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Biomedical subjects

M Menon

Publications and source records attributed to M Menon.

At least 73 records · Page 4Linked to original sources
PubMed1994

Posttransplant lymphocele presenting as 'acute abdomen'.

Lymphoceles occurring after renal transplantation are frequently asymptomatic and are usually identified on routine ultrasonography of the allograft. A small percentage of them may increase in size and manifest due to their compression effects on adjacent structures or as lymphocutaneous fistula. An infected lymphocele would, in addition, give rise to local and systemic features. A case of infected lymphocele occurring 4.5 months after cadaveric renal transplant is reported. The patient presented in septicemia and features of generalized peritonitis. Emergency diagnostic laparoscopy revealed fluid collection in the peritoneal cavity. However, on exploratory laparotomy no intra-abdominal pathology was detected. Further evaluation revealed a large perigraft lymph collection which was drained percutaneously. Fluid and blood cultures grew Staphylococcus aureus. The patient recovered completely following external drainage and antibiotic administration.

Abdomen, Acute↗
PubMed1994

Effect of environmental pollutants on hepatocellular function in rats: 3-methylcholanthrene and Aroclor-1254.

Environmental pollutants, Aroclor-1254 (PCB) and 3-methylcholanthrene (MC), were employed in this study to investigate some aspects of the induction of hepatic drug metabolism in rats. PCB and MC treatments increased 7-ethoxyresorufin and 7-ethoxycoumarin O-deethylase activities related to cytochrome P-448. Cytochrome P-450 reductase activity was increased by PCB while no effect was observed by MC treatment. Pretreatment with PCB resulted in approximately 50% increase in the phospholipid content of the microsomes whereas MC caused no change. Liver microsomal cholesterol content was decreased while triglycerides were increased by PCB. The ratio between saturated and unsaturated fatty acids (saturation index) decreased in the total microsomes and phospholipids with PCB treatment, whereas MC did not alter the ratio, except that the major effect of MC was observed in the acyl derivatives of microsomal phosphatidylethanolamine. It is proposed that the uniaxial rotation and mobility of hemoproteins may be restricted by an increase in the saturation index of the membrane, while a decreased index may facilitate contact with reductases for electron transfer by enhanced membrane fluidity. The decreased saturation index after treatment with MC may play a role in carcinogenicity by triggering induction of free radicals.

Animals↗
PubMed1994

Modulation of bile acids induced by paraquat in rabbits.

Rabbit bile was examined for changes in composition induced by paraquat. Paraquat was administered intraperitoneally and changes in bile components were monitored by high performance liquid chromatography. Alterations in the ratios of total glycine/taurine conjugated bile acids (TGC/TTC), cholic acid/deoxycholic acid (CA/DC), cholic acid/chenodeoxycholic acid (CA/CDC) and cholic acid/cholesterol (CA/CH) were measured as an index of paraquat toxicity. A statistically significant increase in the ratio of TGC/TTC was observed, while CA/DC, CA/CDC and CA/CH showed a decrease. Phospholipids, protein, sugar, bilirubin, beta-carotene, vitamin A and vitamin E in the bile and serum of the experimental animals were also monitored. In bile, the levels of cholesterol, phospholipids, protein, sugar, and total bile acids increased while the levels of the antioxidants beta-carotene, vitamin A and vitamin E decreased. A decrease in the bilirubin content of the bile was also observed. These modifications may be useful clinically for assessment of paraquat toxicity.

Animals↗
PubMed1993

[Active uptake of oxalate in a renal tubular cell line (LLC-PK1)].

The oxalate uptake was studied in LLC-PK1 cells, an epithelial cell line originated in proximal tubular cells of porcine kidney. It was clear that the cells contain an oxalate exchanger highly sensitive to 4,4-diisothio-cyanostilbene-2-' disulfonic acid (DIDS). The uptake was inhibited by the addition of inorganic anions (chloride, sulphate and bicarbonate) to the reaction system, but was unaffected by sodium ion. The data suggest the possibility that it should be consistent with at least two transport systems for oxalate in LLC-PK1 cells, a SO4-/oxalate/HCO3- exchanger and a Cl-/oxalate exchanger.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1993

[Some effects of pH, diuretics and organic acids on the uptake of oxalate in a renal tubular cell line (LLC-PK1)].

