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Biomedical subjects

M Silverman

Publications and source records attributed to M Silverman.

At least 325 records · Page 18Linked to original sources
PubMed1983

The natural history of carotid plaque development.

Fifty-seven carotid artery plaques in 54 patients were harvested at surgery and studied. Preoperative noninvasive findings, arteriograms, clinical symptoms, surgical findings, and light microscopic findings were compared. Thirty-four patients had symptoms, 28 with TIAs and six with a previous stroke. Thirty-three of the 34 had intraplaque hemorrhage, and 28 had a connection between the hemorrhage and the arterial lumen. Eleven of the 21 asymptomatic patients also had an intraplaque hemorrhage, and one had a connection. In eight of the 11, noninvasive studies showed progression of disease. The development of an intraplaque hemorrhage appears to be an important factor in an innocent plaque's becoming a clinically relevant one. If a connection develops between the intraplaque hemorrhage and the arterial lumen, the patient may have TIAs.

Aged↗
PubMed1983

Bacterial bioluminescence: isolation and genetic analysis of functions from Vibrio fischeri.

Recombinant E. coli that produce light were found in a clone library of hybrid plasmids containing DNA from the marine bacterium Vibrio fischeri. All luminescent clones had a 16 kb insert that encoded enzymatic activities for the light reaction as well as regulatory functions necessary for expression of the luminescence phenotype (Lux). Mutants generated by transposons Tn5 and mini-Mu were used to define Lux functions and to determine the genetic organization of the lux region. Regulatory and enzymatic functions were assigned to regions of two lux operons. With transcriptional fusions between the lacZ gene or transposon mini-Mu and the target gene, expression of lux operons could be measured in the absence of light production. The direction of transcription of lux operons was deduced from the orientation of mini-Mu insertions in the fusion plasmids. Induction of transcription of one lux operon required a function encoded by that operon (autoregulation). From these and other regulatory relationships, we propose a model for genetic control of light production.

Cloning, Molecular↗
PubMed1983

Utilization pattern of a Canadian psychiatric consultation service.

The authors reviewed 255 psychiatric consultations in a Canadian teaching general hospital over a one-year period. The majority of the patients were referred from the medical and surgical services. The three most commonly stated reasons for referral were either parasuicidal behavior, depression, or psychological conflicts affecting physical illness. The three most common primary psychiatric diagnoses were: affective disorders, organic brain syndromes, and transient situational disturbances. The factors influencing compliance among the patients referred for psychiatric ambulatory treatment were studied. Compliance was defined as attendance at the first appointment. Of the 42.8% of the patients referred for ambulatory psychiatric treatment, 54% complied.

Adult↗
PubMed1983

Postural variations in pulmonary resistance, dynamic compliance, and esophageal pressure in neonates.

In order to determine effect of posture and to assess the reliability of the esophageal balloon method for measuring esophageal pressure changes (delta Pes) under clinical conditions, lung mechanics were measured in 13 term and preterm babies in each of 3 postures: supine, right, and left lateral. The pulmonary resistance (Rp) was significantly lower and the dynamic compliance (Cdyn) higher in the right lateral than in the supine position. Judged by the occlusion test, delta Pes was recorded accurately in each posture. The mean end-expiratory esophageal balloon pressure (PesEE) was higher in preterm infants and in the supine posture. It is concluded that the (right) lateral posture is mechanically less demanding than the supine posture and that delta Pes can be measured accurately in the supine posture. Absolute values of PesEE have no physiologic meaning and should not be used for patient management or for the calculation of lung mechanics.

Airway Resistance↗
PubMed1983

Endotoxaemia in cystic fibrosis: response to antibiotics.

In a study of 6 children with cystic fibrosis receiving intravenous antibiotics for pseudomonas lung infection, serum endotoxin values were monitored by a modification of the limulus lysate technique. The values fell with treatment, reflecting a response that was not always apparent on clinical assessment. Endotoxin concentrations may offer a more precise way of monitoring the effects of antibiotic treatment in CF patients.

Adolescent↗
PubMed1983

Selective placement of bronchial suction catheters in intubated neonates.

Flexible suction catheters were passed through the endotracheal tubes of infants undergoing mechanical ventilation, just before chest radiographic examination for clinical purposes. With the head straight, 7 of 10 straight catheters entered the right main bronchus but with the head turned, 17 of 20 straight catheters and 19 of 20 curved tip catheters entered the contralateral bronchus.

Catheterization↗
PubMed1983

Pulmonary compliance in sick low birthweight infants. How reliable is the measurement of oesophageal pressure?

