[Rapid detection of the hemolysin genes in Aeromonas sobria by the polymerase chain reaction]

The hemolysin of Aeromonas sobria is one of the important virulence factors in this organism. Rapid detection and identification test for A. sobria is important for early and specific diagnosis of this infectious disease. We evaluated the polymerase chain reaction (PCR) for the rapid detection of A. sobria. Two pairs of synthetic oligonucleotide primers (ASA1-s and a; AerAAS-s and a) were used in PCR technique to detect the different hemolysin genes (ASA1 and aerAAS) in A. sobria. The PCR identified 91% of ASA1-positive and 23.4% of aerAAS-positive strains in beta-hemolytic A. sobria. Other species of Aeromonas, Plesiomonas shigelloides, Vibrio cholerae O1 and V. parahaemolyticus tested were negative in the PCR with two pairs of primers. The PCR technique for detection of two hemolysin genes suggested the possibility of application of this method for detection of A. sobria in A. sobria-associated infections.

Doppler estimation of pulmonary artery end-diastolic pressure using contrast enhancement of pulmonary regurgitant signals

Pulmonary artery (PA) end-diastolic pressure is used as an estimate of PA wedge pressure. We evaluated contrast enhanced pulmonary regurgitant signals in the assessment of PA end-diastolic pressure in 24 patients in a critical care unit. Right atrial pressure was estimated by the percent decrease of the inferior vena caval diameter with inspiration. Weak or absent pulmonary regurgitant signals were enhanced by sonicated albumin (Albunex) in 23 patients (96%). The Doppler-determined PA end-diastolic pressure (the sum of the pulmonary regurgitant pressure gradient at end-diastole and the right atrial pressure) was significantly correlated with the catheter-determined PA end-diastolic pressure (y = 0.85x + 1.72, r = 0.93). Compared with invasive hemodynamic monitoring, the contrast-enhanced Doppler technique using Albunex is effective for measuring PA end-diastolic pressure, even in critically ill patients.

Isolation and characterization of restriction endonuclease in Plesiomonas shigelloides and Aeromonas species

Five restriction endonucleases (ENases) and one ENase were found in a screen of 196 strains of Plesiomonas shigelloides and 147 strains of Aeromonas species. Plesiomonas and Aeromonas species are classified as Vibrionaceae, identified as food-poisoning bacteria, are closely genetically related to each other, and their ENases producing abilities have not bee reported. ENases were detected at relatively low frequencies in these species as compared to those in other species, such as Salmonella species and Vibrio parahaemolyticus. All Enases were shown to be isoschizomers of already known ENases. One of the Plesiomonas ENases, designated PshBI, recognizing the sequence 5'-AT/TAAT-3' should be useful, since PshBI ENase is produced at a high yield of 7000 units/g of wet cells. The specificities of other ENases are also described in this paper.

Infectivities of human and other primate lentiviruses are activated by desialylation of the virion surface

The envelope protein, gp120, of human immunodeficiency virus type 1 (HIV-1) is heavily glycosylated and sialylated. The heavy sialylation greatly affects the physical properties of the protein, as it resolves into a wide acidic pH range despite the basic pI value predicted for its polypeptide backbone (B. S. Stein and E. G. Engleman, J. Biol. Chem. 265:2640-2649, 1990). However, the functional significance of the heavy sialylation remains elusive. Here, we show that desialylation of HIV-1 with neuraminidase greatly augments the initial virus-cell interaction, leading to remarkably enhanced viral replication and cytopathogenicity. This enhancement appeared to be a direct result of the removal of negatively charged sialic acids but not of the exposure of galactose residues or complement activation. Complementing these results, studies with inhibitors of mannosidase I and mannosidase II showed that the processing of HIV-1 oligosaccharides into the complex type to acquire the terminal sialic acid residues impeded the full replication capacity of the virus and that its prevention also enhanced virus replication and cytopathogenicity. Enhancement of infection by desialylation was found widely, with HIV-1 laboratory strains of different cell tropisms and primary isolates as well as HIV-2 and simian immunodeficiency virus. Thus, the sialylation catalyzed by host cell pathways appeared to reduce the infectivity of human and nonhuman primate lentiviruses. Our results further suggested that desialylation would help increase the titers of HIV-based vectors.

