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Biomedical subjects

M Raman

Publications and source records attributed to M Raman.

10 recordsLinked to original sources

Perforating disorders: summary notes.

The intention of the Summary Notes section is to provide the practitioner and trainee with a current, concise reference source to dermatologic diseases and to serve as a form of Continuing Medical Education. Each installment will deal with a specific disease. When included, the pretest questions indicate some of the areas to be covered and will challenge your present knowledge of the material before reading further. The self-assessment post-test questions appear on page 18; the answers are on page 25.

Humans↗

Severe falciparum malarial complications in Ukhrul, Manipur.

Development of complications is very common among the patients suffering from Plasmodium falciparum infection. A total of 64 patients of Plasmodium falciprum infections were admitted to the District Hospital, Ukhrul, during the period of 1st May 1996 to 15th June 1999; 9.37% patients do not develop complication while the rest 90.63% developed one or more complications. The most common complication is anaemia accounting for 76.56% followed by cerebral malaria (59.38%). Other lesser complications were leucopenia (15.63%), thrombocytopenia (26.56%), adult respiratory distress syndrome (6.25%). There is no single record of blackwater fever, 12.5% died due to development of multiple complications like severe haemolytic anaemia, haemolytic jaundice, cerebral malaria and acute renal failure. This study confirms presence of severe and complicated falciparum malaria in this part of the country.

Adolescent↗

Heart disease in diabetes mellitus.

The spectrum of heart disease in diabetic patients is broad and complex. This article discusses the epidemiologic associations between the two causes. It attempts to summarize the effects of diabetes at the cellular, vascular, and myocardial levels. The clinical manifestations are explored, and the treatment of heart disease as it pertains to diabetic patients is discussed.

Adrenergic beta-Antagonists↗

Prevention of tolerance to hemodynamic effects of nitrates with concomitant use of hydralazine in patients with chronic heart failure.

OBJECTIVES: This study was designed to determine the effect of oral hydralazine on the development of nitrate tolerance in patients with chronic congestive heart failure. BACKGROUND: Early development of nitrate tolerance with either continuous administration of intravenous or topical nitrate preparations or frequent dosing of oral nitrates leads to significant attenuation of nitrate-mediated hemodynamic and anti-ischemic effects. In recent animal experiments, prevention of nitroglycerin-induced hemodynamic tolerance with a concomitant use of hydralazine was demonstrated. This finding may have important clinical relevance. METHODS: Twenty-eight patients with chronic heart failure due to left ventricular systolic dysfunction were randomized to receive either a continuous infusion (24 h) of nitroglycerin alone (group I, 14 patients) or concomitantly with oral hydralazine (75 mg four times a day [group II, 14 patients]). The effect of nitroglycerin in each group was evaluated by analysis of variance for repeated measures. The power of the analysis to detect a 5.4-mm Hg (20%) change in mean pulmonary artery wedge pressure was 90%. RESULTS: Baseline hemodynamic variables as well as the initial hemodynamic response to nitroglycerin were comparable in both groups. Compared with the initial response to nitroglycerin, a significant attenuation of effect was found in group I at 24 h in mean (+/- SE) pulmonary artery pressure (27 +/- 4% vs. 10 +/- 3%, p < 0.05) and mean pulmonary artery wedge pressure (40 +/- 4% vs. 16 +/- 4%, p < 0.05). In group II, conversely, oral hydralazine prevented nitroglycerin-induced hemodynamic tolerance and resulted in a persistent effect on mean pulmonary artery and wedge pressures throughout the study period (31 +/- 3% vs. 27 +/- 4%, p = 0.13 and 37 +/- 4% vs. 34 +/- 6%, p = 0.40, respectively). In addition, the initial effect on blood pressure was attenuated at 24 h in group I (5 +/- 2% vs. 12 +/- 3%, p < 0.05) but not in group II (15 +/- 3% vs. 17 +/- 2%, p = 0.46). CONCLUSIONS: In patients with chronic heart failure due to left ventricular systolic dysfunction, the concomitant use of oral hydralazine prevents early development of nitrate tolerance and results in a persistent nitrate-mediated hemodynamic effect on systemic and pulmonary artery and left ventricular filling pressures. These data may support the concurrent use of hydralazine in patients with heart failure treated with organic nitrates.