The effects of changes in extracellular pH and treatments with diuretics or some organic acids on the uptake of oxalate were studied in an epithelial cell line of renal origin (LLC-PK1 cells). The oxalate uptake into the cells exhibited a marked sensitivity to extracellular, pH, in the present results with acidic pH stimulating and alkaline pH inhibiting the DIDS sensitive uptakes. The uptake of oxalate was clearly inhibited by DIDS, proportionally to the concentrations from 10 microM to 1 mM. Furosemide, chlorothiazide, probenecid and acetazolamide inhibited the oxalate uptake significantly. Probenecid has the most potency on the inhibition of the uptake in high concentrations, and acetazolamide needed a high concentration for the small effect. However, allopurinol has no effect on the uptake as well as dicarboxylates (malate, succinate and phenyl succinate) and organic acids (urate and para-amino hippurate). We discussed the mechanisms of the inhibition against the oxalate uptake concerning with each drug. It was suggested that probenecid may inhibit the oxalate carriers directly, while furosemide, chlorothiazide and acetazolamide may inhibit then by the direct actions and some secondary effects which are provided by those drugs.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

Epidermal growth factor: receptor binding and effects on the sex accessory organs of sexually mature male mice.

The role of epidermal growth factor (EGF) in maintaining the integrity of the male sex accessory glands was investigated in the mouse. In the sexually mature male C3H mouse, EGF levels were highest in the submandibular gland, followed by the seminal vesicles and the prostate. Twenty eight days after sialoadenectomy (Sx), EGF fell below detectable limits in the serum and in the seminal vesicles. However, the prostate still retained 22% of its immunoreactive EGF. There was a seven-fold increase in serum testosterone after sialoadenectomy. Despite this drastic rise in testosterone, both prostatic and seminal vesicular weights were reduced, serum levels of LH were suppressed only by 37% and FSH levels were not altered. All these changes were abolished by the simultaneous administration of exogenous EGF at 100 micrograms./kg./day for 28 days. Both prostatic and seminal vesicular membranes contained binding sites for 125I-EGF. Binding was maximal after one hour of incubation at room temperature. Two classes of binding sites were shown for either organ (Kd = 1.2 nM, n = 56 fmol/mg. and Kd = 74 nM, n = 540 fmol/mg. for prostate; Kd = 0.9 nM, n = 29 fmol/mg. and Kd = 93 nM, n = 150 fmol/mg. for seminal vesicle). The binding of 125I-EGF was displaced by excess EGF and TGF-alpha but not by insulin, ILGF-2 and PDGF. These data suggest that EGF may have an important role in maintaining the integrity of the seminal vesicle and the prostate in the mouse. While the seminal vesicle appears to acquire EGF by uptake from the environment, the prostate may have the ability to synthesize EGF locally.

Animals↗
PubMed1992

Short term effects of cis-platinum on male reproduction, fertility and pregnancy outcome.

In order to find out the short term effects of cis-platinum treatment on reproductive function of the treated male rats and their progeny, sexually mature male Sprague-Dawley rats were given a single intra-peritoneal injection of either saline or cis-platinum (2, 4, 8 mg./kg.body wt.). One week following the treatment, the animals were mated with proestrus females of proven fertility. The females were scored positive or negative depending upon whether or not spermatozoa were seen in the vaginal smear after mating. However, all the females were watched until day 18, and on day 19, the females that became pregnant were subjected to laparotomy, and the number of corpora lutea, implantation sites and fetuses were counted. The fetuses were weighted and observed for the presence of any morphological abnormalities. Significant pre-implantation loss was seen in the treated groups. The weights of the fetuses were also significantly lower than those from the control group. Analysis of the effects of cis-platinum on the reproductive system of treated males revealed that cis-platinum reduced the reproductive organ weights, sperm counts, sperm motility, fertility and the levels of testosterone, LH and FSH. These results suggest that cis-platinum has a profound deleterious effect on the reproductive system and on the fertility potential of the treated male rats.

Animals↗
PubMed1992

The mechanism of cyclosporine's action in the inhibition of testosterone biosynthesis by rat Leydig cells in vitro.

