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Biomedical subjects

S L Raymond

Publications and source records attributed to S L Raymond.

12 recordsLinked to original sources
PubMed1992

Epidemiologic features of von Willebrand's disease in Doberman pinschers, Scottish terriers, and Shetland sheepdogs: 260 cases (1984-1988)

During a study period from 1985 through 1988, plasma von Willebrand's factor antigen (vWF:Ag) concentration was measured as a marker for prevalence of the von Willebrand's disease (vWD) trait in Doberman Pinschers (doberman, n = 5,554), Scottish Terriers (scottie, n = 1,363), and Shetland Sheepdogs (sheltie, n = 4,279). Significant increase in prevalence of the trait was seen in scotties and shelties during this period. In 1988, 73% of dobermans, 30% of scotties, and 28% of shelties tested had abnormal vWF:Ag concentration (less than 50% vWF:Ag). We found significant differences between breeds with respect to age and vWF:Ag concentration of clinically affected dogs at time of diagnosis. The affected dobermans were older (doberman mean age, 4.6 years; scottie mean age, 1.7 years; sheltie mean age, 1.9 years) and had higher concentration of plasma vWF:Ag (doberman mean vWF:Ag, 15%; scottie mean vWF:Ag, 0%; sheltie mean vWF:Ag, 8%). Bleeding in affected dogs of all 3 breeds was observed predominantly from mucosal surfaces and from cutaneous sites of surgery or trauma. The most common site of mucosal bleeding in scotties and shelties was oral or nasal cavity, and in dobermans was the urogenital tract. Differences in clinical manifestations of vWD in purebred dogs may reflect heterogeneous defects within the vWF gene, causing a variety of abnormalities in production, structure, and function of vWF protein. Analogous to vWD in human beings, acquired deficiencies of vWF may also contribute to the clinical variability of vWD in dogs.

Animals↗
PubMed1990

Clinical and laboratory features of a severe form of von Willebrand disease in Shetland sheepdogs.

Ten clinically affected Shetland Sheepdogs were evaluated to define their severe bleeding diathesis and were determined to have von Willebrand factor antigen (vWF:Ag) values less than 0.1% by ELISA assay. The virtual absence of vWF protein by ELISA assay and on multimeric analysis was diagnostic of either homozygosity or probable double heterozygosity for the canine von Willebrand disease (vWD) gene. Clinically affected dogs have type-III vWD and are the offspring of 2 heterozygous parents carrying type-I vWD. Twenty-three percent (1,428 dogs) of the more than 6,000 Shetland Sheepdogs screened for vWD at our facility since 1982 tested within the heterozygous carrier range for the common type-I form of this inherited disorder. Veterinarians and breeders should be aware of the potential for bleeding associated with elective and medical procedures in Shetland Sheepdogs and should use caution when breeding carriers of vWD because of the risk of producing clinically affected offspring with severe type-III vWD.

Animals↗
PubMed1986

Defective platelet-fibrinogen interaction in hereditary canine thrombopathia.

A unique, intrinsic, hereditary canine platelet disorder attributable to abnormal fibrinogen receptor availability is described. Thrombopathic platelets from 13 severely affected basset hounds failed to aggregate in response to all agonists tested except thrombin. Normal platelet interaction with the various stimuli was inferred on the basis of their ability to elicit unimpaired shape change in thrombopathic platelets. No quantitative differences in major platelet membrane glycoproteins, intraplatelet fibrinogen, adenine nucleotides, or serotonin uptake were detected. Dense granule secretion was impaired. The ultrastructural appearance of thrombopathic platelets was normal. Fibrinogen-platelet interaction was evaluated by reacting platelet-rich plasma (PRP) with fibrinogen coupled to polymeric acrylonitrile beads and scoring the extent of stimulus-induced agglutination. The aggregatory responses of normal and thrombopathic platelets were closely correlated with fibrinogen receptor availability. In contrast to human platelets, epinephrine-stimulated canine platelets did not interact with immobilized fibrinogen, and arachidonate generally induced only weak agglutination. Thrombopathic platelets agglutinated fibrinogen beads at reduced rates when stimulated with physiologic doses of thrombin and high-dose calcium ionophore, A23187. Our data suggest that thrombin-mediated induction of canine platelet fibrinogen receptors may proceed by pathway(s) alternate to those shared by other platelet agonists, and/or that secreted granule constituents may act synergistically with thrombin to overcome inhibition of signal-response-coupled reactions mediating the interaction of fibrinogen with its receptor. This congenital platelet defect provides further evidence, in a species other than human, for the pivotal role of fibrinogen receptor induction in platelet aggregation.

