Triclosan (TCS) is a broad spectrum antibacterial agent present as an active ingredient in some personal care products such as soaps, toothpastes and sterilizers. It is an endocrine disrupting compound and its increasing presence in water resources as well as in biosolid-amended soils used in farming, its potential for bioaccumulation in fatty tissues and toxicity in aquatic organisms are a cause for concern to human and environmental health. TCS has also been detected in blood, breast milk, urine and nails of humans. The significance of this is not precisely understood. Data on its bioaccumulation in humans are also lacking. Cell based studies however showed that TCS is a pro-oxidant and may be cytotoxic via a number of mechanisms. Uncoupling of oxidative phosphorylation appears to be prevailing as a toxicity mechanism though the compound’s role in apoptosis has been cited. TCS is not known to be carcinogenic per se in vitro but has been reported to promote tumourigenesis in the presence of a carcinogen, in mice. Recent laboratory reports appear to support the view that TCS oestrogenicity as well as its anti-oestrogenicity play significant role in cancer progression. Results from epidemiological studies on the effect of TCS on human health have implicated the compound as responsible for certain allergies and reproductive defects. Its presence in chlorinated water also raises toxicity concern for humans as carcinogenic metabolites such as chlorophenols may be generated in the presence of the residual chlorine. In this paper, we carried out a detailed overview of TCS pollution and the implications for human and environmental health. Triclosan (TCS) is a broad-spectrum antimicrobial agent in some personal care products such as soap, sanitizer and skin cream (Kirk–Othmer ow = 4.8 octanol–water partition coefficient) suggests bioaccumulation in fatty tissues which raises toxicity concern.Structurally, TCS molecule possesses functional groups for both phenol  phenol) and ether  Fig. . Its lipThe hormonal activity of TCS  in humans pyrene, acetaminophen and bisphenol A in human liver microsomes  and partial inhibition of enoyl reductase of FAS 1 reactions  are not designed to remove pharmaceuticals or EDs; rather removals are based on the physical and chemical properties of the compounds. The efficiency of WWTPs is measured using parameters, such as biochemical oxygen demand (BOD) and chemical oxygen demand (COD), which do not take into account ED removal. During sewage treatment, EDs are only partially removed and are therefore frequently detected in WWTP effluents -β-D-xylopyranoside, 2-O--β-D-glycopyranoside, and 2,4-dichlorophenol whereas Pycnoporus cinnabarinus converts TCS into 2,4,4′-trichloro-2′-methoxydiphenyl ether and 2-O--β-D-glycopyranoside   by microbial activity Bester . The finSludge is the final destination of both TCS and its primary metabolite, MCS. Reported TCS concentrations in sludges from different plants in Germany were from 1.4 µmol to 30.4 µmol/kg Bester  while thSoil samples from ten agricultural sites in Michigan previously amended with biosolids, collected over two years were shown to retain triclosan (0.55–3.5 nmol/kg) (Cha and Cupples oc = 9200 and stability to hydrolysis) in soil, thereby exposing soil dwelling animals such as earthworms to TCS toxicity and at the same time surreptitiously increasing the human body burden of TCS via trophic levels. In anaerobic digester, exposure to oft-high level TCS concentrations has been recorded as leading to the proliferation of TCS-resistant genes  to bioaccumulate in fatty tissues, there is no evidence in human tissues. There is evidence that TCS and its metabolites bioaccumulate in mice   was reduced when exposed to ≥0.52 μM TCS for 7 days  of 3.4 nM for 96 h exposure, TCS affected biomass of Anabaena flos-aquae the blue-green alga , resulted in epidermal tissue and nematocyst damage ; compare TCS   is a metabolite of TCS formed by bacterial methylation Bester , 2005. IThe negative impact of TCS on ecosystem is expected to have economic consequences. The United Nations Food and Agriculture Organization (FAO) reports FAO  that aboPlasmodium falciparum and Toxoplasma gondii  strains are all sensitive to TCS , confers high-level microbial resistance to TCS. It however remains to be elucidated the precise role of the sigma factors, in particular which of the factors, for example rpoS or rpoD is responsible for the mutation. Microbial resistance to TCS may lead to the worst scenario of the appearance of the antibiotic insensitive bacteria the so called super-bugs, as well as cross-resistance to other antibiotics such as isoniazid and ethionamide (an anti-tuberculosis pro-drugs), which target Mycobacterium tuberculosis enoyl acyl carrier protein reductase (InhA)  and cannot be used to directly address the effect of chronic exposures. Pursuant to this widely held criticism, additional data need be generated from in vitro and in vivo studies as well as carefully designed epidemiological studies in order to make a conclusive remark on the role of the chemical in health and disease.The detection of TCS in human fluids and tissues may not be an indicator of long term exposure as available data are insufficient to confirm its bio-accumulation in tissues (Geens et al. The precise role of TCS on the selection of antibiotic resistance genes as well as multidrug resistance genes in the environment needs be elucidated. The concentration of TCS that is required for resistance selection in environmental communities also needs be worked out. The relationship between TCS exposure and bio-accumulation in terrestrial animals is still inconclusive (Higgins et al.


The presence of peripheral circulating tumor cells indicates the possible existence of a tumor in vivo; however, low numbers of circulating tumor cells (CTCs) can be detected in peripheral blood of healthy individuals as well as patients with benign tumors. It is not known whether peripheral CTC counts differ between patients with benign colorectal disease and those with colorectal cancer.Comparative analysis of preoperative peripheral circulating tumor cells counts was completed in patients with benign colorectal disease  and non-metastatic cancer of the colon and rectum.P < 0.001). Colorectal cancer patients with tumors of the sigmoid colon displayed the highest CTC counts (4.87 ± 0.95/3.2 ml), followed by those with tumors of the rectum (3.73 ± 0.54/3.2 ml), ascending colon (3.5 ± 0.63/3.2 ml), transverse colon (2.4 ± 0.68/3.2 ml), and descending colon (2.08 ± 0.46/3.2 ml). Colorectal polyp patients with polyps in the rectum showed the highest CTC counts (2.2 ± 0.77/3.2 ml), followed by those with polyps in the ascending colon (1.82 ± 0.54/3.2 ml), sigmoid colon (1.38 ± 0.25/3.2 ml), transverse colon (0.75 ± 0.25/3.2 ml), and descending colon (0.33 ± 0.21/3.2 ml). The differences in CTC counts suggest that anatomical location of colorectal tumors may affect blood vessel metastasis. Meanwhile, patients with moderately differentiated and poorly differentiated tumors displayed higher peripheral blood CTC counts compared to those with well-differentiated tumors (P < 0.001). This result suggests that the type of tissue differentiation of colorectal tumors may act as another factor that affects blood vessel metastasis.The results of this analysis showed that patients with colorectal cancer had higher CTC counts than patients with colorectal polyps (3.47 ± 0.32/3.2 ml vs 1.49 ± 0.2/3.2 ml, Circulating tumor cells can be detected in the peripheral blood of colorectal cancer patients as well as patients with colorectal polyps. The differences in CTC counts suggest that anatomical location and the type of tissue differentiation of colorectal tumors may affect blood vessel metastasis. Colorectal cancer is the most common cancer in the world –3, and rThe presence of peripheral CTCs suggests that a tumor may be present in vivo, and preoperative detection of peripheral blood CTCs can be used to assess blood vessel metastasis of a tumor –9. When However, a low number of CTCs can be detected in the peripheral blood of some healthy individuals as well as patients with benign tumors , 11. TheA total of 61 patients  with colonic or rectal polyps, and 109 patients  with colonic or rectal carcinoma were studied at the department of surgery of Shanghai Tongren Hospital  between December 2014 and August 2016. After acquiring patient consent and ethics committee recognition, peripheral CTC detection was performed the day before operation. Patient data and pathological tumor characteristics are listed in Table Cytokeratin , Cytokeratin 7 (clone line OV-TL 12/30), and Cytokeratin 20 (clone line SD33) mouse anti-human cell keratin monoclonal primary antibodies, as well as carcinoembryonic antigen (clone line COL-1) mouse anti-human carcinoembryonic antigen monoclonal primary antibody, were obtained from Biocare Medical . Horseradish peroxidase-conjugated second antibody (goat anti-mouse) was obtained from Jackson Immuno Research Inc. . LCD45-AF594 fluorescent antibody was obtained from Santa Cruz Biotechnology . Nuclear staining (DAPI) antibody was obtained from Beyotime Biotechnology .CTCs were enriched by negative separation. Briefly, CD45 antibody beads were used to bind white blood cells, and CTCs were enriched in precipitation. This method enriches for all CTCs, including epithelial cell adhesion molecule (EpCAM) negative, cytokine (CK) negative, and epithelial-mesenchymal transition (EMT) condition CTCs . A total2O2 for 10 min at room temperature to eliminate endogenous peroxidase activity. Sections were washed with 1× PBS (5 min × 3), and then incubated with 10% fetal bovine serum for 30 min. Primary antibodies  were added and incubated at 4 °C for one night. Sections were washed with 1× PBS (5 min × 3), and HRP-labeled secondary antibodies  were added and incubated for 1 h. Sections were washed with 1× PBS (5 min × 3) and stained with diaminobenzidine for 15 min for color-developing. Sections were dyed with hematoxylin for 15 s, dehydrated in gradient alcohol at 15 min intervals, and incubated in xylene (30 min × 2). Sections were sealed with neutral resin and pictures were taken using a microscope.After surgeries and endoscopic resections, tumor tissues and polyp samples were immediately fixed in formalin for 24 hand paraffin embedded. Tissue sections were flattened on