We have previously demonstrated that cyclosporine inhibits testosterone (T) biosynthesis in vivo. To better understand the mechanism by which CsA inhibits T synthesis, interstitial cells were isolated from rat testes and incubated in the standard medium 199 with or without CsA (0-10 micrograms/ml) in the presence or absence of human chorionic gonadotropin (hCG, 10(-7) M) and 8-bromo cyclic AMP (cAMP, 0.5 mM) for 3 hr at 32 degrees C. The levels of cAMP and T were determined by RIA. CsA did not inhibit the basal secretion of T, but inhibited hCG-stimulated T production in a dose-dependent manner (4 ng/10(6) cells vs. 10 ng/10(6) cells at a CsA dose of 5 micrograms/ml, P less than 0.05). Radioligand binding of 125I-hLH to testicular membranes was not affected by CsA, as CsA did not compete with hCG/LH for binding sites (25-28% binding with or without CsA). Similarly, the MIX-stimulated cAMP production was not affected by CsA (24.03 +/- 1.09 vs. 20.60 +/- 0.38 pmol/10(6) cells), suggesting that CsA does not inhibit the accumulation of the second messenger. However, when interstitial cells were incubated with CsA in the presence of cAMP, a significant dose-dependent decline in T secretion was observed (7 ng/10(6) cells vs. 20 ng/10(6) cells at a CsA dose of 5 micrograms/ml). To determine whether CsA inhibits the steps beyond cAMP stimulation of T secretion, the kinetic parameters (Km and Vmax) of steroidogenic enzymes, delta 4-3 keto-17 alpha hydroxylase (17 alpha-hydroxylase), and delta 4-3 keto-17 beta hydroxy steroid dehydrogenase (17B-HSD) were determined by using Michaelis Menten analysis. Results are shown in the presence of CsA vs. no CsA: Km and Vmax values for 17 alpha-hydroxylase were (2.32 vs. 7.98 microM) and (27.96 vs. 100.97 pmol/mg protein/min), respectively. For 17B-HSD the Km and Vmax were (2.14 vs. 1.52 microM) and (15 vs. 15 pmol/mg protein/min), respectively. These results indicate that CsA inhibits the activity of 17 alpha-hydroxylase uncompetitively and 17B-HSD activity competitively. In conclusion the primary site for CsA inhibition is the cAMP stimulation and, CsA inhibits T synthesis at multiple sites.

Animals↗
PubMed1992

Clinical and social problems in young women with breast carcinoma.

Studies have noted that Asian women tend to have invasive breast cancer at a younger age compared with their Western counterparts. This is a rising trend among women in Singapore. This study compares 46 women less than or equal to 35 years with 313 women greater than 35 years who were treated in a teaching hospital between January 1983 and December 1989. Despite better education, the younger women (less than or equal to 35 years) were no different from their older counterparts in delaying medical consultation for more than 3 months after self-detection (39 vs 38.6%) though a higher percentage of older women procrastinated for over a year (16.6 vs 6.5%). As a result, 28% of younger women and 21.6% of older women presented with late disease (TNM Stage III and IV). Primary healthcare physicians contributed towards further delay among 65% of women less than or equal to 35 years. They were more suspicious when breast lumps were detected in women greater than 35 years and only 8% had delayed referrals. Failure in advising early biopsy added further delay (greater than 3 months) in 27.6% of younger patients whereas it was seldom delayed for the other older group (0.3%). Eight patients less than or equal to 35 years were initially reluctant to undergo definitive surgery. These cumulative delays resulted in progression of disease in seven patients of the 11 patients whose therapy was delayed more than 6 months.

Adolescent↗
PubMed1992

Modification of liver and serum enzymes by paraquat treatment in rabbits.

Paraquat (PQ) is known to cause progressive interstitial fibrosis in the lungs. Previous investigations have indicated that PQ acts by lipid peroxidation of the membrane. However, there are few reports on the action of PQ on hepatic enzymes. This work was carried out to investigate the modulation of various hepatic enzymes by PQ in rabbits. Paraquat was administered at a dose of 3, 6 or 12 mg/kg b. wt/day intraperitoneally to male rabbits for different periods of time. Administration of paraquat resulted in a significant decrease in plasma activities of transaminase enzymes, alkaline phosphatase and liver transketolase. No significant change was found in the activities of plasma and hepatic lactate dehydrogenase and alkaline phosphatase. A marked increase in blood glucose was noticed 48 hours after paraquat administration.

Alanine Transaminase↗