Selective interaction of hsp90 with an estrogen receptor ligand-binding domain containing a point mutation

The 90-kDa heat shock protein (hsp90) has been implicated in modulating steroid receptor function in vitro and in vivo. Previous studies have suggested that hsp90 interacts with large portions of the estrogen receptor (ER) ligand-binding domain and sequences of the receptor required for stable DNA binding. To characterize the interaction of the ER ligand-binding domain with hsp90, we have compared the properties of chimeras created by coupling the ligand-binding domain to the constitutive transactivator VP16-GAL. Two types of chimeras were created: VP16-GAL-ERG, containing the wild-type ligand-binding domain derived from the cDNA HEG0, and VP16-GAL-ERV, containing the substitution G400V derived from the ligand-binding domain of the original ER cDNA isolate, HE0. The G400V mutation alters the physical properties of VP16-GAL-ERV by rendering it hormone-dependent for DNA binding and more strongly dependent on estradiol for transactivation compared with VP16-GAL-ERG. Glycerol gradient analyses and chemical cross-linking/coimmunoprecipitation showed that, unlike VP16-GAL-ERG, VP16-GAL-ERV formed stable complexes with hsp90 in vitro. These data show that hsp90 selectively recognizes the altered ER ligand-binding domain containing the G400V substitution and indicate that the wild-type ER ligand-binding domain of VP16-GAL-ERG does not interact with hsp90 in vitro. Hormone binding studies showed that the ligand-binding domain of VP16-GAL-ERV was destabilized by incubation in the presence of high concentrations of salt or in the absence of sodium molybdate, conditions that disrupt its interaction with hsp90. The ligand-binding domain of the Val-400 ER thus behaves similarly to that of the wild-type glucocorticoid receptor, which has previously been shown to interact with hsp90 in vitro. These results provide evidence for the action of hsp90 as a molecular chaperone by selectively recognizing destabilized proteins.

Lactation, lactation suppression hormones and breast cancer

One hundred and fifty-four parous women with pathologically confirmed newly diagnosed breast cancer in National Taiwan University Hospital were selected as the case group. Three hundred and eighty-six parous inpatient controls were individually matched for each case by age and date of admission. Information was collected from questionnaire interview and medical record. Effects of lactation and lactation suppression hormone were assessed with conditional logistic regression analysis. In univariate analysis, lactation had a weak protective effect, after adjusting for educational level, body mass index, family history of breast cancer, reproductive factors, oral contraceptive and lactation suppression hormone use, the weak negative associations changed to weak positive ones. The use of lactation suppression hormone was consistently associated with a higher breast cancer risk. The major confounders between lactation and breast cancer risk were parity and age at first full-term birth. Lower breast cancer risks were found in high parity - long lactation, and in younger ages at first full-term birth - long lactation groups. The differences among different lactation lengths within each parity and age at first full-term birth category were small. The protective effects disappeared after adjusting for other potential confounders. The results of this study questions the independent protective effect of lactation in a population having both a variable duration of lactation and rapid socioeconomic change. The role of lactation suppression hormones needs further study.

The exchange between proglycogen and macroglycogen and the metabolic role of the protein-rich glycogen in rat skeletal muscle

The aim of this study is to determine if proglycogen and macroglycogen are kinetically related in rat skeletal muscle. Eight groups of anesthetized fasted rats (seven hepatic-occluded and one nonoccluded) were intravenously infused with [3-3H]glucose at a rate of 1.7 microCi x min(-1) for 20 min. At the end of infusion, hindlimb muscles were excised and rapidly frozen in liquid nitrogen. Proglycogen was extracted by precipitation in 10% TCA; and macroglycogen as a part of total glycogen by precipitation in 20% KOH-65% ethanol. Along with the tracer, the occluded rats were also infused with: saline (group 1); insulin at rates ranging from 5 to 50 mU x min(-1) (groups 2 to 5); and insulin at a rate of 10 mU x min(-1) plus glucose at rates of 10.2 and 20.4 micromol x min(-1), respectively (groups 6 and 7). The infusion regimens resulted in up to 30-fold difference in whole-body glucose utilization among the rats. In the rats infused with saline and insulin at a rate of 5 mU x min(-1), [3H]glucose was found to be exclusively incorporated into proglycogen. Incorporation into macroglycogen was found in the rats infused with insulin at rates > 10 mU x min(-1). Supplementary glucose infusion increased the synthesis of [3H]proglycogen (four- to sixfold), and equilibrated the two extractable forms of glycogen in the insulin-infused rats. In the saline-infused nonoccluded rats, only proglycogen was found to be labeled. In conclusion, our data indicate that in the intact and hepatic-occluded rats, proglycogen in the skeletal muscles may undergo synthesis and degradation of its own more readily than exchange between itself and depot macroglycogen.

Serotonin transporter antibodies: production, characterization, and localization in the brain

Serotonin (5-HT) transporter, the mechanism for 5-HT high affinity uptake, is the essential component for the termination of 5-HT transmission. In order to identify transporter sites on 5-HT neurons or on other 5-HT uptaking cells, three rabbit antisera against cocaine sensitive-serotonin transporter (5-HTT) were produced. Antisera 5-HTT55 (against amino acid sequence 55-68 in cytoplasmic N-terminal) and 5-HTT315 (against amino acid sequence 315-325, a 3rd external loop peptide) were produced against synthetic multiple-antigenic peptides (MAP). Antiserum 5-HTTN was produced against a fusion protein of the first 71 amino acids of N-terminal peptide expressed in recombinant DNA transformed bacteria. SDS-PAGE/Western blots indicate that 5-HTT55 and 5-HTT315 recognized bands of 74 and 64 kDa in rat brains with densities in the order of cortex > or = hippocampus > cerebellum, but not in liver, or muscle. The 5-HTTN recognized the fusion protein expressed in the bacteria, and the 64 kDa band with a similar density profile in the rat brain regions, and negative in liver and muscle. The immunocytochemistry of all three antisera revealed 5-HTT-immunostaining (5-HTT-im) in a pattern similar to 5-HT fiber distribution. 5-HTT55 and 5-HTT315 stainings were punctate in appearance, while 5-HTTN outlined the fibers in the 5-HT fiber areas, and neurons in raphe but not in substantia nigra or locus ceruleus. The preimmune serum and immune serum preabsorbed with 5-HTTN showed negative or diminished staining. Specific neurotoxin, 5,7-dihydroxytryptamine lesion removed all of the 5-HTTN fibers from the injection site, indicating, that 5-HTTN-im fibers are 5-HT fibers in nature. Our study indicates that the three antibodies we produced recognize various domains of the 5-HTT. Our 5-HTT antibodies could be used as new markers of 5-HT fibers, and are particularly useful for the study of the plasticity of 5-HT fibers free of the complications involved with 5-HT content.

Monocyte response to bacterial toxins, expression of cell surface receptors, and release of anti-inflammatory cytokines during sepsis

Exposure to endotoxin produces a state of macrophage hyporesponsiveness on subsequent stimulation. Monocytes in patients with septic shock demonstrate a similar hyporesponsiveness to endotoxin. The purpose of this study was to examine whether this state of hyporesponsiveness extends to other inflammatory stimuli and the relationship of this state to cell surface receptor expression and the release of anti-inflammatory cytokines. Twelve normal volunteers, 10 patients with severe sepsis, and 9 patients with septic shock were included in the study. Monocytes from each subject were isolated and stimulated with lipopolysaccharide (LPS), staphylococcal enterotoxin B (SEB), and phorbol myristate acetate (PMA). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were measured in the supernatants by enzyme-linked immunosorbent assay (ELISA). Serum levels of transforming growth factor-beta1 (TGF-beta1), prostaglandin E2 (PGE2), and interleukin-10 (IL-10) were also measured by ELISA. The expression of monocyte CD14 and HLA-DR in whole blood were measured by flow cytometry. Patients with septic shock demonstrated significantly decreased TNF-alpha and IL-1beta release as compared with normal subjects in response to LPS. In response to SEB, patients with sepsis and patient with septic shock demonstrated significantly decreased release of TNF-alpha and IL-1beta. Significant decreases in TNF-alpha release were found in the patients with septic shock after PMA stimulation. There were no significant differences in the monocyte response to the different stimuli between patients with gram-positive sepsis and gram-negative sepsis. HLA-DR expression was significantly decreased in patients with septic shock (58 +/- 9 fluorescence units (flU)) as compared with normal subjects (102 +/- 14 flU) (p < 0.05). No differences in CD14 expression were observed. IL-10 levels were significantly increased in patients with sepsis (16 +/- 4 pg/ml) and in patients with septic shock (42 +/- 15 pg/ml) and were detectable in 1 normal subject. TGF-beta1 levels were decreased in patients with septic shock (25 +/- 6 pg/ml) as compared with those in normal subjects (37 +/- 2 pg/ml)(p < 0.05). PGE2 levels were significantly increased in patients with septic shock and patients with sepsis. These data are consistent with a more generalized monocyte hyporesponsiveness to bacterial toxins that may be related to altered cell surface receptor expression and the release of anti-inflammatory cytokines.

[An experimental study on immune mechanism after alkali burn in the anterior segment of rabbit eye]

OBJECTIVE

To study the immunologic mechanism of corneal ulceration after alkali burn.

METHODS

55 rabbits with alkali burn in right eye were randomly divided into two groups. In group I (31 animals), the level of circulating immune complex (CIC), the rate of red blood cell C3b receptor complex rosette (RBC-C3bRR) and immune complex rosette (RBC-ICR) were measured respectively at 7, 14, 21, 35, 49 days after alkali burn. In Group 2 (24 animals), the immune complex was detected by means of immunofluorescence (IF) and immunogold-silver staining (IGSS) in burned tissues at 21 days after burn. Histopathologic changes were also observed under light microscope.

RESULTS

CIC, the rate of RBC-C3bRR and RBC-ICR were markedly increased 14 to 21 days after burn. In the mean time, the deposition of immune complex was found in burned tissues and the accumulation of polymorphonuclear leukocyte (PMN) was observed at the base of corneal ulcer.

CONCLUSIONS

The immune mechanism indeed participates in the pathogenesis of corneal ulceration and also aggravates the progress of ulceration on the base of chemical injury.

Human T cell leukemia virus type 1 tax protein increases NF-kappa B dimer formation and antagonizes the inhibitory activity of the I kappa B alpha regulatory protein

Human T cell leukemia virus type 1 (HTLV-1) encodes a strong transcriptional transactivator, the Tax protein, that stimulates viral transcription through the long terminal repeat and also stimulates many cellular genes via the activation of host transcription factors. Previous studies have demonstrated that Tax activates NF-kappa B through binding to the Rel homology domain of NF-kappa B proteins. Tax was also shown to increase degradation of I kappa B alpha resulting in the induction of NF-kappa B DNA binding activity. We addressed the specificity and function of Tax interaction with members of the NF-kappa B/I kappa B alpha family by using EMSA, protein affinity chromatography, protein-protein crosslinking and co-immunoprecipitation assays. The results of the present study demonstrate that: (1) Tax enhances NF-kappa B binding to DNA 40- to 100-fold by increasing NF-kappa B dimer formation which can be detected in the absence of DNA; (2) Tax binds to all NF-kappa B DNA binding subunits in vitro and to I kappa B alpha; (3) Tax physically associates with I kappa B alpha in vivo; and (4) Tax and I kappa B alpha have antagonistic effects on NF-kappa B binding and gene activity. These results suggest that Tax interaction with I kappa B alpha interferes with the formation of NF-kappa B-I kappa B alpha complexes and may play a role in targeting I kappa B alpha for degradation.

PAT1, an evolutionarily conserved acetyltransferase homologue, is required for multiple steps in the cell cycle

BACKGROUND

Acetylation has been implicated in many biological processes. Mutations in N-terminal acetyltransferases have been shown to cause a variety of phenotypes in Saccharomyces cerevisiae including activation of heterochromatin, inability to enter G0, and lethality. Histone acetylation has been shown to play a role in transcription regulation, histone deposition and histone displacement during spermatogenesis, although no known histone acetyltransferase is essential.

RESULTS

Studies aimed at revealing a role for histone H1 in yeast have uncovered a mutation in a putative acetyltransferase, PAT1. The mutant (pat1-1) cells can live only in the presence of vertebrate H1. PAT1 is essential for mitotic growth in S. cerevisiae; mutant cells depleted of the Pat1p show aberrant cellular and nuclear morphology. PAT1 is required for multiple cell cycle events, including passage through START, DNA synthesis, and proper mitosis through a microtubule-mediated process. The S. pombe PAT1 gene was cloned by complementation and shown to exist as part of a larger protein, the unique portion of which is homologous to a second S. cerevisiae gene. pat1 mutants show a variety of mitotic defects including enhanced chromosome loss, accumulation of multiple nuclei, generation of giant cells, and displays classical cut phenotypes in which cytokinesis occurs in the absence of proper nuclear division and segregation.

CONCLUSION

PAT1 controls multiple processes in cell cycle progression which suggests an essential role for the acetylation of yet unknown substrate(s).

Evaluation of tolerability and antibody response after recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and a single dose of recombinant hepatitis B vaccine

Recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) has been shown to augment antigen presentation by macrophages and dendritic cells in vitro, and to increase antibody responses to injected antigens in experimental animals. To evaluate the usefulness of rhGM-CSF as a vaccine adjuvant, 108 healthy volunteers were randomly assigned to receive an injection of rhGM-CSF (n = 81) or placebo (control group; n = 27), followed by an injection with recombinant hepatitis B vaccine into the same site. During the study period of 28 days, protective antibody titers to hepatitis surface antigen (anti-HBs10 mIU ml-1) were observed in 11 of 81 subjects receiving rhGM-CSF, but in none of the controls (P = 0.035). Injections were well tolerated. A single i.m. or s.c. injection of 20-40 micrograms of rhGM-CSF significantly enhances antibody responses when given at the same site as recombinant hepatitis B vaccination.

