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Biomedical subjects

M Silverman

Publications and source records attributed to M Silverman.

At least 289 records · Page 16Linked to original sources
PubMed1986

Effects of posture and spinal bracing on respiratory function in neuromuscular disease.

Effects of posture and spinal bracing on lung function were studied in 40 children with neuromuscular disease, 20 of whom had scoliosis and were non-ambulant. Change from sitting to supine position had little effect on lung function in ambulant children, but caused a significant 12% reduction in forced vital capacity in a group of 16 non-ambulant children with scoliosis, suggesting diaphragmatic weakness in some. Spinal bracing, using a rigid supporting jacket, resulted in a significant reduction in mean vital capacity of 22%. The degree of impairment in forced vital capacity was proportional to the severity of the scoliosis (as measured by the Cobb's angle), to the amount of correction achieved by the brace, and to the degree of diaphragmatic weakness. Spinal bracing in a child with established severe scoliosis causes appreciable respiratory impairment, and this may explain why it is less likely to be tolerated than early prophylactic bracing.

Braces↗
PubMed1986

Comparison of glucose transport mechanisms at opposing surfaces of the renal proximal tubular cell.

This review contrasts the glucose transport mechanisms at opposing surfaces of the renal proximal convoluted tubule: the Na+-dependent D-glucose transporter localized at the brush border membrane and the Na+-independent transporter localized at the basolateral surface. The two sugar transport mechanisms are discussed from the point of view of their specificity, kinetic, and regulatory behaviors. Recent results focussing on molecular characterization of these different carrier proteins are also described, including some newer information on purification of the Na+-dependent glucose carrier from the brush border membrane.

Animals↗
PubMed1986

Exchange of multiple indicators across renal-like epithelia: a modeling study of six physiological regimes.

Multiple indicator dilution (MID) provides a means of quantifying the unidirectional steady-state fluxes of in vivo tracer movement within organs. In this report a MID model of tracer exchange across renal-like epithelia is developed in mathematical form. Six regimes of epithelial transport function are defined on the basis of the relative sizes of the tracer fluxes. Evidence for the existence of each regime has previously been obtained empirically. These are net secretion, net reabsorption, kinetic sink, antiluminal drive, antiluminal equilibration, and antiluminal trapping. By means of the mathematical model, the indicator dilution properties of the six regimes are compared. The principal similarities and differences among the regimes are documented and related to the physical basis of the transport processes. The findings suggest that over a wide range of physiologically meaningful flux magnitudes the functional regimes can be distinguished via existing empirical methods of MID. The model provides an improved basis for carrying out these distinctions in specific applications.

Animals↗
PubMed1986

Drug promotion: the Third World revisited.

In 1973 and 1980 surveys, much of the promotion of prescription drugs in the Third World was found to be marked by gross exaggeration of clinical claims and glossing over of possible serious or fatal adverse reactions. In an expanded survey of the information distributed in 1984 to physicians in the United States, the United Kingdom, and 28 developing nations in Africa, Asia, and Latin America, striking changes were noted. Many of the pharmaceutical firms were found to be showing more restraint in limiting their claims in the Third World to those which can be supported by scientific evidence, and far more willingness to disclose serious hazards. The companies discarding a double standard in drug promotion have apparently not suffered any significant loss of profits. There is, however, evident need for further improvement by both multinational and domestic companies. The present study covered 1069 products representing 63 drug entities and fixed combinations, marketed by 303 companies.

Africa↗
PubMed1986

Light-polymerizing plastics as slide mounting media.

Currently available mounting media require solvent evaporation for hardening. This process is slow and often is complicated by the formation of air spaces under the coverslip. Light-polymerizing plastics are introduced as histologic mounting media that eliminate these problems because they harden quickly when exposed to ultraviolet light and, therefore, do not depend upon solvent evaporation. These light-polymerizing plastics are easy to use, permit rapid and controlled hardening, and eliminate the formation of air spaces under the coverslip. The optical characteristics are satisfactory for light and fluorescence microscopy.

Animals↗
PubMed1986

Cellular mechanisms of digoxin transport and toxic interactions in the kidney.

Renal tubular secretion of digoxin appears to be one of the main ports of elimination of the glycoside from the body. Because of its narrow therapeutic window and severe toxicity, the mechanisms of tubular handling of digoxin are important. Moreover, several drugs which are commonly administered with digoxin, including quinidine, spironolactone, verapamil and amiodarone have been shown to decrease renal clearance of digoxin without affecting GFR. We studied the handling of digoxin using in vitro and in vivo approaches. The handling of the glycoside by the brush border suggests passive reabsorption which is not enhanced by commonly coadministered drugs. Digoxin binding to the antiluminal (basal) membrane suggests that the secretion of the glycoside may not involve the pharmacologic receptor, the Na+, K+, ATPase. Using the multiple indicator dilution technique, we could directly show the two steps of secretion of digoxin: Its sequestration from the postglomerular circulation, and its appearance in the urine after transtubular transport. Digoxin transport is not inhibited by a cationic or anionic molecule (PAH and tolazoline). It is possible that digoxin is secreted by a yet unidentified transport mechanism.

Animals↗
PubMed1985

Predictive value of cranial ultrasound in the newborn baby: a reappraisal.

