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Biomedical subjects

V Martin

Publications and source records attributed to V Martin.

At least 127 records · Page 7Linked to original sources
PubMed1977

The effects of "anti-platelet" drugs on bleeding time and platelet aggregation in normal human subjects.

The effects on hemostasis of several commonly used drugs previously described as inhibiting platelet function were evaluated in a randomized, double-blind study of 54 normal volunteers. The subjects were each given a single dose of aspirin, chlorpromazine, glyceryl guaiacolate, diphenhydramine, indomethacin or lactose placebo. A single dose of aspirin significantly prolonged the template bleeding time and inhibited secondary platelet aggregation two and 24 hours after ingestion. Single doses of indomethacin and chlorpromazine affected aggregation at two hours but had no effect on bleeding time, although multiple doses of indomethacin did prolong bleeding time. Glyceryl guaiacolate inhibited aggregation one hour after ingestion but had no effect on bleeding time. Diphenhydramine did not affect either. These findings suggest that standard doses of many commonly used "anti-platelet" drugs may have little clinical effect on the hemostatic mechanism in normal man. Results of in-vitro platelet-drug incubations may not be directly applicable to in-vivo hemostasis.

Aspirin↗
PubMed1976

Antibody-induced von Willebrand's disease: a newly defined inhibitor syndrome.

A patient is described with clinical and laboratory evidence of von Willebrand's disease (VWD) in association with lymphosarcoma. He consistently had a bleeding time of over 20 min; factor VIIAHF, VIIAGN, and VIIVWF under 20%; and severe, diffuse hemorrhage, Following transfusion with cryoprecipitate, the patient had the expected rise in VIIAGN and VIIAHF. The patient's plasma contained an inhibitor which prevented aggregation of normal platelets by ristocetin, but which did not interfere with the measurement of VIIAGN or inactivate VIIAHF activity. The inhibitor was present in serum heated at 56 degrees C for 30 min, was present in a purified IgG fraction of serum, and was precipitated by anti-human IgG. The antibody did not interact directly with washed platelets, but appeared to interact with that portion of the factor VII protein that supports ristocetin aggregation (VIIIVWF). The data provide the first explanation for the pathophysiology of the acquired von Willebrand's syndrome.

Antibodies↗
PubMedDate not supplied

Ultrastructural features of "solid cell nest" of the human thyroid gland: a study of 8 cases.

The ultrastructural features of solid cell nests (SCN), made of squamous cells, and associated calcitonin cells (C cells), of the thyroid gland were studied in only a few cases in humans. A study was performed on 8 paraffin-embedded SCN, postembedded in Epon, to look for their ultrastructural features. Immunohistochemical analysis using calcitonin antibody was performed on semithin sections of SCN to explore the presence of C cells. Three cases (37.5%) of SCN were positive for calcitonin, and electron-dense secretory granules were observed in the cytoplasm. In two of these cases, an increased number of C cells in the adjacent thyroid parenchyma was observed. The presence of ciliated and lymphoid cells, in addition to intracytoplasmic microvacuolar and microfollicular (microglandular) structures, was noticed. Ciliated cells have already been reported in embryonic rests of human and animals, but ultrastructurally for the first time in human SCN. The presence of microfollicular structures, intracytoplasmic microvacuolar, secretory granules features, and ciliated cells, in addition to lymphoid cell, suggests the existence of a common ultimobranchial stem cell for C cells or for one or more cell types of the thyroid gland.

Aged↗
PubMedDate not supplied

How many Ca(2)+ATPase isoforms are expressed in a cell type? A growing family of membrane proteins illustrated by studies in platelets.

