Biomedical subjects
Publications and source records attributed to M Gupta.
Reinvestigation of the polar fractions from the stem bark of STEMMADENIA MINIMA A. Gentry (Apocynaceae) afforded two known and four new lignan glucosides. Their structures were deduced by spectroscopic and chemical methods.
Changes in myosin expression were studied after the removal of functional overload of skeletal and cardiac muscles. In the first set of experiments the chicken slow tonic anterior latissimus dorsi muscle was overloaded by placing a lead band over the wing. In the overloaded muscles the normal developmental progression toward elimination of slow myosin SM-1 was accelerated. No reexpression of SM-1 took place after weight removal. In the second set of experiments rat heart was overloaded by constriction of abdominal aorta. Isomyosin composition and the abundance of mRNA coding for alpha- and beta-myosin heavy chain (MHC) was determined. The overload resulted in downregulation of the alpha-MHC with corresponding upregulation of beta-MHC expression. Debanding resulted in the regression of hypertrophy and rapid return of alpha-MHC to normal values. In contrast, the recovery in beta-MHC expression was much slower and at 7 wk of debanding still remained substantially elevated.
The brain biochemistry in terms of certain key substances of brain were studied in 18% protein and 6% protein-fed rats following lead ingestion at a level of 1% in the diet. Lead ingestion diminished the protein and increased the RNA content of brain, and, consequently reduced the protein/RNA ratio. The RNA/DNA ratio in brain was elevated in lead toxicity, while the protein/DNA ratio remained unaltered. The RNase and DNase activities of brain were decreased. Lead treatment diminished the glutathione (GSH) level of blood but the GSH level of brain was not altered significantly by the lead treatment. The plasma protein level was also diminished after lead treatment. The effects of lead on some of these parameters were found to be more pronounced in rats receiving the 6% protein diet. The serotonin (5-HT) level of brain was reduced, while the norepinephrine (NE) and dopamine (DA) levels of brain were elevated following lead treatment. The monoamine oxidase (MAO) and tryptophan hydroxylase (TPH) activities and 5-hydroxy-indole acetic acid (5-HIAA) content of brain were elevated in lead-ingested rats. The effects of lead on these parameters were found to be potentiated when the rats were fed on a 6% protein diet. These studies suggest that lead at the present dose affects brain biochemistry in terms of both nucleic acids and amine metabolism, and protein deficiency potentiates some of these lead-induced changes.
Elastase of B. subtilis 6a caused lysis of freshly grown cells of Gram-negative (Proteus vulgaris, Klebsiella pneumoniae, Salmonella typhi and Pseudomonas aeruginosa and Gram-positive (B. subtilis) bacteria. Heat killed and lyophilised Gram-positive and negative bacteria showed higher sensitivity to elastase. Both Gram-negative and Gram-positive bacteria were lysed maximally by elastase at pH 8.0. At this pH, activity of elastase was maximum in Tris-HCl and glycine-NaOH buffers followed by Tris-maleate and cacodylate buffers.
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Antimicrobial activities of mycotoxin MT81 and its acetylated, benzoylated and acetic acid derivatives were determined by zone inhibition method. MT81, acetylated MT81 and acetic acid MT81 exhibited sensitivity (31.25, 62.50, 62.50 micrograms/ml respectively) to all the test bacteria. Benzoylated-MT81 did not exhibit any activity even up to 1000 mcg/ml. MT81, its acetylated and acetic acid derivatives exhibited antifungal activity up to 62.5 micrograms/ml and 125.0 micrograms/ml respectively against test yeasts and other fungi. Benzoylated MT81 also exhibited antifungal activity but the degree was comparatively less.