Transdominant mutants of I kappa B alpha block Tat-tumor necrosis factor synergistic activation of human immunodeficiency virus type 1 gene expression and virus multiplication

The human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) contains two binding sites for the NF-kappa B/Rel family of transcription factors which are required for the transcriptional activation of viral genes by inflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) and interleukin-1. In the present study, we examined the effect of transdominant mutants of I kappa B alpha on the synergistic activation of the HIV-1 LTR by TNF-alpha and the HIV-1 transactivator, Tat, in Jurkat T cells. The synergistic induction of HIV-1 LTR-driven gene expression represented a 50- to 70-fold stimulation and required both an intact HIV-1 enhancer and Tat-TAR element interaction, since mutations in Tat protein (R52Q, R53Q) or in the bulge region of the TAR element that eliminated Tat binding to TAR were unable to stimulate LTR expression. Coexpression of I kappa B alpha inhibited Tat-TNF-alpha activation of HIV LTR in a dose-dependent manner. Transdominant forms of I kappa B alpha, mutated in critical serine or threonine residues required for inducer-mediated (S32A, S36A) and/or constitutive (S283A, T291A, T299A) phosphorylation of I kappa B alpha were tested for their capacity to block HIV-1 LTR transactivation. I kappa B alpha molecules mutated in the N-terminal sites were not degraded following inducer-mediated stimulation (t1/2, > 4 h) and were able to efficiently block HIV-1 LTR transactivation. Strikingly, the I kappa B alpha (S32A, S36A) transdominant mutant was at least five times as effective as wild-type I kappa B alpha in inhibiting synergistic induction of the HIV-1 LTR. This mutant also effectively inhibited HIV-1 multiplication in a single-cycle infection model in Cos-1 cells, as measured by Northern (RNA) blot analysis of viral mRNA species and viral protein production. These experiments suggest a strategy that may contribute to inhibition of HIV-1 gene expression by interfering with the NF-kappa B/Rel signaling pathway.

[Clinical study of the pattern of lymphnode metastasis in carcinoma of esophagus: an analysis of 200 cases]

To study the pattern of lymphnode metastasis in carcinoma of the esophagus, 200 cases of resected esophageal cancer specimens were carefully examined pathologically. Lymphnode metastasis, its pathway and extent in relation to pathological changes were analyzed. Lymphnode metastasis was mainly regional and extended vertically in both directions. Leaping-over metastasis was another feature. The deeper invasion by the tumor, the higher frequencies of metastasis development, and vice versa. However, leaping-over metastasis was more likely to occur where tumor invasion was less severe. Owing to the high frequency of lymphnode metastasis in the superior mediastinum and the widely spanned leaping-over metastases, an operative approach by three incisions through right thoracotomy with excision of the whole segment of esophagus and anastomosis at cervical region was recommended, in order to dissect lymphnodes in the cervical, thoracic and abdominal regions and to leave less or no metastatic lymphnodes behind.

The role of the C-terminal domain of I kappa B alpha in protein degradation and stabilization

In the present study, the role of the I kappa B alpha C terminus in NF-kappa B/I kappa B alpha regulation was examined in NIH 3T3 cells engineered to inducibly express wild type or mutated human I kappa B alpha proteins under the control of the tetracycline responsive promoter. Deletion studies demonstrated that the last C-terminal 30 amino acids (amino acids (aa) 288 to aa 317, deleted in I kappa B alpha delta 3), including most of the PEST domain, were dispensable for I kappa B alpha function. However, deletions from aa 261 to 317 or aa 269 to 317 (I kappa B alpha delta 1 and I kappa B alpha delta 2 respectively), lacked the ability to dissociate NF-kappa B/DNA complexes in vitro and were unable to inhibit NF-kappa B dependent transcription. Moreover, I kappa B alpha delta 1 and I kappa B alpha delta 2 mutants were resistant to inducer-mediated degradation. Analysis of I kappa B alpha deletions in the presence of protein synthesis inhibitors revealed that, independently of stimulation, I kappa B alpha delta 1 and I kappa B alpha delta 2 had a half-life four times shorter than wild type I kappa B alpha and the interaction of I kappa B alpha delta 1 and I kappa B alpha delta 2 with p65 was dramatically decreased in vivo as measured by co-immunoprecipitation. Interestingly, protease inhibitors which blocked inducer-mediated degradation of I kappa B alpha also stabilized the turnover of I kappa B alpha delta 1 and I kappa B alpha delta 2. Based on these studies, we propose that in the absence of stimulation, the C-terminal domain between aa 269 and 287 may play a role to protect I kappa B alpha from a constitutive protease activity.

Phosphorylation of IkappaBalpha in the C-terminal PEST domain by casein kinase II affects intrinsic protein stability

The NF-kappaB/Rel transcription factors participate in the activation of immune system regulatory genes and viral early genes including the human immunodeficiency virus type 1 long terminal repeat. NF-kappaB/Rel proteins are coupled to inhibitory molecules, collectively termed IkappaB, which are responsible for cytoplasmic retention of NF-kappaB. Cell activation leads to the phosphorylation and degradation of IkappaBalpha, permitting NG-kappaB/Rel translocation to the nucleus and target gene activation. To further characterize the signaling events that contribute to IkappaBalpha phosphorylation, a kinase activity was isolated from Jurkat T cells that specifically interacted with IkappaBalpha in an affinity chromatography step and phosphorylated IkappaBalpha with high specificity in vitro. By using an in-gel kinase assay with recombinant IkappaBalpha as substrate, two forms of the kinase (43 and 38 kDa) were identified. Biochemical criteria and immunological cross-reactivity identified the kinase activity as the alpha catalytic subunit of casein kinase II (CKII). Deletion mutants of IkappaBalpha delta1 to delta4) localized phosphorylation to the C-terminal PEST domain of IkappaBalpha. Point mutation of residues T-291, S-283, and T-299 dramatically reduced phosphorylation of IkappaBalpha by the kinase in vitro. NIH-3T3 cells that stably expressed wild-type IkappaBalpha (wtIkappaB), double-point-mutated IkappaBalpha (T291A, S283A), or triple-point-mutated IkappaBalpha (T291A, S283A, T299A) under the control of the tetracycline-responsive promoter were generated. Constitutive phosphorylation of the triple point mutant was eliminated in vivo, although tumor necrosis factor-inducible IkappaBalpha degradation was unaffected. In cell lines and in transiently transfected cells, mutation of the CKII sites in IkappaBalpha resulted in a protein with increased intrinsic stability. Together with results demonstrating a role for N-terminal sites in inducer-mediated phosphorylation and degradation of IkappaBalpha, these studies indicate that CKII sites in the C-terminal PEST domain are important for constitutive phosphorylation and intrinsic stability of IkappaBalpha.

