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Biomedical subjects

R Brown

Publications and source records attributed to R Brown.

At least 613 records · Page 34Linked to original sources
PubMed1987

Changes in lectin binding by differentiating cutaneous keratinocytes from the newborn rat.

Surface glycoconjugates of cells from the basal layer of the skin of the newborn rat bind the isolectin I-B4 from Griffonia simplicifolia (GS I-B4) (alpha-D-galactosyl specificity). Surface glycoconjugates of the differentiated cells from the spinous and lower granular layers bind Ulex europeus agglutinin I (UEA) (alpha-L-fucosyl specificity). The change from GS I-B4 binding to UEA binding was studied in rat keratinocytes that were cultured as a monolayer in low-calcium medium until confluence, and then induced to stratify and terminally differentiate by raising the calcium concentration of the medium. The cells in the monolayer had basal cell morphology and exhibited surface binding of GS I-B4. However, at confluence, 30-40% of these cells also showed surface binding of UEA. There was an increase with time in the number of cells which bound both GS I-B4 and UEA. Raising the calcium concentration of the medium resulted in an increase in UEA binding. Cells of the upper layers of the stratifying cultures showed intense UEA binding but did not show any GS I-B4 binding. Double staining of frozen sections of newborn rat skin with fluorescein-conjugated GS I-B4 and rhodamine-conjugated UEA revealed that the surfaces of cells from the lower spinous layer bound both lectins. Thirty percent of the major glycoprotein fraction, that was isolated from the membranes of the epidermal cells of the newborn rat and was bound to an affinity column of UEA-Sepharose 4B, was also bound to an affinity column of GS I-B4-Sepharose 4B. These results indicate that surface glycoconjugates of rat keratinocytes differentiating in culture exhibit a change from GS I-B4 binding to UEA binding; the change in the cell surface glycoconjugates that results in the appearance of UEA binding, a feature of differentiated cells, occurs independently of stratification; and the change from GS I-B4 binding to UEA binding probably involves an "intermediate" glycoconjugate that binds both GS I-B4 and UEA and is found on the surface of cells from the lower spinous layer of the epidermis of the newborn rat.

Animals↗
PubMed1987

Genetic markers in Australian Caucasian subjects with coeliac disease.

A group of 69 unrelated Australian coeliac subjects (41 adult onset and 28 childhood onset) were typed for for HLA-A, B, DR and DQ antigens. Immunoglobulin allotypes were also determined in 36 of these patients. An association between coeliac disease and the antigens DR3, DR7 and DQw2 was confirmed in this population. There was no significant difference in antigen frequencies between childhood and adult onset coeliac disease, although the association with DR7 was stronger in the childhood group. All coeliac patients who did not carry DR3 or DR7 were found to be DR4 positive. No association was demonstrated between coeliac disease and any immunoglobulin allotype, either in the absence of HLA antigens B8 and DR3 or in male coeliac patients.

Australia↗
PubMed1987

Psychological adjustment and diabetic control.

Glycosylated haemoglobin concentrations, C peptide secretion, insulin dose, psychiatric state, intellectual functioning, and the extent to which the implementation of the diabetic regimen was shared between parent and child were studied in a cross sectional study of 50 children with diabetes aged 6-16. Indications of psychological disturbance in the children and their parents predicted low glycosylated haemoglobin concentrations in the children, and accounted for 44% of variance in blood glucose control. The child's early and independent participation in the implementation of the diabetic regimen was associated with poor control.

Adaptation, Psychological↗
PubMed1987

Clinical aspects of X-linked hypohidrotic ectodermal dysplasia.

Boys with X-linked hypohidrotic ectodermal dysplasia and their families were studied. Many suffered severe illness in early childhood and nearly 30% died; many had feeding problems, severe fever, atopic disease, and recurrent respiratory infections. Some infants failed to thrive. We found no consistent common endocrine or immunological abnormality, although, most had abnormal immunoglobulin production. This may be related to the abnormal mucosa of the gastrointestinal and respiratory tracts which exacerbates the chronic obstructive airways disease found later in life in those who smoke. Mental handicap was not a feature, although convulsions sometimes occurred during fever. Early diagnosis is important to avoid attacks of severe fever and so that rational management may be planned for other problems that arise. Dental advice should be sought before school age and genetic counselling may also be required. Many female carriers may be recognised at clinical examination: their affected sons can then be diagnosed more readily.

