Survival experience among elderly end-stage renal disease patients. A controlled comparison of transplantation and dialysis

Renal transplantation is a relatively recent treatment option among the elderly with end-stage renal disease (ESRD). Since little is known regarding the clinical benefits of transplantation relative to dialysis in this age group, this study compares transplantation and dialysis among the elderly with respect to patient survival. Data utilized in this investigation were obtained from the Canadian Organ Replacement Register (CORR). The study population consisted of the 6400 patients aged 60 and over at registration, diagnosed between 1987 and 1993, for whom data on comorbid conditions were available. Survival probability, death rates, age-standardized mortality ratios (SMRs) and Cox regression analysis were employed to evaluate the survival experience among the transplant and dialysis groups. Transplant recipients were matched (by age, underlying diagnosis leading to ESRD, and number of comorbid conditions) to 2 randomly selected patients who did not undergo transplantation. Using Cox regression, the time-dependent hazard ratio for transplantation versus dialysis patients was estimated at 0.47 (P < 0.0001), indicating that even after adjusting for other known prognostic factors, elderly patients who received a transplant experienced significantly greater survival probability than those who remained on dialysis. When transplant patients were matched to randomly selected dialysis patients with the constraint that the corresponding dialysis patient have at least as much follow-up time as the transplant patient had waiting time, five-year survival rates were 81% and 51% for the transplant and dialysis groups, respectively (P < 0.0001). These results support the potential advantage of transplantation among the elderly, and may have important implications for renal care in this age group.

Short-chain dehydrogenases/reductases (SDR)

Short-chain dehydrogenases/reductases (SDR) constitute a large protein family. Presently, at least 57 characterized, highly different enzymes belong to this family and typically exhibit residue identities only at the 15-30% level, indicating early duplicatory origins and extensive divergence. In addition, another family of 22 enzymes with extended protein chains exhibits part-chain SDR relationships and represents enzymes of no less than three EC classes. Furthermore, subforms and species variants are known of both families. In the combined SDR superfamily, only one residue is strictly conserved and ascribed a crucial enzymatic function (Tyr 151 in the numbering system of human NAD(+)-linked prostaglandin dehydrogenase). Such a function for this Tyr residue in SDR enzymes in general is supported also by chemical modifications, site-directed mutagenesis, and an active site position in those tertiary structures that have been characterized. A lysine residue four residues downstream is also largely conserved. A model for catalysis is available on the basis of these two residues. Binding of the coenzyme, NAD(H) or NADP(H), is in the N-terminal part of the molecules, where a common GlyXXXGlyXGly pattern occurs. Two SDR enzymes established by X-ray crystallography show a one-domain subunit with seven to eight beta-strands. Conformational patterns are highly similar, except for variations in the C-terminal parts. Additional structures occur in the family with extended chains. Some of the SDR molecules are known under more than one name, and one of the enzymes has been shown to be susceptible to native, chemical modification, producing reduced Schiff base adducts with pyruvate and other metabolic keto derivatives. Most SDR enzymes are dimers and tetramers. In those analyzed, the area of major subunit contacts involves two long alpha-helices (alpha E, alpha F) in similar and apparently strong subunit interactions. Future possibilities include verification of the proposed reaction mechanism and tracing of additional relationships, perhaps also with other protein families. Short-chain dehydrogenases illustrate the value of comparisons and diversified research in generating unexpected discoveries.

Enzymes: chemistry and biochemistry

Basic principles underlying enzyme action are considered. Catalytic antibodies (abzymes), catalytic RNA (ribozymes), and non-biological counterparts of enzyme-catalyzed reactions are mentioned. Enzyme evolution is considered in terms of divergence, convergence, and lateral gene transfer.

Renal replacement therapy in Canada: a report from the Canadian Organ Replacement Register

We report here the demography and results of renal replacement therapy in Canada from 1981 to 1992. The new case rate for patients entering renal replacement therapy programs in Canada has increased dramatically over the last 12 years, from 49.9 per million to 98.4 per million of the population. The largest increases have been among the elderly, from 146.2 per million in 1981 to 381.9 per million in 1992 for those aged 65 to 74 years. There has been an even more dramatic increase for those over 75 years, from 83.6 per million in 1981 to 261.6 per million in 1992. There has been a similar increase in the prevalence rate, with an increase from 229.1 per million in 1981 to 518.5 per million in 1992. The hemodialysis rate for 1992 was 172.2 per million and that for peritoneal dialysis was 103.1 per million of the population. The renal transplantation rate also increased from 20 per million in 1981 to 34.8 per million in 1988, but unfortunately has decreased to 27.5 per million in 1992. Diabetes is now the most common primary renal diagnosis, having increased from 15% in 1981 to 24% in 1992. The 5-year survival rate of all patients on renal replacement therapy was 55%. For nondiabetic patients, the 5-year survival rate ranged from 85% for the those aged 15 to 44 years to 20% for those over 65 years. Among diabetic patients, the 5-year survival rate declined from 58% for the 15 to 44 year age group to 10% for those over 65 years.