Virus and host factors are both important determinants of response to interferon treatment among patients with chronic hepatitis C

Virus and host factors have both been linked to the response to interferon treatment among patients with chronic hepatitis C but their relative importance and potential interactions are unclear. Hepatitis C virus genotype and level of viraemia were determined in pretreatment sera from 65 Australian patients treated with interferon-alpha 2b (IFN-alpha 2b), 3 MU tiw for 6 months. Hepatitis C viraemia was quantitated by a competitive reverse transcription-polymerase chain reaction (RT-PCR) method and genotype was determined by a line probe assay. By univariate analysis, there were positive associations between initial (short-term) responses to IFN treatment and younger age (P = 0.004), absence of cirrhosis (P = 0.01), and injecting drug use as risk factor for infection (P = 0.05) but not gender, duration of infection, or level of viraemia. Genotype appeared to be important (P = 0.06) but failed to reach statistical significance. By multivariate analysis, absence of cirrhosis was the only significant independent predictor of treatment response (P = 0.01). Among initial responders, the factors associated with long-term response were the pretreatment HCV RNA titre and the duration of infection. There was a close association between viral genotype, but not viral load, and the severity of liver disease. An interplay of factors determines the outcome of a 6-month course of interferon treatment for hepatitis C. Severity of liver disease, but not the viral load, is the most crucial determinant of initial response to interferon, and histological severity appeared to be influenced by the viral genotype. The level of hepatitis C virus (HCV) viraemia and the duration of infection are independent determinants of long-term response by affecting the relapse rate after interferon treatment.

Biology and treatment of adult acute lymphoblastic leukemia

The molecular analysis of acute lymphoblastic leukemia (ALL) has provided exciting insights into the pathogenesis of this disease. This disease is heterogenous and can be subtyped based on chromosomal, immunophenotypic, and structural criteria. The varying prognostic implications of different ALL subtypes markedly influence the treatment decisions in adults. Many patients with T-cell ALL can be cured with chemotherapy alone. In contrast, patients with early B-lineage ALL with certain chromosomal abnormalities, especially the Philadelphia chromosome, do not have durable responses to chemotherapy and should receive a bone marrow transplantation if an HLA-matched donor is available. Recent reports have shown improved results for adults with B-cell ALL (Burkitt's) after intensive alternating cycles of chemotherapy containing high doses of methotrexate and cyclophosphamide. Future clinical and laboratory investigation should lead to the development of novel and possibly more effective treatments specifically tailored for different subsets of ALL.

Present status of the use of cytokines as adjuvants with vaccines to protect against infectious diseases

Vaccine adjuvants are expected to play an important role in enhancing the immunogenicity of existing and new-generation vaccines against infectious diseases. In particular, adjuvants should direct the immune response in the most appropriate manner--furthering, for example, an expanded B-cell response, a cytotoxic T-cell response, or a T-helper 1 or 2 subset response. While some noncytokine adjuvants have exerted potent effects, their modes of action are most likely mediated by cytokines. Several cytokines have already been shown to be efficient adjuvants in animal models and/or in clinical trials. The mechanisms of cytokine function must be better understood and the techniques for the use of cytokines improved if the full potential of these substances as vaccine adjuvants is to be realized. When used to best advantage, such adjuvants enhance the immunity induced by viral, bacterial, and parasitic vaccines and thereby promote efficient protection or even cure.

pop-1 encodes an HMG box protein required for the specification of a mesoderm precursor in early C. elegans embryos

In C. elegans embryogenesis, the MS blastomere produces predominantly mesodermal cell types, while its sister E generates only endodermal tissue. We show that a maternal gene, pop-1, is essential for the specification of MS fate and that a mutation in pop-1 results in MS adopting an E fate. Previous studies have shown that the maternal gene skn-1 is required for both MS and E development and that skn-1 encodes a transcription factor. We show here that the pop-1 gene encodes a protein with an HMG box similar to the HMG boxes in the vertebrate lymphoid-specific transcriptional regulators TCF-1 and LEF-1. We propose that POP-1 and SKN-1 function together in the early embryo to allow MS-specific differentiation.

Interferon alfa-2b for chronic hepatitis C: effects of dose increment and duration of treatment on response rates. Results of the first multicentre Australian trial. Australia Hepatitis C Study Group

Two hundred and thirty patients with histologically proven chronic hepatitis C were randomized to receive one of the following treatment protocols: (a) 3 million units of interferon alfa-2b thrice weekly for 6 months, (b) 5 million units thrice weekly for 6 months, or (c) 3 million units thrice weekly for 2 years. The short-term response to treatment was defined by normal alanine aminotransferase for at least 3 months and until the end of treatment, and was confirmed by loss of hepatitis C viraemia in 42 (91%) of 46 cases as determined by reverse transcription-polymerase chain reaction. Short-term response to interferon alfa-2b was independent of the incremental dose, being 64% for 5 million units and 58% for 3 million units. Long-term response to interferon alfa-2b was defined by continued normality of alanine aminotransferase levels for at least 6 months after treatment withdrawal. The long-term response rates among responders treated for 6 months and those treated for 2 years were 29% and 54%, respectively (p < 0.001). Among all 18 patients tested, serum HCV-RNA was negative at both 6 and 12 months of follow-up in all long-term responders, and none have subsequently relapsed. Improvement in hepatic necroinflammatory changes was confirmed by quantitative histology (Scheuer score) in responders at the end of interferon alfa-2b treatment. The changes were significantly greater among those who had been treated for 2 years compared with those treated for 6 months (p < 0.05 and p < 0.02, respectively, for portal and lobular inflammation scores). Several pretreatment characteristics could be correlated with a favourable response to interferon alfa-2b. Thus, absence of cirrhosis was associated with a short-term response of 75%, while only 42% of patients with cirrhosis had a short-term response (p < 0.001). The frequency of short-term response to interferon alfa-2b also differed according to mode of disease acquisition, being best for injecting drug use (71%), less favourable for blood transfusion (56%) and worst for sporadic cases (43%) (p < 0.01). This observed difference, however, was not independent of histology on multivariate analysis. In summary, a 5 million unit dose of interferon alfa-2b failed to improve the short-term or long-term response to interferon alfa-2b treatment, but prolongation of interferon alfa-2b treatment to 2 years resulted in substantially improved long-term response rate.

Antipyrine clearance and response to interferon treatment in patients with chronic active hepatitis C

To determine whether hepatic metabolic function affects the response to interferon treatment, we measured antipyrine clearance (APC) in 85 patients with chronic active hepatitis C and compared the results with treatment outcome. Among 55 patients who responded to interferon by normalization of alanine transaminase (ALT), median APC before treatment was 0.47 (range, 0.12 to 0.98; normal range, 0.34 to 1.02 mL/min/kg body wt), a value that was significantly greater than in 30 nonresponders (0.23; 0.08 to 0.67 mL/min/kg body wt, P < .001). APC was closely associated with response to interferon. The response rate among cases with values > 0.25 mL/min/kg body weight was 79%, the same as in cases without cirrhosis. Cases without cirrhosis and with APC of > 0.25 mL/min/kg body weight had an 85% chance of responding to interferon; this was unlikely a simple reflection of histological activity, because the correlation with Scheuer score was poor in this subgroup (r = -.31, P < .05). A second, independent group of 43 patients was used to test the predictive value of APC (using 0.25 mL/min/kg body wt as a cut-off) for response to interferon treatment. In this group, APC correctly predicted positive response to interferon in 75% of cases. APC was also used to measure the effects of treatment on hepatic metabolic function. Regardless of outcome, there was no change in APC at the end of a 6-month course of interferon treatment. Six months later, however, improvement in APC (14%; P < .05) was evident among responders but not in those who had failed to respond to interferon.(ABSTRACT TRUNCATED AT 250 WORDS)

Leucine-responsive regulatory protein: a global regulator of gene expression in E. coli

The leucine-responsive regulatory protein (Lrp) regulates transcription of the many genes of the Lrp regulon, repressing some and activating others, some in response to L-leucine and some independent of it. The physiology and molecular biology of the regulon in Escherichia coli are summarized here. However, the high degree of conservation of the protein suggests that it has an important role in all enterobacteria. We suggest that this role is not only as a transcriptional regulator but also as a determinant of chromosome structure.

