Evidence for the location of OprM in the Pseudomonas aeruginosa outer membrane

OprM with a M(r) of 49 K is associated with the multidrug resistance of Pseudomonas aeruginosa. Detergent fractionation of bacterial cells has demonstrated that OprM is located in the outer membrane from which it sediments with the other major outer membrane proteins. In this study we have determined the location of OprM as the P. aeruginosa outer membrane. Western immunoblots of cell fractions, obtained by sucrose density gradient centrifugation of whole cell lysates, were probed with an OprM-specific murine polyclonal antiserum.

[In vitro synergistic effects of tazobactam/piperacillin with various antibiotics]

We investigated in vitro synergistic effects of tazobactam/piperacillin (TAZ/PIPC), a combination drug of tazobactam (TAZ) and piperacillin (PIPC) in the ratio of 1:4, with several other antibiotics against Pseudomonas aeruginosa, Serratia marcescens and methicillin-resistant Staphylococcus aureus (MRSA). Synergistic effects of TAZ/PIPC with each of tobramycin (TOB), netilmicin (NTL), fosfomycin (FOM), ciprofloxacin, minocycline or cefoperazone were observed against all bacteria tested in the checkerboard dilution method. No antagonistic effect was observed in combination of TAZ/PIPC with other antibiotics. Against P. aeruginosa, a combination of TAZ/PIPC with NTL was the most effective, with an average fractional inhibitory concentration (FIC) index of 0.459. And a combination of TAZ/PIPC with FOM was the most the effective against S. marcescens and MRSA. TAZ/PIPC combined with TOB or FOM showed bactericidal effect against P. aeruginosa No. 11, S. marcescens No. 39 and S. aureus O-62 at concentrations of the drugs that showed only bacteriostatic activity individually. Phase-contrast micrographic observations of P. aeruginosa No. 11 and S. marcescens No. 39 demonstrated that the bacterial cells treated with TAZ/PIPC were in filamentous forms and those treated with TOB or FOM were nearly normal. The combination of TAZ/PIPC with TOB or FOM induced filamentous cells with spheroplast-like structures and lysis. Those results suggest that the combination of TAZ/PIPC with aminoglycosides or FOM were useful in the treatment of infections by P. aeruginosa, S. marcescens and MRSA, especially those caused by beta-lactamase-producing strains.

Effects of aliphatic alcohols and food additives on nicotinic acetylcholine receptors in Xenopus oocytes

To study the effects of food additives on nicotinic acetylcholine receptors (nAChR), they were expressed in Xenopus oocytes that received an injection of mRNA prepared from electroplax of Electrophorus electricus. The response of nAChR elicited by acetylcholine (ACh) was measured electrophysiologically in the presence and absence of aliphatic alcohols and food additives. All compounds examined inhibited nAChR non-competitively in a concentration-dependent way. The inhibition was stronger when the inhibitors were perfused 1 min before ACh, than when they were perfused simultaneously with ACh. The inhibition of nAChR by aliphatic alcohols (propanol to hexanol) increased as the number of carbon chains increased. The addition of alcohols and food additives did not affect the desensitization of nAChR caused by 2 microM ACh. These results suggest that alcohols and food additives bind to the anesthetic binding site in nAChR and inhibit it noncompetitively. However, these compounds will not hinder signal transmission in neuromuscular junctions under physiological conditions, because their inhibition constants are more than 1 mM and muscles usually have more receptors than the number necessary for signal transmission.

