Improvement of thermal stability of Streptomyces cholesterol oxidase by random mutagenesis and a structural interpretation

Random mutagenesis was used to enhance the thermal stability of Streptomyces cholesterol oxidase. Four thermostable mutants were isolated and the following amino acid substitutions were identified: Ser103 to Thr (mutant S103T), Val121 to Ala (mutant V121A), Arg135 to His (mutant R135H) and Val145 to Glu (mutant V145E). The wild-type and mutant enzymes were purified and characterized. The properties of mutants S103T, V121A and R135H were similar to those of the wild type but they showed improved thermal stability. When the V145E mutation was introduced, the thermal stability of the enzyme was markedly increased and the optimum pH was desirably changed to encompass a broad range from acid to alkali. Analysis of multiple mutants constructed by site-directed mutagenesis showed that all the mutations except that of R135H had an additive influence on the other mutations. These mutational effects are discussed in terms of a three-dimensional structural model of the enzyme constructed on the basis of homology modelling.

Molecular and phylogenetic analyses of the haemagglutinin (H) proteins of field isolates of canine distemper virus from naturally infected dogs

We isolated three strains of canine distemper virus (CDV)--the Ueno, Hamamatsu, and Yanaka strains--from dogs in Japan and analysed the molecular properties of their haemagglutinin (H) proteins. Immunoprecipitation of all three strains with a monoclonal antibody revealed H proteins with molecular masses of 84 kDa, which differs from the molecular mass (78 kDa) of the H protein of the Onderstepoort vaccine strain. However, after tunicamycin treatment immunoprecipitation identified H proteins of identical molecular mass (68 kDa) for all three field isolates and the vaccine strain. Sequence analysis showed nine potential sites for asparagine-linked glycosylation in the H proteins of the new isolates, in contrast to four in the H protein of the Onderstepoort strain. Thus, variation in glycosylation of the H proteins of the isolates and the vaccine strain may cause differences in antigenicity of the viruses. Sequences of the H genes showed that the new Japanese isolates have 99% identity with each other, 95% with other European and American isolates (from seals, a German dog, a ferret and large felids) and 90% with the vaccine strain. Phylogenetically, the new Japanese isolates form one cluster which is separate from recent European or American isolates, all of which are distinct from vaccine strains.

Structural studies of mitomycins. VIII. Mitomycin D hydrate, C15H18N4O5.1.5H2O

The title compound, [1aS]-6-amino-1, 1a,2,4,7,8,8a,8b-octahydro-8a-hydroxy-1,5-dimethyl-4,7-dioxoazirino++ +[2',-3': 3,4]pyrrolo[1,2-a]indol-7-ylmethyl, is a mitomycin derivative, mitomycins being antitumor antibiotics. The O atoms of the quinone ring deviate significantly from the least-squares plane through the quinone ring.

Structural studies of mitomycins. VII. Mitomycin G

The title compound, [1aS-(1a alpha, 8a alpha, 8b alpha)]-6-amino-1, 1a,2,8,8a,8b-hexahydro-8a-methoxy-1,5-dimethyl-8-methyleneazirino [2',3':3,4]pyrrolo[1,2-a]indole-4,7-dione, C15H17N3O3, is a derivative of the mitomycins, which are antitumor antibiotics. The quinone O atoms deviate significantly from the least-squares plane of the quinone ring.

Use of ELISA for in vitro potency test of rabies vaccines for animal use

The use of ELISA for the potency test of inactivated rabies vaccines for animal use was evaluated. Sandwich ELISA was developed, using monoclonal antibodies which enabled to recognize the glycoprotein (G-protein) of rabies virus and showed a protective effect in mice. Soluble G-protein which displays an ELISA activity but a low immunogenicity was removed by gel filtration before ELISA was carried out. The ELISA titres of the first fraction of vaccines separated by gel filtration were correlated with the neutralizing antibody titres of vaccinated guinea-pigs. Our results suggest that the ELISA titres of the first fraction of vaccines separated by gel filtration reflected the protective G-protein contents for the in vitro potency test of rabies vaccines compared with the current in vivo test.

