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Biomedical subjects

G Pandey

Publications and source records attributed to G Pandey.

At least 19 recordsLinked to original sources
PubMed2025

Alzheimer's subtypes A supervised, unsupervised, multimodal, multilayered embedded recursive (SUMMER) AI study.

Since Alzheimer's disease (AD) is a heterogeneous disease, different subtypes may have distinct biological, genetic, and clinical characteristics, requiring tailored interventions. While several proposed subtypes of AD exist, there is still no clear consensus on a definitive classification. By leveraging complementary AI approaches, including supervised and unsupervised learning, within a recursive pipeline (SUMMER) that integrates multimodal datasets encompassing MRI measurements, phenotypes, and genetic data, our goal was to generate robust scientific evidence for identifying AD subtypes. Data was downloaded from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database and included neuroimaging data (MRI), genetics (SNPs), clinical diagnosis, and demographics. 1133 European American participants' images, aged 55-95, were included in this study. The analysis was multi-fold, where the first step involved applying an unsupervised application to a subset of the MRI sample (AD + cognitively normal (CN) aged matched groups, 100 men aged 68-85 years, and 76 women aged 68-85 years). The MRI brain gray matter was segmented into 44 regions of interest (ROIs) according to a standard atlas, and 618 features were extracted, including ROI voxel intensity measurements such as minimum, maximum, and histogram variables. Results identified a cluster of subtype AD men and a cluster of subtype AD women that were distinct from the rest of their respective samples. In the next step, the integrity of the identified subtype AD clusters was investigated using the XGBoost supervised machine learning application with genetic features (SNPs, N=36,724) and labels: the identified subtype AD cluster vs. the rest of the sample, stratified by sex. A significant AD subtype men model (accuracy=0.85, F1=0.72, AUC=0.83) and a significant women AD subtype model (accuracy=0.81, F1=0.81, AUC=0.81) were built, confirming the homogeneity of the isolated AD subtype clusters. Discriminative biomarkers were extracted from the significant models, including selected ROIs and SNPs. Finally, the subtype models were tested on an unseen subset of ADNI data. The genetic-based models identified clusters of AD subtype participants consisting of 34% of the men AD group and 47% of the women AD group. Phenotypic analysis indicates that lower body weight was associated with the women's AD subtype. Complex diseases like AD demand a sophisticated, multimodal approach for precise diagnosis. Effectively identifying disease subtypes enhances the potential for personalized treatment, ultimately improving patient outcomes.

Journal Article↗
PubMed2003

Phytoremediation: an overview of metallic ion decontamination from soil.

In recent years, phytoremediation has emerged as a promising ecoremediation technology, particularly for soil and water cleanup of large volumes of contaminated sites. The exploitation of plants to remediate soils contaminated with trace elements could provide a cheap and sustainable technology for bioremediation. Many modern tools and analytical devices have provided insight into the selection and optimization of the remediation process by plant species. This review describes certain factors for the phytoremediation of metal ion decontamination and various aspects of plant metabolism during metallic decontamination. Metal-hyperaccumulating plants, desirable for heavily polluted environments, can be developed by the introduction of novel traits into high biomass plants in a transgenic approach, which is a promising strategy for the development of effective phytoremediation technology. The genetic manipulation of a phytoremediator plant needs a number of optimization processes, including mobilization of trace elements/metal ions, their uptake into the root, stem and other viable parts of the plant and their detoxification and allocation within the plant. This upcoming science is expanding as technology continues to offer new, low-cost remediation options.

Biodegradation, Environmental↗
PubMed2001

Two-stage cultivation of recombinant Saccharomyces cerevisiae to enhance plasmid stability under non-selective conditions: experimental study and modeling.

