Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein

Effects of G protein subunits from rat brain on cardiac K⁺ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain subunits preparation could activate the atrial muscarine receptor-gated K⁺ channel (I_K.ACh). Neither the detergent, CHAPS, used to suspend nor the boiled preparation activated I_K.ACh. Furthermore, preincubation of subunits preparation in Mg²⁺-free solution, which easily inactivated -GTP-S, did not affect -activation of I_K.ACh. We concluded, therefore, that subunits themselves can activate I_K.ACh.Supported by the grants from the Ministry of Education, Culture and Science of Japan and from the Calcium Signal Workshop on Cardiovascular Systems     

Susceptibility ofAlcaligenes denitrificans subspeciesxylos-oxydans to beta-lactam antibiotics

The susceptibility of 56 clinical isolates and two reference strains ofAlcaligenes denitrificans subsp.xylosoxydans to -lactam agents was tested and related to -lactamase activity of the strains. The MICs of 12 -lactams determined by an agar dilution method showed that all the strains were sensitive to imipenem and moxalactam. Forty-one cloxacillin-sensitive -lactamase producing strains were highly susceptible to azlocillin, piperacillin and ticarcillin, and less susceptible to several cephalosporins (cefamandole, cefoperazone, ceftazidime). The 17 remaining -lactamase-producing strains, which were sensitive to clavulanic acid and to a lesser extent cloxacillin, had variable resistance to the penicillins tested and synergy was obtained when these penicillins were combined with clavulanic acid or tazobactam. The choice of agents for treatment of infections with this organism must take into account the susceptibility phenotype of clinical isolates.     

Emergence of resistance to beta-lactam agents inPseudomonas aeruginosa with group I beta-lactamases in Spain

The contribution of induction and stable derepression of chromosomal class I -lactamases to -lactam antibiotic resistance was studied in clinical isolates ofPseudomonas aeruginosa collected from patients treated with -lactam antibiotics. Multiple isolates from the same patient were characterized by O-serotyping as a primary screen, combined with pyocin typing. Sonicated extracts of cells were assayed for chromosomal and plasmid-mediated -lactamases by isoelectric focusing and cloxacillin inhibition studies. The specific -lactamase activity, basal and induced, with cefoxitin was determined to differentiate strains with inducible or derepressed production of the enzyme. Beta-lactamase induction was performed in each strain against the -lactam agents used in the therapy of each patient. The observations showed that induction against older penicillins such as penicillin, amoxicillin, and amoxicillin/clavulanate resulted in a moderate to strong increase in -lactamase activity, whereas the results obtained with first-generation cephalosporins varied with the -lactam agent tested. Third-generation cephalosporins were weak inducers of -lactamases, and their use as therapy preceded the appearance of strains that produce chromosomal group I -lactamases constitutively. These strains showed a remarkable reduction in sensitivity to ureidopenicillins, carboxipenicillins, third-generation cephalosporins, and monobactams, but not to carbapenems.     

Changes in the susceptibility ofBacteroides fragilis group organisms to various antimicrobial agents 1979–1989

The in vitro activity of metronidazole, chloramphenicol, clindamycin and 11 -lactam antibiotics against 135 clinical isolates of theBacteroides fragilis group was compared. In addition, changes in the resistance patterns of members of theBacteroides fragilis group isolated at the Hospital Universitario San Carlos in Madrid, Spain, between 1979 and 1989 were documented. The most active -lactam drugs were imipenem and -lactamase inhibitor combinations. In 1989, however, two strains were found to be resistant to imipenem and to all other -lactam agents tested. There was no emergence of resistance to metronidazole. Chloramphenicol was very effective: only one resistant strain was detected in 1979 and no chloramphenicol-resistant isolates were found during the rest of the study period. An outbreak of clindamycin resistance was noted in 1982, and the first cefoxitin resistant strains were recovered in 1985. The changing patterns of susceptibility of anaerobic bacteria to antimicrobial agents and the emergence ofBacteroides fragilis strains resistant to new -lactam agents suggest that periodic antimicrobial susceptibility tests should be performed in order to guide the selection of antimicrobial agents for therapy.     

