A signal processing tool for extracting features from arterial blood pressure and photoplethysmography waveforms

Arterial blood pressure (ABP) and photoplethysmography (PPG) waveforms contain valuable clinical information and play a crucial role in cardiovascular health monitoring, medical research, and managing medical conditions. The features extracted from PPG waveforms have various clinical applications ranging from blood pressure monitoring to nociception monitoring, while features from ABP waveforms can be used to calculate cardiac output and predict hypertension or hypotension. In recent years, many machine learning models have been proposed to utilize both PPG and ABP waveform features for these healthcare applications. However, the lack of standardized tools for extracting features from these waveforms could potentially affect their clinical effectiveness. In this paper, we propose an automatic signal processing tool for extracting features from ABP and PPG waveforms. Additionally, we generated a PPG feature library from a large perioperative dataset comprising 17,327 patients using the proposed tool. This PPG feature library can be used to explore the potential of these extracted features to develop machine learning models for non-invasive blood pressure estimation.

Vitamin D supplementation and clinical outcomes in COVID-19: a systematic review and meta-analysis

PURPOSE

To provide a precise summary and collate the hitherto available clinical evidence on the effect of vitamin D supplementation on clinical outcomes in COVID-19 patients.

METHODS

PubMed/MEDLINE, Scopus, and Web of Science databases were systematically searched using appropriate keywords till June 8, 2021, to identify observational studies and randomized controlled trials (RCTs) reporting adverse clinical outcomes (ICU admission and/or mortality) in COVID-19 patients receiving vitamin D supplementation vs. those not receiving the same. Both prior use and use of vitamin D after COVID-19 diagnosis were considered. Unadjusted/adjusted pooled odds ratio (OR) with 95% confidence intervals (CI) were calculated (PROSPERO registration number CRD42021248488).

RESULTS

We identified 13 studies (10 observational, 3 RCTs) pooling data retrieved from 2933 COVID-19 patients. Pooled analysis of unadjusted data showed that vitamin D use in COVID-19 was significantly associated with reduced ICU admission/mortality (OR 0.41, 95% CI: 0.20, 0.81, p = 0.01, I2 = 66%, random-effects model). Similarly, on pooling adjusted risk estimates, vitamin D was also found to reduce the risk of adverse outcomes (pooled OR 0.27, 95% CI: 0.08, 0.91, p = 0.03, I2 = 80%, random-effects model). Subgroup analysis showed that vitamin D supplementation was associated with improved clinical outcomes only in patients receiving the drug post-COVID-19 diagnosis and not in those who had received vitamin D before diagnosis.

CONCLUSIONS

Vitamin D supplementation might be associated with improved clinical outcomes, especially when administered after the diagnosis of COVID-19. However, issues regarding the appropriate dose, duration, and mode of administration of vitamin D remain unanswered and need further research.

Fracture risk in hypoparathyroidism: a systematic review and meta-analysis

In this meta-analysis, we analyzed 7 observational studies for assessing the fracture risk in patients with hypoparathyroidism (hypoPT). We found that the risk of vertebral fractures is increased by almost 2-fold, especially those with nonsurgical hypoPT.

PURPOSE

Patients with hypoPT have higher bone mineral density than age- and sex-matched controls. This would theoretically translate into a lower risk of fractures, although available clinical evidence is contradictory. Hence, the present systematic review and meta-analysis was undertaken to collate and provide a precise summary of fracture risk in hypoPT.

METHODS

PubMed, Scopus, and Web of Science databases were systematically searched using appropriate keywords till March 8, 2021, to identify observational studies reporting the rate of occurrence of fractures among hypoPT patients (nonsurgical and/or postsurgical) compared to non-hypoPT subjects (controls). Study quality was assessed using Newcastle-Ottawa Scale. Pooled odds ratio (OR) with 95% confidence intervals (CI) was calculated. Subgroup analyses of nonsurgical and postsurgical hypoPT patients were also conducted.