Ca(2+) signaling plays a key role in normal and abnormal platelet functions. Understanding platelet Ca(2+) signaling requires the knowledge of proteins involved in this process. Among these proteins are Ca(2+)ATPases or Ca(2+) pumps that deplete the cytosol of Ca(2+) ions. Here, we will particularly focus on two Ca(2+) pump families: the plasma membrane Ca(2+)ATPases (PMCAs) that extrude cytosolic Ca(2+) towards the extracellular medium and the sarco/endoplasmic reticulum Ca(2+)ATPases (SERCAs) that pump Ca(2+) into the endoplasmic reticulum (ER). In the present review, we will summarize data on platelet Ca(2+)ATPases including their identification and biogenesis. First of all, we will present the Ca(2+)ATPase genes and their isoforms expressed in platelets. We will especially focus on a member of the SERCA family, SERCA3, recently found to give rise to a number of species-specific isoforms. Next, we will describe the differences in Ca(2+)ATPase patterns observed in human and rat platelets. Last, we will analyze how the expression of Ca(2+)ATPase isoforms changes during megakaryocytic maturation and show that megakaryocytopoiesis is associated with a profound reorganization of the expression and/or activity of Ca(2+)ATPases. Taken together, these data provide new aspects of investigations to better understand normal and abnormal platelet Ca(2+) signaling.

Animals↗
PubMedDate not supplied

The estrogen responsive element of the pS2 gene is recognized by a methylation sensitive DNA binding protein.

The human pS2 gene is specifically expressed is a subclass of estrogen receptor containing human breast cancer cells. In the MCF7 cell line, its induction by estradiol is a primary transcriptional event. The exact location of its estrogen responsive element has been determined using a chimeric recombinant transfected into HeLa cells and a transient expression assay. In this study we found, using electrophoretic mobility shift experiments, that in HeLa cells the estrogen responsive element (ERE) of the pS2 gene is recognized by a methylation sensitive DNA binding protein (MSDBP) different from the estrogen receptor. Competition experiments have shown that the binding of this protein requires at least one CpG in the center of the palindromic sequence and that imperfect palindromic sequences are also recognized. Although the presence of CpG is necessary, CpG-rich oligonucleotides, containing consensus sequences for Sp1 or AP2, do not interfere with its binding to the pS2 oligonucleotide, indicating that the ERE sequence itself participates in the specificity of its binding. This protein binds the pS2 sequence with a relatively high affinity (apparent Kd = 10(-10) M) and its binding is strongly reduced by the methylation of the cytosines at CpG sites. UV cross-linking experiments and peptide mapping indicate that this protein has an apparent molecular weight of 46 kDa and is present in several cell lines, including non-human cell lines. Taken together, these data suggest that this protein might have a potential role in regulating gene activity or in chromatin structure of some genes possessing an ERE.

Animals↗
PubMedDate not supplied

Planning for change.

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Health Care Reform↗
PubMedDate not supplied

Managing transition. 1.

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Adaptation, Psychological↗
PubMedDate not supplied

Managing transition: 2.

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Adaptation, Psychological↗
PubMedDate not supplied

Enduring negative psychological characteristics of male and female step-children toward the step-parent.

Many divorced people remarry, and if either one or both of the remarried partners has a child or children from a former marriage, then the youth need adjust to not only the new marital structure, but to the new step-parent as well. The present research was conducted to determine: (1) enduring negative psychological characteristics of male and female step-children toward the step-parent, and (2) a comparison of the similarities and/or differences of each. Results suggested ten of the most frequently stated variables of both subject groups, similarities or significant differences between them by subject status, and their relevancy to the step-child-step-parent relationship.

Adaptation, Psychological↗
PubMedDate not supplied

MR imaging of acute spinal cord injury: results of an experimental study in dogs.

A weight-drop model was used to induce 16 acute lesions of varying severity in the spinal cords of eight mongrel dogs. The subsequent 3- to 7-hr postinjury MR images (0.5 T) were assessed. T1-weighted images contributed little information. Injection of gadolinium tetra-azacyclododecane tetraacetic acid did not result in significant enhancement. T2-weighted sequences offered precise detection and delineation of the lesions, displaying fusiform hyperintense signal abnormalities that corresponded to both edema and hemorrhage. In low-impact injuries, abnormalities were small and centrally located, sparing the periphery of the spinal cord. In these cases hemorrhage was minimal and limited to the center of the lesion. In severe-impact injuries, MR showed widespread longitudinal extension with involvement of the periphery of the spinal cord. In the most severe injuries, a central heterogeneous signal component was frequently observed opposite the site of impact because of important hemorrhage within the cord. Overall, hyperintense areas correlated closely with lesion severity, as demonstrated by pathologic findings. T2-weighted MR images obtained at 0.5 T were found to be reliable in the evaluation of acute spinal cord trauma.

Animals↗