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Biomedical subjects

W Richards

Publications and source records attributed to W Richards.

At least 19 recordsLinked to original sources
PubMed1992

Differential plasma duration of antiplatelet-activating factor and antihistamine activities of oral Sch 37370 in humans.

Preclinical studies have established that Sch 37370 (1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]-cyclohepta [1,2-b]pyridin-11-ylidene)piperidine) is an orally active antagonist of platelet-activating factor (PAF) and histamine H1-receptors with potential therapeutic use in the treatment of asthma. To evaluate the efficacy and duration of anti-PAF and antihistamine actions of oral Sch 37370 in humans, a single dose (5 mg/kg) of Sch 37370 was given orally to each of 10 male subjects in a placebo-controlled, double-blind crossover study. Blood samples were drawn before and at various times (2 to 48 hours) after Sch 37370 or placebo. Plasma samples were analyzed for Sch 37370 by a gas chromatographic method, for the anti-PAF activity by measuring the aggregation of platelets stimulated with PAF, and for the antihistamine activity by measuring displacement of [3H]pyrilamine from rat brain membrane binding sites. The plasma anti-PAF activity declined from high levels at 2 hours to barely detectable levels at 24 hours; however, significant activity was still present at 12 hours. The plasma levels of Sch 37370 closely paralleled the anti-PAF profile. The plasma antihistamine activity reached a maximum within 2 to 8 hours and declined thereafter. However, 48 hours after Sch 37370, the antihistamine activity was still present at a significant level in most subjects. It is concluded that, in humans, oral Sch 37370 antagonizes both PAF and histamine with plasma antihistamine activity lasting longer than plasma anti-PAF activity.

Administration, Oral↗
PubMed1992

Hypercarbia during carbon dioxide gas insufflation for therapeutic laparoscopy: a note of caution.

During the past decade, the number of laparoscopic procedures performed in the United States, primarily with cholecystectomy, has increased phenomenally. We recently had a patient who developed hypercarbia and cardiovascular compromise during laparoscopic cholecystectomy. The cardiovascular compromise was caused by mechanical factors directly related to increasing intra-abdominal pressures affecting ventilation and venous return as well as the absorption of carbon dioxide (CO2) into the circulation, leading to acidosis and further depression of the cardiopulmonary system. Cardiovascular compromise can be avoided with early recognition of increased end-tidal CO2 concentrations and by preventing intra-abdominal pressures from exceeding 16 mm Hg.

Aged↗
PubMed1979

Why rods and cones?

A key problem in vision is to normalize one's lightness scale so that surface reflectances are always assigned the same gray value regardless of the illumination level. The solution requires an assessment of the relation between the strength of the illuminant and the strength of the image signal-information that is not available in the image alone. However, the level of scattered light in the optical system does provide an independent measure of the illuminant strength, and can be used to solve the lightness scale normalization problem. To do this requires a comparison between two imaging systems, each of which respond differently to the internal optical scatter. The rod and cone systems have properties that are ideally suited for such a role.

Color Perception↗
PubMed1979

Fetal phenotypic expression by adult rat hepatocytes on collagen gel/nylon meshes.

Hepatocytes from adult rats were maintained in primary culture for up to 10-13 days on nylon meshes coated with a thin layer of rat tail collagen gel. Their ultrastructure closely resembled that of the liver parenchymal cell in vivo, but hepatocytes in late culture exhibited a pronounced buildup of microfilaments beneath their apical cell surface. Hepatocytes in early and late cultures secreted albumin, transferrin, and alpha1-acid glycoprotein into the medium; they exhibited a 7- to 10-fold induction of tyrosine aminotransferase activity by dexamethasone; and they expressed an alkaline phosphatase that was similar to that of normal rat liver with respect to its inhibition by the liver enzyme inhibitor L-homoarginine. In addition, the hepatocytes in culture demonstrated phenotypic changes characteristic of fetal liver parenchymal cells. These changes, which paralleled an increase in DNA synthesis, included the expression of and linear increase in the activity of the fetal liver cell enzyme gamma-glutamyl transpeptidase, an increased production of alpha1-fetoprotein, and a change in the substrate specificity of fructose-bisphosphate aldolase to that of the fetal liver isozyme.