RESULTS

We identified 7 observational studies of high-quality pooling data retrieved from 1470 patients with hypoPT. When stratified based on the skeletal site, pooled analyses showed that hypoPT patients were at an increased risk of vertebral fractures compared to non-hypoPT controls (OR 2.22, 95% CI: 1.23, 4.03, p = 0.009, I² = 49%, random-effects model). The increased risk of vertebral fractures was seen only in patients with nonsurgical hypoPT (OR 2.31, 95% CI: 1.32, 4.03, p = 0.003, I² = 3%, random-effects model) but not in those with postsurgical hypoPT. hypoPT patients were not at an increased or decreased risk of any, humerus, or proximal femur/hip fractures than controls.

CONCLUSIONS

Nonsurgical hypoPT patients are at an almost 2-fold increased risk of vertebral fractures and thus need to be actively screened irrespective of the underlying BMD.

Primary hyperparathyroidism in pregnancy: observations from the Indian PHPT registry

PURPOSE

To present the data on primary hyperparathyroidism (PHPT) in pregnancy from India obtained from a large database maintained over 15 years.

METHODS

We retrieved data of all women with gestational PHPT from the Indian PHPT registry between July 2005 and January 2020, and compared their clinical, biochemical, and other characteristics with age-matched non-pregnant women with PHPT.

RESULTS

Out of 386 women, eight had gestational PHPT (2.1%). The common presenting manifestations were acute pancreatitis (50%) and renal stone disease (50%); two were asymptomatic. Five women (62.5%) had a history of prior miscarriages. Seven patients (88%) had preeclampsia during the present gestation. Serum calcium and intact parathyroid hormone (iPTH) were not statistically different from the age-matched non-pregnant PHPT group. Six patients with mild-to-moderate hypercalcemia were medically managed with hydration with/without cinacalcet while one patient underwent percutaneous ethanol ablation of the parathyroid adenoma; none underwent surgery during pregnancy. Mean serum calcium maintained from treatment initiation till delivery was 10.5 ± 0.4 mg/dl. One patient had spontaneous preterm delivery at 36 weeks; the remaining patients had normal vaginal delivery at term. None had severe preeclampsia/eclampsia. Fetal outcomes included low birth weight in three newborns (37.5%); two of them had hypocalcemic seizures.

CONCLUSION

The prevalence of gestational PHPT was 2.1% in this largest Indian PHPT cohort, which is higher than that reported from the West (< 1%). Gestational PHPT can lead to preeclampsia and miscarriage. Pregnant PHPT patients with mild-to-moderate hypercalcemia can be managed with hydration/cinacalcet; however, long-term safety data and large-scale randomized controlled trials are required.

Hansen's disease in the era of COVID-19: An observation on a series of six patients with co-infection

Since the onset of the present pandemic, effect of the novel corona virus on other infectious conditions continues to be investigated. Although the immunological responses to SARS‐Cov‐2 infection have been elaborated extensively, they fail to explain, variations in its clinical manifestations and its interaction with other diseases. Hansen's disease is known to present as a complex immunological response to the lepra bacilli, resulting in its varied spectral manifestations. An interaction between these two infectious agents, hence, may affect Hansen's disease. We came across six cases of Hansen's disease who developed COVID19 co‐infection. This series presents their clinical course and outcome, during the period of co‐infection. All cases were followed up for a minimum eight‐week period thereafter. In all these cases the active phase of coronavirus infection had no effect on Hansen's disease and those on prednisolone for their lepra reaction had a more favorable outcome, with two cases manifesting exacerbation of their lepra reactions in the follow period.

Current Status of Indications, Timing, Management, Complications, and Outcomes of Tracheostomy in Traumatic Brain Injury Patients

