Characterization of DBT cell clones derived from cells persistently infected with the JHM strain of mouse hepatitis virus

Twelve clones derived from the cells persistently infected with the JHM strain (JHMV) of mouse hepatitis virus (MHV) were established from mouse astrocytoma-derived DBT cells and characterized. All the cell clones were resistant to superinfection with MHV. Only one of the persistently infected cell clone synthesized viral RNA and proteins and produced virus particles. Viral RNA was detectable in some other cell clones without production of viral protein nor the virus. No cell clones exhibited contact fusion activity. The results suggested that such variety of cell clones might have resulted from persistent infection with JHMV.

Effects of selective phosphodiesterase type IV inhibitor, rolipram, on signal transducing phospholipases in neutrophil: inhibition of phospholipases A2, D but not C

The effects of a selective phosphodiesterase (PDE) type IV inhibitor, rolipram, on activation of neutrophil phospholipases in response to the chemotactic peptide formyl-methiony-leucyl-phenylalanine (fMLP) were investigated. fMLP caused liberation of arachidonic acid, a precursor of eicosanoids and in the presence of 0.3% butanol, production of phosphatidylbutanol, an indicator of phospholipase D activation. Rolipram inhibited arachidonic acid release and phosphatidylbutanol formation. The inhibition was considered to be mediated through a cAMP-dependent mechanism, probably protein kinase A, because selective inhibitors for protein kinase A, H-8 or H-89 overcame the action of rolipram. The concentration-dependent inhibitory profile for phospholipase D activation was similar to that for lysosomal enzyme release, providing additional evidence for the functional link of these two events. In contrast, rolipram was without effect on fMLP-induced inositol trisphosphate production. These results indicate that this selective PDE IV inhibitor had no effect on phosphatidylinositol-specific phospholipase C activation but effectively prevented activation of phospholipases A2 and D coupled to arachidonic acid liberation and lysosomal enzyme release, respectively.

Selenocysteylation in eukaryotes necessitates the uniquely long aminoacyl acceptor stem of selenocysteine tRNA(Sec)

Selenocysteine synthesis is achieved on a specific tRNA, tRNA(Sec), which is first charged with serine to yield seryl-tRNA(Sec). Eukaryotic tRNA(Sec) exhibits an aminoacyl acceptor stem with a unique length of 9 base pairs. Within this stem, two base pairs, G5a.U67b and U6.U67, drew our attention, whose non-Watson-Crick status is maintained in the course of evolution either through U6.U67 base conservation or base covariation at G5a.U67b. Single or double point mutations were performed, which modified the identity of either or both of the base pairs. Serylation by seryl-tRNA synthetase was unaffected by substitutions at either G5a.U67b or U6.U67. Instead, and quite surprisingly, changing G5a.U67b and U6.U67 to G5a-C67b/U6.G67 or G5a-C67b/C6-G67 gave rise to a tRNA(Sec) mutant exhibiting a gain of function in serylation. This finding sheds light on the negative influence born by a few base pairs in the acceptor stem of tRNA(Sec) on its serylation abilities. The tRNA(Sec) capacities to support selenocysteylation were next examined with regard to a possible role played by the two non-Watson-Crick base pairs and the unique length of the acceptor stem. It first emerges from our study that tRNA(Sec) transcribed in vitro is able to support selenocysteylation. Second, none of the point mutations engineered at G5a.U67b and/or U6.U67 significantly modified the selenocysteylation level. In contrast, reduction of the acceptor stem length to 8 base pairs led tRNA(Sec) to lose its ability to efficiently support selenocysteylation. Thus, our study provides strong evidence that the length of the acceptor stem is of prime importance for the serine to selenocysteine conversion step.

