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Biomedical subjects

M Silverman

Publications and source records attributed to M Silverman.

At least 181 records · Page 10Linked to original sources
PubMed1992

Increased levels of bronchoalveolar lavage fluid interleukin-6 in preterm ventilated infants after prolonged rupture of membranes.

This study investigated the effect of prolonged rupture of the amniotic membranes (PROM) and probable maternal or fetal sepsis without PROM on the newborn preterm airway. Bronchoalveolar lavage fluid (BALF) was obtained from 38 infants in the first day of life and analyzed for number of white cells and concentration of interleukin-6 (IL-6). The volume of lung epithelial lining fluid (ELF) was estimated using the urea dilution technique. Infants with PROM (n = 13) and those with sepsis (n = 8) had higher total numbers of white cells in BALF compared with infants without PROM or sepsis (n = 17) (55 and 44 versus 7 x 10(4) white cells, p less than 0.01). Uncorrected and urea-corrected IL-6 concentrations were also higher in the two groups (18.5 and 30.8 versus 5.0 fmol/ml BALF, p less than 0.01; 157.7 and 444 versus 88.5 fmol/ml ELF, p less than 0.05). There was a significant correlation between BALF white cells and uncorrected IL-6 concentrations (rs = 0.78, p less than 0.0001). Detectable serum C-reactive protein in newborn infants was associated with increased levels of IL-6 in BALF (42.2 versus 11.8 fmol/ml BALF, p less than 0.05). We conclude that PROM is associated with airway inflammation and raised levels of IL-6 in neonatal lung fluid within the first 24 h of life and that this may initiate a systemic stress response.

Bacterial Infections↗
PubMed1992

'Not waving but drowning': psychiatric inpatient services in East Lambeth 1990.

This paper presents the results of the latest in a series of surveys of an inner-city public psychiatric inpatient service. Severe pressures on the service had led to the purchase of inpatient beds in the private hospital sector and intensive care facilities in a large psychiatric hospital. On a census day the nominal occupancy for the inpatient unit was 117%. Implications of the survey, trends over time and possible solutions to the difficulties of the inpatient unit are discussed.

Adolescent↗
PubMed1992

Rat glomerular epithelial cells in culture express characteristics of parietal, not visceral, epithelium.

Glomerular epithelial cells (GEC) in culture are derived from intact isolated glomeruli. Although there is general agreement about distinguishing GEC from mesangial and endothelial cells, there is still uncertainty regarding the visceral versus parietal origin of cultured GEC. If these cells are to provide a useful model system, it is necessary to establish well-defined cell populations. The purpose of this study was to evaluate this important issue by comparing the characteristics of cultured GEC with glomerular epithelium from rat kidney sections. By electron microscopy, GEC were polygonal, with cilia and desmosomes between cells, similar to parietal cells in situ. Because intermediate filaments are specifically expressed in differentiated cells in the kidney, the expression of intermediate filaments in cultured GEC were compared with those of intact glomeruli. Cultured GEC are positive for cytokeratin and negative for vimentin and desmin, identical to parietal cells in situ. In contrast, podocytes are positive for vimentin and desmin and negative for cytokeratin. In vivo, podocytes express gp330 and puromycin-aminonucleoside (PAN) susceptibility, which are used as markers for cultured GEC. Immunoperoxidase staining of rat kidney sections with monoclonal anti-gp330 demonstrated gp330 localization to the cell surface and coated pits of the parietal cells, similar to its localization in podocytes. The presence of gp330 in cultured GEC was confirmed by immunoblot. PAN administration to rats induced vacuolization and detachment from the basement membrane in the parietal cells of Bowman's capsule, similar to the cytotoxicity observed in podocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Fractional processing of sequential bronchoalveolar lavage fluid from intubated babies.