Tracheostomy is the commonest bedside surgical procedure performed on patients needing mechanical ventilation with traumatic brain injury (TBI). The researchers made an effort to organize a narrative review of the indications, timing, management, complications, and outcomes of tracheostomy in relation to neuronal and brain-injured patients following TBI. The study observations were collated from the published literature, namely original articles, book chapters, case series, randomized studies, systematic reviews, and review articles. Information sorting was restricted to tracheostomy and its association with TBI. Care was taken to review the correlation of tracheostomy with clinical correlates including indications, scheduling, interventions, prognosis, and complications of the patients suffering from mild, moderate and severe TBIs using Glasgow Coma Scale, Glasgow Outcome Scale, intraclass correlation coefficient, and other internationally acclaimed outcome scales. Tracheostomy is needed to overcome airway obstruction, prolonged respiratory failure and as indispensable component of mechanical ventilation due to diverse reasons in intensive care unit. Researchers are divided over early tracheostomy or late tracheostomy from days to weeks. The conventional classic surgical technique of tracheostomy has been superseded by percutaneous techniques by being less invasive with lesser complications, classified into early and late complications that may be life threatening. Additional studies have to be conducted to validate and streamline varied observations to frame evidence-based practice for successful weaning and decannulation. Tracheostomy is a safer option in critically ill TBI patients for which a universally accepted protocol for tracheostomy is needed that can help to optimize indications and outcomes.

A dataset for systematic testing of crackle separation techniques

Pulmonary crackles are indicative of lung pathology and may be used for diagnosis and monitoring of disease. Many algorithms have been proposed to separate the crackle sounds from the breath noise, but a lack of standardized processes for evaluating their performance makes comparisons difficult. In this paper we propose a standard data set to be used for systematic comparative testing.

Investigation of 220Rn emanation and exhalation from soil samples of Larsemann Hills region, Antarctica

In the present study, thoron exhalation flux density were measured in the soil samples collected around the Indian station namely Bharati (69° 24.41' S, 76° 11.72' E) and its nearby islands in the Larsemann hills region of Antarctica. Further, dependency of thoron mass emanation rate and emanation coefficient on the soil grain size was studied by segregating the soil samples into four different grain size groups: 50-100 μm, 100-200 μm, 200-500 μm and 500-1000 μm which showed that both of them follow a decreasing trend with increase in grain size. A comparison of measured mass emanation rate between different soil samples showed that it had a larger variation for the smaller grain size which eventually decreased as grain size increased while emanation coefficient was observed to be nearly constant for all the grain size groups. The variation in emanation coefficient with respect to mean grain size has been investigated and an empirical exponential model has been proposed for predicting emanation coefficient for different grain sizes.

Holographic projection for multispot structured illumination microscopy

This paper describes the design and testing of a multispot structured illumination microscopy system using computer-generated holograms to create the required excitation patterns. Furthermore, it demonstrates the use of an adapted direct search algorithm for calculating the holograms that allows for imaging across an extended field of view. The system was tested on fixed targets and live cells yielding a two times resolution increase over conventional diffraction-limited imaging. LAY DESCRIPTION: We present the design and testing of a multispot structured illumination microscopy system using computer-generated holograms to create the required excitation patterns. It demonstrates the use of an adapted direct search algorithm for calculating the holograms that allows for imaging across an extended field of view. The system was tested on fixed targets and live cells yielding a two times resolution increase over conventional diffraction-limited imaging. The results here demonstrate that holography provides an efficient means of pattern projection for MSIM imaging. It provides a significant improvement in the efficiency of pattern projection and more importantly it allows for the testing of more diverse excitation patterns than possible with amplitude-only projection. For example, PSF engineering using phase modulation can be easily incorporated into the calculated holograms, potentially generating subdiffraction structures in the excitation pattern. The ability to incorporate PSF engineering into SIM opens up holographic MSIM as a potential method for further increasing resolution with little or no change to the imaging system.

Correlates of Vitamin a Deficiency among Indian Rural Preschool-Age Children

Purpose

In India, 52,000 children go blind every year on account of vitamin A deficiency. The purpose of the study was determine the correlates of vitamin A deficiency among 4,205 preschool-age children.

Methods

Case-control study in Bihta Primary Health Center area, Bihar, India. Main outcome measures were dietary habits, maternal literacy, and birth order.

Results

Vitamin A deficiency was found to be significantly higher (p<0.01) in children on a vegetarian diet (7.14%) (OR 5.32). Children born to a literate mother had a prevalence of only 1.35% in relation to a corresponding value of 4.11% in children born to illiterate mothers (p<0.01) (OR 3.15). Birth order of preschool-age children was significantly related to vitamin A deficiency. In birth order less than or equal to three, the prevalence was 2.81%, in comparison to those with birth order four or more, in whom the magnitude was significantly higher (p<0.01) at 5.61% (OR 2.08).

Image scanning microscopy: an overview

For almost a century, the resolution of optical microscopy was thought to be limited by Abbé's law describing the diffraction limit of light. At the turn of the millennium, aided by new technologies and fluorophores, the field of optical microscopy finally surpassed the diffraction barrier: a milestone achievement that has been recognized by the 2014 Nobel Prize in Chemistry. Many super-resolution methods rely on the unique photophysical properties of the fluorophores to improve resolution, posing significant limitations on biological imaging, such as multicoloured staining, live-cell imaging and imaging thick specimens. Structured Illumination Microscopy (SIM) is one branch of super-resolution microscopy that requires no such special properties of the applied fluorophores, making it more versatile than other techniques. Since its introduction in biological imaging, SIM has proven to be a popular tool in the biologist's arsenal for following biological interaction and probing structures of nanometre scale. SIM continues to see much advancement in design and implementation, including the development of Image Scanning Microscopy (ISM), which uses patterned excitation via either predefined arrays or raster-scanned single point-spread functions (PSF). This review aims to give a brief overview of the SIM and ISM processes and subsequent developments in the image reconstruction process. Drawing from this, and incorporating more recent achievements in light shaping (i.e. pattern scanning and super-resolution beam shaping), this study also intends to suggest potential future directions for this ever-expanding field.

Innate and humoral recognition of the products of cell death: differential antigenicity and immunogenicity in lupus

While apoptotic debris is believed to constitute the original antigenic insult in lupus (which is characterized by a time-dependent diversification of autoreactivity), whether such debris and autoantibodies specifically recognizing its constituents mediate differential effects on innate and humoral responses in lupus-prone mice is currently unknown. Apoptotic blebs (as opposed to cellular lysate) enhanced preferentially the maturation of dendritic cells (DCs) from bone marrow precursors drawn from lupus-prone mice. Murine, somatically mutated, apoptotic cell-reactive immunoglobulin (Ig)G monoclonal antibodies demonstrated enhanced recognition of DCs and also displayed a prominent lupus strain-specific bias in mediating DC maturation. Further, immunization of such antibodies specifically in lupus-prone mice resulted in widespread humoral autoreactivity; hypergammaglobulinaemia (a hallmark of systemic autoimmunity) was observed, accompanied by enhanced antibody titres to cellular moieties. Induced antibodies recognized antigens distinct from those recognized by the antibodies employed for immunization; in particular, nephritis-associated anti-double stranded (ds) DNA antibodies and neonatal lupus-associated anti-Ro60 antibodies were elicited by a non-dsDNA, non-Ro60 reactive antibody, and Sm was a favoured target. Further, only in lupus-prone mice did such immunization enhance the kinetics of humoral anti-self responses, resulting in the advanced onset of glomerulosclerosis. These studies reveal that preferential innate and humoral recognition of the products of cell death in a lupus milieu influence the indices associated with autoimmune pathology.

A descriptive model of resting-state networks using Markov chains

Resting-state functional connectivity (RSFC) studies considering pairwise linear correlations have attracted great interests while the underlying functional network structure still remains poorly understood. To further our understanding of RSFC, this paper presents an analysis of the resting-state networks (RSNs) based on the steady-state distributions and provides a novel angle to investigate the RSFC of multiple functional nodes. This paper evaluates the consistency of two networks based on the Hellinger distance between the steady-state distributions of the inferred Markov chain models. The results show that generated steady-state distributions of default mode network have higher consistency across subjects than random nodes from various RSNs.

Perioperative factors associated with acute kidney injury after partial nephrectomy

BACKGROUND

Partial nephrectomy is performed with the aim to preserve renal function. But the occurrence of postoperative acute kidney injury (AKI) can interfere with this goal. Our primary aim was to evaluate associations between pre-specified modifiable factors and estimated glomerular filtration rate after partial nephrectomy. Our secondary aims were to evaluate associations between pre-specified modifiable factors and both serum creatinine concentration and type of nephrectomy.