Hormone-dependent human tumors express the fms gene-product

Human mammary and thyroid tumors as well as peripheral blood cells of the same patients were examined for the amplification of oncogene fins and the expression of its product. Of the 7 mammary tumors analyzed, amplification of fms was observed in 6 (86%) mammary tumor DNAs, while no amplification was seen in 5 thyroid tumors and 7 peripheral blood cell DNAs tested. None of the mammary and thyroid tumors showed any rearrangement of the fms gene. Investigations of the expression of the product of fms in various human tumors were carried out following the method of immunohistochemical staining in which polyclonal antibody to the fms gene product was used. The incidence of the expression of fms gene product in the tumors of mammary and thyroid glands, prostate and ovary, the hormone-dependent organs, was 38-97%, whereas fms protein was found to be present only in 20 and 42% of the tumors from hormone-independent organs, the brain and the bladder. Expression of the fms gene product was not detectable in normal tissue surrounding the tumor tissue in any of the cases examined. These results suggest that the expression of the product of fms may be associated with the development of some tumors of hormone responsive organs, especially the breast and thus the fms gene product may be a valuable marker for human mammary tumors.

Thermostable farnesyl diphosphate synthase of Bacillus stearothermophilus: crystallization and site-directed mutagenesis

The gene for thermostable farnesyl diphosphate synthase from Bacillus stearothermophilus was cloned, sequenced, and overexpressed in Escherichia coli. The synthase was purified to homogeneity and crystallized. The enzyme carried only two cysteine residues in contrast to its counterparts from other sources, which have four to six cysteine residues. Either or both of the cysteine residues can be replaced with serine without causing a loss of the catalytic activity. The conserved arginine residue that occupies the third position from the C-terminus was also replaced with valine without significant loss of activity, but the valine mutant showed a weakened affinity for isopentenyl diphosphate.

Novel isoprenoid modified proteins in Halobacteria

Incorporation of [3H]mevalonic acid-derived materials into proteins was studied with extremely halophilic archaebacteria, Halobacterium halobium and Halobacterium cutirubrum. Several labeled proteins were detected on SDS-polyacrylamide gel electrophoresis followed by fluorography. The majority of the radioactive materials released from the labeled proteins by sulfonium salt cleavage moved with a mobility similar to that of a C85 polyprenol on reverse-phase thin-layer chromatography, and no radioactive farnesol was found on the chromatography. However, a weak but significant protein farnesyltransferase activity was detected in in vitro experiments with a combination of [3H]farnesyl diphosphate and Ras precursor protein.

[Intraglomerular distribution of thrombomodulin in patients with various renal diseases]

We investigated the intraglomerular distribution of thrombomodulin (TM) antigen in patients with various renal diseases. The subjects enrolled in this study were 28 patients with IgA nephropathy, 26 with collagen diseases, 10 with toxemia and 4 with DIC. Normal renal cortex used as a control was obtained from the normal pole of kidneys with a tumor of the opposite pole. Intraglomerular distribution of TM antigen was detected by an immunohistochemical method using a polyclonal antibody against human TM. The following results were obtained: 1) The staining intensity of TM on endothelial cells of glomerular tufts was higher in IgA nephropathy and collagen diseases than in the controls, but was the same in toxemia and DIC as in the controls. 2) The staining intensity of TM decreased with the progression of the glomerular lesion in IgA nephropathy and lupus nephritis. These findings suggest that the intraglomerular distribution of TM may be involved in the progression of glomerular lesions and in the acceleration of intraglomerular blood coagulation in various renal diseases.

Breathing route and ventilatory responses to inspiratory resistive loading in humans

In response to ventilatory loading, a number of compensatory mechanisms can serve to maintain ventilation at or near control levels. To test the hypothesis that respiratory compensation for inspiratory flow-resistive load during nasal breathing may be different from that during oral breathing, we investigated the ventilatory responses to four different magnitudes of inspiratory flow-resistive loads ("control," "light," "moderate," and "severe" loads: 3.5, 15.0, 51.8, 83.3 cm H2O/L/s at a flow rate of 30 L/min, respectively) during nasal breathing and during oral breathing in 11 conscious subjects. With the control, light, and moderate loads, there were no significant differences in tidal volume (VT), respiratory frequency (f), minute ventilation (VI), and end-tidal (partial) carbon dioxide pressure (PETCO2) between nasal and oral breathing. With the severe load, however, VI and f were significantly lower and PETCO2 was significantly higher during nasal breathing than during oral breathing. Occlusion pressure (P0.1) progressively increased during both nasal and oral breathing with increasing magnitudes of loading. However, the value of P0.1 during oral breathing at the severe loading was significantly higher than that during nasal breathing. Our results indicate that ventilatory compensation for the inspiratory flow-resistive load is better during oral breathing than during nasal breathing.

