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Biomedical subjects

J G Baldwin

Publications and source records attributed to J G Baldwin.

10 recordsLinked to original sources
PubMed1998

Buccal capsule development as a consideration for phylogenetic analysis of Rhabditida (Nemata).

Bacterial feeding nematodes in the order Rhabditida including Zeldia punctata (Cephalobidae) and Caenorhabditis elegans (Rhabditidae) differ profoundly in the buccal capsule parts and associated cells. We carried out a range of tests to determine which buccal capsule parts and cells are evolutionarily homologous between the representative species of the two families. Tests included reconstruction of the buccal capsule and procorpus with transmission electron microscopy (TEM), nuclei position and morphology using 4, 6-diamidino-2-phenylindole (DAPI) staining, and cell lineage using four dimensional (4D) microscopy. The lining of the buccal capsule of Z. punctata and additional Cephalobidae includes four sets of muscular radial cells, ma, mb, mc and md, in contrast to C. elegans and additional Rhabditidae, which has two sets of epithelial cells (e1, e3) and two sets of muscle cells (m1, m2). Cell lineage of a nematode closely related to Z. punctata, Cephalobus cubaensis, supports the hypothesis that in cephalobids the e1 and e3 cells become hypodermal cells or are programmed to die. Our findings contradict all previous hypotheses of buccal capsule homology, and suggest instead that ma and mb in Z. punctata are homologous to m1 and m2 in C. elegans respectively. We also hypothesize that ma and mb could be homologous to primary and secondary sets of stylet-protractor muscle cells in the plant parasitic Tylenchida.

Animals↗
PubMed1997

An evolutionary framework for the study of developmental evolution in a set of nematodes related to Caenorhabditis elegans.

Nematodes are known to be a useful system for studies of comparative development. Here we perform a molecular phylogenetic analysis to allow for the independent interpretation of the developmental and morphological changes observed among a selected set of nematode species. Our molecular phylogenetic analysis is based on coding regions of the genes for RNA polymerase II, the small subunit rRNA and an expansion segment of the large subunit rRNA. Sequences were compared from five species in the family (Rhabditidae) that includes the developmental model organism Caenorhabditis elegans and from an outgroup taxon Aduncospiculum halicti (Diplogasterina). The phylogenetic analysis does not support the monophyly of the subfamily Mesorhabditinae and identifies the unnamed strain PS1010 as a sister taxon of C. elegans despite its morphologically divergent buccal capsule. On the basis of the inferred framework, we can begin to interpret the evolution of vulval development and of morphological differences among these nematode species.

Animals↗
PubMed1989

Profound thrombocytosis in a patient with iron-lack anemia.

Platelet counts in excess of 1 million/cu mm are generally associated with a primary hematologic disorder such as a myeloproliferative syndrome. We describe a patient whose thrombocytosis (platelet count 1.6 million) was due solely to iron lack, and whose platelet count rapidly returned to normal with iron repletion. Clinicians are encouraged to consider reactive causes of thrombocytosis when evaluating platelet counts in excess of 1 million.

Anemia, Hypochromic↗
PubMed1989

True anemia: incidence and significance in the elderly.

The incidence of anemia increases as humans age, but in healthy aging individuals followed longitudinally, significant anemia does not develop in the absence of disease. Mild lymphopenia, as well as abnormal platelet function tests and increased coagulability when measured in vitro, also tend to develop in aging individuals. Hematologic neoplasia in the elderly behaves very similarly to the way it does in young individuals, but elderly individuals with hematologic neoplasms have a poor response to therapy.

Aged↗
PubMed1988

Hematopoietic function in the elderly.

Very little information is available on the effect of aging on human bone marrow function. In reviewing both murine and human studies on bone marrow function in the elderly, it may be concluded at present that there is an increasing incidence of anemia that develops with aging in humans. Extensive animal and limited human data support decreased marrow reserve capacity with decreased hormonal responsiveness to hematologic stress as the most likely cause. In normal human life spans, marrow stem cells do not appear to wear out, and, finally, clinicians are cautioned not to attribute anemia per se simply to aging. Any elderly individual with unexplained anemia must be fully evaluated for the possibility of occult gastrointestinal blood loss, marrow failure syndrome, or hemolytic state before his/her anemia is attributed to age alone. Much additional research remains to be done on hematopoietic function in aged individuals.

Aging↗
PubMed1978

Myxedema coma and normal serum thyroxine.

A 76-year-old man who developed the clinical syndrome of myxedema coma was found to have a normal serum thyroxine concentration. Further investigation revealed the presence of a low serum T3 level before and after sodium levothyroxine therapy when the serum T4 value was in the hyperthyroid range. In addition, he demonstrated an inability to release TSH after intravenous administration of TRH and was found to have an enlarged sella turcica. A partial defect in peripheral conversion of T4 to T3 is postulated.

Aged↗