glass slides coated with poly-L-lysine. Sections were dewaxed in dimethyl benzene (30 min × 2), rehydrated in gradient alcohol , washed in 1× phosphate buffer saline (PBS) (5 min × 3), and then incubated in 3% Ht test. P < 0.05 was considered as a statistically significant result.Values are expressed as the mean ± standard error of the mean. Data were analyzed with Origin 8.0 software (OriginLab Corporation). Data recordings were evaluated by two-sample X2 = 0.023, P > 0.05), and the ages of the patients with polyps or carcinoma were not significantly different . A significant difference was observed in peripheral CTC counts between patients with colonic and rectal polyps and patients with colonic and rectal carcinoma .Characteristics of 61 patients with colonic or rectal polyps and 109 patients with colonic or rectal carcinoma were compared and analyzed , whereas tissue differentiation of colonic and rectal carcinoma was mainly classified as moderately differentiated adenocarcinoma (69.72%). For tissue pathology, tubulovillous adenoma was the most common pathology in patients with colonic and rectal polyps (62.3%), whereas papillary tubular adenocarcinoma was the most common pathology in patients with colonic and rectal carcinoma   and the descending colon , no significant difference was observed between the two types of tissue differentiation in patients with colorectal polyps  were the highest of all colorectal anatomical locations, moderate differentiation accounted for 73.91% (17/23), poor differentiation accounted for 17.39% (4/23), moderate and poor differentiation accounted for 91.3% (21/23), the combined percent of moderate and poor differentiation was the highest in all colorectal anatomical locations , no significant differences were observed across the tissue types , no significant differences were observed across the tissue types (P < 0.001).The importance of CTCs is becoming more apparent with recent advances in research –17. CurrP < 0.001) and descending colon (P < 0.05) compared to colorectal polyp patients with tumors in the same location. This may result from differences in anatomy and tissue differentiation throughout the colon and rectum. Additionally, the duration of fecal retention was prolonged in the sigmoid colon, ascending colon, and rectum compared to other parts of the colon, and this was especially noticeable in patients who suffered from chronic constipation. It is possible that the prolonged duration of fecal retention resulted in stimulation of the intestinal wall, which could contribute to colonic mucosal disease [Furthermore, CTC counts were noticeably different between patients with colorectal carcinoma and colorectal polyps with respect to anatomical location of the primary colorectal tumor. Specifically, CTC counts were significantly higher in colorectal carcinoma patients with tumors of the sigmoid colon ( disease –28. The P < 0.001) in CTC counts between patients with benign and malignant colorectal disease. When CTC counts were divided into two groups (> 1/3.2 and ≤ 1/3.2 ml), a significant difference was observed between colorectal polyps and carcinoma (P < 0.001). Specifically, higher CTC counts (> 1/3.2 ml) were observed in patients with colorectal carcinoma, whereas lower CTC counts (≤ 1/3.2 ml) were primarily observed in patients with colorectal polyps. However, when low numbers of CTCs are detectable, CTC counts cannot be used to indicate to the presence of benign or malignant colorectal disease due to the overlap in CTC counts between colorectal polyp patients and colorectal carcinoma patients. Based on the CTC counts in patients with different anatomical locations of colorectal polyps, CTC counts were highest in patients with rectal polyps (2.2 ± 0.77/3.2 ml). Therefore, the detection of peripheral CTCs could be used to indicate the presence of a malignant tumor in vivo, but only when counts are high (> 2.97/3.2 ml). Additionally, these findings confirm that peripheral CTCs can be detected not only in malignant tumors but also in benign disease, so if high peripheral CTCs detection value (> 2.97/3.2 ml) is used as a colorectal cancer screening criterion, some false positives will be eliminated as much as possible, and further research is required to determine the origin and significance of CTCs in patients with colorectal polyps.Previous studies have shown that low numbers of CTCs can be detected in the peripheral blood of some healthy individuals, as well as in patients with benign tumors , 11, sugP < 0.0001, [There are very few studies assessing the application of peripheral CTC counts for determining the presence of a primary tumor and its pathological characteristics , 29. One 0.0001, ). This sIn order to identify the factors that influence the number of peripheral CTCs, the degree of tissue differentiation in colorectal polyps and colorectal cancer was analyzed. Colorectal polyps were classified as high-grade intraepithelial neoplasia (HGIEN) or low-grade intraepithelial neoplasia (LGIEN), where the former is considered as a precancerous lesion. Colorectal cancers were classified as highly differentiated, moderately differentiated, or poorly differentiated. In patients with colorectal polyps, the average CTC count was 1.49/3.2 ml. When CTC counts were divided into groups of > 1/3.2 and ≤ 1/3.2 ml, the degree of tissue differentiation in patients with colorectal polyps had no effect on peripheral blood CTC counts. The average CTC count in patients with colorectal cancer was 3.47/3.2 ml. When CTC counts were divided into two groups of > 1/3.2 and ≤ 1/3.2 ml, patients with moderately differentiated and poorly differentiated tumors displayed higher peripheral blood CTC counts compared to those with well-differentiated tumors. These results suggest that a lower degree of tissue differentiation in colorectal cancer tumors corresponds to higher peripheral CTC counts.Tissue pathology in colorectal polyps and colorectal cancer was also analyzed as an additional factor that may influence peripheral CTC counts. Tissue pathologies of colorectal polyps were classified as serrated adenoma, tubular adenoma, tubulovillous adenoma, or proliferative polyps. Tissue pathologies of colorectal cancer were classified as papillary adenocarcinoma, tubular adenocarcinoma, papillary tubular adenocarcinoma, mucous adenocarcinoma, or signet-ring cell carcinoma. There was no difference between pathology types and CTC counts in colorectal polyps or colorectal carcinoma. Therefore, tissue pathology does not influence peripheral blood CTC count in colorectal disease.In summary, peripheral blood CTCs can be detected in patients with colorectal cancer as well as in patients with colorectal polyps. A significant difference in peripheral CTC counts was observed between benign and malignant disease; patients with colorectal cancer had significantly higher CTC counts than patients with colorectal polyps. High CTC counts (> 2.97/3.2 ml) correlated with the presence of a primary tumor. CTC counts varied with respect to location of the primary tumor, indicating that anatomical location and degree of tissue differentiation may affect peripheral CTC counts. Additional clinical studies with larger sample sizes are required to further validate these findings.


Hearing loss is the most common sensory impairment, but limited studies focused on the association of socioeconomic status (SES) with hearing loss among adults of working age. This paper aimed to fill this gap among Chinese adults. We obtained data from Ear and Hearing Disorder Survey conducted in four provinces of China in 2014–2015. The survey was based on WHO Ear and Hearing Disorders Survey Protocol and 25,860 adults aged 25 to 59 years were selected in this study. Trained local examiners performed pure tone audiometry to screen people with hearing loss, and those who were screened positively for hearing loss were referred to audiologists to make final diagnosis. SES was measured by occupation, education and income. Results show after adjusting for SES measures and covariates, in urban areas, compared with white-collar workers, blue-collar workers and the unemployed were more likely to have hearing loss, with an odds ratio of 1.2  and 1.2 , respectively. Compared with people with education of senior high school or above, those with junior high school, primary school and illiteracy had 1.6 , 2.1 and 2.6  times as likely to have hearing loss, respectively. In rural areas, the unemployed had 1.5  times the risk of hearing loss compared with white-collar workers, and illiterates had 1.6  times the risk of hearing loss compared with people with education of senior high school or above, after SES variables and covariates were taken into considerations. Income was not significantly associated with hearing loss in urban and rural areas. In conclusion, SES, in the form of occupation and education, was associated with hearing loss among working-aged population, and further studies are needed to explore the mechanism of such association. Hearing loss is the most common sensory impairment and has become a public health concern worldwide . HearingWorking-aged adults, defined as people aged 25–59 years in China, accounted for roughly 53% of the total population, 7. In aSocioeconomic status (SES), is associated with hearing loss–14, but In this study, using a cross-sectional, population-based Ear and Hearing Disorder Survey in four provinces of China, we aimed to examine the relationship between SES and hearing loss in Chinese adults aged 25 to 59 years. This study will fill the gap on this topic for China and contribute to world literature in the context of eastern countries.We obtained data from Ear and Hearing Disorder Survey, which was a population-based study conducted in four provinces of China  between August 2014 and September 2015. The survey design was established by a technical team based on WHO Ear and Hearing Disorder Survey Protocol , which hThe sampling frame covered almost 200 million people, representing about one in seven of the total population in China. Probability proportion to size (PPS) sampling method was used to identify 144 sites from 24 counties or districts in four provinces. Each site included 100 households which had lived in the registered address for over 6 months. A total of 47,511 individuals were randomly selected and 45,052 of them participated in the survey, yielding a