Increased plasma adrenomedullin in acute myocardial infarction

Adrenomedullin has a potent vasodilating effect comparable to that of calcitonin gene-related peptide. To investigate the pathophysiologic role of endogenous adrenomedullin, we determined sequentially the plasma adrenomedullin level in 15 consecutive patients with acute myocardial infarction (AMI). Plasma adrenomedullin was higher immediately after the onset of AMI and decreased gradually; plasma levels during the 3-week period after the AMI were higher than plasma levels in 15 healthy control subjects (p < 0.001), with higher levels in patients with congestive heart failure than in patients without congestive heart failure throughout the period of the study (p < 0.05). Plasma adrenomedullin was positively correlated with pulmonary capillary wedge pressure, pulmonary arterial pressure, right atrial pressure, and heart rate in the early stage of AMI. These findings suggest that the elevation of plasma adrenomedullin is related to the retention of body fluid volume, the enhancement of sympathetic activity, and/or the elevation of pressure in pulmonary vascular beds. Adrenomedullin may act against excessive vasoconstrictors increased in AMI.

Microchimerism in female renal transplant recipients from male donors

Microchimerism in 23 female renal transplant recipients from male donors was studied using nested polymerase chain reaction (nPCR) and fluorescence in situ hybridization (FISH) to detect Y-chromosome. nPCR was a sensitive and specific assay enabling a detection rate of 1/10(6) male/female cells, compared with a sensitivity of 1/10(2) by standard PCR (sPCR). None of the 23 patients with a male allograft demonstrated Y-chromosome using sPCR. In contrast, 1 3 (56.5%) patients demonstrated Y-chromosome with nPCR. Of 9 patients proven to have microchimerism by nPCR, only 3 also demonstrated Y-chromosome using FISH. The existence of B cells and CD8 cells in donor chimeric cells were proved by separation with Dynabeads class I and class II. Dynamic changes of microchimerism occurred in 4 of 5 patients. Four patients were proven to have microchimerism within a year of transplantation and the microchimerism later disappeared in 3, although the sequential change was variable in individual patients. There was no correlation between microchimerism and patients'clinical factors such as donor-specific blood transfusion, HLA matching, immunosuppression, past history of acute rejection and chronic rejection. The degree of microchimerism in renal transplant recipients was relatively low, and its existence did not seem to be compatible with long-term graft acceptance. However, further studies are required to elucidate the immunological mechanism of microchimerism, and it might be an important clue to immunological tolerance.

[A structure based pharmaceutical database for drug interactions]

A structure-based pharmaceutical database for drug interactions has been developed. This database is based on the ISIS/Desktop and the Microsoft Access relational database system for Windows. Data of Japanese accepted name, molecular formula, molecular weight, CAS registry number, therapeutic category index code, structural formula, Japan ethical drugs code, side effects information, drug interactions information were taken from "Japanese Accepted Names for Pharmaceuticals 1992", "Drugs in Japan Ethical Drugs 1993" and "Drug Intelligence Reinforce".

Developmental defects of lymphoid cells in Jak3 kinase-deficient mice

Jak3 is a tyrosine kinase mediating cytokine receptor signaling through the association with the common gamma chain of the cytokine receptors such as IL-2, IL-4, IL-7, IL-9, and IL-15. Unlike other members of the Jak family, the expression of Jak3 is highly restricted in hematopoietic cells. To elucidate in vivo function of Jak3, Jak3-deficient mice were generated by homologous recombination. Mice homozygous for Jak3 null mutation showed severe defects, specifically in lymphoid cells. B cell precursors in bone marrow, thymocytes, and both T and B cells in the spleen drastically decreased, although these defects were significantly recovered as aging occurred. Peripheral lymph nodes, NK cells, dendritic epidermal T cells, and intestinal intraepithelial gamma delta T cells were absent. Normal number of hematopoietic stem cells in bone marrow from Jak3-deficient mice and the similar capability to generate myeloid and erythroid colonies as wild-type mice indicated specific defects in lymphoid stem cells. Furthermore, the abnormal architecture of lymphoid organs suggested the involvement of Jak3 in the function of epithelial cells. T cells developed in the mutant mice did not respond to either IL-2, IL-4, or IL-7. These findings establish the crucial role of Jak3 in the development of lymphoid cells.

