS% was 37.01 ± 5.70% vs. 36.63 ± 5.80%. In the subgroup analysis of EF% ≤ 60% pre-PTX, we found that EF% and FS% after PTX significantly improved compared with pre-PTX and EF% level of 64.90 ± 7.90% vs. 55.71 ± 4.78%. And in these patients, 82.86% patients underwent an increase of 10% or greater in its EF% absolute value post 1 year of PTX, showing the markedly improvement of the LV systolic function. And in the multiple logistic regression analysis, we didn’t observe the significant relationship between the cardiovascular drugs, the blood pressure and the improvement of EF%, so we can affirm the effect of PTX on the improvement of the left ventricular systolic function. Compared with N Goto’s study, we conducted a longer and more comprehensive study.By comparing our findings with previous ones, we conclude that the left ventricular function improved in ESRD patient after the PTX might be related to the causes, such as the decline of PTH after the PTX reduced or even overturned the damage of myocardium and ameliorated arterial calcification; the improvement of serum calcium and phosphorus abnormal also alleviated the vascular calcification; the improvement of nutrition status after the PTX was conducive to the recovery of the myocardium; PTX could improve blood pressure, with the better control of blood volume, the afterload declined, but in our study, the effect of BP didn’t observe in multiple logistic regression analysis.tPTX+AT is an effective curative intervention of secondary hyperparathyroidism and can significantly overturn the LVH and increase the left ventricular systolic function.Our study has some limitations: this is a single-center retrospective study, and we could not set randomize control group, which makes the study rigorous enough; the sample capacity was not large, especially the subgroup; the confounding bias interference factors were not excluded thoroughly.


Apnea–hypopnea index (AHI and desaturation index (ODI) were identified as independent predictors for UACR and eGFR, respectively. Therefore, in patients with DKD under optimized treatment, severe OSA is associated with a higher UACR and a lower eGFR, reflecting an additional contribution to the impairment of their renal function, although no causality can be inferred.Obstructive sleep apnea (OSA) is a recognized risk factor for the development of diabetic kidney disease (DKD). Our objectives were to compare the urinary albumin–creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) of patients with DKD according to OSA severity, and to evaluate the contribution of sleep parameters to their renal function. In a multicenter, observational, cross-sectional study, 214 patients with DKD were recruited. After a sleep study, UACR and eGFR were measured, as well as serum creatinine, fasting glucose, glycated hemoglobin, insulin resistance, lipid profile and C-reactive protein. UACR was higher in severe OSA patients (920 ± 1053 mg/g) than in moderate  or mild OSA/non-OSA subjects . At the same time, eGFR showed an OSA severity-dependent reduction (48 ± 23 vs. 59 ± 21 vs. 73 ± 19 ml/min per 1.73 m Progressive evidence shows that OSA is associated with impaired glucose tolerance, insulin resistance and increased risk of developing type 2 diabetes5. Furthermore, OSA could aggravate the evolution of diabetes, since it has an adverse effect on glycemic control7.Obstructive sleep apnea (OSA) and type 2 diabetes are common diseases. It has been estimated that 936 million adults around the world have mild to severe OSA9. Although there are some conflicting results12, studies conducted in type 2 diabetes patients  have shown that mild to severe OSA (defined by an apnea–hypopnea index (AHI) ≥ 5/h) is associated with a higher prevalence of DKD, while also reporting a relationship between AHI and albuminuria16. The longitudinal analysis of a cohort of type 2 diabetes patients has even identified that the presence of OSA is associated with greater deterioration of the estimated glomerular filtration rate (eGFR)17. Thus, there is moderate evidence that OSA may be a risk factor for the development of DKD18.Among the main consequences of the progression of diabetes, diabetic kidney disease (DKD) deserves special consideration. This frequent diabetic microvascular complication is the main type of chronic kidney disease and the leading cause of renal failure and dialysis worldwide19. Therefore, there is a need for new approaches that would allow the identification of additional risk factors to progression of DKD. Until now, OSA has been shown to be a risk factor for cardiovascular events and mortality in dialysis patients20, and several factors have linked OSA with the development and progression of chronic kidney disease, including diabetes mellitus, hypertension, arterial stiffness, proteinuria and obesity21. However, to our knowledge, information about the effect of OSA on the control of patients with an already established DKD is scarce or non-existent.Although treatment of DKD has slowed the rate of progression to end-stage renal disease, treatment costs are very high and do not prevent a high death rateTherefore, our objective has been to compare the kidney function impairment, assessed in terms of urinary albumin–creatinine ratio (UACR) and eGFR, of patients with a previous diagnosis of DKD adequately treated according to conventional guidelines, based on the severity of associated OSA. We also intend to evaluate the contribution of sleep parameters to UACR and eGFR in these patients.Table According to Epworth sleepiness scale, daytime hypersomnia reported