Administration, Oral↗

Distribution and kinetics of glucose in rats analyzed by noncompartmental and compartmental analysis.

The steady-state kinetics and distribution of glucose were assessed using noncompartmental and various two-compartment models in rats that were infused with insulin (+/- euglycemic clamping), methylprednisolone (MP), or phlorizin (PHL) as well as rats injected with protamine-zinc-insulin (PZI) or rendered diabetic. Decreases in clearance of glucose (PCR) were greatest with insulin infusion, followed by PHL, MP, and PZI treatments. PCR decreased in diabetes to 25% of normal. With hyperinsulinemia and euglycemia, turnover rates were 1.18 times the rate of glucose infusion. In normal rats the ratio of the contents of the two compartments was 0.6-0.8 (depending on the model). Significant increases, of between 2.8 and 5.2, were observed with insulin infusion and between 0.8 and 1.8 with PHL, again depending on the model. Because PHL-induced changes in PCR are renal, these data suggest that variations in glucose distribution depend on changes in PCR as well as insulin. The intercompartmental rate constant decreased, and the noncompartmental volume of distribution increased to reflect the above changes. In non-steady-state studies, glucose release increased in response to insulin but not to PHL in contrast to other species.

Animals↗

Gluconeogenesis from glycine and serine in fasted normal and diabetic rats.

1. Non-anaesthetized normal and diabetic rats were fasted for 1 day, and [U-14C]glycine, or [U-14C]serine, or [U-14C]- plus [3-3H]-glucose was injected intra-arterially. The rates of synthesis de novo/irreversible disposal for glycine, serine and glucose, as well as the contribution of carbon atoms by the amino acids to plasma glucose, were calculated from the integrals of the specific-radioactivity-versus-time curves in plasma. 2. The concentrations of both glycine and serine in blood plasma were lower in diabetic than in fasted normal animals. 3. The rates of synthesis de novo/irreversible disposal of both amino acids tended to be lower in diabetic animals, but the decrease was statistically significant only for serine (14.3 compared with 10.5 mumol/min per kg). 4. Of the carbon atoms of plasma glucose, 2.9% arose from glycine in both fasted normal and diabetic rats, whereas 4.46% of glucose carbon originated from serine in fasted normal and 6.77% in diabetic rats. 5. As judged by their specific radioactivities, plasma serine and glycine exchange carbon atoms rapidly and extensively. 6. It was concluded that the turnover of glycine remains essentially unchanged, whereas that of serine is decreased in diabetic as compared with fasted normal rats. The plasma concentration of both amino acids was lower in diabetic rats. Both glycine and serine are glucogenic. In diabetic rats the contribution of carbon atoms from glycine to glucose increases in direct proportion to the increased glucose turnover, whereas the contribution by serine becomes also proportionally higher.

Animals↗

Development and evaluation of an in vivo mouse model for studying myocutaneous flap microcirculation and viability before and after suturing or stapling.

A model was developed in albino hairless mice to study microcirculation and viability of dorsal distally based myocutaneous flaps. The efficacy of this model was tested in 120 mice by evaluating the effects of excessive crimping and tension attributed to Proximate or Signet staples or to simple or mattress nylon sutures. Microhemodynamics were assessed using computer-assisted intravital videomicroscopic and electro-optical methods. Volumetric rates of blood flow were calculated within terminal arterioles from measurements of internal diameter and mean centerline cellular velocity. The viability was determined on day 5 by measuring the areas of necrosis (mm2) along the cut edges of these flaps. In 80 mice, flaps were elevated and examined at 0 h and then again at 24 or 48 h. There were 40 mice in each of these disturbed groups. In a third group of 40 mice, flaps were raised at 0 h without videomicroscopic examination at 0, 24, or 48 h (undisturbed group). All flaps were stapled or sutured to the original donor site with one of the four methods of closure. The results of this study indicate that sutures produce the highest incidence of necrosis at 5 days when compared to staples in the undisturbed groups of mice. However, no significant differences in necrosis were observed when flaps were disturbed at 48 h despite videomicroscopic evidence of depressed blood flow along their cut edges. In contrast, results at 24 h were equivocal and statistically not significant. These data suggest that the phenomenon of delay and/or flap recirculation following removal and reapproximation of sutures or staples drastically improves perfusion and viability of disturbed flaps.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