An outcrossed canine pedigree for linkage analysis of hip dysplasia

Twenty-four hip replacements were performed with use of a medial protrusio technique to stabilize the fit of a hemispherical metal shell in the acetabulum in nineteen patients who had dysplasia of the hip. All of the hips were followed for a minimum of five years (average, seven years; range, five to thirteen years). Six of the hips were type I, seven were type II, eight were type III, and three were type IV according to the criteria of Crowe et al. The acetabular cup was implanted with the medial aspect of its dome beyond the Kohler line (drawn from the ischium along the ilioischial line) in all hips. An autogenous graft sculpted from the femoral head was used to cover 15 to 30 percent of the superolateral portion of the cup in one type-I hip, four type-III hips, and one type-IV hip. The need for these six bone grafts could have been avoided by reaming two to three millimeters more medially or by allowing 20 percent of the superolateral portion of the cup to be uncovered. Sixty to 84 percent of each bone graft was resorbed, effectively leaving the superolateral portion of the cup uncovered. The amount of the surface of the cup that was beyond the Kohler line averaged 41 percent for the six type-I hips, 43 percent for the seven type-II hips, 41 percent for six of the type-III hips, and 44 percent for one of the type-IV hips. Crossing of the ilioischial and iliopubic lines was noted on the radiographs of two type-III and two type-IV hips. Radiographs of two type-I hips and one type-II hip showed 7 to 17 percent of the surface of the dome of the cup through the internal pelvic wall (beyond the iliopubic line). None of the twenty-four metal shells were revised. A reoperation was performed on two hips to exchange a worn polyethylene insert, and three femoral components that had been fixed without cement were revised because of mechanical loosening. Wear averaged 0.26 millimeter per year in the fourteen hips that had a titanium femoral head and 0.09 millimeter per year in the nine hips that had a cobalt-chromium femoral head. The remaining hip had a ceramic femoral head, and the wear rate was 0.09 millimeter per year. The medial protrusio technique is a predictable, reproducible method for obtaining fixation of a porous-coated, hemispherical acetabular component in a dysplastic acetabulum. The technique permits the use of a porous-coated (bone-ingrowth) component; avoids the use of support bone graft and thereby reduces the operative time; facilitates rehabilitation by permitting earlier weight-bearing of the hip; and permits the use of a modular bearing surface, which may allow future exchange of only this surface rather than revision of the entire acetabular component because of excessive wear.     

Hypercholesterolemia and aortic collagen synthesis in rabbit aortas

Male adult New Zealand rabbits were fed a 2% cholesterol diet for 30 of 60 days in order to determine the effect of hypercholesterolemia on aortic collagen synthesis. Collagen synthetic activity was estimated by measuring tissue prolyl hydroxylase activity and the amount of tissue collagen was estimated by measuring tissue hydroxyproline levels. Following 30 or 60 days of feeding there was a significant increase in both tissue and serum cholesterol indicating the onset of hypercholesterolemia. Measurement of collagen synthetic activity and tissue collagen levels demonstrated no increase over control tissues. These data therefore indicate that hypercholesterolemia is not a direct stimulus of tissue collagen synthetic activity.     

The subunit structure of alpha-acetohydroxyacid isomeroreductase from Salmonella typhimurium

Alpha-Acetohydroxyacid isomeroreductase from Salmonella typhimurium has a native molecular weight of 220,000. The constituent polypeptide chains exhibit anomalous but unimodal electrophoretic migration on sodium dodecyl sulfate-urea polyacrylamide gels. The subunit molecular weight, determined by sedimentation equilibrium in 6 M guanidine hydrochloride, is 57,000. The apparent tetrameric nature of the native enzyme was confirmed by determining the types of oligomers formed upon cross-linking with dimethylsebacimidate. Analysis of tryptic peptides suggests that the polypeptide chains have an identical amino acid sequence. Carbohydrate analysis, ultraviolet absorption spectrum, and atomic absorption spectrum are consistent with the lack of cobalamine and cobalt. The Michaelis constants are as follows: alpha-acetolactate, 2.9 x 10-4 M; alpha-aceto-alpha-hydroxybutyrate, 7.8 x 10-4 M; NADPH, 1.5 x 10-5 M; Mg2+, 7.7 x 10-4 M. The catalytic constants (molecules of substrate catalyzed per min per molecules of enzyme) for alpha-acetolactate and alpha-aceto-alpha-hydroxybutyrate are 1,100 and 4,700, respectively. Comparative tryptic peptide analysis and immunological analysis show that alpha-acetohydroxyacid isomero-reductase and biosynthetic L-threonine deaminase bear no structural relationship and therefore rule out a "shared structure" hypothesis for the putative involvement of L-threonine deaminase in the synthesis of alpha-acetohydroxyacid isomeroreductase.     

Osmolality of equine blastocyst fluid from day 11 to day 25 of pregnancy

Horse conceptuses collected between Day 11 and Day 18 of pregnancy float in isotonic media. To investigate this phenomenon, blastocyst fluids from 30 conceptuses from 13 mares were analysed for osmolality and for concentrations of Na+, Cl-, K+, glucose, urea and creatinine. In conceptuses from Group A, samples from Day 11 to Day 16 yielded the following results (mean +/- s.e.m.): osmolality, 121.4 +/- 1.5 mOsm kg-1; Na+, 11.0 +/- 2.2 mM; Cl-, 29.3 +/- 2.5 mM; K+, 26.2 +/- 2.6 mM; glucose, 0.6 +/- 0.1 mM; urea, 6.0 +/- 0.6 mM; creatinine, 9.6 +/- 1.1 microM. Between Day 16 and Day 25, the osmolalities and Na+ concentrations increased gradually with age but the former never exceeded 255 mOsm kg-1. Fluids from Group B were obtained from eight conceptuses exposed to saline solutions of different osmolalities for various periods of time. An increased perivitelline space of 1-3 mm became evident at the lower pole of the floating conceptus after 45 min of exposure to solutions with osmolalities of > or = 300 mOsm kg-1, suggesting that Na+ and Cl- diffuse freely through the capsule but not through the trophoblast. The significance of the hypo-osmolality of equine blastocyst fluid is discussed but remains unclear.