[Prognosis after radical surgery in prostatic cancer patients with lymph nodes metastases]

We investigated prognosis of clinically localized prostatic adenocarcinoma patients who revealed to have had lymph nodes metastases by undergoing radical surgery. Eighty six patients were operated during the last 15 years under the clinical diagnosis of A2, 9 patients, B1, 15 B2, 13 and C, 49, respectively. Total prostatectomy was done to 51, total cystoprostatectomy to 33 and total pelvic excentration to 2 patients. Of these patients, 22.2% with stage A2, 20.2% with B1, 7.7% with B2 and 43.8% with C had positive nodes and the rate of positive nodes in stage C was significantly higher than that in other stages (p < 0.01). Regarding histological differentiation, 15.4% of well, 23.7% of moderate and 51.6% of poor by differentiated had positive nodes and the rate of positive nodes in poor by differentiated was significantly higher (p < 0.01). In 2 of 21 cases whose lymph nodes were dissected to the level of the aortic bifurcation, positive nodes were detected only in the external and common iliac areas. These two cases were missed, i.e., "false negative" if limited nodes dissection was performed. All patients with positive nodes were treated with hormonal therapy. The 5-year cancer specific survival rate of patients with positive (n = 27) and negative (n = 59) nodes were 66.4% and 92.4%, respectively. The prognosis of patients with positive nodes were significantly worse than that of patients with negative nodes (p < 0.001). Among 27 patients with positive nodes, significant prognostic factor was not number or extent of positive nodes, but histological differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of hepatitis C virus replication by antisense oligonucleotide in culture cells

Oligonucleotides complementary to the sequences containing the initiator codon, AUG, of the core region of positive-stranded hepatitis C virus (HCV) were tested for their effects on viral translation in a cell-free protein synthesis system and on viral replication in a human T-lymphotropic virus type I infected cell line, MT-2C, which was cloned by the limited dilution method from MT-2 cells and showed more efficient HCV replication than an uncloned population of MT-2 cells. Treatment of HCV-infected MT-2C cells with the antisense oligonucleotide (10 microM) had a dramatic inhibitory effect on viral replication. This result suggests that the antisense oligonucleotide complementary to the sequence close to the initiation codon of the core region might be useful as an antiviral agent against HCV replication.

Amyotrophic lateral sclerosis with marked neurological asymmetry: clinicopathological study

We attempted to correlate the marked neurological asymmetry observed in two amyotrophic lateral sclerosis patients with their histopathological lesions. Patient 1, a 52-year-old man, developed dysarthria and dysphagia, followed by muscle weakness in the left arm and then of the left leg. Patient 2, a 44-year-old man, developed muscle weakness in the left hand, left leg, tongue with left-sided predominance, right hand and right leg in that order of progression. Both patients exhibited moderate to marked left-sided predominant involvement of the lower motor neuron system, accompanied by retained or hyperactive deep tendon reflexes on the left side in the early stage of their illness. Most of the asymmetry in the lower motor neuron system involvement persisted until the death of the patients. Histopathological examinations, including semiquantitative analysis, revealed that both patients exhibited left-sided predominant degeneration of the lower motor neuron system at those spinal cord levels where the neurological asymmetry was of a moderate to marked degree. In addition left-sided predominant degeneration of the lateral corticospinal tracts was seen in both patients and right-sided predominant involvement of Betz cells in the leg area of the motor cortex of patient 1. This pattern of both the neurological and histopathological asymmetry suggested the probable existence of an intimate somatotopically related linkage between the upper motor neuron system degeneration and lower motor neuron system degeneration in both patients.

Deletion and site-directed mutagenesis of EF-hand domain of phospholipase C-delta 1: effects on its activity

In order to elucidate a role of a putative EF-hand motif (144-172) in phospholipase C-delta 1 (PLC-delta 1), deletion and point mutation of the enzyme were performed and the mutated cDNAs were expressed in CHO cells and E. coli AD202 strain. Deletion of amino acid residues of 141-236 or 173-236 resulted in abolition of PLC activity. However, the decreased PLC activity to 15-20% by deletion of the EF-hand motif (144-172) was still Ca(2+)-dependent. Furthermore, mutants, in which conserved Asp153, Asp157, Glu164 or all these acidic amino acids in the EF-hand motif were replaced with alanine residues, showed nearly the same PLC activity and Ca(2+)-dependency as those of wild-type. These results suggest that the region containing the EF-hand motif may not play a role in regulation of Ca(2+)-sensitivity of PLC-delta 1, but is important for its activity.

