An improved model averaging scheme for logistic regression

Recently, penalized regression methods have attracted much attention in the statistical literature. In this article, we argue that such methods can be improved for the purposes of prediction by utilizing model averaging ideas. We propose a new algorithm that combines penalized regression with model averaging for improved prediction. We also discuss the issue of model selection versus model averaging and propose a diagnostic based on the notion of generalized degrees of freedom. The proposed methods are studied using both simulated and real data.

Successful management in neglected cases of adult anorectal malformation

Posterior sagittal anorectoplasty (PSARP) is the procedure of choice in cases of anorectal malformation in children. Adult patients can present with anorectal malformation in developing countries. As there is very little data regarding the success of PSARP in cases of adult anorectal malformations, the aim of this study was to perform and assess the effectiveness of PSARP in adults. Two adults (one male, one female) aged 16 and 17 years, respectively, underwent a diverting colostomy followed by a PSARP. The female underwent a posterior vaginal anorectoplasty due to a rectovaginal fistula and is leading a normal life. The male patient had a rectourethral fistula which required meticulous dissection and is now doing well with a Kelly's score of five. Our experience here suggests that a PSARP provided satisfactory results in adults who present late with an anorectal malformation.

A systems biology approach towards understanding the process of blastocyst implantation

Time-synchronous development of endometrium and embryo under adequate progesterone dominance is considered integral to the process of blastocyst implantation in the human. It now appears that hypothesis-driven and candidate-based deductive approach fails to explain this complex control process. We propose a systems biology approach to elucidate the control process underlying the physiological basis of successful interfacing between embryo and endometrium towards blastocyst implantation. Elucidation of the time course pattern of transcriptomics involved in the process of blastocyst implantation in mid-luteal phase endometrium with and without progesterone dominance, as well as, with and without viable embryo shall elaborate upon the polygenic and multifactorial nature of the process of blastocyst implantation. Accordingly, a large scale homeodynamic model of hierarchical arrangement of functional networks of regulatory genomic expressional elements at the level of endometrial receptivity shall emerge. It is anticipated that such a systems biology approach shall provide an integrated picture of the process and shall also open up novel areas of basic, strategic and translational research in the biology of blastocyst implantation.

A comparative study of different graft materials used in myringoplasty

Two hundred twenty cases of unilateral chronic suppurative otitis media (CSOM) with dry central perforation were chosen for this study and myringoplasty were done. Age group ranged from 13 to 48 years. Four types of autogenous tissues were used as graft material. Grafting was done by underlay technique when temporalis fascia, tragal perichondrium, areolar tissue were used as graft material and when fat graft was used the ear lobule fat was placed directly into perforation through transcanal route. Postoperative follow-up was carried out up to 6 months. In this study, it was found that the younger age group has less impairment of hearing and better chance of tympanic membrane perforation closure than the older age group in CSOM with central perforation. Anterior perforations has less impairment of hearing and better result in successful closure of tympanic membrane than posterior perforation group. It was also observed that larger the size of perforation greater is the hearing impairment preoperatively and postoperative hearing gain is also less compared to small perforation. Best hearing improvement occurred using temporalis fascia. Failure occurred may be due to postoperative infection, respiratory tract infection, neglected post-operative advice etc.

Effect of low-dose mifepristone administration on day 2 after ovulation on transcript profiles in implantation-stage endometrium of rhesus monkeys

Progesterone is essential for endometrial receptivity in primates. In studies previously performed using global gene profiling based on microarray technology, attempts have been made to identify changes in gene expression between early luteal-phase and mid-luteal-phase endometria. However, the issue of the putative impact of preimplantation embryo-derived signal in the process of endometrial receptivity was missing in the previous studies. In the present study, an attempt has been made to delineate the transcripts profile in implantation-stage endometrium under combinatorial regulation of progesterone and embryo-derived signal in the rhesus monkey. To this effect, we have compared transcript profiles for 409 known genes between control receptive stage (n=13), and mifepristone-induced desynchronized and non-receptive stage (n=12) monkey endometrial samples collected on days 4 (n=12) and 6 (n=13) after ovulation from mated, potential conception cycles, using cDNA arrays containing sequence-verified clones. Statistical analysis of correlation of estimated transcript abundance between arrays and qRT-PCR for nine selected gene products yielded significant (P<0.05) concordance. Of 409 genes, a total of 40 gene transcripts were seen to be affected, nine gene transcripts in endometrial samples were found to progressively increase between days 4 and 6 following mifepristone treatment, while an additional five genes showed differential expression profile depending on the day after treatment. Additionally, different sets of 12 and 14 gene products showed changes in days 4 and 6 post-ovulation samples respectively. A new cohort of 28 gene products in implantation-stage endometrium was seen to be affected by luteal-phase mifepristone.