Regulation of human immunodeficiency virus type 1 and cytokine gene expression in myeloid cells by NF-kappa B/Rel transcription factors

CD4+ macrophages in tissues such as lung, skin, and lymph nodes, promyelocytic cells in bone marrow, and peripheral blood monocytes serve as important targets and reservoirs for human immunodeficiency virus type 1 (HIV-1) replication. HIV-1-infected myeloid cells are often diminished in their ability to participate in chemotaxis, phagocytosis, and intracellular killing. HIV-1 infection of myeloid cells can lead to the expression of surface receptors associated with cellular activation and/or differentiation that increase the responsiveness of these cells to cytokines secreted by neighboring cells as well as to bacteria or other pathogens. Enhancement of HIV-1 replication is related in part to increased DNA-binding activity of cellular transcription factors such as NF-kappa B. NF-kappa B binds to the HIV-1 enhancer region of the long terminal repeat and contributes to the inducibility of HIV-1 gene expression in response to multiple activating agents. Phosphorylation and degradation of the cytoplasmic inhibitor I kappa B alpha are crucial regulatory events in the activation of NF-kappa B DNA-binding activity. Both N- and C-terminal residues of I kappa B alpha are required for inducer-mediated degradation. Chronic HIV-1 infection of myeloid cells leads to constitutive NF-kappa B DNA-binding activity and provides an intranuclear environment capable of perpetuating HIV-1 replication. Increased intracellular stores of latent NF-kappa B may also result in rapid inducibility of NF-kappa B-dependent cytokine gene expression. In response to secondary pathogenic infections or antigenic challenge, cytokine gene expression is rapidly induced, enhanced, and sustained over prolonged periods in HIV-1-infected myeloid cells compared with uninfected cells. Elevated levels of several inflammatory cytokines have been detected in the sera of HIV-1-infected individuals. Secretion of myeloid cell-derived cytokines may both increase virus production and contribute to AIDS-associated disorders.

Transcription factor IRF-2 exerts its oncogenic phenotype through the DNA binding/transcription repression domain

The Interferon Regulatory Factors-1 and -2 (IRF-1 and IRF-2) play a transcriptional role in the regulation of the IFN-beta gene as well as other immunoregulatory genes. IRF-1 serves as a transcriptional activator whereas IRF-2 acts as an antagonistic transcriptional repressor. IRF-1 and IRF-2 also play opposing functional roles in cell growth regulation, and are implicated as a potential antioncogene and oncogene, respectively. To analyse the relationship between DNA binding/transcriptional repression and oncogenic transformation, NIH3T3 cells expressing C-terminal deletions of IRF-2 were established and assayed for transformation by saturation density analysis, anchorage independent growth in soft agar and tumor formation in nude mice. Cells expressing an IRF-2 protein of at least 160 N-terminal amino acids were transformed in vitro and tumorigenic in vivo, thus mapping IRF-2 oncogenic activity to its DNA binding/transcriptional repression domain. Overexpression of wild-type and truncated IRF-2 proteins resulted in reduced IFN-beta mRNA levels following induction by dsRNA. However, there was no effect of IRF-2 on IFN-beta inducibility by Sendai virus infection, suggesting the involvement of multiple IFN-beta induction pathways. In DNA binding assays, recombinant IRF-2 was found to preferentially bind to the IFN-beta PRDI site compared to IRF-1. These studies indicate that the transformed phenotype resulting from overexpression of IRF-2 may be due to constitutive engagement of the IRF-E recognition site, thus preventing DNA binding and transactivation of putative tumor suppressor genes by the IRF-1 anti-oncogene.

Retrovirus-mediated transfer of nuclear factor-kappa B subunit genes modulates I kappa B alpha and interferon beta expression

Nuclear factor (NF)-kappa B proteins regulate the transcription of numerous genes involved in the immune response, transcription control, and viral pathogenesis. To examine the effect of ectopic expression of NF-kappa B proteins on DNA-binding activity and gene expression, individual NF-kappa B subunit genes were introduced into NIH 3T3 cells via retrovirus-mediated gene transfer. Expression of NF-kappa B subunits RelA (p65), NF-kappa B1 (p105), NF-kappa B2 (p100), and c-Rel increased the basal level of nuclear NF-kappa B DNA binding in NIH 3T3 cells, whereas expression of delta RelA (p65 delta) and NF-kappa B2 (p52) subunits did not affect basal level activity. Tumor necrosis factor-alpha treatment of the NF-kappa B-expressing cells stimulated the induced level of DNA-binding activity, reflecting interaction between endogenous murine and transfected human NF-kappa B proteins. Interestingly, expression of RelA (p65), c-Rel, NF-kappa B1 (p105), NF-kappa B2 (p100), and NF-kappa B2 (p52) subunits increased I kappa B alpha protein levels from 3- to 30-fold, indicating that one mechanism to compensate for the increased expression of NF-kappa B proto-oncogenes was to increase the synthesis and/or stability of the regulatory I kappa B alpha protein. In addition, overexpression of RelA (p65), c-Rel, NF-kappa B2 (p100), and NF-kappa B2 (p52) altered the induction kinetics of IFN-beta mRNA after Sendai virus infection, whereas overexpression of NF-kappa B1 (p105) dramatically decreased IFN-beta mRNA induction.

Differential transcriptional activation in vitro by NF-kappa B/Rel proteins

Distinct NF-kappa B subunit combinations contribute to the specificity of NF-kappa B-mediated transcriptional activation and to the induction of multiple cytokine genes including interferon-beta (IFN-beta). To evaluate the regulatory influence of different homo- and heterodimers, NF-kappa B subunits were analyzed for transcriptional activity in vitro using test templates containing two types of NF-kappa B recognition elements (the human immunodeficiency virus type 1 enhancer and the IFN-beta-positive regulatory domain-II (PRDII) as well as IFN-beta PRDIII-PRDI-PRDII linked to the -56 minimal promoter of rabbit beta-globin. Recombinant NF-kappa B subunits (p50, p65, c-Rel, p52, and I kappa B alpha) and interferon regulatory factor 1 were produced from either Escherichia coli or baculovirus expression systems. Transcriptional analysis in vitro demonstrated that 1) various dimeric complexes of NF-kappa B differentially stimulated transcription through the human immunodeficiency virus enhancer or PRDII up to 20-fold; 2) recombinant I kappa B alpha specifically inhibited NF-kappa B-dependent transcription in vitro; and 3) different NF-kappa B complexes and interferon regulatory factor 1 cooperated to stimulate transcription in vitro through the PRDIII-PRDI-PRDII virus-inducible regulatory domains of the IFN-beta promoter. These results demonstrate the role of NF-kappa B protein dimerization in differential transcriptional activation in vitro and emphasize the role of cooperativity between transcription factor families as an additional regulatory level to maintain transcriptional specificity.