participation rate of 94.8% [In this study, we restricted our analysis to 26,000 adults at the ages between 25 and 59 years, and after excluding 160 missing values, we obtained 25,840 individuals for analysis. Audiometry was performed by trained examiners according to the established protocols of Ear and Hearing Disorder Survey. Examiners were recruited from local primary health care institutions , and were trained by provisional technical teams in survey skills and audiological techniques. Before the household survey, examiners went to local sites to select audiometric test rooms with ambient noise levels not exceeding 40 dBA measured by sound level meters, and were equipped with MADSEN-Xeta pure tone audiometers and other required examination equipment. During the survey, noise-excluding headsets would be used if the ambient noise of testing rooms exceeded 40dB. Audiometric equipment was calibrated by a laboratory at the beginning and end if a study, and on a daily basis by team members using self-calibration against their known hearing levels. During and after the survey, a subsample with 5% of participants were rechecked and the consistence rates of rechecks both reached 90% and above [Examiners performed pure tone audiometry among people aged 25–59 years in a selected quiet room. Both ears were tested separately at 0.5, 1, 2, and 4 kHz to obtain the hearing threshold on each frequency point. There were no people who could not have both ears tested due to injury or ear infection in our survey. For those who could only have one ear tested, we performed audiometry in the better ear. Pure tone threshold averages in the better ear were calculated to identify grades of hearing loss according to the standard of WHO/PDH/97.3 , and theThis survey was ethically approved by China Disabled Persons' Federation (number: 2014&ZZ028). The committee board, which was composed of audiologists and epidemiologists, reviewed the study protocols and ethical situations. The authors had no access to identifying information for the study participants prior to data analysis. All participants signed the informed consent with interviewers to participate in the survey and clinical diagnosis. For those with severe hearing loss who were unable to sign the consent, family members represented them to sign the consent. We obtained data from this survey, which was performed independently from this specific study.The outcome variable was whether or not an adult had hearing loss. The independent variable was socioeconomic status, defined by three categorical variables: occupation , education  and income . White-collar workers in this study involved professional and governmental employees, and blue-collar workers referred to manual and services-oriented workers excluding farmers. CovariaLogistic regression models were used to evaluate multivariate associations between hearing loss and SES variables, and the odds ratios (ORs) with 95% confidence intervals (CIs) were presented. Although socioeconomic indicators are correlated, occupation, education and income are not interchangeable . TherefoIn this study, SES, as defined by occupation, education and income, was investigated regarding its association with hearing loss in working-aged adults in a population-based Earing and Hearing Disorder Survey in four provinces of China. According to the WHO Ear and Hearing Disorders Survey Protocol, individuals were first screened by local trained examiners using pure tone audiometry and were further referred to audiologists for final diagnosis of hearing loss. To the best of our knowledge, this is the first to investigate the association between SES and hearing loss in adults of working age from a population-based survey in China. We found that lower SES, in the form of occupation and education, was associated with higher risk of hearing loss in both urban and rural areas.Our findings showed that lower-class occupation was correlated with higher level of hearing loss, which is consistent with previous research. In thisThis study indicated that lower education was associated with elevated level of hearing loss when a wide range of covariates were taken into consideration, which is consistent with prior studies , 14. AltOur study found that income was not associated with hearing loss among working-aged adults in urban and rural areas. Lower income is usually linked with poor access to, utilization of, and quality of health care and then correlated with poorer health status . Such meThis study has several limitations. Since some factors that may affect response variability were not considered, we need to take caution to interpret our results. For instance, the main purpose of this study was to investigate the association between SES and hearing loss, but some risk factors, such as noise exposure, chronic diseases (i.e. hypertension and diabetes) and cigarette smoking, may contribute to the observed association . In addiDespite these limitations, the strengths of this study include a large-size, population-based design in four provinces of China based on the WHO Ear and Hearing Disorder Survey Protocol, access to a variety of socioeconomic measures and multiple covariates in the association of SES with hearing loss, as well as hearing conditions ascertained by audiologists according to the WHO criteria.This study investigated the association between SES and hearing loss among working-aged adults aged 25 to 59 years in four provinces of China. We found that SES, in the form of occupation and education, was associated with hearing loss. However, income was shown not to be associated with hearing loss in our findings. This study contributes to the literature on hearing loss in developing nations of a non-Western context. Further studies are warranted to confirm our findings and to better understand how SES is related to hearing loss, which will help identify how to prevent hearing loss and to provide more specific suggestions to improve hearing status for working-aged population.


Resected bowel showed one perforation and several areas of impending perforations. Characteristic broad, pauci-septate hyaline, empty looking hyphae with infrequent branching were found transmurally and showing angio-invasion. Local intestinal tissue trauma coupled with her sub-normal immune status permitted this unusual nosocomial infection. Histopathological demonstration of the fungus in surgical specimens remains cornerstone of diagnosis of mucormycosis in view of its non-specific symptoms, low isolation rates of mycological culture and lack of other rapid tests. Mucormycosis is a rare but highly invasive opportunistic fungal infection. Gastrointestinal disease although uncommon is highly fatal. We report a case of jejunal mucormycosis in a 24 year old undernourished female with preceding surgical intervention for acute intestinal obstruction of tubercular etiology. On 8 Mucormycosis is a rare but highly invasive opportunistic infection of ubiquitous fungi of order Mucorales. It is the third most common nosocomial fungal infection following candidiasis and aspergillosis . Hyphal  Most common presentation of mucormycosis is rhinocerebral 39-48%) followed by pulmonary (17-24%) and cutaneous (19%). Gastrointestinal (GI) mucormycosis accounts for 7-13% of cases . Its clinical presentation is non-specific and preoperative diagnosis is difficult. GI mucormycosis has very high mortality as 85-90% die (8% follow3). Serology for HIV and hepatitis B surface antigen had negative results. The patient underwent exploratory laparotomy for suspected perforation peritonitis. Peritoneal cavity contained approximately two litres of biliopurulent fluid. The affected ileal segment was resected and ileo-ileal anastomosis was performed. The resected small bowel segment (15 cm) showed one stricture with luminal narrowing and three perforations  woman presented with symptoms of acute bowel obstruction. She complained of fever, multiple episodes of vomiting, abdominal pain, distention and non-passage of stools for three days. Her blood pressure was low (78/44 mm Hg), had tachycardia (114/minute) and tachypnea (24/minute). Clinical examination demonstrated signs of peritonism with distended abdomen, and tenderness and guarding in examination. Erect X-ray abdomen revealed free gas under the diaphragm. Routine hematologic and biochemical parameters were within normal limits except for leukocytosis  requiring constant ionotropic support and tachycardia (92-104/minute) was evident postoperatively. On eighth postoperative day she developed bilious oozing from the suture line and bilio-purulent fluid from the drain tube prompting clinical diagnosis of postoperative peritonitis. Bedside ultrasound revealed dilated bowel loops and free peritoneal fluid with internal echoes suggestive of peritonitis. The re-look exploratory laparotomy showed anastomotic site leak and one litre biliopurulent fluid in peritoneal cavity. Bowel resection with jejunostomy was performed and ileal mucus fistula made. Resected segment of jejunum was edematous, bile-stained, exudate covered, had one perforation  and seveRhizopus species has been found to be the most frequent culture isolate (34-47%) followed by Mucor (18-19%)  with diastase and silver stains are useful for highlighting organism morphology and demonstration of vascular invasion. Due to its rarity, mucormycosis is seldom suspected preoperatively and mycologic cultures often unavailable. Although useful for species identification and drug susceptibility tests, culture cannot differentiate invasive infection and innocuous contamination, unless isolated repeatedly from sterile body sites . CultureGI mucormycosis is often lethal and 85% to 90% of patients die , 3. BoweWe here shared our experience of an uncommon case of nosocomial jejunal mucormycosis presenting as anastomotic site leak and perforation peritonitis in a patient with malnutrition and antecedent tubercular ileitis. Mucormycosis should be considered as a possible etiology of anastomotic site leak in patients with sub-optimum immune status like those with malnourishment. Endoscopy  is a less invasive technique for early diagnosis. Prompt surgical debridement and anti-fungal treatment lower mortality rate. Failure to show expected recovery or sudden clinical deterioration, protracted and unexplained hypotension, as happened in our case are pointers to unresolved issues.