Sucralfate and Helicobacter pylori

Sucralfate enhances the eradication rate of Helicobacter pylori when administered with antibiotics. Sucralfate acts on H. pylori through mucus gel. Whether sucralfate exerts its anti-ulcer action through the eradication of H. pylori is still controversial. As sucralfate itself is an effective, well-tolerated and cost-effective anti-ulcer agent, its mechanisms of action should be investigated further.

Effects of erythromycin and roxithromycin on oxidation of testosterone and nifedipine catalyzed by CYP3A4 in human liver microsomes

Roxithromycin and erythromycin were incubated with rat and human liver microsomal or reconstituted cytochrome P450 (P450 or CYP) monooxygenase systems in the presence of an NADPH-generating system, and the effects of these chemicals on testosterone 6 beta-hydroxylation and nifedipine oxidation activities were compared with those of typical CYP3A4 inhibitors including ketoconazole, troleandomycin, and gestodene. Roxithromycin and erythromycin were found to be relatively weak inhibitors of testosterone 6 beta-hydroxylation and nifedipine oxidation activities by rat and human liver microsomes or by reconstituted systems containing CYP3A4/5. Formation of an inhibitory P450-metabolite complex was determined spectrally by incubating troleandomycin with human liver microsomes; the extents of the complex formation were lesser in liver microsomes of humans than those of rats treated with dexamethasone. Erythromycin and roxithromycin were also activated slightly by rat liver microsomes to form P450.Fe(II)-metabolite complex, although these chemicals caused very little or undetectable levels, respectively, of spectral changes by human liver microsomes even when a human sample which contained relatively high levels of CYP3A4 was used. These results suggested that roxithromycin and erythromycin were relatively less potent to inhibit CYP3A4-catalytic activities in human liver microsomes, because of their low capabilities to form P450.Fe(II)-metabolite complex.

Lack of electron transfer from cytochrome b5 in stimulation of catalytic activities of cytochrome P450 3A4. Characterization of a reconstituted cytochrome P450 3A4/NADPH-cytochrome P450 reductase system and studies with apo-cytochrome b5

Many catalytic activities of cytochrome P450 (P450) 3A4, the major human liver P450 enzyme, require cytochrome b5 (b5) for optimal rates. The stimulatory effect of b5 on P450 reactions has generally been thought to be due to transfer of electrons from ferrous b5 to the ferrous P450-O2-substrate complex. We found that apo-b5, devoid of heme, could substitute for b5 in stimulating two prototypic activities, testosterone 6beta hydroxylation and nifedipine oxidation. The stimulatory effect was not seen with albumin, hemoglobin, catalase, or cytochrome c. Apo-b5 could not substitute for b5 in a testosterone 6beta hydroxylation system composed of NADH-b5 reductase and P450 3A4. Rates of electron transfer from NADPH-P450 reductase to ferric P450 3A4 were too slow (<2 min-1) to support testosterone 6beta hydroxylation ( approximately 14 min-1) unless b5 or apo-b5 was present, when rates of approximately 700 min-1 were measured. The oxidation-reduction potential (Em,7) of the ferric/ferrous couple of P450 3A4 was unchanged ( approximately -310 mV) under different conditions in which the kinetics of reduction were altered by the addition of substrate and/or apo-b5. Rapid reduction of P450 3A4 required substrate and a preformed complex of P450 3A4, NADPH-P450 reductase, and b5; the rates of binding of the proteins to each other were 2-3 orders of magnitude less than reduction rates. We conclude that b5 can facilitate some P450 3A4-catalyzed oxidations by complexing with P450 3A4 and enhancing its reduction by NADPH-P450 reductase, without directly transferring electrons to P450.

