Glutathione S-transferase GSTM1, GSTT1 and p53 codon 72 polymorphisms in human tumor cells

The genes of the glutathione S-transferase (GST) family encode enzymes that appear to be critical in cellular protection against the cytotoxic effects, whereas p53 is a tumor suppressor gene. Despite a large number of studies on germline polymorphisms of GSTM1, GSTT1 and p53 genes, there have been very few reports on genotyping of these genes in human malignant tumor cells. In this study, we investigated GSTM1, GSTT1 and p53 codon 72 polymorphisms in a variety of human tumor cell lines originating from different organs to clarify tissue-specific polymorphic frequency of these genes in human solid tumors. The GSTM1 and GSTT1 genetic polymorphisms were evaluated using multiplex PCR techniques and PCR-RFLP analysis was conducted to identify p53 codon 72 genotypes. Gene expression of GSTM1 or GSTT1 was detected by RT-PCR in the cells with respective present genotype for each. Polymorphisms of p53 codon 72 detected by PCR-RFLP were also confirmed using SSCP and sequence analyses. GSTM1 and GSTT1 genotypes were various in 104 cell lines examined. Null GSTM1 genotype was dominant in small cell lung, kidney and ovarian carcinoma cells, whereas null GSTT1 genotype was dominant in cervical and endometrial carcinoma cells. GSTM1 and GSTT1 genotypes in ovarian carcinoma cells were quite similar to those in small cell lung carcinoma cells. Polymorphic frequency of p53 codon 72 was also various among the cells, however, the Pro allele was found in only 1 of 6 kidney, 14 cervical and 4 endometrial carcinoma cell lines. There was a significant difference in GSTM1 and p53 genotypes between 34 small cell and 24 non small cell lung carcinoma cells (P < 0.01). Combined study on the distribution of GSTM1, GSTT1 and p53 genotypes revealed that null GSTM1 genotype was associated with the Arg allele of p53 codon 72 in 58 lung carcinoma cells and null GSTT1 genotype was associated with the Pro/Pro homozygote in 104 tumor cell lines examined. This is the first study examining GSTM1, GSTT1 and p53 codon 72 polymorphisms in a variety of human solid tumor cells and suggesting that polymorphic frequency of these genes may be tissue- and organ-specific. The molecular interaction between GST gene defects and p53 codon 72 genotype in the development of human malignant tumors should be further investigated.     

Reversal of denervation-induced insulin resistance by SHIP2 protein synthesis blockade

Short-term muscle denervation is a reproducible model of tissue-specific insulin resistance. To investigate the molecular basis of insulin resistance in denervated muscle, the downstream signaling molecules of the insulin-signaling pathway were examined in intact and denervated soleus muscle of rats. Short-term denervation induced a significant fall in glucose clearance rates (62% of control, P < 0.05) as detected by euglycemic hyperinsulinemic clamp and was associated with a significant decrease in insulin-stimulated tyrosine phosphorylation of the insulin receptor (IR; 73% of control, P < 0.05), IR substrate 1 (IRS1; 69% of control, P < 0.05), and IRS2 (82% of control, P < 0.05) and serine phosphorylation of Akt (39% of control, P < 0.05). Moreover, denervation reduced insulin-induced association between IRS1/IRS2 and p85/phosphatidylinositol (PI) 3-kinase. Nevertheless, denervation caused an increase in PI 3-kinase activity associated with IRS1 (275%, P < 0.05) and IRS2 (180%, P < 0.05), but the contents of phosphorylated PI detected by HPLC were significantly reduced in lipid fractions. In the face of the apparent discrepancy, we evaluated the expression and activity of the 5-inositol, lipid phosphatase SH2 domain-containing inositol phosphatase (SHIP2), and the serine phosphorylation of p85/PI 3-kinase. No major differences in SHIP2 expression were detected between intact and denervated muscle. However, serine phosphorylation of p85/PI 3-kinase was reduced in denervated muscle, whereas the blockade of SHIP2 expression by antisense oligonucleotide treatment led to partial restoration of phosphorylated PI contents and to improved glucose uptake. Thus modulation of the functional status of SHIP2 may be a major mechanism of insulin resistance induced by denervation.     

Focus group interviews examining attitudes toward medical research among the Japanese: a qualitative study

Objectives: the purpose of ths study is to explore laypersons' attitudes towards and experiences of medical research, and to compare them with those of physicians in Japan. Designs and Participants: fourteen Japanese adults from the general public and seven physicians participated in one of three focus interviews. Setting: Osaka, Japan. Results: trust and distrust in the physician by whom the participants were invited to participate in research played a considerable role in their decisions about participation. That the participants felt an obligation to participate was also expressed. The lay participants perceived medical research as something entirely outside of their world. A greater willingness to volunteer for research was expressed if there were direct benefits to themselves or their families. Research methods such as use of placebos, double blinds, and randomisations seemed to cause negative attitudes to medical research. All physicians were convinced of the need for medical research, including double-blinded randomised control trials, and its significant role in medical progress. Most physicians thought that the greater awareness of the need for medical research in the community and a better understanding of the psychology of potential research participants were necessary and urgent. Conclusions: there is a good possibility that the lay public and medical professionals have sharply different beliefs about and attitudes towards every aspect of medical research. Building up a better and equal patient-doctor relationship based on trust is a key issue in medical research, and it is mandatory to fill the gap in perception regarding medical research between them through fully informed debates.     