Animals↗
PubMed1979

Review of intensive care unit admissions for asthma.

A review of ICU admissions for asthma to the Childrens Hospital of Los Angeles was conducted for the period January 1969 through July 1977. The admission rate remained relatively constant during this period. Patients requiring ICU admission tended to be young, intractable severe asthmatics whose asthma started at a very young age. There were three patients who had no previous history of asthma. The incidence of pneumonitis/atelectasis was somewhat greater than has been reported for patients hospitalized for status asthmaticus. A significant number of children received neither intravenous corticosteriods, sympathomimetics nor oxygen therapy while hospitalized prior to transfer to the ICU. Those children receiving mechanical ventilation or intravenous isoproterenol tended to be somewhat younger and had a higher incidence of pneumonitis/atelectasis and more abnormal blood gas determinations than their counterparts who were not similarly treated. Mechanical ventilation was administered to 15 patients and 19 patients received intravenous isoproterenol. Intravenous isoproterenol resulted in prompt improvement in most patients; except for one patient who experienced cardiac arrhythmia (reversed when the dosage was decreased), this medication was well-tolerated.

Adolescent↗
PubMed1978

Steroid-dependent asthma treated with inhaled beclomethasone dipropionate in children.

The efficacy of beclomethasone diproprionate aerosal (BDA) was studied in 27 steroid-dependent asthmatic children. In the double-blind portion of the study BDA was found to be superior to placebo. The benefits of BDA therapy were sustained through the two-year, open-label portion of the study. Adverse effects were few and minor. Transfer from oral corticosteroid therapy to BDA was carried out uneventfully and was not associated with untoward effects.

Adolescent↗
PubMed1978

Routine laboratory determinations in pediatric allergic disease.

Clinical and laboratory data were extracted from the medical records of 285 consecutive children after completion of their evaluations for suspected atopic disease. Blood eosinophilia, determined from a routine complete blood count, was present in more than 60% of patients tested. Nasal smear for eosinophils or a direct eosinophil count provided little additional evidence of atopic reactivity in simultaneously tested patients. Total serum IgE concentration was elevated in 75% to 81% of the children with asthma, nasal allergy and atopic dermatitis and an elevated serum IgE concentration or blood eosinophilia, or both, was noted in 85% of the patients studied. Selective IgA deficiency was documented in three children and hyperimmunoglobulinemia was found in 20 others. Serum complement activity was normal in 10 children with persistent urticaria, allergy, IgE, eosinophilia, immunoglobulins, complement.

Child↗
PubMed1977

Visual texture discrimination using random-dot patterns.

A method for generating random-dot textures is described that provides statistical control of any n adjacent points (n-grams), while leaving constant the statistics of shorter spans. The method thus allows the experimenter to isolate statistics of n-grams of any span length to determine the nature of their influence on texture discrimination. Variables that control phase are relatively unimportant. The most significant variables are constraints imposed upon span lengths less than 3 that regulate gray level and spatial frequency content. However, span lengths of 3 or greater may still influence discrimination by altering the distribution of the spatial-frequency content.

Computers↗
PubMed1977

Air leak syndromes as complications of respiratory disease in infancy and childhood.

Pneumothorax, pneumomediastinum and subcutaneous emphysema are potential complications of a variety of pediatric illnesses. A review by the authors confirms the reports of others that asthma is the primary medical cause of pneumothorax and subcutaneous emphysema and that a variety of inflammatory and obstructive lesions can be associated with extra-vasation of pulmonary air. Pneumothorax infrequently complicates asthma. Asthma-associated pneumomediastinum rarely requires vigorous therapeutic intervention and massive subcutaneous emphysema may necessitate tracheostomy. Pressurized delivery of sympathomimetic aerosols have been condemned by some as an unnecessary cause of iatrogenic air leak. The data of the authors indicate that this form of therapy rarely causes air leak syndromes. The pathophysiology of extravasation of pulmonary air is reviewed.

Asthma↗