Subcellular redistribution of HTLV-1 Tax protein by NF-kappa B/Rel transcription factors

The viral oncogene Tax derived from human T cell leukemia virus type I (HTLV-I) is a positive transcriptional activator of HTLV-1 gene expression. Tax is also able to indirectly stimulate transcription of several growth regulatory genes by an indirect mechanism via association with host transcription factors. One of the cellular targets of the trans-activating effects of Tax is the NF-kappa B/Rel family transcription factors, pleiotropic regulators of immunoregulatory, cytokine, and viral gene expression. Recent studies demonstrated that specific subunits of NF-kappa B (NFKB2(p 100) and c-Rel) were overexpressed in HTLV-I-infected and Tax-expressing cells. Furthermore, Tax physically associated with NFKB2(p 100). Monospecific antibodies directed against individual NF-kappa B subunits were generated and used to investigate the consequences of the interactions between Tax and NF-kappa B in a cotransfection-immunofluorescence assay. These studies demonstrate: (1) distinct compartmentalization of NF-kappa B precursors and products, (2) differential induction of the endogenous I kappa B alpha protein by transfected NF-kappa B subunits, (3) subcellular relocalization of Tax to the cytoplasm or nucleus depending on the coexpressed NF-kappa B subunit, and (4) Tax interaction with the Rel homology domain region of NFKB2. These studies indicate that the transcription modulatory influence of HTLV-I Tax may be significantly influenced by cytoplasmic-nuclear partitioning associated with the NF-kappa B proteins.

Demonstration of differences in vascular permeability in experimental tumors by use of 19F magnetic resonance imaging

RATIONALE AND OBJECTIVES

In vivo assessment of tumor vascular permeability may provide useful information for chemotherapy treatment planning or for the assessment of treatment effectiveness. We aimed to assess vascular permeability in two tumor sublines as well as changes in vascular permeability with tumor growth by using 19F magnetic resonance imaging.

METHODS

An emulsion of perfluorotributylamine was used as a tumor extravascular contrast agent for 19F MRI. The amount of emulsion that leaked into tumor interstitial space was analyzed qualitatively with imaging. A quantitative study of vascular permeability was done with a separate group of tumors by use of Evans blue dye.

RESULTS

One tumor type was more permeable to both perfluorotributylamine emulsion and Evans blue than was the second tumor type. The difference was attributed to a difference in surface area for exchange. In larger tumors of both types, pooling of large amounts of perfluorocarbon occurred and was assumed to be attributable to hemorrhage or blood flow stasis or both.

CONCLUSION

19F MRI is capable of demonstrating the permeability of tumor vessels to macromolecular substances.

A Salmonella protein that is required for resistance to antimicrobial peptides and transport of potassium

The ability of invading pathogens to proliferate within host tissues requires the capacity to resist the killing effects of a wide variety of host defense molecules. sap mutants of the facultative intracellular parasite Salmonella typhimurium exhibit hypersensitivity to antimicrobial peptides, cannot survive within macrophages in vitro and are attenuated for mouse virulence in vivo. We conducted a molecular genetic analysis of the sapG locus and showed that it encodes a product that is 99% identical to the NAD+ binding protein TrkA, a component of a low-affinity K+ uptake system in Escherichia coli. SapG exhibits similarity with other E. coli proteins implicated in K+ transport including KefC, a glutathione-regulated efflux protein, and Kch, a putative transporter similar to eukaryotic K+ channel proteins, sapG mutants were killed by the antimicrobial peptide protamine in the presence of both high and low K+, indicating that protamine hypersensitivity is not due to K+ starvation. Strains with mutations in sapG and either sapJ or the sapABCDF operon were as susceptible as sapG single mutants, suggesting that the proteins encoded by these loci participate in the same resistance pathway. SapG may modulate the activities of SapABCDF and SapJ to mediate the transport of peptides and potassium.

Viral induction of the human beta interferon promoter: modulation of transcription by NF-kappa B/rel proteins and interferon regulatory factors

Multiple regulatory domains within the -100 region of the beta interferon (IFN-beta) promoter control the inducible response of the IFN gene to virus infection. In this study, we demonstrate that the formation of NF-kappa B-specific complexes on the positive regulatory domain II (PRDII) precedes the onset of detectable IFN-beta transcription in Sendai virus-infected cells. By using NF-kappa B subunit-specific antibodies, a temporal shift in the composition of NF-kappa B subunits in association with the PRDII domain is detected as a function of time after virus infection. Furthermore, a virus-induced degradation of I kappa B alpha (MAD3) protein is observed between 2 and 8 h after infection; at later times, de novo synthesis of I kappa B alpha restores I kappa B alpha to levels found in uninduced cells and correlates with the down regulation of IFN-beta transcription. In cotransfection experiments using various NF-kappa B subunit expression plasmids and two copies of PRDII/NF-kappa B linked to a chloramphenicol acetyltransferase reporter gene, we demonstrate that expression of p65, c-Rel, or p50 or combinations of p50-p65 and p65-c-Rel differentially stimulated PRDII-dependent transcription. Coexpression of I kappa B alpha completely abrogated p65-, c-Rel-, or p65-p50-induced gene activity. When the entire IFN-beta promoter (-281 to +19) was used in coexpression studies, synergistic stimulation of IFN-beta promoter activity was obtained when NF-kappa B subunits were coexpressed together with the IFN regulatory factor 1 (IRF-1) transcription factor. Overexpression of either I kappa B or the IRF-2 repressor was able to abrogate inducibility of the IFN-beta promoter. Thus, multiple regulatory events--including differential activation of DNA-binding NF-kappa B heterodimers, degradation of I kappa B alpha, synergistic interaction between IRF-1 and NF-kappa B, and decreased repression by I kappa B and IRF-2--are all required for the transcriptional activation of the IFN-beta promoter.

Mutational analysis of interferon (IFN) regulatory factors 1 and 2. Effects on the induction of IFN-beta gene expression

Interferon (IFN) regulatory factor 1 (IRF-1) and IRF-2 are structurally similar but functionally distinct transcription factors that bind to the positive regulatory domains I and III (PRDI/III) within the human IFN-beta promoter. To begin structure-function analysis of IRF-1 and IRF-2, the regulatory potential of carboxyl-terminal deletion mutants was analyzed by co-transfection studies in human cells and was correlated with DNA binding capacity. Transcriptional repression by IRF-2 was contained within the first 125 amino-terminal amino acids and correlated directly with IRF-2 DNA binding; deletion to a protein of 100 amino acids resulted in loss of repression and IRF-2 DNA binding. Thus, the carboxyl terminus appears dispensible for trans-repression. Hybrid constructs which fuse the DNA binding domain of IRF-1 and IRF-2 to the trans-activation domain of NF-kappa B p65 were also generated; both IRF-1/p65 and IRF-2/p65 chimeras were strong transcriptional activators. IRF-2-mediated repression was also dominant over trans-activation by these fusion proteins. The trans-activation region of IRF-1 resides in the carboxyl terminus, primarily carboxyl-terminal to amino acid 250. Mutation of three potential casein kinase II phosphorylation sites within the IRF carboxyl terminus failed to identify an essential site that contributes to IRF-1 trans-activation potential.