Adenine Nucleotides↗
PubMed1979

Platelet membrane glycoproteins in normal dogs and dogs with hemostatic defects.

Glycoproteins solubilized from membrane-enriched fractions of platelets from dogs with TT or VWD and from normal controls were compared by SDS-PAGE. The results were similar to those for the analogous human disorders. Both normal and VWD canine platelet MPs contained three major glycoproteins as well as four smaller-molecular-weight proteins that stained for carbohydrate with the PAS reagent. In contrast, MPs from dogs with TT had a higher concentration of GP I, a varied expression of GP II, and a lower concentration of GP III. The findings re-emphasize the value of comparative studies of these models of human hemostatic defects.

Animals↗
PubMed1977

Spontaneous atrial thrombosis in aged Syrian hamsters. II. Hemostasis.

Coagulation and fibrinolysis were studied in a colony of aged Syrian hamsters with spontaneous atrial thrombosis, and the results are consistent with concomitant consumption coagulopathy. In comparison to age- and sex-matched hamsters from the same colony, those with atrial thrombi had significantly prolonged prothrombin and partial thromboplastin times, reduced levels of factors II, VII, VIII and X activities and plasminogen; and concentrations of fibrinogen-fibrin split products in excess of 80 microgram/ml. Hematocrits of the thrombosed animals were significantly decreased, total plasma proteins were increased, leukocyte counts were within normal limits, and platelet counts were about half those of the controls. Thrombosed hamsters had significantly reduced plasma albumin content, increased alpha1-, beta-, and gamma-globulins, and reduced A/G ratios. Aged sick hamsters demonstrable thrombi also had reduced coagulation and fibrinolytic activities and platelet counts, but their fibrinogen levels were markedly elevated, and fibrinogen-fibrin split products were either absent or present in trace amounts. This suggests an earlier and/or less acute form of the thrombotic process.

Aging↗
PubMed1975

Characterization of the fawn-hooded rat as a model for hemostatic studies.

A large colony of fawn-hooded (FH) rats, comprising five original families and six generations of their progeny, was developed for genetic and comparative studies of their bleeding tendency. The characteristics of the bleeding diathesis in these rats are similar to those originally reported in related rats by Tschopp and Zucker. FH rats have normal clot retraction, ADP-induced platelet aggregation and platelet ADP; variable aggregation with collagen; minimal aggregation with adrenaline and cobra venom factor; and reduced platelet ATP, ATP/ADP ratio, serotonin content and -14C-serotonin release. In comparison to age- and sex-matched Wistar rats, FH rats have significantly prolonged partial thromboplastin time, shortened Russell's viper venom time and increased factor X and XI levels. Other coagulation screening tests and specific assays for fibrinogen, plasminogen and factors VII, VIII and IX were normal. Some age- and sex-related differences in coagulation and other parameters were observed within each rat strain. Plasma proteins, glycoproteins and ceruloplasmin (copper oxidase activity) showed no abnormalities, nor did initial studies of immunoglobulins and complement. However, FH rats have significantly lower glucose and higher cholesterol levels than comparable Wistar rats.

Adenine Nucleotides↗
PubMedDate not supplied

Evaluation of platelet cryopreservation techniques by isolated kidney perfusion.

The isolated perfused rabbit kidney, a model system used previously to assess platelet function, was adapted for evaluation of human platelet cryopreservation techniques. A new, simple, efficient device for controlling cooling rates before, during, and after freezing was used. Platelet concentrates frozen with 5 per cent dimethyl sulfoxide (DMSO) under different conditions were the most effective of those tried in maintaining the hemostatic function and vascular integrity of perfused kidneys. Our studies indicate that the isolated, perfused rabbit kidney can be used to evaluate platelet cryopreservation techniques and is potentially adaptable for studies of organ cryopreservation.

Animals↗