Immunohistochemical studies on S-100 cells in the anterior pituitary gland of Sprague Dawley rats and spontaneous dwarf rats

The S-100 cells in the pituitary glands of adult male Sprague Dawley rats (SDs) and spontaneous dwarf rats (SDRs) were immunohistochemically examined using anti-S-100 and anti-S-100 monoclonal antibodies. The immunoreactive cells against S-100 protein were divided into three subtypes on the basis of their immunore-activity against subunits of S-100 protein: S-100 dominant type (the -type cell), S-100 dominant type (the \-type cell) and immunoreactive against both S-100 and S-100 (the -type cell). In the SD, -type cells represented 26% of the total S-100 immunoreactive cells (S-100 cells) and were localized in the peripheral area of the ventral region of the pituitary gland. This type of cell was observed forming clusters, with more abundant cytoplasm than the -type cell. The proportion of -type cells was 53%. They were diffusely distributed throughout the gland, and their processes were thicker than those of the -type cell. In the SDR, the proportion of -type cells was 55%, and they were observed throughout the gland. In contrast, -type cells totalled 12% and were localized in small areas of the central and peripheral region of the gland. The proportion of -type cells was 21% in the SD and 33% in the SDR and they were observed forming small clusters in both animal groups. The proportion of -type cells compared with the total of S-100-immunoreactive cells was significantly higher (P < 0.05) in the SDR than in the SD, while the proportion of -type cells was markedly lower (P < 0.05).     

Susceptibility ofBacteroides non-fragilis and fusobacteria to amoxicillin,amoxicillin/clavulanate,ticarcillin, ticarcillin/clavulanate,cefoxitin, imipenem and metronidazole

The susceptibility of 234Bacteroides non-fragilis strains and 56 fusobacteria from 12 European centers to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole was tested and related to -lactamase production. Beta-lactamase production was detected in 42.3 % of theBacteroides strains and 26.8 % of the fusobacteria. The MIC90 of amoxicillin for -lactamase-negative strains was 0.5 µg/ml and the MIC90 of ticarcillin 2.0 µg/ml. In the case of -lactamase-positive strains the MIC90 of amoxicillin (32 µg/ml) and ticarcillin (16 µg/ml) dropped to 1.0 µg/ml upon addition of clavulanate; 65.8 % of these strains were susceptible to amoxicillin and 98.2 % to ticarcillin, but all were susceptible when clavulanate was added. All strains were susceptible to imipenem and metronidazole, and 99.3 % to cefoxitin.     

Detection of SHV-5 extended-spectrum beta-lactamase inKlebsiella pneumoniae strains isolated in Italy

Thirty-fiveKlebsiella pneumoniae strains isolated during 1993–1994 in intensive care units of a large Italian hospital were examined for the presence of extended-spectrum -lactamases. Five strains showed a high level of simultaneous resistance to -lactam agents, including ceftazidime and aztreonam, conferred by a large (130 kb) self-transferable plasmid (in 4 of 5 strains). Isoelectrofocusing and hybridisation studies suggest that these enzymes can be identified as SHV-5 extended-spectrum -lactamases. Pulsed-field gel electrophoresis analysis showed three different genomic fingerprinting profiles, while plasmid restriction enzyme digestion revealed three different patterns, demonstrating that the diffusion of SHV-5 -lactamase is not the result of a single strain or plasmid dissemination.     

Selection and properties ofPseudomonas aeruginosa variants resistant to beta-lactam antibiotics

The relation between basal and inducible-lactamase production and resistance to-lactam compounds was studied in five clinicalPseudomonas aemginosa isolates and their corresponding resistant variants selected in the presence of either piperacillin, ceftazidime or aztreonam. In all wild-type strains enzyme levels were barely detectable in the uninduced state and most-lactams, including sulbactam and clavulanic acid, exhibited poor induction potency. Imipenem proved to be the most potent inducer in both these strains and their resistant variants. In the variants selected by either piperacillin or ceftazidime enzyme production amounted to 1.28 units/mg protein of the cell-free supernatants following the addition of-lactams as inducers. Additionally, these variants exhibited the phenomenon of non-specific induction, i.e. the increase of enzyme production by either a complex nutrient medium or by addition of vitamins. Enzyme production in the aztreonam-resistant variants was identical to that in the wild-type strains with a single exception, where the entire derepression of-lactamase production in one of the variants took place. Derepression of the chromosomally mediated enzyme affects the susceptibility to ureidopenicillins more than that to carboxy-penicillins and cephalosporins, whereas the-lactamase-independent resistance results in increased resistance to all-lactams with the single exception of imipenem.     