The occurrence of tinnitus can be linked to hearing loss in the majority of cases, but there is nevertheless a large degree of unexplained heterogeneity in the relation between hearing loss and tinnitus. Part of the problem might be that hearing loss is usually quantified in terms of increased hearing thresholds, which only provides limited information about the underlying cochlear damage. Moreover, noise exposure that does not cause hearing threshold loss can still lead to “hidden hearing loss” (HHL), i.e., functional deafferentation of auditory nerve fibers (ANFs) through loss of synaptic ribbons in inner hair cells. While it is known that increased hearing thresholds can trigger increases in spontaneous neural activity in the central auditory system, i.e., a putative neural correlate of tinnitus, the central effects of HHL have not yet been investigated. Here, we exposed mice to octave-band noise at 100 and 105 dB SPL to generate HHL and permanent increases of hearing thresholds, respectively. Deafferentation of ANFs was confirmed through measurement of auditory brainstem responses and cochlear immunohistochemistry. Acute extracellular recordings from the auditory midbrain (inferior colliculus) demonstrated increases in spontaneous neuronal activity  in both groups. Surprisingly, the increase in spontaneous activity was most pronounced in the mice with HHL, suggesting that the relation between hearing loss and neuronal hyperactivity might be more complex than currently understood. Our computational model indicated that these differences in neuronal hyperactivity could arise from different degrees of deafferentation of low-threshold ANFs in the two exposure groups. Our results demonstrate that HHL is sufficient to induce changes in central auditory processing, and they also indicate a non-monotonic relationship between cochlear damage and neuronal hyperactivity, suggesting an explanation for why tinnitus might occur without obvious hearing loss and conversely why hearing loss does not always lead to tinnitus. Epidemiological data suggest a close relation between hearing loss and tinnitus. For example, most tinnitus patients also have a certain degree of hearing loss , 2, tinnClinically, hearing loss is quantified through pure-tone audiometry, which measures thresholds for detecting tones in quiet. However, hearing thresholds alone only convey a limited picture of actual cochlear damage. The degree of outer hair cell loss, for example, only shows a moderate correlation to hearing threshold shifts , and cocThus, hearing thresholds do not provide a complete picture of hearing function. Indeed, recent evidence even suggests a considerable degree of “hidden hearing loss” (HHL) might be present despite a normal audiogram. Investigations in mice have shown that noise exposures producing only a temporary elevation of hearing thresholds can lead to loss of synaptic ribbons at synapses between IHCs and auditory nerve fibers (ANFs), permanently reducing the amplitude of wave I of the auditory brainstem response (ABR) . ANFs wiPeripheral hearing loss can lead to pronounced changes in the central auditory system, with reduced inhibitory neurotransmission –27, incrHere, we investigate how noise-induced HHL affects spontaneous and evoked neuronal activity in the auditory midbrain of mice. In contrast to most previous studies employing unilateral noise exposure, we employed bilateral noise exposure – more typical of the noise exposure generally encountered by human listeners. After exposing two groups of mice to different levels of noise , we compared the effects of “hidden” and “obvious” hearing loss on IC responses. Although spontaneous firing rates increased in both exposure groups, the increase was greatest in the animals exposed to the lower (100 dB SPL) sound level, which showed ANF deafferentation without permanent shifts in hearing thresholds. Using a computational model, we demonstrate that this non-monotonic relationship between the degree of cochlear damage and the degree of spontaneous neuronal hyperactivity is explicable in terms of different degrees of deafferentation of high- and low-threshold ANFs, suggesting that specific ANF deafferentation patterns could differ significantly in their effect on auditory function. Our results thus indicate that differences in the specific patterns of cochlear damage, which cannot be reliably determinated from hearing threshold measurements alone, might account for some of the heterogeneity observed in the relation between hearing loss and tinnitus.Subjects were 23 male CBA/Ca mice. Mice were 7–19 weeks old at the time of noise exposure. Control animals were age-matched littermates. ABRs were recorded 1–14 days prior to, 1 day after, and 4 weeks after noise exposure. IC recordings took place 4 weeks after noise exposure. At the end of the final experiment, mice were overdosed with an intra-peritoneal (i.p.) injection of sodium pentobarbital. All experiments were performed in accordance with the United Kingdom Animal (Scientific Procedures) Act of 1986.Mice were anesthetized with ketamine and medetomidine (i.p.) and positioned in a custom-made sound-proof booth on a heated pad directly underneath the center of a speaker (Stage Line PA Horn Tweeter MHD-220N/RD) positioned 45 cm above. The speaker was calibrated prior to each use to ensure that the frequency response was flat (±2 dB) over the 8–16 kHz range. Noise exposure was performed with an octave-band noise (8–16 kHz) at 100 or 105 dB SPL for 2 h. Noise stimuli were generated using an RX6 processor , attenuated as required (TDT PA5) and amplified (TDT SA2). During the noise exposure, pedal reflex and breathing rate were checked every 30 min. Control animals were not exposed to any additional sound beyond the normal background noise in the animal unit.For ABR recordings, animals were anesthetized with an i.p. injection of ketamine and medetomidine. ABR recordings were obtained using subdermal needle electrodes , one inserted at the vertex, and one each behind the ipsilateral and contralateral pinnae. Electrode signals were low-pass filtered  and recorded at 24 kHz sampling rate . For analysis, ABR data were filtered using a bandpass filter . Stimuli were either tone pips  or clicks , both delivered at a rate of 20/s. Stimuli were generated using a TDT RX6 processor, attenuated as needed (TDT PA5), amplified (TDT SA2), and presented in free-field condition with the speaker (TDT FF1) positioned at a 45° to the animal’s axis at a distance of approximately 15 cm. The ear contralateral to the speaker was blocked using a foam earplug. Before the start of each experiment, the transfer function of the speaker was measured with a microphone  placed at the location of the animal’s ear with the animal in place. This function was used to calibrate individual tones so that the overall output of the speaker was flat across frequency to ±3 dB. ABR thresholds were determined visually by estimating the lowest sound level at which deflections in the ABR waveform were judged to be greater than the background variability in the waveforms. Measurements of wave amplitudes were performed using custom Matlab software: a time window containing the wave of interest was selected by the user, and the software then detected maxima and minima of the ABR traces within that window. ABR wave amplitudes were measured from the peak to the following trough.Animals were anesthetized with an i.p. injection of ketamine and medetomidine, followed by administration of dexamethasone and atropine sulfate. Lactated Ringers solution was given every 2 h to maintain hydration. The animal’s temperature was maintained at 37.5°C using a homeothermic blanket connected to a rectal thermistor. Breathing rate was monitored throughout the surgery, and then at 45-min intervals throughout the recording. Once the pedal reflex had been abolished, the mouse was placed in a nose clamp to stabilize the head while leaving the ears free. To access the IC, a large craniotomy  was performed on the right-hand side, revealing the full surface of the right IC. Extracellular, multi-unit recordings were made using single-shank silicon multi-electrodes with 16 recording sites . This arrangement of electrode sites enabled sampling across the full extent of the central nucleus of the IC. The probe was advanced manually until the tip just touched the collicular surface. Using a remote hydraulic microdrive , the electrode array was then advanced rapidly by 2000 μm, to minimize the duration of tissue compression during the initial penetration, and then retracted by 500 μm. Electrode signals were recorded at 24 kHz sampling rate and bandpass-filtered between 300 and 9000 Hz (TDT RX5).To record frequency-response areas (FRAs), tone pips were played in sequential order from 4 to 70 kHz in one-eighth octave steps, with sound level ranging from 0 to 80 dB SPL in 5 dB steps. Tone pip duration was 100 ms, with a rise/fall time of 5 ms, and the inter-stimulus-interval was 400 ms. The speaker was positioned at a 45° to the animal’s axis and at a distance of approximately 15 cm from the animal’s left ear. The right ear was plugged with a sound-attenuating plug. The equipment for sound generation and delivery was the same as for the ABR measurements. The FRA measurement was repeated three times.To obtain a measure of the spontaneous firing rates, we recorded 100 epochs of 500 ms duration without sound presentation. The speaker was unplugged during the recording of spontaneous activity.To obtain multiunit activity, the electrode signals were first stripped of the local field potential by applying an additional high-pass filter with cut-off at 600 Hz, and action potentials were then classified using a latent variable spike-sorting algorithm  to separin situ identifications, multiphoton imaging was used in an upright LSM 510 confocal microscope (Zeiss). Ribbons were identified from z-projections and only those with both labels positively identified and were manually counted. Ribbons per cell were typically determined as averages from the groups of 8–12 IHCs from the 10–30 kHz region of the cochleae. No account was taken individual variations in the cochlear frequency place map between animals. The differences between the resulting data and reported figures from decalcified and dissected tissue  may refWe have set up a computational model of the early auditory system, as described below, to study the effects of different patterns of ANF deafferentation on spontaneous activity in the central auditory system. The model is based on previous models of the effects of loss of inner and outer hair cells and damage to hair cell stereocilia , 47 as wf*(I) is then+ denotes positive rectification, 0 ≤ hd < 1 represents the fraction of missing high-threshold fibers, and hf = 100 spikes/s is the firing rate where deafferentation starts to influence the AN population response. In addition to selective deafferentation of high-threshold ANFs, we also consider cases where all fiber types get deafferented:Auditory nerve responses are modeled with a rate-level function that represents the average response of a small population of ANFs, comprising low-, medium-, and high-threshold fibers, with similar CFs . The effad scales the whole AN population rate-level function, and thus (for hd = 1) models equal deafferentation of all fiber types when it is set to a value between 0 and 1. When both hd and ad are set to values < 1, deafferentation with a bias toward high-threshold fibers is created. Examples of the resulting AN population rate-level functions are shown in Figure The parameter wg and ng), a variety of different response types can be generated , as thisee Ref. , for mor nucleus , 48, 49.h :In the model, we assume that the mean firing rate of the PNs is stabilized at a certain target level  through homeostatic plasticity, which scales the strength of excitatory and inhibitory synapses onto the PN in opposite directions. When the mean activity of the PN is permanently below the target, homeostatic plasticity increases excitation and decreases inhibition to bring activity back up to the target level. Prolonged increases in activity lead to changes in the opposite direction. Synaptic scaling is implemented through the homeostasis factor h required to reach the desired target mean activity for a certain pattern of cochlear damage is determined numerically.The exact value of t tests were used unless otherwise stated.All data analysis as well as implementation and evaluation of the model were done using MATLAB . To test for significant differences, n = 6 animals) or 105 dB SPL  for 2 h, while the animals were anesthetized. The control group consisted of eight age-matched mice.We investigated the effects of two different levels of noise exposure – 100 dB SPL and 105 dB SPL – on young adult male CBA/Ca mice, using ABR measurements, cochlear immunohistochemistry, and multiunit recordings from the IC. Noise exposure was performed with an octave-band noise (8–16 kHz) at 100 dB SPL . In the 105-dB-SPL group, thresholds remained significantly elevated by around 20–25 dB at 11 and 16 kHz (p < 0.01 at both frequencies), but recovered, and were no longer significantly different from pre-exposure levels, at 32 and 48 kHz . The strongest reduction in ABR amplitude, in conjunction with an increase of the response threshold, was observed in the group exposed to 105-dB-SPL noise , the 100-dB-SPL (n = 3) and the 105-dB-SPL (n = 4) groups, and loss of synaptic ribbons was quantified using immunohistochemistry .To confirm that the observed reduction of ABR wave I amplitude was related to deafferentation of AN fibers, cochleae were extracted from representative animals from the control  of (anesthetized) noise-exposed and control mice using 16-channel single-shank electrode arrays see . A totalp < 0.01, Figure In control animals, CF-tone evoked thresholds of ICc recordings ranged from 0 to 45 dB SPL, with a mean of 15.7 ± 1.3 dB SPL. The range of thresholds recorded from the ICc of noise-exposed mice was similar (0–60 dB SPL for 100-dB-SPL exposure and 0–65 dB SPL for 105-dB-SPL