Adolescent↗
PubMed1987

High-level quadriplegics perceive lung volume change.

We tested the ability of tracheostomized, high-level quadriplegics to detect changes in ventilator-delivered tidal volume. Single breaths larger or smaller than control breaths were delivered, and the subjects indicated which breath was altered in a forced-choice procedure that minimizes the effect of subject bias. Quadriplegic patients detected changes in tidal volume of as little as 100 ml. Their ability to detect changes was comparable to that of a group of normal subjects similarly tested. These quadriplegic patients had little or no somatic sensation below the neck, and airways above the tracheostomy were not exposed to the stimulus. The quadriplegics consistently and emphatically reported that the sensation used in volume discrimination arose within the chest.

Adult↗
PubMed1987

Cardiovascular performance during bronchospasm in dogs.

In 8 anesthetized mongrel dogs, we studied the effects of carbachol-induced bronchoconstriction (BC) on the cardiovascular system. Inhalation of carbachol in an amount sufficient to produce at least a 50% decrease in lung conductance (GL) did not lead to significant changes in cardiac output, mean transmural left atrial (Pla) or right atrial pressure, end-diastolic left ventricular septal-lateral dimension, left ventricular apex to base dimension, or in end-diastolic right ventricular septal to lateral dimension during expiration. Mean transmural pulmonary arterial pressure rose and mean transmural aortic pressure (Pao) fell during BC. During inspiration, there were significant increases in transmural left atrial pressure, Pla, associated with decreases in end-diastolic left ventricular septal-lateral and apex-base dimensions. End-diastolic right ventricular septal-lateral dimension increased during inspiration. Beat-to-beat aortic flow (Qao) decreased during inspiration, while pulmonary arterial flow increased. There were no changes in transmural Pao during inspiration measured at the nadir of aortic flow. During BC, these changes were exaggerated, but remained qualitatively the same. The magnitude of the inspiratory decrease in pleural pressure (Ppl) was shown to be linearly related to the magnitude of the change in GL, and the magnitude of the inspiratory decrease in Pao and Qao (pulsus paradoxus) was shown to be linearly related to the magnitude of the inspiratory swing in Ppl. Although vagotomy significantly altered the pattern of respiration such that tidal volume increased and respiratory rate decreased, it did not substantially alter the responses of the cardiovascular system to breathing during BC. We conclude: the inspiratory decrease in Pao and Qao (pulsus paradoxus) is associated with a decrease in left ventricular end-diastolic filling, and a stiffening of the left ventricle; these changes are exaggerated during BC as a result of the exaggerated inspiratory swings in Ppl; the effects on left ventricular dynamics are mediated only in part through increases in right ventricular end-diastolic filling operating through the mechanism of ventricular interdependence; changes in left ventricular afterload appear to play little role in determining the responses seen.

Airway Resistance↗
PubMed1987

Gas exchange during constant flow ventilation with different gases.

To investigate the mechanisms of CO2 transport during constant flow ventilation, we measured arterial blood gases using air, 80% He-20% O2 (He) or 80% SF6-20% O2 (SF6) as the insufflating gas. At any given flow rate (0.2 to 1.0 L/s), PaCO2 was greatest with He and lowest with SF6. Data for all gases could be described by the equation PaCO2/Pb = 0.044 V-0.64 v0.23, where Pb = barometric pressure, PaCO2 is in mm Hg, V = insufflated flow in L/s, and v = kinematic viscosity (cm2/s). At any given flow rate, the AaPO2 was greater using SF6 than using He. These results are consistent with a 2-zone model of gas transport in which the enhancement of gas transport as V increases may be due to an increase in the turbulent diffusivity in zone I (the region affected by the jet). The decreased gas transport with He compared to air and SF6 at any V may be due to either the decreased penetration depth of zone I caused by the greater kinematic viscosity of He, or the decreased rate of gas transport in the region affected by cardiogenic oscillations (zone II) secondary to the higher molecular diffusivity of He.

Animals↗
PubMed1987

Reduced length and cost of hospital stay for major depression in patients treated with ECT.

