Biomedical subjects
S De
Publications and source records attributed to S De.
Phosphatidylcholine activation of human heart (R)-3-hydroxybutyrate dehydrogenase mutants lacking active center sulfhydryls: site-directed mutagenesis of a new recombinant fusion protein.
(R)-3-Hydroxybutyrate dehydrogenase (BDH) is a lipid-requiring mitochondrial enzyme with a specific requirement of phosphatidylcholine (PC) for function. A plasmid has been constructed to express human heart (HH) BDH in Escherichia coli as a hexahistidine-tagged fusion protein (HH-Histag-BDH). A rapid two-step affinity purification yields active HH-Histag-BDH (and six mutants) with high specific activity ( approximately 130 micromol of NAD(+) reduced.min(-1).mg(-1)). HH-Histag-BDH has no activity in the absence of phospholipid and exhibits a specific requirement of PC for function. The HH-Histag-BDH-PC complex (and HH-BDH derived therefrom by enterokinase cleavage) has apparent Michaelis constants (K(m) values) for NAD(+), NADH, (R)-3-hydroxybutyrate (HOB), and acetoacetate (AcAc) similar to those for bovine heart or rat liver BDH. A computed structural model of HH-BDH predicts the two active center sulfhydryls to be C69 (near the adenosine moiety of NAD) and C242. With both sulfhydryls derivatized, BDH has minimal activity, but site-directed mutagenesis of C69 and/or C242 now shows that neither of these cysteines is required for PC activation or catalysis (the double mutant, C69A/C242A, is highly active with essentially normal kinetic parameters). Six cysteine mutants each have an increased K(m)(NADH) (2-6-fold) but an unchanged K(m)(NAD)+. The C242S and C69A/C242S enzymes (but not the analogous C242A mutants nor the C69A or C69S mutants) exhibit approximately 10-fold increases in K(m)(HOB) and K(m)(AcAc), reflecting an altered substrate binding site. Thus, although C242 (in the C-terminal lipid binding domain of BDH) is close to the active site, it appears to be in a hydrophobic environment and only indirectly defines the substrate binding site at the catalytic center of BDH.
Chemopreventive activity of quercetin during carcinogenesis in cervix uteri in mice.
The chemopreventive action of quercetin was examined during 20-methyl cholanthrene induced cervical neoplasia in virgin Swiss albino mice. The effects were evaluated on the basis of histopathological observation of the cervical epithelium, micronucleus frequency in vaginal exfoliated cells and some biochemical parameters in the host liver. Quercetin was found to arrest or reverse the progression of cervical neoplasia. The micronucleus frequency was reduced following its administration. The potential anti-carcinogenic effect of quercetin noted in this study is attributed to its antioxidant property which was reflected in the lipid peroxides and their role in the host detoxification system, as expressed in liver glutathione level, glutathione-S-transferase, glutathione peroxidase, catalase and superoxide dismutase activity. As an integral part of the diet quercetin may offer protection to the epithelium from the damaging effects of carcinogenic chemicals.
PCR detection of Giardia lamblia in stool: targeting intergenic spacer region of multicopy rRNA gene.
A PCR based detection that amplifies the 552-bp intergenic spacer (IGS) region of multicopy rRNA gene of Giardia lamblia and 320-bp internal sequences to first PCR product has been used in diagnosis of giardiasis in stool sample. The primers were found highly specific to Giardia spp. only, because no amplification was observed with DNAs from other enteric pathogens like Escherichia coli, Shigella dysenteriae and Entamoeba histolytica. The test could detect even less than 2 pg of genomic DNA from Giardia trophozoites. In direct diagnosis of Giardia lamblia in stool samples, it was observed that PCR amplification of IGS followed by nested PCR could enhance the sensitivity and specificity of the tests manifold and the system was able to detect as low as 10 parasites in 100 microl of stool. The comparative evaluation of the present system with conventional microscopy, CIEP and ELISA in the diagnosis of giardiasis from diarrhoeic stool samples and control subjects demonstrated a 100% correlation among nested PCR, microscopic examination and ELISA in patients suggestive of giardiasis (Group I) and control subjects (Group II). In Group I cases (patients suffering from other than giardiasis), CIEP, ELISA and nested PCR showed better results than microscopic examination. However, among them, PCR was found most sensitive and specific because 20% positivity was noticed by PCR whereas CIEP and ELISA showed only 7.14% and 12.85%, respectively. Break-up results showed that all the samples which were positive by CIEP or ELISA, also found positive by PCR. The present observation clearly suggests the use of PCR that amplifies the intergenic spacer region of multicopy rRNA gene of Giardia lamblia followed by nested PCR for routine, quick and reliable detection of Giardia lamblia in stool samples.