exposure); however, the mean threshold of 31.6 ± 1.4 dB SPL in the 105 dB SPL group was significantly higher than in the control group (p < 0.01 in both cases). The average spontaneous firing rate was 26.3 ± 4.2 spikes/s in the 100-dB-SPL exposure group and 11.7 ± 3.1 spikes/s in the 105-dB-SPL exposure group. The difference in spontaneous firing rate between the two noise exposure groups was also significant (p < 0.01). To test for significant differences in spontaneous firing rates in different frequency regions, recordings were grouped according to their CFs . For CFs <8 kHz and >32 kHz, there were too few recordings in the control data to allow for meaningful statistical analysis. In the control group, average spontaneous rates were around 6–8 spikes/s across frequencies. Spontaneous firing rates in the 100-dB-SPL group were significantly increased in recordings with CFs from 8 to 12 kHz, 12 to 16 kHz, and 16 to 24 kHz . In the 105-dB-SPL group, a significant increase in spontaneous firing rates was seen in the 12–16 kHz range (p < 0.01). Spontaneous firing rates were also higher than in control mice in the 8–12, 16–24, and 24–32 kHz frequency ranges, but the increases did not achieve significance.Spontaneous firing rates were generally low in the control animals at 7.0 ± 1.3 spikes/s. In both exposure groups, the average spontaneous firing rates were significantly increased compared to control animals  leads to neuronal hyperactivity in the central auditory system, deafferentation of low-threshold fibers (with high spontaneous activity) could even reduce spontaneous firing rates . MoreoveIn the model, we first created different patterns of ANF deafferentation, ranging from selective deafferentation of high-threshold ANFs to a pattern where all fiber types are affected to a similar degree see B. By thihypo-activity with spontaneous firing rates lower than before cochlear damage . Finally, in the model, additional increases of peripheral thresholds always increase spontaneous firing rates in the central auditory system. Therefore, the model demonstrates that the same degree of elevation of spontaneous firing rates can be generated by different types of cochlear damage, and that trajectories exist through the “cochlear damage space” where more damage can even lead to a reduction in spontaneous firing rates in the central auditory nervous system, despite the presence of homeostatic plasticity mechanisms.Figure n = 15 ears) and control participants . Despite the significant difference in average amplitude, there is a considerable overlap in the distributions. Figure The ABR results from the 100-dB exposed mice with HHL resembled our findings from an earlier study in which we compared human tinnitus subjects with clinically normal hearing thresholds to age-, gender-, and hearing-matched control subjects, showing that the tinnitus group had significantly smaller amplitudes of ABR wave I . A direcWe examined peripheral and central auditory function in mice exposed to different levels of noise; 100 dB SPL to elicit temporary shifts in hearing thresholds but long-term deafferentation of IHC synapses, and 105 dB SPL to elicit both permanent threshold shifts and deafferentation. A striking finding is the non-monotonic relationship between the severity of cochlear damage and the degree to which spontaneous firing rates in the ICc were elevated, with less damage leading to more hyperactivity Figures B,C. FromOur noise exposure paradigm for HHL was modeled on that of Kujawa and Liberman , who expWe observed significant increases in ICc spontaneous firing rates in both exposure groups. Data from the animals exposed to 100-dB-SPL noise suggest that HHL can lead to the development of increased spontaneous firing rates, an outcome we previously predicted from a computational model designed to account for the effects of deafferentation of high-threshold ANFs . In miceIn the animals exposed to noise at 105 dB SPL, we observed the strongest increase in spontaneous firing rates at around 12–16 kHz, where hearing thresholds were permanently increased, matching recent reports from guinea pigs  and hamsAn important difference between the two exposure group in our study could be the degree of damage to outer hair cells. In the 105 dB SPL group, which suffered a permanent threshold increase due to the noise exposure, permanent damage to or even loss of outer hair cells might have occurred . In the Several recent studies , 57, 66 Our data do not enable us to determine whether the increase in spontaneous activity in the ICc is generated locally, or inherited from another processing stage in the auditory pathway. It has recently been demonstrated that ablation of the contralateral DCN abolishes noise-induced hyperactivity in the IC , suggestAn open question is whether the mice in our study were experiencing tinnitus – we did not perform behavioral tests. Several recent studies have reported behavioral evidence of tinnitus in mice , 66, 75,Could the increased spontaneous firing rates we observed in the IC of noise-exposed mice represent a neural correlate of tinnitus? The relationship between exposure frequency range and the location of increases in spontaneous activity on the tonotopic axis of the IC in our study is similar to the relation between exposure frequency range and the putative tinnitus pitch in gerbils . MoreoveOne important difference between our study and most other studies on animal models of tinnitus is that we employed bilateral, rather than unilateral, noise exposure. Although unilateral noise exposure has the advantage of preserving hearing in one ear, which can then serve as a within-subject control , noise exposure bilaterally is more representative of the case in human listeners, where usually both ears are exposed to noise (with rifle shooting being possibly the most prominent exception). It remains to be determined whether bilateral noise exposure is more or less likely to lead to tinnitus in animals. We have recently demonstrated that unilateral earplugging can lead to the perception of phantom sounds in normal-hearing human volunteers , which iAn important insight from our electrophysiological and modeling results is that they offer an indication of why hearing loss might not always lead to tinnitus. If the relationship between cochlear damage and the strength of a putative neuronal correlate for tinnitus is indeed non-monotonic, then some specific patterns or configurations of cochlear damage might be more likely to lead to tinnitus than others. This finding could offer an interesting new approach toward understanding the pathophysiology of tinnitus and tinnitus heterogeneity, and for evaluating potential tinnitus triggers.The human data presented in this manuscript is from a previous study , which hLH designed research, performed experiments, analysed data, and wrote the manuscript. WB performed experiments and wrote the manuscript. LA performed experiments. H-CO performed experiments and analysed data. JA supervised experiments, analysed data, and wrote the manuscript. DM designed research, supervised experiments, and wrote the manuscript. JL designed research, supervised experiments, and wrote the manuscript. RS designed research, analysed data, produced all figures, and wrote the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Many drugs used for cancer chemotherapy produce reactive oxygen species, thus leading to various complications including nephrotoxicity, cardiotoxicity, and ototoxicity. We have provided a haplogroup analysis of a cohort of cancer patients treated with chemotherapy and compared factors associated with associated hearing loss. This observational cohort study includes a pure-tone audiometry of the patients who underwent chemotherapeutic treatment. Medical history, presence of risk factors for hearing loss, toxic habits, and association with haplogroups have been determined. 40% of patients developed hearing loss after administration of cisplatin, which was bilateral and symmetrical and of high frequencies. The most frequent haplogroup was H with a slight overexpression of groups V and K and a low frequency of groups J and T. No association of the haplogroup types with the hearing loss has been found; however age was revealed as an important determining factor. Ototoxicity caused by cisplatin is manifested as bilateral, symmetrical, and predominantly high frequency hearing loss. Although we did not find a strong correlation of haplogroups with ototoxicity, our results revealed the existence of a risk group of elderly patients over 60, which are more susceptible to hearing loss induced by cisplatin, than young adults, regardless of preexisting hearing loss. Human mitochondrial DNA (mtDNA) haplogroups (subclades) are defined as genealogical groups of mitochondrial variants sharing a common maternal ancestor . It has Although mitochondria are both the main source and the main target of ROS, environmental ROS may be equally deleterious also by contributing to mtDNA/nDNA damage in a vicious circle. In particular, ROS deriving from the action of DNA cross-linking agents, such as cisplatin, represent a great obstacle towards cancer chemotherapy due to their side-effects which include cardiotoxicity, nephrotoxicity, and ototoxicity –10. DrugIt is still unclear what might be the risk factor(s) enabling predicting the ototoxicity. The toxicity of cisplatin has been shown to be dependent on genetic variations related to individual mutations or polymorphisms of mitochondrial enzymes that play a pivotal role in hearing loss. Polymorphisms of the glutathione S-transferase (GST) gene family members have been linked to cisplatin-mediated individual ototoxicity . AminoglThis is a descriptive, observational cohort study involving adult cancer patients (>18 y.o.) of Spanish Caucasian origin. A group of patients who were treated with a course of anticancer therapy between January 2009 and January 2015 in the oncology department at the Vall d'Hebron Hospital in Barcelona were included in the study. A total of 72 individuals who received cisplatin were selected for this study. Those who required combination chemotherapy or had already started the treatment or had an otological disease as well as those who required a concomitant antineoplastic treatment were excluded from the study.A pure-tone audiometry was performed before treatment initiation and at the end of the 3d dose treatment. For the calculation of hearing loss, the following frequencies were used: 125, 250, 500, 1000, 2000, 4000, and 8000 Hz. The airway was taken as a reference point for calculating the hearing loss as long as there was no more than 5 dB gap between airway and bone conductivity. The average decibel values of these frequencies taken by airway of pre- and posttreatment visit were obtained. Subsequently, both averages are subtracted. Hearing loss greater than 10 dB was counted as significant hearing loss.The samples were haplogrouped by PCR amplification of short mtDNA fragments, followed by restriction enzyme analysis obtained from buccal mucosa, as described elsewhere . The firWe have performed an observational cohort study among patients treated with cisplatin . The samAudiometric studies revealed that 40% of all patients who underwent chemotherapeutic treatment with cisplatin have developed hearing loss with an average loss of approximately 14.5 dB. The hearing loss was bilateral and symmetrical and of high frequencies. The percentage of individuals with hearing loss increased to 54% only if frequencies 4000 and 8000 Hz are taken into account. In this case, the average loss increases to 24.6 dB .In order to correlate cisplatin-mediated hearing loss with possible variations in mtDNA we performed analyses of haplogroups. Haplogroup H was the most common one among cancer patients (48.6%), followed by K (15.3%), V (12.5%), U (8.3%), WIX (5.6%), J (4.1%), JT (2.8%), A, and T groups with 1.4% . AlthougProspective monitoring for ototoxicity allows for comparison of auditory outcomes across clinical trials, as well as for early detection, potential alterations in therapy, and auditory intervention and rehabilitation to ameliorate the adverse consequences of hearing loss . CisplatThe most frequent haplogroup obtained in our study was H (48%), coinciding with the percentage of occurrence of haplogroups in Spain and Europe. This is not surprising as HV and branch haplogroups occur predominantly in Spain and Europe. However, we obtained a lower frequency for the haplogroups J and T as compared to Spanish and European media and an overexpression of haplogroups V and K. This difference seems to be attributed to a small sample size of already preselected (cancer) patients, as well as to a nonhomogeneous population that likely includes non-Spanish origin patients in the Barcelona area. Despite significant variability in the development of cisplatin ototoxicity, it is impossible to use it as a risk factor for cisplatin-induced hearing loss. However, it has been shown that the genetic characteristics of individuals, including point mutations of both nDNA and mtDNA, may affect response to certain drugs. Genetic predisposition to cisplatin-induced hearing loss can also be related to mitochondrial polymorphisms of the enzymes encoding antioxidative proteins. Furthermore, it has been observed that some patients with cisplatin ototoxicity are from the rare European mitochondrial haplogroup J, which has been associated with Leber's hereditary optic atrophy. Similarly, patients with testicular cancer undergoing cisplatin treatment showed differences in polymorphisms functional for glutathione S-transferase (GST) enzyme which is responsible for the phase II of drug metabolism.Overall, provided a high enough sample size and proper controls, a study similar to ours may determine the predictors which should be taken into account when providing anticancer therapy. Eventually, combined screening for haplogroups and audiometric analyses may become part of the personalized medicine to define a risk group of patients for which a strategy other than chemotherapeutic treatment strategy should be applied.