To investigate the effect of treatment modality on length of hospital stay, the authors retrospectively studied 86 admissions of 74 patients with major depression. All 19 patients who received ECT recovered, in contrast to only 27 (49%) of 55 patients given tricyclic antidepressants or other medication. The 28 patients who had not responded to antidepressants recovered after treatment with ECT. Treatment modality had a highly significant effect on length of hospital stay: patients given ECT stayed a mean of 13 fewer days, saving more than $6,400 per patient at current rates. These findings of significant economic and therapeutic benefits in the use of ECT raise issues about treatment selection for depressed inpatients.

Aged↗
PubMed1987

Early experience of health maintenance organizations under Medicare competition demonstrations.

Between 1982 and 1985, health maintenance organizations (HMO's) entered the Medicare market under the Medicare competition demonstrations. The status and experience of these HMO's, their market areas,, and the benefit packages they offered are presented. Information from case studies of 20 of these HMO's is used to discuss the planning process through which the organizations prepared to enter the Medicare market. Data from administrative reports, submitted by the HMO's, are used to describe the operational experience, including enrollments, utilization, and financial performance.

Capitation Fee↗
PubMed1987

Respiratory infections in smokers.

Cigarette smoking alters lung anatomy and physiology and impairs host immunity long before the appearance of overt chronic obstructive pulmonary disease. These changes promote more frequent and more severe lower respiratory tract infections. Optimal management of patients who continue to smoke includes accurate and early diagnosis of respiratory tract infections and selective use of appropriate antibiotics. Specific interventions can help patients stop smoking.

Adult↗
PubMed1987

Geometric alterations produced by encircling scleral buckles. Biometric and clinical considerations.

The geometric alterations induced in the human globe by the application of an encircling scleral buckle using an in vitro model are described. Both a thin, solid silicone band, and a thicker, oval element produces an encircling buckling effect of predictable height and width. With thin elements, height and width are a linear function of horizontal shortening of the band. A scleral buckle produced by horizontal shortening, irrespective of exoplant material, results in axial lengthening. In contrast, the scleral buckling effect produced by mattress suture invagination of oval or round thicker silicone exoplants results in axial shortening, provided there is no concomitant horizontal shortening. The amount of axial shortening can be increased by using two sutures per quadrant. Since axial lengthening is associated with the potential undesirable complication of radial retinal and scleral folds, and axial shortening is not, buckles created by invagination of broad encircling elements may have certain theoretical advantages.

Air↗
PubMed1987

Unconjugated morphine in blood by radioimmunoassay and gas chromatography/mass spectrometry.

Morphine, the active metabolite of heroin, is rapidly inactivated by glucuronidation at the 3 carbon. Unconjugated (pharmacologically active) morphine was measured in postmortem blood by radioimmunoassay using an antibody-coated tube kit. The kit shows less than 0.2% cross-reactivity with codeine and morphine-glucuronide. Unconjugated morphine concentrations were confirmed by gas chromatography/mass spectrometry (GC/MS) using deuterated morphine as the internal standard. The blood was precipitated with 10% trichloroacetic acid (TCA) and concentrated hydrochloric acid (HCl), centrifuged, and decanted. The supernatant was then either diluted (unhydrolyzed) or heated to 100 degrees C, 30 min (hydrolyzed), followed by a wash with 4:1 chloroform:isopropranol. The upper aqueous layer was then saturated with sodium bicarbonate (NaHCO3) and extracted with 4:1 chloroform:isopropranol. The organic layer was evaporated, derivatized with trifluoroacetic anhydride (TFA), and analyzed by selected ion monitoring (SIM) GC/MS. Comparison of the results for unconjugated morphine by radioimmunoassay and unhydrolyzed morphine by GC/MS gave a correlation coefficient of r = 0.98, n = 100. Unconjugated morphine ranged from 0 to 100% of total morphine with a mean of 42%, n = 200, for heroin or morphine involved deaths. Review of 56 putative rapid deaths gave a mean of 68% unconjugated morphine with a range of 26 to 100%. The ratio of unconjugated to total morphine was found to be stable in postmortem blood after more than a year of storage at room temperature, within the precision of the method.

Adolescent↗