Activity of beta-lactamase inhibitor combinations onEscherichia coli isolates exhibiting various patterns of resistance to beta-lactam agents

The efficacy of the clinically available -lactam/-lactamase inhibitor combinations (amoxicillin/clavulanic acid (CA), ticarcillin/CA, amoxicillin/sulbactam, and piperacillin/ tazobactam) was evaluated on 300 amoxicillin-resistantEscherichia coli isolates having the main patterns of -lactam resistance. The patterns, which reflect the production of various -lactamase enzymes, were analyzed by a principal component analysis of susceptibility to 11 -lactam antibiotics or -lactam/-lactamase inhibitor combinations. Sixty-two percent of strains were not very susceptible to penicillins, cephalothin, or any -lactam/-lactamase inhibitor combinations except for piperacillin/tazobactam; these strains may represent high-level broad-spectrum -lactamase (so-called penicillinase) production phenotype or inhibitor-resistant TEM-like enzyme production phenotype. Of the strains, 14.7 % were resistant to amoxicillin and ticarcillin compatible with low-level broad-spectrum -lactamase production phenotype; 5.7 % were cefoxitin resistant and were postulated to present a high-level cephalosporinase production phenotype; and 2.6 % were resistant to cephalothin only, attributable to a low-level cephalosporinase production phenotype. Three percent of strains were intermediate or resistant to cefotaxime and may produce an extended-spectrum -lactamase, and the remaining strains (12 %), resistant to all tested antibiotics except for cefotaxime and piperacillin/tazobactam, were hypothesized to produce both broad-spectrum -lactamase plus cephalosporinase. The minimal inhibitory concentration (MIC) for these phenotype patterns indicated that combinations of CA plus amoxicillin or ticarcillin, or sulbactam plus amoxicillin, restored the activity of penicillins against phenotype 1 strains, whereas these combinations remained inactive against the other phenotype strains. Piperacillin plus tazobactam showed the best in vitro effect against the strains of all resistance phenotypes.     

Density heterogeneities of hepatitis C virus in human sera due to the binding of β-lipoproteins and immunoglobulins

Heterogeneities in the density of hepatitis C virus RNA-carrying material (HCV-RNA-CM) found in human sera (1.03–1.20 g/cm³) are attributed to the binding of low-density lipoproteins and/or of IgG. In some sera HCV-RNA-CM seems to be nearly totally bound to -lipoproteins and cannot be precipitated by anti-IgG (); in others more than 95% of HCV-RNA-CM is bound to IgG and cannot be precipitated by anti--lipoprotein. Furthermore, there are sera from which HCV-RNA-CM can be completely be precipitated by either anti--lipoprotein or anti-IgG (), pointing to a binding of the two serum proteins to the same HCV-RNA-CM. There are other sera from which HCV-RNA-CM can be partially precipitated by the one or the other antiserum, leaving behind fractions, which are bound to -lipoprotein or to IgG. HCV-RNA-CM cannot be precipitated from some sera either by anti--lipoprotein or by anti-IgG ().     

Beta-lactamase types and beta-lactam resistance ofEscherichia coli strains with chromosomally mediated ampicillin resistance

On the basis of isoelectric focusing six -lactamase types could be distinguished in ampicillin-resistant and ampicillin-sensitive strains ofEscherichia coli. More than 90% of the ampicillin-resistant strains produced the same -lactamase type. The serotypes found in a group of ampicillin-resistant urinary tract infection strains did not represent the distribution usually found in urinary tract isolates. Chromosomal ampicillin resistance was always associated with high cephalothin MIC values and increased resistance to other -lactam antibiotics of the cephalosporin group.     

Distribution of skeletofusimotor axons in lumbrical muscles of the monkey

Summary The nerve supply to 25 poles of muscle spindles in the monkey was reconstructed by light microscopy of serial 1-m thick transverse sections of lumbrical muscles. Twenty of 60 motor axons that supplied the spindle poles were identified as skeletofusimotor (). Twenty-eight percent of the spindle poles were innervated by axons, in addition to axons. Every -innervated spindle pole transected an endplate zone of extrafusal muscle. Most axons coinnervated extrafusal fibers rich in mitochondria and the nuclear bag₁ or nuclear chain intrafusal fibers. All but two axons innervated one type of intrafusal fiber only. The intramuscular organization of motor system in lumbrical muscles of the monkey was similar to that of the cat tenuissimus muscle. The function of -innervated spindles may be preferentially to monitor mechanical disturbances arising from the activity of extrafusal muscle units with which they share motor innervation.     

