Traumatic ossicular chain discontinuity--report of two cases

In addition to hemotympanum and traumatic eardrum perforation, traumatic ossicular chain discontinuity should also be considered in the differential diagnosis of conductive hearing impairment resulting from head injury. The most common form of these ossicular chain lesions following head injury is incudostapedial joint (I-S joint) separation. We successfully managed two patients with I-S joint separation resulting from head injury through exploratory tympanotomy with ossiculoplasty within the recent 2 years. Both were young females who had sustained head injury resulting from traffic accident with the sequelae of persistent hearing impairment. They both gained significant hearing improvement postoperatively.

Outcome of liver transplantation in hepatitis C virus-infected patients who received hepatitis C virus-infected grafts

BACKGROUND & AIMS

The present organ shortage has brought into question the suitability of hepatitis C virus (HCV)-positive grafts. This study reviewed the outcome of such transplantations in our institution.

METHODS

Twenty-three HCV-positive patients who underwent orthotopic liver transplantation (OLT) for end-stage liver disease with HCV-positive grafts in 1992-1995 were studied. Only patients who survived more than 30 days were included in the analysis. Control group included 169 patients who underwent transplantation for HCV-related cirrhosis and received HCV-negative organs.

RESULTS

Patients who received HCV-infected organs had a cumulative survival rate of 89% and 72% at 1 and 5 years, respectively, vs. 88% and 73% for the control group (NS). There was no difference in graft survival, incidence of cirrhosis, mean hepatitis activity index score, fibrosis, or mean activity of serum transaminases. There was a trend toward lower incidence of recurrent hepatitis C in the study group compared with control (21% vs. 23% at 1 year and 47% vs. 64% at 5 years; NS). Patients in whom the donor strain became predominant after transplantation had significantly longer disease-free survival than patients who retained their own HCV strain (P < 0.003).

CONCLUSIONS

HCV-infected livers transplanted into HCV-infected recipients do not appear to convey a worse outcome in the initial years after OLT than HCV-negative grafts.

Quantification of recombinant core-like particles of bluetongue virus using immunosorbent electron microscopy

Immunosorbent electron microscopy was used to quantify recombinant baculovirus-generated bluetongue virus (BTV) core-like particles (CLP) in either purified preparations or lysates of recombinant baculovirus-infected cells. The capture antibody was an anti-BTV VP7 monoclonal antibody. The CLP concentration in purified preparations was determined to be 6.6 x 10(15) particles/l. CLP concentration in lysates of recombinant baculovirus-infected cells was determined at various times post-infection and shown to reach a value of 3 x 10(15) particles/l of culture medium at 96 h post-infection. The results indicated that immunosorbent electron microscopy, aided by an improved particle counting method, is a simple, rapid and accurate technique for the quantification of virus and virus-like particles produced in large scale in vitro systems.

Regulation of glycogen utilization in ischemic hearts after 24 hours of fasting

INTRODUCTION

Fasting protects the ischemic heart from injury and infarction. Previous studies have shown that hearts from fasted animals have greater glycogen utilization and a lower cytosolic redox state (NADH/NAD+) during global ischemia. While the mechanisms of increased glycogen utilization in fasted animals have not been elucidated, animals that hibernate or are tolerant of anoxia are known to increase the tissue content of the active form of glycogen phosphorylase, phosphorylase a. Therefore, this study was designed to (a) determine whether hearts from fasted animals have increased activity of glycogen phosphorylase during ischemia and (b) define those mechanisms responsible for this increase.

METHODS

Hearts isolated from either fed or fasted (24 h) rats were perfused and freeze-clamped at baseline, and after 1 and 10 min of ischemia, for measurement of phosphorylase activity, phosphorylase kinase activity, and glucose-6-phosphate concentrations.

RESULTS

Fasting increased the phosphorylase a/b ratio under both baseline and ischemic conditions. This increase was not accompanied by an increase in the activity of phosphorylase kinase, either with maximal [Ca2+] or under physiologic [Ca2+]. Glucose 6-phosphate concentrations were lower in hearts from fasted animals under baseline, but not ischemic, conditions.

CONCLUSIONS

Fasting enhances glycogen utilization during ischemia by increasing the active form of glycogen phosphorylase. This increase is not due to a change in phosphorylation by phosphorylase kinase nor end-product inhibition by G-6P. While the precise mechanism of increased glycogen phosphorylase activity in fasted animals is not clear, one likely explanation may be the lower cytosolic redox state demonstrated in the myocardium of fasted animals.

Inhibitory effect of gymnemic acid on intestinal absorption of oleic acid in rats

Gymnemic acid, a mixture of triterpene glycosides extracted from the leaves of Gymnema sylvestre, is known to inhibit the intestinal absorption of glucose in human and rats. This work examined the effect of gymnemic acid on oleic acid absorption by the method of intestinal perfusion in rats. The results showed the following. (i) Gymnemic acid potently inhibited the absorption of oleic acid in intestine. (ii) This inhibition was dose dependent and reversible. (iii) The extent of inhibition and the recovery progress were extremely similar to that of glucose absorption. (iv) Taurocholate did not affect the inhibitory effect of gymnemic acid on oleic acid absorption, but lowering its concentration facilitated the recovery from the inhibition. (v) The absorption of oleic acid was not affected by other glycosides such as phloridzin, stevioside, and glycyrrhizin. These new findings are important for understanding the roles of gymnemic acid in therapy of diabetes mellitus and obesity.

Analysis of hepatitis G virus/GB virus C quasispecies and replication sites in human subjects

Although the hepatitis G virus is unlikely to be a primary hepatotropic virus, its replication sites remain unclear. Using highly strand-specific Tth-based reverse transcriptase PCR we searched for the presence of the viral RNA negative strand in various autopsy tissues in two patients who died of end-stage liver disease. In addition, amplified viral sequences were compared in the 5' untranslated and the putative capsid regions by the single-strand conformation polymorphism (SSCP). Negative strand HGV RNA was detected in bone marrow and spleen from both patients and in lymph node tissue from one. All amplified sequences from a given patient were identical when compared by SSCP and direct sequencing. This lack of difference in the composition of quasispecies recovered from various tissues suggests the presence of a single, common viral compartment in the infected host.

Eliciting an immune response by plasmid DNA encoding a human sperm protein (HSD-1)

The cDNA encoding a human sperm membrane designated as HSD-1 was isolated from a human testis lambda gt11 cDNA expression library and assigned the accession number U12978 by GenBank. HSD-1 was conjugated to an eukaryotic expression plasmid (pRSV) to construct the recombinant plasmid pRSV-HSD-1. Female mice were inoculated intramuscularly with the plasmid DNA and the expression of HSD-1 was determined. HSD-1 mRNAs were detected in myocytes and endomysial connective tissue cells of the quadriceps muscle by in situ hybridization. Spleen of inoculated animals contained an increased number of cytotoxic T lymphocytes, phagocytes, and plasma cells. Fertility of the treated animals was not affected. Thus, intramuscular inoculation of female mice with the plasmid DNA (pRSV-HSD-1) results in the expression of HSD-1 and may elicit a tissue-mediated immune response.

Repetitive acidosis protects the ischemic heart: implications for mechanisms in preconditioned hearts

Repetitive brief ischemic episodes (ischemic preconditioning, PC) result in transient intracellular acidosis and protect the heart from subsequent ischemic injury, potentially through a protein kinase C (PKC)-dependent mechanism. We hypothesized that repetitive brief acidification of the heart without concomitant ischemia would also protect the heart from ischemic injury via a PKC-dependent mechanism. Isolated rat hearts underwent 30 min of global ischemia following control perfusion (CTL), or after PC or repetitive acidosis (RA), in the presence of absence of chelerythrine, a specific PKC inhibitor. Intracellular pH, PCr and ATP were measured using 31P NMR spectroscopy, while intracellular sodium [Na]i was measured using 23Na spectroscopy. Na,K-ATPase activity was measured prior to ischemia and on reperfusion. Both PC and RA resulted in transient acidification prior to ischemia. Ischemic injury, as assessed by creatinine kinase (CK) release on reperfusion, was reduced in both the PC and RA hearts [63+/-14 and 16+/-4 IU/g dry weight (dw) respectively, v 705+/-72 IU/gdw for control P<0.001], and was associated with improved functional recovery on reperfusion. PC and RA each significantly reduced Na,K-ATPase activity prior to ischemia (8.18+/-0.47 and 7.76+/-0.54 micromol ADP/h/mg protein) when compared to control (11.05+/-0.54 micromol ADP/h/mg protein P<0.05), limited the rate of ATP depletion during ischemia, and resulted in more rapid normalization of [Na]i on reperfusion. Chelerythrine resulted in intermediate CK release in PC and RA hearts (443+/-48 and 375+/-72 IU/gdw, P<0.001 v PC, P<0.01 v control), but did not alter the rate of ATP depletion or [Na]i kinetics in either PC or RA hearts. PC and RA each protect the ischemic heart, having in common ATP preservation during ischemia and more rapid normalization of [Na]i on reperfusion. These effects, not modulated by protein kinase C, are consistent with the hypothesis that ATP preservation during ischemia provides enhanced substrate for sodium efflux via the Na,K-ATPase on reperfusion.

Differences between hepatitis C virus 5' untranslated region quasispecies in serum and liver

It is unclear whether the sequence populations of hepatitis C virus (HCV) quasispecies in the liver and in serum are different, as a variety of studies on this subject provide conflicting results. In the current study, the populations of HCV 5' untranslated region (5' UTR) sequences in paired serum and liver samples from six patients with chronic hepatitis were analysed. Liver-derived, negative-strand viral RNA was amplified with a highly strand-specific Tth-based assay, and extensive measures, including accounting for template copy number, were undertaken to lower the risk of sporadic artefactual polymorphism. Amplified sequences were compared by single-strand conformation polymorphism analysis and by direct sequencing of identified differences. In four patients, liver samples were found to contain variants within the quasispecies which were not found in serum or negative-strand viral RNA, while in the remaining two patients, low virus titre prevented a reliable quasispecies analysis. These results suggest the presence in the same individual of HCV variants differing in the 5' UTR and possibly replicating with different kinetics.

Expression and characterization of an epididymis-specific gene

A truncated cDNA coding a rabbit epididymal protein (BE-20) was identified in a previous study. In the present study the full-length cDNA was isolated by the method of rapid amplification of cDNA ends. The BE-20 cDNA consisted of 585 bp with a poly(A) tail of 26 residues and an open reading frame composed of 369 bp encoding a deduced polypeptide containing 123 amino acid residues with a calculated molecular mass of 13 kDa. The N-terminus-contained a leucine-rich segment. BE-20 cDNA has about 76.8% homology with the HE4 gene of human epididymis. Northern blot analysis of mRNAs prepared from 17 different human tissues was performed using as probe a 0.5-kb DNA fragment corresponding to a segment of BE-20 cDNA. Positive reaction was elicited only with epididymal mRNA. A DNA fragment corresponding to a section of the open reading frame of BE-20 cDNA was cloned in Escherichia coli under the control of the T7 promoter. The cellular content of the expressed recombinant protein comprised about 55% of the total protein. The chromatographically purified bacterial product migrated as a single band with an estimated M(r) of 15 kDa on analysis by SDS-PAGE. In conclusion, BE-20 cDNA is expressed only in the epididymis. It is structurally related to the four-disulfide core family of extracellular proteinase inhibitors and may be involved in sperm maturation.

Molecular cloning and characterization of a novel testis-specific nucleoporin-related gene

A 20-kDa sperm membrane protein cDNA, designated as RSD-1, was isolated by epitope selection from a rat testis lambda gtll expression library. RSD-1 was used as a probe to screen a human testis lambda ZAPII cDNA expression library. A cDNA designated as BS-63 was isolated and found to consist of 1933 bp with an open reading frame of 1824 bp and assigned the accession number U64675 by GenBank. The deduced polypeptide consisted of 608 amino acid residues containing XFXFG or FG motifs that are characteristic of nuclear pore complex (NPC) proteins and act as potential binding sites for Ran. The N-terminal region has high homology with RanBP2/Nup358, a nucleoporin component, showing that BS-63 is a member of the NPC family. Northern blot analysis of mRNAs prepared from various human tissues shows that BS-63 is transcribed in two forms: 6.0 and 8.5 kb. The 8.5-kb transcript was present in low amounts in several somatic tissues, whereas the 6.0-kb transcript is expressed only in testis. In situ hybridization analysis of human testis sections showed that BS-63 mRNA is expressed only in germ cells at all stages of spermatogenesis. Sertoli cells did not transcribe the gene.

Hepatitis C virus in peripheral blood mononuclear cells from a chronically infected patient receiving liver graft from infected donor

BACKGROUND

In hepatitis C virus (HCV)-positive patients receiving HCV-positive liver allografts either the donor or recipient strain overtakes the other strain. Whether these changes are reflected in peripheral blood mononuclear cell (PBMC)-associated virus is unknown.

METHODS

We analyzed by single-strand conformation polymorphism and sequencing HCV RNA from serum and PBMCs from a liver transplant recipient whose indigenous strain was replaced by the donor strain.

RESULTS

Only the recipient strain was detectable in serum and PBMCs 3 and 5 days after transplantation; at day 7 and 8, a mixture of both was present in the PBMCs, but only recipient strain was detectable in serum. This coincided with the peak presence of donor DNA in recipient PBMCs. From day 14 on, HCV sequences in serum and PBMCs were indistinguishable.

CONCLUSIONS

Overtake phenomenon in the setting of liver transplantation from infected donors to infected recipients is manifested in PBMCs. Cells released from infected graft carry donor HCV strain.

Mutagenicity and aromatic amine content of fumes from heated cooking oils produced in Taiwan

According to toxicological studies, there are several unidentified mutagens derived from cooking oil fumes appearing in kitchens of Chinese homes where women daily prepare food. Data are limited to an analysis of aromatic amines from cooking oil fumes, which are known to be carcinogenic for bladder cancer. Fume samples from three different commercial cooking oils frequently used in Taiwan were collected and analysed for mutagenicity in the Salmonella/microsome assay. Aromatic amines were extracted from the samples and identified by HPLC and confirmed by gas chromatography/mass spectrometry (GC/MS). Extracts from three cooking oil fumes were found to be mutagenic in the presence of S-9 mix. All samples contained 2-naphthylamine (2-NA) and 4-aminobiphenyl (4-ABP). Concentrations of 2-NA and 4-ABP were 31.5 and 35.7 microg/m3 in fumes from sunflower oil, 31.9 and 26.4 mg/m3 in vegetable oil, and 48.3 and 23.3 microg/m3 in refined-lard oil, respectively. Mutagenicities of the three cooking oil condensates were significantly reduced (P<0.05) by adding the antioxidant catechin (CAT) into the oils before heating. Significant difference existed between the amounts of aromatic amines with and without adding CAT (P<0.05). These results indicate that exposure to cooking oil fumes in Taiwan might be an important but controllable risk factor in the aetiology of bladder cancer.

Detection and sequence analysis of hepatitis B virus integration in peripheral blood mononuclear cells

A PCR-based technique was used to detect hepatitis B virus (HBV) integration in peripheral blood mononuclear cells from patients with chronic hepatitis B. Integrated HBV DNA sequences, with virus-cell junctions located in the cohesive region between direct repeat 1 (DR1) and DR2, were found in 2 of 10 studied patients.

Epicutaneous administration of hapten through patch application augments TH2 responses which can downregulate the elicitation of murine contact hypersensitivity

BACKGROUND AND OBJECTIVE

Allergic contact dermatitis and its animal model, contact hypersensitivity (CHS), have long been documented as type 1 T-cell-predominant immune responses. Although type 1/type 2 T-cell deviation has been repeatedly demonstrated to play an important role in many human diseases and their animal models, the potential of tilting type 1/type 2 T-cell differentiation of CHS by modulating the manner of administration and dosage of hapten remains unexplored. This study examined the effect of these two factors on type 1/type 2 balance of CHS.

METHODS

ELISA methods for detection of isotypes of hapten-specific antibodies and cytokine profiles of in vitro reactivation culture as well as ear-swelling assay were used to indicate type 1 or type 2 T-cell immune responses.

RESULTS

In this paper, it was demonstrated that dosage of hapten has no effect on the type 1/ type 2 T-cell balance of CHS, whereas epicutaneous administration of hapten through patch application could tilt the type 1/type 2 balance to decrease type 1 and to augment type 2 T-cell responses. Patch application-induced modulation is still effective in ever-sensitized mice and the augmented type 2 T-cell responses are persistent and increase progressively in strength after repeated immunizations. Moreover, it was demonstrated that the augmented type 2 T-cell response can downregulate the elicitation of CHS. The major mediating cells of the enhanced type 2 T-cell responses were determined to be CD4+ T cells (TH2 cells).

CONCLUSIONS

These data show that epicutaneous administration of hapten through patch application augments TH2 response which can downregulate the elicitation of murine CHS. This exploration may contribute to the understanding of regulatory mechanisms involved in contact allergy.

A novel Bacillus subtilis gene, antE, temporally regulated and convergent to and overlapping dnaE

A Bacillus subtilis promoter, Px, that functions in a convergent manner with the sigA operon promoter P3 has been found in the sigA operon. Promoter Px is turned on at the same time as promoter P3 during early sporulation. The transcript from promoter Px codes for a small protein with partial homology to the OmpR protein from Escherichia coli and also carries an untranslated sequence at its 3' end that is complementary to the 5' end of the P3 transcript, which codes for the ribosome binding site of dnaE. The gene controlled by Px has been called antE. The expression of antE does not require sigmaB, sigmaE, or sigmaH. Px was transcribed in vitro by the sigmaA holoenzyme and is the seventh promoter to be recognized in the sigmaA operon. A possible role for the antE gene during early sporulation is proposed.

The attachment protein of Hendra virus has high structural similarity but limited primary sequence homology compared with viruses in the genus Paramyxovirus

The complete nucleotide sequence of the attachment protein gene of Hendra virus, a new member of the subfamily Paramyxovirinae, has been determined from cDNA clones derived from viral genomic RNA. The deduced mRNA is 2565 nucleotides long with one open reading frame encoding a protein of 604 amino acids, which is similar in size to the attachment protein of the members of the subfamily. However, the mRNA transcript is >600 nucleotides longer than others in the subfamily due to the presence of long untranslated regions at both the 5' and 3' ends. The protein is designated G because it lacks both hemagglutination and neuraminidase activities. It contains a hydrophobic transmembrane domain close to the N terminus, eight potential N-linked glycosylation sites, and 18 cysteine residues. Although the HeV G protein had low sequence homology with Paramyxovirinae members, the predicted folding pattern of its extracellular globular head was very similar to that of members of the genus Paramyxovirus, with the location of seven potential pairs of sulfide bonds absolutely conserved. On the other hand, among the seven residues known to be critical for neuraminidase activity, only one was conserved in the Hendra virus G protein compared with at least six in HN proteins of paramyxoviruses and rubulaviruses and four in H proteins of morbilliviruses. The biological significance of this finding is discussed.

Search for hepatitis C virus extrahepatic replication sites in patients with acquired immunodeficiency syndrome: specific detection of negative-strand viral RNA in various tissues

The existence of extrahepatic reservoirs of hepatitis C virus (HCV) replication remains highly controversial. We searched for the presence of HCV-RNA negative strand in various tissues from eight HCV-infected patients who died of acquired immunodeficiency syndrome (AIDS)-related complications. Negative-strand RNA was detected by a Tth-based reverse-transcriptase polymerase chain reaction (RT-PCR), which was optimized for sensitivity and strand specificity on synthetic RNA templates. This assay was capable of detecting about 10(2) genomic Eq molecules of the correct strand while unspecifically detecting >/=10(8) genomic Eq molecules of the incorrect strand. Negative-strand viral RNA was detected in all but one liver, in lymph nodes (5 cases), in pancreas (5 cases), in adrenal gland (2 cases), in thyroid (2 cases), in bone marrow (1 case), and in spleen (1 case). These data suggest a possible presence of HCV replication sites outside the liver, at least in AIDS patients. Whether these findings relate to various extrahepatic manifestations of HCV infection remains to be determined.

Inhibitory effect of gymnemic acid on intestinal absorption of oleic acid in rats

Gymnemic acid, a mixture of triterpene glycosides extracted from the leaves of Gymnema sylvestre, is known to inhibit the intestinal absorption of glucose in human and rats. This work examined the effect of gymnemic acid on oleic acid absorption by the method of intestinal perfusion in rats. The results showed the following. (i) Gymnemic acid potently inhibited the absorption of oleic acid in intestine. (ii) This inhibition was dose dependent and reversible. (iii) The extent of inhibition and the recovery progress were extremely similar to that of glucose absorption. (iv) Taurocholate did not affect the inhibitory effect of gymnemic acid on oleic acid absorption, but lowering its concentration facilitated the recovery from the inhibition. (v) The absorption of oleic acid was not affected by other glycosides such as phloridzin, stevioside, and glycyrrhizin. These new findings are important for understanding the roles of gymnemic acid in therapy of diabetes mellitus and obesity.

Distinct tumor necrosis factor-alpha responses in alveolar and peritoneal macrophages are associated with local levels of endotoxin

Tumor necrosis factor alpha (TNF-alpha) responses of alveolar macrophages (AMs) and peritoneal macrophages (PMs) were studied in rats after intravenous injection of lipopolysaccharide (LPS). High levels of plasma TNF-alpha, increased pulmonary myeloperoxidase activity, and leukopenia occurred within 2 h after LPS injection. Alveolar spaces exhibited a strict compartment property, as manifested by only slightly increased LPS and TNF-alpha levels in alveolar lavage fluid and an unchanged capacity of AMs to produce TNF-alpha. By contrast, the peritoneal cavity had greatly increased local LPS and TNF-alpha levels and a diminished PMs TNF-alpha response to LPS. The amount of LPS in the alveolar spaces was less than 0.2% of the level in peritoneal fluid. These results indicate that activation of resident macrophages is dependent on the amounts of local LPS and, in addition, suggest that resident AMs neither participate in the plasma TNF-alpha response nor contribute to neutrophil sequestration in the lung during the early stages of endotoxemia.

The presence of active hepatitis C virus replication in lymphoid tissue in patients coinfected with human immunodeficiency virus type 1

The existence of extrahepatic replication sites of hepatitis C virus (HCV) remains controversial. Highly strand-specific Tth-based reverse transcriptase-polymerase chain reaction was used to search for the presence of viral RNA negative strand in lymph nodes from 16 patients with AIDS and in peripheral blood mononuclear cells (PBMC) from 14 other human immunodeficiency virus (HIV)-positive patients. Negative-strand HCV RNA was detected in lymph node samples from 10 patients (63%) and in PBMC from 5 (36%). This suggests that, at least under circumstances of impaired immunity associated with HIV infection, HCV is lymphotropic in vivo. However, the clinical implications of these findings need to be further investigated.

Detection of hepatitis C virus replication in peripheral blood mononuclear cells after orthotopic liver transplantation

BACKGROUND

The presence of hepatitis C virus (HCV) replication in peripheral blood mononuclear cells (PBMCs) remains controversial. We determined the presence of the negative HCV RNA strand in PBMCs from a group of HCV-positive patients before and after liver transplantation.

METHODS

Nine patients receiving orthotopic liver transplantation for end-stage HCV-related liver disease were studied. PBMCs were collected on the day of transplantation and 1 month later. The negative HCV RNA strand was detected by highly strand-specific Tth-based reverse transcriptase polymerase chain reaction.

RESULTS

All nine patients were positive for the presence of the HCV RNA-positive strand in serum and PBMCs both before and after transplantation. The presence of the negative HCV RNA strand was documented in three PBMC samples after transplantation but in none of the samples collected before transplantation.

CONCLUSION

Our results suggest that under circumstances of impaired immunity associated with pharmacological immunosuppression, HCV may be lymphotropic in vivo.

Gene encoding a human testis Sertoli cell component related to LIM domain protein

The cDNA (HED-2) encoding a 20 kDa protein found in mammalian epididymal fluid was isolated from a human testis expression library. It is composed of 1908 bp, containing a reading frame of 1479 bp, coding a polypeptide consisting of 493 amino acids, and assigned the accession number: U15158 by GenBank (Biochem. Mol. Biol. Int. 34, 1131-1136, 1994). HED-2 has 99% identity with the zyxin gene in amino acid sequence, a component of cell junction matrix and a member of the LIM domain protein family. Northern blot analysis of RNAs prepared from various human tissues showed that the HED-2 gene was expressed in all tissues analyzed. Sertoli cells of human testis expressed the gene as determined by an in situ hybridization method. The present study shows that the HED-2 gene is a member of the LIM domain protein family.

Hepatitis C virus quasispecies in patients infected with HIV-1: correlation with extrahepatic viral replication

Hepatitis C virus (HCV) sequences recovered from serum, peripheral blood mononuclear cells (PBMCs), and various tissues from human immunodeficiency virus type 1 (HIV-1) positive patients were compared by single strand conformational polymorphism (SSCP) and sequencing. In five patients, paired serum and PBMCs samples were analyzed while in two other patients multiple autopsy tissues were studied. Sequences amplified from the NS5 and E2 regions were consistently identical in the same patient; however, three PBMCs samples and three different tissue samples (pancreas and adrenal gland in one patient and lymph node in the other patient) contained 5' untranslated region (5'UTR) sequences that were different from circulating sequences. The presence of 5' UTR sequences differing from circulating sequences correlated with the presence of HCV RNA negative strand, as the latter was detected by a Tth-based strand-specific assay in all but one of these samples. These two independent lines of evidence: viral sequence differences and the presence of RNA negative strand in the same tissues strongly argue for the genuine presence of extrahepatic HCV replication, at least in the setting of HIV-1 infection.

Expression of equine morbillivirus (EMV) matrix and fusion proteins and their evaluation as diagnostic reagents

Full-length cDNA clones coding for the matrix (M) and fusion (F) proteins of equine morbillivirus (EMV) were isolated by RT-PCR, and expressed in Escherichia coli using two different expression systems. Western blot analysis indicated that the M and F proteins, expressed either by itself or as fusion proteins with glutathione S-transferase (GST), were insoluble and degraded after expression. Analysis of the degradation pattern of recombinant M protein suggested that the N-terminus of the matrix protein might be more stable and antigenic than the C-terminal region. Therefore a third system was used to express a truncated M protein, composed of the N-terminal amino acid residues 1-197, with a (His)6-tag attached at the N-terminus. This recombinant protein [(His)6-Mtr], was stable but was also insoluble. After one-step affinity purification under denaturing conditions, (His)6-Mtr was used to monitor the antibody response to EMV infection by Western blot and ELISA. We obtained a 100% correlation between Western blot and virus neutralisation testing although the number of positive sera available for testing was very limited, which included seven horse, two rabbit and one human sera.

Nitro-polycyclic aromatic hydrocarbon contents of fumes from heated cooking oils and prevention of mutagenicity by catechin

According to earlier studies, fumes from cooking oils were found to be mutagenic and several polycyclic aromatic hydrocarbons (PAHs), (benzo(a)pyrene (B(a)P), benz(a)antracene (B(a)A), and dibenz(a,h)anthracene (DB(ah)A)) were identified. Fume samples from three different commercial cooking oils frequently used in Taiwan were collected and nitro-polycyclic aromatic hydrocarbons (NPAHs) were extracted from the samples and identified by HPLC chromatography. Extracts from three cooking oil fumes contained 1-nitropyrene (1-NP) and 1,3-dinitropyrene (1,3-DNP). Concentrations of 1-NP and 1,3-DNP were 1.1 +/- 0.1 and 0.9 +/- 0.1 micrograms/m3 in fumes from lard oil, 2.9 +/- 0.3 and 3.4 +/- 0.2 micrograms/m3 in soybean oil, 1.5 +/- 0.1 and 0.4 +/- 0.1 micrograms/m3 in peanut oil, respectively. The preventive effect of three natural antioxidants (gamma-tocopherol (TOC), lecithin (LEC), and catechin (CAT)) for the reduction of mutagenicity and amounts of PAHs and NPAHs of fumes from cooking oils were evaluated. Mutagenicity of cooking oil fumes occurred, and the concentration of B(a)P were significantly reduced (p < 0.05), by adding CAT into cooking oils before heating. B(a)A, DB(ah)A, and two NPAHs were not detected when the concentration of CAT was 500 ppm in all three cooking oil fumes. These results indicate that fumes of cooking oils contained PAHs and NPAHs that may be a risk factor for lung cancer among cooks and the carcinogens could be reduced by adding the natural antioxidant, catechin.

Sequence analysis of the Hendra virus nucleoprotein gene: comparison with other members of the subfamily Paramyxovirinae

The nucleoprotein (N) gene of Hendra virus (HeV), an unclassified member of subfamily Paramyxovirinae in the family Paramyxoviridae previously known as equine morbillivirus, was cloned and sequenced. The majority of the deduced amino acid sequence was further confirmed by direct sequencing of peptide fragments of the N protein derived from purified virions. The 3' untranslated sequence of the HeV N gene mRNA was 568 nt and was much longer than that observed in other Paramyxovirinae. The N protein was 532 amino acids in length with a molecular mass of 58.5 kDa. Although the HeV N protein had a slightly higher amino acid sequence identity to those of the genus Morbillivirus than to those of other Paramyxovirinae genera, the level of identity was much lower than that observed within the morbilliviruses. Our results indicated that HeV could not confidently be classified as a member of the genus Morbillivirus, Paramyxovirus or Rubulavirus and suggest that the virus be classified in a new genus within the Paramyxovirinae.

An immunogenic epitope of Chlamydia pneumoniae from a random phage display peptide library is reactive with both monoclonal antibody and patients sera

Random 15-mer peptides displayed on filamentous phages were screened in binding studies using a Chlamydia pneumoniae-specific monoclonal antibody (RR-402) and affinity-purified, polyclonal sera from patients seropositive for C. pneumoniae infections by the microimmunofluorescence (MIF) test. One 15-mer epitope, epitope Cpnl5A (LASLCNPKPSDAPVT) was identified in both the monoclonal and polyclonal screenings, and showed higher ELISA reactivity with C. pneumoniae MIF-positive sera compared to patients with other chlamydial infections, non-chlamydial respiratory infections and normal healthy sera (MIF-negative). Interestingly, epitope Cpnl5A also showed significant (52%) amino acid sequence homology to the 56 kDa type-specific antigen of Rickettsia tsutsugamushi, a protein implicated in the virulence of this organism.

Metabolism of the lipid peroxidation product, 4-hydroxy-trans-2-nonenal, in isolated perfused rat heart

The metabolism of 4-hydroxy-trans-2-nonenal (HNE), an alpha, beta-unsaturated aldehyde generated during lipid peroxidation, was studied in isolated perfused rat hearts. High performance liquid chromatography separation of radioactive metabolites recovered from [3H]HNE-treated hearts revealed four major peaks. Based on the retention times of synthesized standards, peak I, which accounted for 20% radioactivity administered to the heart, was identified to be due to glutathione conjugates of HNE. Peaks II and III, containing 2 and 37% radioactivity, were assigned to 1, 4-dihydroxy-2-nonene (DHN) and 4-hydroxy-2-nonenoic acid, respectively. Peak IV was due to unmetabolized HNE. The electrospray ionization mass spectrum of peak I revealed two prominent metabolites with m/z values corresponding to [M + H]+ of HNE and DHN conjugates with glutathione. The presence of 4-hydroxy-2-nonenoic acid in peak III was substantiated using gas chromatography-chemical ionization mass spectroscopy. When exposed to sorbinil, an inhibitor of aldose reductase, no GS-DHN was recovered in the coronary effluent, and treatment with cyanamide, an inhibitor of aldehyde dehydrogenase, attenuated 4-hydroxy-2-nonenoic acid formation. These results show that the major metabolic transformations of HNE in rat heart involve conjugation with glutathione and oxidation to 4-hydroxy-2-nonenoic acid. Further metabolism of the GS-HNE conjugate involves aldose reductase-mediated reduction, a reaction catalyzed in vitro by homogenous cardiac aldose reductase.

Detection of hepatitis G virus replication sites by using highly strand-specific Tth-based reverse transcriptase PCR

The replication sites of the recently discovered hepatitis G virus (HGV) remain unknown. Using highly strand-specific Tth-based reverse transcriptase PCR, we searched for the presence of viral RNA negative strand in multiple autopsy tissues from four patients with AIDS and in peripheral blood mononuclear cells from six other human immunodeficiency virus-positive patients. Negative-strand HGV RNA was detected in three of four bone marrow samples, in two of two spleen samples, and in one of four liver tissue samples. However, the specific cellular site of replication within the positive tissues was not determined. This study does not support HGV as a primary hepatotropic virus.

Association between hepatitis B virus core promoter rearrangements and hepatocellular carcinoma

Hepatitis B virus (HBV) is the major etiological agent of hepatocellular carcinoma (HCC). Whether any particular viral variants are associated with HCC is unknown. We studied 53 Gambian patients with HCC and 33 HBsAg positive controls. A functional part of HBV core promoter and whole precore region were sequenced directly and/or after cloning. HBV DNA was amplified from sera from 27 HCC patients and in all controls. Fourteen (52%) patients and 12 (36%) controls (NS) were found to harbor an HBV strain with G to A transition mutation at position 1896 leading to HBeAg negative phenotype. Nine (33%) HCC patients and 2 (6%) controls (p < 0.01) harbored a mixture of wild type and HBV strains with deletions/insertions; strong consensus sequences for topoisomerase I breakage were located in the vicinity of these changes. In Africa, HCC is associated with HBV strains that have deletions/insertions in the HBV core promoter region.

Hepatitis G virus coinfection in chronic hepatitis B and C patients in Poland

This study evaluated the epidemiology and impact of hepatitis G virus (HGV) infection in patients with chronic hepatitis B and C. Serum samples were obtained from 128 consecutive untreated patients with chronic hepatitis B (72 cases) or C (56 cases). The presence of HGV RNA was determined by PCR amplification of the 5'untranslated region; the sensitivity of the assays was ten template copy equivalents. The prevalence of HGV RNA in hepatitis B and C was found to be 25% and 34%, respectively. HGV-positive and HGV-negative patients did not differ with respect to risk factors for infection, age, sex, or alanine aminotransferase activity. Similarly, there was no difference in the severity of liver disease, as assessed with HAI score. In conclusion, we found a very high prevalence of HGV infection in chronic hepatitis B and C patients in Poland. Nevertheless, no evidence was found that HGV coinfection has any impact on the severity of the underlying disease.

Lack of evidence for GB virus C/hepatitis G virus replication in peripheral blood mononuclear cells

BACKGROUND/AIMS

The recently identified hepatitis G virus (HGV) has been found to be common in patients with various forms of chronic liver disease, particularly chronic hepatitis C. However, replication sites of this new viral agent have not been studied.

METHODS

We searched for the presence of HGV RNA in peripheral blood mononuclear cells and serum samples from nine chronic hepatitis C patients coinfected with hepatitis G virus. The presence of negative viral RNA strands was determined by strand-specific Tth-based assay which was optimized on synthetic template.

RESULTS

All peripheral blood mononuclear cell samples were negative for the presence of the HGV RNA minus strand and only five were positive for the presence of the positive strand, albeit at a low level of 10-10(2) genomic equivalents/10(6) cells.

CONCLUSIONS

These findings imply that hepatitis G virus does not replicate in peripheral blood mononuclear cells, at least in the population of HCV/HGV coinfected patients.

A novel P/V/C gene in a new member of the Paramyxoviridae family, which causes lethal infection in humans, horses, and other animals

In 1994, a new member of the family Paramyxoviridae isolated from fatal cases of respiratory disease in horses and humans was shown to be distantly related to morbilliviruses and provisionally called equine morbillivirus (K. Murray et al., Science 268:94-97, 1995). To facilitate characterization and classification, the virus was purified, viral proteins were identified, and the P/V/C gene was cloned and sequenced. The coding strategy of the gene is similar to that of Sendai and measles viruses, members of the Paramyxovirus and Morbillivirus genera, respectively, in the subfamily Paramyxovirinae. The P/V/C gene contains four open reading frames, three of which, P, C, and V, have Paramyxovirinae counterparts. The P and C proteins are larger and smaller, respectively, than are cognate proteins in members of the subfamily, and the V protein is made as a result of a single G insertion during transcription. The P/V/C gene has two unique features. (i) A fourth open reading frame is located between those of the C and V proteins and potentially encodes a small basic protein similar to those found in some members of the Rhabdoviridae and Filoviridae families. (ii) There is also a long untranslated 3' sequence, a feature common in Filoviridae members. Sequence comparisons confirm that although the virus is a member of the Paramyxovirinae subfamily, it displays only low levels of homology with paramyxoviruses and morbilliviruses and negligible homologies with rubulaviruses.

The influence of hepatitis C virus genotypes on the outcome of liver transplantation

BACKGROUND

The aim of this study was to report the influence of hepatitis C virus (HCV) genotypes and HLA matches on the outcome of liver transplantation, hepatitis recurrence, and progression to cirrhosis after transplantation.

METHODS

HCV genotypes were determined from pretransplantation sera and/or liver explant tissues from 202 patients with HCV-related end-stage liver disease. One hundred fifty patients with known infecting genotype for whom posttransplantation biopsy specimens were available or who had normal results of liver injury tests constituted the group analyzed. Patients were followed up for up to 4.5 years. Hepatitis activity index scores at the time of disease recurrence were used to assess disease activity. Cirrhosis was diagnosed by using histological evidence. The number of HLA matches with respect to A, B, DR, and DQ loci was determined.

RESULTS

The rates of hepatitis recurrence were 25% and 75% at 1 year and 4 years, respectively; Kaplan-Meier survival analysis did not reveal significant differences between the infecting genotypes with respect to overall rates of survival or recurrence of hepatitis. At hepatitis recurrence, hepatitis activity index scores did not differ between the genotype groups. The distribution of infecting genotypes among the 7 patients who developed cirrhosis is reflective of pretransplantation distribution. Neither HLA site-specific nor total matches affected the rates of survival or disease recurrence.

CONCLUSIONS

The infecting HCV genotype had no influence on the incidence or severity of recurrent hepatitis, rate of survival, or development of cirrhosis. HLA matching does not influence transplantation outcome for HCV-related disease.

Hepatitis G virus infection in American patients with cryptogenic cirrhosis: no evidence for liver replication

It is unclear whether hepatitis G virus (HGV) can lead to chronic liver disease and cirrhosis. Eighty-nine patients with end-stage liver disease undergoing liver transplantation were studied: 50 were diagnosed as having cryptogenic cirrhosis while 39 had nonviral chronic liver disease. Five (10%) in the former and 1 (2.6%) in the latter group (not significantly different) were positive for HGV RNA in serum. All 6 HGV-infected patients were negative for the presence of the HGV RNA minus strand in the liver when tested with a strand-specific Tth-based reverse transcription-polymerase chain reaction, and 5 were positive for the presence of the plus strand, albeit at low levels. This implies that the liver is not the primary replication site for HGV, at least in a significant proportion of patients. Absence of liver replication explains the reported lack of association between HGV infection and liver pathology encountered in many clinical settings.

Mutagenicity and polycyclic aromatic hydrocarbon content of fumes from heated cooking oils produced in Taiwan

According to epidemiologic studies, exposure of women to fumes from cooking oils appears to be an important risk factor for lung cancer. Fume samples from three different commercial cooking oils frequently used in Taiwan were collected and analyzed for mutagenicity in the Salmonella/microsome assay. Polycyclic aromatic hydrocarbons were extracted from the samples and identified by HPLC chromatography. Extracts from three cooking oil fumes were found to be mutagenic in the presence of S9 mix. All samples contained dibenz[a,h]anthracene (DB[a,h]A) and benz[a]anthracene (B[a]A). Concentration of DB[a,h]A and B[a]A were 1.9 and 2.2 micrograms/m3 in fumes from lard oil, 2.1 and 2.3 micrograms/m3 in soybean oil, 1.8 and 1.3 micrograms/m3 in peanut oil, respectively. Benzo[a]pyrene (B[a]P) was identified in fume samples of soybean and peanut oil, in concentrations of 19.6 and 18.3 micrograms/m3, in this order. These results provide experimental evidence and support the findings of epidemiologic observations, in which women exposed to the emitted fumes of cooking oils are at increased risk of contracting lung cancer.

Hepatitis C virus negative strand RNA is not detected in peripheral blood mononuclear cells and viral sequences are identical to those in serum: a case against extrahepatic replication

Peripheral blood mononuclear cells (PBMCs) from 27 hepatitis C virus (HCV)-infected patients were analysed for the presence of HCV negative strand RNA with strand-specific Tth-based RT-PCR. No negative strand RNA was detected in any sample, and positive strand HCV sequences amplified from PBMCs were identical to those found in serum. These findings suggest that HCV does not replicate in PBMCs, and the presence of HCV sequences at this site is compatible with passive virus adsorption and/or contamination by circulating virus.

Amplification and fusion of long fragments of hepatitis C virus genome

The 'long PCR' was used for amplification of hepatitis C virus (HCV) subgenomic fragments from liver. After testing several commercially available systems, it was found that Tth as the major enzyme is superior to using Taq. Employing a mixture of Tth and Vent polymerase (rTth polymerase, XL, Perkin Elmer) it was possible to amplify 4.6-kb and 9-kb fragments from biological samples containing as little as 10(2) and 10(4) viral copies, respectively. It was also demonstrated that 'long PCR' is useful for joining together large size amplification products.

Head-to-tail primer tandem repeats generated in hemi-nested PCR

Evidence that hemi-nested PCR protocols are prone to the development of artifacts consisting of multiple head-to-tail primer tandem repeats is presented. This phenomenon was more pronounced with the addition of a large amount of template into the second round PCR and was limited to the primer used in both first and second reactions.

Calcium homeostasis of isolated single cortical fibers of rat lens

PURPOSE

To investigate the calcium homeostasis in single fiber cells isolated from rat ocular lens cortex and to quantify the changes in the concentration of free intracellular calcium [Ca2+]i during the process of disintegrative globulization.

METHODS

Individual fiber cells from the cortex of the adult rat lens were isolated by treatment with trypsin in ion-free buffered sucrose. The isolated fiber cells were loaded with the acetoxymethyl esters of Fluo-3 or Calcium Green-2, or with Fluo-3 and Fura Red, and changes in [Ca2+]i of single cortical fibers were measured using a microfluorometer. The time course of increase of [Ca2+]i in fiber cells exposed to Ringer's solution was measured, and the effects on the increase of [Ca2+]i of calcium channel blocker, verapamil, Na-Ca exchange inhibitors Ni2+ and Zn2+, and protease inhibitor, leupeptin, Na+-free and K+-free media and Ca2+-containing isotonic sucrose solution, were investigated.

RESULTS

In Hepes sucrose solution (containing approximately 1.5 microM Ca2+), the isolated fiber cells maintained stable values of [Ca2+]i at 99.6+/-10 nM (n = 32). Exposure of the isolated fibers to Ringer's solution (containing 2 mM Ca2+) led to a monoexponential increase of [Ca2+]i at a rate of 0.12 min(-1). This increase in [Ca2+]i was accompanied by disintegration of the isolated fibers into discrete but resealed globules. Changes in [Ca2+]i, monitored by using a two-dye ratiometric method using Fura Red and fluo-3, showed a progressive increase in [Ca2+]i in fibers exposed to Ringer's solution, preceding globulization. The [Ca2+]i in the globules in Ringer's solution, determined using Calcium Green-2, was 3.6+/-0.7 microM (n = 23). Compared with that in fibers in Ringer's solution, the rate of increase of [Ca2+]i in fibers was much slower in the presence of 50 microM verapamil (0.047 min[-1]), in Na+-free (0.086 min[-1]) and in K+-free (0.062 min[-1]) Ringer's solution, or when the fibers were suspended in Hepes-sucrose solution, containing 2 mM Ca2+ (0.046 min[-1]). After 30 minutes, the [Ca2+]i of fiber cells exposed to Ringer's solution, containing 2 mM Ni2+ (574.7+/-29 nM; n = 7) or Zn2+ (402.6+/-77 nM; n = 7) was significantly lower (P < 0.001) compared with that in fiber cells exposed to Ringer's solution alone (1995+/-461 nM, n = 10). In Ringer's solution, leupeptin delayed globulization without significantly affecting the increase in [Ca2+]i. The [Ca2+]i of fiber cells isolated from outer and inner cortex and suspended in Hepes-sucrose was comparable; however, after 15 minutes of exposure to Ringer's solution, [Ca2+]i in fibers from the outer cortex was approximately three times higher than [Ca2+]i in those from the inner cortex.

CONCLUSIONS

Exposure to high (millimolar) concentrations of calcium in the external medium leads to an increase in [Ca2+]i of isolated individual fiber cells, which precedes disintegrative globulization. The protective effects of Na+-free and K+-free solutions on globulization appear to be due to a lower rate of increase of [Ca2+]i. Part of the calcium influx may be mediated by L-type calcium channels and by Na-Ca exchange, operating in reverse. Proteolytic inhibitors do not affect the increase in [Ca2+]i but delay globulization by inhibiting calcium-mediated proteolysis. The isolated fiber cells and the disintegrated globules maintain a 100- to 300-fold gradient of calcium across their plasma membranes.

Lack of evidence for hepatitis G virus replication in the livers of patients coinfected with hepatitis C and G viruses

The pathogenic implications of hepatitis G virus (HGV) infection are still unclear. We searched for the presence of HGV RNA and HCV RNA sequences in liver and serum samples from 10 patients with chronic liver disease, 9 of whom were coinfected with HCV. All livers were negative for the presence of the HGV RNA minus strand and only six were positive for the presence of the positive strand, albeit at low levels. In striking contrast, the HCV RNA positive strand was detectable in the liver samples from all nine HCV-positive patients in titers ranging from 10(2) to 10(8) genomic eq/microg of RNA, and the negative HCV RNA strand was present in all but two of these patients. However, the positive-strand RNA titers in serum for the two viruses had similar ranges. These findings imply that the liver is not the primary replication site for HGV, at least in the population of HCV/HGV-coinfected patients. Absence of replication in liver tissue may explain the reported lack of influence of HGV coinfection on the course of chronic hepatitis C.

Hepatitis G virus coinfection in hepatitis C virus-infected liver transplant recipients

BACKGROUND

In this study, we determined the prevalence of hepatitis G virus (HGV) infection in end-stage hepatitis C virus (HCV)-related liver disease and examined the influence of HGV coinfection on the outcome of liver transplantation.

METHODS

HGV was detected by reverse transcriptase-polymerase chain reaction and Southern blotting in sera drawn from 159 patients who were known to be HCV infected before transplantation. Patients were followed up for a mean of 28.4 months after transplantation.

RESULTS

Forty-one (25.3%) patients were HGV positive and the prevalence of HGV infection was similar for different HCV genotypes. Both HGV-positive and -negative groups had similar survival, recurrence rates, inflammatory activity scores, and degree of fibrosis at the time of recurrence.

CONCLUSION

Infection with HGV is common in end-stage HCV-infected patients presenting for liver transplantation. It influences neither the outcome of liver transplantation nor the recurrence of hepatitis in the graft.

Contribution of osmotic changes to disintegrative globulization of single cortical fibers isolated from rat lens

In this study the contribution of osmotic changes to disintegrative globulization of lens cortical fibers was examined. Single fiber cells were isolated by trypsinization of adult rat lens cortex, and morphological changes elicited by exposure to different external solutions were monitored optically. The survival of the fiber-shaped cells was analysed in accordance with the Weibull distribution. Changes in [Ca2+]i were measured using the fluorescent calcium-sensitive dye-Fluo-3. Exposure of isolated fiber cells to Ringer's solution (containing 2 mm Ca2+) led to an exponential increase in [Ca2+]i with a time constant of 10.2+/-0.8 min, and caused disintegrative globulization in 25+/-4 min (=Tg). The process of globulization as well as the rate of increase in [Ca2+]i was delayed by removing Cl- ions from the external media. Globulization was also delayed by adding 20% bovine serum albumin (Tg=107+/-3 min) or chloride channel inhibitors 5, nitro-2-(3-phenylpropylamino) benzoate (NPPB), dideoxyforskolin, niflumic acid, and tamoxifen. When the fiber cells were suspended in isotonic (280 mm sucrose) HEPES-sucrose (HS) or HEPES-EDTA-sucrose (HES) solution, no globulization was observed for an observation time of 120 min. However, exposure to hypotonic (180 mm) HES solution led to disintegration of fiber cells in 75+/-7 min. Disintegration of the fiber induced by hypotonic HES solution could be delayed by either 0. 05 mm leupeptin (Tg=97+/-6 min) or by pre-loading the fibers with BAPTA (Tg=100+/-4 min). Inhibition of membrane calcium transport by 0.5 mm La3+ had no effect on Tg in hypotonic HES. Addition of 2 mm Ca2+ to HES solution accelerated globulization, and Tg was 57+/-4, 69+/-5 and 102+/-6 min for hypo-, iso- and hyper- tonic solutions, respectively. Transient exposure to calcium also accelerated disintegrative globulization of fiber cells exposed subsequently to HES solution. These results suggest that in ionic media, part of the calcium influx in isolated fiber cells is mediated by the influx of chloride ions. In the absence of other ions, the fiber cells still accumulate calcium, although this calcium influx was independent of medium tonicity. Globulization-induced by hypotonic sucrose solution appears to be mediated by the activation of intracellular proteases and by cell swelling-induced release of calcium from internal stores. Such swelling-mediated disintegrative globulization of fiber cells may be of significance in understanding the cellular basis of diabetic cataracts.

Identification of mutations at DNA topoisomerase I responsible for camptothecin resistance

A camptothecin-resistant cell line that exhibits more than 600-fold resistance to camptothecin, designated CPT(R)-2000, was established from mutagen-treated A2780 ovarian cancer cells. CPT(R)-2000 cells also exhibit 3-fold resistance to a DNA minor groove-binding ligand Ho33342, a different class of mammalian DNA topoisomerase I inhibitors. However, CPT(R)-2000 cells exhibit no cross-resistance toward drugs such as Adriamycin, amsacrine, vinblastine, and 4'-dimethyl-epipodophyllotoxin. The mRNA, protein levels, and enzyme-specific activity of DNA topoisomerase I are relatively the same in parental and CPT(R)-2000 cells. However, unlike the DNA topoisomerase I activity of parental cells, which can be inhibited by camptothecin, that of CPT(R)-2000 cells cannot. In addition, parental cells after camptothecin treatment results in a decrease in the level of DNA topoisomerase I, whereas CPT(R)-2000 cells are insensitive to camptothecin treatment. These results suggested that the mechanism of camptothecin resistance is most likely due to a DNA topoisomerase I structural mutation. This notion is supported by DNA sequencing results confirming that DNA topoisomerase I of CPT(R)-2000 is mutated at amino acid residues Gly717 to Val and Thr729 to Ile. We also used the yeast system to examine the mutation(s) responsible for camptothecin resistance. Our results show that each single amino acid change results in partial resistance, and the double mutation gives a synergetic effect on camptothecin resistance. Because both mutation sites are near the catalytic active center, this observation raises the possibility that camptothecin may act at the vicinity of the catalytic active site of the enzyme-camptothecin-DNA complex.

Comparison of hepatitis B virus core promoter sequences in peripheral blood mononuclear cells and serum from patients with hepatitis B

It has been reported that hepatitis B virus (HBV) DNA is present in peripheral blood mononuclear cells (PBMCs), although it is unclear whether it actually replicates there or is adsorbed from serum. HBV DNA sequences from the core promoter and precore regions were amplified from PBMCs and serum taken from 13 patients with hepatitis B infection. Analysis by single strand conformation polymorphism, direct sequencing and cloning revealed identical HBV DNA sequences in both PBMCs and serum from five patients with acute hepatitis and in five out of eight patients with chronic hepatitis. However, in the remaining three chronic hepatitis cases, HBV DNA sequences in both PBMCs and serum were different: two patients harboured HBV DNA sequences from their PBMCs with deletions/insertions in the core promoter region and one patient harboured HBV DNA sequences from their PBMCs with two nucleotide substitutions. These findings point to a possible presence of independent HBV DNA replication in PBMCs.

Alterations in the light transmission through single lens fibers during calcium-mediated disintegrative globulization

PURPOSE

The purpose of this study was to examine changes in the light transmission through single cortical fibers isolated from the rat lens during the process of disintegrative globulization.

METHODS

Single cortical fibers were isolated from adult rat lens by treatment with trypsin in a solution containing 10 mM HEPES, 10 mM EDTA, and 280 mM sucrose (pH 7.4, 300 to 310 mOsm) HEPES-EDTA-sucrose (HES) solution. The isolated fibers were illuminated by a white light source, and the light transmission through the fibers was collected by a charge-coupled device camera and quantified by digital image analysis. In some experiments, thin sections of fixed lens cells were examined using transmission electron microscopy.

RESULTS

Enzymatic dissociation of the lens yielded elongated fibers, which, in the presence of Ringer's solution (containing 2 mM Ca2+), underwent disintegrative globulization. Measurements of light transmission through elongated fibers suspended in HES solution showed maximal transmission at the center of the fiber. Exposure of the cortical fibers to Ringer's solution led to biphasic changes in the intensity of the transmitted light. Within 5 to 10 minutes of exposure to Ringer's solution, a general decrease in the light transmission across the long axis of the fiber was observed. Extended superfusion led to a local, apparent increase in light transmission corresponding to the formation of membrane blebs and globules. Images of disingerated globules focused above their equator showed bright halos with dark central zones. In electron micrographs, the single fibers showed uniform electron density. No significant inhomogeneities or precipitation of intracellular crystallins was observed in globules generated from fiber cells exposed to Ringer's solution; in addition, no high molecular weight protein aggregates were found in the globules.

CONCLUSIONS

Exposure to calcium alters the light-transmitting properties of isolated cortical fibers. The initial decrease in the average light transmittance of the fiber appears to be secondary to cell swelling and may relate to protein-based opacification. An apparent increase in light transmission through calcium-generated globules is likely because of the Becke line generated by a mismatch between the refractive index of the medium and the globule cytoplasm and accentuated by the transition from rod-shaped to spheroidal morphology.