Effects of roxithromycin, erythromycin and troleandomycin on their N-demethylation by rat and human cytochrome P450 enzymes

1. The effects of treatment of rat with roxithromycin, erythromycin and troleandomycin as well as other chemicals including typical cytochrome P450 inducers were examined in rat and human liver microsomes. 2. Erythromycin and troleandomycin but not roxithromycin caused slight increases in CYP3A1 levels and the N-demethylation of roxithromycin, erythromycin and troleandomycin and oxidation of nifedipine in rat, but none of these chemicals induced significantly CYP2B1 levels or benzphetamine N-demethylation activities. 3. Dexamethasone and pregnenolone 16 alpha-carbonitrile induced CYP3A1 levels and N-demethylation of roxithromycin, erythromycin and troleandomycin but not of benzphetamine, in rat liver microsomes. Treatment of rat with phenobarbital caused increases in both CYP2B1 and 3A1 levels and all of the N-demethylation activities examined. Phenytoin and metyrapone produced increases in contents of 2B1 and activities of benzphetamine N-demethylation as well as of roxithromycin, erythromycin and troleandomycin, although these two inducers did not induce 3A1 protein significantly. 4. In man, a liver sample that was high in CYP3A4 and nifedipine oxidation activity was found to be the most active in N-demethylation activities towards these substrates examined. In addition, recombinant 3A4 catalysed very efficiently the N-demethylation of roxithromycin, erythromycin and troleandomycin in reconstituted monooxygenase systems. 5. These data suggest that erythromycin and troleandomycin, but not roxithromycin, were able to induce CYP3A1 in rat liver microsomes, and that N-demethylation of roxithromycin, erythromycin and troleandomycin were catalysed mainly by 3A1 (and partly by 2B1) in rat and by 3A4 in man.

Determination of thallium in soils by flame atomic absorption spectrometry

A method is described for the determination of Tl in soils by FAAS, involving extraction of Tl from 5 g of soil by digestion with HClO(4)/HNO(3) followed by separation of the extracted Tl into 5 mL of diisopropylether from HBr solution, including Ce(SO(4))(2). Tl in the organic phase is determined by direct aspiration into the spectrophotometer. The percentage relative standard deviation (% RSD) for 5 replicate samples is about 1%. The detection limits (S/N = 3) of this method are 0.001 mg/L for aqueous solution and 0.02 mg/kg DW for soil, when 50 mL of soil solution corresponding to 2.5 g soil are used. The Tl concentration even of unpolluted soils can be determined. The method was shown to be unaffected by the presence of various ions in soil and was able to recover nearly 100% Tl added to soils. The arithmetic mean (range) of 18 Japanese unpolluted surface soils was 0.33 (0.10-0.56)mgTl/kg DW.

In vivo and in vitro characterization of CYP2E1 activity in Japanese and Caucasians

Chlorzoxazone's disposition after oral administration was determined in 20 young healthy Caucasian men and a similar group of Japanese men. The drug's plasma concentrations were significantly higher and its rate of elimination slower in Japanese compared to Caucasian men. Accordingly, chlorzoxazone's oral clearance was smaller (40%) in Japanese men and a similar difference (30%) was still apparent after normalizing for body weight (3.74 +/- 1.23 versus 5.05 +/- 1.41 ml.min-1.kg-1, P < .05). This slower elimination was associated with a reduced (fractional) clearance by 6-hydroxylation (2.34 +/- 1.04 ml.min-1.kg-1 versus 3.23 +/- 1.10, P < .05). Because such metabolism is mediated by cytochrome P4502E1 (CYP2E1), these findings suggest a lower level of the enzyme's catalytic activity in Japanese men. This was confirmed by in vitro studies with microsomes prepared from livers of individuals representative of the two racial groups. CYP2E1 levels were lower (61% P < .002) and CYP2E1-mediated chlorzoxazone 6-hydroxylase (22%, P < .001) and aniline 4-hydroylase (35%, P < .0001) activities were reduced in Japanese preparations compared to those from Caucasians. No relationships were found between measures of CYP2E1 activity, both in vivo and in vitro, and genomic polymorphisms in the CYP2E1 gene identified by Rsal/Pstl and Dral restriction fragment length polymorphisms. Collectively, these data show an interracial difference in CYP2E1 activity. Because this enzyme is importantly involved in the activation of environmental procarcinogens, such a difference may account, in part, for the lower rate of some cancers, e.g., lung cancer, in Japanese compared to Caucasians men.

