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Biomedical subjects

M S Read

Publications and source records attributed to M S Read.

At least 73 records · Page 4Linked to original sources
PubMed1983

Venom coagglutinin for detection of von Willebrand factor activity in animal plasmas.

Platelet-aggregating vWF activity in several animal species is difficult to detect with either the ristocetin co-factor test or the PAF test using human platelets, indicating considerable species restriction in applicability of these procedures. VCA, a recently described second "activator" of vWF, was found not to be restrictive as to species and readily elicited the vWF response in all 13 animal plasmas tested. For any one of the animal plasmas, the vWF-dependent platelet aggregation reaction can be demonstrated by using VCA with either homologous or heterologous species of platelets. VCA was employed with lyophilized platelets in two types of platelet aggregating test systems, a macroscopic procedure and an aggregometric method. Many of the animal plasmas (dog, rabbit, horse, cow, cat, sheep, and goat) had about three to five times the plasma vWF content of human plasma. Pig and rat plasmas had vWF levels approximating those of human plasma. Guinea pig plasma had about half as much vWF as human plasma. VCA also caused a well-defined vWF-dependent platelet response in PRPs. The data suggest considerable differences in the rate of aggregation of platelets from different species. Bioassay of vWF can be performed with the different animal plasmas if the source of platelets and the VCA concentration are controlled. VCA thus appears to provide a broad-spectrum probe for vWF and is effective in the various species combinations of plasma and platelets.

Animals↗
PubMed1982

Malnutrition and behavior.

Severe malnutrition during the fetal or infancy period in animals and humans decreases brain size, reduces the number of brain cells, and results in behavioral abnormalities. The relationship between lesser degrees of malnutrition and intellectual development is more complex. Social, genetic, and other factors assume greater roles under the latter conditions. Before we can draw firm conclusions that malnutrition per se is the cause of mental subnormality, we must complete analyses from on-going longitudinal studies in order to clarify the role of parental interaction with malnourished child and of the social environmental factors which accompany malnutrition.

Achievement↗
PubMed1981

Von Willebrand syndrome induced by a Bothrops venom factor: bioassay for venom coagglutinin.

Hereditary deficiency of the macromolecular Factor VIII complex results in classic von Willebrand disease in man and animals, a bleeder state characterized by loss of the multiple biologic activities associated with the Factor VIII complex, including the platelet-aggregating von Willebrand factor. The bleeding time is also long. Venom coagglutinin, a Bothrops factor that causes platelet aggregation in vitro, depletes the plasma of its von Willebrand factor. The rate of platelet aggregation is a function of the amount of the coagglutinin present. Based on this observation, a sensitive and quantitative assay for the venom coagglutinin was developed. We administered the purified Bothrops factor to normal pigs and dogs and induced a von Willebrand syndrome similar to the inherited disease. The plasma von Willebrand factor was severely depleted; the antihemophilic factor and the Factor VIII-related antigen were not depleted as much. The bleeding time was normal. During the induction phase of the syndrome, transient thrombocytopenia with a long bleeding time occurred. The pig was less sensitive than the dog to the effect of coagglutinin. The severity of the syndrome is determined by the amount of venom coagglutinin administered. It is suggested that the syndrome could be induced in any mammalian species because the plasma of all mammals tested in vitro is sensitive to the venom factor. This model provides another avenue for the study of the heterogeneity of the Factor VIII complex and the pathophysiology of its components.

Animals↗
PubMed1978

Venom coagglutinin: an activator of platelet aggregation dependent on von Willebrand factor.

A platelet-aggregating activity was found in many snake venoms, predominantly those of the genus Bothrops, that is apparent only in the presence of the platelet-aggregating von Willebrand factor of plasma. It is designated "venom coagglutinin." The coagglutinin can be largely separated from the thrombin-like enzyme of the venoms by ion-exchange chromatography. The venom factor acts on formaldehyde-fixed platelets and is effective with decalcified, heparinized, and afibrinogenemic plasmas but not with severe von Willebrand disease plasmas or with normal plasmas in which the von Willebrand factor has been neutralized by specific antibodies. Use of this coagglutinin permits the assay of von Willebrand factor without the many disadvantages of the ristocetin test. The coagglutinin is active with human, dog, pig, and bovine plasmas and with platelets of any one of these species. This broad-spectrum activity without regard to species contrasts with the ristocetin-resistance of many combinations of plasma and platelets from various species. The assay provides a procedure for studying human, porcine, and canine von Willebrand disease. The lack of species specificity of the coagglutinin suggests that it may be a universal activator of the von Willebrand factor-platelet reaction.

Animals↗
PubMed1977

Longitudinal studies on the effects of malnutrition, nutritional supplementation, and behavioral stimulation.

Six major Western Hemisphere longitudinal studies of malnutrition and development are in their final stages. These studies are taking place in Columbia, Guatemala, Mexico, and the United States. As a step toward synthesis of the results, a conference was held at Cali, Colombia, with the aim of clarifying differences and similarities. The following features of each study were considered: The starting and completion dates; the research design (including scheduled periods of observation and the presence or absence of nutritional supplements and/or stimulation); the populations involved, their home diets, and the specific supplements and stimulation received; procedures and measurements used in the study; and any general conclusions reached. The conference also identified opportunities and needs for exchange of information between projects and for a collaborative approach to such specific problems and topics as birth-weight, physical growth, and behavioral development.

Adolescent↗
PubMed1974

Comparison of certain functions of human platelets separated from blood by various means.

Human platelets separated from blood by six different methods have been compared for aggregability, adhesion to glass, adenine nucleotide content and release, and adenosine triphosphatase and cholinesterase activities. Methods of separation of platelets from blood included three differential centrifugation technics, gel filtration and two albumin density gradient methods. Platelets prepared by the different methods aggregated comparably except those separated by albumin density gradient technics which tended to be hyporeactive. Differences in adhesion to glass, adenine nucleotide content and release, and monitored enzyme activities of the various platelet preparations were noted in several cases but were not marked in general. Ultrastructural studies, reported elsewhere, revealed that platelets separated by the method of Mustard or by gel filtration were less altered morphologically than those separated by the other methods. Platelets separated from blood by gel filtration also appeared somewhat superior functionally to platelets separated by other methods.

Adenosine Diphosphate↗