Variable selection for discrete survival model with frailty in presence of left truncation and right censoring: Studying association of environmental toxicants on time-to-pregnancy

Understanding the association between mixtures of environmental toxicants and time-to-pregnancy (TTP) is an important scientific question as sufficient evidence has emerged about the impact of individual toxicants on reproductive health and that individuals are exposed to a whole host of toxicants rather than an individual toxicant. Assessing mixtures of chemical effects on TTP poses significant statistical challenges, namely (i) TTP being a discrete survival outcome, typically subject to left truncation and right censoring, (ii) chemical exposures being strongly correlated, (iii) appropriate transformation to account for some lipid-binding chemicals, (iv) non-linear effects of some chemicals, and (v) high percentage of concentration below the limit of detection (LOD) for some chemicals. We propose a discrete frailty modeling framework (named Discnet) that allows selection of correlated covariates while appropriately addressing the methodological issues mentioned above. Discnet is shown to have better and stable false negative and false positive rates compared to alternative methods in various simulation settings. We did a detailed analysis of the pre-conception endocrine disrupting chemicals and TTP from the LIFE study and found that older females, female exposure to cotinine (smoking), DDT conferred a delay in getting pregnant, which was consistent across various approaches to account for LOD as well as non-linear associations.     

Endodermal sinus tumour of stomach--a case report

This is a case report of an endodermal sinus tumour arising in the stomach of a 1 1/2 years male child. The tumour occupied full thickness of fundus and part of the body of the stomach. H&E sections of the tumour tissue showed endodermal sinus tumour with predominantly reticular and endodermal sinus patterns. Elevated level of alpha-fetoprotien was detected in the serum of the patient and within the tumour tissue by immunohistochemical technique.     

Disseminated nodular granulomatous perifolliculitis

Nodular granulomatous perifolliculitis is a well-recognized infection of the dermal and subcutaneous tissue caused by dermatophytes, which normally do not invade beyond the epidermis. We report here one such case that occurred in an immunosuppressed individual. The patient was a 35-year-old farmer who presented with small pruritic eruption that had initially appeared on the lower leg and then had gradually spread to hair-bearing areas of the body, finally producing nodular and pustular inflammatory lesions with exacerbations and remissions. Fungal examination by direct potassium hydroxide mount and culture revealed Trichophyton rubrum. Granulomatous changes were seen on histopathological examination. The patient completely responded to systemic antifungal therapy.     

A Bio-Inspired Multi-Population-Based Adaptive Backtracking Search Algorithm

Cognitive Computation - Backtracking search algorithm (BSA) is a nature-based optimization technique extensively used to solve various real-world global optimization problems for the past few...     

Role of tumor necrosis factor inhibitor in granulomatous interstitial nephritis secondary to Crohn’s disease

A 17-year-old male with attention deficit hyperactivity disorder was admitted to the hospital with generalized weakness. Vital signs and physical examination were normal. Laboratory data were notable for a creatinine of 4.5 mg/dL (baseline 0.6 mg/dL), estimated glomerular filtration rate of 18 ml/min/1.73 m² and hemoglobin 10 g/dL. Urinalysis revealed only 30 mg/dL protein. Serology for autoimmune workup was negative. Renal ultrasound was normal. Kidney biopsy showed noncaseating granulomas and acute on chronic tubulointerstitial nephritis (TIN) with lymphocytes, macrophages, plasma cells and no eosinophils. Acid fast bacilli and Grocott’s methenamine silver stains were negative. Granulomatous interstitial nephritis (GIN) was diagnosed. Prednisone at 60 mg/day was started and tapered. He was then noted to have diarrhea. Colonoscopy showed active enteritis with granulomatous inflammation consistent with Crohn’s disease (CD). Azathioprine was started but due to worsening renal function and diarrhea, it was discontinued. He did not tolerate continued higher doses of prednisone because of mood swings and cushingoid features. Infliximab was initiated with improvement in renal function. There was rapid worsening of renal function when infliximab therapy was interrupted but improved when both prednisone and inflixamb were reinitiated.     

High bone density masks architectural deficiencies in an individual with spinal cord injury

Context

Spinal cord injury (SCI) causes a decline of bone mineral density (BMD) in the paralyzed extremities via the gradual degradation and resorption of trabecular elements. Clinical tools that report BMD may not offer insight into trabecular architecture flaws that could affect bone''s ability to withstand loading. We present a case of a woman with a 30-year history of SCI and abnormally high distal femur BMD.

Findings

Peripheral quantitative-computed tomography-based BMD for this subject was ∼20% higher than previously published non-SCI values. Computed tomography (CT) revealed evidence of sclerotic bone deposition in the trabecular envelope, most likely due to glucocorticoid-induced osteonecrosis. Volumetric topologic analysis of trabecular architecture indicated that the majority of the bone mineral was organized into thick, plate-like structures rather than a multi-branched trabecular network. Visual analysis of the CT stack confirmed that the sclerotic bone regions were continuous with the cortex at only a handful of points.

Conclusions

Conventional clinical BMD analysis could have led to erroneous assumptions about this subject''s bone quality. CT-based analysis revealed that this subject''s high BMD masked underlying architectural flaws. For patients who received prolonged glucocorticoid therapy, excessively high BMD should be viewed with caution. The ability of this subject''s bone to resist fracture is, in our view, extremely suspect. A better understanding of the mechanical competency of this very dense, but architecturally flawed bone would be desirable before this subject engaged in activities that load the limbs.     

Gender and willingness to undergo invasive cardiac procedures

To explore the role of patient preferences in explaining gender differences in the use of invasive cardiac procedures, we surveyed 174 patients presenting for cardiac stress testing at a university hospital. Controlling for sociodemographic factors, health status, symptom severity, and history of prior procedures, women expressed greater willingness than men to accept a physician's recommendation of cardiac catheterization (odds ratio 7.1; 95% confidence interval 1.1, 45.3) and similar willingness to accept a recommendation for coronary angioplasty or coronary artery bypass graft surgery. We conclude that patient preferences are unlikely to explain gender disparities in the use of invasive cardiac procedures.