The production of arthritis in beagles by an immunological reaction to bovine serum albumin

Arthritis was produced in beagles by the immunological reaction to bovine serum albumin (BSA). Dogs immunized with BSA showed the development of delayed type-hypersensitivity response to BSA and the significant increase in the titer of serum anti-BSA antibodies. The development of arthritis and the increase in a number of nucleated cells in synovial fluid were observed by the injection with BSA into the knee joints of immunized dogs. The synovial membrane of BSA-injected joints revealed a remarkable villous hyperplasia of membrane, and an infiltration of lymphocytes and plasma cells around vessels, resulting in a lymphoid nodule-like formation. The depositions of IgG and C3 on the surface of the synovial membrane were also observed in BSA-injected joints. Histopathological and immunopathological findings indicated that the immune response to BSA in the knee joints could induce a rheumatoid arthritis like chronic synovitis in dogs.

Ethanol sclerosis can be a safe and useful treatment for pericardial cyst

We report the case of a 41-year-old man with a pericardial cyst treated by percutaneous aspiration and ethanol injection. He was referred to our hospital because of electrocardiographic abnormality. On admission, chest x-ray revealed a large pericardial cyst in the right cardiophrenic angle. The cyst was examined by echocardiography, computed tomography, and cytological analysis of aspiration fluid from the cyst. Ethanol sclerosis was applied for treatment of the cyst, which had continued to increase in size. There was no recurrence of the cyst 6 months after the treatment. Percutaneous ethanol sclerosis can be the first choice of treatment for pericardial cyst.

An N-[(R)-(-)-2-hydroxypropionyl]-alpha-L-perosamine homopolymer constitutes the O polysaccharide chain of the lipopolysaccharide from Vibrio cholerae O144 which has antigenic factor(s) in common with V. cholerae O76

Chemical and serological studies were performed with the lipopolysaccharide (LPS) from Vibrio cholerae O144 (O144). The LPS of O144 contained D-glucose, D-galactose, L-glycero-D-manno-heptose, D-fructose, D-quinovosamine (2-amino-2,6-dideoxy-D-gluco-pyranose) and L-perosamine (4-amino-4,6-dideoxy-L-manno-pyranose). The perosamine, a major component sugar of the LPS from O144, was in an L-configuration, as is also the case in the LPS from V. cholerae O76 (O76), in contrast to the D-configuration of the perosamine in the LPS of V. cholerae O1. A structural analysis revealed that the O polysaccharide chain of the LPS from O144 is an alpha(1-->2)-linked homopolymer of (R)-(-)-2-hydroxypropionyl-L-perosamine. The serological cross-reactivity between O144 and O76 was clearly revealed by cross-agglutination and cross-agglutinin absorption tests with whole cells, as well as by passive hemolysis tests with sheep red-blood cells that had been sensitized with the LPS from O144 and O76. In contrast, in passive hemolysis tests, the LPS of O144 did not cross-react serologically with the LPSs from other strains such as V. cholerae O1 (Ogawa and Inaba), V. cholerae O140, Vibrio bio-serogroup 1875 (Original and Variant) and Yersinia enterocolitica O9. The LPSs from these strains consist of O polysaccharide chains composed of alpha(1-->2)-linked homopolymers of D-perosamine with various N-acyl groups, and they share the Inaba antigen factor C of V. cholerae O1 in common. The results obtained in this study demonstrate that the absolute configuration of the perosamine residue in homopolymers plays a very important role in the expression of the serological specificity of the Inaba antigen factor C of V. cholerae O1.

Temporal shifts in traits of Vibrio cholerae strains isolated from hospitalized patients in Calcutta: a 3-year (1993 to 1995) analysis

This study presents results of a surveillance on cholera conducted with hospitalized patients admitted to the Infectious Diseases Hospital, Calcutta, India, from January 1993 to December 1995. The O139 serogroup of Vibrio cholerae dominated in 1993 but was replaced by O1 as the dominant serogroup in 1994 and 1995. The isolation rate of V. cholerae non-O1 non-O139 did not exceed 4.9% throughout the study period, while the isolation rate of the O139 serogroup in 1994 and 1995 was below 9%. No temporal clustering of any non-O1 non-O139 serogroup was observed. With the exception of 1 strain, none of the 64 strains belonging to the non-O1 non-O139 serogroup hybridized with ctx, zot, and ace gene probes, while 97.3 and 97.7% of the O139 and O1 strains, respectively, hybridized with all the three probes. Multiplex PCR studies revealed that all the O1 strains belonged to the EIT or biotype. There was a progressive increase in the cytotoxic response on CHO and HeLa cells evoked by culture supernatants of strains of V. cholerae non-O1 non-O139 isolated during 1994 and 1995 compared with the response evoked by those isolated in 1993. Dramatic shifts in patterns of resistance to antibiotics between strains of V. cholerae belonging to different serogroups and within strains of a serogroup isolated during different time periods were observed. There was a discernible increase in the incidence of multidrug-resistant strains of V. cholerae O1 isolated in 1994 and 1995 compared with that in 1993. On the basis of the results of this study, we predict the possibility of newer variants of V. cholerae emerging in the future.