During a 36-month period 435 babies of 34 weeks' gestation or less were regularly scanned with ultrasound. A large periventricular/intraventricular haemorrhage developed in 40 babies, and extensive cystic leucomalacia developed in 10. The neurodevelopmental outcome and the frequency of handicap in these 2 groups were compared. 9 of the 18 survivors with a large haemorrhage were found to be completely normal and only 2 showed a major handicap. However, severe cerebral palsy with mental retardation developed in all the survivors with extensive cystic leucomalacia, and 4 of the 7 babies were also cortically blind. These findings suggest that the size of the haemorrhage is not a good predictor of outcome, but that severe cystic leucomalacia is associated with a very poor prognosis.

Brain↗
PubMed1985

Measuring gene expression with light.

Light is produced by recombinant Escherichia coli that contain lux genes cloned from the marine bacterium Vibrio fischeri. The bioluminescence phenotype requires genes for regulatory and biochemical functions, the latter encoded by five lux genes contained in a single operon. These lux genes were disconnected from their native promoter and inserted into the transposon mini-Mu. The resulting transposon, mini-Mulux, could induce mutations by insertional inactivation of a target gene, and the lux DNA was oriented to align target gene transcription with that of the lux genes. Genes in Escherichia coli and Vibrio parahaemolyticus were mutagenized, and mutants containing transposon-generated lux gene fusions produced light as a function of target gene transcription. Light production offers a simple, sensitive, in vivo indicator of gene expression.

DNA Transposable Elements↗
PubMed1985

Psychiatric consultation to elderly medical and surgical inpatients in a general hospital.

The elderly (65 years or older) constitute approximately 25% of the patients referred for psychiatric consultations in general hospitals. The authors compared the clinical characteristics of and treatment recommendations for elderly and younger (less than 65 years) patients. Our findings revealed fourteen distinctive characteristics which differentiated the elderly from the younger patients. Most notably, the elderly have had a longer hospitalization at the time of the request for a psychiatric consultation and had a higher prevalence of organic brain syndromes (O.B.S.). Some of the implications of these results are discussed with the view to planning psychiatric services for the elderly in general hospitals.

Aged↗
PubMed1985

Single-breath measurement of lung mechanics in very low birth weight infants.

The expiratory time constant of the respiratory system (Trs) and the total respiratory system compliance (Crs) were measured from the analysis of a flow-volume loop during relaxed expiration, and the total respiratory system resistance (Rrs) was derived from the relationship: Rrs = Trs/Crs. In ten intubated and mechanically ventilated very low birth weight infants, the values obtained for compliance (0.21 to 0.71 ml/cm H2O) were similar to those found using an occlusion technique during spontaneous breathing. The values of Trs were 0.03 to 0.14 sec. These Trs values were altered by adding known resistive loads. The corresponding derived values for Rrs were close to the values of the added resistance loads, suggesting that resistance values found in this group of ventilated babies (120 to 380 cm H2O/L X sec) were accurate.

Humans↗
PubMed1985

Gastro-oesophageal reflux and childhood asthma: the acid test.

The presence of gastro-oesophageal reflux was investigated in 18 children with moderate to severe asthma by overnight oesophageal pH monitoring. Appreciable reflux was found during sleep in eight; its relevance to nocturnal asthma was not clear. On another occasion the same children were challenged in a double blind fashion with a drink of dilute hydrochloric acid (0.001 N) and the response of the airways was monitored by peak flow measurements and by histamine challenge tests. There was a significant increase in mean histamine sensitivity (p = 0.001) 90 minutes after the acid drink without any associated change in baseline peak flow rate. Eight children had a significant response to the acid drink, and a further three reacted to a more concentrated solution (0.01 N). In those asthmatic children in whom reflux is associated with a positive response to an acid drink (five out of 18 in the present study) it seems likely that reflux exacerbates nocturnal symptoms.

Adolescent↗
PubMed1985

Sugar uptake into a primary culture of dog kidney proximal tubular cells.

We describe the functional characteristics of a new primary culture system derived from a suspension of dog proximal tubular cells. The culture system is maintained on alpha minimal essential medium with 15% fetal calf serum supplementation. At confluency the cultured cells demonstrate the following: (i) typical epithelial morphology using light microscopy, with multiple dome formation inhibited by ouabain; (ii) strong binding with a polyclonal antibody directed against dog proximal tubular brush border membrane antigens; (iii) high concentration of alkaline phosphatase activity by histochemical staining; and (iv) 25-hydroxycholecalciferol (25(OH)D3)-24-hydroxylase activity. Sugar transport was assessed using alpha-methyl-D-glucopyranoside (alpha MG), a nonmetabolizable analog of D-glucose, as well as L-glucose, and 3-O-methyl-D-glucose (3OMG). The transport of alpha MG was stereospecific; temperature sensitive; inhibited strongly by phlorizin but not by cytochalasin B, phloretin, or 3OMG; and Na dependent. The transport of 3OMG is stereospecific, temperature sensitive, and inhibited strongly by phloretin and cytochalasin B, but not by phlorizin. Despite the apparent heterogeneity of cell type, this primary culture system exhibits many features of normal dog proximal tubule function.

Alkaline Phosphatase↗