Inhibition of viral multiplication in cells chronically infected with mouse hepatitis virus by antisense RNA against the polymerase gene

Recently, we showed that the antisense RNA containing a hammerhead ribozyme sequence against the polymerase gene of mouse hepatitis virus (MHV) inhibited viral multiplication in acute infection [10]. In the present study, we examined the inhibitory effects of an antisense RNA on viral multiplication in chronic MHV infection. In cell line LR-2, in which the 926-nucleotide (nt) antisense RNA containing a ribozyme sequence against the polymerase gene was expressed constitutively at a high level, chronic MHV infection was established through the maintenance of infection over 100 days postinfection (d.p.i.). After 200 d.p.i., no infectious progeny virus was observed in the culture medium of chronically MHV infected LR-2 cells. Our present results showed that the anitsense RNA could also inhibit viral multiplication in chronic MHV infection.

Danazol concentrations in ovary, uterus, and serum and their effect on the hypothalamic-pituitary-ovarian axis during vaginal administration of a danazol suppository

OBJECTIVE

To determine danazol concentrations in the ovary, uterus, and serum during daily vaginal administration of a danazol suppository and to examine its effect on the hypothalamic-pituitary-ovarian axis.

DESIGN

Sampling of tissues after vaginal or oral administration of danazol and sampling of blood during control and danazol-administration menstrual cycles.

SETTING

Outpatient volunteers and inpatients at a public hospital.

PARTICIPANTS

Thirty patients who were to undergo hysterectomy and oophorectomy because of uterine leiomyoma and eight regularly menstruating volunteers.

INTERVENTIONS

Danazol was administered as a vaginal suppository (100 mg) or orally (400 mg).

MAIN OUTCOME MEASURE

Danazol concentrations in the ovary, uterus, and serum, and serum E2 and P levels.

RESULTS

Danazol concentrations in the ovary and uterus after daily vaginal administration of a suppository containing 100 mg danazol were comparable to those after daily oral administration of 400 mg danazol, but the serum danazol concentration was much lower. Menstrual cycle patterns of serum E2 and P levels were normal during daily vaginal administration of a danazol suppository.

CONCLUSION

Daily administration of a suppository containing 100 mg danazol produces high ovarian and uterine concentrations but low serum concentrations, and no effect was detected on the hypothalamic-pituitary-ovarian axis.

Recurrent subarachnoid hemorrhage from untreated ruptured vertebrobasilar dissecting aneurysms

The clinical characteristics of vertebrobasilar dissecting aneurysms occurring with subarachnoid hemorrhage (SAH) were reviewed in 42 patients, with particular focus on the time, incidence, and outcome in association with subsequent rupture. Twenty-nine patients underwent 31 surgical procedures, and the remaining 13 patients were managed without surgery. Surgical details included 19 proximal vertebral artery obliterations (including 1 case of endovascular surgery using balloon occlusion), 9 trappings, 1 wrapping, 1 bleb clipping, and 1 bleb clipping combined with wrapping. Surprisingly, subsequent rupture occurred in 30 (71.4%) of the 42 patients. Excluding one patient with postoperative rupture, 29 patients suffered a subsequent rupture in the unsecured stage. Of these 29 patients, 19 were operated on after the subsequent rupture and 10 were not operated on because of deteriorated clinical condition (9 patients) or anatomic considerations (1 patient). Of the 30 patients that suffered a subsequent rupture, 14 died. Twelve of the deaths were directly related to the second episode of rupture. Of the 12 patients who did not suffer a subsequent rupture, 10 underwent operations and there were no operative deaths. Only one patient died as the result of the initial critical SAH. The mortality (46.7%) of the patients with subsequent rupture was significantly higher (P < 0.05) than that (8.3%) of the patients without subsequent rupture. Seventeen (56.7%) of the 30 subsequent ruptures occurred within 24 hours after the first SAH, and 24 (80%) occurred within the first week. Six (66.7%) of the 9 patients operated on within 24 hours after the first SAH and 11 (68.8%) of the 16 patients operated on within a week suffered preoperative subsequent ruptures.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of epidermal growth factor (EGF), EGF receptor, and c-erbB-2 in human gastric cancer

