[Refractory acute myelogenous leukemia successfully treated with a continuous infusion chemotherapy of low dose aclarubicin and cytosine arabinoside: a case report]

A 44-year-old female with refractory acute myelogeneous leukemia had experienced an early relapse after a third complete remission (CR) with combination chemotherapy (BHAC-AMP) using daily one-shot infusion of 20 mg aclarubicin (ACR). Further treatments including intermediate dose of cytosine arabinoside (Ara-C) were not effective. After treatment with a continuous administration of low dose ACR (9 mg/day) and Ara-C (21 mg/day) for 14 days she entered a fourth CR. The mechanism of this treatment relates to both cell-killing and differentiation effects on leukemic cells.

Pericentric region of chromosome 9 is a possible candidate region for linkage study of schizophrenia

We have undertaken a systematic G-banding survey to find structural chromosomal abnormalities among patients with schizophrenia. Of 120 patients with DSM-III-R schizophrenia, four (3.3%) had a pericentric inversion of chromosome 9 and three (2.5%) had a X/XX mosaicism. The frequency of pericentric inversion of chromosome 9 among patients with schizophrenia was statistically higher than those among newborns and Asian populations. Our results indicate that the pericentric region of chromosome 9 might be one of the potential regions of interest for linkage analysis of schizophrenia.

Inflammation of the liver causes mutations in duck hepatitis B virus genome

To investigate whether hepatitis causes mutation in the viral genome, DNA sequences in the pre-core region of duck hepatitis B virus (DHBV) DNA were analyzed in both ducks with hepatitis and without hepatitis. Five DHBV carrier ducks were injected with DHBV particle proteins purified from duck serum with Freund's complete adjuvant (FCA) intrahepatically from 14 day posthatch for 9 weeks (immunized group). Serum was drawn at the end of the 1st and 4th week after the 1st injection of DHBV particle protein and ducks were killed at the end of the 9th week to obtain the liver. Another five ducks without treatment were used as controls. All ducks of the immunized group showed moderate to severe hepatitis at the 9th week. All ducks in the immunized group showed one mutation except one duck that showed two mutations only at the 9th week. Mutations were observed in the 5th, 13th, 21st, 22nd, and 28th codon of the pre-core region. All of them were point mutation at the 3rd base in the triplets. The frequency of mutation was different in each duck from 20% to 60% but not 100%. There was no mutations in ducks in control group. These results suggest that hepatitis causes mutation in the pre-core lesion genome of duck hepatitis B virus.

Binding of influenza A virus NS1 protein to dsRNA in vitro

The non-structural protein NS1 of influenza A virus exhibits two modes of RNA-binding activity. One is sequence-specific binding to minus-sense virus RNA with either a 5'- or 3'-terminal common sequence as reported previously. The other was identified as binding to dsRNA and this activity did not show sequence specificity. The affinity of binding to dsRNA was much higher than that to ssRNA. A short miniature virion RNA forming a panhandle structure by pairing between the 5'- and 3'-terminal common sequences bound NS1 with higher affinity and stability than did a dsRNA of similar sequence and length.

The sequential change of serum 2',5' oligoadenylate synthetase in different infectious patterns of duck hepatitis B virus in ducks in experimental transmission

Duck hepatitis B virus (DHBV) shows clear age-dependent infectious patterns like that of Hepatitis B virus, and many factors have been assumed to have a role in the persistence of the infection. In the present study, the activities of the interferon-induced enzyme 2',5' oligoadenylate synthetase (2,5AS) were observed sequentially in the serum of ducks experimentally infected with DHBV on posthatch days 1, 7 and 14. These were compared with the infectious pattern to investigate whether the endogenous interferon response after infection in ducks of different ages has a major role in its determination. The infectious pattern of DHBV in 1-day-old ducks was persistent without hepatitis and the others were transient with hepatitis. Persistently infected ducks showed significantly lower activities of 2,5AS compared with those with transient hepatitis, which resulted in a rapid elimination of DHBV. Although 1-day-old ducks showed significantly high 2,5AS compared with non-infected ducks, interferon response alone appeared to be insufficient for the elimination of DHBV. The immune response seemed necessary for the complete elimination of DHBV by way of evoking hepatitis and stimulating more interferon response during the usual infectious course. The interferon system alone did not seem to have a critical role in determining the infectious pattern. Other factors, including the immune response to the virus, seemed to have a major role in this problem.

[Attempt to cause hepatitis in duck hepatitis B virus carrier ducks by immunization with DHBV protein]

In order to investigate the hypothesis that viral hepatitis is a host immune response against viral protein presented on hepatocytes, we attempted to cause hepatitis in DHBV carrier ducks by immunization with DHBV protein. While ducks injected with Freund Complete Adjuvant (FCA) showed only weak hepatitis, those immunized with DHBV particle protein showed severe hepatitis. This same procedure could not cause significant inflammation in the liver of ducks without DHBV infection. The severity of hepatitis was well associated with the frequency of the immunization. However, the degree of hepatitis activity was different among same times immunized ducks. Occurrence of hepatitis assumed to have close association with host immune response against viral protein.