Fasting total homocysteine (tHcy) concentration and mortality in older Mexican Americans

OBJECTIVES

This study examines the association between tHcy on cardiovascular and noncardiovascular mortality.

DESIGN

Longitudinal study of 1,633 Mexican Americans age>60 years recruited in 1998.

SETTING

Sacramento, California.

MEASUREMENTS

Cox proportional models were used to estimate the effects of tHcy on mortality rate in the total sample and in a subgroup of subjects without a history of cardiovascular disease at baseline.

RESULTS

About half of the cohort was born in Mexico. Among Mexican-born participants, high tHcy (>11.0 micromol/L) was associated with a higher rate of cardiovascular mortality compared to those with low tHcy concentration

CONCLUSIONS

The effect of tHcy on cardiovascular mortality is nearly 40% stronger among the immigrant group. tHcy might be an early marker of subclinical vascular pathology amongst the Mexican-born group, despite their apparently healthy profile at baseline.

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Key Words

• homocysteine
• cardiovascular mortality
• mexican americans
• nutritional biomarkers
• elderly

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MESH Headings

• Aged
• Aged, 80 and over
• Biomarkers/blood
• California/epidemiology
• Cardiovascular Diseases/ethnology
• Cardiovascular Diseases/mortality
• Female
• Homocysteine/blood
• Humans
• Longitudinal Studies
• Male
• Mexican Americans
• Mexico/ethnology
• Middle Aged
• Proportional Hazards Models

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Grants

• 1R24HD047861 NICHD NIH HHS
• P60 DK20572 NIDDK NIH HHS
• R01 DK060753 NIDDK NIH HHS
• AG12975 NIA NIH HHS
• R24 HD047861 NICHD NIH HHS
• DK60753 NIDDK NIH HHS
• R01 DK060753-03 NIDDK NIH HHS
• R03 AG033751 NIA NIH HHS
• R01 AG012975 NIA NIH HHS
• P60 DK020572-30 NIDDK NIH HHS
• P30 DK092926 NIDDK NIH HHS
• R01 AG012975-11 NIA NIH HHS
• P60 DK020572 NIDDK NIH HHS
• RWJ04823 PHS HHS

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Treatment of fluoride containing drinking water by electrocoagulation using monopolar and bipolar electrode connections

Electrocoagulation was investigated for the effective removal of fluoride from drinking water. Different initial concentrations (2-10 mg L(-1)) of fluoride were considered for the experiment. Two different electrode connections (monopolar and bipolar) were examined for choosing the better alternative in order to intensify the performance of the process. It was observed that the removal of fluoride was better for bipolar connection than for monopolar connection. The final recommendable limit of fluoride (1 mg L(-1)) was obtained in 30 min at 625 Am(-2) using bipolar connection. The corrosion of electrodes as well as the sludge formed during the process was estimated for the bipolar connection. Thickness of film generated on the electrode surfaces in bipolar connection was also estimated at different current densities as well as for different initial fluoride concentrations. By-products obtained from the electrocoagulation bath were analyzed using SEM, EDAX, FTIR and XRD and explained. Comparative cost estimation for both electrode connections was adopted and presented as well. Total operating costs for monopolar and bipolar connections were 0.38 and 0.62 US$ m(-3), respectively, for the initial fluoride concentration of 10 mg L(-1). These findings might be useful in order to treat the fluoride contaminated water for drinking.