An isoflavone from Myristica malabarica.
Phytochemical investigation of the heartwood of Myristica malabarica has led to the isolation of the new 7,4'-dimethoxy-5-hydroxyisoflavone together with two other isoflavones, biochanin A and prunetin, and a 1,3-diarylpropanol and a rare alpha-hydroxydihydrochalcone.
Prevention of carcinogen-induced mouse skin papilloma by whole fruit aqueous extract of Momordica charantia.
The anticarcinogenic effect of aqueous extract of fruit of Momordica charantia (bitter gourd), which is widely used as a vegetable in India, was studied in a two-step skin carcinogenesis model in mice. The possible mode of action was also investigated. Oral administration of the fruit extract was found to have an adverse effect on the general health and lifespan of the animals when used at a high concentration. But when this dose was reduced by half, the test extract afforded protection from the development of skin tumour and increased life expectancy. Carcinogen-induced lipid peroxidation in liver and DNA damage in lymphocytes were found to be reduced following treatment with Momordica. The fruit extract was found to significantly activate the liver enzymes glutathione-S-transferase, glutathione peroxidase and catalase (P < 0.001), which showed a depression following exposure to the carcinogen. The results suggest a preventive role of water-soluble constituents of M. charantia fruit during carcinogenesis, which is mediated possibly by their modulatory effect on enzymes of the biotransformation and detoxification system of the host.
An extreme and unusual variant of Ramsay Hunt syndrome.
Ramsay Hunt syndrome is characterized by facial nerve paralysis, herpetic vesicles in or around the ear and pain often associated with vestibulocochlear nerve involvement. It is thought to be a cranial polyneuropathy caused by the herpes zoster virus. We present an extreme and unusual variant of this disease with involvement of VIIth, VIIIth, Xth, XIth and XIIth cranial nerves as well as C2-4 sensory dermatomes and profound systemic upset which caused some diagnostic uncertainty.
Immune response of children who develop persistent diarrhea following rotavirus infection.
A prospective study was conducted with Bangladeshi children with rotavirus (RV) diarrhea to assess whether nutritional and clinical parameters, RV serotypes, levels of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-alpha), and gamma interferon (IFN-gamma), and RV-specific antibody titers in plasma and stool were associated with the development of persistent diarrhea. Children with watery diarrhea for 6 to 8 days, selected from the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), were enrolled in the study and monitored until diarrhea improved. Children were classified as having acute diarrhea (AD) if diarrhea resolved within 14 days of onset and as having persistent diarrhea (PD) if diarrhea persisted for more than 14 days after onset. Uninfected, control children (n = 13) from the Nutrition Follow-Up Unit of ICDDR,B were also enrolled. Of the 149 children with diarrhea enrolled, 29 had diarrhea with RV alone, of which 19 had AD and 10 developed PD. Samples of stool and blood were collected from all children on enrollment. Stool samples were collected again from children when they developed PD. Of the 10 children who had an initial RV infection and then developed PD, only one had persistent RV infection. Plasma levels of IL-10 and TNF-alpha were higher in children with diarrhea compared to uninfected controls but were similar in children with AD and PD. Plasma IFN-gamma levels were higher in children who developed PD than in those with AD (P = 0.008) or uninfected controls (P = 0.001). In stools, the levels of TNF-alpha, the only cytokine detected, were similar in the three groups of children. RV-specific immunoglobulin G (IgG) titers in plasma were higher in uninfected children than in those with AD (P < 0.001) or PD (P = 0.024) but titers were similar in children with AD and PD. RV-specific IgA titers in plasma and stool were similar in the three groups of children. From all observed parameters, only elevated plasma IFN-gamma levels were associated with subsequent development of PD. However, a larger sample size is necessary to substantiate this observation.
Thin walled models for haptic and graphical rendering of soft tissues in surgical simulations.
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Klippel-Trenaunnay-Weber syndrome.
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Calculation of van't Hoff enthalpy associated with aspirin-induced change in liposomal membrane anisotropy.
The lipid disordering effect of aspirin on the liposomal membrane of dipalmitoyl phosphatidyl choline has recently been studied using the fluorescence polarization method. From the anisotropy-temperature curve, we have calculated here the associated change in van't Hoff enthalpy. Since the fluorescence technique requires a very small amount of sample (10(-4) M), this method of enthalpy calculation compares well and is advantageous over the standard calorimetric methods.