Measurements of dynamic lung compliance (Cdyn) were made on 42 occasions in a group of 15 intubated very low birthweight infants with respiratory distress syndrome, using an oesophageal balloon and pneumotachograph system. Values of Cdyn were compared with those of total respiratory system compliance (Crs) using an occlusion technique. Ten very low birthweight infants with no respiratory disease were similarly studied while breathing through a facemask. The occlusion tests for oesophageal balloon assessment were unsatisfactory in 14 of 15 intubated infants, but in only 3 of the 10 normal infants. Values of Cdyn were poorly reproducible and correlated poorly with Crs. We conclude that in sick intubated preterm infants oesophageal pressure (and hence Cdyn) cannot be reliably measured, but that Crs may be a useful parameter of lung stiffness.

Esophagus↗
PubMed1983

Indomethacin treatment for patent ductus arteriosus in very low birthweight infants: double blind trial.

Thirty very low birthweight (VLBW) infants (mean gestational age 28.9 weeks; mean birthweight 1138 g) with symptomatic patent ductus arteriosus (PDA) were entered in a randomised double blind trial of indomethacin treatment. The mean age at diagnosis was 7.6 days and at entry to the trial 10.7 days. Before treatment for PDA the indomethacin and placebo groups were well matched for gestational age, birthweight, incidence of respiratory distress requiring mechanical ventilation, and fluid intake. Treatment was up to three daily doses of indomethacin 0.2 mg/kg or placebo by gastric tube and fluid restriction. During treatment there was a response in 13 out of 15 in the indomethacin group and in 3 out of 15 in the control group (P less than 0.001), but because of relapse the effect was maintained in only 7 out of 15 and 2 out of 15 respectively (P less than 0.05). No abnormalities were attributable to indomethacin, which is a safe and effective treatment for PDA in the VLBW infant, but the high relapse rate despite fluid restriction suggests that the best treatment has still to be found.

Clinical Trials as Topic↗
PubMed1983

Reproducibility of histamine challenge tests in asthmatic children.

The measurement of bronchial reactivity by histamine challenge testing is of increasing clinical importance in paediatrics. By means of a simple tidal breathing technique for the measurement of histamine sensitivity (expressed as PC20--the concentration of histamine which produces a 20% fall in peak flow rate) in childhood asthma, the reproducibility of pairs of tests was estimated over one hour and 24-hour intervals in 22 children. Under carefully controlled conditions the 95% confidence limits of PC20 were 0.8-1.25 X baseline PC20 after one hour and 0.36-2.8 X baseline PC20 after 24 hours.

Adolescent↗
PubMed1983

Determination of glomerular permselectivity to neutral dextrans in the dog.

The multiple-indicator-dilution (MID) technique was used to separate solute flux (Js) across the glomerular and postglomerular capillaries in vivo. Anesthetized mongrel dogs (n = 20) during mannitol diuresis received a pulse of extracellular indicators including 125I-albumin (plasma reference), [14C]inulin (glomerular reference), creatinine (interstitial reference), and a neutral [3H]dextran (specific mol wt between 10,000 and 24,000 dalton) in the left renal artery. Left renal venous and ureteric outflows were rapidly sampled. 3H-labeled dextrans 10,000-15,500 had renal vein mean transit times (t) greater than those of 125I-albumin, indicating postglomerular extraction. 3H-labeled dextrans greater than 15,500 had t values identical to those of 125I-albumin, indicating only unidirectional glomerular extraction. The glomerular fractional dextran extractions relative to simultaneously injected [14C]inulin (ED/Ei) were calculated from urine and renal vein outflow curves and ranged from 0.98 +/- 0.02 to 0.33 +/- 0.12 (SD) for mol wt 10,000 +/- 24,000. ED/Ei values were quantitatively identical to constant-infusion fractional clearances of the same dextrans. Renal plasma flow (RPF) was then deliberately reduced two-to threefold in the same dog. ED/Ei as measured by the MID technique remained unchanged during graded reduction in RPF. In constant-infusion experiments RPF was reduced from 5.78 to 2.77 ml X s-1 X 100 g-1 and GFR from 50.4 to 36.3 ml X min-1, but the fractional neutral dextran clearances remained constant. The predominance of convective solute flux across the dog glomerulus permitted calculation of glomerular reflection coefficients 0.03 +/- 0.06 to 0.85 +/- 0.03 (SD) for neutral 3H-labeled dextrans 10,000-24,000 dalton.

Animals↗
PubMed1983

Determination of postglomerular permselectivity to neutral dextrans in the dog.