Hearing impairment is suggested to be associated with depression in the elderly. The present study evaluated the risk of depression after hearing impairment in all age groups matched by age, sex, income, and region of residence.The Korean Health Insurance Review and Assessment Service—National Patient Samples were collected for a period from 2002 to 2013. Hearing impairment was defined as a hearing threshold ≥ 60 dB in both ears or as ≥ 80 dB in one ear and ≥ 40 dB in one ear. Hearing-impaired participants performed a pure tone audiometry test 3 times and an auditory brainstem response threshold test once. The 6,136 hearing-impaired participants were matched 1:4 with 24,544 controls with no reported hearing impairment for age, sex, income, and region of residence. Depression was investigated based on the International Classification of Disease-10 codes F31 (bipolar affective disorder) through F39 (unspecified mood disorder) by a psychiatrist from 2002 through 2013. The crude (simple) and adjusted  hazard ratio (HR) of hearing impairment on depression were analyzed using Cox-proportional hazard model.The rate of depression was significantly higher in the severe hearing-impaired group than in the control group . Severe hearing impairment increased the risk of depression . In a subgroup analysis, young (0–29 years old), middle-aged (30–59 years old), and old (≥ 60 years old) severe hearing-impaired groups showed significantly increased risk of depression compared to controls with no reported hearing impairment. In accordance with income level, severe hearing impairment elevated depression in the low and high income groups, but not in the middle income group.Severe hearing impairment increased the risk of depression independently of age, sex, region, past medical histories, and income (in low and high income persons but not in middle income persons). Hearing impairment is one of the most common disorders, with prevalences of 22.73% and 21.7% in the general Korean and US populations, respectively ,5. Both The relationship between hearing impairment and depression is thought to be bidirectional. Hearing impairment has been suggested to be related to impaired social communication and cognitive function, thereby resulting in social isolation in the elderly ,8,9. TheAlthough previous studies reported the adverse effects of hearing impairment on depression, most of these studies were cross-sectional studies that could not delineate the causal relationship between hearing impairment and depression ,4,5. A fThe ethics committee of Hallym University (2014-I148) approved the use of these data. Written informed consent was exempted by the Institutional Review Board.This national cohort study relied on data from the Korean Health Insurance Review and Assessment Service—National Patient Sample (HIRA-NPS). The Korean National Health Insurance Service (NHIS) selects samples directly from the entire population database to prevent non-sampling errors. Approximately 2% of the samples (one million) were selected from the entire Korean population (50 million). These selected data can be classified at 1,476 levels  using randomized stratified systematic sampling methods via proportional allocation to represent the entire population. After data selection, the appropriateness of the sample was verified by previous study . The detBecause all Korean citizens are recognized by a 13-digit resident registration number from birth to death, exact population statistics can be determined using this database. It is mandatory for all Koreans to enroll in the NHIS. All Korean hospitals and clinics use the 13-digit resident registration number to register individual patients in the medical insurance system. Therefore, the risk of overlapping medical records is minimal, even if a patient moves from one place to another. Moreover, all medical treatments in Korea can be tracked, without exception, using the HIRA system. In Korea, the notice of a death to an administrative entity is legally required before a funeral can be held.Out of 1,025,340 cases with 114,369,638 medical claim codes, we included participants who were registered as a hearing-impaired person in the Ministry of Health and Welfare. Hearing impairment was defined as having a hearing threshold ≥ 60 dB in both ears or ≥ 80 dB in one ear and ≥ 40 dB in the other. In Korea, to be registered as a hearing-impaired person, one must be checked three times by a pure tone audiometry test (PTA) and once by an auditory brainstem response. The average hearing threshold of PTA was calculated as follows: (500 Hz + 2*1000 Hz +2* 2000 Hz + 4000 Hz)/6.The hearing-impaired participants were matched 1:4 with the participants among this cohort who were never diagnosed as having a hearing impairment or other disabilities (control group) from 2002 through 2013. The matches were processed by age, group, sex, income group, and region of residence. To prevent selection bias when selecting matched participants, the control group participants were sorted using a random number order and were then selected from top to bottom. It was assumed that the matched control participants were involved at the same time of the matched hearing-impaired participants. Therefore, the control group participant who died before the involvement time of the matched hearing-impaired participant was excluded. The participants who had a history of depression before hearing impairment were excluded in this study (n = 294). The hearing-impaired participants for whom we could not identify enough matching participants were excluded (n = 95).Finally, 1:4 matching resulted in the inclusion of 6,136 of hearing impaired participants and 24,544 control participants . HoweverThe age groups were classified using 5-year intervals: 0–4, 5–9, 10–15…, and 85+ years old. A total of 18 age groups were designated. The income groups were initially divided into 41 classes . These groups were re-categorized into 11 classes (class 1 [lowest income]—11 [highest income]). The region of residence was divided into 16 areas according to the administrative district. These regions were regrouped into urban  and rural  areas.The past medical histories of participants were evaluated using ICD-10 codes. For the accuracy of diagnosis, dementia (F00 and G30), hypertension (I10 and I15), diabetes (E10-E49), and dyslipidemia (E78) were checked if the participants were treated ≥ 2 times.Depression was defined using the ICD-10 codes F31 (bipolar affective disorder) through F39 (unspecified mood disorder) by a psychiatrist from 2002 through 2013.To analyze the hazard ratio of hearing impairment on depression, Cox-proportional hazard model was used. In this analysis, crude (simple) and adjusted  model was used. 95% confidence interval (CI) were calculated.For the subgroup analysis, we divided the participants with age and sex . In another subgroup analysis, we grouped participants according to income level  . HoweverIn the present study, severe hearing impairment significantly elevated depression in the low and high income groups, but not in the middle income group. Because the high income group might be more privileged for leisure activity and social activities, which needs auditory function, the adverse effects of hearing impairment could be magnified in the high income group. On the other hands, hearing impairment was suggested to be related to low educational level, unemployment, and economic hardship . These aThe present study extended past studies on the influence of hearing impairment on depression with several strengths. Foremost, this study is one of the largest nationwide population studies encompassing entire age groups. The data were based on a database that covers the entire population and were verified by a statistician. Moreover, by matching age, sex, income, and region of residence, confounding effects of these general characteristics on hearing impairment and depression were excluded. Matching income and region was crucial because these factors decide the availability of medical care. Using the Korean NHIS, income level, which determines the allocation of medical welfare, was precisely surveyed. In addition, subgroup analyses were conducted to estimate specific associations of each confounder. Hearing impairment was based on the thresholds of pure tone audiometry. The participants who had a history of depression before hearing impairment were excluded in this study, and depression was investigated using the medical records within HIRA. Thus, recall bias could be prevented in the present study. HIRA data encompass all citizens of the nation, without exception. Therefore, there were no missing participants, and the confounding effect of pre-existing depression before hearing impairment could be minimized.The diagnosis of hearing impairment or depression could be delayed in some populations. In addition, audiometric hearing evaluation was not conducted in control group. However, the likelihood of a delayed or missed diagnosis of hearing impairment might be small because the diagnosed hearing-impaired person has considerable benefits in Korea, including health insurance. Another weak point of the present study is that only the moderately severe (≥ 60 dB) and more severe degrees of hearing impairment were counted in the present study. The severity of depression also was not discriminately considered in this study. Because whole age groups were included in this study, depression in young participants was also mixed in the present results. However, there were only 7 subjects with depression less than 10 years old, which might have no significant impact on the present results. Lastly, hearing rehabilitation using a hearing aid or cochlear implant could compensate for the effects of hearing impairment ,23. HoweSevere hearing impairment increased the risk of depression in the overall population in Korea. Severe hearing impairment was a risk factor for depression in the young, as well as in the older population. The significant effect of severe hearing impairment on the rate of depression was noted in the low and high income groups, but not in the middle income group.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.S3 Table(DOCX)Click here for additional data file.


