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Biomedical subjects

M Menon

Publications and source records attributed to M Menon.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1991

A new model of nephrolithiasis involving tubular dysfunction/injury.

To better understand the pathogenesis of nephrolithiasis, we developed a new animal model that closely mimics human calcium oxalate stone disease. Rats were treated with a regimen that combines moderate hyperoxaluria (produced by 10 days of feeding with 3% ammonium oxalate) with mild proximal tubular injury/dysfunction (produced by 8 daily injections of gentamicin sulfate -40 mg./kg.). This combined treatment caused a marked increase in the incidence of calcium oxalate crystals and stones over that seen in animals treated with oxalate or gentamicin alone. Using a semiquantitative scoring system for estimating the abundance of crystals in coronal sections of kidneys, we found that 63% of animals receiving gentamicin plus oxalate showed "moderate" numbers of crystal, as compared to 8% of animals receiving oxalate alone; and the majority of the crystals occurred in the papilla, a pattern similar to that seen in human stone disease. Untreated rats and rats treated with gentamicin alone did not exhibit calcium oxalate crystals or stones. Despite the abundance of crystals and stones, animals receiving gentamicin plus oxalate retained relatively normal renal function as judged by creatinine clearance. Thus, the model has several advantages over preexisting models of nephrolithiasis. Crystal and stone deposition develop rapidly (within 14 days). The pattern of deposition resembles that seen in human stone disease and renal function remains relatively normal. These findings indicate that this model of nephrolithiasis may prove useful for studies of the pathogenesis of stone disease. Moreover, they suggest that renal tubular injury and/or dysfunction may produce conditions conducive to the formation and growth of calcium oxalate stones.

Animals↗
PubMed1991

Oxalate transport in renal tubular cells from normal and stone-forming animals.

To investigate the cellular mechanism(s) underlying kidney stone disease, we examined oxalate uptake in suspensions of renal cortical and papillary cells derived from control and stone-forming animals. In control animals, both cortical and papillary cells exhibited a time-dependent accumulation of oxalate. This uptake was mediated both by passive diffusion and by one or more transport processes sensitive to the anion transport inhibitor, DIDS. Oxalate uptake was also markedly sensitive to extracellular pH, showing increased uptake at acidic pH outside (pHo) (6.0), and reduced uptake at alkaline pHo (8.0). In renal tubular cells from stone-forming animals, oxalate uptake was markedly altered. Uptake was significantly reduced in cortical cells, whereas it was significantly stimulated in papillary cells from the same animals. Since the observed changes in oxalate handling occurred only in stone-forming animals, it is possible that alterations in renal cell oxalate transport contribute to calcium oxalate stone formation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1990

Influence of dietary fat on fecal mutagenicity in premenopausal women.

A dietary intervention study was conducted on 31 premenopausal women (age: 20-40 years) to investigate the relationship between dietary fat and fecal mutagenicity. After a free-living period (baseline) of one menstrual cycle, the subjects were placed on a high-fat diet (40% calories from fat) for 4 menstrual cycles, followed by a low-fat diet (20% calories from fat) for 4 menstrual cycles. One-half of the subjects were randomly assigned throughout the study to a diet with a P:S ratio of 1.0 while the other half was assigned to one with a P:S ratio of 0.3; body weight by group remained constant. Three-day stool samples were collected at the mid-follicular period during the free-living phase and during the 4th menstrual cycle of each of the 2 controlled diet periods. Mutagenicity was assayed by the SOS chromotest. Reduction of dietary fat was accompanied by a significant decrease in fecal mutagenicity in both P:S groups. Combined values, i.e., both P:S groups, were 20.3 units for high-fat diets vs. 8.78 for low-fat diets.

Adult↗
PubMed1990

Reversal of the toxic effects of cyclosporine on male reproduction and kidney function of rats by simultaneous administration of hCG + FSH.

We have shown earlier that the administration of cyclosporine impairs testicular function and causes a decrease in sperm counts, sperm motility and fertility. In order to determine whether or not the deleterious effects of CsA could be reversed by hormonal therapy, we injected sexually mature male Sprague Dawley rats with cremaphor + saline or CsA (40 mg./kg./d) alone or in combination with human chorionic gonadotropin (hCG; five micrograms./d/rat) and follicle stimulating hormone (FSH; five micrograms./d/rat). The injections were given subcutaneously for 14 days. As expected, CsA administration decreased the body and reproductive organ weights, testicular and epididymal sperm counts, sperm motility and fertilizing ability. Serum levels of LH were elevated and testosterone was decreased. The administration of FSH + hCG to the CsA treated rats restored the body and reproductive organ weights, sperm counts and motility. Seventy five percent of gonadotropin treated males were fertile as compared to 25% in the CsA treated group. In the hormone treated group, the blood levels of CsA were 50% of that of CsA treated group. In order to verify whether or not the decline in the blood levels of CsA was the cause for the amelioration of CsA-induced changes in the reproductive function, we compared the CsA + hormone treated group with another group treated with five mg./kg./d CsA which had blood levels of CsA comparable to the former group. In the five mg./kg./d group the reproductive functions were significantly lower than the CsA + hormone treated group suggesting, therefore, that the restoration of reproductive functions in the CsA + hormone treated group is a result of hormonal treatment. Administration of CsA (40 mg./kg./d) reduced the kidney weight and increased the levels of serum creatinine: these changes were also ameliorated by the administration of hCG + FSH.