Role of phospholipase C and tyrosine kinase systems in growth response of human airway smooth muscle cells.
The primary culture of confluent human airway smooth muscle (ASM) cells were exposed up to 5 days to human recombinant interleukin (IL)-1 beta in the presence of indomethacin and 1% fetal bovine serum. The proliferation was assessed by a [3H]thymidine incorporation and direct cell count. We found that IL-1 beta significantly increased thymidine incorporation into and cell count of ASM cells in a concentration-dependent manner. Pretreatment of cells with specific polyclonal antibodies against platelet-derived growth factor (PDGF-BB homodimer) completely inhibited the IL-1 beta-induced increase in thymidine incorporation. The PDGF-BB, at the concentrations of 1.5 and 2.5 ng/ml, stimulated the proliferation of ASM cells. The proliferation action of IL-1 beta was potentiated when PDGF-BB was added into the medium in combination with IL-1 beta. Pretreatment of cells with genistein (0.37 microM), a specific tyrosine kinase inhibitor, attenuated the proliferative effect of IL-1 beta and PDGF-BB. To clarify whether these growth stimuli (IL-1 beta and PDGF-BB) activated phospholipase C (PLC), we examined the formation of phosphatidylinositols. We observed that both agents significantly increased phosphoinositide turnover. In contrast, genistein pretreatment (0.37 microM) prevented formation of inositol 1,4,5-trisphosphate (IP3), as induced by IL-1 beta and/or PDGF-BB. This study demonstrates that both IL-1 beta and PDGF-BB could induce proliferation of ASM cells through the activation of tyrosine kinase and PLC, which in turn stimulate the formation of IP3, a second messenger molecule.
Anti quackery day.
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Is general surgery going the way of dinosaur?
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Pamidronate and uveitis.
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Nonlinear dc electrical response in a bilayer lipid membrane: Effect of bathing solutions.
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IL-1 beta and IL-6 induce hyperplasia and hypertrophy of cultured guinea pig airway smooth muscle cells.
Guinea pig airway smooth muscle (ASM) cells were maintained in a primary tissue culture (passages 1-3). Cells were exposed to human recombinant interleukin-1 beta (IL-1 beta; 20-100 pg/ml) or interleukin-6 (IL-6; 1-4 ng/ml) in the presence of indomethacin (1 microgram/ml) for up to 5 days. Proliferation of ASM cells was assessed with two techniques, direct counting of cells with a hemacytometer and [3H]thymidine incorporation corrected for total protein content. Hypertrophy of ASM cells was assessed by [3H]leucine incorporation (evaluation of protein synthesis), determination of total DNA content, DNA content per cell, and protein content per cell. We observed that the exposure of ASM cells to human recombinant IL-1 beta or IL-6, in all studied concentrations, significantly increased the number of cells as well as [3H]thymidine incorporation into ASM cells. We also found that exposure of ASM to these two cytokines increased [3H]leucine incorporation into the ASM cells and increased protein content and DNA content per single cell. These changes were also concentration dependent. We conclude that the two proinflammatory cytokines, IL-1 beta and IL-6, which are present in asthmatic lungs, increased the proliferation of ASM cells (hyperplasia) as well as their overall size and size of their nuclei, as measured by biochemical markers. These findings are compatible with the presence of ASM hypertrophy.
Investigation of the anti-inflammatory effects of Paederia foetida.
A detailed investigation on the anti-inflammatory activity of the butanol fraction of a methanol extract (BMEL) of the defatted leaves of Paederia foetida was undertaken to find the pharmacological basis for the ethnomedical use of the plant. This fraction produced a significant inhibition of granulation tissue formation in cotton-pellet implanted rats. It decreased liver aspartate transaminase activity without affecting serum aspartate transaminase activity. It did not, however, affect adrenal weight and ascorbic acid content significantly, thus ruling out a stimulation of the adrenal-pituitary axis. BMEL antagonised hyposaline-induced haemolysis of human red blood cells and an elevation of rat serum acid phosphatase activity, indicating the presence of a membrane stabilising activity. It also inhibited the elevation of serum orosomucoid levels in rats, suggesting the possibility of the presence of disease-modifying antirheumatic activity. The results indicate that there is some rationale behind the ethnomedical use of the plant for treating inflammatory disorders.