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Biomedical subjects

M Menon

Publications and source records attributed to M Menon.

At least 145 records · Page 8Linked to original sources
PubMed1985

The role of plasma lipoproteins in steroidogenic response of rat luteal cells during gonadotropin-induced refractory states.

Administration of human chorionic gonadotropin (hCG) to pregnant mare's serum gonadotropin--hCG primed rats results in the loss of in vitro responsiveness of the ovaries to exogenous gonadotropins for progesterone production. This state is associated with a loss of membrane receptors for hCG and a concomitant increase in lipoprotein receptors. Although lipoproteins potentiated gonadotropin response in ovaries from saline-injected rats, no stimulation was observed in hCG-desensitized ovarian cells. Examination of the time course for the loss of lipoprotein response after hCG injection revealed that injection with 50 IU of hCG results in a loss of gonadotropin response as early as 1 h after injection, but exogenous cholesterol-carrying lipoprotein fractions, LDL and HDL, were capable of stimulating progesterone production up to 4 h after hormone injection. Measurement of endogenous cholesteryl ester content showed that there was a 72% decline during this period with a concomitant increase in the basal progesterone production. One hour after hCG injection there was no stimulation of steroidogenesis by hCG in the presence or absence of exogenous lipoproteins. The refractoriness to exogenous hCG appeared only 4 h later when the hCG dose was reduced to 10 IU, whereas with 25 IU of hCG, the effect was similar to that observed using 50 IU of hCG. Such diverse steroidogenic stimuli as hCG, LH, LDL, cAMP, and cholera enterotoxin failed to stimulate progesterone synthesis in vitro in luteal cells of rats injected with 50 IU of hCG 48 h prior to sacrifice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

"Pan-myeloid" reagent: the monoclonal antibody MCS-2 in the routine immunodiagnostic service of leukemia phenotyping.

This retrospective analysis describes the reactivity of several monoclonal antibodies (MoAbs) which detect myelomonocytic antigens of the cells of 182 leukemias. These leukemias were assigned to definite subtypes of lymphocytic and myelo(mono)-cytic leukemias on the basis of standard leukemia phenotyping using morphological, cytochemical, isoenzymatic and mainly immunological criteria. The MoAb MCS-2 was negative in all cases of lymphocytic leukemia, whereas two of the three other commonly used "myeloid MoAbs" MCS-1, OKM-1 and 1/12/13 showed positivity in B-chronic lymphocytic leukemia (B-CLL), B-lymphoma (MCS-1), T-acute lymphoblastic leukemia (T-ALL) and Sézary syndrome (OKM-1). MCS-2 was positive in all samples of acute myelomonoblastic leukemia (AMMoL), chronic myelocytic leukemia (CML) and CML-myeloid blast crisis, which was not the case for MCS-1, OKM-1, or 1/12/13. In 14 cases (11 acute myeloblastic leukemia (AML), 3 CML-myeloid blast crisis) where MCS-2 was positive and one or all of the three other MoAbs were negative, the cells were mainly Ia-positive and peroxidase-negative. MCS-2 is a diagnostically important MoAb in the routine leukemia phenotyping of myelomonocytic leukemias. After having tested a large number of normal and malignant specimens, we would like to term MCS-2 a "pan-myeloid MoAb" reacting with the myelomonocytic cell lineage from the earliest myeloblast to granulocytes and monocytes.

Antibodies, Monoclonal↗
PubMed1984

Sterilization failures with bipolar tubal cautery.

From a consecutive series of 105 patients undergoing bipolar tubal sterilization (BPS), ten pregnancies were reported, and a tubal patency rate of 16% was found at hysterosalpingography. There were no significant clinical variables separating the BPS failure patients from those with successful sterilization. Ninety percent of the BPS failures were intrauterine, and 90% occurred within three cycles of BPS. The results of this investigation suggest that (1) BPS tubal occlusion may be associated with an increased failure (pregnancy and tubal patency) rate; (2) the majority of BPS failures are intrauterine gestations; (3) delayed fibrosis, rather than immediate tubal destruction, may be the mechanism of BPS tubal occlusion; (4) for maximum effectiveness, patients undergoing BPS should use alternative contraception for two to three cycles; and (5) surgeons employing BPS require precise training in the application of this modality of female sterilization.

Cautery↗
PubMed1984

Effect of orchiectomy and ovariectomy on oxalate production, transport and excretion in rats.

The role of sex hormones on oxalate synthesis by liver, transport by renal cortical mitochondria and urinary excretion was studied in adult male and female Sprague-Dawley rats. Orchiectomy decreased the hepatic synthesis of oxalate whereas ovariectomy increased it by 10 per cent. Castration inhibited oxalate transport by the renal mitochondria uncompetitively in both sexes. Urinary levels of oxalate were unaffected after orchiectomy whereas ovariectomy resulted in an initial elevation in the urinary oxalate levels which returned to control values by 21 days. The results are discussed in light of recent data.

Animals↗
PubMed1984

Collection and handling of 24-hour urine specimens for measurement of analytes related to renal calculi.

Analysis for calcium, magnesium, phosphorus, oxalate, uric acid, and creatinine in 24-h urine collections is often needed for the differential diagnosis of patients with renal calculi. Considerable attention has been given to improving the methods of analysis, but improper sample collection and processing can cause significant errors for calcium and oxalate in urine samples not treated with acid and for uric acid in urine samples not treated with base. The errors are related to the concentration of the analyte, the interval the sample is stored before analysis, and the original pH of the urine sample. We describe here a system of sequential acidification (to pH 1.5) and alkalinization (to pH 9) of 24-h urine samples, followed by heating at 56 degrees C for 10 min. This procedure allows accurate analysis for all the above analytes in the same 24-h collection of urine. We validated the sample-treatment protocol for 80 24-h urine collections.