Removal of Fe(II) from tap water by electrocoagulation technique

Electrocoagulation (EC) is a promising electrochemical technique for water treatment. In this work electrocoagulation (with aluminum as electrodes) was studied for iron Fe(II) removal from aqueous medium. Different concentration of Fe(II) solution in tap water was considered for the experiment. During EC process, various amorphous aluminum hydroxides complexes with high sorption capacity were formed. The removal of Fe(II) was consisted of two principal steps; (a) oxidation of Fe(II) to Fe(III) and (b) subsequent removal of Fe(III) by the freshly formed aluminum hydroxides complexes by adsorption/surface complexation followed by precipitation. Experiments were carried out with different current densities ranging from 0.01 to 0.04 A/m2. It was observed that the removal of Fe(II) increases with current densities. Inter electrode distance was varied from 0.005 to 0.02 m and was found that least inter electrode distance is suitable in order to achieve higher Fe(II) removal. Other parameters such as conductivity, pH and salt concentration were kept constant as per tap water quality. Satisfactory iron removal of around 99.2% was obtained at the end of 35 min of operation from the initial concentration of 25 mg/L Fe(II). Iron concentration in the solution was determined using Atomic absorption spectrophotometer. By products obtained from the electrocoagulation bath were analyzed by SEM image and corresponding elemental analysis (EDAX). Cost estimation for the electrocoagulation was adopted and explained well. Up to 15 mg/L of initial Fe(II) concentration, the optimum total cost was 6.05 US$/m3. The EC process for removing Fe(II) from tap water is expected to be adaptable for household use.

Molecular mechanism of manganese exposure-induced dopaminergic toxicity

Manganese (Mn) is an essential mineral that is found in varying amounts in aerosols or dust. Exposure to atmospheric Mn at high concentration is a risk factor in humans that can manifest as neuronal degeneration resembling Parkinson's disease (PD). Since the underlying mechanism of Mn and dopamine (DA) interaction-induced cell death remains unclear, here, we showed that Mn exposure alone to mesencephalic cells for 24h induced minimal apoptotic cell death. However, cells pre-exposed to DA for 2h accelerated Mn-induced apoptosis. The vulnerability of Mn-induced apoptotic cell death to DA was determined by measuring lactate dehydrogenase (LDH) and Apoptag TUNEL staining (terminaldeoxynucleotidyl transferase DNA labeling). This was further confirmed by the cell viability assay to support our hypothesis that DA at the cellular level interacts with Mn and causes cells to be more susceptible. Pretreatment with nitric oxide blocker (7-nitroindazole, 7-NI), vitamin E or NF-kappaB inhibitor (SN50) significantly protected the cells from Mn and DA interaction-induced reactive oxygen species (ROS) and apoptosis. Western blot analysis showed that Mn in the presence of DA markedly induced induction of NOS (iNOS) expression. Pretreatment with 7-NI, SN50 or vitamin E significantly attenuated increased iNOS expression indicating that iNOS expression is regulated by ROS and the transcription factor NF-kappaB. Further, the generation of ROS as an early event in Mn and DA interaction is not controlled by NF-kappaB as SN50 pretreatment did not prevent ROS. These findings suggest that NF-kappaB induction and the activation of nitric oxide synthase through ROS represent a proximate mechanism for Mn-induced neurotoxicity.

Role of virulence plasmid of Aeromonas hydrophila in the pathogenesis of ulcerative disease syndrome in Clarias batrachus

Pathogenic Aeromonas hydrophila (strain VB21), a multiple-drug resistance strain contains a plasmid of about 21 kb. After curing of plasmid, the isolates became sensitive to antimicrobials, to which they were earlier resistant. The cured bacteria exhibited significant alterations in their surface structure, growth profile and virulence properties, and failed to cause ulcerative disease syndrome (UDS) when injected into the Indian catfish Clarias batrachus. Routine biochemical studies revealed that the plasmid curing did not alter the biochemical properties of the bacteria. After transformation of the plasmid into cured A. hydrophila the bacterium regained its virulence properties and induced all the characteristic symptoms of UDS when injected into fish. Thus, the plasmid plays a pivotal role in the phenotype, growth and virulence of A. hydrophila and pathogenesis of aeromonad UDS.

Human sulfatases: a structural perspective to catalysis

The sulfatase family of enzymes catalyzes hydrolysis of sulfate ester bonds of a wide variety of substrates. Seventeen genes have been identified in this class of sulfatases, many of which are associated with genetic disorders leading to reduction or loss of function of the corresponding enzymes. Amino acid sequence homology suggests that the enzymes have similar overall folds, mechanisms of action, and bivalent metal ion-binding sites. A catalytic cysteine residue, strictly conserved in prokaryotic and eukaryotic sulfatases, is post-translationally modified into a formylglycine. Hydroxylation of the formylglycine residue by a water molecule forming the activated hydroxylformylglycine (a formylglycine hydrate or a gem-diol) is a necessary step for the enzyme's sulfatase activity. Crystal structures of three human sulfatases, arylsulfatases A and B(ARSA and ARSB), and estrone/dehydroepiandrosterone sulfatase or steroid sulfatase (STS), also known as arylsulfatase C, have been determined. While ARSA and ARSB are water-soluble enzymes, STS has a hydrophobic domain and is an integral membrane protein of the endoplasmic reticulum. In this article, we compare and contrast sulfatase structures and revisit the proposed catalytic mechanism in light of available structural and functional data. Examination of the STS active site reveals substrate-specific interactions previously identified as the estrogen-recognition motif. Because of the proximity of the catalytic cleft of STS to the membrane surface, the lipid bilayer has a critical role in the constitution of the active site, unlike other sulfatases.