Comparative efficacy of topical ciprofloxacin for treating Mycobacterium fortuitum and Mycobacterium chelonae keratitis in an animal model

Mycobacterium fortuitum and M. chelonae are the two most common causes of nontuberculous mycobacterial keratitis, and they may be difficult to differentiate at diagnosis. Mycobacterium fortuitum is generally more sensitive to ciprofloxacin in vitro than is M. chelonae. Using a rabbit model, we compared the efficacy of topical ciprofloxacin (3 mg/ml) against M. chelonae keratitis to its efficacy against M. fortuitum keratitis. After four days of therapy, ciprofloxacin significantly reduced the number of both organisms in treated eyes compared to untreated control eyes (both P values < .001). Mean culture ratios (colony-forming units in treated eye divided by colony-forming units in untreated eye for each rabbit) were used to compare efficacy between groups. When all treated animals were considered, no significant difference was found between groups (P = .13). When outlier values were excluded, ciprofloxacin was more effective against M. fortuitum than M. chelonae (P = .01). When treated and untreated eyes were compared after therapy in the M. fortuitum group, ciprofloxacin treatment was associated with a reduction in mean stromal infiltrate area (P = .03) and in the tendency to form satellite lesions (P = .07). A clinical effect was not observed in the M. chelonae group. Although ciprofloxacin is effective against both organisms, it appears to be less effective against M. chelonae than M. fortuitum in vivo.

Thioallyl compounds: potent inhibitors of cell proliferation

S-Allylmercaptocysteine was shown to inhibit vascular smooth-muscle and umbilical endothelial cell proliferation. Inhibition was dose-dependent and affected smooth-muscle cells more than endothelial cells. S-Allylmercaptocysteine was two orders of magnitude more potent than S-allylcysteine and cells grown in its presence showed distinct changes in their phosphorylation compared to untreated controls. Among the proteins whose phosphorylation was altered were GTP-activating protein, protein tyrosine phosphatase-1B and p34cdc2. We conclude that thioallyl compounds, natural constituents of garlic and known to inhibit malignant cells, can also reduce the proliferation of normal cells.

Potential role of granulocyte-macrophage colony-stimulating factor as vaccine adjuvant

The uses of GM-CSF as an immunomodulator and vaccine adjuvant are reviewed. GM-CSF has a variety of effects on immune responses: it induces class II major histocompatibility complex antigen expression on the surface of macrophages; it enhances dendritic cell maturation and migration; it results in a localized inflammation at the injection site; and it has marked effects on maturation of haematopoietic progenitor cells in the bone marrow. Animal and human studies suggest that administration of GM-CSF can increase antibody titres to foreign antigens. Monkeys injected with human interleukin (IL)-3 plus GM-CSF, at a different injection site, developed peak antibody titres which were 8- to 30-fold higher than those in monkeys injected with IL-3 alone. In a study of ovarian cancer patients receiving GM-CSF to prevent chemotherapy-induced neutropenia, two patients who had demonstrated a low titre of antithyroid antibodies prior to the study showed an increase in antibody titre and transient thyroiditis after administration of GM-CSF. Recently a GM-CSF/antigen fusion protein has been tested. An antibody corresponding to a specific idiotype expressed on B-cell lymphomas was fused to GM-CSF and injected into mice with B-cell lymphoma xenografts. The mice developed antibodies to the lymphoma and there was a protective effect against disease progression. Preliminary results of clinical trials using GM-CSF in humans suggest that it enhances antibody responses to hepatitis B vaccine. On the basis of these preliminary results, several clinical trials are being planned and it would appear that GM-CSF has potential as a vaccine adjuvant.

Comparison of topical antibiotics for treating Mycobacterium fortuitum keratitis in an animal model

The efficacy of three topical antibiotic treatments for Mycobacterium fortuitum (strain ATCC-6841) keratitis were compared in rabbits. Rabbits were treated with ciprofloxacin (3 mg/ml) or clarithromycin (20 mg/ml) or a combination of amikacin (100 mg/ml) and vancomycin (50 mg/ml). All three treatments significantly reduced the number of organisms in treated eyes compared to untreated, control eyes (all P values < .001). No significant difference in treatment efficacy was found between the three treatment groups (all P values > or = .48), although ciprofloxacin (3 mg/ml) was more effective than clarithromycin (20 mg/ml) after excluding outliers (P = .01). All treatments stabilized or reduced the size of stromal infiltrates after four days of therapy, whereas infiltrates continued to enlarge in untreated eyes. These results suggest that topical clarithromycin, topical ciprofloxacin, and combined amikacin and vancomycin may all be clinically useful for treating M. fortuitum keratitis. Both clarithromycin and ciprofloxacin were better tolerated than combined amikacin and vancomycin. This study supports the further development of clarithromycin, a new macrolide antibiotic, as a topical drug for treatment of M. fortuitum keratitis.

A new approach to input device key design using fingerprints

A new approach to designing input device keys is proposed, and a TV remote controller is used as an example to demonstrate the new approach for studying the relationship between fingerprints and key geometry. One hundred subjects' fingerprints of thumbs and index fingers of both hands were collected, and a computer program was used for converting the fingerprint to a bitmap form. Subsequently, the data were analysed to provide some guidelines for determining the key size and key shape for the input device. Finally, the fingerprints were used to study the pattern of finger press and the justification for keycap curvature for finger placement. The results showed that the new approach can be useful in guiding designers of input device keys. A further benefit of this study is in providing a more systematic approach with considerable general potential for studying input device keys.

Measurement of vascular volume in experimental rat tumors by 19F magnetic resonance imaging

RATIONALE AND OBJECTIVES

In-vivo assessment of tumor vascular volume may provide useful information for treatment planning or the assessment of treatment effectiveness. The goals of our study were to measure percent vascular volume in two experimental tumor sublines using 19F magnetic resonance imaging (MRI) and to assess changes in tumor blood volume with growth.

METHODS

An emulsion of perfluorotributylamine (FTBA) was used as a vascular contrast agent for 19F MRI: The amount of emulsion in the tumor vasculature was measured by 19F MRI and used to calculate percent vascular volume. A separate ex-vivo study of vascular volume was conducted using the dye Hoechst 33342. A total of five rats were studied by MRI and 14 by the ex-vivo method.

RESULTS

The ranges of percent vascular volume values measured in the imaging and Hoechst dye studies were 2% to 9% and 1.25 to 7%, respectively. A trend toward decreasing percent vascular volume with increasing tumor volume was evident in one tumor subline.

CONCLUSIONS

The quantitative 19F MRI technique was effective for measuring percent vascular volume and changes in vascular volume with growth.