Animals↗
PubMed1990

Evaluation of the effect of experimental cyclosporine toxicity on male reproduction and renal function. Reversal by concomitant human chorionic gonadotropin administration.

Administration of cyclosporine to rats has been shown to impair testicular function, resulting in a decrease in sperm counts and fertility. In order to determine whether or not the deleterious effects of CsA could be reversed by hormonal therapy, mature male Sprague Dawley rats were treated with CsA (40 mg/kg/day, s.c.) alone or in combination with human chorionic gonadotropin (hCG) (5 micrograms/day/r; s.c.) for 14 days. Cyclosporine administration decreased the body weight (290 +/- 5.30 vs. 339 +/- 8.7 g; P less than 0.05) and reproductive organ weights (testis 1.49 +/- 0.42 vs. 1.60 +/- 0.03 g; epididymis 0.41 +/- 0.02 vs. 0.49 +/- 0.002 g; seminal vesicle 0.61 +/- 0.09 vs. 1.60 +/- 0.05 g; prostate 0.28 +/- 0.04 vs. 0.60 +/- 0.06 g; P less than 0.05) testicular sperm counts (5.80 +/- 0.42 vs. 8.49 +/- 0.48 x 10(7)/100 mg tissue; P less than 0.05) and epididymal sperm counts, (28.2 +/- 0.95 vs. 51 51.62 +/- 2.17 x 10(7)/100 mg tissue; P less than 0.05) and fertility (25% vs. 100%). Serum levels of LH were elevated (101.98 +/- 21.48 vs. 25.6 +/- 5.18 ng/ml; P less than 0.05) and testosterone was decreased (0.48 +/- 0.07 vs. 2.06 +/- 0.56 ng/ml; P less than 0.05). The administration of hCG to the CsA-treated rats restored the reproductive organ weights (testis 1.56 +/- 0.043 g; seminal vesicle 1.04 +/- 0.05 g; prostate 0.70 +/- 0.06 g) and sperm counts (testicular 7.88 +/- 1.0 x 10(7)/100 mg tissue; epididymal 59.86 +/- 4.16 x 10(7)/100 mg tissue; P less than 0.05) Serum levels of testosterone (18.63 +/- 4.45 ng/ml) and LH (431.65 +/- 31.41 ng/ml) were significantly elevated, as compared with control and CsA-treated groups (P less than 0.05). All the rats in the gonadotropin-treated group were fertile, as compared with 25% in the CsA-treated group. CsA reduced the kidney weight (1.17 +/- 0.02 vs. 1.27 +/- 0.03 g; P less than 0.05) and increased the levels of serum creatinine (0.97 +/- 0.07 vs. 0.59 +/- 0.03 mg/dl; P less than 0.05): these changes were ameliorated by the administration of hCG (kidney weight 1.35 +/- 0.03 g; creatinine 0.76 +/- 0.09 mg/dl).

Animals↗
PubMed1990

[The value of a child abuse observation clinic. Report of an experience in the area of Grenoble].

In France the epidemiology of child abuse is badly known, because of the lack of connexion between different institutions. We present a child abuse observatory set up in Grenoble in May 1987. The social, educational, judicial and medical department's services are working together. In the first 20 months, 87 cases were recorded: 57 physical abuse, 26 sexual abuse and 5 cases of abuses due to negligence. Precise information was collected concerning the victims, their siblings, the family's risk factor and the offenders, the method by which the information was obtained and the prosecution undertaken. A 10 July 1989 law enforced each Department's governor to set up a service for collecting information about child abuse. Our observatory will serve as a model for this law application.

Child↗
PubMed1989

Radiosensitivity of human prostate cancer and malignant melanoma cell lines.