Field studies on populations of Aedes albopictus and Toxorhynchites species in bamboo pots in Malaysia

Between April 1987 and March 1988, populations of immature Aedes albopictus and Toxorhynchites spp. in bamboo pots were sampled weekly. Populations of Ae. albopictus and rainfall varied from month to month. During the heavy rainfall months of September and October 1987, larval counts of Ae. albopictus were high, between 30.8 and 49.2 larvae per week compared to 16 larvae per week during the low rainfall month of January 1988. A higher population of Toxorhynchites spp. was associated with a low population of the vector.

Bacterial morphine dehydrogenase further defines a distinct superfamily of oxidoreductases with diverse functional activities

Pseudomonas putida morphine dehydrogenase is shown to be closely homologous to 18 proteins, defining a superfamily within which morphine dehydrogenase particularly resembles two bacterial, 2,5-dioxo-D-gluconic acid reductases, and two eukaryotic proteins of unknown functions. Relationships within the superfamily are extensive and complex. Residue identities between protein pairs range from 29-90%. Three subgroups are proposed. Nevertheless, on the basis of residue conservations/exchanges it is suggested that the nicotinamide coenzyme binding and substrate reduction occur in all the enzymes by broadly analogous mechanisms, among which some probable differences are identified.

Loss of anionic sites on the glomerular basement membrane in transplant glomerulopathy

We studied anionic sites on the glomerular basement membrane in patients with chronic renal transplant rejection having clinical and histological features of transplant glomerulopathy. All patients had significant proteinuria (greater than 1 g/24 h as well as light- and electron-microscopic features very like focal segmental glomerulosclerosis, though no patient had that disease in the native kidney. A significant reduction in the density and absolute number of anionic sites was observed compared with controls and with patients having stable graft function. The findings suggest that the loss of anionic sites may play an important part in the pathogenesis of transplant glomerulopathy.

Host tissue reaction to Gnathostoma malaysiae (Nematoda: Gnathostomidae) in Rattus surifer Miller

The occurrence of adult Gnathostoma malaysiae in Rattus surifer and R. tiomanicus in Malaysia has been reported but there are no known reports on the host tissue reactions. This paper reports on the gross pathology caused by G. malaysiae in a red spiny forest rat, R. surifer and the tissue reactions caused. A tumor-like growth was located on the mid-stomach wall in a female rat captured in Gunung Bachock, Kelantan, Malaysia. This growth consisted of four tunnel-like structures containing sanguinopurulent fluid and leukocytes and this structure led into a central canal. The tissue surrounding the tumor was greatly inflamed and there was localized gastritis. The tunnel-like structure was surrounded by dense fibrotic tissue. The stomach wall was devoid of superficial epithelium and smooth muscle but mucinous glands were present. The midregion of the fibrotic scar contained eggs of G. malaysiae which had evoked a strong tissue reaction and were surrounded by pus. Blood vessels were empty, dilated and had undergone vasculitis and thrombosis.

Glucose-6-phosphate dehydrogenase. Structure-function relationships and the Pichia jadinii enzyme structure

The primary structure of glucose-6-phosphate dehydrogenase from the yeast Pichia jadinii (formerly Candida utilis) has been determined. It consists of a 495-residue, N-terminally acetylated protein chain. The structure shows extensive differences from those of the corresponding mammalian, fruit fly, and bacterial enzymes (52-68% residue non-identities), but also from that of another yeast, Saccharomyces cerevisiae (38%). A eubacterial type and a yeast type of glucose-6-phosphate dehydrogenase are discerned, in addition to the known mammalian type. They are distinguished from each other, from the mammalian type, and the insect enzyme, on the basis of both specific residues and pattern differences. The distribution of residues conserved in all forms locates short segments in which identities are closely grouped. Approximately 50% of these segments correspond to predicted turns and appear to mark the principal folds characteristic of the enzyme's tertiary structure. A region in the N-terminal part of the protein chain has characteristics suggestive of a coenzyme-binding site, while, in the middle third, another functionally important segment may be related to glucose-6-phosphate binding and catalysis.