Phenotypic characteristics of lewis lung carcinoma cells

We studied adhesive properties and physiological activity in vivo of cells from Lewis lung carcinoma and its metastases. These cells differed in tumorogenic activity and metastatic potential in the syngeneic system. In vivo non-metastasizing cells are characterized by a lower content of surface lectins to tetrasaccharides SiaLe^x [Neu5Ac2-3Gal1-4(Fuc1-3) GlcNAc] and SiaLe^a [Neu5Ac2-3Gal1-3(Fuc1-4)GlcNAc] and trisaccharide HSO₃Le^x [HSO₃2-3Gal1-4(Fuc1-3)GlcNAc] compared to cells forming metastases in the syngeneic system. Metastatic cells with low tumorogenic activity weakly expressed lectins to disaccharide ligands 6-SiaLac [Neu5Ac2-6Gal1-4Glc], 6-HSO₃LacNAc, and A-di [GalNAc 1-3Gal] and trisaccharides H-type 1 [Fuc1-2Gal1-3GlcNAc and Le^x [Fuc1-3(Gal 1-4)GlcNAc] compared to cells that initiated tumor formation in the syngeneic system (similarly to transplanted tumors). We hypothesized that cell receptors to these carbohydrate determinates are involved in the development and growth of primary tumors, while lectins to SiaLe^x, SiaLe^a, and HSO₃Le^x play a role in the progress of tumor process and metastasizing.     

Oxidant-scavenging activities of beta-lactam agents

The relative antioxidant effect of ampicillin, ceftazidime, ceftriaxone, and cefuroxime on oxygenreactive species was examined in vitro using stimulated human polymorphonuclear neutrophils. There was no evidence that any of the -lactam agents tested had an effect on superoxide or H₂O₂ generation. In contrast, all of the -lactam agents prevented hypochlorous acid (HOCl) chlorination of 1,1-dimethyl-4-chloro-3,5-cyclo-hexanedione in a cell-free system at concentrations of <10 g/ml. Furthermore, all antibiotics provided dose-dependent protection against HOCl cytotoxicity to 16HBE140 bronchial epithelial cells. Taken together, these data indicate a possible therapeutic role for -lactam agents in protecting host tissues from HOCl-induced oxidative damage.     

α and β glucocorticoid receptor mRNA expressionin skeletal muscle

The aim of the present study was to investigate the occurrence and autoregulation of both glucocorticoid receptor mRNAs in rat gastrocnemius muscle. The expression of both receptor forms was studied 1, 4 or 12hours after intra-tracheal instillation of a high dose (100g) of budesonide; muscular expression was compared with glucocorticoid receptor expression in lung tissue. After Northern blot analysis, hybridization was performed with glucocorticoid receptor, glyceraldehyde-3-phosphate dehydrogenase and glutamine synthetase probes. In the gastrocnemius muscle, both the and glucocorticoid receptor mRNA forms were detected and found to be downregulated four hours after the budesonide instillation. / glucocorticoid receptor ratios were lower in the gastrocnemius (1.1±0.2) than in the lungs (2.6±0.6). In the lungs, at all time points, the average glucocorticoid receptor mRNA levels did not differ from controls, although glutamine synthetase mRNA levels were upregulated. The glucocorticoid receptor mRNA was slightly reduced at 1 and 4hours. In conclusion, after intra-tracheal instillation of budesonide, both and glucocorticoid receptor forms were downregulated in muscle tissue. The difference in / glucocorticoid receptor mRNA ratios and concentrations between lung and gastrocnemius muscle supports the hypothesis of differential gene regulation by glucocorticoids in different cell types. © Kluwer Academic Publishers.     

Unterschiedlich hoher Ureterdruck in Abhängigkeit von der Diureseform beim Hund

Zusammenfassung Bei Vorliegen einer normalen Diurese wird nach Ureterabklemmung der sog. hohe Ureterdruck, unter osmotischer Diurese der maximale erreicht. Die Differenz von Blutdruck und maximalem Ureterdruck war im Mittel der Versuche um 20 mm Hg kleiner als diejenige des hohen. Die Ursache dafür wird kurz diskutiert.Herrn Prof. Dr.S. Janssen zum 70. Geburtstag gewidmet.     