Crotacetin, a novel snake venom C-type lectin homolog of convulxin, exhibits an unpredictable antimicrobial activity

Snake venom (sv) C-type lectins encompass a group of hemorrhagic toxins that are capable of interfering with blood stasis. A very well-studied svC-type lectin is the heterodimeric toxin, convulxin (CVX), from the venom of South American rattlesnake Crotalus durissus terrificus. CVX is able to activate platelets and induce their aggregation by acting via p62/GPVI collagen receptor. By using polymerase chain reaction homology screening, we have cloned several cDNA precursors of CVX subunit homologs. One of them, named crotacetin (CTC) β-subunit, predicts a polypeptide with a topology very similar to the tridimensional conformations of other subunits of CVX-like snake toxins, as determined by computational analysis. Using gel permeation and reverse-phase high-performance liquid chromatography, CTC was purified from C. durissus venoms. CTC can be isolated from the venom of several C. durissus subspecies, but its quantitative predominance is in the venom of C. durissus cascavella. Functional analysis indicates that CTC induces platelet aggregation, and, importantly, exhibits an antimicrobial activity against Gram-positive and-negative bacteria, comparable with CVX.     

Liver autophagy contributes to the maintenance of blood glucose and amino acid levels

Both anabolism and catabolism of the amino acids released by starvation-induced autophagy are essential for cell survival, but their actual metabolic contributions in adult animals are poorly understood. Herein, we report that, in mice, liver autophagy makes a significant contribution to the maintenance of blood glucose by converting amino acids to glucose via gluconeogenesis. Under a synchronous fasting-initiation regimen, autophagy was induced concomitantly with a fall in plasma insulin in the presence of stable glucagon levels, resulting in a robust amino acid release. In liver-specific autophagy (Atg7)-deficient mice, no amino acid release occurred and blood glucose levels continued to decrease in contrast to those of wild-type mice. Administration of serine (30 mg/animal) exerted a comparable effect, raising the blood glucose levels in both control wild-type and mutant mice under starvation. Thus, the absence of the amino acids that were released by autophagic proteolysis is a major reason for a decrease in blood glucose. Autophagic amino acid release in control wild-type livers was significantly suppressed by the prior administration of glucose, which elicited a prompt increase in plasma insulin levels. This indicates that insulin plays a dominant role over glucagon in controlling liver autophagy. These results are the first to show that liver-specific autophagy plays a role in blood glucose regulation.     

Refrex-1, a Soluble Restriction Factor against Feline Endogenous and Exogenous Retroviruses

The host defense against viral infection is acquired during the coevolution or symbiosis of the host and pathogen. Several cellular factors that restrict retroviral infection have been identified in the hosts. Feline leukemia virus (FeLV) is a gammaretrovirus that is classified into several receptor interference groups, including a novel FeLV-subgroup D (FeLV-D) that we recently identified. FeLV-D is generated by transduction of the env gene of feline endogenous gammaretrovirus of the domestic cat (ERV-DCs) into FeLV. Some ERV-DCs are replication competent viruses which are present and hereditary in cats. We report here the determination of new viral receptor interference groups and the discovery of a soluble antiretroviral factor, termed Refrex-1. Detailed analysis of FeLV-D strains and ERV-DCs showed two receptor interference groups that are distinct from other FeLV subgroups, and Refrex-1 specifically inhibited one of them. Refrex-1 is characterized as a truncated envelope protein of ERV-DC and includes the N-terminal region of surface unit, which is a putative receptor-binding domain, but lacks the transmembrane region. Refrex-1 is efficiently secreted from the cells and appears to cause receptor interference extracellularly. Two variants of Refrex-1 encoded by provirus loci, ERV-DC7 and DC16, are expressed in a broad range of feline tissues. The host retains Refrex-1 as an antiretroviral factor, which may potentially prevent reemergence of the ERVs and the emergence of novel ERV-related viruses in cats. Refrex-1 may have been acquired during endogenization of ERV-DCs and may play an important role in retroviral restriction and antiviral defense in cats.     

Optimization of conditions for thermal treatment of rice bran using an accelerator including an organo-iron compound

A method for thermal conversion of raw organic waste (ROW) to a compost-like material (CLM) with higher levels of unsaturated carbohydrates, nitrogen- and oxygen-containing compounds was developed, in which rice bran and an organo-iron compound were employed as a model ROW and the accelerator, respectively. To evaluate the qualities of CLMs, organic substances of an acid insoluble fraction of alkaline extracts (AIAEs) from a CLM were structurally characterized by elemental analysis, pyrolysis-gas chromatography/mass spectrometry and FT-IR. The levels of unsaturated carbohydrates, and nitrogen- and oxygen-containing compounds in the CLM samples were increased by long-term treatment (60°C for 5 days, 170°C for 3 days). In particular, the high lipid content of the AIAEs, which was indicative of inadequate digestion of CLM components, was dramatically reduced in the presence of the accelerator.