METHODS

The records of 1955 patients who underwent partial nephrectomy were collected. Postoperative estimated glomerular filtration rate (eGFR) was used as the primary outcome measure. Twenty modifiable risk factors were studied. A repeated-measures linear model with autoregressive within-subject correlation structure was used. The interaction between all the factors and type of nephrectomy was also studied.

RESULTS

A total of 1187 (61%) patients had no kidney injury, 647 (33%) had stage I, 80 (4%) had stage II, and 41 (2%) had stage III injury. The mean eGFR increased an estimated 0.83 (99.76% CI 0.79-0.88) ml min(-1) 1.73 m(-2) for a unit increase in baseline eGFR. Mean eGFR was 2.65 (99.76% CI: 0.13, 5.18) ml min(-1) 1.73 m(-2) lower in patients with hypertension. Mean eGFR decreased 0.42 (99.76% CI: 0.22, 0.62) ml min(-1) 1.73 m(-2) for a 10-minute longer in duration of procedure and decreased 2.09 (99.76% CI: 1.39, 2.80) ml min(-1) 1.73 m(-2) for a 10-minute longer in ischemia time. It was 3.53 (99.76% CI: 0.83, 6.23) ml min(-1) 1.73 m(-2) lower for patients who received warm ischemia as compared to cold ischemia.

CONCLUSION

Potentially modifiable factors associated with AKI in the postoperative period were identified as baseline renal function, preoperative hypertension, longer duration of surgical time and ischaemia time, and warm ischaemia.

Elucidation of the potential disease-promoting influence of IgM apoptotic cell-reactive antibodies in lupus

The undigested remnants of apoptosis are believed to stimulate the generation of autoantibodies in lupus. The biological properties of initiator, disease-specific IgM antibodies that specifically recognize apoptotic cells, readily detected in the sera of lupus patients, remain unclear. Apoptotic cell-reactive IgM monoclonal antibodies (generated from lupus-prone mice), as opposed to control IgM, preferentially stimulated maturation of bone marrow-derived dendritic cells (BMDCs) derived from such mice, relative to BMDCs derived from healthy mice. An influence of both antibody specificity and cell genotype was also apparent in the secretion of signature inflammatory cytokines. Immunization of such antibodies in lupus-prone animals induced increases in total serum IgG levels, with the elicited antibodies also preferentially recognizing moieties on dying cells. An expanded specificity was apparent both upon Western blot on cellular lysate and from the enhanced recognition of dsDNA, Ro60, RNP68 and Sm; the antibody most efficient in mediating autoreactive diversity, while being germline encoded, also induced the highest degree of phenotypic changes on BMDCs. Apoptotic cell-reactive IgM antibodies may therefore be potentially capable of influencing the course of systemic autoimmune disease by affecting both innate and adaptive immunity.

Novel aminoalkyl tris-cyclometalated iridium complexes as cellular stains

Novel tris-cyclometalated luminescent iridium complexes capable of staining cells and showing in cellulo lifetimes in the microsecond regime are reported.

Cytoplasmic phospholipase A₂ modulation of adolescent rat ethanol-induced protein kinase C translocation and behavior

Ethanol consumption typically begins during adolescence, a developmental period which exhibits many age-dependent differences in ethanol behavioral sensitivity. Protein kinase C (PKC) activity is largely implicated in ethanol-behaviors, and our previous work indicates that regulation of novel PKC isoforms likely contributes to decreased high-dose ethanol sensitivity during adolescence. The cytoplasmic Phospholipase A2 (cPLA2) signaling cascade selectivity modulates novel and atypical PKC isoform activity, as well as adolescent ethanol hypnotic sensitivity. Therefore, the current study was designed to ascertain adolescent cPLA2 activity both basally and in response to ethanol, as well as it's involvement in ethanol-induced PKC isoform translocation patterns. cPLA2 expression was elevated during adolescence, and activity was increased only in adolescents following high-dose ethanol administration. Novel, but not atypical PKC isoforms translocate to cytosolic regions following high-dose ethanol administration. Inhibiting cPLA2 with AACOCF3 blocked ethanol-induced PKC cytosolic translocation. Finally, inhibition of novel, but not atypical, PKC isoforms when cPLA2 activity was elevated, modulated adolescent high-dose ethanol-sensitivity. These data suggest that the cPLA2/PKC pathway contributes to the acute behavioral effects of ethanol during adolescence.