A case of chromomycosis with tumor-like growth

A 66-year-old woman who lived on Tokunoshima Island, a small and remote southern island of the Japanese archipelago, had suffered from chromomycosis for more than 30 years and presented with a tumor-like growth on the posterior crural region of his right leg. Fonsecaea pedrosoi was identified as the pathogen from its growth pattern and micromorphological characteristics. The patient was successfully treated with 5-fluorocytosine, itoraconazole, and topical thermotherapy.

hMutSbeta, a heterodimer of hMSH2 and hMSH3, binds to insertion/deletion loops in DNA

In human cells, mismatch recognition is mediated by a heterodimeric complex, hMutSalpha, comprised of two members of the MutS homolog (MSH) family of proteins, hMSH2 and GTBP [1,2]. Correspondingly, tumour-derived cell lines defective in hMSH2 and GTBP have a mutator phenotype [3,4], and extracts prepared from these cells lack mismatch-binding activity [1]. However, although hMSH2 mutant cell lines showed considerable microsatellite instability in tracts of mononucleotide and dinucleotide repeats [4,5], only mononucleotide repeats were somewhat unstable in GTBP mutants [4,6]. These findings, together with data showing that extracts of cells lacking GTBP are partially proficient in the repair of two-nucleotide loops [2], suggested that loop repair can be GTBP-independent. We show here that hMSH2 can also heterodimerize with a third human MSH family member, hMSH3, and that this complex, hMutSbeta, binds loops of one to four extrahelical bases. Our data further suggest that hMSH3 and GTBP are redundant in loop repair, and help explain why only mutations in hMSH2, and not in GTBP or hMSH3, segregate with hereditary non-polyposis colorectal cancer (HNPCC) [7].

New applications of bacterial systems to problems in toxicology

Bacterial systems have long been of use in toxicology. In addition to providing general models of enzymes and paradigms for biochemistry and molecular biology, they have been adapted to practical genotoxicity assays. More recently, bacteria also have been used in the production of mammalian enzymes of relevance to toxicology. Escherichia coli has been used to express cytochrome P450, NADPH-cytochrome P450 reductase, flavin-containing monooxygenase, glutathione S-transferase, quinone reductase, sulfotransferase, N-acetyltransferase, UDP-glucuronosyl transferase, and epoxide hydrolase enzymes from humans and experimental animals. The expressed enzymes have been utilized in a variety of settings, including coupling with bacterial genotoxicity assays. Another approach has involved expression of mammalian enzymes directly in bacteria for use in genotoxicity systems. Particularly with Salmonella typhimurium. Applications include both the reversion mutagenesis assay and a system using a chimera with an SOS-response indicator and a reporter.

The iothalamate clearance in cats with experimentally induced renal failure

Plasma iothalamate (IOT) disappearance rates were measured after a single-injection of IOT (113.8 mg/kg, IV) in cats with experimentally induced renal failure. The disappearance rates especially fitted into the one compartment model. The mean value of plasma disappearance rates of IOT in these cats with induced renal failure (2.16 +/- 0.240 x 10(-3) micrograms/ml/min) was markedly lower than that of clinically healthy cats (4.10 +/- 1.00 x 10(-3) micrograms/ml/min). These results demonstrate that IOT clearance is available for evaluation of renal function in cats.