[The clinico-pathological significance of hematuria in diabetics]

A clinico-pathological study was performed on 154 patients with diabetes mellitus to clarify the significance of glomerular hematuria. Glomerular hematuria was observed in 26 patients (16.9%), of whom 10 had complications of IgA glomerulonephritis and one had membranous nephropathy. The remaining patients (143 cases) were divided into two groups; a hematuria group (15 cases) and a non-hematuria group (128 cases). Patients in the hematuria group showed diabetic retinopathy, hypertension, massive proteinuria and the requirement for insulin therapy more often than those in the non-hematuria group (p < 0.01, p < 0.001, p < 0.001 and p < 0.01, respectively). In addition, the serum creatinine level in the hematuria group was significantly elevated compared to that in the non-hematuria group (p < 0.01). Histologically, patients in the hematuria group exhibited advanced diffuse lesions, nodular lesions, exudative lesions, microaneurysms, crescent formation, capsular adhesion and interstitial lesions more often than those in the non-hematuria group (all, p < 0.001). Furthermore, the vascular index in the hematuria group was significantly higher than that in the non-hematuria group (p < 0.001). It is suggested that glomerular hematuria in diabetic patients indicates the presence of diabetic nephropathy at an advanced stage or coexistence of primary glomerulonephritis.

Structures of heat-stable and unstable homologues of the sweet protein mabinlin. The difference in the heat stability is due to replacement of a single amino acid residue

There are several analogues of the sweet protein mabinlin. In previous studies, we purified the heat-stable analogue, mabinlin II, from the seeds of Capparis masaikai Lévl. and determined its amino acid sequence [Liu, X., Maeda, S., Hu, Z., Aiuchi, T., Nakaya, K. & Kurihara, Y. (1993) Eur. J. Biochem. 211, 281-287] and the disulfide structure [Nirasawa, S., Liu, X., Nishino, T. & Kurihara, Y. (1993) Biochim. Biophys. Acta 1202, 277-280]. We have now purified four additional homologues of mabinlin. The sweet activities of mabinlin III and mabinlin IV were unchanged by incubation for 1 h at 80 degrees C, as was found previously for mabinlin II, while the sweet activity of mabinlin I-1 was completely abolished by a 1-h incubation at 80 degrees C. The circular dichroic spectrum showed that alpha-helical structures of mabinlins II-IV were unchanged by the 1-h incubation at 80 degrees C, while the alpha-helical structures of mabinlin I-1 were completely destroyed by the 1-h incubation in parallel with the decrease of the sweet activity. To compare the structures of the heat-stable and unstable homologues, we determined their amino acid sequences and the disulfide array. The positions of four disulfide bridges of mabinlin I-1 were the same as those of mabinlin II, suggesting that the disulfide bridges do not contribute to the difference in the heat stability among the homologues. There was a high similarity among amino acid sequences of the homologoues. Only three amino acid residues (A-chain residues at positions 22 and 32 and B-chain residue at position 47) were different between mabinlin I-1 and mabinlin III. A-chain residue at position 32 was lacking in mabinlin IV and the A-chain residue at position 22 was identical in both mabinlin I-1 and mabinlin II. The B-chain residue at position 47 was the only residue present in all three heat-stable homologues (mabinlins II-IV) and is not present in the unstable homologue (mabinlin I-1). This suggests that the difference in the heat stability of mabinlin is due to the difference in a B-chain residue at position 47; the difference in the heat-stable homologues is due to the presence of an arginine residue and the difference of the unstable homologue is due to the presence of glutamine.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of thrombomodulin in patients with focal and segmental glomerulosclerosis (FSGS)