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Egr-1 is an early growth response gene that encodes a protein with three zinc fingers and is involved in transcriptional regulation. In adult heart myocytes, in contrast to c-fos and c-myc, high levels of Egr-1 mRNA expression have been shown. Here we report that Egr-1 transactivates rat cardiac alpha-MHC gene expression. In serum-starved primary cultures of 18-day-old fetal rat heart myocytes, addition of serum evoked expression of both Egr-1 and alpha-MHC gene transcripts. Inclusion of 10 microM cycloheximide in these cultures for 48 h caused a greater increase in Egr-1 mRNA, whereas the expression of alpha-MHC transcripts was ablated. To examine the involvement of Egr-1 in alpha-MHC induction, we transfected primary cultures of cardiac myocytes with plasmids pCMVEgr-1 (Egr-1 expression vector) and pMP3.3CAT containing -2.9- to +0.42-kilobase sequences of the alpha-MHC gene fused to the coding region of the chloramphenicol acetyltransferase (CAT) gene. Cotransfection of pCMVEgr-1 stimulated expression of pMP3.3CAT 10-15-fold. Furthermore, pCMVEgr-1 also stimulated expression of the endogenous alpha-MHC gene in primary cultures of cardiac myocytes. Transactivation of pMP3.3CAT expression by pCMVEgr-1 was also observed by transfecting the myogenic cell line Sol 8, but not in L6E9 cells or in NIH3T3 fibroblasts. By creating progressive 5' deletions of the alpha-MHC gene, we found that the region extending between -1698 and -1283 base pairs is necessary for Egr-1-induced expression of the alpha-MHC/CAT construct. These results define a physiological target for the Egr-1 transcription factor and delineate a novel mechanism for regulation of the alpha-MHC gene.
The effect of cAMP on cardiac myosin heavy chain (MHC) gene expression in primary cultures of 18-day-old fetal rat heart myocytes was investigated. When myocytes were treated with either 10 microM forskolin or 1 mM 8-bromo-cAMP for 48 h, the relative amount of the V1 to -V3 myosin isoform ratio increased 3-fold. The abundance of alpha-MHC mRNA was also increased 3-to-4-fold in forskolin treated vs control cells. However, no appreciable change was observed in the level of beta-MHC mRNA. In addition, a 70% increase in the transcription rate of the cardiac MHC gene was observed by nuclear run-on assay following treatment of cells with 10 microM forskolin for 12 h. These results demonstrate the preferential induction of alpha-MHC mRNA by cAMP which is, in part, mediated by transcriptional activation of the gene.
The cardiac phenotype exhibits considerable plasticity, being under the regulation of numerous factors, such as developmental stage, functional load, as well as nutritional and hormonal states of the animal. Several lines of evidence indicate that the adrenergic nervous system plays an important role in the redistribution of myosin isoforms in the heart. For example, chemical sympathectomy favors the expression of V3 isomyosin at the expense of V1. In this study, we have examined the effect of adrenergic pathways on the expression of cardiac myosin heavy chain (MHC) genes. The level of cAMP was modulated by either adding forskolin or 8-bromo-cAMP to primary cultures of embryonic (18 d) cardiac myocytes. We have found that the level of mRNA coding for MHC-alpha was increased two- to three-fold. The effect was dose- and time-dependent and was potentiated further when the 8-Br-cAMP was given together with a phosphodiesterase inhibitor. The same changes were found in KCl arrested cells, indicating independence of contractile activity. Treatment of cells known to activate the protein kinase C (TPA) and inositol triphosphate pathways has increased the level of beta-MHC mRNA while that of alpha-MHC remained unchanged. These data lend strong support to direct effect of the adrenergic system on activity of cardiac genes.
The 139 kb circular maize chloroplast genome was cloned in a linear form in a single yeast artificial chromosome (YAC), and several such clones were then analyzed to study the stability of large DNA sequences in YACs. The YAC clones were isolated from a partial maize DNA YAC library. The library was constructed by Bal-31 nuclease digestion of high-molecular-weight total maize genomic DNA followed by blunt-end ligation into a modified YAC vector, pYAC11. All chloroplast genome-containing YACs (cpYACs) were characterized by comparing their restriction enzyme digestion patterns with that of purified maize chloroplast DNA (MCD). Comparison of the restriction patterns of four cpYACs, MY503, MY504, MY518 and MY526, with that of MCD did not show any change in the size of the restriction fragments except at the chloroplast DNA-vector junction fragments. These altered size fragments were confirmed as junction fragments by hybridization of the pYAC11 border fragments. The end-specific T3 and T7 transcripts synthesized from MY503 also identified the same junction fragments as did the pYAC11 border fragments. Most cpYACs were completely stable through the analyzed one hundred generations.
