Dependence of electrical conductivity on fixed charge density in articular cartilage

A new system for measuring the resistivity of articular cartilage is based on the four-point probe technique. The system measures resistivity as a function of depth from the articular surface. The measurements obtained showed that the conductivity, kappa, of articular cartilage equilibrated in Ringer's solution (pH, 7.4) is constant in all zones, with a value of 6-10 X 10(-3) mho/cm. Conversely, kappa of articular cartilage equilibrated in distilled water varies distinctly, being low in the superficial zone (about 0.7 X 10(-3) mho/cm) and high in the middle to deep zone (about 3 X 10(-3) mho/cm). This is almost the same variation shown by the fixed charge density, FCD, which was measured by the tracer cation method; a linear correlation between kappa and the FCD was found (correlation coefficient, 0.88). These observations were well understood based on the Donnan equilibrium; the mobility of Na+ in cartilage was thought to be independent of FCD.

Mitral valve prolapse in five members of a family including the identical twins

A family in which the five members including the identical twins had a mitral valve prolapse was described. None of these members had any known stigmata of Marfan syndrome and their auscultatory findings were different each other. M-mode echocardiograms disclosed a midsystolic buckling of the mitral valve in the identical twins, their parents and the mother's brother, but all were asymptomatic. Electrocardiograms revealed a wandering pacemaker in two members. The index case was a 13-year-old girl whose apical late systolic murmur was detected incidentally by the mass screening examination for cardiac diseases. Both the inhalation of amyl nitrite and injection of methoxamine induced the augmentation of this murmur and made it holosystolic. The identical twin of the index case had multiple apical non-ejection clicks. However, a mitral regurgitant murmur was not induced by pharmacological provocations. Two-dimensional echocardiograms revealed prolapse of both the anterior and posterior mitral valve leaflets in both of them. Their mother had a late systolic click and the mother's brother had a cardiopulmonary murmur. The abnormal auscultatory findings were not observed in their father. This familial study suggested the genetic background and the various clinical manifestations of mitral valve prolapse.

A rare phenotype of phosphoglucomutase-2 first detected in Mongoloids

In screening of the PGM system by isoelectric focusing a heterozygote with a rare allele of PGM2 was detected. Family studies and family register checkings for the propositus showed evidence of hereditary occurrence of this allele, and all the ancestors of the propositus were Japanese. Although there have been no reports among Mongoloids, the variant found in the present study is likely to be the first case of a rare phenotype of PGM2 among such populations. In addition, isoelectric focusing data on 411 Japanese samples are given.

Studies of diacylglycerol cholinephosphotransferase and diacylglycerol ethanolaminephosphotransferase activities in Tetrahymena microsomes

Microsomes isolated from Tetrahymena pyriformis synthesized phosphatidylcholine and phosphatidylethanolamine by CDPcholine: 1,2-diacylglycerol cholinephosphotransferase (EC 2.7.8.2) and CDPethanolamine: 1,2-diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1), utilizing ethanol-dispersed dioleoglycerol. Cholinephosphotransferase and ethanolaminephosphotransferase activities have similar dependences on MgCl2 and MnCl2, but the latter was more effective than the former for both enzyme activities. The V values for 1,2-dioleoylglycerol obtained at optimal conditions were 1.8 nmol/min per mg microsomal protein for cholinephosphotransferase and 0.6 nmol/min per mg microsomal protein for ethanolaminephosphotransferase. Both enzymes could not utilize 1,3-dioleoylglycerol or 1-oleoylglycerol as substrates. Cholinephosphotransferase had an apparent Km for CDPcholine of 11.7 microM with 1,2-dioleoylglycerol and was inhibited by CDPethanolamine competitively. On the other hand, ethanolaminephosphotransferase has an apparent Km for CDPethanolamine of 8 microM and CDPcholine was a noncompetitive inhibitor of ethanolaminephosphotransferase activity. Furthermore, despite the marked alteration of phospholipid composition occurring during the temperature acclimation of Tetrahymena cells, both enzyme activities showed similar dependences on growth and incubation temperatures. This may imply that the final step of de novo synthesis of two major phospholipids does not participate in the thermally induced modification of the profile of phospholipid polar head group in membranes.