Two groups of intubated newborn babies were studied to determine the clinical effects of interrupted bronchoalveolar lavage (BAL) by suction catheter (S-BAL) and the similarities to adult fibreoptic BAL of fractional processing of sequential lavage fluid (BALF). Both groups were lavaged by two aliquots of 1 ml.kg-1, instilled via a blindly placed suction catheter, wedged on two separate insertions through the right main bronchus. In 14 infants, (sequential lavage group), BALF aliquots were analysed separately. There were no differences in the volumes recovered or total cell counts between the first and second BALF aliquots. Where cell morphology was visible (n = 11), the percentage of macrophages, but not the absolute number, increased in the second BALF aliquot (p less than 0.01). BALF urea and epithelial lining fluid volume estimated by urea dilution were similar between the two aliquots (n = 8). In a separate group (blood gas group), vital signs were recorded in 10 infants undergoing S-BAL. At 1 min after lavage there was a rise in mean arterial blood pressure (39 vs 49.5 mmHg, p less than 0.05) and a fall in transcutaneous oxygenation (10.6 vs 7.5 kPa, p less than 0.05). Recovery was present at 3 min post-S-BAL, but mean blood pressure remained elevated (39 vs 45 mmHg, p less than 0.05) and transcutaneous oxygen continued to be lower when compared to baseline values (10.6 vs 9.2 kPa, p less than 0.05). S-BAL of intubated infants appears to sample both the proximal and distal airways and results in changes in vital signs similar to routine non-selective endotracheal suctioning.

Blood Gas Analysis↗
PubMed1991

Neutrophil apoptosis and clearance from neonatal lungs.

8 newborn babies with airways inflammation, who were mechanically ventilated, underwent bronchoalveolar lavage to examine the fate of neutrophils in the inflamed airways. Light microscopy and electronmicroscopy showed evidence of neutrophil apoptosis and ingestion of intact neutrophils by macrophages in specimens from all 8 infants. Neutrophil apoptosis, without the local release of intracellular contents that promote inflammation, might represent a mechanism by which tissue injury is reduced during the resolution of neonatal pulmonary inflammation.

Bronchoalveolar Lavage Fluid↗
PubMed1991

Aerosol delivery in neonatal ventilator circuits: a rabbit lung model.

The benefits of inhaled therapy in ventilated neonates are recognized, but the reliability of drug delivery in nebulizer-ventilator circuits is uncertain. We quantified the effect of changing variables. Twenty-three freshly killed rabbits (1.15-1.9 kg) were ventilated via a tracheostomy by a pressure-limited, time-cycled ventilator (Neovent). A radioaerosol of 99Tcm pertechnetate from an Ultravent nebulizer (Mallinkrodt) was fed into the proximal ventilator tubing. Two 3-minute nebulizations at "standard settings" were followed by 2 at altered pressure, frequency, gas flow, I:E ratio, or position of the nebulizer in the circuit. Each nebulization was followed by a 3-minute gamma camera image and total deposited radioactivity was measured in excised lungs and trachea. Images demonstrated good peripheral aerosol deposition. At standard settings, lung deposition averaged 2.8% of the aerosol released. This was decreased markedly by reducing tidal volume (ventilator pressures) and residence time of aerosol (I:E ratio). Reduced gas flow decreased deposition slightly, presumably by increased particle size and marginally reduced tidal volume. Deposition did not change with increased frequency; increased minute ventilation was offset by decreased residence time of the aerosol. We conclude that the Ultravent nebulizer can be used to nebulize drugs in a standard neonatal circuit, although the dose delivered is small. Tidal volume and aerosol residence time are important determinants of aerosol delivery.

Animals↗
PubMed1991

Genetic analysis in vibrio.

Bacteria of the genus Vibrio are remarkably diverse, and until recently the methodology for genetic analysis consisted of a patchwork of different approaches, many of which were narrowly applicable to a single species. The invention of the recombinant DNA technology and the subsequent innovations in transposon mutagenesis and in transductive and conjugative gene transfer techniques have led to the development of very powerful and general strategies for genetic analysis of species of Vibrio. The striking synergy of combining recombinant DNA, transposon, and gene transfer methods is particularly evident in the construction of transposons which generate gene fusions and of broad host range plasmids which deliver transposons and mutated genes and which mobilize chromosomes. With such tools it should be possible to perform advanced genetic analysis on the many undomesticated species of Vibrio still to be explored.