Calcium↗
PubMed1983

Lack of value of radioimmunoassay for prostatic acid phosphatase as a screening test for prostatic cancer in patients with obstructive prostatic hyperplasia.

We examined the incidence of prostatic cancer in patients with an elevated radioimmunoassay for prostatic acid phosphatase and clinical benign prostatic hyperplasia on digital rectal examination. Of 295 patients screened with prostatic acid phosphatase tests 17 fulfilled the criteria of having an elevated prostatic acid phosphatase, clinically benign prostate and histological examination of the prostatectomy specimen. None of the 17 patients had histological evidence of prostatic cancer. The results confirm the predictions of mathematical models that prostatic acid phosphatase is of no practical value as a screening test for prostatic cancer in patients with clinical benign prostatic hyperplasia.

Acid Phosphatase↗
PubMed1983

Pelvic lymph node status as predictor of extracapsular tumor extension in clinical stage B prostatic cancer.

To examine the accuracy of normal pelvic lymph node status in identifying patients with clinical stage B prostatic cancer not having extracapsular tumor extension we reviewed 63 consecutive patients (39 stage B1 and 24 stage B2) treated with radical prostatectomy. Ten per cent of the patients with stage B1 lesions (tumor involving 1 lobe) and 38 per cent with stage B2 lesions (tumor involving both lobes) had extracapsular extension. Extracapsular tumor extension was more common in patients with larger, less differentiated lesions. The results suggest that a negative pelvic lymphadenectomy does not exclude with a high degree of confidence extracapsular tumor extension in patients with clinical stage B2 prostatic cancer.

Genital Neoplasms, Male↗
PubMed1983

Urinary citrate excretion in patients with renal calculi.

Urinary citrate excretion was measured with a specific enzymatic technique in normal subjects and in an unselected group of patients with recurrent calcium oxalate stones. Hypocitraturia (citrate levels less than those present in 95 per cent of the normal population) was detected in 7 of 46 patients with stones (15 per cent). Hypocitraturia was the only metabolic abnormality in 6 patients.

Adult↗
PubMed1983

Ion-chromatographic measurement of oxalate in unprocessed urine.

We describe a sensitive, simple technique for determining urinary oxalate. Urine, diluted as necessary with distilled water, is injected into an ion chromatograph. Oxalate is detected conductimetrically as a distinct peak near the tail of the chromatogram. This peak specifically represents oxalate, because it is abolished if the sample is treated with oxalate decarboxylase. We have used this technique to measure oxalate in more than 3000 consecutively received urine samples. It has a CV of 6%.

Carbonic Acid↗
PubMed1983

Assay of urinary oxalate: six methodologies compared.

To assess how well results by different methods for urinary oxalate determinations agree with each other in a clinical setting, we compared six different assays: Hodgkinson and Williams (Clin Chim Acta 36:127-132, 1972), enzymatic, modified Hodgkinson and Williams, gas chromatography, ion chromatography, and "high-pressure" liquid chromatography. For the entire group of samples, the mean value by each method agreed relatively closely, although the enzymatic procedure produced a somewhat higher value. All six methods had large coefficients of variation within (8-58%) and between (15-88%) assays. In addition, analytical recovery by most assays was more than 100% of the added oxalate. Analytical recovery of 10 micrograms of oxalate added per milliliter of urine specimen ranged from 86 to 237%; for 20 micrograms/mL it was 83 to 320%. Thus for the six methods evaluated, no single method appeared to be superior to the others.

Chromatography, Gas↗
PubMed1983

Evaluation and medical management of the patient with calcium stone disease.

About 80 per cent of renal stones seen in the western hemisphere are composed of calcium and oxalate. The authors discuss some of the metabolic disorders involved in calcium stone disease, describe a comprehensive metabolic work-up for the patient who forms stones recurrently, and suggest some guidelines for treatment.

Adult↗
PubMed1982

Undiverting the ileal conduit.

From 1975 to 1981, 46 patients were evaluated for urinary undiversion. Of these patients 27 completed urinary reconstruction. The patients have been followed for 6 to 80 months, with a mean followup of 32 months and a median followup of 23 months. There has been no death and no rediversion has been necessary, although in 1 patient renal function has deteriorated significantly following urinary reconstruction. Postoperative bladder function was normal in patients diverted for dysfunctional voiding or bladder outlet obstruction but children with meningomyelocele required intermittent catheterization postoperatively. With careful patient selection, meticulous surgical technique and compulsive followup urinary undiversion is a safe procedure.

Adolescent↗
PubMed1982

Oxalate metabolism and renal calculi.

Changes in oxalate excretion (together with changes in urinary volume) constitute the most important factors in altering the probability of renal stone formation. However, investigations on oxalate metabolism have been sparse, perhaps because of the lack of an accurate method for measuring oxalate in biologic fluids. Available data clearly implicate increased urinary oxalate excretion as the etiological factor in stone formation in two groups of patients--those with primary hyperoxaluria and those with gastrointestinal malabsorption. Evidence for the existence of hyperoxaluria in the patient with the "garden" variety of calcium oxalate stones is less persuasive.

Animals↗
PubMed1982

Determination of urinary oxalate by ion chromatography: preliminary observation.

The technique of ion chromatography was applied to determine oxalate concentrations in unprocessed urine. The minimal detectable limits of oxalate was 1 microgram./ml. (11 mumole/liter), the within-run imprecision (Sw) was 2.3 per cent and the total imprecision (St) was 4.9 per cent. Ion chromatography can be used for the simple, accurate and direct measurement of urinary oxalate.

Adult↗