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Biomedical subjects

S Lakshmi

Publications and source records attributed to S Lakshmi.

32 records · Page 2Linked to original sources
PubMed1999

Effect of cigarette smoke on lipid peroxidation and antioxidant enzymes in albino rat.

Effect of cigarette smoke on lipid peroxidation (LPX) and antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) in various organs like brain, heart, lung, liver and kidney of the albino rats exposed to cigarette smoke for 30 min/day for a period of 30 days were assayed. It was observed that the lipid peroxide levels in liver, lung and kidney were enhanced in case of animals exposed to cigarette smoke, whereas brain and heart did not show any change as compared to control animals. The activity of the antioxidant enzymes was also elevated in liver, lung and kidney of the test animals whereas, brain and heart did not show any change in the activities of all of these antioxidant enzymes except glutathione-s-transferase which was increased in brain also. The level of reduced glutathione (GSH) was lowered in liver, lung and kidney of the tested animals when compared with the control animals but there was no significant change in brain and heart. The results of our study suggest that cigarette smoke induces lipid peroxidation in liver, lung and kidney, and the antioxidant enzymes levels were enhanced in order to protect these tissues against the deleterious effect of the oxygen derived free radicals. The depletion of reduced glutathione in these organs could be due to it's utilization by the tissues to mop off the free radicals.

Animals↗
PubMed1998

Migration resistant, blood-compatible plasticized polyvinyl chloride for medical and related applications.

Plasticized polyvinyl chloride (PVC), although not a blood-compatible polymer, is the material of choice for the manufacture of blood bags and hemodialysis tubing throughout the world. PVC is usually plasticized with di-(2-ethylhexyl phthalate) (DEHP) to impart flexibility and low temperature properties to the final product. DEHP belongs to a class of agents called hypolipidemic hepatocarcinogens, and it migrates in small quantities into the storage medium such as blood, plasma, or serum, resulting in a number of toxic effects. It has been shown that the migration resistance and blood compatibility of flexible PVC could be significantly improved by grafting polyethylene glycol (PEG), the most blood-compatible polymer known today, onto the surface of flexible PVC by the classical Williamson ether synthesis reaction. The technique is simple and versatile enough to produce blood-compatible, migration resistant PVC surfaces for many medical applications. The method may also find use for preventing plasticizer migration from PVC cling films and polyvinylidene chloride films used extensively in food packaging.

Animals↗
PubMed1998

High-risk human papillomavirus infection and E6 protein expression in lesions of the uterine cervix.

Pathologic and epidemiologic investigations carried out over the past several years have provided evidence that carcinogenesis in the uterine cervix is a multi-step process involving discreet preinvasive stages. Molecular epidemiologic data also indicate that human papillomavirus (HPV) infection is a critical factor in the tumor progression process. In vitro studies have shown that for the initiation and maintenance of the malignant phenotype, the expression of the HPV-transforming protein E6 is required. The E6 protein produced by the high-risk HPV types 16 and 18 can bind to and inactivate the tumor suppressor protein p53 leading to deregulated proliferation and defective apoptosis, thus facilitating tumor progression. Therefore, determination of the HPV genotype alone may not be sufficient in assessing tumor progression in the uterine cervix. In the present study, a total of 623 cervical tissue samples at various phases of tumor progression were assessed for HPV infection by nonisotopic in situ hybridization (NISH) and for HPV 16/18 E6 protein expression by immunocytochemistry. There was significant correlation between the extent of histological abnormality and HPV infection. Significant correlation (r = 0.707, p = 0.000) was observed between the presence of HPV 16 and high-grade squamous intraepithelial lesions (SILs) and invasive cancer. The odds ratio of a cervical tissue infected with HPV 16 falling into these two categories was 44.57 (95% CI: 27.10, 73.30). The E6 protein also was mostly detected in high-grade SILs and cervical cancer tissue expressing either HPV 16 or 18. It was less frequent in low-grade SILs infected with HPV 16/18 and was absent in benign cervical tissue infected with HPV 16. The odds ratio of an HPV-16/18-infected cervical tissue positive for E6 being a high-grade SIL or invasive cancer was 16.20 (95% CI: 6.06, 43.33). These results thus show the clinical utility of HPV characterization along with the analysis of the transforming protein E6 in the assessment of tumor progression in the uterine cervix.

Adult↗
PubMed1997

c-erbB-2 oncoprotein and epidermal growth factor receptor in cervical lesions.

Epidermal growth factor receptor (EGF-R) and the oncogene product of c-erbB-2 have been shown to be expressed in human tumors and in some cases relate to clinical outcome. This study investigates the correlation between the presence of these receptor proteins and various histological grades of cervical tissues. Immunocytochemical analysis of benign, premalignant and malignant cervical tissues showed a highly significant correlation between the expression of the two proteins and the histological grade of the lesions. Moreover, the overall frequency of coexpression of these proteins was similar. This study suggests that these proteins may be involved in cellular proliferation and have a significant role in the progression of cervical cancer.

Carcinoma in Situ↗
PubMed1997

p53 protein and tumorigenesis in the uterine cervix.

The relationship between molecular abnormalities of p53 tumor suppressor gene product and cancer has been well documented. That correlation may exist between immunocytochemically detectable amount of p53 protein and neoplasia is evidenced by several studies. Detection of p53 protein by immunocytochemistry varies depending on the methods and antibodies used. It has been suggested that the quantitative aspect of p53 protein expression and the proportion of cells expressing p53 may be of clinical importance in human malignancies. In the present study, we have examined the expression of p53 protein in various grades of lesions of the uterine cervix. Statistical analysis showed a good correlation between expression of p53 protein and histologic grade of lesions. Increased expression of p53 in dysplastic and malignant lesions compared to non dysplastic lesions suggests that p53 protein accumulation may be an early event in carcinogenesis.

Cell Nucleus↗
PubMed1996

Stopped-flow kinetic investigation of the oxidation of ascorbic acid by iron (III) benzohydroxamic acid.

The fast oxidation of ascorbic acid by Fe(III)benzohydroxamic acid complex [Fe(BHA)3] has been investigated by the stopped-flow technique in aqueous ethanol medium at three pH values (4.6, 7.0, and 9.0). The reaction exhibits a first-order dependence of rate each on [ascorbic acid] and [Fe(BHA)3], obeying Michaelis-Menton kinetics. The rate of the reaction was found to be pH-dependent.

Ascorbic Acid↗
PubMed1993

Oral cancer and human papillomaviruses: is there a link?

Cancer of the oral cavity accounts for almost 56,000 new cases in India each year totalling almost 30% of all cancer cases in the country. Despite the numerous advances in etiology and epidemiology, the mechanisms involved in oral carcinogenesis remain obscure. Current research has provided some provocative results, suggesting an association between human papillomavirus (HPV) and development of squamous cell tumors including oral cancer. Evidence has been presented showing HPV infection of the oral mucosa and its relation to neoplastic changes. However a clear cut association as is evident in the uterine cervix is not yet available. However, considering the many similarities between oral and cervical oncogenesis, many of the HPV induced changes in the cervix may also be applicable to the oral mucosa. This paper studies the evidence for the possible role of HPV infection in oral carcinogenesis, the uterine cervix as a model for HPV mediated carcinogenesis, and tries to determine if similar mechanisms could exist in both cases.

Female↗
PubMed1981

The distribution of estrone sulphatase, dehydroepiandrosterone sulphatase, and arylsulphatase C in the primate (Macaca radiata) brain and pituitary.

Estrone sulphatase, arylsulphatase C and dehydroepiandrosterone sulphatase were measured in the pituitary, hypothalamus-preoptic area, amygdala, hippocampus, midbrain, septum, frontal cortex and occipital cortex of monkey (Macaca radiata) brain. All the regions showed measurable activities of all three enzymes. In all the animals tested, either the midbrain or hypothalamus-preoptic area showed the greatest activity of all three enzymes. In particular, estrone sulphatase showed the highest specific activity in either of the above two regions in all animals. Subcellular distribution studies in the hypothalamus preoptic area showed a similarity in the distribution profile between arylsulphatase C and estrone sulphatase and a significant difference of dehydroepiandrosterone sulphatase from the others.

Animals↗
PubMed1980

Soluble arylsulfatases of human brain and some characteristics of the brain-specific arylsulfatase Bm.

The brain-specific arylsulfatase Bm (aryl-sulfate sulfohydrolase, EC 3.1.6.1) was demonstrable in human and monkey brain. Arylsulfatases A, B and Bm were separated employing DEAE-cellulose chromatography. There was a distinct difference in the proportion of the sulfatases in infant and adult human brain. Arylsulfatase Bm after concanavalin A-Sepharose chromatography showed the property of binding to Sephadex G-200 totally. Several dissociating agents failed to elute the enzyme from the bound form. Under similar conditions arylsulfatase A did not show any binding to Sephadex. On treatment with Escherichia coli alkaline phosphatase adult human brain arylsulfatase Bm but not arylsulfatase A was converted into a less acidic, presumably dephosphorylated form that did not bind to DEAE-cellulose. Monkey brain arylsulfatase Bm showed a similar susceptibility to E. coli phosphatase treatment. Inorganic phosphate and serine phosphate but not mannose 6-phosphate could inhibit this dephosphorylation. There were differences in the susceptibilities to alkaline phosphatase treatment of the arylsulfatase Bm from infant and adult human brain. Endogenous phosphatase also seemed to have a role on the phosphorylated state of arylsulfatase Bm.

Adult↗
PubMed1979

Studies on the chaotropically solubilized arylsulfatase C and estrone sulfatase of sheep brain.

Arylsulfatase C (aryl-sulfate sulfohydrolase, EC 3.1.6.1) from sheep brain acetone powder was solubilized with the chaotropic agent, KSCN. Anti-chaotropes such as (NH4)2SO4 or sodium citrate significantly enhanced the activity of the solubilized enzyme indicating that hydrophobicity was an important factor influencing the enzyme activity. Dialysis or gel filtration of the solubilized enzyme resulted in a marked loss of activity. 3a dialyzable activator could reconstitute the activity in the presence of the antichaotropes. The activator was purified partially and preliminary studies indicated it to be a low molecular weight peptide. Arylsulfatase C and estrone sulfatase activities were compared in the solubilized enzyme. Estrone sulfatase activity was also increased in the presence of antichaotropes at lower concentration in comparison to arylsulfatase C. It however did not show a requirement for the dialyzable activator. Kinetic studies showed that elevation of enzyme activity by the antichaotropes and activator in the case of arylsulfatase C and by antichaotropes in the case of estrone sulfatase was due to an increase in V with a decrease in Km.

Ammonium Sulfate↗