5404131
How can we prevent intradialytic hypotension?
PURPOSE OF REVIEW
Intradialytic hypotension (IDH) produces uncomfortable symptoms for the patient and reduces the efficiency of dialysis.


RECENT FINDINGS
IDH may be an important cause of vascular access thrombosis. Automatic biofeedback-controlled dialysis changes dialysate conductivity and ultrafiltration during dialysis. A number of trials suggest that automatic feedback-controlled dialysis improves IDH in part by improvement in myocardial stunning and preservation of cardiac function. However, the effects of automatic biofeedback dialysis are inconsistent between studies and sample sizes are small. Acetate even in small amounts may trigger IDH especially in predisposed patients. Cool temperature dialysate causes vasoconstriction, activates the sympathetic nervous system, preserves central blood volume, and mitigates IDH. Increasing the treatment time to at least 4 h three times a week and limiting dialysate and dietary sodium intake are effective ways to reduce IDH. Ultrafiltration profiling needs further work, but it appears that removing more fluid during the first hour of dialysis and reducing the rate later on may also reduce IDH.


SUMMARY
Adequate prescription and frequency of dialysis treatments, limiting dietary and dialysate sodium, ultrafiltration profiling, automatic biofeedback-controlled dialysis, avoidance of acetate, and cool temperature dialysate may be effective strategies to reduce IDH.
22176722
Alar web in cleft lip nose deformity: study in adult unilateral clefts.
BACKGROUND
The correction of alar webbing in unilateral cleft lip nose deformity is challenging because of progressive distortions in the alar web region during the period of growth. Alar webbing is a persistent universal deformity in both the primary and secondary cleft lip noses. The purpose of this article is to study the alar web deformity in adult patients with unilateral cleft lip noses.


METHODS
Twenty-five patients aged 13 years and older presenting with unilateral cleft nasal deformity were included. Preoperative and postoperative measurements of the nose, along with detailed intraoperative recording of the deformed anatomy, were done. Preoperative magnetic resonance imaging was also done in selected cases. Transcolumellar open rhinoplasty was performed in all the cases, and nasal septal straightening with centralization was done. Cleft alar base augmentation was done using bone graft to restore symmetry of the nasal tripod. Both the cleft and noncleft alar cartilages were extensively mobilized from the skin and mucosal sides. The overgrown and caudally slumped cleft-side alar cartilage was resected caudally and was then resuspended in a symmetrical position with the noncleft alar cartilage. A midline-strut septal cartilage extension graft was used to restore the tip aesthetics. The skin overlying the alar web was in-rolled after semilunar cartilage resection, and skin excision was also done to restore symmetry with the opposite vestibule. The remaining secondary cleft nasal and lip deformities were corrected depending upon the specific presenting pathologic abnormality.


RESULTS
The cleft alar cartilage was found to be caudally displaced in all the cases. The caudal border of the lateral crus was prolapsing in the cavity of the vestibule on the superomedial aspect and was tenting the skin in the area of the weak triangle, producing the characteristic alar web deformity. In the study group, the maximum width of the cleft alar cartilage at the level of the lateral crus was increased by approximately 4 mm when compared with the noncleft alar cartilage. The before- and after-rhinoplasty surgery results were objectively assessed using a patient, surgeon, and independent observer survey. The cosmetic result of the nasal tip complex was found to be very good and good (90%), satisfactory (5%), and poor (5%) in patients.


CONCLUSIONS
The alar web in unilateral cleft lip nose deformity is the result of caudal overgrowth and migration of the alar cartilage. The caudal edge of the prolapsed lateral crus overhangs the cleft-side nasal aperture on its superomedial aspect, producing this deformity. Satisfactory correction of this deformity should envisage caudal resection and repositioning of the dislocated alar cartilage along with caudal resection of the lateral crus with in-rolling of the skin after resection to achieve symmetric results in unilateral cleft lip rhinoplasty.
24249726
Regulation of circadian blood pressure: from mice to astronauts.
PURPOSE OF REVIEW
Circadian variation is commonly seen in healthy people; aberration in these biological rhythms is an early sign of disease. Impaired circadian variation of blood pressure (BP) has been shown to be associated with greater target organ damage and with an elevated risk of cardiovascular events independent of the BP load. The purpose of this review is to examine the physiology of circadian BP variation and propose a tripartite model that explains the regulation of circadian BP.


RECENT FINDINGS
The time-keeper in mammals resides centrally in the suprachiasmatic nucleus. Apart from this central clock, molecular clocks exist in most peripheral tissues including vascular tissue and the kidney. These molecular clocks regulate sodium balance, sympathetic function and vascular tone. A physiological model is proposed that integrates our understanding of molecular clocks in mice with the circadian BP variation among humans. The master regulator in this proposed model is the sleep-activity cycle. The equivalents of peripheral clocks are endothelial and adrenergic functions. Thus, in the proposed model, the variation in circadian BP is dependent upon three major factors: physical activity, autonomic function, and sodium sensitivity.


