Complete nucleotide sequence of the murine H-2Kk gene. Comparison of three H-2K locus alleles.

We have determined the DNA sequence of the H-2Kk gene of the mouse major histocompatibility complex (MHC). Comparison on the nucleotide and protein level of three H-2K alleles (Kk, Kb and Kd) reveals a high degree of homology, in particular between the Kb and Kk alleles. Differences between the two latter antigens are almost exclusively confined to the alpha 1 and alpha 2 domains. At nine positions in the extracellular part of the molecules we have found allele-specific amino acids. Interestingly, 78% of these residues are either polar or carry hydroxyl-groups. This makes it likely that they are exposed on the surface of the molecules and might then be part of antigenic determinants. We have also identified potentially allele-specific nucleotide sequences of the K genes which might be used as specific DNA probes.     

Carbohydrate composition of purified serum glycoproteins in Mucolipidosis II and Mucolipidosis III

Summary Mucolipidosis II (I-cell disease) and Mucolipidosis III (ML III) are inherited disorders in which the molecular defect may involve an abnormality in a common post-translational modification step (possibly glycosylation) shared by lysosomal hydrolases. We tested whether such an alteration might be a generalized defect in glycoprotein biosynthesis and, thus, be reflected in an abnormal carbohydrate composition of non-lysosomal glycoproteins. The apoprotein of low density lipoprotein (apo-LDL) and immunoglobulin G (IgG) were purified to apparent homogeneity. Gas liquid chromatographic (glc) analysis of the carbohydrate content of these glycoproteins from ML II, ML III and normal sera revealed no differences in the relative ratios and total amounts of mannose, galactose, N-acetylglucosamine and sialic acid. These results suggest that if the postulated post-translational defect in these disorders involves changes in carbohydrate composition, it is not a general defect in glycosylation and may be specific for lysosomal hydrolases.     

13C-NMR of double and triple bond carbon atoms of unsaturated fatty acid methyl esters

The carbon magnetic resonance spectra of many fatty acid methyl esters with cis and trans double bonds and triple bonds at various positions and in many different combinations have been investigated.The influence of the ester group on double and triple bonds in the fatty acid chain depends strongly on the positions of these bonds. For a given position the influence is constant, even if one or more other double or triple bonds are present.Together with the evaluated chemical shift parameters for the effects of double and triple bonds on each other, complete assignments are possible and spectra of various types of unsaturated esters can be predicted with high accuracy (±0.1 ppm).     

Tetrahydrofolate-dependent biosynthesis of ribothymidine in transfer ribonucleic acids of Gram-positive bacteria.

Trimethoprim, an inhibitor that prevents tetrahydrofolate-dependent transmethylation reactions inbacteria, was used in a comparative study to discriminate between two possible biosynthetic pathways, either the S-adenosylmethionine or the tetrahydrofolate-dependent formation of ribothymidine (rT) in transfer ribonucleic acids (tRNA's) of several strains of gram-positive and gram-negative microorganisms. rT-deficient tRNA's accumulate in trimethoprim-treated gram-positive Streptococcus faecium, Staphylococcus aureus, Corynebacterium bovis, Arthrobacter albidus, and all examined Bacillaceae, except Bacillus stearothermophilus. The rT-deficient rT-deficient tRNA's accept the methyl moiety from S-adenosylmethionine in vitro, with extracts from Escherichia coli (wild type) as a source of methylating enzymes; 90% of the incorporated methyl groups are present in rT. Trimethoprim does not inhibit the biosynthesis of rT in tRNA of gram-negative Enterobacteriaceae, Rhizobium lupini, and Pseudomonadaceae, suggesting that the rT-specific tRNA methyltransferases of these gram-negative strains use S-adenosylmethionine as coenzyme.     

Somatostatin and insulin release from isolated rat pancreatic islets in response to D-glucose, l-leucine, alpha-ketoisocaproic acid or D-glyceraldehyde: evidence for a regulatory role of adenosine-3' ,5'-cyclic monophosphate.

Somatostatin and insulin release from isolated rat pancreatic islets was stimulated by glucose, leucine or α-ketoisocaproic acid. D-glyceraldehyde stimulated insulin release but diminished the secretion of somatostatin. Glucagon and theophylline amplified the glucose-induced somatostatin release.A regulatory role of the D-cell's adenylate cyclase/phosphodiesterase system for the release of somatostatin is suggested. Furthermore, stimulation as well as inhibition of somatostatin release might be of significance for the secretory function of the B-cell.     

Kidney Stones

The prevalence of kidney stones has steadily risen during this century; passage of a calculus and a positive family history increase the probability of recurrence. Findings from recent studies on the cause of renal calculi have stressed crystallization and crystal aggregation of stone minerals from supersaturated urine, rather than excessive organic matrix. Absence of normal urine inhibitors of calcium salts is also stressed. Formation of calcium oxalate stones is the major problem. Therapy with decreased calcium and oxalate intake, thiazides, phosphate salts and allopurinol in various combinations has substantially decreased the prevalence of recurrent stones. The rationale for the use of allopurinol is that uric acid salts enhance the tendency for calcium oxalate to crystallize from supersaturated urine. The hypercalciuria seen in 30 percent to 40 percent of patients with oxalate stones is usually caused by intestinal hyperabsorption of calcium. Although patients with uric acid calculi constitute only a small fraction of those in whom stones form, they represent a group in whom good medical therapy, based on sound physiologic principles, has proved extremely successful. Renal tubular syndromes lead to nephrocalcinosis and lithiasis through hypercalciuria, alkaline urine and hypocitraturia, the latter an inhibitor of calcium salt precipitation. Recent advances in surgical techniques are discussed, including the rationale for removing staghorn calculi. The ileal ureter and coagulum pyelolithotomy deserve special emphasis.