PubMed Health⌕ Search

Biomedical subjects

Y Hoffman

Publications and source records attributed to Y Hoffman.

11 recordsLinked to original sources
PubMed2000

Goodness-of-Fit Analysis of Radial Velocity Surveys.

Using eigenmode expansion of the Mark III and SFI surveys of cosmological radial velocities, a goodness-of-fit analysis is applied on a mode-by-mode basis. This differential analysis complements the Bayesian maximum likelihood analysis that finds the most probable model given the data. Analyzing the surveys with their corresponding most likely models from the CMB-like family of models, as well as with the currently popular LambdaCDM model, reveals a systematic inconsistency of the data with these "best" models. There is a systematic trend of the cumulative chi(2) to increase with the mode number (where the modes are sorted by decreasing order of the eigenvalues). This corresponds to a decrease of the chi(2) with the variance associated with a mode and hence with its effective scale. It follows that the differential analysis finds that on small (large) scales the global analysis of all the modes "puts" less (more) power than actually required by the data. This observed trend might indicate one of the following: (1) the theoretical model (i.e., power spectrum) or the error model (or both) have an excess of power on large scales, (2) velocity bias, or (3) the velocity data suffers from systematic errors that have not yet been corrected.

Journal Article↗
PubMed1995

Wheeling and healing.

There's a new road company touring Southeast Michigan with a never-before-seen act! Their costumes are all in white, their set and props elaborate, and they actually perform inside a truck! Get this--they're not actors. They're doctors. And these doctors from Mount Clemens General Hospital have gotten their facts together and are taking their show on the road.

Community Health Services↗
PubMed1993

Abnormal fibrillin metabolism in bovine Marfan syndrome.

Bovine Marfan syndrome is a disorder that closely resembles human Marfan syndrome in its clinical signs and pathological lesions. The similarities between the human and bovine diseases suggest that similar metabolic defects could be responsible. Although indirect immunofluorescent assays for fibrillin in skin biopsies did not distinguish affected cattle from control animals, cultures of skin fibroblasts of affected animals were distinguished from normal, unrelated control animals and normal half-siblings on the basis of fibrillin staining. After 72 to 96 hours in culture, stained with anti-fibrillin monoclonal antibody 201, hyperconfluent fibroblast cultures of affected cattle had less immunoreactive fibrillin than control cultures, and the staining pattern was granular rather than fibrillar. Under similar culture conditions, normal bovine aortic smooth muscle cells produced large amounts of immunoreactive fibrillin, but smooth muscle cells from a single affected cow showed markedly less fibrillin staining. In pulse-chase metabolic labeling experiments with [35S]cysteine, dermal fibroblasts from 6 affected calves, incorporated far less fibrillin into the extracellular matrix than control cells. These findings are similar to those reported in human Marfan syndrome, and they suggest that the bovine Marfan syndrome, like the human disorder, is caused by a mutation in fibrillin, leading to defective microfibrillar synthesis.

Animals↗
PubMed1992

Normal elastin content of aorta in bovine Marfan syndrome.

Samples from the ascending aortae from two calves affected by bovine Marfan syndrome were subjected to biochemical analyses of the connective tissue and were compared to age-matched controls. Elastin was extracted from the aortic samples with 5 M guanidine-HCl, bacterial collagenase digestion, and dithiothreitol reduction. Amino acid analysis revealed that desmosine and isodesmosine levels were the same in Marfan calves as in control animals. Gravimetric measurements of elastin, amino acid composition, soluble protein, and uronic acid values also showed no significant difference between Marfan and control tissue. In contrast to elastin, collagen in aortae of Marfan calves was significantly higher than the mean of several controls. These findings, along with other observations of this animal model, support the conclusion that the microscopic and biochemical lesions of aortic elastin in bovine Marfan syndrome likely result from defective microfibrillar metabolism. Absence of cystic medial necrosis in bovine Marfan aortae may explain normal elastin content in the animal model.

Animals↗
PubMed1991

Multiple components of a complex androgen-dependent enhancer.

Sex-limited protein (Slp) is expressed in adult male mice. A 160-basepair fragment 2 kilobases upstream of the gene serves as an androgen-dependent enhancer of chloramphenicol acetyltransferase expression in transient transfection assays in cells with endogenous or cotransfected androgen receptor. One element that is necessary, but not sufficient, for induction is a consensus glucocorticoid (or hormone) response element (HRE). This element binds to the mouse androgen receptor in vitro, but with apparent weak affinity. Induction by the HRE is greatly augmented by an accessory sequence within the 160 basepairs, suggesting that cooperative interactions confer strong response to androgen. Additional elements within the enhancer modulate induction, positively or negatively, and exhibit cell-specific behavior. Of particular interest are two degenerate HREs that are adjacent to the consensus sequence; they show no independent activity, but are functionally significant in conjunction with other elements. The complexity of this enhancer may reflect biological mechanisms that ensure specificity of hormonal response and allow gene expression to respond to changes in hormone concentration.

Animals↗
PubMed1982

Adenohypophyseal cytology of chemically and surgically thyroidectomized cockerels.

Reproductive traits and histology of the adenohypophysis were studied in adult White Leghorn cockerels after surgical thyroidectomy or .1% propylthiouracil (PTU) food supplementation. Both treatments caused hypothyroidism as judged by a marked reduction in plasma thyroxine levels, a decrease in resting metabolic rate values, an increase in liver and adipose tissue weights, and a marked elevation in the alcianophilic cell population in the adenohypophysis. Both the PTU-treated and thyroidectomized birds demonstrated reduced testes and comb weights. However, although thyroidectomy was found to increase the number of PAS-positive cells in the adenohypophysis, the PTU treatment reduced them. This phenomena is discussed.

Animals↗