Factors affecting appearance patterns of hip-flexion contractures and their effects on postural and gait abnormalities

Hip flexion contractures accompanying various orthopedic and neurologic conditions not only limits the physical activities of the patients but also distorts their postures and gait patterns. The purposes of this study were to characterize the appearance patterns of flexion contracture at the hip joints and to elucidate how this disability affects their postural and gait abnormalities. Seventy-eight patients (mean age of 68.1 +/- 10.5 years) with hemiplegia, femoral neck fractures, osteoarthritis of the hip and other conditions causing hip flexion contractures were studied. The presence and degree of hip flexion contracture were estimated in the supine position using the Thomas maneuver with a goniometer. Relationship between appearance patterns and 12-survey variables was also analyzed statistically. As a result, it was revealed that whether lack of mobility caused by hip flexion contracture was compensated for by pelvic tilt an an increase of lumbar lordosis or not was affected by four factors. It was also revealed that whether it appeared unilaterally or bilaterally was affected by five factors. In addition, some postural and gait abnormalities caused by hip flexion contracture were observed in many patients. These results suggest that clinical pictures of the patient's posture and gait abnormality depend on his ability to regulate the position of the trunk and knees as well as the mobility of his spine.

Effects of heart rate on coronary circulation and external mechanical efficiency in elderly hypertensive patients with left ventricular hypertrophy

BACKGROUND AND HYPOTHESIS

Mechanisms of heart failure in elderly hypertensive patients with hypertrophy have not been studied sufficiently. We hypothesized that impaired increment of coronary blood flow in response to increases in heart rate could be responsible for the occurrence or aggravation of heart failure.

METHODS

To test this hypothesis, we measured coronary hemodynamics and lactate balance during basal conditions and atrial pacing in 21 elderly patients aged > or = 65 years (mean 74 +/- 6 years) without coronary arterial disease: 7 normotensive control patients (Group 1), 7 hypertensive hypertrophic patients without a history of congestive heart failure (Group 2), and 7 patients with such history (Group 3). Coronary sinus blood flow (CSBF) was measured in coronary sinus using a thermodilution catheter.

RESULTS

During basal conditions, heart rate did not differ among the three groups (67 +/- 3 in Group 1, 65 +/- 11 in Group 2, and 63 +/- 6 beats/ in Group 3). CSBF was significantly higher in the two hypertrophic groups than in the control group, but CSBF normalized by left ventricular mass was significantly lower in both hypertrophic groups. External mechanical efficiency (EME) obtained as left ventricular work divided by myocardial oxygen consumption did not differ among groups during basal conditions (36 +/- 9% in Group 1, 35 +/- 8% in Group 2, and 29 +/- 9% in Group 3, NS). During atrial pacing to increase heart rate by 25 +/- 5% (lower) and 54 +/- 6% (higher), the increases in CSBF were markedly limited in both hypertrophic groups, and the response in Group 3 was more depressed than that in Group 2. EME did not change in the control group or in Group 2, but did decrease to 21 +/- 5% in Group 3 during the higher pacing rate (p < 0.01 vs. basal conditions). In this group, the relationship between EME and heart rate showed a significant negative correlation (r = -0.56, p = 0.02). Lactate balance in coronary sinus blood showed a tendency to production in Group 3 during the higher pacing rate, suggesting myocardial ischemia.

CONCLUSION

These findings suggest that in hypertensive hypertrophic patients with a history of heart failure, the coronary circulation system is vulnerable to increasing heart rate. In medical treatment of elderly hypertensive patients, control of heart rate in addition to blood pressure control should be considered to minimize the occurrence or aggravation of heart failure.

[Heart conduction system and accessory pathways]

The morphology of atrioventricular (AV) junctions in the heart has been investigated using comparative anatomical analyses. For scanning electron microscopy, tissue blocks are treated with HCl to digest connective tissue elements. In fishes, amphibians and reptiles, there is a muscular system connecting the atrial muscle to the ventricular myocardium. These muscle fibers completely surround the inner surface of the atrioventricular ring and termed "ring muscular tissue", the cells of which are slender and small and vertically oriented. They contain small-sized mitochondria, relatively few myofibrils and variable amounts of glycogen. In mammalian hearts, the AV node and bundle system is the only functional myocardial connection between the atria and ventricles. Architecture and ultrastructure of AV nodal cells are similar to those of AV ring muscular tissue seen in the lower vertebrates. In human hearts, however, the muscle bundles which directly connect the atrium with the ventricle, i.e., accessory conduction pathways, are scarcely encountered. From the developmental- and comparative-anatomical points of view, it is likely that the accessory pathways in man are the remnants of the ring muscular tissue seen in lower vertebrates.