The EGF stimulation system for growth regulation is implicated in normal and neoplastic cell proliferation. The role of EGF, the EGF receptor, and c-erbB-2 in human gastric cancer is reviewed on the basis of several reports, which have been mainly oriented toward their clinical significance. EGF has been shown immunohistochemically to be present in 26% of gastric cancers (n = 395). The presence of EGF in gastric cancer is correlated with the degree of gastric wall invasion and lymph node metastasis. The 5-year survival of patients with EGF-positive tumors is worse than that of patients with EGF-negative tumors. The presence of EGF in human gastric cancer may therefore represent a higher malignant potential. Fifteen percent of gastric cancers (n = 352) were also shown to be positive for both EGF and the EGF receptor immunohistochemically, and the simultaneous occurrence of EGF and the EGF receptor suggests that these tumors grow in an autocrine fashion. Tumors exhibiting EGF and the EGF receptor simultaneously show a greater degree of local invasion and lymph node metastasis. Increased expression of EGF receptor protein in gastric cancer appears to be related to biologic aggressiveness, although gene amplification has occurred only to a small extent. Twelve percent of gastric cancers (n = 486) were found to be positive for c-erbB-2. This type of tumor has a frequent metastasis, and patients with c-erbB-2-positive cancer have a poorer prognosis than those with c-erbB-2-negative tumors. Selective blockade of the EGF receptor and c-erbB-2 from their ligands with monoclonal antibodies (MoAbs) inhibits the growth of human gastric cancer xenografts. These MoAbs may therefore be effective antitumor agents against gastric cancer showing overexpression of EGF receptors or c-erbB-2.

Clinical significance of epidermal growth factor (EGF), EGF receptor, and c-erbB-2 in human gastric cancer

The EGF stimulation system for growth regulation is implicated in normal and neoplastic cell proliferation. The role of EGF, the EGF receptor, and c-erbB-2 in human gastric cancer is reviewed on the basis of several reports, which have been mainly oriented toward their clinical significance. EGF has been shown immunohistochemically to be present in 26% of gastric cancers (n = 395). The presence of EGF in gastric cancer is correlated with the degree of gastric wall invasion and lymph node metastasis. The 5-year survival of patients with EGF-positive tumors is worse than that of patients with EGF-negative tumors. The presence of EGF in human gastric cancer may therefore represent a higher malignant potential. Fifteen percent of gastric cancers (n = 352) were also shown to be positive for both EGF and the EGF receptor immunohistochemically, and the simultaneous occurrence of EGF and the EGF receptor suggests that these tumors grow in an autocrine fashion. Tumors exhibiting EGF and the EGF receptor simultaneously show a greater degree of local invasion and lymph node metastasis. Increased expression of EGF receptor protein in gastric cancer appears to be related to biologic aggressiveness, although gene amplification has occurred only to a small extent. Twelve percent of gastric cancers (n = 486) were found to be positive for c-erbB-2. This type of tumor has a frequent metastasis, and patients with c-erbB-2-positive cancer have a poorer prognosis than those with c-erbB-2-negative tumors. Selective blockade of the EGF receptor and c-erbB-2 from their ligands with monoclonal antibodies (MoAbs) inhibits the growth of human gastric cancer xenografts. These MoAbs may therefore be effective antitumor agents against gastric cancer showing overexpression of EGF receptors or c-erbB-2.

