On the propagation of a disturbance through a viscous liquid flowing in a distensible tube of appreciable mass

The velocity of propagation of a disturbance wave in a liquid flowing in a distensible tube is computed. The mathematical model is more general than those used in previous analyses: the tube wall properties are realistic; the convective part of the axial inertia forces is taken into account; radial inertia forces of both the fluid and tube wall are present; viscous stresses are present. Four parameters influencing the velocity of propagation are obtained and discussed. Curves are plotted illustrating the effects of the parameters. Contrary to the results of previous analyses, viscous effects are shown to be appreciable in blood flow. It is also shown that radial inertia effects can be important in laboratory set-ups. The material presented in this paper was adapted from the Ph.D. thesis written by the author at Harvard University.     

Structural chromosome abnormalities in Down syndrome: a study of two families.

Two families were ascertained through a proband with Down syndrome and a structural rearrangement involving two chromosomes 21. It is suggested that in one patient the chromosome is an isochromosome formed by misdivision of the centromere of a maternal telocentric chromosome 21 and that in the other a Robertsonian translocation involving chromosome 21 was inherited from the mother, who is a 46,XX/46,XX, -21,+t(21q21q) mosaic. The origin of the mosaicism is discussed and considered to be likely to be the result of breakage and reunion at the chromatid, rather than the chromosome, level.     

THE ROLE OF CARBONIC ANHYDRASE IN CERTAIN IONIC EXCHANGES INVOLVING THE ERYTHROCYTE

1. The acceleration by bicarbonates of the swelling and hemolysis of erythrocytes in solutions of ammonium salts, first reported by Ørskov, is strikingly dependent upon carbonic anhydrase, being almost abolished by inhibitors of this enzyme such as KCN and sulfanilamide, and under suitable conditions being enhanced by its addition to the external solution. This behavior gives support to the theory of "catalyzed diffusion" as an explanation of the Ørskov effect. 2. The inhibitory effects of both sulfanilamide and KCN seem to be capable of complete reversal on washing the erythrocytes in isotonic salt solutions. The full effect of KCN appears almost instantly; that of sulfanilamide requires a period measured in seconds, or possibly even in minutes, to reach its maximum, the delay presumably being due to the slower penetration of the erythrocyte by this substance. Under favorable conditions the effect of concentrations of sulfanilamide of a few hundredths of a milligram per cent can be demonstrated. No similar effects have been obtained with sulfapyridine. 3. Bicarbonates also have a "catalytic" effect on the response of the internal pH of erythrocytes to changes in that of their surroundings. The resulting volume changes of the cell, which otherwise frequently require many minutes for their completion, may take place within a few seconds in the presence of low concentrations of bicarbonates. At a given pH value the effect of the latter substances is chiefly on the rate of the change and only to a minor extent on its magnitude. It may be further accelerated under appropriate conditions by the addition to the cell suspension of carbonic anhydrase, and can be almost abolished by KCN and by sulfanilamide. 4. Volume changes of erythrocytes associated with exchanges of Cl'' for SO₄'''' ions are greatly accelerated by low concentrations of bicarbonates, this effect being likewise dependent upon carbonic anhydrase. There is some evidence that in this case the exchange takes place, at least in part, in two steps: Cl'' for HCO₃'' and HCO₃'' for SO₄''''.     

Estimation of hormone receptor affinity by competitive displacement of labeled ligand: effect of concentration of receptor and of labeled ligand.

Ferrichrome is shown to compete in vitro for the partially purified outer membrane phage T5 receptor complex of Escherichia coli K-12. Among siderochromes tested the competition is confined to ferrichrome and its analogs. Thus reversal of receptor inhibition of plaque formation is achieved by ferrichrome, ferricrocin, and the aluminum and chromium(III) derivatives of deferriferrichrome but not by rhodotorulic acid, Desferal, or ferrichrome A.     

Influence of serum luteinising hormone concentrations on ovulation,conception, and early pregnancy loss in polycystic ovary syndrome.

Women with the polycystic ovary syndrome do not respond well to treatment with luteinising hormone releasing hormone. To determine whether this might be due to an underlying endocrine disturbance basal concentrations of luteinising hormone were measured in 54 infertile women treated with pulsatile luteinising hormone releasing hormone and concentrations at the time of maximum follicular growth were measured in 23 of the patients. Forty one patients ovulated. Forty one patients ovulated and 27 conceived, but nine pregnancies terminated within four weeks after ovulation. Basal luteinising hormone concentrations were significantly lower in those who conceived (12.4 (range 1.3-29.0) IU/l) than in those who did not (19.0 (3.5-50.0) IU/l) and in those whose pregnancy progressed (9.6 (1.3-29.0) IU/l) than in those with early loss of pregnancy (17.9 (7.0-29.0) IU/l). Concentrations at the time of maximum follicular growth were significantly lower in women who ovulated (9.4 (2.9-35.4) IU/l) than in those who did not (29.0 (7.0-50.0) IU/l) and in those who conceived (6.2 (2.9-8.5) IU/l) than in those who did not (17.9 (4.0-50.0) IU/l). These results indicate that high concentrations of luteinising hormone during the follicular phase in women with polycystic ovaries have a deleterious effect on rates of conception and may be a causal factor in early pregnancy loss.     

Structure-based design and parallel synthesis of N-benzyl isatin oximes as JNK3 MAP kinase inhibitors

A series of N-benzylated isatin oximes were developed as inhibitors of the mitogen-activated kinase, JNK3. X-ray crystallographic structures aided in the design and synthesis of novel, selective compounds, that inhibit JNK3, but not p38 MAP kinase and provided key insights into understanding the behavior of gatekeeper residue methionine-146 in determining target selectivity for this series.