We have isolated and characterized five overlapping clones that encompass 3.2 kb and encode a part of the short subfragment 2, the hinge, and the light meromyosin regions of the myosin heavy chain rod as well as 143 bp of the 3' untranslated portion of the mRNA. Northern blot analysis showed expression of this mRNA mainly in ventricular muscle of the adult chicken heart, with trace levels detected in the atrium. Transient expression was seen in skeletal muscle during development and in regenerating skeletal muscle following freeze injury. To our knowledge, this is the first report of an avian ventricular myosin heavy chain sequence. Phylogenetic analysis indicated that this isoform is a distant homolog of other ventricular and skeletal muscle myosin heavy chains and represents a distinct member of the multigene family of sarcomeric myosin heavy chains. The ventricular myosin heavy chain of the chicken is either paralogous to its counterpart in other vertebrates or has diverged at a significantly higher rate.
The present experiments were performed to determine whether the age-related loss of striatal D2 receptors could be localized to a kainic acid-sensitive neuronal population. This neurotoxin selectively destroys intrinsic neurons. Thus, if kainic acid reduced striatal D2 receptor concentrations such that age differences in this parameter were no longer observed, it would be a good indication that the D2 receptors lost through aging are also sensitive to kainic acid. Mature (6 months) and senescent (24 months) rats were stereotaxically, unilaterally injected with 3 micrograms/0.5 microliter kainic acid into the right striatum. Seven days later striatal D2 receptors were assessed with [3H]-spiperone in one group of mature and senescent rats. A second group of mature and senescent unilaterally lesioned rats was anesthetized and perfused. Brains were dissected and processed for striatal cell counts using cresyl violet staining, tyrosine hydroxylase and met-enkephalin using immunocytochemistry, and acetylcholinesterase using histochemistry. Age-related differences in D2-receptor concentrations were observed in intact, but not lesioned, striata. Kainic acid was less effective in reducing D2-receptor concentrations in senescent animals, suggesting that some proportion of the receptors was already lost prior to lesioning. Kainic acid also reduced total neuronal numbers, as well as Met-Enk and AChE positive staining, to approximately the same extent in mature and senescent rats. No age differences were seen in any of the other parameters following kainic acid administration.
The uptake of cadmium by cultured vegetative clones of the aquatic fern Marsilea minuta was studied in a static experimental bioassay system as functions of dose and period of exposure. The pathomorphological manifestations of Cd toxicity, as studied by transmission electron microscope, indicated damage to chloroplasts and tonoplasts as well as electron opaque granular deposits. Preliminary evidence based on molecular sieving chromatography showed the formation of two cadmium-binding proteins of 78 and 33 kDa in the leaf tissue under cadmium stress.
Disseminated histoplasmosis is one of the life-threatening opportunistic infections associated with acquired immune deficiency syndrome (AIDS). A 29-year-old man with AIDS and disseminated histoplasmosis complained of a hazy spot in the vision of his left eye. Results of examination showed distinct creamy white intraretinal and subretinal infiltrates in both eyes. The patient died within a month from pulmonary infection with Histoplasma capsulatum and cytomegalovirus. Examination with light microscopy showed that the right and left eyes contained histoplasma yeast cells in lesions of retinitis, optic neuritis, and uveitis. These lesions contained variable numbers of lymphocytes and histiocytes. Electron microscopy of the histoplasma in tissue showed characteristic features. This case illustrates the funduscopic appearance and histopathology of histoplasmic retinitis, an uncommon although important ophthalmologic complication of AIDS.
A retrospective study of 36 confirmed cases of subacute sclerosing panencephalitis (SSPE) was carried out to detect any variation in the clinical and EEG patterns previously described. There were 31 males and 5 females, aged 4 to 24 years. Onset of SSPE at or after 15 years of age was observed in 22.2% of cases. Rapid progression of the disease was observed in 52%. The first symptom was myoclonus in 61.6%, mental regression in 22.2% and generalised seizures in 11.1% of cases. Low positive measles antibody titres in the CSF were found in 36.1% of cases. EEG analysis revealed slow background in 69.2% and periodic complexes in 94.4% of cases. Atypical periodic complexes, focal abnormalities and paroxysms of bisynchronus sharp activity were also observed.
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