SUMMARY
The integrated consideration of physical activity, autonomic function, and sodium sensitivity appears to explain the physiology of circadian BP variation and the pathophysiology of disrupted BP rhythms in various conditions and disease states. Our understanding of molecular clocks in mice may help to explain the provenance of blunted circadian BP variation even among astronauts.
191311
Assessment of iothalamate plasma clearance: duration of study affects quality of GFR.
BACKGROUND AND OBJECTIVES
Measurement of GFR is important for the management of chronic kidney disease (CKD). Although bolus administration of radiocontrast agents is commonly used to measure GFR, the optimal duration of sampling to assess their plasma clearance is unknown. The purpose of this study was to evaluate whether the duration of plasma sampling influences precision and estimation of GFR.


DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS
GFR was measured by sampling plasma 12 times over 5 h in 56 patients with CKD (mean age 64 yr, 98% men, 79% Caucasian, 34% diabetics, estimated GFR 31.8 +/- 14.2 ml/min/1.73 m(2)). In a subset of 12 patients we measured GFR by sampling plasma 17 times over 10 h.


RESULTS
Short sampling intervals considerably overestimated GFR measured using total plasma iothalamate clearance, especially in larger patients. In the higher estimated GFR group (>30 ml/min/1.73 m(2)), the 5-h GFR was 17% higher and 2-h GFR 54% higher compared with the 10-h GFR, which averaged 40.3 ml/min/1.73 m(2). In the lower estimated GFR group (<30 ml/min/1.73 m(2)), the 5-h GFR was 36% higher and 2-h GFR 126% higher compared with the 10-h GFR, which averaged 22.2 ml/min/1.73 m(2). Short sampling duration also reduced the precision of the estimated GFR from 1.67% for 10-h GFR, to 3.48% for 5-h GFR, and to 7.07% for 2-h GFR.