The SMXA: a new set of recombinant inbred strain of mice consisting of 26 substrains and their genetic profile

A new set of recombinant inbred (RI) strain SMXA consisting of 26 substrains was established between SM/J and A/J. The history of the SMXA RI strains and their genetic profile covering 158 genetic marker loci are reported. From the strain distribution pattern among SMXA RI strains, the chromosomal location of salivary and tear protein genes Spe1-r, Spe1-s, Spe2, and Tpe1 were newly determined.

[Isolation of nontuberculous mycobacteria during colonoscopy]

We conducted a survey on nontuberculous mycobacteria (NTM) isolated in association with colonscopy at two hospitals. NTM was isolated from the fluid-phase of colonic contents in 17.6% of the specimens obtained at hospital A and in 46.3% at hospital B. The rate of isolation from the preexamination suction fluid was 9.5% and 43.3% at hospital A and B, respectively. Tap water samples from both hospitals were examined and proved to be free from contamination with NTM. The mycobacterial species isolated at hospital A were M. chelonae subsp. abscessus, M. chelonae subsp. chelonae, M. fortuitum, and M. gordonae. M. chelonae subsp. abscessus was the only mycobacterial species isolated at hospital B. M. avium complex was not isolated at either hospital. By an additional procedure to cleans and decontaminate the endoscopes by suction with Maskin ethanol solution, the incidence of isolation of NTM from the fluid-phase of colonic contents was significantly reduced. None of the patients from whom NTM was isolated exhibited positive signs of colonic NTM infection by the endoscopic examination and non had any underlying diseases which might induce immune suppression. We suspect that most of the NTM isolates have originated from the contaminated endoscope. In conclusion, when a colonscopic examination is carried out in suspicion of NTM disease in intestine, it is essential to reassess the possibility of mycobacterial contamination of the colonscopes and implement appropriate steps for cleansing and sterilization of them.

[Contamination of flexible fiberoptic bronchoscopes with Mycobacterium chelonae linked to an automated endoscope disinfection machine--on the relationship between the presence of the organism in the intestinal tract and contamination of disinfection machine, and a case of gallbladder and bile duct infection with M. chelonae]

In 1993, thirteen strains (8.7%) of M. chelonae were isolated from bronchoalveolar lavage fluid (BALF) obtained by bronchoscopy of 150 patients in Tachikawa-sogo (T) hospital, where the same automated disinfection machine was commonly used for cleaning, sterilization and disinfection of fiberbronchoscope and fibercolonoscope except 3 bronchoscopes disinfected by gas sterilization. Since January 1994, manual cleaning and sterilization has been applied for bronchoscope, and thereafter no strain of M. chelonae was isolated from BALF of 55 patients in the T hospital. While only one strain (3%) of M. chelonae was isolated from BALF of 33 patients in Ota (O) hospital, but many strains of M. chelonae were isolated from intestinal fluid obtained by fibercolonoscopy of the patients. Manual method of cleaning and disinfection was performed for both bronchoscopes and colonoscopes in the O hospital from the beginning. Based on these results, it was suggested that M. chelonae are commonly present in the colon (intestine) of normal persons. Thus colonoendscope may be often contaminated with the organism and subsequently the automated disinfecting machine may also be contaminated with the organism which is resist and against usual disinfection procedure, and resulted in bronchoscope contamination. If the presence of M. chelonae in intestinal tract is not rare, bile duct may be naturally infected with the organism. A case of cholecystitis and cholangitis caused by M. chelonae, which has not been reported previously, was found in the T hospital.