The single-pass multiple-indicator-dilution (MID) technique was used to analyze postglomerular capillary permeability. Anesthetized mongrel dogs (n = 13) during mannitol diuresis received a pulse injection of 125I-albumin (plasma reference), [14C]inulin (glomerular reference), creatinine (interstitial reference), and a homogeneous [3H]dextran molecular weight marker 6,000-12,000 dalton in the left renal artery. Simultaneous left renal venous outflow and right and left urine were rapidly sampled. Left urine recoveries of creatinine, [14C]inulin, and [3H]dextran were identical, indicating no glomerular solute flux limitation. Progressive precession of the [14C]inulin and [3H]dextran renal vein curves relative to creatinine indicated increasing postglomerular limitation to solute flux proportional to molecular size. The postglomerular solute extraction (EPG) (renal vein upslope indicator/125I-albumin) varied inversely with postglomerular renal plasma flow (F), indicating diffusion limitation. Ouabain infusion into the left renal artery significantly reduced Na reabsorption but did not alter the EPG of [14C]inulin or [3H]dextran. Permeability-surface (PS) area products calculated from EPG and F ranged from 4.86 +/- 0.89 to 0.97 +/- 0.25 (SD) cm X s-1 X 100 g-1 for indicators 5,000-12,000 dalton. [14C]Inulin PS products remained constant for F greater than or equal to 2.50 ml X s-1 X 100 g kidney-1. PS[3H]dextran/PS[14C]In (n = 20, F greater than or equal to 2.5 ml X s-1) was used to calculate an effective postglomerular capillary pore radius, r = 55.5 +/- 7.6 (SD) A.

Animals↗
PubMed1983

Esophageal pressure in infants at elevated lung volumes and positive airway pressure.

The measurement of esophageal pressure changes (delta Pes) under conditions of elevated lung volume or continuous positive airway pressure (CPAP) was investigated in a group of 17 infants by use of an esophageal balloon. Eleven of the infants were studied in a whole-body plethysmograph, and lung volume was increased by a volume injection technique. Reproducible measurements of lung volume in the plethysmograph showed that changes in mask pressure (delta Pm) were accurate during airway occlusion in 10 of the 11 infants. A progressive elevation of the ratio delta Pes/delta Pm during respiratory efforts against occlusion at lung volumes above the tidal range was observed in 8 of the 11 infants. In only one of these infants could the error have been in delta Pm measurement. Of seven infants (including one common to both studies) studied under CPAP, six also showed this effect, which occurred predominantly in very young or preterm infants. Changes in esophageal pressure in infancy, measured at high lung volumes or pressures, may not be representative of mean pleural pressure changes.

Esophagus↗
PubMed1982

Bacterial bioluminescence: isolation and expression of the luciferase genes from Vibrio harveyi.

Genes for the luciferase enzyme of Vibrio harveyi were isolated in Escherichia coli by a general method in which nonluminous, transposon insertion mutants were used. Conditions necessary for light production in E. coli were examined. Stimulation of transcription of the genes for luciferase (lux A and lux B) was required for efficient synethesis of luciferase. To enhance transcription bacteriophage promoter elements were coupled to the cloned lux gene fragments.

Escherichia coli↗
PubMed1982

Treatment of methanol poisoning with ethanol and hemodialysis.

Twelve cases of methanol poisoning are reviewed. The clinical presentation and biochemical features are described and the results of treatment with alkali, ethanol and dialysis reported. The outcome of methanol poisoning appears to be related more to the interval between the time of ingestion and the start of therapy and to the degree of acidosis than to the initial serum methanol level. Therefore, early and aggressive treatment with bicarbonate and ethanol and subsequent institution of hemodialysis are strongly recommended whenever methanol can be detected in the blood, especially when metabolic acidosis of the anion-gap type is present, when mental or visual disturbances are present, or when more than 30 ml of absolute methanol has been consumed.

Acidosis↗
PubMed1982

Controlled trial of slow-release aminophylline in childhood asthma: are short-term trials valid?

Slow-release aminophylline, although widely used for the prophylaxis of childhood asthma, has had only limited formal assessment. A four-month double-blind cross-over trial of slow-release aminophylline (14 mg/kg twice daily) was carried out in 24 children with perennial asthma. Satisfactory serum theophylline concentrations were obtained in 17 children, with few side effects. There was a significant improvement in mild daytime and night-time symptoms. The incidence of more severe symptoms was unaffected. Treatment did not improve the mean peak expiratory flow or reduce the incidence of use of bronchodilators. It is concluded that slow-release aminophylline has a place in the prophylaxis of perennial childhood asthma but is unsuitable for children who suffer from severe attacks. The cross-over trial design has severe limitations.

Adolescent↗