Thrombomodulin (TM), an endothelial cell surface glycoprotein, is a regulatory factor in the intravascular anticoagulant system. Furthermore, its plasma level is believed to reflect injury to the endothelial cell. In searching for changes in intraglomerular coagulation and endothelial cell injury during the clinical course of 14 patients with focal and segmental glomerulosclerosis (FSGS), we evaluated the distribution of thrombomodulin (TM) in the kidney by immunohistochemical methods. In the nephrotic stage, intraglomerular staining for TM was weak and segmental and occurred in 6 out of 9 patients (67%), but the incidence of TM expression was not different significantly from that in the normal kidney. Sclerotic lesion was negative for TM. In all patients with incomplete remission and with complete remission, strong and diffuse staining was seen in intra- and extraglomerular endothelial cells. Moreover, TM was scattered in sclerotic lesions. The present study suggest that the over-expression of TM in remission may be linked to recovery from endothelial cell damage and that TM may be closely involved in the repair of FSGS.

Mouse Mammary Tumor Virus Proviral Integration in the DD/Tbr Mice

The patterns of mouse mammary tumor virus (MMTV) integration in the DNA of spontaneous-mammary tumors, salivary glands and livers of DD/Tbr mice were examined using MMTV env, int -1c and int-2c probes. The MMTV env probe revealed 1 to 7 new proviral insertions in all mammary tumors. MMTV integration into int-1 was observed in 10 of 18 mammary tumors, whereas that into int-2 was seen in only 2 of 18 tumors. Of the 13 salivary glands examined, only 3 showed new MMTV proviral integrations, but rearrangement in int-1 or int-2 loci by MMTV was not observed. Immuno-collidal gold electron microscopy revealed the presence of MMTV particles both in mammary tumors and in salivary glands, but no tumors were found to be developed in salivary glands. Taken together these results suggest that salivary glands support MMTV replication, but the virions thus produced may not lead to salivary gland tumorigenesis. It is suggested that the salivary gland is the source of horizontally transmitted MMTV in DD/Tbr mice.

The identification of Escherichia coli ispB (cel) gene encoding the octaprenyl diphosphate synthase

The gene located upstream of the nlp gene at min 69 on the chromosome of Escherichia coli was cloned from the plasmid pLC7-42 constructed by Clarke and Carbon. The extract of the strain harboring the plasmid containing this gene showed increased activity of the prenyltransferase. The product of the enzyme reaction was analyzed by two systems of the thin-layer chromatography and shown to be the phosphate ester of all-E-octaprenol. These results suggested that the gene was the structural gene for the octaprenyl diphosphate synthase which supplied the precursor of the side chain of the isoprenoid quinones.

The conversion of xanthine dehydrogenase to xanthine oxidase and the role of the enzyme in reperfusion injury

Although mammalian xanthine oxidase exists originally as a dehydrogenase form in freshly prepared samples, it is converted to an oxidase form during purification, either irreversibly by proteolysis or reversibly by sulfhydryl oxidation of the protein molecule. However, avoiding proteolysis the mammalian enzyme can be purified as an interconvertible form and thus can be used to compare directly the properties of xanthine dehydrogenase and the oxidase derived from the same enzyme molecule. The cDNAs encoding the enzyme have been cloned from several sources, and structural information is becoming available. The most significant difference between the two forms is the protein conformation around FAD, which changes the redox potential of the flavin and the reactivity of FAD with the electron acceptors, NAD and molecular oxygen. The flavin semiquinone is thermodynamically stable in xanthine dehydrogenase, but is unstable in xanthine oxidase. Detailed analyses by stopped-flow techniques suggest that the flavin semiquinone reacts with oxygen to form superoxide anion while the fully reduced flavin reacts to form hydrogen peroxide. Although xanthine dehydrogenase can produce greater amounts of superoxide anion than xanthine oxidase during xanthine-oxygen turnover, it seems to be physiologically insignificant because NAD inhibits almost completely the formation of superoxide anion. Although the involvement of this enzyme in reperfusion injury has been proposed, this seems to be more complex than originally envisaged and still remains to be established.