Cloning, Molecular↗
PubMed1991

Object relations in childhood and adolescence: the development of working representations.

This article describes two studies based on an integration of theory and research in object relations and developmental social cognition. The following four dimensions were assessed in 2nd and 5th graders and in 9th and 12th graders using Thematic Apperception Test (TAT) responses and Ss' descriptions of meaningful interpersonal episodes: complexity of representations of people, affect-tone of relationship paradigms, capacity for emotional investment in relationships and moral standards, and understanding of social causality. In both studies, developmental differences emerged on all measures except affect-tone, as expected. Results document object-relational development beyond the preoedipal years and suggest the diagnostic importance of distinguishing multiple dimensions of object relations rather than considering object relations as a single or unitary developmental line.

Adolescent↗
PubMed1991

Skin prick testing using allergen-coated lancets: a comparison between a multiple lancet device and a single lancet applied with varying pressures.

Allergen-coated lancets have been developed to simplify skin prick testing. The effect of variation in application pressure on the response to prick tests was assessed in 20 atopic subjects, and the results compared to the response obtained with a newly devised multiple lancet device (MLD), capable of holding up to eight lancets and of providing a standardized application pressure. A positive weal (greater than or equal to 7 mm2) using light pressure occurred in 2/20 subjects, compared with 14/20 after moderate pressure. The largest weals were obtained using hard pressure and with the MLD (all 20 subjects obtained positive weals) and there was no significant difference in weal size between the two. There was evidence of a late reaction in 4/17 subjects with the MLD and with hard pressure applied to a single lancet, but in only one with moderate and in none with light pressure. Thus both the early and late skin responses are dependent on the pressure applied. The newly designed MLD allows skin prick tests to be performed using a standard pressure. It is also convenient for multiple allergen testing of uncooperative children.

Adult↗
PubMed1991

Cerebral blood flow velocity changes after rapid administration of surfactant.

A computer linked Doppler system was used to make continuous measurements of cerebral blood flow velocity (CBFV) from the middle cerebral artery, mean arterial blood pressure (MAP) from the umbilical artery, and heart rate before, during, and for 20 minutes after the endotracheal administration of 200 mg/kg of porcine surfactant in 10 preterm infants with respiratory distress syndrome. Within two minutes of surfactant administration, there was a median fall of 6 mm Hg (15%) fall in MAP and 36% in CBFV. There was a change in the Doppler spectra with almost complete loss of diastolic velocities. A rapid reduction in pulmonary vascular resistance with consequent left to right ductal shunting is one possible cause. These acute changes in MAP and CBFV after bolus surfactant administration may increase the risk of intraventricular haemorrhage.

Blood Flow Velocity↗
PubMed1991

Use of transcutaneous oxygen tension, arterial oxygen saturation, and respiratory resistance to assess the response to inhaled methacholine in asthmatic children and normal adults.

Respiratory resistance (Rrs6), transcutaneous oxygen tension (PtcO2), and oxygen saturation (SaO2) were measured during methacholine challenge in 15 asthmatic children and six normal adults. During bronchoconstriction, induced by a wide range of inhaled methacholine concentrations (0.5-256 g/l), the rise in Rrs6 was reflected by a fall in PtcO2 in all subjects. Although there was a significant mean fall in SaO2 at maximum bronchoconstriction there was no consistent relation between changes in SaO2 and Rrs6. The inhaled dose of methacholine causing a 40% increase in Rrs6 (PD40Rrs6) and a 20% fall in PtCO2 (PD20PtcO2) was calculated for each subject. There was no significant difference in mean PD40Rrs6 and PD20PtcO2, and the relation between the two was similar in the asthmatic children and the normal adults. It was therefore concluded that the measurement of PtcO2, but not SaO2, during methacholine challenge can be used for the assessment of bronchial responsiveness, and that it could prove particularly useful for children too young to cooperate with lung function tests.

Administration, Inhalation↗