Alpha-interferon 2b in the treatment of chronic hepatitis C: interim report of the first multicentre Australian trial

Interferon has been shown to be effective in the treatment of chronic hepatitis C but the optimal treatment regime has not yet been defined. Studies using 3 million units (MU) of interferon thrice weekly (tiw) for 6 months have shown normalization of serum alanine aminotransferase (ALT) in about 50% of patients, but relapse occurs in at least 50% of responders after interferon is stopped. The aims of this study were to determine whether 5 MU of interferon tiw produces a higher response rate than 3 MU tiw and to examine if the higher dose results in more sustained remissions. In addition, factors that are associated with a more or less favourable response to interferon treatment were sought. Overall, 65% of patients responded and no advantage of the higher dose therapy was found, either in terms of response or relapse rate after treatment. The presence of cirrhosis on the pre-treatment liver biopsy was associated with a poor response rate to interferon and a trend towards a higher relapse rate. Risk factor for acquisition of disease was also related to likelihood of response but not relapse. We conclude that two thirds of Australian patients with chronic hepatitis C initially respond to interferon treatment. Positive predictors of response are intravenous drug use as a risk factor and histologically less severe liver disease. Relapse occurs in two thirds of all responders.

Molecular, functional, and evolutionary analysis of sequences specific to Salmonella

In that salmonellae have been implicated in an unprecedented array of diseases, sequences found to be specific to this species are often thought to be involved in the virulence attributes not seen in other enteric bacteria. To identify the molecular, genetic, and phenotypic characteristics that differentiate bacterial species, we analyzed five cloned DNA fragments that were originally described as being confined to Salmonella. Most of these segments mapped to unique positions on the Salmonella typhimurium chromosome indicative of independent evolutionary events, and three had G+C contents considerably lower than that of the Salmonella genome, suggesting that they arose through horizontal transfer. The nucleotide sequence was determined for one of the clones exhibiting an atypical base composition. This 4.9-kb fragment contained an open reading frame with structural similarity to the LysR family of transcriptional regulators. Strains harboring deletions in this region were tested for > 120 phenotypic characteristics including the effects on a collection of environmentally regulated lac gene fusions. In addition, all deletion strains behaved like the wild-type parent when tested for virulence in mice.

A comparison of single nucleotide primer extension with mispairing PCR-RFLP in detecting a point mutation

A recent report by Petruzzella et al. (BBRC 186, 491-497, 1992) raised a question as to whether a point mutation in the mitochondrial ND2 gene (BBRC 182, 238-246, 1992) is relevant to Alzheimer's disease. The argument was based on their inability to detect the point mutation at position 5460 in codon 331 in the DNAs extracted from 15 patients with Alzheimer's disease using mispairing PCR-RFLP. To clarify the discrepancy, we tested the DNAs reported by Petruzzella et al. for the mutation by single-nucleotide primer extension. The present work confirms our previous report and extends our finding of the point mutation in 8 of the 15 AD DNAs.

Hepatitis C as the cause of chronic non-A, non-B hepatitis: high sensitivity of simultaneous measurement of core and non-structural antibodies

First generation serologic tests (ELISA-1) for hepatitis C virus infection measure antibodies directed against a short non-structural segment of the virus (anti-c100-3). A major disadvantage of this test is that it lacks sensitivity in the identification of hepatitis C virus among patients at risk of infection. Thus, only 70-90% of chronic non-A, non-B cases are ELISA-1 positive. The present study set out to determine whether antibodies directed against the core region would be a more sensitive indicator of hepatitis C virus infection in patients with chronic non-A, non-B hepatitis. Sera were studied from 97 patients with raised serum alanine aminotransferase levels for more than 6 months in whom other causes of abnormal alanine aminotransferase were excluded. Using ELISA-1, 85 sera (87%) were anti-c100-3 positive. Sera were then tested for presence of antibody directed against Po, a core peptide of a Japanese strain of hepatitis C virus, using an ELISA method. Eighty-eight sera (91%) were anti-Po positive. Among the 12 anti-c100-3 negative patients, six were anti-Po positive. A second generation ELISA for anti-HCV (ELISA-2) incorporates a different antibody to the core region (c22-3) in addition to an expanded non-structural region, c200, which consists of c100-3 plus c33c. With these tests, all sera but one were positive, including 11 of 12 ELISA-1 negative and eight of nine anti-Po negative sera.(ABSTRACT TRUNCATED AT 250 WORDS)

Highly acetylated H4 is associated with histone displacement in rat spermatids

The presence of highly acetylated histone H4 during spermatogenesis was studied to evaluate its correlation with the events of gene transcription, histone deposition, and histone displacement. We utilized an antibody raised to a pentaacetylated synthetic peptide that preferentially recognizes highly (tetra- and tri-) acetylated forms of rat testis H4. Electrophoretic separation of histones from enriched fractions of spermatogenic cells followed by detection of these forms by staining and by immunoblotting using this antibody showed that the highly acetylated forms were limited almost exclusively to spermatids beginning at step 11 of development. Immunoflurescence also revealed a striking polarity in the progression of histone from the spermatid nucleus. Highly acetylated H4 was displaced from the anterior to the caudal portion of the spermatid nucleus during steps 11 and 12, along with other histones, prior to their displacement by transition proteins. Thus, while monoacetylated and low levels of diacetylated forms of H4 were associated with stages at which histone deposition and transcription occur, the more highly acetylated forms appeared in high levels only at the stage at which histone displacement occurs.

The lrp gene product regulates expression of lysU in Escherichia coli K-12

In Escherichia coli K-12, expression of the lysU gene is regulated by the lrp gene product, as indicated by an increase in the level of lysyl-tRNA synthetase activity and LysU protein in an lrp mutant. Comparison of the patterns of protein expression visualized by two-dimensional gel electrophoresis indicated that LysU is present at higher levels in an lrp strain than in its isogenic lrp+ parent. The purified lrp gene product was shown to bind to sites upstream of the lysU gene and to protect several sites against DNase I digestion. A region extending over 100 nucleotides, between 60 and 160 nucleotides upstream from the start of the lysU coding sequence, showed altered sensitivity to DNase I digestion in the presence of the Lrp protein. The extent of protected DNA suggests a complex interaction of Lrp protein and upstream lysU DNA.

Lambda placMu insertions in genes of the leucine regulon: extension of the regulon to genes not regulated by leucine

The leucine regulon coordinates the expression of several Escherichia coli genes according to the presence of exogenous leucine, which interacts with the lrp gene product, Lrp. We isolated and characterized 22 strains with lambda placMu insertions in Lrp-regulated genes. Lrp and leucine influenced gene expression in a surprising variety of ways. We identified two genes that are regulated by Lrp and not affected by L-leucine. We therefore rename this the leucine-lrp regulon. Genes coding for glycine cleavage and leucine biosynthesis enzymes have been identified as members of the leucine-lrp regulon. We suggest that the lrp gene product activates genes needed for growth in minimal medium, and we show that the gene is repressed by its own product and is highly repressed during growth in rich medium.

Detection of point mutations in codon 331 of mitochondrial NADH dehydrogenase subunit 2 in alzheimer's brains

Point mutations in codon 331 of mitochondrial NADH dehydrogenase subunit 2 (ND2) were detected in 10 of 19 Alzheimer's brains but not in 11 normal brains. The same mutations were also detected in 2 of 6 patients with amyotrophic lateral sclerosis (ALS). However, neurofibrillary tangles and neuritic plaques characteristic of Alzheimer's disease were found histologically in the brain of one ALS patient who was positive of the mutation. The finding suggests that a point mutation in ND2 is a potential risk factor for Alzheimer's disease.