Erythrocyte membrane abnormalities in experimental biliary obstruction: comparative studies on erythrocyte membranes from rats with intra- and extrahepatic cholestasis

The red blood cells from rats with intra- and extrahepatic cholestasis obtained by feeding of alpha-naphthylisothiocyanate (ANIT) and ligation of bile duct, respectively, were analysed from biochemical as well as ultrastructural point of view. A significant increase of cholesterol content was observed in the red cell membrane from bile duct-ligated rat. An increment of absolute lecithin content without accompanied increase in phospholipid content was observed in both groups. The fatty acyl chain composition of lecithin remained unchanged except a small increase in stearic acid (13.0% leads to 18.1%) in the bile duct-ligated rat. Despite a small change in the lipid composition, scanning electron microscopic observation revealed a profound alteration in red cell ultrastructure; most of cells were in spur type in ANIT-fed group while variations in red cell shape were observed in bile duct-ligated group.

Mechanism for lipid abnormalities of erythrocyte membranes in biliary obstruction: lecithin content and its fatty acyl composition

The lipid compositions of erythrocyte membranes, plasma and bile of 16 patients with biliary obstruction were analysed to obtain information regarding the origin of excess lecithin which is usually found in the erythrocyte membranes in obstructive jaundice. Phospholipids and free cholesterol were found to be increased proportionally to the degree of biliary obstruction with an elevation in the free cholesterol/phospholipid ratio in the red cell membranes. The increase in phospholipid content is primarily due to lecithin. There was a highly significant alteration in the fatty acid composition of lecithin of erythrocyte membranes, plasma and bile from patients with severe jaundice. Red cell membrane lecithin amounted to more than 40% of the total phospholipid in these patients. Interestingly, the fatty acid composition of lecithin showed a similar pattern in erythrocyte membranes, plasma and bile. In addition, the fatty acyl chain composition of lecithin in lipoprotein-X was very similar to that of the red cell membrane. Freeze-fracture electron microscopy showed an alteration in membrane morphology and a reduced number of membrane-associated particles in the fractured faces. From these findings, we suggest that the lecithin of lipoprotein-X is derived from abnormal bile lecithin, which is incorporated into erythrocyte membranes by fusion with lipoprotein-X. On the other hand, the fatty acid composition of bile lecithin from patients with mild jaundice, whose erythrocyte membrane lecithin amounted to less than 31% of total phospholipid, was not different from that of normal individuals. However, in sharp contrast to the bile content, the fatty acid composition of erythrocyte membranes and plasma in these same patients showed a similar but small change compared to that of patients with severe biliary obstruction. The red cells of patients with mild jaundice were almost normal, biconcave disc-shaped, as observed by scanning electron microscopy and no abnormalities in the distribution or number of membrane particles were detected by freeze-fracturing. We propose that the abnormal lecithin content of erythrocyte membranes in patients with mild jaundice can be explained by the gradual exchange of lecithin between red blood cells and plasma lipoprotein.

Biochemical studies on abnormal erythrocyte membranes. Protein abnormality of erythrocyte membrane in biliary obstruction

Biochemical studies on erythrocyte membranes from eleven obstructive jaundice patients (due to various disorders) have been undertaken, By scanning electron microscopic observation these erythrocytes were spur and target in appearance. The lipid composition showed a marked increase in both cholesterol and phosphatidylcholine. In addition to these changes, it was unexpectedly demonstrated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate that a specific membrane protein component 4.2 was reduced or absent in all cases tested. This membrane protein abnormality was identical with that of hereditary spherocytosis erythrocyte membranes. It is of particular interest to note that after surgical relief of biliary obstruction in a typical case of common duct cholelithiasis, the disc electrophoretic pattern of erythrocyte membranes became normal and both lipid composition and red cell morphology returned to normal.

Immunochemical studies on the human pathogen Sporothrix schenckii: effects of chemical and enzymatic modification of the antigenic compounds upon immediate and delayed reactions

The rhamnose-containing polysaccharide-peptide compound derived from the cells of the pathogenic fungus Sporothrix schenckii has been shown to contain 87.1% carbohydrate and 12.5% peptide and to give rise to both immediate- and delayed-type reactions in sensitized guinea pigs. The capacity to induce immediate-type reaction, passive cutaneous anaphylaxis, was completely lost by degradation of the carbohydrate moiety by periodate, whereas the ability to induce the delayed-type reactions of migration inhibition (in vitro) and the sporotrichin reaction (in vivo) were only slightly affected by periodate treatment. On the other hand, delayed "reactivities" to the compound were considerably reduced by treatment with papain, whereas the immediate-type reaction remained positive. These results lead to a conclusion that the rhamnose-containing polysaccharide of the polysaccharide-peptide antigenic compound plays an important role in the immediate-type reaction, whereas the peptide is largely responsible for the delayed-type reaction.