Alteration of infection pattern of duck hepatitis B virus by immunomodulatory drugs

The relationship between host immune state and hepatic inflammation and infection pattern of the Duck hepatitis B virus (DHBV) was investigated by experimental transmission of DHBV into 98 Japanese 7-day-old ducklings that had been pretreated with immunoregulatory drugs including cyclophosphamide, OK 432, and a steroid hormone. Immunosuppressive treatment with cyclophosphamide revealed an extension of the viremic period associated with an absence of inflammatory changes in the liver. Although immunostimulating treatment with OK 432 showed a remarkable accumulation of inflammatory cells in the liver, the viremic period was not shortened. Treatment with a steroid used as a immunosuppressant did not suppress the hepatitis; moreover, it increased viral DNA replication and extended the viremic period. This phenomenon of viral replication seemed to be caused by the direct effects of the steroid. Alteration of DHBV infection by modifying the host immune state is quite similar to that of hepatitis B virus (HBV) in humans. In DHBV infection, the host immune state seemed to have a considerable role in determining the infection pattern and degree of hepatitis activity. DHBV may be a helpful model of HBV for studying host-viral interaction and the immunological mechanism of viral hepatitis.

Genetic mapping of the Escherichia coli gene for the stringent starvation protein and its dispensability for normal cell growth

To determine its map position, the sSP gene was cloned into plasmid pBR322 and the recombinant plasmid was integrated into the chromosome of a polA mutant at the site of the sSP gene by homologous recombination. The chromosomal location of Ampr was then determined by P1 phage-mediated transduction. Thus, the sSP gene was mapped between gltB and glnF at min 69.5 on the Escherichia coli chromosome. Strains were constructed in which the sSP gene was brought under the control of the lac regulatory system. This indicated that the stringent starvation protein (SSP) is dispensable for growth, at least under normal culture conditions.

Geographical pathology of duck livers infected with duck hepatitis B virus from Chiba and Shimane in Japan and Shanghai in China

In order to evaluate geographical differences in the liver pathology of ducks infected with duck hepatitis B virus (DHBV), ducks in Chiba and Shimane, Japan, and Shanghai, China, were investigated. The numbers (DHBV positive/negative) and the maximum age of the ducks examined were 18/10 at 19 mo, 15/1 at 3 yr 4 mo, and 72/27 at 18 mo, respectively. DHBV infection was induced experimentally in ducks from Chiba and Shimane but was present congenitally in those from Shanghai. Ducks were examined regarding liver function tests, conventional histology, immunohistology, electron microscopy, and molecular hybridization for DHBV DNA in the serum and liver. There was no significant difference between DHBV-positive and -negative ducks in bilirubin and transaminase and alkaline phosphatase activities in the sera. Histologically, while the livers of ducks from Chiba and Shimane did not show necroinflammatory (hepatitis) activity, those from Shanghai frequently did (52.5%). Necroinflammatory activity of the Shanghai ducks was present almost equally in both DHBV-positive and -negative livers. The livers of Shanghai ducks but not the other two areas often (8.3%) had ground-glass inclusions which corresponded ultrastructurally to numerous virus particles in the dilated cisternae of the proliferated endoplasmic reticulum. No advanced liver disease, such as cirrhosis or hepatocellular carcinoma, was observed. There was no significant difference in the amount of DHBV DNA in the sera or in its pattern in the liver tissue among ducks of the three areas. In addition, the livers of Chiba ducks frequently had amyloidosis, while those of Shanghai ducks were contaminated with parasites. In conclusion, DHBV infection did not appear to provoke significant hepatitis activity or advanced liver disease in the examined ducks of all three areas, and the DHBV-positive livers from Shanghai ducks showed a different morphological appearance from those of the other two areas. This variation might reflect the difference in the strain of ducks, subtypes of DHBV, environmental factors, or a combination of these influences.