Inhibitory activity on DNA gyrase and intracellular accumulation of quinolones: structure-activity relationship of Q-35 analogs

Q-35, 1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-(3- methylaminopiperidine-1-yl)-4-oxyquinoline-3-carboxylic acid, has excellent activity against gram-positive bacteria and inhibits S. aureus gyrase at concentrations more than 10-fold lower than those of other quinolones. In this paper, the effect of the C-7 and C-8 substituents of Q-35 on the inhibitory activity of gyrase purified from S. aureus, M. luteus, E. coli, and P. aeruginosa are described. In addition, intracellular accumulation of Q-35 was examined. The 50% inhibitory concentrations (IC50) of Q-35, 8-fluoro- Q-35, and 8-hydro-Q-35 on DNA gyrase purified from S. aureus were 2.5, 7.8, and 68 micrograms/ml, respectively. The IC50 on gyrase from P. aeruginosa were 11, 5.2, and 17 micrograms/ml, respectively. It is concluded that the introduction of a methoxy group into the 8 position of the quinolone leads to greater antibacterial activity against gram-positive bacteria. The concentrations of Q-35 which accumulated in S. aureus and E. coli were almost equal to ciprofloxacin, but in P. aeruginosa, Q-35 was lower than ciprofloxacin.

Archaebacterial ether-linked lipid biosynthetic gene. Expression cloning, sequencing, and characterization of geranylgeranyl-diphosphate synthase

Archaebacterial Sulfolobus acidocaldarius geranylgeranyl-diphosphate (GGPP) synthase (EC 2.5.1.29) catalyzes consecutive condensations of isopentenyl diphosphate with allylic diphosphates to produce GGPP which is the important precursor of archaebacterial ether-linked lipids. We developed an expression screening method for cloning the GGPP synthase gene, which utilizes the carotenoid biosynthesis genes of Erwinia uredovora to visualize a clone expressing GGPP synthase, and then screened a genomic DNA library from S. acidocaldarius for the GGPP synthase gene by using this method. Positive clones were shown to contain GGPP synthase gene by the use of an in vitro assay. Extracts from Escherichia coli transformants catalyzed the condensation of isopentenyl diphosphate with farnesyl diphosphate (FPP) to produce (all-E)-GGPP. The nucleotide sequence of the 2.3-kilobase HindIII fragment of the cloned fragment was determined. This sequence specifies two open reading frames, ORF-1 and ORF-2. ORF-1 encodes GGPP synthase with the expected molecular weight of 36,873, and ORF-2 encodes a protein with homology for UDP-N-acetylglucosaminedolichyl phosphate N-acetylglucosaminephosphotransferase. The cloned GGPP synthase was partially purified with several chromatographies after heat treatment of cell free extract. This enzyme is extremely thermostable and has an optimal pH at 5.8. Dimethylallyl diphosphate, geranyl diphosphate, and (all-E)-FPP are, in decreasing order of activity, acceptable as allylic substrates to produce (all-E)-GGPP. When dimethylallyl diphosphate or geranyl diphosphate are the allylic substrates, a significant amount of mixture of the products is shorter than GGPP. (2Z,6E)-FPP is not a substrate. This enzyme recognizes the E-configuration of allylic substrate.