A leucine auxotroph strain of Saccharomyces cerevisiae was used to study plasmid stability and expression using a recombinant plasmid, which contained a foreign gene for firefly luciferase (luc). This recombinant yeast was tested in a series of continuous cultures in semi-defined media with varying concentrations of yeast extract in order to study its effect on stability. While the biomass concentration and luciferase activity increased with increasing concentrations of yeast extract, the plasmid stability declined. An analysis of the growth rates showed that the recombinants enjoyed a growth rate advantage over the plasmid-free cells at critically low yeast extract concentrations, possibly due to leucine starvation in the media. A two-stage cultivation strategy was designed in order to create a yeast extract limited environment so that plasmid-free cells could not grow and overtake the recombinant cells. The cells were cultivated in selective media in the first stage, and then transferred continuously to the second stage where the media was enriched by feeding yeast extract. The feed rate was kept low in order to ensure yeast extract and hence leucine starvation, thereby selecting against the plasmid-free cells. This strategy resulted in a stable existence of recombinant cells, which stabilized around 60% at steady state during the tested period of cultivation. The complex nitrogen feed helped in increasing the cell density and volumetric activity by approximately 9 and 18-fold respectively with respect to that achieved in minimal medium. The experimental data was used to formulate a mathematical model to predict cell growth and plasmid stability in two-stage cultivation, which correctly explained the experimental data.

Journal Article↗
PubMed2001

Colovesical fistula an unusual complication of cytotoxic therapy in a case of non-Hodgkin's lymphoma.

A 65-year old man, a known case of non-Hodgkin's lymphoma of base of the tongue and epiglottis presented with complaints of pneumaturia and faecaluria. He had received the first cycle of cytotoxic therapy (CHOP-regimen). At the end of the cycle he developed febrile neutropenia (circulating granulocyte count <1500/mm3). Cystogram showed air in the bladder area and a fistulous communication to a cavity behind the bladder. CT-scan showed air in the bladder, a fistulous communication between the sigmoid colon and bladder along with an intervening small abscess cavity. On exploration a fistulous communication between the sigmoid and bladder along with an intervening small abscess cavity was found. Resection of involved portion of sigmoid and end to end anastomosis along with a diverting colostomy was done. The bladder was closed in two layers with an omental interposition between it and the sigmoid along with a suprapubic cystostomy. The histopathology demonstrated only inflammatory response without any evidence of malignancy or diverticular disease.

Aged↗
PubMed2000

[3 + 2]-cycloaddition of nonstabilized azomethine ylides. 10. An efficient strategy for the construction of x-Azatricyclo[m.n.0. 0]

Various new structural entities related to x-azatricyclo[m.n.0. 0(a)()(,)(b)()]alkanes are constructed by the intramolecular [3 + 2] dipolar cycloaddition of nonstabilized cyclic azomethine ylides. The ylide is generated by the sequential double desilylation of N-alkyl alpha,alpha'-bis(trimethylsilyl)cyclic amines using Ag(I)F as a one-electron oxidant.

Journal Article↗
PubMed2000

PhSeSiR(3)-Catalyzed Group Transfer Radical Reactions.

A novel design for initiating radical-based chemistry in a catalytic fashion is described. The design of the concept is based on the phenylselenyl group transfer reaction from alkyl phenyl selenides by utilizing PhSeSiR(3) (1) as a catalytic reagent. The reaction is initiated by the homolytic cleavage of -C-Se- bond of an alkyl phenyl selenide by the in situ generated alkylsilyl radical (R(3)Si(*)), obtained by the mesolysis of PhSeSiR(3)](*)(-)( )()(1(*)(-)). The oxidative dimerization of counteranion PhSe(-) to PhSeSePh functions as radical terminator. The generation of 1(*)(-) is achieved by the photoinduced electron transfer (PET) promoted reductive activation of 1 through a photosystem comprising of a visible-light (410 nm)-absorbing electron rich DMA as an electron donor and ascorbic acid as a co-oxidant (Figure 1). The optimum mole ratio between the catalyst 1 and alkyl phenyl selenides for successful reaction is established to be 1:10. The generality of the concept is demonstrated by carrying out variety of radical reactions such as cyclization (10, 15-18), intermolecular addition (25), and tandem annulations (32).

Journal Article↗
PubMed2000

Decrease in reelin and glutamic acid decarboxylase67 (GAD67) expression in schizophrenia and bipolar disorder: a postmortem brain study.