A sequential study of viral DNA in serum in experimental transmission of duck hepatitis B virus

To understand the relationship among the time of infection, infection patterns, and liver diseases, experimental transmission of duck hepatitis B virus (DHBV) utilizing 165 Japanese white domestic ducklings was performed. Twenty to 25 ducklings were each inoculated with DHBV-positive serum intravenously at day one, 3, 5, 7, 10, and 14 posthatch and were sacrificed during the 1st, 2nd, 3rd, and 4th (and 24th in those inoculated on day one and day 3 posthatch) week after inoculation to obtain sera and the liver. The sera served for the measurement of DHBV DNA by spot hybridization test and DNA polymerase activity, and the liver was subjected to morphological examination including immunostaining for DHBV. The ducklings inoculated with DHBV on 1 day and 3 days posthatch always revealed persistent viremia, whereas those on and after 5 days posthatch showed persistent or transient viremia. The hepatitis activity in the liver was seen in ducklings inoculated with DHBV on and after 3 days posthatch and was very weak consistent with the diagnosis of mild acute hepatitis of humans. The serum transaminase activity was not significantly elevated at the time of occurrence of histological hepatitis activity. Since host immune mechanism establish at 3 to 5 days posthatch in birds, the host immune response seemed to determine whether DHBV infection was persistent or transient and the occurrence of hepatitis activity as seen in human hepatitis B virus (HBV) infection.

Structure of the gene for the stringent starvation protein of Escherichia coli

The nucleotide sequence of the gene for the stringent starvation protein (SSP) of E. coli was determined. The deduced amino acid sequences shows that the SSP is composed of 212 amino acid residues, rich in both positively and negatively charged amino acids and has a molecular weight of 24,305. Primer extension experiments and nuclease S1 mapping analysis showed a site on the chromosome DNA corresponding to the 5' end of the transcript of the SSP gene. However, the consensus promoter sequences were not found at the upstream region. In the 3' flanking region a long coding frame was found immediately following the SSP gene, suggesting that the SSP gene is a member of a multicistronic operon.

Gastric emptying in deformed stomach

To evaluate the relationship between the onset of peptic ulcer and gastric emptying, some factors which were thought to regulate gastric emptying, i.e. the stage of the ulcer, the location of the ulcer and gastric acidity were studied in cases of gastric ulcer with deformed stomach and were proven to have little influence on gastric emptying. Further, the main cause of delayed gastric emptying was revealed to be the deformity itself, because the shortening of the distance from the gastric angle to the pyloric ring at the lesser curvature (sac-shaped stomach) and the indentation of the corpus ventriculi (hourglass-shaped stomach) significantly delayed gastric emptying. Moreover, it was found that the healing of gastric ulcer was delayed in cases of deformed stomach with delayed gastric emptying when the ulcer was at an active stage. Therefore the improvement of gastric emptying by some methods was thought to be necessary to promote ulcer healing and prevent ulcer recurrence in gastric ulcer patients who had a deformed stomach.

Cloning of the Escherichia coli gene for the stringent starvation protein

In order to clone the Escherichia coli gene for the stringent starvation protein (SSP), we determined its N-terminal sequence as well as the sequence of two peptide fragments obtained by cyanogen bromide cleavage of the protein. We then chemically synthesized four sets of oligodeoxyribonucleotide mixtures that represented possible codon combinations for parts of these amino acid sequences. The synthetic oligonucleotides were labelled with 32P at their 5'-termini and used as hybridization probes to detect DNA fragments containing the complementary sequences. Genomic Southern hybridization of E. coli chromosomal DNA gave up to ten DNA fragments hybridizing with each probe but only a few hybridized with two or more of the probes. The latter fragments were cloned in pBR322. By determining partial base sequences with a rapid method and examining proteins encoded by the DNA fragments, we were able to show that we had isolated a clone containing the complete SSP structural gene.

