Aspartate 155 of human transketolase is essential for thiamine diphosphate-magnesium binding, and cofactor binding is required for dimer formation.

Active human transketolase is a homodimeric enzyme possessing two active sites, each with a non-covalently bound thiamine diphosphate and magnesium. Both subunits contribute residues at each site which are involved in cofactor binding and in catalysis. His-tagged transketolase, produced in E.

A transketolase assembly defect in a Wernicke-Korsakoff syndrome patient.

Thiamine deficiency, a frequent complication of alcoholism, contributes significantly to the development of damage in various organ systems, including the brain. The molecular mechanisms that underlie the differential vulnerabilities to thiamine deficiency of tissue and cell types and among individuals are not understood. Investigations into these mechanisms have examined potential variations in thiamine utilizing enzymes.

Age-related trends (1986-1993) in the use of thrombolytic agents in patients with acute myocardial infarction. The Worcester Heart Attack Study.

Objective: To examine age-related differences and temporal trends in the use of thrombolytic therapy in a community-wide study of patients hospitalized with acute myocardial infarction (AMI) between 1986 and 1993.

Methods: All hospitals in the Worcester, Mass, metropolitan area (1990 census population, 4370000) were included. A total of 3824 patients with validated AMI categorized according to age comprised the study sample: younger than 55 years (n = 577), 55 to 64 years (n = 758), 65 to 74 years (n = 1143), and 75 years or older (n = 1346).

Conserved residues are functionally distinct within transketolases of different species.

Most of the amino acid residues which interact with thiamine pyrophosphate are highly conserved among enzymes which use this cofactor. The possible roles of several such residues in cofactor binding, catalysis, and/or substrate binding were examined for human transketolase. Mutations in H110 resulted in dramatic reductions to 2% or less of the normal activity.

Wild-type strains of Dictyostelium discoideum can be transformed using a novel selection cassette driven by the promoter of the ribosomal V18 gene.

Almost all methods for transformation of the social ameba Dictyostelium discoideum rely on axenic growth, that is, growth in a synthetic medium, for at least part of the procedure. Axenic growth requires several mutations. Here we describe a procedure that can be used to transform wild-type strains which are able to grow only on the natural food source, bacteria.

Thiamine pyrophosphate-requiring enzymes are altered during pyrithiamine-induced thiamine deficiency in cultured human lymphoblasts.

The most common of the severe complications of thiamine deficiency are beriberi and Wernicke-Korsakoff syndrome. To help clarify the biochemical basis for these disorders, a cell culture system has been established in which pyrithiamine, a potent thiamine transport inhibitor, was used to mimic different degrees of thiamine deficiency within human lymphoblasts. Activities of both transketolase and alpha-ketoglutarate dehydrogenase (alpha-KGDH) decreased at the same rate and to roughly the same levels in response to thiamine deficiency within a given cell line.

Transcultural perioperative nursing in Berlin.

Political events and military base closures in the early 1990s caused the US Army Hospital, Berlin, to extend care to include British military forces and to contract the services of civilian German surgeons and nurses. This article describes transcultural perioperative nursing in Berlin from 1991 to 1994. It also compares the differences between American, British, and German military and civilian expectations of OR nurses, anesthesia care providers, and surgeons and explores nursing education, licensing, practice issues, and socialized medicine in a transcultural environment.

A reliable and sensitive method for fluorescent photoconversion.

The objective of this study was to develop a reliable and sensitive method of diaminobenzidine (DAB) photoconversion through systematic variation of the objectives and the method of DAB enhancement employed. Results showed that reliable photoconversion of DiI-labeled macaque monkey cortical cells and processes can be obtained consistently by using fresh filtered DAB solutions, clean slides, and a bright fluorescent light source. Using a 20x objective and enhancing the DAB reaction product with Giemsa stain provided the most sensitivity and best resolution in the photoconverted area.

Molecular genetics of transketolase in the pathogenesis of the Wernicke-Korsakoff syndrome.

