Search PubMed⌕ Search

Biomedical subjects

M S Lin

Publications and source records attributed to M S Lin.

At least 91 records · Page 5Linked to original sources
PubMed1988

DA/DAPI-fluorescent heteromorphism of human Y chromosome.

Variation of DA/DAPI intensity in the Yq12 band was observed in five amniotic cell specimens and one blood specimen from the father of one fetus. Three distinct classes of Yq heterochromatin were identified by distamycin A (DA) treatment of the cell cultures and various staining techniques. The heterochromatin in the Yq11.23 sub-band does not undercondense when exposed to DA, and shows pale fluorescence with quinacrine staining, positive C-banding, and bright fluorescence with DA/DAPI technique. This class of heterochromatin was consistently observed in all specimens studied. The other two classes of heterochromatin are in the Yq12 band. Both show undercondensation when exposed to DA, quinacrine-bright fluorescence, and positive C-banding; however, one class of heterochromatin shows DA/DAPI-bright fluorescence and the other shows pale fluorescence. The size and banding intensity of the two classes of heterochromatin in Yq12 are variable. These results provide cytological evidence of heterogeneity within the Y heterochromatin region containing AT-rich DNA.

Chromosome Banding↗
PubMed1988

Lack of effects of calcium antagonists on red blood cell deformability in hypertension.

To compare the red blood cell (RBC) deformability in hypertensive patients and healthy volunteers and to evaluate the effects of calcium antagonists on RBC deformability in hypertension, forty mild-to-moderate hypertensive patients and forty healthy volunteers, matched for age, sex and smoking habits, were studied. Each patient was randomized to receive one of the four following two-week treatment regimens: nifedipine 10 mg, verapamil 80 mg and diltiazem 60 mg three times a day and no drug. RBC deformability, measured with a gravity driven filtration technique, and mean arterial pressure were determined before and after the treatment. No difference in RBC deformability was observed between hypertensive patients and healthy volunteers. In contrast to the significant reduction in mean arterial pressure, RBC deformability was not altered by any of the three calcium antagonists. We conclude that a two-week treatment with calcium antagonist, at the effective vasodepressor dose, has no effect on RBC deformability in mild-to-moderate hypertensive patients.

Adult↗
PubMed1988

Roberts syndrome.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1987

Expression of fragile X in human-mouse somatic cell hybrids.

Fragile X expression was studied in human-mouse cell hybrids prepared from lymphocytes and fibroblasts obtained from a mentally retarded male. The patient showed a fragile X in 29-35.5% of his lymphocytes in medium 199 (M199) and in M199 plus fluorodeoxyuridine (FdU). One lymphocyte hybrid clone showed no expression in M199 and low expression in M199 + FdU. The other lymphocyte hybrid clone showed significantly increased expression in both media, comparable to levels in the parental cells. Fibroblast cultures from the patient showed no fragile X expression in M199 and 17% expression in M199 + FdU. Fragile X expression was also found in fibroblast hybrid clones in M199 and was significantly enhanced by the addition of FdU. Fragile X expression in one clone was consistently lower than in the other two clones and in the parental fibroblasts. Our results indicate that the level of fragile X expression varies in the hybrid clones, since frequencies similar to those of parental cells and suppressed frequencies were found. The presence or absence of a specific human chromosome did not correlate with the level of fragile X expression.

Animals↗
PubMed1987

Effect of C-banded heterochromatin on centromere separation.

The present study is to determine the effects of centromeric heterochromatin on centromere separation. Amniotic cell cultures in which the centromeric heterochromatin of one chromosome was at least twice as large (qh+) as the heterochromatin (qh) in the homologous chromosome were selected. Fifteen amniotic cell samples with 1qh+, 9qh+ or 16qh+ were studied. The size of the centromeric heterochromatin was directly correlated with the delay in centromere separation. The chromosome with the smaller centromeric heterochromatin tended to show earlier centromere separation than the homologue with the larger heterochromatin. Our results suggest that the quantity of centromeric heterochromatin may influence the genetic control of centromere separation.

Amnion↗
PubMed1987

Prazosin-induced first-dose phenomenon possibly associated with hemorrhagic stroke: a report of three cases.

A small initial dose of prazosin ranging from 0.5 to 1 mg has been recommended to avoid the first-dose phenomenon characterized by a sudden and severe drop in blood pressure after the administration of the first dose of prazosin. However, even with an initial dose of 0.5 mg, hypotension with consciousness disturbance developed in three hypertensive patients with recent cerebral hemorrhage. We present this report to alert physicians and pharmacists about the potential risk of the first-dose phenomenon even at the recommended initial doses of prazosin in hypertensive patients who have suffered a recent stroke.

Cerebral Hemorrhage↗
PubMed1986

Two-point T1 measurement: wide-coverage optimizations by stochastic simulations.

Stochastic reliability of T1 measurement from image signal ratios is examined in the ideal case by stochastic simulations in the context of wide-coverage optimizations. Precise measurements prove to be accurate, and accurate ones precise. Sign-preserved inversion-recovery (IR)/non-IR techniques are the best ratio method, reciprocal non-IR/IR ones being equivalent, but inconvenient. Wide-coverage optima are relatively unsharp. Suggested guidelines for covering the 150- to 1500-ms T1 band are minimal relevant TE; TI about 400 ms; effective repetition times about in the ratio, TR2(IR)/TR1 (non-IR) = 2.5-3.0, and in a sum as long as possible up to about TR1 + TR2 = 3.5-4.0 s; signal-averaging after and only after TR1 + TR2 has been lengthened to the said region. Also suggested are different guidelines for covering T1 bands, 120-1200 and 200-1800 ms. Typically, precisions and accuracies improve linearly or faster with increasing S/N and (S/N)2, respectively. Unnecessarily high pixel resolutions or thin slicings exact great penalties in accuracies. Progressively shortening TR1 eventually transforms a wide coverage into a sharp targeting with small potential gains in a narrow T1 locality and large compromises almost everywhere else. The simulations yield an insight into applicabilities of standard error propagation analyses in two-point T1 measurement.

Biometry↗
PubMed1986

Numerical T1 computation from NMR intensity ratios.

Two-point measurement of tissue T1 from NMR intensity ratios consists of forming an a priori ratio function describing a T1 dependence of the ratio R(T1) and computing T1 from an observed ratio Q by numerically solving R(T1)-Q = 0 or an equivalent equation. Impact of R(T1) designs on the numerical computation and dependence of relative speeds of three numerical methods on desired computational precisions q and on other factors are examined. All three methods begin with computing a table of R(T1) entries in uniform T1 steps (delta T1). In two iterative methods, a step containing the T1 root is looked up, and the precise T1 location within the step is pinpointed to within a q value by either linear-interpolative (LI) or Newton-Raphson (NR) iteration. The third method simply consists of computing a large table of delta T1 = q for a mere "look-up" with no iterative search. All three methods require a monotonous R(T1) for uniformly effective computation over wide T1 ranges. Speeds of either iterative method for computing T1 images are expected to vary with delta T1 and q with unsharp speed maxima at delta T1 near 20, 6, and 2 ms for q = 10(-1), 10(-2), and 10(-3) ms, respectively. Either iterative method is suitable for both low- and high-precision computations, the LI method being generally faster. The simple look-up is the fastest of the three for T1 image computation to low precisions of q greater than or equal to 1 ms, is likely the slowest for that to q = 0.1 ms, and is impractical for that to q less than or equal to 0.01 ms.

Algorithms↗