Ethanol dose-dependently elicits opposing regulatory effects on hippocampal AMPA receptor GluA2 subunits through a zeta inhibitory peptide-sensitive kinase in adolescent and adult Sprague-Dawley rats

AMPA receptor GluA2 subunits are strongly implicated in cognition, and prior work suggests that these subunits may be regulated by atypical protein kinase C (aPKC) isoforms. The present study assessed whether hippocampal and cortical AMPA receptor GluA2 subunit regulation may be an underlying factor in known age-related differences to cognitive-impairing doses of ethanol, and if aPKC isoforms modulate such responses. Hippocampal AMPA receptor GluA2 subunit, protein kinase Mζ (PKMζ), and PKCι/λ expression were elevated during adolescence compared to adults. 1 h following a low-dose (1.0-g/kg) ethanol exposure, hippocampal AMPA receptor GluA2 subunit serine 880 phosphorylation was decreased in adolescents, but was increased in adults. Age-dependent changes in GluA2 subunit phosphorylation were paralleled by alterations in aPKC isoforms, and zeta inhibitory peptide (ZIP) administration prevented ethanol-induced increases in both in adults. Ethanol-induced changes in GluA2 subunit phosphorylation were associated with delayed regulation in synaptosomal GluA2 subunit expression 24 h later. A higher ethanol dose (3.5-g/kg) failed to elicit changes in most measures in the hippocampus at either age. Similar to the hippocampus, analysis of cerebral cortical tissue also revealed age-related declines. However, no demonstrable effects were found following a low-dose ethanol exposure at either age. High-dose ethanol exposure reduced adolescent GluA2 subunit phosphorylation and aPKC isoform expression that were again accompanied by delayed reductions in synaptosomal GluA2 subunit expression. Together, these results suggest that GluA2-containing AMPA receptor modulation by aPKC isoforms is age-, region- and dose-dependently regulated, and may potentially be involved in developmentally regulated ethanol-induced cognitive impairment and other ethanol behaviors.

An Overview of Cyanobacterial Exopolysaccharides: Features, Composition and Effects of Stress Exposure

Cyanobacterial polysaccharides have been topic of current research interests for quite some time. Most of the cyanobacteria are observed to secrete a somewhat slimy material which is either loosely bound to or released to the medium. These extracellular polysaccharidic materials are of high molecular weight and consist of either one or different sugar residues. The presence of more than one uronic acids and/or acetylated amino sugars, phosphate, lactate etc. are thought to be one of the main reasons of the structural complexity of these materials. The structural composition and productivity of cyanobacterial polysaccharides are usually changed during different stress exposure including aging. This unique property can play a vital role in the possible biotechnological exploitation in various fields. Though ample data are there, still there is a large gap between the information on hand and the technology needed to meet the demand of the industrial sectors on the other. In the current review article an attempt has been taken to compile the information available about the main features, structural composition, varied roles and to highlight the thrust areas in a detail approach.DOI: http://dx.doi.org/10.3126/ijls.v8i4.10891