BACKGROUND: Reelin (RELN) is a glycoprotein secreted preferentially by cortical gamma-aminobutyric acid-ergic (GABAergic) interneurons (layers I and II) that binds to integrin receptors located on dendritic spines of pyramidal neurons or on GABAergic interneurons of layers III through V expressing the disabled-1 gene product (DAB1), a cytosolic adaptor protein that mediates RELN action. To replicate earlier findings that RELN and glutamic acid decarboxylase (GAD)(67), but not DAB1 expression, are down-regulated in schizophrenic brains, and to verify whether other psychiatric disorders express similar deficits, we analyzed, blind, an entirely new cohort of 60 postmortem brains, including equal numbers of patients matched for schizophrenia, unipolar depression, and bipolar disorder with nonpsychiatric subjects. METHODS: Reelin, GAD(65), GAD(67), DAB1, and neuron-specific-enolase messenger RNAs (mRNAs) and respective proteins were measured with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) or Western blot analyses. Reelin-positive neurons were identified by immunohistochemistry using a monoclonal antibody. RESULTS: Prefrontal cortex and cerebellar expression of RELN mRNA, GAD(67) protein and mRNA, and prefrontal cortex RELN-positive cells was significantly decreased by 30% to 50% in patients with schizophrenia or bipolar disorder with psychosis, but not in those with unipolar depression without psychosis when compared with nonpsychiatric subjects. Group differences were absent for DAB1,GAD(65) and neuron-specific-enolase expression implying that RELN and GAD(67) down-regulations were unrelated to neuronal damage. Reelin and GAD(67) were also unrelated to postmortem intervals, dose, duration, or presence of antipsychotic medication. CONCLUSIONS: The selective down-regulation of RELN and GAD(67) in prefrontal cortex of patients with schizophrenia and bipolar disorder who have psychosis is consistent with the hypothesis that these parameters are vulnerability factors in psychosis; this plus the loss of the correlation between these 2 parameters that exists in nonpsychotic subjects support the hypothesis that these changes may be liability factors underlying psychosis.

Activating Transcription Factor 1↗
PubMed1999

Enhancing recombinant protein yields in Escherichia coli using the T7 system under the control of heat inducible lambda PL promoter.

A recombinant plasmid containing the complete lacZ gene downstream of the T7 promoter was used to transform Escherichia coli containing another plasmid which had the T7 RNA polymerase gene under the control of heat inducible lambda PL promoter. This recombinant E. coli containing the two plasmids was studied in order to enhance beta-galactosidase expression. The heat shock time which effectively regulates the T7 RNA polymerase was optimized and best expression of beta-galactosidase was obtained with 2 min heat shock. Substrate feeding increased the duration of log phase and allowed induction at a higher cell density without affecting the specific activity. A high cell density (7 g l-1) and high specific activity (approximately 20,000 U) were achieved which effectively increased the product concentration 18-fold.

Bacteriophage T7↗
PubMed1999

Glucocorticoids stimulate inflammatory 5-lipoxygenase gene expression and protein translocation in the brain.

In the brain, the expression of 5-lipoxygenase (5-LO), the enzyme responsible for the synthesis of inflammatory leukotrienes, increases during aging. Antiinflammatory drugs are currently being evaluated for the treatment of aging-associated neurodegenerative diseases such as Alzheimer's disease. Although generally considered antiinflammatory, glucocorticoids, whose production also increases during aging, are not particularly effective in this disease. In human monocytes, 5-LO mRNA content increases on exposure to the synthetic glucocorticoid dexamethasone, which prompted us to hypothesize that glucocorticoids might increase 5-LO expression in the brain as well. We treated rats for 10 days either with corticosterone (implanted subcutaneously) or with dexamethasone (injected daily); they were killed on day 10 after pellet implantation or 24 h after the 10th dexamethasone injection. We found increased levels of 5-LO mRNA and protein in hippocampus and cerebellum of glucocorticoid-treated rats; 5-LO-activating protein (FLAP) mRNA content was not affected. Using western immunobloting, we also observed the concurrent translocation of 5-LO protein from cytosol to membrane, an indication of its activation. Thus, glucocorticoid-mediated up-regulation of the neuronal 5-LO pathway may contribute to rendering an aging brain vulnerable to degeneration.