Clinical significance of epidermal growth factor (EGF), EGF receptor, and c-erbB-2 in human gastric cancer

The EGF stimulation system for growth regulation is implicated in normal and neoplastic cell proliferation. The role of EGF, the EGF receptor, and c-erbB-2 in human gastric cancer is reviewed on the basis of several reports, which have been mainly oriented toward their clinical significance. EGF has been shown immunohistochemically to be present in 26% of gastric cancers (n = 395). The presence of EGF in gastric cancer is correlated with the degree of gastric wall invasion and lymph node metastasis. The 5-year survival of patients with EGF-positive tumors is worse than that of patients with EGF-negative tumors. The presence of EGF in human gastric cancer may therefore represent a higher malignant potential. Fifteen percent of gastric cancers (n = 352) were also shown to be positive for both EGF and the EGF receptor immunohistochemically, and the simultaneous occurrence of EGF and the EGF receptor suggests that these tumors grow in an autocrine fashion. Tumors exhibiting EGF and the EGF receptor simultaneously show a greater degree of local invasion and lymph node metastasis. Increased expression of EGF receptor protein in gastric cancer appears to be related to biologic aggressiveness, although gene amplification has occurred only to a small extent. Twelve percent of gastric cancers (n = 486) were found to be positive for c-erbB-2. This type of tumor has a frequent metastasis, and patients with c-erbB-2-positive cancer have a poorer prognosis than those with c-erbB-2-negative tumors. Selective blockade of the EGF receptor and c-erbB-2 from their ligands with monoclonal antibodies (MoAbs) inhibits the growth of human gastric cancer xenografts. These MoAbs may therefore be effective antitumor agents against gastric cancer showing overexpression of EGF receptors or c-erbB-2.

Effect of gonadotropin-releasing hormone agonists, nafarelin, buserelin, and leuprolide, on experimentally induced endometriosis in the rat

OBJECTIVE -- The purpose of this study was to compare the potency of the gonadotropin-releasing hormone (GnRH) agonists nafarelin, buserelin, and leuprolide in a newly developed model of experimental endometriosis, thus further characterizing the model. METHODS -- Endometriosis was induced in female rats by autotransplantation of endometrium to a site under the renal capsule. The effect of the GnRH agonists on explant volume and fluid accumulation was evaluated. Binding affinities of the compounds for GnRH receptors in pituitary homogenates of female rats was also measured. RESULTS -- The three GnRH agonists induced significant atrophy and regression of endometriosis. The volume of endometriosis in intact control was 26.1 +/- 4.7 cu.-mm (n = 13), 1.7 +/- 0.1 cu.-mm (n = 12) after therapy with nafarelin, 4.8 +/- 1.8 cu.- mm (n = 7) with buserelin, and 3.7 +/- 1.2 cu.-mm (n = 13) with leuprolide. The effects of these compounds were comparable to that of castration (1.9 +/- 0.5 cu.-mm; n = 10). There was no significant difference in the binding affinities of leuprolide and buserelin for pituitary GnRH receptors. CONCLUSION -- The model was found to be responsive to the GnRH agonist agents evaluated and could discriminate between dosage levels. Potency of the compound seems to correlate with binding affinity to pituitary GnRH

Total recanalization of a spontaneously thrombosed arteriovenous malformation. Case report

The authors describe what they believe to be the first case of an asymptomatic, totally recanalized arteriovenous malformation (AVM) demonstrated by angiography 31 months after complete spontaneous thrombosis. The AVM, which initially became symptomatic with bleeding, had a 2-cm diameter nidus that was located within the inferior aspect of the left frontal lobe and was fed by branches from the left anterior cerebral and anterior ethmoid arteries. A single draining vessel flowed from the nidus into the anterior superior sagittal sinus. The AVM was surgically extirpated after recanalization. The authors stress the necessity for follow-up care for angiographically "cured" AVMs.