Determination of streptomycin in serum by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for monitoring the serum concentration of streptomycin. The method includes clean-up using a Sep-Pak C18 cartridge and quantitation using dihydrostreptomycin as an internal standard. Streptomycin and dihydrostreptomycin were separated by reversed-phase ion-pair chromatography on LiChrosorb RP-18 and detected by UV absorption (195 nm). The calibration graph of serum streptomycin concentration was linear over the range 5-50 micrograms/ml. Streptomycin was added to serum at the level of 20.0 micrograms/ml and its concentration was determined to be 18.9 micrograms/ml with a coefficient of variation of 2.07% (n = 5). The clinical application of this method was confirmed by comparison with fluorescence polarization immunoassay.

Transcription and replication of eight RNA segments of influenza virus

A novel quantitation system of both plus- and minus-strand RNAs for all eight genome segments of influenza virus was developed using single-strand cDNAs as the probes for hybridization, and employed for the measurement of various RNA species in influenza virus WSN-infected MDBK cells. The synthesis rate and accumulation level of plus-strand RNAs differed considerably among eight RNA segments and were under temporal control. In contrast, eight vRNA molecules of minus polarity were synthesized coordinately at similar rates. Newly synthesized plus-strand RNAs were rapidly transported into the cytoplasm, particularly during the early phase of virus infection, but vRNAs accumulated in the nuclei until the late infection phase. The present data supported the differential regulation of synthesis and the separate transport between plus- and minus-strand RNAs.

Effects of diltiazem on plasma level and urinary excretion of digoxin in healthy subjects

To evaluate a possible effect of diltiazem hydrochloride (DTZ) on digoxin (DX) kinetics, we performed a study in which a single oral dose of DX (0.5 or 0.75 mg) was given with and without DTZ (30 mg three times daily for 1 wk) to six healthy subjects. DTZ increased plasma DX concentrations at 3, 4, 6, and 12 hr and decreased renal clearance of DX from 3.05 +/- 0.126 to 2.31 +/- 0.234 ml/min/kg. There was no significant change in absorption t 1/2, peak concentration, peak concentration time, distribution t 1/2, biologic elimination t 1/2, or apparent volume of distribution with DTZ.

Mechanism of the rifampicin induction of RNA polymerase beta and beta' subunit synthesis in Escherichia coli

The mechanism of the rifampicin induction of RNA polymerase beta and beta' subunit synthesis was investigated, employing an in vitro coupled system of transcription and translation as well as an in vitro transcription system with purified RNA polymerase holoenzyme. Two independent effects leading to the induction of beta and beta' polypeptide synthesis have been identified for the drug: 1) rifampicin binds to RNA polymerase holoenzyme and inhibits its autorepressor activity, thus relieving the autorepression exerted possibly on the translation of rpoBC mRNA; and 2) rifampicin-RNA polymerase complex functions as a positive effector stimulating the transcription of rpoBC genes, but not of rplL gene. Using a terminally labeled DNA fragment covering the intercistronic region between rplL and rpoB as a probe, the structure of both in vivo and in vitro RNA were analyzed by S1 nuclease-mapping assays. The experimental results indicated that the observed stimulation of the transcription by rifampicin was attributed, at least in part, to relaxation of the transcription attenuation immediately preceding the rpoB gene, resulting in the increase of the read-through transcript to rpoBC genes. Besides the read-through transcript and the processed mature rpoBC mRNA, another RNA species was found in in vivo RNA, which might be transcribed from a weak promoter located in the intercistronic region. However, no clear indication has been obtained of possible enhancement of the transcription initiation by rifampicin from the putative promoter.

Milbemycins, a new family of macrolide antibiotics: fermentation, isolation and physico-chemical properties

A search for novel insecticides has yielded the milbemycins, a new family of macrolide antibiotics with insecticidal and acaricidal activity. They are produced in submerged cultures of Streptomyces hygroscopicus subsp. aureolacrimosus. Fermentation studies on the strain were conducted in shaken flasks and 30-liter jar fermentors. From the culture broth 13 milbemycins were purified to homogeneity by column and thin-layer chromatography on silica gel and alumina. Physico-chemical data, such as mass spectra, UV and IR absorption spectra, optical rotations and melting points of the milbemycins are described.