in our study was mild in 116 patients (59.5%), moderate in 54 (27.7%) and severe in 4 (2.1%), with a overall score of 7 (4–9). The AHI was 30.0 (17.9–46.2)/h, with a desaturation index of 31.3 (19.3–47.9)/h and a predominance of obstructive events (94 ± 11%). During the 30.3 (10.9–53.8)% of the recording time, the patients had oxygen saturation less than 90%, with a mean and a low nocturnal oxygen saturation of 91 (89–92) and 77 (69–82)%, respectively. According to conventional criteria, OSA was identified in 212 patients, which was mild in 36 cases (16.8%), moderate in 65 (30.4%) and severe in 111 (51.9%).The comparison of patients with DKD without OSA or with mild OSA versus those with moderate OSA or severe OSA only showed a slight difference in age and BMI, which were both greater in severe OSA patients. There were no differences between the three groups in other anthropometric characteristics, smoking, time of evolution of diabetes or DKD, blood pressure, comorbidity, level of daily physical activity or current treatment Table .In addition to the evident differences in daytime sleepiness and sleep parameters according to the presence and severity of OSA Table , differe2 , mean nocturnal SaO2  and low nocturnal SaO2 , while the QUICKI index did so with tSaO2 < 90%  and lowest nocturnal SaO2 . In turn, serum levels of hsCRP were related to AHI , mean nocturnal SaO2  and low nocturnal SaO2 .Overall, the UACR in patients with DKD was directly related to the Epworth sleepiness scale, AHI and the desaturation index, while it maintained an inversely proportional relationship with low nocturnal SaOe 2 Fig. . In contFinally, the multiple linear regression model adjusted for age, sex, BMI, fat mass index, duration of diabetes, smoking status, systolic and diastolic blood pressures, HbA1c, cholesterol, HDLc, LDLc, triglycerides, and treatment with insulin, ACEi, ARB or MRA drugs only retained AHI as an independent predictor of the UACR . With regard to eGFR, the multiple linear regression model adjusted for the same variables only retained the desaturation index as an independent determinant   than non-apneic patients or those with mild OSA. Furthermore, we have identified that, in this group of patients, AHI is an independent determinant of UACR, while desaturation index is an independent determinant of eGFR.22. These results could relatively agree with those obtained by Tahrani et al.17, who identified a prevalence of OSA of 79% among the 90 patients in their study who had DKD, despite having a lower prevalence of males, the patients being a decade younger and having a shorter diabetes evolution time. Interestingly, this study also found a notable discrepancy in the prevalence of OSA according to the ethnic group of patients with DKD, ranging from 89% in white Europeans to 67% in Southern Asians17. Similarly, in 880 Chinese type 2 diabetes patients hospitalized for poor glycemic control, microvascular complications, cerebrovascular complications, cardiovascular complications or infection, the prevalence of OSA was 9% in the 11% who had a previous history of DKD14. In addition to the ethnic differences compared to our patients, this study also recruited a higher percentage of women who were younger, had a lower BMI and had a shorter duration of diabetes. In any case, it is also necessary to highlight that our study may slightly overestimate the prevalence of OSA in patients with DKD because we have selected overweight or obese patients, in whom this disorder is more prevalent.One prominent finding is the high prevalence of OSA in our patients with DKD, but with little impact on sleep-related symptoms since the average score of the Epworth sleepiness scale was 7, and only 29.8% reported moderate to severe sleepiness, as usually happens in studies performed in patients not directly referred to a sleep unit23. In fact, eGFR and albuminuria have been shown to be independent predictors of renal outcomes in patients with DKD, whereas cardiovascular end-points are more dependent on age, HbA1c or phosphorus level24. The relevance of UACR and eGFR is confirmed in classic studies that identify them, together with pathological grade, as prognostic factors for the progression of DKD to end-stage renal disease25.The selection of UACR and eGFR as indicators for the severity of DKD was due to their easy determination and universal access, in addition to being proven predictors of renal prognosis and not so much of cardiovascular prognosis, which seems more dependent on glycemic control and, therefore, appears to be less specific for renal involvement in diabetes26. Similarly, other studies have also described that the desaturation index is a risk factor for the development of DKD28. However, our results are in contrast with the finding of Leong et al.13, who identified that the tSaO2 < 90% was related to the eGFR of patients with type 2 diabetes with or without DKD. When the former are specifically analyzed, as has been our case, the tSaO2 < 90% does not reach any correlation with the UACR or the eGFR.Although to our knowledge there is no exclusive information on patients with DKD, the identification of differences in UACR and eGFR based on the severity of OSA, stratified by AHI, coincides with previous studies in which this parameter has been identified as a risk factor for the development of albuminuria in patients with type 2 diabetes30. Secondly, the influence of AHI and the oxygen desaturation index on renal function variables instead of tSaO2 < 90% or median nocturnal SaO2 indicates that the impact of OSA is due to sleep