[A case of closed head injury with diffuse axonal injury, and oculomotor nerve avulsion and midbrain infarction]

We report an autopsy case of 66-year-old woman with closed head injury due to a fall from stairs. She had recovered after a half day period of coma following the fall. Severe right peripheral oculomotor nerve palsy was noted from the beginning. MRI demonstrated lesions in the corpus callosum and right midbrain. She had died of suffocation due to sputum impaction after 50 hours after the fall. Autopsy examination revealed traumatic subarachnoidal hemorrhage, partial tearing and petechial hemorrhage of the corpus callosum, and many axonal retraction balls scattered in the cerebral white matter. Avulsion of the right oculomotor nerve root and fresh midbrain infarct with hemorrhage in the territory of right paramedian artery were observed. Axonal retraction balls were densely distributed in the periphery of midbrain infarct. The distribution pattern of axonal retraction balls in the cerebrum was similar to that of damage due to shear strain in Holbourn's gelatin model of closed head injury. The midbrain infarct and oculomotor nerve avulsion may be due to both mechanical and ischemic damage during and after the fall. All of the lesions described above may be closely related to the rotatory force from the right forehead.

[Development of Wernicke's encephalopathy during the period of oral food intake after a subtotal colectomy for ulcerative colitis]

A 61-year-old woman was hospitalized because of ulcerative colitis which had caused fever, vomiting and diarrhea since June 16, 1992. Then she developed toxic megacolon, and was transferred to our hospital on the 1st of July and underwent subtotal colectomy the same day. After surgery, she received intravenous hyperalimentation (IVH) which contained 1,000 Kcal/day without vitamin supplementation. From the 8th to the 13th post-operative days, she took 3/4 or more of the liquid diet which contained 1,050 Kcal, protein 35 g, carbohydrate 166 g and vitamin B1 0.59 mg per day. From the 14th to the 23rd post-operative days, she ate 4/5 or more of the oral diet which contained 1,700 Kcal/day, protein 68 g, carbohydrate 236 g and vitamin B1 0.93 mg per day. During the 7th to the 23rd day, the IVH was reduced to 800 Kcal and then 500 Kcal per day. She talked less on the 19th post-operative day, and in a few days, her level of consciousness began to decline progressively. On the 27th post-operative day, neurological examinations revealed the following: semi-coma, almost fixed pupils which were 3 mm in diameter, absent doll's eye movement to all directions, flaccid extremities with abolished deep tendon reflexes. Pertinent abnormalities on laboratory data at that time consisted of hemoglobin 7.8 g/dl and serum total protein 5.4 g/dl. Lumbar puncture revealed normal cerebrospinal fluid under normal opening pressure. Cranial magnetic resonance imaging (MRI) taken on the 27th post-operative day demonstrated, on T2-weighted images, symmetrical high intensity lesions in the periventricular areas of the third and fourth ventricles, and periaqueductal area of the midbrain.(ABSTRACT TRUNCATED AT 250 WORDS)

Susceptibility of human T-lymphotropic virus type I infected cell line MT-2 to hepatitis C virus infection

To obtain a hepatitis C virus (HCV) proliferation system, we examined the susceptibility of various cultured cell lines to HCV infection. We found that a human T-lymphotropic virus type I infected cell line MT-2 was fairly sensitive to HCV infection. Using the polymerase chain reaction, intracellular positive-stranded HCV RNA was detected until at least 15 days postinoculation (p.i.). Intracellular negative-stranded HCV RNA was also detected at 10 days p.i., although not at 7 days p.i., suggesting that HCV is replicating in MT-2 cells 10 days p.i. Sequence analysis of hypervariable region 1 (HVR1) revealed that HVR1 sequences from cells 10 days p.i. had become homogeneous, although HVR1 sequences from the inoculum showed the typical quasi-species. We also found a lack of anti-HVR1 antibody against the HVR1 species which became homogeneous at 10 days p.i., although we easily detected antibody against the other HVR1 species obtained from the inoculum. These findings suggest that MT-2 cells are susceptible to HCV infection and are capable of supporting HCV replication.