CONCLUSIONS
GFR measured over a longer duration with multiple plasma samples spanning the distribution and elimination phases may improve precision and provide a better measure of renal function.
11453581
Proinflammatory effects of oxidative stress in chronic kidney disease: role of additional angiotensin II blockade.
Oxidative stress plays an important role in causing progressive chronic kidney disease (CKD). We examined the influence of add-on ANG II receptor blockade administered as losartan (50 mg/day for 1 mo) on oxidative stress and proinflammatory state of the kidney in patients with CKD. All subjects were taking an angiotensin-converting enzyme inhibitor plus other antihypertensive agents. Oxidative stress to lipids and proteins was measured by an HPLC assay for malondialdehyde (MDA) and carbonyl concentration, respectively. Urinary inflammation was measured by monocyte chemotactic protein-1 (MCP-1) excretion rate. The etiology of CKD was type 2 diabetes mellitus in 12 and glomerulonephritis in 4 patients. There was no change in proteinuria or 24-h ambulatory blood pressure (BP) with add-on ANG II receptor blockade with losartan therapy. Before losartan therapy, urinary protein and albumin oxidation were 99 and 71% higher, respectively, compared with in plasma (P < 0.05). There was a 35% reduction in urinary oxidized albumin with add-on losartan therapy (P = 0.036). Urinary and plasma MDA were elevated compared with age-matched controls. Urinary MDA was significantly reduced from 4.75 +/- 3.23 to 3.39 +/- 2.17 micromol/g creatinine with add-on losartan therapy. However, plasma MDA or oxidized proteins did not change in response to additional ANG II blockade. A good correlation was seen between the change in urinary oxidized albumin and MCP-1 levels (r = 0.61, P = 0.012). These data demonstrate that oxidative damage to urinary protein and lipids can be reduced with additional ANG II receptor blockade, independently of reductions in proteinuria or BP. Urinary measurements of markers of oxidative damage to lipids and proteins appear to be more sensitive than plasma measurements in patients with CKD. The significant association of the change in urinary MCP-1 with a reduction in oxidative stress supports the role of the redox state in the kidney with renal fibrosis and progressive kidney damage.
36005104
Volume Overload in Dialysis: The Elephant in the Room, No One Can See
interests of the authors. However, considering the totality of the evidence, I am less convinced that this marker is superior to other volume markers. First, there are few head-to-head studies comparing BIA to other established markers of volume. Second, there is no range that defines ‘normal’. Unlike blood pressure (BP) or cholesterol, there is no target that has been established. The normal values are obtained from healthy subjects whose body composition differs substantially from those on dialysis. Extrapolating from healthy subjects to those with ESRD on hemodialysis does not appear scientifically valid. Third, there is no study to my knowledge that demonstrates convincingly that compared to probing dry weight without BIA, BIA-guided dry weight reduction results in improved outcomes. Most data provided to support the use of BIA are associative and observational. A large amount of observational data does not prove causation. We therefore have to be cautious in interpreting these data as ‘strongly indicative of fluid overload’. Nearly all markers of volemia suffer from the same shortcomings. These shortcomings include lack of normative data, and data being largely observational and associative in nature. As an example, several observational studies suggest that B-type natriuretic peptide (BNP), NT-proBNP or other natriuretic peptides are associated with volume state among people with ESRD on dialysis [2–10] . However, only one study has been reported to date that relates the change in BNP to an intervention of probing dry weight [11] . In this study, a direct relationship existed at baseline between BNP and interdialytic ambulatory BP. Since interdialytic ambulatory BP is reVolume overload is the invisible threat to the health of dialysis patients. Currently, Medicare incentivizes the measurement of the dose of dialysis (urea reduction ratio) but has no measure of volume. Perhaps this is because the few who can recognize the epidemic nature of volume excess cannot agree on how to define it. Whereas, some have proposed interdialytic weight gain (IDWG) as a marker of volume, the in-depth review of Hecking et al. [1] quite clearly and importantly makes the distinction that IDWG should not be confused with hypervolemia. One has to wonder how IDWG got confused with dry weight in the first place. It appears that epidemiologists decided to use IDWG as a proxy of dry weight because of its ready availability in large databases. IDWG is a marker that is convenient; it can be measured easily and it can be related to outcomes such as all-cause mortality. This analysis was performed and a relationship emerged between IDWG and all-cause mortality. But establishing a relationship between IDWG and mortality does not establish causality. It could be numerous other factors, measured and unmeasured, associated with IDWG which may be causally related to mortality. Factors such as missing or cutting short dialysis, not taking medications as prescribed, and consuming a diet rich in phosphorus and potassium are some confounding factors that may also be associated with IDWG but may be more plausibly related to mortality. The authors discuss several markers of volume excess. Although several exist, one marker, bioimpedance analysis (BIA), is discussed in great detail. This is understandable given both the academic and intellectual property Published online: July 6, 2013 Nephrology American Journal of
6766565
Case 3-2007: a boy with respiratory insufficiency.
n engl j med 356;22 www.nejm.org may 31, 2007 2329 To the Editor: In the Case Record of a patient with respiratory insufficiency, presented by Boyer et al. (Jan. 25 issue),1 the discussants do not mention a condition known to be associated with idiopathic pulmonary hemosiderosis and to have implications for its management: celiac disease. The association is referred to as the Lane–Hamilton syndrome.2 It is important to recognize this condition, since treatment of celiac disease with a gluten-free diet could lead to the remission of idiopathic pulmonary hemosiderosis.3 Although both celiac disease and idiopathic pulmonary hemosiderosis are believed to be immunologically mediated, the pathogenetic link between them is not clear. A recent systematic review identified 20 patients with the Lane–Hamilton syndrome.4 Of these, 16 had been prescribed a gluten-free diet, with improvement documented in 12. Patients with idiopathic pulmonary hemosiderosis should be screened for celiac disease, even in the absence of gastrointestinal symptoms, by means of serologic testing for antiendomysial antibodies. If the test is positive, an intestinal biopsy should be carried out to confirm the disease, because a gluten-free diet is very effective for the regression of both celiac disease and idiopathic pulmonary hemosiderosis.