A dominant view holds that the outer and middle ear are the determining factors for the frequency dependence of mammalian hearing sensitivity, but this view has been challenged. In the ensuing debate, there has been a missing element regarding in what sense and to what degree the biophysics of the inner ear might contribute to this frequency dependence. Here, we show that a simple model of the inner ear based on fundamental physical principles, reproduces, alone, the experimentally observed frequency dependence of the hearing threshold. This provides direct cochlea modeling support of the possibility that the inner ear could have a substantial role in determining the frequency dependence of mammalian hearing. A deviant viewpoint emerges from a more recent analysis by Ruggero et al.3, who re-evaluating middle ear transfer function data, arrived at the result that a number of animal middle ear transfer functions appear to cover a much broader interval than their actual hearing frequency interval , an impedance matcher (middle ear), and a Fourier analyzer of the auditory signal (inner ear), respectively , described by fluid and BM mass density, depth of the cochlear fluid canal, BM stiffness and surface tension. To these passive properties, active amplification found in the cochlea is added in the form of outer hair cell dynamics described at a mesoscopic level26 in terms of the Hopf small signal amplifier property31. A micro-electro-mechanical model of the embedded hair cell dynamics, that would account for the whole mammalian hearing range, is presently still missing. This, however, is not detrimental since the underlying Hopf small-signal amplifier model, which has been demonstrated to be the working principle of several animal’ hearing’ implementations , can naturally be implemented into the biophysical framework and can directly serve for implementing the biophysically observed amplification response.The biophysically detailed differential equation model of the cochlea that we use below to address this questionμ . Detailed comparisons of biophysical key data to the corresponding data from the Hopf cochlea, were provided in earlier publications40 that would be compatible with a cochlea where all Hopf parameters have the same value (a “flat-tuned” cochlea) on a logarithmic frequency spacing. The fact that animals of variable sizes  have substantial lower hearing frequency bounds compared to humans, points to tuning as an expression of evolutionary adaptation of the different species, rather than to limitations contributed by the mechano-electrical OHC and hair bundle design. Additionally, species-specific emphasized frequency intervals may be due to neural conditioning, by which efferent connections may be designed or taught to enhance or to suppress desired and undesired, respectively, frequency ranges39. An observed gentle decay of the endocochlear potential along the cochlear duct is observed , or by the tuning of the sensitivity of the amplifiers. In the context of the mesoscopic approach followed in our modeling, a tuning of the sensitivity is the simpler solution. In the following, we used a tuning suggested by the estimate provided in ref. 43 pitch shift experiments15. Upon such tuning, previous observations regarding local amplification, combination tone decay, phase behavior procession along the cochlea, and sound selectivity by tuning15, remain valid , reaches at the node above a −50 dB threshold (the model’s hearing threshold). Other choices of the threshold within a ±10 dB bandwidth . From a range between −120 and −10 dB, stimulation levels were selected in steps of 1 dB, at stimulation frequencies from a  kHz interval, using logarithmic spacing. At each section, the response y denotes the maximal amplitude of the response obtained during the observation time. The input level for which the maximum Rmax across all sections was closest to −50 dB, was taken as the hearing threshold input level.To place our model into the context of psychoacoustic hearing experiments, we start from the following: if for the cochlea a Hopf parameter around μ at −0.1 for the first few sections (coding for the highest frequencies), followed by a steady decrease of −0.0105 per section, was used . Also neighboring configurations were tested (e.g. where an immediate decay was implemented); all of them reproduced the experimental audiogram from ref. For our main experiments, a Hopf cochlea with 31 sections, spanning 110–19912 Hz, tuned at Hopf parameters 26 corroborates that salient effects of the BM attachment are basal to the characteristic locus of our first amplifier , third box. Beyond the characteristic frequency of the last amplifier, the amplification vanishes therefore more abruptly than in the biological example, and it is also known that towards the apex, the membrane vibrations are less sharply tuned46. Toward the physical end of the basilar membrane, also other salient effects are neglected, in particular the vanishing pressure difference between the scala media and the scala tympani that must be expected to have a strong effect on the biological response. We suspect that if that frequency region could be accessed experimentally (a quite difficult endeavor47), a precipitous rise of the curve would be observed. Reliable data, however, are sparse also in this case.The deviations between psychoacoustic measurements and estimates and our simulation results have the following natural explanations  = aeiϕ is constant in this coordinate frame, and one can obtain a cubic polynomial in a2 that can be solved for the real amplitude a45. Alternatively, one can separate the locking criterion into two conditions ω, but from the second, assuming ωch − ω|, we can approximateμ and small forcing F . For input frequency a ≈ F. This defines a natural limit for the number of higher frequency Hopf cochlea sections that most significantly influence the amplification cascade of an input signal .The above interpretation can be corroborated by analytical considerations that, moreover, nicely exhibit the fundamental mechanism by which the frequency dependence of the hearing threshold is obtained in our model. The complex-number normal form Hopf equation, rescaled by a characteristic angular frequency In this way, essential frequency dependence of the hearing threshold emerges from a neighborhood preceding and including the signal frequency’s best matching amplifier. This neighborhood delivers the principal part of the amplification, where the asymmetry in frequency cf. Fig.  is the c49 and how this translates to the mesoscopic approach50 are of great interest themselves, our mesoscopic cochlea model embraces both effects within its Hopf section. The model reproduces to great accuracy not only the naturally measured local nonlinearities38 and ensuing salient nonlinear phenomena of hearing (such as the perception of pitch), but also the measured psychoacoustic hearing threshold’s dependence on frequency. On this mesoscopic level, we see strong evidence for a potential essential role of the inner ear in determining the sensitivity dependence of mammalian hearing. While our model is composed of identical amplifiers , it is their nonlinear interaction that binds the cochlea towards having its specific, biophysically and psycho-acoustically observed frequency-specific sensitivity. This uncovered feature is, on a more global scale of the cochlea, an even more fundamental manifestation of nonlinearity in hearing, compared to the fact that for signals composed of different frequencies, combination tone avalanches emerge . On a more general level, the approach taken here may open up new perspectives for research and engineering in the field of sensors. As one example, our analytical approximation to the full nonlinear-physics based model of the cochlea, reveals “filters” of a very particular form and enormous spatially extended overlaps. A classical engineer would hardly come up with such a design that poses a significant paradigm challenge to the conventional state of art. In the field of hearing, our modeling approach might provide insight into questions that are inaccessible to current experimental techniques, by guiding towards the formulation of closely related problem statements that can be experimentally accessed.While the questions of how the microscopic mechano-electromotile systems co-operate to arrive at the Hopf propertycf. ref. . Our rescf. ref. . This ha51, while it clearly affected the outer ear. In this light, while the inner ear should not be seen as the only relevant part, it seems that, as the evolutionarily less variable construction, it has the dominant role for shaping the hearing threshold. In either case, our results strongly suggest that the various statements in textbooks exhibiting that hearing sensitivity is generally determined by the outer and middle ear (but not by the inner ear), may be historically biased and not be fully justified.The question whether the outer-middle or the inner ear provides the limiting factor of the hearing, might, in our view, be wrongly posed after all. If we admitted that the inner ear is sufficient for explaining frequency sensitivity, could we conclude that the outer and middle ear have  a minor role in shaping the hearing threshold? Obviously, evolution may occasionally have shaped ear canal and outer ear resulting in a constraint of hearing sensitivity. However, even the evolutionary adaption from today’s land-based towards water-based mammals did not substantially affect the cochlear construction principleSupplement


P < 0.001) and a higher prevalence of hens with poor plumage condition at 62 weeks of age  compared with T flocks. The prevalence of hens with keel bone deviations, with both keel bone fractures and deviations and with body wounds, was higher in NT flocks compared with T flocks at both ages (P < 0.001). Accumulated mortality from placement to end of production tended to be higher in NT flocks compared with T flocks . The prevalence of keel bone damage was higher among hens with poor plumage condition than hens with moderate/good plumage condition . Thus, omitting beak trimming had negative consequences for the condition of plumage, skin, and keel bone, and tended to increase mortality, highlighting the risk of reduced welfare when keeping layers with intact beaks. In addition, injurious pecking damage was found to be positively linked to keel bone damage. The causal relation is unknown, but we propose that fearfulness is an important factor.Beak trimming is used worldwide as a method of reducing the damage to feathers and skin caused by injurious pecking in laying hens. However, beak trimming also causes some welfare issues as trimming the beak results in pain and sensory loss. Due to this dilemma, there is an ongoing discussion in several European countries about whether to ban beak trimming. In this study, we investigated the welfare consequences of keeping layers with intact beaks and examined for links between injurious pecking damage and keel bone damage on an individual level. A study was conducted on 10 commercial farms housing laying hens in the barn system. Each farm participated with a flock of beak-trimmed hens (T) and a flock of non-trimmed (NT) hens that were visited around 32 and 62 weeks of age. During visits, the condition of plumage, skin, feet, and keel bone of 100 hens was assessed. Mortality was recorded by the producers. NT flocks had a lower prevalence of hens with good plumage condition around 32 weeks of age (94.1 vs. 99.6%,  Beak trimming is used worldwide as a method of reducing the damage caused by injurious pecking in laying hens. Injurious pecking, i.e., damaging pecking at feathers and skin, has been associated with poor welfare in terms of pain  and incrAlthough beak trimming is performed with the purpose of avoiding these welfare problems, it causes welfare issues itself. The beak of a laying hen is well innervated and contains nociceptors (sensation of pain), thermoreceptors (sensation of temperature), and mechanoreceptors (sensation of pressure and texture) . Beak trDue to this dilemma, there is an ongoing discussion in several European countries about whether to ban the beak trimming procedure, and in some countries , it is already banned, or a ban will be enforced in near future . Following this