Prevalence of Enterobius vermicularis amongst adults living in hostels by six successive day examination

The prevalence of Enterobius vermicularis in four groups of adults, all trainee public health inspectors or public health nurses, aged 18-35 years and all living in hostels on campus was studied. The modified scotch tape technique was used and the subjects were taught to do the examination on themselves to detect the presence of eggs over a period of 6 successive mornings. Each was given an elaborately illustrated diagram on how and when to take the samples and given demonstration in groups. The samples were examined by trained people. Most of the subjects took samples on 6 consecutive days. Of the 119 subjects who returned samples, the overall prevalence of E. vermicularis was 9.2% and this was thought to be high for this particular age group. This was due to the higher prevalence (19.4%) in one group, whereas in the others the range was 3.5-8.0%. Based on the samples returned on the first day none of the subjects were detected as having the infection. After examination on 3 successive days (109 subjects) 10.1% were found to be infected (chi 2 = 10.704; d. f. = 1) and after examination on 6 successive days (72 subjects) 13.9% were found to be infected (chi 2 = 3.026; d. f. = 1). There was no significance between examination over 3 successive days and 6 consecutive days (chi 2 = 0.296; d. f. = 1). There was no difference in the prevalence between males and females.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of glucose-primed intravenous glucose tolerance and correction of acute insulin decrement by glipizide in type II diabetes

Improved glucose disposal after repeated intravenous (IV) glucose loads, known as the Staub effect, is absent in both type I and type II diabetes. Acute decrements of insulin secretion (AID) are observed following the early phase of insulin release on IV glucose stimulation in non-insulin-dependent diabetes mellitus (NIDDM). The AID cannot be corrected by acute infusions of glyburide or glipizide, or phentolamine, or by glycemic control after 2 weeks of intensive insulin treatments. Fifteen male subjects had 3 hourly successive IV glucose tolerance tests before and after 6 months of glipizide, at a final maintenance dose of 30 +/- 3 mg/d. Before treatment, AID, defined as the difference of the lowest of post IV glucose 7- or 10-minute samples from the preceding baseline insulin levels, was detected in the three loads: -6.4 +/- 1.9 microU/mL in the first, and then more consistently in the second and third loads, -11 +/- 2 microU/mL, and -17 +/- 9 microU/mL, respectively. There was a stepwise increase in insulin sums after each load. After glipizide therapy, the AIDS following all three IV glucose loads were no longer demonstrable; both insulin values, as well as insulin sums, were significantly elevated after all three glucose loads. While in the untreated state, the Staub effect was absent: serum glucose disappearances (K), corrected for glycosuria, were K1 = 0.52 +/- 0.02, K2 = 0.50 +/- 0.04, and K3 = 0.52 +/- 0.03.(ABSTRACT TRUNCATED AT 250 WORDS)

Functionally important regions of glucose-6-phosphate dehydrogenase defined by the Saccharomyces cerevisiae enzyme and its differences from the mammalian and insect forms

The primary structure of Saccharomyces cerevisiae glucose-6-phosphate dehydrogenase has been determined. It consists of 503 amino acid residues, with an acetyl-blocked N-terminus. The structure shows equally extensive differences from the corresponding mammalian and fruit fly enzymes (52% residues non-identical). Residues conserved in all the forms constitute about 40% of the structures and include two histidines. One of these (His200 in the numbering of the rat enzyme) occurs in a 10-residue conserved segment, including the reactive Lys204, probably related to substrate binding. Two segments with conserved Gly-Xaa-Xaa-Gly-Xaa-Xaa-Gly/Ala pattern constitute possibilities for the coenzyme-binding site. One is N-terminally located (positions 37-43) with two conserved arginine residues nearby (positions 56 and 71), of interest for phosphate binding. The other (positions 241-247) is in a middle region, with many residue identities, containing the conserved residues Arg256 and His264.