Clinical significance of beta-lactamase induction and stable derepression in gram-negative rods

Most strains of enterobacteria andPseudomonas aeruginosa produce chromosomally-determined Class I-lactamases. When synthesized copiously these enzymes cause resistance to almost all-lactams, except imipenem and, sometimes, carbenicillin and tenocillin. Elevated-lactamase production arises transiently, via induction, inPseudomonas aeruginosa andEnterobacter, Citrobacter, Morganella, indole-positiveProteus andSerratia spp. when these organisms are exposed to-lactams. Permanent high-level enzyme production arises via mutation, in the stably-derepressed mutants of these species. These mutants arise spontaneously at high frequency (10^–5–10^–8). Most early penicillins and first-generation cephalosporins are strong inducers of Class I enzymes at sub-inhibitory concentrations, as are cefoxitin and imipenem. Consequently their MICs reflect what lability these antibiotics have to inducibly-expressed-lactamase. Except with imipenem this lability usually is so great that the inducible enzyme causes clinical resistance. Although most other newer cephalosporins and ureidopenicillins are labile to the Class I enzymes they induce poorly below the MIC, and their lability is not reflected in resistance unless secondary inducers (e.g. cefoxitin or imipenem) are present. Although the weak inducer activity of these agents helps to maintain their activity against the inducible cells it renders the drugs highly selective for the pre-existing stably-derepressed mutants. Many cases have been reported where stably-derepressed mutants have overrun inducible populations of bacteria in patients undergoing therapy with-lactamase-labile weak inducers such as ureidopenicillin and third-generation cephalosporins.     

Decreased serum levels of TGF-β in patients with acutePlasmodium falciparum malaria

Apart from cellular immunity and immunopathology, various cytokines have been implicated in malaria-associated immunosuppression. In this study, serum levels of transforming growth factor- (TGF-) were determined with an enzyme-linked immunosorbent assay in 37 patients with acutePlasmodium falciparum malaria prior to, during, and after therapy and in 17 healthy controls in Bangkok, Thailand. Patients were treated with artesunate and mefloquine. TGF- serum levels were found decreased prior to treatment (14±11 pg/ml versus 63±15 pg/ml in healthy controls;P<0.05). The serum concentrations of TGF- increased after initiation of treatment and were within normal range on day 21. Serum levels of both tumor necrosis factor-ga (TNF-) and soluble TNF-receptor 55 kDa were inversely correlated to serum levels of TGF- (r= –0.667 andr=}-0.592, n=37; respectively,P < 0.05 for both). No correlation between parasitemia and serum levels of TGF- could be found. The results are compatible with a decreased production and release, an enhanced clearance or utilization, or tissue accumulation of TGF- in acuteP. falciparum malaria.     

Altered expression of the steroid bioconverting pathway in pAN 7-1 transformants of Cochliobolus lunatus

Summary The filamentous fungus C. lunatus converts progesterone mainly to its 11-hydroxy derivative. C. lunatus transformed with the plasmid pAN 7-1, which contains the E. coli hph gene expressed under the control of the A. nidulans gpd and trpC expression signals, lacks this activity, but exhibits acetyl side chain degradation of progesterone through the reaction scheme progesterone20-hydroxy-progesterone ⁴-androstene-3,17-dione testolactone+testosterone. The main partof this metabolic pathway is not expressed in the non-transformed strain. It was determined that the site-specific integration of the plasmid into the genome directly influences the expression of genes involved in the bioconversion of steroids.     

Interferon β1a Treatment Modulates TH1 Expression in γδ + T Cells from Relapsing-Remitting Multiple Sclerosis Patients

A paradigm exists that multiple sclerosis is causally related to dysregulation of T_H1 inflammatory cytokines and T_H2 antiinflammatory cytokines. The cytokine source(s) that initiate the imbalances are unknown. In this study, , CD4, and CD8 T cell receptor-positive (TCR+) cells were isolated from the blood of 26 definitive relapsing-remitting multiple sclerosis patients prior to interferon -1a (IFN1a) therapy and following 8–10 weeks of this therapy. The bioactivities of interferon (IFN), interleukin 10 (IL10), and interleukin 12 (IL12) were determined. The concentrations of IFN, IL10, and IL12 from each cell type did not change significantly with IFN1a treatment. The IL10 secreted by TCR+ cells strongly correlated with the IL12 secreted by the same TCR+ cells, supporting the paradigm. Furthermore, IFN1a therapy decreased the TCR+ cell secretion of T_H1 cytokines after 8–10 weeks of therapy.