Specific binding of influenza A virus NS1 protein to the virus minus-sense RNA in vitro

The non-structural protein NS1, encoded by genome segment 8 of influenza A virus, was expressed in Escherichia coli from cloned cDNA and purified. The NS1 protein had a specific RNA-binding activity, binding to influenza A virus minus-sense but not plus-sense RNA synthesized in vitro from cloned DNA using phage RNA polymerase. NS1 bound preferentially to the regions of RNA containing either 5'- or 3'-terminal common sequences of the genomic RNA. Binding was inhibited by virion RNA, but not by single-stranded minus-sense cDNA and oligo DNAs having the common sequences. In addition, binding was also inhibited by 28S rRNA but not 18S rRNA prepared from MDCK cells.

Involvement of the influenza A virus PB2 protein in the regulation of viral gene expression

To determine the function(s) of the PB2 protein of influenza A virus, six temperature-sensitive (ts) mutants of A/Udorn/72 (H3N2) virus, each carrying a ts mutation in the PB2 gene, were analysed for virus RNA and protein synthesis. One of the mutants, ICRC27, exhibited unique phenotypes and was characterized in detail. At the non-permissive temperature, 40 degrees C, the accumulation of mRNA for each genome segment was reduced severely, leading to delayed and reduced synthesis of viral proteins, complementary and viral RNAs (cRNAs and vRNAs). At the permissive temperature, 34 degrees C, the mutant virus produced several-fold greater concentrations of both mRNAs and cRNAs of PB2, PB1 and PA segments than wild-type virus. The synthesis of the three polymerase proteins and the induction of RNA polymerase activity were also greatly increased. By contrast, the expression of the haemagglutinin (HA) gene was severely suppressed. The over-production of the polymerase mRNAs was not observed during primary transcription, i.e. in the presence of cycloheximide. The ts+ revertants of ICRC27 did not exhibit the ts defects and also lost most of the non-ts phenotypes at 34 degrees C. These observations indicate that the PB2 protein participates not only in the synthesis of viral RNAs, but also in the regulation of viral gene expression, i.e. in the down-regulation of the three polymerase genes and the up-regulation of the HA gene during secondary transcription.

Analysis of influenza A virus temperature-sensitive mutants with mutations in RNA segment 8

Temperature-sensitive (ts) mutants of influenza virus strain A/Udorn/72 (H3N2 subtype) with lesions in RNA segment 8 exhibited intrasegmental complementation, and were divided in two complementation groups (H1 and H2) on MDCK cells. The nucleotide sequence of segment 8 was determined for three of these mutants. The H1 strains, ICR1629 and SPC45, have a single amino acid substitution in the coding region of the non-structural protein NS1, whereas the H2 strain, ICR516, has a substitution in the NS2-coding region. With both NS1 ts mutants, the synthesis of two late proteins, the matrix protein (M1) and haemagglutinin (HA), was greatly reduced and NS1 synthesis also decreased at 40 degrees C (non-permissive temperature) compared to that at 34 degrees C (permissive temperature). The synthesis of each virus-specific RNA was analysed using a quantitative hybridization method. However, at 40 degrees C, the levels of individual mRNAs including those for the late proteins, were almost the same as those at 34 degrees C, and attained the wild-type levels later in the infection (5 h post-infection) when the synthesis of the late proteins and the NS1 protein was severely reduced. The observations suggest that the NS1 protein, which is a nuclear protein, is involved in some post-transcriptional processes in the synthesis of the late proteins and the NS1 protein.

Control of influenza virus gene expression: quantitative analysis of each viral RNA species in infected cells

We established a quantitative hybridization system by which three types of influenza virus RNAs (vRNA, mRNA, and cRNA) for the 8 genome segments were measured individually. As the hybridization probes, 32P-labeled RNAs of both plus and minus polarity were produced employing an SP-6 transcription system and used in a large molar excess, sufficient to overcome complementary RNAs present in the viral RNA samples. Employing the system, we studied the control of the synthesis of each viral RNA species in MDCK cells infected with A/Udorn/72 (H3N2). Our new observations were as follows. 1) Segment-specific transcription was observed at the primary transcription. 2) Replication of the virus genome began simultaneously for all segments. No delay was observed in the replication of the segments carrying late genes. 3) In addition to control at the transcriptional levels, the expression of viral late genes was regulated at some post-transcriptional step(s). These results are not compatible with the concepts reported previously, and lead us to propose unique regulations operating on the expression of the viral late genes.

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.