Different segment similarities in long-chain dehydrogenases

Long-chain dehydrogenases were scrutinized for common patterns. Overall molecular similarities are not discerned, in contrast to the situation for several short-chain and medium-chain dehydrogenases, but coenzyme-binding segments are discernible. Species variants of glucose-6-phosphate dehydrogenase reveal about 20% strictly conserved residues, grouped into three segments and supporting assignments of sites for coenzyme-binding and catalysis. Glycine is overrepresented among the residues conserved, typical of distantly related proteins. Two of the enzymes within the pentose phosphate pathway reveal a distant similarity of interest for further evaluation, between a C-terminal 178-residue segment of glucose-6-phosphate dehydrogenase and the N-terminal part of 6-phosphogluconate dehydrogenase.

Eukaryotic glucose-6-phosphate dehydrogenases: structural screening of related proteins

Rapid assessment of structural relationships between yeast glucose-6-phosphate dehydrogenases and other eukaryotic types of this enzyme is described. Separation and size estimation of large fragments by sodium dodecylsulfate/polyacrylamide gel electrophoresis, electroblotting onto disks, and sequencer analysis provide data that permit alignment of the segments thus characterized with the related proteins, and utilize existing structural knowledge to assess new enzyme structures. Affinity labeling allows further correlations. The results establish the overall structural arrangements of the new proteins, including the location of the active-site lysine residue, even though the yeast enzyme structures are found to differ markedly from the few previously characterized glucose-6-phosphate dehydrogenases.

Evaluation of Bactimos wettable powder, granules and briquets against mosquito larvae in Malaysia

There was high mortality in late larval instars of Aedes albopictus (Skuse) from laboratory and field populations in the 24 h after application of three Bactimos formulations of Bacillus thuringiensis H-14. Mortalities were higher and residual effects longer in field populations than in laboratory ones. Briquets were the most effective formulation (mortality 96-100% after five weeks; 76-92% after eight weeks). Culex quinquefasciatus Say larvae were tested only against the briquet formulation. In the laboratory, 100% mortality of late instars persisted for six weeks and dropped to 48-88% after eight weeks. In the field, late instars were reduced by 62-87% after 24 h and 69-72% after one week compared to increases in an untreated population of 160% and 176% respectively.

Glucose-6-phosphate dehydrogenase. Characteristics revealed by the rat liver enzyme structure

The primary structure of glucose-6-phosphate dehydrogenase from rat liver has been determined, showing the mature polypeptide to consist of 513 amino acid residues, with an acyl-blocked N-terminus. This structure is homologous to those of both other eutherian and marsupial mammals (human and opossum), thus characterizing a mammalian type enzyme to which the human form, notwithstanding its large number of genetic variants, conforms. The mammalian type differs from the fruit fly enzyme by about 50%. Known mutant forms exhibit further differences, widely distributed along the polypeptide chain. Structural patterns show glucose-6-phosphate dehydrogenases to consist of a few variable regions intermixed with relatively constant segments.

Zinc environment in sheep liver sorbitol dehydrogenase

The extended X-ray absorption fine structure (EXAFS) associated with the zinc K-absorption edge has been recorded for sorbitol dehydrogenase. It is interpreted in terms of one cysteine sulfur among the ligands to the active site zinc atom. Simulations of the EXAFS based on the presence of two such sulfurs are less satisfactory, and comparison with the EXAFS of such systems points to the presence of only one sulfur ligand in sorbitol dehydrogenase. These results provide evidence that sorbitol dehydrogenase does not have the characteristic one water, one His, two Cys arrangement of ligands to the active site zinc found in the homologous alcohol dehydrogenases and are consistent with the one water, one His, one Cys, one Glu ligand arrangement of the proposed model of sorbitol dehydrogenase [Eklund, H., Horjales, E., Jörnvall, H., Brändén, C.-I., & Jeffery J. (1985) Biochemistry 24, 8005-8012]. Evidence for the correctness of the model is also evidence for validity of predictive techniques used in constructing the model, i.e., computer graphics fitting of the amino acid sequence to the crystallographically derived structure of a different but homologous protein.

Glucose-6-phosphate dehydrogenase. Characterization of a reactive lysine residue in the Pichia jadinii enzyme reveals a limited structural variation in a functionally significant segment

Glucose-6-phosphate dehydrogenase from the yeast Pichia jadinii has a reactive lysine residue in a segment of amino acid sequence Ile-Asp-His-Tyr-Leu-Gly-Lys*-Glu-Met-Val-Lys. This structure differs from that of other characterized glucose-6-phosphate dehydrogenases, but outside yeasts the segment is invariant in known mammalian, insect and bacterial forms. Thus, limited structural variation is now defined within yeasts for a part of the protein otherwise strictly conserved, and for which stringent structural requirements probably relate to enzymic mechanisms.