Linkage of the gene for an X-linked mental retardation disorder to a hypervariable (AGAT)n repeat motif within the human hypoxanthine phosphoribosyltransferase (HPRT) locus (Xq26).

We recently reported a new X-linked mental retardation (XLMR) disorder in a four-generation family of Dutch descent. Features included Dandy-Walker malformation, basal ganglia disease, and seizures. Twenty-six family members, including two living affected males and two obligate carriers, were available for study. No evidence of linkage was observed between the disease locus and RFLPs from several X-chromosome regions, including Xp21-p22 (13 markers), proximal Xq (four markers), and Xq28 (three markers). However, a new hypervariable short tandem repeat (STR) within the HPRT gene at Xq26 showed positive linkage to the disease locus, with a maximum lod score of 2.19 at a recombination fraction of 0. A second hypervariable marker in Xq26, the dinucleotide repeat XL90A3 (DXS425), showed a lod score of .84 at a recombination fraction of .11. Both the HPRT and DXS425 markers were typed in 40 CEPH families, and subsequent multipoint linkage analysis showed the following order: Xcen-DXS425-(HPRT,XLMR)-F9-qter. HPRT and these flanking markers are therefore useful for carrier detection and prenatal diagnosis in this family. This study illustrates that hypervariable STRs will be powerful tools for linkage analysis and genetic diagnosis, particularly when relatively small families are involved.     

Isethionate and taurine transport sites at brain cell membranes: Influx studies with brain slices

The influx of [¹⁴C]isethionate (ISA) into rat brain slices was studied with and without taurine. This influx was relatively rapid, but took place largely by a non-saturable, passive mechanism, which transferred much less ISA into the brain cells than taurine. Taurine inhibited the influx of ISA competitively (K _m=50 and 100 mol/l) at low ISA concentrations, and ISA that of taurine non-competitively (V=200 and 400–700 mol×min^–1×kg^–1 wet weight) at high taurine concentrations. It thus appears that ISA and taurine may have a small number of common transport sites at brain cell membranes, but these are apparently of little significance for the total transport of ISA.     

Methionine degradation inCandida utilis

Incubation of cell-free extracts ofC. utilis and its ethionine-resistant mutants with methionine, aspartate and alanine, and with various acceptor oxo-acids showed the presence of several transamination activities (Glu-Asp, Ala-Glu, Met-Glu, Met-Ala, Ala-Asp, but not Met-Asp). The lack of utilization of methionine by mec mutants appears to be due to a transport lesion.     

Reflexivity and countertransference in a psychiatric cultural consultation clinic

A Mexican-American woman who complained of persistent head pain and a bothersome voice was seen by a team consisting of a psychiatrist, social scientists, and spiritualist healers in a Cultural Consultation Clinic of a Psychiatric Consultation Liaison Service. This single case is analyzed to provide an understanding of the interpretive dimensions of psychiatric practice. It is argued that a hermeneutic analysis of clinical phenomena focuses attention on three distinct aspects of interpretation: on the interpretation by clinicians and clients of the discourse of the other in terms of their own clinical models; on the influence of deeply embedded personal meanings on this interpretive process; and on the role of the observer in clinical ethnography. It is argued that to sustain a hermeneutic analysis of psychiatric practice, an account of transference and countertransference in terms of interpretation theory will have to be developed.     

Use of permeabilized yeast cells as a system of enzyme immobilization. Its use for the preparation of mannose 6-phosphate

It was shown that hexokinase contained inside permeabilized yeast cells can be used successfully in the phosphorylation of mannose for the production of mannose 6-phosphate. We propose that enzymes entrapped within the semipermeable cell membrane be considered as an extension of the enzyme immobilization concept, since it shares many of its advantages and several of its properties with some unique characteristics.     

alpha1-Antitrypsin variants in different racial groups in Malaysia.

In a study of Malaysians of different racial groups, 1,510 sera (908 from Malays, 371 from Chinese and 231 from Indians) were identified for their protease inhibitor (Pi) types. The gene frequencies for the alleles PiM, PiS and PiX in Malays were, respectively, 0.979, 0.015, and 0.007. In Chinese, the frequencies were 0.981, 0.019 and 0.000, and in Indians they were 0.976, 0.24, and 0.000. It is interesting that the usually rare PiX type is found in appreciable frequency in the Malays. Two different types with unusual behavior and obscure origin were also found.     

A trophic diversity index for presence-absence food data

Summary An index to assess trophic diversity from presence-absence food data is proposed. The index is computed according to the expression , where the 's are the frequencies of occurrence of the various prey categories. The upper and lower limits of D are derived. A test of the reliability of D was carried out by comparing D and H (Shannon's information function) values obtained from a set of twenty-three food analyses from vertebrate animals. Results show that, although a significant correlation exists between D and H, only a small fraction of H-variation is explained by D-variation. D contains two kinds of information, one referred to species richness and another relative to the degree of between-samples heterogeneity. The former is shared in common with H and this presumably explains the fairly weak correlation found between both measures.     

Novel Tools to Analyze the Function of Salmonella Effectors Show That SvpB Ectopic Expression Induces Cell Cycle Arrest in Tumor Cells

In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ∆purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors.