Convenient test for screening metallo-beta-lactamase-producing gram-negative bacteria by using thiol compounds

A simple disk diffusion test was constructed for detection of IMP-1-type metallo-beta-lactamase-producing gram-negative bacteria. Two Kirby-Bauer disks containing ceftazidime (CAZ) and a filter disk containing a metallo-beta-lactamase inhibitor were used in this test. Several IMP-1 inhibitors such as thiol compounds including 2-mercaptopropionic acid, heavy metal salts, and EDTA were evaluated for this test. Two CAZ disks were placed on a Mueller-Hinton agar plate on which a bacterial suspension was spread according to the method recommended by the National Committee for Clinical Laboratory Standards. The distance between the disks was kept to about 4 to 5 cm, and a filter disk containing a metallo-beta-lactamase inhibitor was placed near one of the CAZ disks within a center-to-center distance of 1.0 to 2.5 cm. For IMP-1-producing strains, the growth-inhibitory zone between the two disks expanded, while no evident change in the shape of the growth-inhibitory zone was observed for CAZ-resistant strains producing serine beta-lactamases such as AmpC or SHV-12. As a result, 2 to 3 microliter of undiluted 2-mercaptopropionic acid or mercaptoacetic acid able to block IMP-1 activity gave the most reproducible and clearest results, and CAZ-resistant strains producing AmpC or extended-spectrum beta-lactamases were distinguishable from IMP-1 producers by this test. A similar observation was made with IMP-1-producing clinical isolates such as Serratia marcescens, Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas putida, Acinetobacter spp., and Alcaligenes xylosoxidans. The specificity and sensitivity of this test were comparable to those of PCR analysis using bla(IMP)-specific primers. Therefore, this convenient test would be valuable for daily use in clinical laboratories.

[Epidemiology of drug-resistance and clinical microbiologists in the 21st century]

Many efficacious antimicrobial agents have been developed in the latter half of the 20th century, and this has enabled us to overcome bacterial infections. However, various drug-resistant bacteria including MRSA and VRE have been emerging and these strains will cause serious life-threatening medical problems in the 21st century. Since development of new antimicrobial agents currently stagnates++, promoting the appropriate and prudent use of antimicrobial agents based on EBM is strongly recommended. Thus, establishment of a surveillance system of drug-resistant bacterial infections and their epidemiology as well as further activities by clinical technologists as specialists in medical microbiology will be indispensable in the next century.

[Gene examination methods (detection and genotyping of resistant genes)--metallo-beta-lactamase]

Metallo-beta-lactamases have a hydrolysing activity against various beta-lactams including carbapenems, and beta-lactamase inhibitors such as clavulanic acid and sulbactum. Infections caused by metallo-beta-lactamase producing gram-negative bacteria are becoming a serious problem in Japanese clinical settings despite the recent progress in medical technology. Current screening methods can not distinguish metallo-beta-lactamase producers from those producing AmpC beta-lactamase. Here we show a convenient method of detecting metallo-beta-lactamase producers using a thiol compound(2-mercaptopropionic acid) as well as a PCR method with metallo-beta-lactamase gene specific primers.

[Gene examination methods (detection and genotyping of resistant genes)--multiple-drug-resistant Pseudomonas aeruginosa]

Pseudomonas aeruginosa has been regarded as one of the most stubborn pathogens that easily acquire resistance to various antimicrobial agents. Recently, several clinical isolates that have acquired multiple-resistance to carbapenems, fluoroquinolones, and newly developed aminoglycosides such as amikacin have been reported. Thus, the "drug-resistant P. aeruginosa" was designated as a "class 4 pathogen" in the new "Law Concerning the Prevention of Infectious Diseases and Medical Care for Patients with Infections" in Japan. It is generally considered that no medical facility can escape from severe attack by both multiple-drug resistant gram-positive cocci such as MRSA and gram-negative rods including P. aeruginosa in the 21st century. Therefore, emergency countermeasures should be anticipated to prevent further proliferation of these multiple-drug resistant pathogens.

Biochemical and virological response to interferon therapy in patients with chronic hepatitis C, co-infected with hepatitis G virus

It is still unclear whether hepatitis G virus (HGV) and hepatitis C virus (HCV) co-infection influences the natural course of chronic HCV infection and the response to interferon (IFN) therapy. In this study, we investigated the HGV RNA changes and responses to IFN therapy of HGV RNA-positive hepatitis C patients. The presence of HGV RNA in 264 patients who received IFN therapy at our institute was examined using the nested reverse transcription-polymerase chain reaction with primers deduced from the 5' non-coding region (5'-NCR) of the HGV. We also analysed the nucleotide sequences of the 5'-NCR and HGV before and after IFN therapy. Twelve (4.5%) of the 264 patients with chronic hepatitis C were HGV RNA positive. Of these 12 patients, full information was available in nine. Of those nine, seven became HGV RNA negative during IFN therapy but in six of the seven a relapse occurred. HCV RNA was not detected 1 year after IFN therapy in six patients. The serum alanine aminotransferase (ALT) levels of all the HCV RNA-negative patients post-treatment was within the normal range, irrespective of their HGV RNA status. Nucleotide sequences did not change after IFN therapy in any patient. Hence, we confirm that HGV is sensitive to IFN therapy but the liver damage caused by HGV infection is very mild or does not modify the liver function tests.

Comparison of nerve growth factor mRNA expression in cardiac and skeletal muscle in streptozotocin-induced diabetic mice

To address the role of nerve growth factor (NGF) in diabetes mellitus (DM)-induced cardiac autonomic neuropathy, we quantitated and compared the expression of NGF mRNA in the cardiac and the skeletal muscle in experimental DM mice with the RT-PCR-HPLC method, which we have developed previously, using a NGF deletion mutant RNA as an internal standard. DM was induced in ICR mice via intraperitoneal injection of streptozotocin. RT-PCR was performed using total RNA extracted from left ventricle and soleus muscle, and the levels of NGF mRNA were quantitated by HPLC analysis. NGF mRNA content of the cardiac muscle was 17-fold higher than the skeletal muscles in control mice. NGF mRNA content of the cardiac muscle in diabetic mice at 6 weeks was 4.0-fold higher than that in the control mice, while that of the skeletal muscle in diabetic mice was not different from the controls. These results indicated that the DM-induced increase in NGF mRNA content was higher in cardiac muscle than skeletal muscle, and that NGF might play an important role in cardiac autonomic neuropathy.

Prediction of the development of hepato-cellular-carcinoma in patients with liver cirrhosis by the serial determinations of serum alpha-L-fucosidase activity

OBJECTIVE

Evaluation of the usefulness of the serial determinations of serum alpha-L-fucosidase (AFU) activity for prediction of the development of hepatocellular carcinoma (HCC) was performed.

METHODS AND PATIENTS

Serum AFU activity was determined monthly for 42 months in 73 patients with liver cirrhosis (LC).

RESULTS

HCC was diagnosed in 27 patients by means of ultrasonography during this observation period. In 23 (85%) of the 27 patients, serum AFU activity was found to exceed 700 nmole/ml/h during the LC stage. HCC developed within a few years in 23 (82%) of 28 LC patients with AFU activity exceeding 700 nmole/ml/h, in contrast, it developed in only 4 (9%) of 45 LC patients with AFU activity below 700 nmole/ml/h. AFU activity was already elevated in 23 (85%) of 27 patients at least 6 months before the detection of HCC by ultrasonography.

CONCLUSION

It is conceivable that the development of HCC can be predicted by means of serial determinations of serum AFU activity in patients with LC.

Enhanced theophylline metabolism in patients with bronchial asthma at age 4 and under

The plasma levels of theophylline (TP) and its metabolites were measured in patients with bronchial asthma who were treated with a slow-release preparation of TP. The ratios of the plasma levels of these metabolites to TP levels in the group aged 1-4 years were larger than those in the group aged 5 years and older, suggesting enhanced activity of drug-metabolizing enzymes during infancy.

Crystallization of lipopolysaccharide from a Salmonella typhimurium semi-rough (SR) mutant

Salmonella typhimurium SR-form lipopolysaccharide (LPS), consisting of a single repeating unit of the O-antigenic polysaccharide, linked to the R-core consisting of oligosaccharide that is, in turn, linked to lipid A, formed crystals whose shapes were hexagonal plates, discoids, and solid columns when precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and kept in 70% ethanol containing 250 mm MgCl2 at 4 C for 10 days. Among these crystals, the basic form is considered to be the hexagonal plates. Analyses of hexagonal plate crystals showed that they consist of hexagonal lattices with a lattice constant (a axis) of 4.62 A and longitudinal axis (c axis) of approximately 100 A. In X-ray diffraction patterns in the low-angle region, crystals of S. typhimurium SR-form LPS exhibited much less distinct reflections when compared with crystals of synthetic Escherichia coli-type lipid A. In contrast to the previous finding that S. minnesota S-form LPS possessing the O-antigenic polysaccharide does not crystallize under the same experimental conditions as used in the present study, the presence of a single repeating unit of the O-antigenic polysaccharide does not inhibit crystallization.

Role of multiple efflux pumps in Escherichia coli in indole expulsion

Escherichia coli chromosome encodes several multidrug transporters. Despite their protective function against antibacterial agents, the specific physiological actions of these transporters are not fully understood. E. coli produces indole, a metabolite of tryptophan, under physiological conditions. Defined inactivation of the acrEF gene, the product of which is known as an energy-dependent multiple drug efflux pump, decreased indole excretion while reintroduction of the acrEF gene restored it. A DeltaacrEF mutant accumulated more intracellular indole than the parent. This mutant was more susceptible to the growth-inhibitory effect of indole than the parent. These results indicate that the AcrEF system plays a significant role in indole efflux.

Hepatitis C virus and hepatocarcinogenesis

Although human hepatocellular carcinoma (HCC) is one of the most common types of tumors in the world, the molecular mechanisms underlying hepatitis-C-related human hepatocarcinogenesis are still not clear. HCC is accompanied by virus infections in most cases, and it is suggested that hepatitis B virus and hepatitis C virus (HCV) significantly influence the oncogenic process. The persistence of inflammation following HCV infection is reportedly related to carcinogenesis, and the mechanism of chronic inflammation has been approached by taking viral, immunologic, cytokine and apoptotic responses into consideration. With the progress made in molecular biology, the functional abnormality of oncogenes/tumor suppressor genes has been identified and, apart from the p53 gene, involvement of the IGF-II gene has also been described recently. Furthermore, it has been suggested that uncontrolled proliferation of cancer cells might be based on abnormal regulation of intracellular signal transduction pathways. Here we review the cutting edge of molecular hepatitis C virology in terms of virus-cell interactions, which may contribute to the development of human HCCs. We also discuss the recent progress made in the molecular and cell biology of human hepatocarcinogenesis.

Correlations between in vitro affinity of antipsychotics to various central neurotransmitter receptors and clinical incidence of their adverse drug reactions

OBJECTIVE

This study was performed to determine whether in vitro affinities of currently available antipsychotics toward dopamine or other neuronal receptor systems are associated with their in vivo incidence of central and peripheral adverse drug reactions (ADRs).

METHODS

For 17 antipsychotic drugs available in Japan, the clinical incidences of 7 different types of drug-induced ADRs (i.e., akathisia, dyskinesia, tremor, rigidity, drowsiness, hypotension and dry mouth) were obtained from both post-marketing ADR databases and the investigational clinical trials of eight pharmaceutical companies. Affinity constants (K(i)) of the respective drugs toward dopamine D(1) and D(2) receptors, alpha(1)-adrenoceptors, histamine H(1) receptors, serotonin 5-HT(2) receptors and muscarinic cholinoceptors, determined using rat brain synaptosomes, were obtained from the literature. Relationships between in vitro receptor-binding properties and in vivo incidences of the respective types of antipsychotic-related ADRs were analyzed using Spearman's rank correlation.

RESULTS

Significant (P < 0.05) correlations were observed between the K(i) values for dopamine D(2) receptor and the clinical incidences of akathisia and dyskinesia (r(s) = -0.68 and -0. 66, respectively). Significant (P < 0.05) correlations were also observed between the K(i) values for alpha(1)-adrenoceptor and histamine H(1) receptor and the incidence of drowsiness (r(s)=-0.65 and -0.55, respectively), and between the K(i) values for three receptor systems (i.e., dopamine D(1) receptor, alpha(1)-adrenoceptor and histamine H(1) receptor) and the incidence of dry mouth (r(s) = -0.50, -0.81 and -0.62, respectively).

CONCLUSION

Preclinical receptor-binding data of antipsychotic drugs toward central dopamine and other ancillary neurotransmitter systems may be useful for predicting not only in vivo antipsychotic potency but also clinical incidence of akathisia and dyskinesia for this class of agents. Newly developed antipsychotic drugs with more potent and selective antagonistic activity against the dopamine D(2) receptor may not necessarily be associated with a lower incidence of extrapyramidal ADRs.

Epidemiology of hepatitis B, C, E, and G virus infections and molecular analysis of hepatitis G virus isolates in Bolivia

Prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis G virus (HGV), and hepatitis E virus (HEV) was investigated among 574 healthy blood donors in Bolivia. HCV RNA and HGV RNA in the serum were identified by a nested reverse transcription-PCR using primers derived from the 5' untranslated region (5' UTR). We also tested for hepatitis B surface antigen (HBsAg) and for the antibody to HEV. The results revealed that HGV RNA was present in 84 of 574 (14.6%) tested blood donors, whereas HBsAg was detected in only 2 (0.3%) donors, and no individuals positive for HCV RNA were found. Anti-HEV immunoglobulin G (IgG) was detected in 93 (16.2%) individuals and anti-HEV IgM was found in 10 (1.7%) individuals among the same population. Phylogenetic analysis of 44 HGV isolates in the 5' UTR showed that 27 (61%) isolates were genotype 3 (Asian type) and the remaining 17 (39%) isolates were genotype 2 (United States and European type). Moreover, we obtained a full-length nucleotide sequence of the HGV genome (designated HGV-BL230) recovered from a Bolivian blood donor. The BL230 was composed of 9,227 nucleotides and had a single open reading frame, encoding 2,842 amino acid residues. Interestingly, the BL230 belonged to genotype 2 of HGV at the level of a full-length sequence, although this was classified as genotype 3 by a phylogenetic analysis based on the 5' UTR sequence. The BL230 differed from previously reported HGV/hepatitis GB virus type C isolates by 12 to 13% of the nucleotide sequence and 4% of the amino acid sequence. Our data indicate a high prevalence of HGV in native Bolivians, and the major genotype of HGV was type 3.

Room temperature lasing at blue wavelengths in gallium nitride microcavities

Lasing action has been demonstrated at blue wavelengths in vertical cavity surface-emitting lasers at room temperature. The microcavity was formed by sandwiching indium gallium nitride multiple quantum wells between nitride-based and oxide-based quarter-wave reflectors. Lasing action was observed at a wavelength of 399 nanometers under optical excitation and confirmed by a narrowing of the linewidth in the emission spectra from 0.8 nanometer below threshold to less than 0.1 nanometer (resolution limit) above threshold. The result suggests that practical blue vertical cavity surface-emitting lasers can be realized in gallium-nitride-based material systems.

[Self-expanding stent (Wallstent) supported angioplasty for carotid artery stenosis]

We reported the preliminary results of percutaneous transluminal angioplasty (PTA) supported with a self-expanding stent (Wallstent) for the cervical internal carotid artery (i.c.) stenosis in 6 patients (7 lesions). All were male aged from 60 to 79 (mean 70.8). Three patients were symptomatic and 3 were asymptomatic. The procedure was attempted in patients with severe i.c. stenosis according to criteria of NASCET, ECST or ACAS studies and with high risk if carotid endarterectomy (CEA) were performed. In all cases, vascular access was from the femoral artery and angioplasty was performed without cerebral protection. Successful angioplasty was obtained in all cases with no mortality. Stenosis was improved from 82.7% (74-90%) to 17.4% (10-33%). Perioperative complications were seen in only one case with TIA during the postdilatation period, which was supposed to be due to a distal embolism. The preliminary results of PTA supported with self-expanding stent for severe i.c. stenosis were excellent. These results suggested that some patients with severe i.c. stenosis can be treated safely and effectively by stent-supported PTA. However, it is necessary to mark the indications clear and strict, and to follow up these lesions after the procedure, because of the possibility of perioperative ischemic complications and restenosis.

Interferon therapy reduces the risk for hepatocellular carcinoma: national surveillance program of cirrhotic and noncirrhotic patients with chronic hepatitis C in Japan. IHIT Study Group. Inhibition of Hepatocarcinogenesis by Interferon Therapy

BACKGROUND

Previous studies on the effect of interferon therapy on the incidence of hepatocellular carcinoma have not sufficiently assessed degree of liver fibrosis, a major risk factor for hepatocellular carcinoma.

OBJECTIVE

To evaluate the effect of interferon therapy on incidence of hepatocellular carcinoma, adjusting for risk factors, including the degree of liver fibrosis.

DESIGN

Retrospective cohort study.

SETTING

Seven university hospitals and one regional core hospital in Japan.

PATIENTS

2890 patients with chronic hepatitis C who had undergone liver biopsy since 1986. Of these patients, 2400 received interferon and 490 were untreated.

MEASUREMENTS

The degree of liver fibrosis was assessed from stage F0 (no fibrosis) to stage F4 (cirrhosis). Response to interferon was determined virologically and biochemically. Screening for development of hepatocellular carcinoma was performed periodically during an average follow-up of 4.3 years. Effect of interferon therapy on the risk for hepatocellular carcinoma was analyzed by using Cox proportional hazards regression.

RESULTS

Hepatocellular carcinoma developed in 89 interferon-treated patients and in 59 untreated patients. Among untreated patients, the annual incidence of hepatocellular carcinoma increased with the degree of liver fibrosis, from 0.5% among patients with stage F0 or F1 fibrosis to 7.9% among patients with stage F4 fibrosis. The cumulative incidence in treated and untreated patients differed significantly for patients with stage F2 fibrosis (P = 0.0128) and for those with stage F3 fibrosis (P = 0.0011). In multivariate analysis, interferon therapy was associated with a reduced risk for hepatocellular carcinoma (adjusted risk ratio, 0.516 [95% CI, 0.358 to 0.742]; P < 0.001), especially among patients with sustained virologic response (risk ratio, 0.197 [CI, 0.099 to 0.392]), among those with persistently normal serum alanine aminotransferase levels (risk ratio, 0.197 [CI, 0.104 to 0.375]), and among those with alanine aminotransferase levels less than two times the upper limit of normal (risk ratio, 0.358 [CI, 0.206 to 0.622]).

CONCLUSIONS

Interferon therapy significantly reducesthe risk for hepatocellular carcinoma, especially among virologic or biochemical responders.