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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 703 records · Page 39Linked to original sources
PubMed1986

Health significance and occurrence of injured bacteria in drinking water.

Enteropathogenic and indicator bacteria become injured in drinking water with exposure to sublethal levels of various biological, chemical and physical factors. One manifestation of this injury is the inability to grow and form colonies on selective media containing surfactants. The resulting underestimation of indicator bacteria can lead to a false estimation of water potability. m-T7 medium was developed specifically for the recovery of injured coliforms (both "total" and fecal) in drinking water. The m-T7 method was used to survey operating drinking water treatment and distribution systems for the presence of injured coliforms that were undetected with currently used media. The mean recovery with m-Endo LES medium was less than 1/100 ml while it ranged between 6 and 68/100ml with m-T7 agar. The majority of samples giving positive results with m-T7 medium yielded no detectable coliforms with m-Endo LES agar. Over 95% of the coliform bacteria in these samples were injured. Laboratory experiments were also done to ascribe the virulence of injured waterborne pathogens. Enteropathogens including Salmonella typhimurium, Yersinia enterocolitica and Shigella spp. required up to 20 times the chlorine levels to produce the same injury in enterotoxigenic Escherichia coli (ETEC) and nonpathogenic coliforms. Similar results were seen with Y. enterocolitica exposed to copper. The recovery of ETEC was followed by delayed enterotoxin production, both in vitro and in the gut of experimental animals. This indicates that injured waterborne enteropathogenic bacteria can be virulent.

Chlorine↗
PubMed1986

Effect of beta-blockade on right ventricular performance in patients with and without right ventricular dysfunction due to coronary artery disease.

To assess the effects of beta-blockade on right ventricular performance in patients with and without right ventricular dysfunction due to coronary artery disease, we performed radionuclide ventriculography on eight patients with normal right ventricular ejection fraction (RVEF greater than or equal to 35%) and 14 patients with mild to moderate right ventricular dysfunction (RVEF less than 35%) at rest. All patients had chronic stable angina pectoris, and nine patients had prior myocardial infarction. Radionuclide ventriculography was performed on placebo and during clinical beta-blockade (heart rate, 50 to 60 beats per minute and less than or equal to 20% increase in heart rate over baseline during stage I treadmill exercise, Bruce protocol) with the oral, cardioselective beta-blocking agent, betaxolol. The resting RVEF (mean +/- 1 SD) was 33% +/- 7% on placebo and 34% +/- 7% during clinical beta-blockade. Mean exercise RVEF was 40% +/- 8% on placebo and 39% +/- 8% during clinical beta-blockade. These differences were not statistically significant. Resting left ventricular ejection fraction ranged from 22% to 60% (mean, 42% +/- 8%). On placebo, one of eight patients with a resting RVEF greater than or equal to 35% had a normal exercise RVEF response (greater than or equal to 5% increment) whereas nine of 14 patients with resting RVEF less than 35% had normal exercise response. The discordant relationship between baseline RVEF and exercise response on placebo became less marked during clinical beta-blockade. We conclude that beta-blockade does not produce significant deterioration of right ventricular systolic function or right ventricular reserve either in patients with normal or in those with mild to moderately impaired resting right ventricular systolic function.

Adrenergic beta-Antagonists↗
PubMed1986

Cholestasis and fatal agranulocytosis complicating sulfasalazine therapy: case report and review of the literature.

A 55-year-old woman with rheumatoid arthritis in overlap with polymyositis received sulfasalazine for control of synovitis. Cholestatic jaundice, fever, urticaria and agranulocytosis developed after 20 days of treatment and culminated in fatal adult respiratory distress syndrome secondary to Legionella pneumophila. The increasing use of sulfasalazine in the therapy of rheumatoid arthritis mandates that the clinician be aware of this idiosyncratic drug reaction.

Agranulocytosis↗
PubMed1986

Nutritional intakes and status of highly trained amenorrheic and eumenorrheic women runners.