Degeneration of the intrahippocampal routes of the perforant and alvear pathways in senile dementia of Alzheimer type

In five autopsied brains with senile dementia of Alzheimer type, the intrahippocampal routes of the perforant and alvear pathways were demonstrated by assessment of the distribution of isomorphic gliosis. Our results suggest that the perforant pathway goes along the stratum lacunosum-moleculare of the hippocampus proper to end in the dentate gyrus after perforating the prosubiculum but does not traverse the hippocampal sulcus, and that the alvear pathway enters into the stratum oriens of the hippocampus proper and the alveus from the white matter ventral to the subiculum.

Experimental dental caries on gnotobiotic inbred mice

The purpose of this study in mono-infected gnotobiotic BALB/cA and C3H/HeN mice was to evaluate the cariogenicity of Enterococcus faecalis. The caries incidence and mean caries score in the BALB/cA mice were significantly higher than those in the C3H/HeN. In both of the mouse strains, the mean number of E. faecalis isolated from the cecum content was almost the same, however, the mean number of E. faecalis from the maxilla of BALB/cA was significantly higher than that of C3H/HeN. These results indicate that C3H/HeN has some factors that prevent E. faecalis from attaching to the tooth surfaces.

Inhibition of viral multiplication in acute and chronic stages of infection by ribozymes targeted against the polymerase gene of mouse hepatitis virus

Two hammerhead ribozymes targeted against the polymerase gene of mouse hepatitis virus (MHV), which consisted of 22-nucleotide (nt) ribozyme core sequences and antisense sequences of different lengths, 243-nt (S-ribozyme) and 926-nt (L-ribozyme), were tested for their++ inhibitory effects on viral multiplication. Vectors that expressed the ribozymes were transfected into mouse DBT cells and several resulting cell lines constitutively expressing the ribozymes were selected and examined for intracellular MHV multiplication in acute and chronic stages of infection. The production of infectious progeny viral particles was significantly reduced in the transfected cell lines expressing either the S-ribozyme or L-ribozyme in acute infection. Although the in vitro cleavage process of the L-ribozyme was slower than that of the S-ribozyme, no difference was observed in inhibitory effects on MHV multiplication between S- and L-ribozymes in the transfected cells. In the transfected cells expressing L-ribozymes, production of viral particles was also inhibited in the chronic stage of MHV infection.

Styrene-induced hepatotoxicity in mice depleted of glutathione

In mice depleted of glutathione (GSH) by pretreatment with an inhibitor of GSH synthesis, buthionine sulfoximine (BSO; 1 hr before styrene, 2 mmol/kg or higher doses, ip), styrene (0.96-5.76 mmol/kg, po) produced hepatotoxicity characterized by an increase in serum alanine transaminase activity and cetrilobular necrosis of hepatocytes. Treatment with inhibitors of hepatic cytochrome P-450-dependent monooxygenases such as carbon disulfide, methoxsalen, piperonyl butoxide, and SKF-525A prevented or tended to reduce the hepatotoxic effect of styrene given in combination with BSO. Styrene 7,8-oxide (3.84 mmol/kg, po), a known metabolite of styrene, in combination with BSO caused an earlier and larger increase in SALT than that caused by an equimolar dose of styrene in combination with BSO. These results suggest that metabolism of styrene, possibly to styrene 7,8-oxide, is a necessary step in styrene-induced hepatotoxicity in GSH-depleted mice. Before the onset of hepatotoxicity, styrene in combination with BSO produced a larger and more prolonged depletion of hepatic GSH than that seen after the sole treatment with BSO or prolonged depletion of hepatic GSH than that seen after the sole treatment with BSO or styrene, but no depletion of hepatic protein sulfhydryls was induced by styrene in combination with BSO.