Thiamine deficiency, a frequent complication of alcoholism, plays an important role in the pathogenesis of the Wernicke-Korsakoff syndrome [WKS]. Previous work by a number of investigators has implicated the thiamine-utilizing enzyme transketolase [Tk] as being involved mechanistically in the genetic predisposition to WKS. In particular, Tk derived from fibroblasts has been found to have an increased Km app for its cofactor thiamine pyrophosphate [TPP] and/or exist in different isoelectric forms in alcoholic patients with WKS as compared with unaffected individuals.

The thiamine-dependent hysteretic behavior of human transketolase: implications for thiamine deficiency.

We have investigated the hysteretic properties of human transketolase with emphasis on its dependency on thiamine pyrophosphate concentration. As demonstrated previously, the reaction progress curves revealed a slow transition from an initial low velocity to a faster final steady-state velocity, characterized by the rate constant tau-1. The rate of the transition was dependent on the concentration of the thiamine pyrophosphate cofactor, with progressively longer transition times found as the concentration of thiamine pyrophosphate was decreased.

Thiamine utilization in the pathogenesis of alcohol-induced brain damage.

There is increasing evidence for the role of thiamine deficiency in ethanol neurotoxicity and in development of alcoholic organic brain disorders other than Wernicke-Korsakoff syndrome [WKS] and cerebellar degeneration. Investigations in humans and in animal models have implicated a reduction in the activities of thiamine-utilizing enzymes as the metabolic basis of tissue injury due to thiamine deficiency. We have investigated the interactions of the thiamine-utilizing enzyme transketolase [Tk], derived from human fibroblasts, lymphoblasts, and various brain regions, with its cofactor, thiamine pyrophosphate [TPP], in an attempt to elucidate the molecular basis of selective brain damage in alcoholism-associated thiamine deficiency.

Redundant regulatory elements account for the developmental control of a ribosomal protein gene of Dictyostelium discoideum.

In Dictyostelium discoideum, ribosomal protein genes along with other growth specific genes appear to be coordinately regulated, primarily in response to differences in the translational capacity of developing versus growing cells. In particular, expression of the members of this large class of genes is rapidly and dramatically deactivated when the developmental program is initiated and growth and division cease. In order to understand the mechanisms behind the deactivation event and how it is coupled to the transition from growth to development, we have analyzed the promoter of the V18 gene, a ribosomal protein gene characteristic of this class of growth specific genes.

Pretransport Pediatric Risk of Mortality (PRISM) score underestimates the requirement for intensive care or major interventions during interhospital transport.

Objective: To test the hypothesis that a pretransport Pediatric Risk of Mortality (PRISM) score underestimates the requirement for both intensive care and interventions during pediatric interhospital transport.

Design: Prospective, descriptive study.

Setting: All children were treated in a regional hospital and then transported to a pediatric tertiary care center by a pediatric critical care specialty team.

Nutrient-responsive promoter elements of the V4 gene of Dictyostelium discoideum.

Expression of the V4 gene of Dictyostelium discoideum is required for the transition from growth to development in response to an altered nutrient environment. In addition, the expression itself is sensitive to the types and amounts of nutrients supporting growth. We describe the structure of the two copies of the V4 gene and the relationship between these genes and the two V4 mRNA species produced during growth.

Cloning of human transketolase cDNAs and comparison of the nucleotide sequence of the coding region in Wernicke-Korsakoff and non-Wernicke-Korsakoff individuals.

Variants of the enzyme transketolase which possess reduced affinity for its cofactor thiamine pyrophosphate (high apparent Km) have been described in chronic alcoholic patients with Wernicke-Korsakoff syndrome. Since the syndrome has been shown to be directly related to thiamine deficiency, it has been hypothesized that such transketolase variants may represent a genetic predisposition to the development of this syndrome. To test this hypothesis, human transketolase cDNA clones were isolated, and their nucleotide and predicted amino acid sequence were determined.

V4, a gene required for the transition from growth to development in Dictyostelium discoideum.

The V4 gene of Dictyostelium discoideum is regulated in a nutrient-dependent manner and is deactivated immediately upon the onset of development. V4 is expressed only during growth, but its expression is not required for growth. We propose that the V4 gene product plays a role in the transition from growth to development.

Points of View.

'Nurses required for World Student Games', the advertisement read.