fragmentation and/or hypoxia-reoxygenation episodes and not so much the maintenance of sustained hypoxemia during the night.In general, we consider that our findings have two clinical-pathogenic implications in the effect of OSA on DKD. First, they highlight that the impact is limited to patients with severe OSA and, to a lesser extent, moderate OSA. This finding provides a dimension of the problem that is more consistent with the prevalence of both entities and with the identification of risk groups. It also coincides in the need to identify AHI cut-off points higher than 5 to select patients with higher cardiovascular risk12. Of all of them, the absence of a relationship between UACR and eGFR with HbA1c or SBP is particularly relevant, which are clearly altered parameters in patients with OSA. This poses the attractive hypothesis that OSA could worsen albuminuria or eGFR, regardless of poor glycemic control and high blood pressure, through the involvement of other pathogenic mechanisms.Another outstanding finding of our study is the verification that in the UACR or eGFR prediction models, the AHI or the desaturation index displace classic risk factors for a poor renal prognosis in patients with DKD, such as age, BMI, duration of diabetes or DKD, systolic blood pressure (SBP), HbA1c or presence of DKD32. In addition to promoting the development of hypertension33, which seems not to be related to the renal function of our patients, this can also lead to tubulointerstitial injury34 and renal fibrosis35, causing proteinuria and decreased eGFR31. Moreover, sympathetic activation may also increase angiotensin II, leading to efferent arteriolar vasoconstriction and hyperfiltration, which is a key pathway for the progression of chronic kidney disease36. Second, OSA with concurrent type 2 diabetes is associated with increased oxidative and nitrosative stress and activation of the inflammatory pathways, impairing microvascular and endothelial regulation32. These induce damage in vulnerable endothelial and mesangial cells and peripheral nerves, which may promote the kidney damage38. Moreover, OSA-related reactive oxygen species and systemic inflammation contribute to atherosclerosis31 and may also contribute to chronic kidney disease progression32. And finally, OSA could induce intermittent intra-renal hemodynamic changes. Moreover, recurrent sympathetic overactivity due to sleep fragmentation also can cause intermittent intra-renal hemodynamic changes that induce ischemia and reperfusion injury, promoting the intrinsic renal damage39. In fact, in a case report on OSA that showed secondary focal glomerulosclerosis, proteinuria improved completely after treatment with bi-level positive airway pressure40. Moreover, patients with untreated OSA have a lower renal plasma flow and a higher filtration fraction compared to treated patients41.Although our study does not intend to evaluate pathogenic pathways, in a purely speculative way it could be stated that several OSA-related pathophysiologic changes might influence glomerular endothelial function and urinary albumin excretion in patients with DKD through various pathways. First, sleep fragmentation activates the sympathetic nervous system and the renin–angiotensin–aldosterone systemOur study has several strengths. It is a multicenter study that specifically evaluates patients who already have established DKD, using proven indicators for kidney damage. In addition, the finding of the discriminative capacity of AHI in patients who have optimized treatment according to conventional guidelines identifies a new possible therapeutic target on which to act.42. Fourth, our study population was exclusively Caucasian European, so its extrapolation to other ethnic groups should be done with caution.However, we also admit to certain limitations. First of all, this is a study with a cross-sectional design, therefore a causal relationship between OSA and renal function impairment cannot be definitively established. Second, a central laboratory has not been used for analytical determinations or sleep studies. We opted for local analyses performed at each study center to better reflect a situation of daily clinical practice, while also taking into account the fact that the use of both procedures is practically universal. Although this may detract from our results, we believe that it could increase their external validity. Third, as in most previous studies, the UACR was determined from one urine sample rather than three different samples, as prior studies have shown that a single measurement is accurate for assessing the degree of nephropathy and is therefore sufficient for clinical or epidemiological studiesIn conclusion, the presence of severe OSA in patients with DKD is associated with a higher UACR and a lower eGFR, reflecting a greater severity of renal involvement. Furthermore, in patients with optimized treatment, AHI and oxygen desaturation index are selected as independent determinants of UACR and eGFR, which raises the possibility of identifying a new therapeutic target on which to act in these patients to prevent their progression to end-stage renal disease.2), previous diagnosis of type 2 diabetes  > 6.5%) and diabetic kidney disease . Moreover, patients were on stable diabetes treatment, and angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARB) or aldosterone receptor antagonists (MRA) were used at a recommended therapeutic dose for at least 4 weeks.A multicenter, observational cross-sectional study was conducted in six teaching hospitals in Spain. Patients were consecutively