Further studies on biochemical characteristics and serologic properties of the genus Aeromonas

We characterized a collection of 268 Aeromonas isolates from diverse sources (clinical, animal, and environmental sources) for their species and serogroup designations. Overall, 97% of these strains could be identified to the genomospecies level by using an expanded battery of biochemical tests. Members of the Aeromonas hydrophila complex (A. hydrophila, HG2, and A. salmonicida), a group that has previously been difficult to separate biochemically, could easily be distinguished from one another by using a number of recently described phenotypic properties which included utilization of DL-lactate and urocanic acid. Differences in species distributions on the basis of the source of isolation were noted. Serogroup analysis of these 268 isolates plus a number of reference cultures indicated that (i) each genomospecies is serologically heterogeneous and individual serogroups can be found in more than one species, (ii) most type or reference strains for each hybridization group are not serologically representative of the genomospecies at large, (iii) serogroups O:11, O:34, and O:16 predominate clinically (48%), supporting previous studies indicating their importance in human infections, and (iv) most A. trota strains do not express the O139 antigen of Vibrio cholerae. The collective results suggest that both species and serogroup designations are important factors in establishing which isolates can cause human infections when they are acquired from nonclinical sources (foods, animals, and the environment).

Direct enzymatic assay of urinary sulfated bile acids to replace serum bilirubin testing for selective screening of neonatal cholestasis

Direct enzymatic assay of urinary sulfated bile acids is a sensitive, rapid, minimally invasive, and convenient method of detecting cholestasis in young infants. It may replace measurement of serum direct bilirubin for selective screening for biliary atresia and neonatal hepatitis syndrome at 1 month of age.

Requirements for cytochrome b5 in the oxidation of 7-ethoxycoumarin, chlorzoxazone, aniline, and N-nitrosodimethylamine by recombinant cytochrome P450 2E1 and by human liver microsomes

NADH-dependent 7-ethoxycoumarin O-deethylation activities could be reconstituted in systems containing cytochrome b5 (b5), NADH-b5 reductase, and bacterial recombinant P450 2E1 in 100 mM potassium phosphate buffer (pH 7.4) containing a synthetic phospholipid mixture and cholate. Replacement of NADH-b5 reductase with NADPH-P450 reductase yielded a 4-fold increase in 7-ethoxycoumarin O-deethylation activity, and further stimulation (approximately 1.5-fold) could be obtained when NADPH was used as an electron donor. Removal of b5 from the NADH- and NADPH-supported systems caused a 90% loss of 7-ethoxycoumarin O-deethylation activities in the presence of NADPH-P450 reductase, but resulted in complete loss of the activities in the absence of NADPH-P450 reductase. Km values were increased and Vmax values were decreased for 7-ethoxycoumarin O-deethylation when b5 was omitted from the NADPH-supported P450 2E1-reconstituted systems. Requirements for b5 in P450 2E1 systems were also observed in chlorzoxazone 6-hydroxylation, aniline p-hydroxylation, and N-nitrosodimethylamine N-demethylation. In human liver microsomes, NADH-dependent 7-ethoxycoumarin O-deethylation, chlorzoxazone 6-hydroxylation, aniline p-hydroxylation, and N-nitrosodimethylamine N-demethylation activities were found to be about 55, 41, 33, and 50%, respectively, of those catalyzed by NADPH-supported systems. Anti-rat NADPH-P450 reductase immunoglobulin G inhibited 7-ethoxycoumarin O-deethylation activity catalyzed by human liver microsomes more strongly in NADPH- than NADH-supported reactions, while anti-human b5 immunoglobulin G inhibited microsomal activities in both NADH- and NADPH-supported systems to similar extents. These results suggest that b5 is an essential component in P450 2E1-catalyzed oxidations of several substrates used, that about 10% of the activities occur via P450 2E1 reduction by NADPH-P450 reductase in the absence of b5, and that the NADH-supported system contributes, in part, to some reactions catalyzed by P450 2E1 in human liver microsomes.