In vitro platelet release by rat megakaryocytes: effect of metabolic inhibitors and cytoskeletal disrupting agents

Development of an in vitro visual assay facilitated the study of large numbers of megakaryocytes undergoing proplatelet formation in short-term cultures. Approximately 9% of megakaryocytes formed platelets during a 24-hour period. In the presence of an inhibitor of anaerobic glycolysis (NaF), proplatelet formation was inhibited, whereas inhibitors of respiration (NaCN) did not significantly (P greater than 0.05) decrease proplatelet formation. Presence of the microtubule-disrupting agents colchicine and vincristine sulfate in culture medium inhibited proplatelet formation, whereas the microfilament-disrupting agent cytochalasin B had a less pronounced inhibition.     

In vitro platelet release by rat megakaryocytes: effect of heterologous antiplatelet serum

A visual assay to study megakaryocyte platelet release via proplatelet formation in vitro was established. Samples of megakaryocyte-enriched rat bone marrow were incubated (37 C) in RPMI-1640 medium with 15% autologous serum in specially prepared chambers. In the culture system, approximately 6% of megakaryocytes formed proplatelet processes within 24 hours. Inclusion of a heterologous antiplatelet antibody in the culture system inhibited proplatelet formation, compared with that in controls.     

Intravascular Leukostasis and Systemic Aspergillosis in a Horse With Subleukemic Acute Myelomonocytic Leukemia

Leukemia is a neoplastic disease of one or more of the cell types of the hemopoietic system and is rarely diagnosed in the horse. This report describes a case of subleukemic acute myelomonocytic leukemia in an 11 -year-old gelding. Preliminary cytological diagnosis was supported by two types of laboratory investigations. Cytochemical characterization of blood and bone marrow neoplastic cells was consistent with a myelomonocytic origin. Neoplastic blast cells in peripheral blood were labeled by monoclonal antibodies specific for cell surface molecules of horse granulocytes, but they were not labeled by antibodies to T- or B-lymphocytes or macrophages. Treatment was attempted but was unsuccessful. At necropsy, intravascular leukostasis was present in all tissues examined. Fungal hyphae were also found in lung interstitium and colonic submucosa, suggesting the presence of a systemic mycosis. Nucleated cells were isolated from peripheral blood and cultured in vitro; they survived for up to 2 weeks and had evidence of cell division that was not sustained. Frozenthawed cells stored in liquid nitrogen were also successfully cultured in vitro, but no permanent cell lines could be established.     

Effects of various treatments on induced chronic aflatoxicosis in rabbits

Male New Zealand White rabbits were orally given 0.05 mg of aflatoxin B1 (AFB1)/kg of body weight daily for 10 days and were treated with glutathione-precursors and depletor, antibacterial agents, or sodium thiosulfate. The drug administered, the mortality, and the mean survival time were as follows: corn-oil controls (0), euthanatized at 25 days; AFB1-controls (2), 21 days; AFB1 and saline controls (2), 22 days; cysteine and AFB1 (5), 13 days; methionine and AFB1 (5), 12 days; sodium thiosulfate and AFB1 (2), 21 days; sulfadimethoxine and AFB1 (1), 24 days; oxytetracycline and AFB1 (0), euthanatized at 25 days; and ethyl maleate and AFB1 (3), 21 days. Clinical signs of toxicosis included decreased feed consumption during AFB1 administration, loss of body weight or failure to gain, and death. Clinicopathologic changes included increases in serum bilirubin concentration and alanine aminotransferase and aspartate aminotransferase activities. Prothrombin and activated partial thromboplastin times were lengthened. Plasma fibrinogen concentration was decreased. Changes in PCV, hemoglobin concentration, and serum alkaline phosphatase were unremarkable. Oxytetracycline had protective effects against chronic aflatoxicosis in rabbits. Cysteine and methionine enhanced chronic aflatoxicosis.     

Assessment of Genetic Variability in the Coding Sequence of Melatonin Receptor Gene (MTNR1A) in Tropical Arid Sheep Breeds of India

Seasonal behaviour in sheep, which varies in tropical and temperate environmental conditions, is a matter of study, because it can provide a clue to address the problem of seasonality in sheep. Melatonin receptor is the membrane‐bound G‐coupled receptor, sensing the message of photoperiodic cues thorough melatonin. Restriction fragment length polymorphism (RFLP) studies were carried out to assess the variability of gene at G612A and C606T SNPs in MTNR1A gene, which have been studied to be markers for out‐of‐season breeding. Allelic frequency distribution corresponded to higher frequency of GG and CC genotype, in tropical arid sheep breed in comparison with temperate region sheep breed. PCR amplification of MTNR1A gene of 30 animals was performed and single nucleotide polymorphisms (SNPs) identification was carried out using Lasergene software. Seven SNPs/mutations were identified, but most of them were synonymous, except the one G706A, leading to substitution of valine by isoleucine. Polyphen‐2 analysis of G706A mutation revealed that it is a benign mutation. Two important SNPs C426T and G555A, which were identified in temperate sheep breeds, could not be traced in Magra and Marwari breeds of sheep. Thus, the Magra and Marwari breeds of tropical, arid region demonstrated the presence of both polymorphic SNPs markers G612A and C606T, associated with out‐of‐season breeding. GG and CC genotypes were having a higher prevalence in the studied population.