This study was conducted to determine whether nutritional status contributes to the amenorrhea associated with long distance running. Dietary intakes and biochemical measures of nutritional status were compared in highly trained amenorrheic (AM) and eumenorrheic (EU) women runners matched for height, weight, percent fat (11% to 12%) and training distance (113 km/week). Serum estradiol (E2) (EU, 104.7 pg/ml, versus AM, 22.5 pg/ml) and cortisol (EU, 22.4 micrograms/dl, versus AM, 26.6 micrograms/dl) concentrations differed between the two groups. Three-day dietary records revealed that fat intake by AM runners was significantly lower than by EU runners (EU, 97 gm/day, versus AM, 66 gm/day). AM runners consumed large amounts of vitamin A activity, probably in the form of B-carotene, and fairly high quantities of crude fiber. Zinc intake by AM runners was well below the recommended dietary allowances (RDA), compared with EU runners (EU, 15.4 mg, versus AM, 10.9 mg). Further, plasma zinc tended to be lower for the AM runners (EU, 85.7 micrograms/dl, versus AM, 81.2 micrograms/dl). It was concluded that the potential contributions of dietary fat, B-carotene, and zinc to inducing changes in menstrual function and the metabolism of certain hormones should be investigated.

Adult↗
PubMed1986

Samoyed hereditary glomerulopathy (SHG). Evolution of splitting of glomerular capillary basement membranes.

Samoyed hereditary glomerulopathy (SHG) in dogs resembles hereditary nephritis (HN) in man. Affected males and carrier females spontaneously develop proteinuria, but only males progress to renal failure. We examined the evolution of splitting of glomerular capillary basement membranes (GCBM) in affected male and carrier female dogs. At birth, examination by light microscopy (LM) in all dogs showed normal glomerular capillaries, but by electron microscopy (EM), many GCBM showed separation of endothelial from visceral epithelial cell basement membranes. By LM, glomerular capillaries of affected males appeared normal for up to 4 months, but then isolated and eventually all capillaries became thickened and split. However, by EM, a bilaminar appearance of the GCBM was seen within 1 month which evolved into multilaminar splitting that became extensive as renal failure ensued. Carrier females showed mild nonprogressive changes in GCBM. These results with SHG permitted speculation on the evolution of splitting of GCBM in human HN.

Animals↗
PubMed1985

Abscess of the thyroid gland presenting as a pulsatile mass.

Thyroid abscess is a rare disorder, particularly since the advent of antibiotic agents. A case of thyroid abscess, which developed without systemic disturbance, and presented as a pulsatile mass in the neck, is reported. Excision with primary closure was followed by uncomplicated recovery, and is suggested as the preferred form of management.

Abscess↗
PubMed1985

Intravenous KCl supplementation in pediatric cardiac surgical patients.

A total of 31 pediatric cardiac patients (mean age 19 1/2 months) who required surgery for repair of various congenital heart defects were prospectively studied in the postoperative period to determine potassium (K) dose-response characteristics. All patients received supplementary K when the serum K was less than 4.0 meq/liter. A total of 100 administrations of intravenous potassium chloride (KCl) were evaluated. KCl, 0.5 meq/kg, was infused over 2 h by syringe pump. This infusion was repeated as necessary to achieve a serum K greater than or equal to 4.0 meq/liter. The KCl was administered in addition to the K in the patients' maintenance solution. Blood samples for serum K determination were collected 15-30 min before and after the KCl infusion. The mean K dose administered was 0.72 +/- 0.23 meq/kg. This produced a mean rise in serum K of 0.61 +/- 0.48 meq/liter. Of 100 administrations, 11 resulted in no change or a decrease in serum K. Four of 100 administrations resulted in serum K greater than 5.0 meq/liter. Intravenous KCl supplementation in a dose of 0.5 meq/kg administered over 2 h is safe and effective for pediatric postoperative cardiac patients. Serum K should be measured to monitor therapy, due to variable response.

Adolescent↗
PubMed1985

Rapid resolution of perfusion/ventilatory abnormalities in pulmonary air embolism.

A case of pulmonary air embolism is presented demonstrating a nearly total lung perfusion defect and a matching ventilation deficit. Despite advanced age, mild chronic obstructive airway disease, and congestive heart failure, the perfusion/ventilatory (V/Q) abnormalities produced by the air emboli resolved to near completion within three days. Rapid resolution of V/Q abnormalities due to air embolism is distinct when compared to the abnormalities seen with thromboembolism and the mechanism the matching V/Q defects is discussed.