Immunoneutralization of vascular endothelial growth factor inhibits pregnancy establishment in the rhesus monkey (Macaca mulatta)

Maternal endometrial vascular endothelial growth factor (VEGF) is considered important in blastocyst implantation. However, there is no direct evidence to support this conjecture in the primate. In the present study, we have examined this hypothesis by testing whether immunoneutralization of VEGF during the peri-implantation stage of gestation affects embryo implantation in the rhesus monkey. Adult female animals (n = 36) during mated ovulatory cycles were randomly assigned to one of the experimental groups treated subcutaneously with either isotype-matched mouse immunoglobulin (group 1: control, n = 8) or monoclonal mouse antibody against VEGF-A (anti-VEGF Mab; group 2: 10 mg on day 5 after ovulation, n = 8; group 3: 20 mg on day 5 after ovulation, n = 8; group 4: 10 mg on day 10 after ovulation, n = 4; group 5: 10 mg on days 5 and 10 after ovulation, n = 8). Anti-VEGF Mab-treated animals in groups 2–4 did not show any marked inhibition in pregnancy establishment. On pooled analysis, however, anti-VEGF Mab administration in groups 2–5 (n = 28) resulted in a significant (P < 0.04) decline in the number of viable term pregnancy when compared with control animals. The observed difference was explained by the fact that 10 mg anti-VEGF Mab given to each animal on days 5 and 10 after ovulation in group 5 (n = 8) inhibited pregnancy establishment significantly (P < 0.02) when compared with control group 1. There was no significant change in serum concentrations of estradiol-17β, progesterone, and free VEGF among groups. Furthermore, animals treated with anti-VEGF Mab (n = 8) as in group 5 revealed marked decrease in immunoreactive VEGF, fms-like tyrosine kinase-1, and kinase-insert domain region in trophoblast cells associated with shallow uterine invasion on day 13 of gestation when compared with samples from control group animals (n = 8). Thus, VEGF action is required for successful blastocyst implantation in the rhesus monkey.

Biocompatibility of diamond-like nanocomposite thin films

Diamond-like nanocomposite (DLN) films consist of network structure of amorphous carbon and quartz like silicon. In the present work, DLN films have been synthesized on pyrex glass and subsequently, their biocompatibility have been investigated through primary and secondary cell adhesion, cytotoxicity, protein adsorption and murine peritoneal macrophage activation experiments. Variable degree of cell and protein response have been found based on variable film synthesis parameters but in overall, required biocompatibility has been established for all types of film-coating.

Pharmacogenomics and nutrigenomics: synergies and differences

The success of the Human Genome Project and the spectacular development of broad genomics tools have catalyzed a new era in both medicine and nutrition. The terms pharmacogenomics and nutrigenomics are relatively new. Both have grown out of their genetic forbears as large-scale genomics technologies have been developed in the last decade. The aim of both disciplines is to individualize or personalize medicine and food and nutrition, and ultimately health, by tailoring the drug or the food to the individual genotype. This review article provides an overview of synergies and differences between these two potentially powerful science areas. Individual genetic variation is the common factor on which both pharmacogenomics and nutrigenomics are based. Each human is genetically (including epigenetics) unique and phenotypically distinct. One of the expectations of both technologies is that a wide range of gene variants and related single-nucleotide polymorphism will be identified as to their importance in health status, validated and incorporated into genotype based strategies for the optimization of health and the prevention of disease. Pharmacogenomics requires rigorous genomic testing that will be regulated and analyzed by professionals and acted on by medical practitioners. As further information is obtained on the importance of the interaction of food and the human genotype in disease prevention and health, pharmacogenomics can provide an opportunity driver for nutrigenomics. As we move from disease treatment to disease prevention, the two disciplines will become more closely aligned.