trend, the trade organisation for the egg sector in Denmark, the Danish Egg Association, decided to omit beak trimming in caged layers from July 2013 and in barn and free-ranging layers from July 2014. This means that presently, all laying hens in Denmark have intact beaks, a voluntary decision made by the egg sector, as beak trimming is still permitted by law.Few on-farm studies have been published on the welfare consequences of omitting beak trimming in laying hens. These studies focus on injurious pecking and the accompanying damage, particularly plumage damage and mortality. Most of the studies of flocks of non-trimmed hens find a negative impact on at least one of the welfare indicators investigated, e.g., increased prevalence of plumage damage –14, an iDifferent characteristics of floor feathers, i.e., feathers dropped onto the floor either due to moulting or plucking from the birds, have previously been found to be valid welfare indicators used in relation to feather pecking. For instance, prevalence of floor feathers with pecking damage has been found to be correlated positively with feather eating and feather pecking, measured as prevalence of droppings with feather content and poor plumage condition, respectively . FurtherOther welfare indicators may be affected by a change in the prevalence or impact of injurious pecking. In addition to the plumage, damaging pecking may also be directed towards the skin, including the skin of toes and combs , 20, andHigh prevalence of keel bone fractures is commonly found in commercial flocks of laying hens –31. KeelThe aims of this study were twofold. The first aim was to investigate the welfare consequences of keeping barn layers with intact beaks on commercial farms. Specifically, we investigated the effects of beak treatment (trimmed vs. non-trimmed) on the condition of plumage, skin, keel bone, and feet as well as on the floor feather characteristics in barn layers. We expected to find an increase in damage to the plumage and skin in flocks of hens with intact beaks due to the increase in damaging impact which an intact beak may have compared with a trimmed beak. This was expected to be reflected in more pecking damage to the floor feathers. Furthermore, the density of floor feathers and proportion of short (downy) feathers were expected to be lower in the non-trimmed flocks, possibly due to increased activity or arousal levels. The second aim was to determine any links between injurious pecking damage and keel bone damage on an individual level. We predicted that there would be a positive link between poor condition of the flight feathers and keel bone fractures on an individual level.2 and with no outdoor access. The flock sizes ranged between 2,000 and 13,000 . The distribution of flocks on housing systems (single- or multitiered) and hybrids  is presented in Table A cross-sectional study was conducted from April 2013 to June 2016 on commercial farms housing laying hens in the barn system. The barns system in Denmark consists of either single-tiered percheries or multitiered aviaries. The participating producers were originally recruited for another research project , 33; 10 ® protocol  and deviations of keel bones were assessed by palpation. In the HealthyHens scoring protocol, the caudal tip of the keel bone is scored separately from the rest of the keel bone. Due to uncertainty at the commencement of the study about the validity of assessing fractures at the caudal tip by use of palpation, we decided not to include the lower 2 cm of the keel bone. This means that we only registered fractures that were likely to have been caused by a trauma see . Prevale2) of the house was counted. The areas were randomly selected by walking 15 steps in a straight line (where possible) in different directions between areas. Following the last step, a frame (1 m × 1 m) was gently thrown, and feathers within the frame were counted. During the visit at 62 weeks of age, all feathers (T: n = 629 and NT: n = 190) from these 10 areas were collected for later examination. At the visit at 62 weeks of age, droppings (n = 100 per flock) were equally collected from different areas in the house. Both feathers and droppings were stored at −18°C until later examination. The feathers and droppings were examined according to the methods described by Riber and Hinrichsen , with the exception of one farmer who culled one of the study flocks at 62 weeks of age. In addition, two farmers provided information about daily feed and water consumption as well as daily egg production, which was used to calculate average daily production/consumption per hen in weeks 32 and 62 of age using data for those 2 weeks, respectively.All statistical analyses were conducted in R version 3.1.3  using thThe effect of beak treatment was investigated on (a) clinical welfare indicators  at 32 and 62 weeks, (b) the percentages of droppings with feather content at 62 weeks, (c) density of floor feathers at 62 weeks, and (d) floor feather characteristics (length and damage due to feather pecking) at 62 weeks.2-test for the overall effect of beak treatment (T and NT) and in proportion tests to analyse if the prevalence of the different categories differed between T and NT flocks. The body weight at 62 weeks of age was analysed using a paired t-test for the nine farms (excluding the farm with two different hybrids).The SKAP system  as well n = 52 and NT: n = 50). Data on floor feathers were missing from two farms.Data on feather length and density of floor feathers were analysed using a linear regression model, and density of floor feathers was log transformed. The remaining variables  were analysed using a logistic regression model. The regression models for the body wounds and foot injuries included age (32 and 62 weeks) of the hens and the interaction between beak treatment and age. However, the variable hyperkeratosis was analysed separately for 32 and 62 weeks of age due to converging issues of the interaction model. Broken feathers were excluded from the analyses due to uncertainty of time (before/after collection) and cause of the breakage  were kept under comparable conditions, e.g., similar housing system, hybrid and management. The only exception was one farm using different hybrids in the two flocks. However, models including and excluding this farm resulted in the same conclusions. Furthermore, we tested if models including a random effect of hybrid nested in farm explained more of the variation. The conclusion was that the model including only farm as a random effect was the most suitable model for the dataset. The effect of housing system was not tested in the models as only three farms had a single-tiered housing system. However, as the pairwise comparisons were done only for flocks from the same farm, i.e., flocks of the same hybrid reared in the same housing system, the effect of hybrid and housing system is included in the random effect of farm. All results from the regression models are presented as model probabilities (logistics) or model estimates (linear) and standard error. Results are presented as back-transformed estimates and raw SE.Mortality was analysed using the Wilcoxon Signed Rank test with paired samples for farms reporting accumulated mortality until the end of production (>70 weeks), i.e., six farms. Data from the paired flocks, i.e., flocks originating from the same farm, were always extracted from the same age period .2 contingency table test of the data collected at 62 weeks of age . In the tests for correlations on an individual level, the beak treatment was not taken into account.Tests for correlations on an individual level between different welfare indicators  were done using a χAn overall difference in plumage condition  was found between T and NT flocks for both ages Table . At 32 wLikewise, an overall difference in flight feather condition  was found between T and NT flocks for both ages Table . At 32 wAn overall effect of beak treatment was found at the two ages on occurrences of keel bone damage Table . No diffThe results from the assessment of feathers collected on top of the litter at 62 weeks of age are shown in Table Table V = 21, P = 0.03) with higher mortality in NT flocks compared with T flocks. The mean mortality in NT flocks was 18.7% (farm range: 7.2–41.0%) and in T flocks 13.6% (farm range: 4.2–38.5%). One farm experienced very high mortality in both flocks . If this farm was excluded from the analysis, the mortality tended to be higher in NT flocks compared with T flocks , with the mean mortality in NT flocks being 14.2% (farm range: 7.1–21.0%) and in T flocks 8.6% (farm range: 4.2–14.1%). At 62 weeks of age, the average body weight of the hens was higher in T flocks  compared with NT flocks  .Accumulated mortality from placement to end of production differed between T and NT flocks . Likewise, the prevalence of keel bone damage  was higher among hens with poor plumage condition than hens with moderate/good plumage condition . The prevalence of hens with keel bone damage  was higher among hens with injurious pecking damage  compared to hens without injurious pecking damage .The prevalence of body wounds was higher among hens with poor plumage condition compared with hens with moderate/good plumage condition . No difference was found between hens with good condition of the flight feathers and hens with poor flight feathers in the prevalence of keel bone fractures . A similar result was found with regard to keel bone deviation .Looking specifically at the links between the condition of the flight feathers and the other welfare indicators, we found that the majority of hens (73.1%) having a poor flight feather condition also had a poor condition of the remaining feathered parts of the body , whereas only 15.5% of the hens having good flight feather condition had poor condition of the remaining feathered parts of the body  compared with non-trimmed hens at 62 weeks of age. Normally, the procedure of beak trimming has either a temporary negative effect or no effect on body weight gain –46. TherOther welfare indicators were affected by beak treatment. The prevalence of body wounds were higher in NT flocks and the mortality also tended to be higher in NT flocks, indicating more injurious pecking that either directly or indirectly may have resulted in cannibalism. A higher mortality in NT flocks has been found in previous on-farm studies of laying hens , 49. We vice versa) than a hen with a good/moderate plumage condition and no skin damage. This is in accordance with the results found by Donaldson et al.  and floor feathers indicate increased movements or sudden escape behaviour/flightiness in the non-trimmed flocks where high levels of plumage damage were found. The density of floor feathers was lower in NT flocks, but the feathers were longer and had more damage compared with T flocks. As the hens in the NT flocks did not ingest the feathers, assessed from the finding of a similar prevalence of droppings with feather content in the two beak treatments, but still had a considerable higher prevalence of poor plumage condition, feathers must have disappeared somehow else from the floor. The prevalence of downy floor feathers was much lower in NT flocks compared with T flocks, indicating that the feathers disappearing were the short light downy ones. As proposed previously , this coThe direction of the relation between injurious pecking damage and keel bone damage is unknown. Above, we have argued how a poor plumage condition indirectly may result in keel bone damage. However, the opposite scenario is also possible. A hen with a good plumage condition who fractures her keel bone may show a change in behaviour, e.g., in terms of increased inactivity , 60. A pIt is well known that injurious pecking results in reduced welfare in terms of pain and fear due to the tearing of feathers and tissue –3. In adAll procedures involving animals were approved by the Danish Animal Experiments Inspectorate in accordance with the Danish Ministry of Justice Law no. 382  and Acts 333 , 726 , and 1016 .AR conceived the idea of the project, raised funding, and collected the data. LH did the statistical analyses. The manuscript was prepared, edited, and approved by both authors.The authors declare that the work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.