Aged↗
PubMed1985

Responses of opsonic substances to major trauma and sepsis.

Adequate opsonic capability is vital for normal host defense against infection. The presence of complement fraction 3 (C3) indicates both classical and alternative pathways of complement activation, while complement fraction 4 (C4) indicates only classical pathway activation. C-reactive protein (CRP) functions as an opsonic substance. We measured serum levels of C3, C4, and CRP in 32 trauma patients. Six suffered minor injuries and 26 suffered major injuries. Nineteen of the major-injury patients developed post-trauma sepsis. Complement levels fell immediately after injury and remained low for approximately 8 days in all patients. CRP levels rose by 12 h, peaked at 48 h, and correlated with the severity of injury and the presence of sepsis. Elevated CRP levels after 4 days postinjury indicated the presence of sepsis in all cases. CRP elevations preceded clinical diagnosis by an average of 2.4 days. Serial measurements of CRP are valuable in monitoring the course of trauma patients and may indicate the presence of septic complications before clinical detection.

C-Reactive Protein↗
PubMed1985

Reduced virulence of Yersinia enterocolitica by copper-induced injury.

A sublethal concentration of copper (0.75 mg/liter) caused substantial injury (87 to 95%) of Yersinia enterocolitica serotype O:8 cells in 72 h at 4 degrees C without producing extensive cell death. Copper-injured cells had a higher 50% lethal dose in mice (2,700 CFU) than uninjured cells (150 CFU). This reduced virulence correlated with more rapid clearance of the injured cells from the blood of mice after intravenous inoculation. A possible role of the liver in this process was shown by significant cell accumulation in mouse livers when copper-injured Y. enterocolitica cells were administered, compared with uninjured bacteria. In vitro studies with isolated mouse liver membranes showed higher titers of aggregation with copper-injured cells than control cells. The in vitro aggregation reaction and blood clearance activity in vivo were abolished by sugars that are known to interact with a hepatic lectin. Our data suggest that copper-induced injury reduces the virulence of Y. enterocolitica and that the liver may be involved in nonimmune rapid clearance of the injured cells, probably by interaction with a hepatic lectin(s).

Animals↗
PubMed1985

Changes in virulence of waterborne enteropathogens with chlorine injury.

We designed experiments to assess the effect of chlorine injury on the virulence of waterborne enteropathogens. Higher chlorine doses (0.9 to 1.5 mg/liter) were necessary to produce injured Yersinia enterocolitica, Salmonella typhimurium, and Shigella spp. than to produce injured enterotoxigenic Escherichia coli or coliform bacteria (0.25 to 0.5 mg/liter) in the test system used; 50% lethal dose experiments in which mice were used showed that injured Y. enterocolitica cells were 20 times less virulent than uninjured control cells (3,300 and 160 CFU, respectively). This decrease in virulence was not related to reduced attachment to Henle 407 intestinal epithelial cells, but could be related to a loss of HeLa cell invasiveness. In contrast, injured S. typhimurium and enterotoxigenic E. coli cells lost their ability to attach to Henle cells. These data show that some enteropathogens and coliform bacteria differ in their sensitivities to chlorine injury and that the virulence determinants affected by chlorine may vary from one pathogen to another.

Animals↗
PubMed1985

Spontaneous recanalisation of side branches occluded during percutaneous transluminal coronary angioplasty.

Percutaneous transluminal coronary angioplasty was performed in a 56 year old man with postinfarction angina. During an otherwise uncomplicated dilatation of a left anterior descending artery with a 70% stenosis two diagonal branches, each measuring 1.5 mm in diameter, were occluded. The occlusions were not associated with any adverse clinical effects, though there was a small rise in plasma creatine kinase concentration. The patient became free of angina two weeks after angioplasty, and follow up angiography showed spontaneous reappearance of the occluded side branches. Redistribution of atheromatous material and its later reabsorption may have been the mechanism for the initial occlusion and later reappearance of the vessels.

Angioplasty, Balloon↗