5-Lipoxygenase-Activating Proteins↗
PubMed1998

Verapamil for the treatment of acute mania: a double-blind, placebo-controlled trial.

OBJECTIVE: This study investigated the efficacy of verapamil in acute mania. METHOD: The study was a 3-week double-blind, random-assignment, parallel-group, placebo-controlled inpatient trial of verapamil for patients with acute mania. Of the 32 study patients, 15 were given placebo and 17 were given verapamil. RESULTS: Mean absolute change scores on the Mania Rating Scale at endpoint, with baseline scores as the covariates, did not differ between the verapamil and placebo groups. There were no significant differences between the two groups in age, sex, and presence of psychosis. CONCLUSIONS: The investigators found no benefit of verapamil over placebo in treating acute mania.

Acute Disease↗
PubMed1992

A longitudinal study of plasma cortisol and depressive symptomatology by random regression analysis.

The authors utilized a random regression model to test the longitudinal relationship between depressive symptomatology and plasma cortisol levels obtained before and after the administration of dexamethasone in 62 affectively ill inpatients. This statistical model for longitudinal studies permits the inclusion of subjects with incomplete data as well as subjects measured at different time points. The most significant relationships were found between decreases in depressive symptoms and decreases in the 8:30 AM predexamethasone and the 4:00 PM postdexamethasone cortisol values. Patients were also classified as responders or nonresponders, and the rate of change in several plasma cortisol measures were separately analyzed for these two groups. No differences in the rate of change in plasma cortisol levels were found between responders and nonresponders. These results suggest that the decreases in cortisol production associated with clinical improvement may be partially explained by a regression toward the mean effect. Some of the possible explanations for these results are discussed.

Adult↗
PubMed1992

Degree of asymmetry in lateral preferences: eye, foot, ear.

Lateral asymmetry in eye, foot, and ear preference was measured using a 15-item questionnaire administered to 442 subjects. Degree and magnitude of asymmetry were greatest for eye, followed by foot and ear. Intercorrelations of lateral preferences were all positive and significant. Two primary factors, eyedness and earedness, were established.

Adult↗
PubMed1988

Eating attitudes and glucose tolerance in anorexia nervosa patients at 8-year followup compared to control subjects.

This study analyzed eating attitudes and plasma glucose, insulin, unesterified fatty acid (FFA), human growth hormone (GH), and cortisol responses to an oral (100 g) glucose load in 26 female anorexia nervosa patients at an 8-year outcome evaluation in comparison to 14 age-matched female control subjects. Recovered patients who were of normal body weight and had cyclical menstruation (n = 19) showed glucose tolerance curves and insulin, cortisol, and GH responses that were indistinguishable from those of normal subjects, although patients tended to be more diet-conscious than controls and showed elevated fasting FFA levels. Two of 19 recovered patients met criteria for impaired glucose tolerance. Nonrecovered patients (n = 7) showed abnormal eating attitudes at an average underweight of 20% with persistent amenorrhea or oligomenorrhea. They had high fasting FFA plasma levels, significantly greater than normal rises in plasma glucose, a significant delay in serum insulin secretion, higher mean glucose levels before and after controlling for amount of exercise, and paradoxical release of GH. One of seven patients met criteria for diabetes mellitus and two of seven had impaired glucose tolerance. The findings suggest that fasting plasma FFA levels may reflect patients' eating and exercise habits more accurately than their verbal or written reports.

Adult↗
PubMed1986

4 p.m. baseline cortisol level as a predictor of DST results in depression.

To assess the relationship of baseline cortisol to the 1 mg dexamethasone suppression test (DST), 4 p.m. baseline and 4 p.m. postdexamethasone blood samples were drawn on 52 consecutive depressed outpatients. Baseline cortisol correlated significantly with post-DST values, and baseline levels above 15 micrograms/dl predicted DST nonsuppression with 90.4% accuracy. These data lend some support to the usefulness of baseline cortisol determination in depressed outpatients in whom a full DST may be difficult.

Ambulatory Care↗