22690717
Photodynamic therapy of chemically- and ultraviolet B radiation-induced murine skin papillomas by chloroaluminum phthalocyanine tetrasulfonate.
Photodynamic therapy (PDT) of cancer combines irradiation of tumors with visible light following selective uptake of the photosensitizer by the tumor cells. PhotofrinR-II (Pf-II) is the only photosensitizer which is in clinical use in PDT, whereas chloroaluminum phthalocyanine tetrasulfonate (AlPcTS) has also shown promise in preclinical studies. In most such studies, the effectiveness of the photosensitizers has been assessed in implanted tumor model systems rather than in model systems where tumors are allowed to grow in their own connective tissue matrix. In this study the pharmacokinetics, tumor ablation capability and cutaneous photosensitization response of AlPcTS have been assessed in mice bearing chemically- and ultraviolet B radiation (UVB)-induced benign skin papillomas. When tumor-bearing animals were injected intraperitoneally with AlPcTS (5 mg/kg body wt), maximum tumor:normal skin ratio of 2.4 was observed at 48 h, at which time the mice were irradiated within the absorption spectrum of the photosensitizer. In tumor ablation studies with SENCAR mice bearing chemically-induced skin tumors, AlPcTS resulted in greater than 80% ablation in tumor volume at 20 days post-irradiation. In cutaneous photosensitization response, AlPcTS produced only transient effects (no effect after 24 h) in SENCAR mice. Pharmacokinetics data, tumor ablation effects and cutaneous photosensitization response of AlPcTS were comparable in SKH-1 hairless mice bearing UVB-induced skin tumors. Our data indicate that AlPcTS produces significant photodynamic effects towards the ablation of murine skin tumors, and that it does not produce prolonged cutaneous photosensitivity.
39024721
Efficacy and safety of iodopovidone in chemical pleurodesis: a meta-analysis of observational studies.
The search for an 'ideal' agent for pleurodesis continues. Iodopovidone is a topical antiseptic and has been shown to be safe and effective in many studies. The aim of this study was to evaluate the efficacy and safety of iodopovidone as an agent for chemical pleurodesis. We performed a systematic review of all the observational trials which have used iodopovidone for chemical pleurodesis. Six studies including 265 patients who had undergone chemical pleurodesis with iodopovidone were included for this analysis. Iodopovidone was used for variety of indications, which included pleural effusion (157 patients), and pneumothorax (108 patients). Pleurodesis was performed through tube thoracostomy in 144 patients and through thoracoscopy in 121 patients. The success rate of pleurodesis varied from 64.2% to 100%, and summary success rate of all the studies was 90.6% (95% confidence intervals [CI], 86.4-93.8). The success rate was independent for the procedure (tube thoracostomy [126/144; 87.5%, 95% CI 80.9-92.4] or thoracoscopy [114/121; 94.2%, 95% CI 88.4-97.6]) used for performing pleurodesis or for the indication (pleural effusion [139/157; 88.5%, 95% CI 82.5-93.1] or pneumothorax [101/108; 93.5%, 95% CI 87.1-97.4]). The only significant complication reported was chest pain of varying degree. Systemic hypotension was reported in three patients in only one study. There were no deaths related to chemical pleurodesis with iodopovidone. Overall, this review supports the safety and efficacy of iodopovidone as an agent for chemical pleurodesis in cases of recurrent pleural effusions and pneumothoraces regardless of their etiology.
10671348
Structural analysis of botulinum neurotoxin serotype F light chain: implications on substrate binding and inhibitor design.
The seven serologically distinct Clostridium botulinum neurotoxins (BoNTs A-G) are zinc endopeptidases which block the neurotransmitter release by cleaving one of the three proteins of the soluble N-ethylmaleimide-sensitive-factor attachment protein receptor complex (SNARE complex) essential for the fusion of vesicles containing neurotransmitters with target membranes. These metallopeptidases exhibit unique specificity for the substrates and peptide bonds they cleave. Development of countermeasures and therapeutics for BoNTs is a priority because of their extreme toxicity and potential misuse as biowarfare agents. Though they share sequence homology and structural similarity, the structural information on each one of them is required to understand the mechanism of action of all of them because of their specificity. Unraveling the mechanism will help in the ultimate goal of developing inhibitors as antibotulinum drugs for the toxins. Here, we report the high-resolution structure of active BoNT/F catalytic domain in two crystal forms. The structure was exploited for modeling the substrate binding and identifying the S1' subsite and the putative exosites which are different from BoNT/A or BoNT/B. The orientation of docking of the substrate at the active site is consistent with the experimental BoNT/A-LC:SNAP-25 peptide model and our proposed model for BoNT/E-LC:SNAP-25.
45018613
Noninvasive ventilation in acute neuromuscular respiratory failure due to myasthenic crisis: case report and review of literature
A 30 year old male, a follow up case of myasthenia gravis, presented to the Emergency Department with complaints of sore throat, followed by increasing weakness in both the upper limbs and lower limbs. He also gave history of worsening bulbar weakness and progressive dyspnea on exertion. Two years ago the patient had undergone thymectomy. However, following thymectomy, the patient had minimal improvement in symptoms and was continued on glucocorticoids and pyridostigmine. Presently he was on prednisolone 30 mg/day and pyridostigmine 60 mg six times a day. On examination, he was conscious and afebrile with a pulse rate of 96 beats/minute, blood pressure 110/80 mm Hg and respiratory rate of 26/minute. Neurological examination revealed ptosis, dysphonia, bilateral asymmetric extra-ocular muscle weakness, and bifacial weakness. He had a single breath count of 10 and a breath holding time of 12 seconds. Pulse oximetry revealed a saturation of 87% breathing room air. Arterial blood gases were performed, which confirmed hypercapnic respiratory failure (pH 7.3, PaO2 6.9 kPa, PaCO2 6.7 kPa, HCO3 26 mEq/L). The patient was started on supplemental …