selected according the following criteria: age between 18 and 80 years old, overweight or obese ; acute coronary syndrome, stroke, transient ischemic attack, or hospitalization for heart failure worsening within the previous 30 days; type 1 diabetes or known non-diabetic renal disease; evidence of bilateral renal artery stenosis; systolic blood pressure ≥ 180 mmHg or diastolic blood pressure ≥ 110 mm Hg. Dialysis for acute renal failure within the 6 previous months, continuous treatment with non-steroidal anti-inflammatory drugs, treatment with high doses of acetylsalicylic acid (> 500 mg/day), or previous treatment with CPAP were considered additional exclusion criteria.The study was approved by the Institutional Ethics Committee of the Hospital Universitario La Paz, Madrid, Spain (number of protocol: PI-2386), and all subjects gave their written informed consent. All methods were performed in accordance with the relevant guidelines and regulations.43. All medications used by the participants at the time of the sleep test were listed.Anthropometric characteristics were measured, including neck circumference and waist–hip ratio as well as body composition . Based on self-administered questionnaires and medical records, duration of diabetes, DKD, smoking status and comorbidities were recorded. ‘Smokers’ were defined as subjects who currently smoked more than ten cigarettes per day. Past smokers who had quit smoking were not considered smokers in this study. Aged-adjusted Charlson comorbidity index was calculated44 and the International Physical Activity Questionnaire (iPAQ)45 were used to assess baseline sleepiness and daily physical activity, respectively.Three consecutive heart rate and blood pressure readings were obtained with an automatic device in the seated position after the subjects had rested for at least 5 min. The Epworth sleepiness scale2)46. Sleep studies with < 4 h of adequate recordings were repeated and excluded if the quality remained poor. All readings and scoring were conducted manually by experienced, trained personnel. Apnea was defined as an interruption of oronasal flow of > 10 s; presence or absence of thoracic and abdominal movements made a distinction between central and obstructive events, respectively47. Hypopnea was defined as a 30–90% reduction in oronasal airflow for > 10 s, associated with oxygen desaturation ≥ 3%47. AHI was defined as the number of apneas plus hypopneas per hour of recording, while tSaO2 < 90% was defined as the percentage of recording time with SaO2 < 90%. In addition, mean saturation, lowest saturation and oxygen desaturation index (ODI) were measured. According to AHI, patients were classified as non-OSA (< 5/h), mild OSA (5–14.9/h), moderate OSA (15–29.9/h) or severe OSA (≥ 30/h)48.All patients underwent overnight respiratory polygraphy with validated portable devices providing continuous recording of oronasal flow and pressure, thoracic and abdominal respiratory movements, heart rate and arterial oxygen saturation , and creatinine was measured by a kinetic colorimetric assay. Microalbuminuria was defined as UACR > 30 mg/g, and macroalbuminuria was defined as > 300 mg/g. The coefficients of reproducibility for the UACR measurement were 2% intra-assay, 6% interassay and 12% intraindividual in our laboratory. Urine samples with evidence of urinary tract infection were repeated when free from infection.cr/κ, 1)α × max−1.209 × 0.993Age × 1.018 [if female], where: Scr is serum creatinine in mg/dl, κ is 0.7 for females and 0.9 for males, α is − 0.329 for females and − 0.411 for males, min indicates the minimum of Scr/κ or 1, and max indicates the maximum of Scr/κ or 149. HbA1c was determined using a high-performance liquid chromatography method certified by the National Glycohemoglobin Standardization Program (NGSP). Fasting glucose and insulin levels were also measured and, in noninsulin users, Homeostasis Model Assessment-Insulin Resistance (HOMA-IR)50 and Qualitative Insulin Sensitivity Check Index (QUICKI) scores51 were calculated. Finally, total cholesterol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triglycerides and high sensitivity C-reactive protein (hsCRP) were determined at the different participating hospitals using standard enzymatic methods.Serum creatinine was measured by photometric method, and eGFR was calculated using the Chronic Kidney Disease Epidemiology (CKD-EPI) creatinine equation: eGFR = 141 × min, depending on their distribution, while categorical variables are reported as absolute numbers and percentages. Normality in the distribution of the data for each variable was explored using Kolmogorov–Smirnov and Shapiro–Wills tests. Differences between groups were analyzed by the chi-square test or Fisher exact test , Kruskal–Wallis test  and ANOVA with post-hoc comparisons by the Bonferroni test .p < 0.05) the fraction of explained variability (r2). Changes in the distribution of the residuals, residual standard deviation, and the homogeneity of the variance over the predictors were also explored. All statistical tests were two-sided and statistical significance was assumed for p < 0.05. Statistical Package for the Social Sciences, version 26.0 software  was employed.To assess relationships between variables, non-normal variables were log transformed and Spearman correlation test was used. Significant contributors to UACR or eGFR were introduced in a forward stepwise multiple linear regression analysis to identify independent determinants. In this analysis, predictor variables were retained only if their addition significantly improved (