The relative radioresponsiveness of human prostate cancer compared to malignant melanoma is well known. The effects of beta-estradiol or testosterone on the X-irradiation survival of several human cell lines were studied, including: human prostate carcinoma cell lines PC3 and DU145 and human malignant melanoma cell lines A375 and A875. Lines PC3 and DU145 demonstrated 55-61 fmol per 10(6) cells of androgen receptor with no detectable estrogen or progesterone receptor. Cells were irradiated at 120 cGy/min dose rate. There was no detectable toxicity of up to 10(-4) M testosterone or beta-estradiol on PC3 or DU145 cells in the absence of X-irradiation. At plating efficiencies from 11-13%, and plating densities of 1 x 10(4) cells per 60 cm2 flask, cell lines PC3 and DU145 demonstrated a Do of 108.5 +/- 6.5, n 2.1 +/- 0.7 cGy, and Do of 143.5 +/- 1.5 cGy, n 2.4 +/- 0.5, respectively. The addition of testosterone or beta-estradiol at 10(-4) to 10(-10) M prior to or after, X-irradiation did not alter radiosensitivity. At the same dose rate of 120 cGy/min, malignant melanoma cell lines A375 and A875 had a Do of 125 +/- 2.5 cGy, n 1.56 +/- 0.8 SF2 0.65 +/- 0.03 and line A875 demonstrated a Do of 129 +/- 4.5 cGy, n 1.58 +/- 0.4 SF2 0.55 +/- 0.04, respectively. The radiosensitivity of melanoma cell lines did not decrease at low dose rate 5 cGy/min. Thus, the in vitro radiosensitivity of androgen receptor positive prostate cancer cell lines is not necessarily altered by the presence of androgen before or after irradiation. The data support the concept that all malignant melanoma cell lines do not show a broad-shouldered cell survival curve in vitro and intrinsic cellular radioresistance.

Cell Survival↗
PubMed1989

Etiological factors in pediatric stone recurrence.

We followed 270 pediatric stone patients during a 27-year period to determine the recurrence rate of stone disease. Stone disease recurred in 42 patients (16 per cent). When these patients were categorized according to etiology of the stone disease the recurrence rates were infection 14 per cent, idiopathic 14 per cent, anatomical 27 per cent and metabolic 30 per cent. The most prolonged interval to stone recurrence in each category ranged from 7 to 13 years and, thus, long-term followup of pediatric stone patients seems to be important.

Child↗
PubMed1989

Effect of oxalate on function of kidney mitochondria.

The effects of oxalate on kidney mitochondria were evaluated in vitro to test whether oxalate exposure leads to derangement(s) in mitochondrial function that could in turn promote the formation of kidney stones. Our previous studies demonstrated that oxalate is transported across the mitochondrial membrane via the dicarboxylate carrier. The present studies indicated that oxalate competitively inhibits the uptake and oxidation of exogenous malate and succinate in isolated mitochondria but has no effect on mitochondrial respiration in the presence of a mixture of glutamate plus malate or glutamate plus pyruvate. Oxalate attenuates the increase in mitochondrial respiration produced by the uncoupler CCCP or by the Ca2+ ionophore A23187, and the latter effect is more pronounced in kidney than in liver mitochondria. The apparent Ki of oxalate for the response to Ca2+ ionophore is 1.9 +/- 0.3 mM in kidney and 6.1 +/- 0.2 mM in liver mitochondria. Similarly, the ability of oxalate to attenuate calcium-induced swelling of mitochondria is more dramatic in kidney than in liver mitochondria (apparent KiS of 1.7 +/- 0.1 and 18.2 +/- 0.7 mM, respectively). Oxalate has no effect on the rate of calcium uptake by energized mitochondria or on the rate of ruthenium red-insensitive calcium efflux from mitochondria in either tissue. The above findings indicate that oxalate interacts with the inner mitochondrial membrane or with processes controlling membrane integrity to a greater extent in kidney than liver mitochondria. The effects of oxalate on membrane permeability or integrity may be more important than its effects on mitochondrial energy production or calcium sequestration in the pathogenesis of calcium oxalate microlith formation in the kidney.

Animals↗
PubMed1989

A comparison of patients and patient complaints at six chiropractic college teaching clinics.

A cooperative study was undertaken by six chiropractic colleges for the purpose of studying similarities and/or differences among the patients and patient complaints at the college outpatient (teaching) clinics. There were some notable differences among the clinics with respect to the standard demographic variables of age, education, employment and income. The sociodemographic characteristics of patients appeared to be different to the extent that the characteristics of the neighborhoods in which the clinics were located were different. Patients referred to the clinics by chiropractic student/interns were more likely to attend for routine physical exam than patients referred by other sources. Although marked differences were observed in patient attendance for routine physical examination, the health problems for which patients sought treatment were very similar among all the clinics. Low back complaints were the most frequently reported health complaint. The characteristics of the low back complaints were very similar at all six sites.

Ambulatory Care Facilities↗