Pattern and Determinants of Overweight and Obesity Among Future Physicians

Background   Overweight including obesity is a leading cause of present day morbidity and kills more people than underweight. Keeping this background in mind this study had been conducted to establish the pattern of overweight and obesity in the midst of undergraduate medical group and to find out the association of overweight (plump) and obesity with probable hazardous factors. Materials and Methods This descriptive observational study had been conducted among undergraduate medical group for the duration of May to June 2011. Simple random sampling was adopted to select the students under study. A pretested, predesigned self-administered questionnaire was utilized for data collection. Body Mass Index (BMI) was assessed through weight and height and acted as forecaster of heavy figure and or obesity. Overweight and or obesity were analyzed to see the association with certain socio-demographic variables, dietary habits, family history of overweight and or obesity, life style issues, computer use etc. After collection of data, these were analyzed using tabulation, proportion and Chi square through Epi-Info software. Results The study subjects were young adults. The general pattern of overweight (plump) and obesity was 18.0 percent and 4.0 percent respectively. Overweight and or obesity was found significantly high among male students, fast food and soft drinks takers, low takers of fruits and vegetables, alcohol consumers, students with lack of exercise and family history of obesity. Overweight and obesity were not found associated with type of diet (vegetarian or non-vegetarian) and smoking. Conclusion Presence of probable associated factors with regard to overweight (plump) and obesity exists amid medical undergraduate pupils.DOI: http://dx.doi.org/10.3126/nje.v4i1.10134 Nepal Journal of Epidemiology 2014;4 (1): 323-329

Ketamine is associated with lower urinary tract signs and symptoms

BACKGROUND

Case reports and series indicate that ketamine, an anesthetic agent, causes lower urinary tract symptoms (LUTS). This study explored whether ketamine users were more likely to report LUTS compared to other substance users.

METHODS

Participants were recruited through an online survey on erowid.org, a drug information website. A notice posted on the website invited substance users to participate in a web-based survey on "drug use and health". The notice did not mention ketamine, or other aspects of the research questions, to avoid participation bias. The anonymous survey collected demographics, drug use history, and history of LUTS (urinary frequency, urgency, incontinence, hematuria, and dysuria).

RESULTS

Of 18,802 participants, 18.7% and 5.8% reported ever (lifetime) and recent (past-6-month) use of ketamine, respectively. Prevalence of LUTS among ever, recent, and never users of ketamine were 28%, 30%, and 24% respectively. Multivariate analysis showed significant associations between recent ketamine use and urinary symptoms. For each additional day of ketamine use in the last 180 days, the odds of developing urinary frequency, urgency, dysuria, and hematuria increased by 1.6%, 1.4%, 1.7%, and 1.9% respectively. One excess case of urinary frequency was reported per 17 recent users of ketamine.

CONCLUSION

Compared to non-users, recent ketamine users had increased odds of LUTS. This is the first large-scale community-based study assessing the association of non-medical ketamine use with LUTS. Associations between ketamine and urological symptoms should be confirmed through longitudinal studies.

Fluorogenic tagging of protein 3-nitrotyrosine with 4-(aminomethyl)benzene sulfonate in tissues: a useful alternative to Immunohistochemistry for fluorescence microscopy imaging of protein nitration

Protein tyrosine nitration is a common biomarker of biological aging and diverse pathologies associated with the excessive formation of reactive oxygen and nitrogen species. Recently, we suggested a novel fluorogenic derivatization procedure for the detection of 3-nitrotyrosine (3-NT) using benzylamine derivatives to convert specifically protein- or peptide-bound 3-NT to a highly fluorescent benzoxazole product. In this study, we applied this procedure to fluorogenic derivatization of protein 3-NT in sections from adult rat cerebellum to: (i) test this method for imaging nitrated proteins in fixed brain tissue sections and (ii) compare the chemical approach to immunohistochemical labeling with anti-3-NT antibodies. Immunofluorescence analysis of cerebellar sections using anti-3-NT antibodies showed differential levels of immunostaining in the molecular, Purkinje, and granule cell layers of the cerebellar cortex; in agreement with previous reports, the Purkinje cells were most highly labeled. Importantly, fluorogenic derivatization reactions of cerebellar proteins with 4-(aminomethyl)benzene sulfonic acid (ABS) and K(3)Fe(CN)(6) at pH 9, after sodium dithionite reduction of 3-NT to 3-aminotyrosine, showed a very similar pattern of relative intensity of cell labeling and improved resolution compared with antibody labeling. Our data demonstrate that ABS derivatization may be either a useful alternative to or a complementary approach to immunolabeling in imaging protein nitration in cells and tissues, including under conditions of dual labeling with antibodies to cell proteins, thus allowing for cellular colocalization of nitrated proteins and any protein of interest.