Dissecting aneurysm in the proximal region of the posterior inferior cerebellar artery presenting as Wallenberg's syndrome--case report

A 29-year-old female presented with an unusual case of Wallenberg's syndrome due to a dissecting aneurysm of the posterior inferior cerebellar artery (PICA) manifesting as a sensation of heaviness in the occipital region and vertigo. Magnetic resonance imaging revealed infarction of the lateral aspect of the medulla oblongata. Digital subtraction angiography (DSA) revealed a spindle-shaped dilatation of irregular contour in the proximal portion of the left PICA. Pooling of contrast medium was noted in the venous phase but not double lumen sign. A suboccipital craniectomy confirmed these findings macroscopically. Blood flow meter monitoring before and after proximal clipping of the diseased vessel ensured the safety of the procedure. Follow-up DSA 3 years after surgery revealed no evidence of aneurysm recurrence.

In vitro and in vivo antibacterial activities of FK037, a new parenteral cephalosporin

In vitro and in vivo antibacterial activities of FK037, a new parenteral cephalosporin, were compared with those of cefpirome, ceftazidime and flomoxef. The advantages of in vitro activity of FK037 were as follows: (1) a broad-spectrum antibacterial activity, (2) the most potent activity (MIC90: 25 micrograms/ml) of the cephalosporins tested against highly methicillin-resistant Staphylococcus aureus (H-MRSA), (3) a strong activity against Enterobacter spp. and Citrobacter freundii resistant to the third-generation cephalosporins tested. The MICs of FK037 for 90% of the clinical isolates tested (MIC90s) were 0.012 microgram/ml for Streptococcus pyogenes, 0.05 microgram/ml for Escherichia coli, 0.1 microgram/ml for Streptococcus pneumoniae, 0.2 microgram/ml for Haemophilus influenzae and Proteus mirabilis, 0.39 microgram/ml for Klebsiella pneumoniae, 1.56 micrograms/ml for methicillin-sensitive S. aureus, Proteus vulgaris and Enterobacter aerogenes, 3.13 micrograms/ml for Staphylococcus epidermidis and Moraxella catarrhalis, 6.25 micrograms/ml for C. freundii, 12.5 micrograms/ml for low-level methicillin-resistant S. aureus (L-MRSA), Enterobacter cloacae and Pseudomonas aeruginosa, and 25 micrograms/ml for H-MRSA and Serratia marcescens. FK037 was similar in potency to cefpirome against strains except MRSA, and was superior to ceftazidime and flomoxef against strains except P. vulgaris and/or M. catarrhalis. The increase in MICs of FK037 against 2 L-MRSA strains (2- or 4-fold) was smaller than that of cefpirome and flomoxef (16- to 64-fold) after the third serial culture in the presence of each drug. FK037 was highly bactericidal against S. aureus, E. coli, K. pneumoniae and P. aeruginosa at the MIC or higher. FK037 had a potent protective activity against murine experimental systemic infections due to a wide variety of bacteria. Its protective activity was the strongest among the cephalosporins tested against H-MRSA and Acinetobacter calcoaceticus. Against the other strains, FK037 was as effective as cefpirome and similar or superior to flomoxef and ceftazidime though it was inferior to ceftazidime against P. aeruginosa. Transmission electron microscopic studies revealed that FK037 inhibited septum formation and induced thick cross walls and bacteriolysis at the division sites in MRSA after 4 h incubation.

[Structural analysis of the chromatin loop in human chromosome by immunoelectron microscopy]

Synchronized human lymphocytes were exposed to 5-bromo-2'-deoxyuridine (BrdU) for incorporation in the late S-phase. The substituted chromosome bands were detected immunohistochemically by monoclonal anti-BrdU antibodies with the protein A-gold complex. The bands composed of many chromatin loop clusters were examined by electron microscopy without trypsin treatment. These banding patterns corresponded to the G-band by immunostaining. Chromatin loops were stretched around the chromosome, revealing the structure of coiled chromosome with trypsin treatment. The stretched loops were observed in the whole S-phase without treatment of trypsin but were not seen in the late S-phase. Variations in the degree of stretching were correlated with the duration of the BrdU treatment and the period of trypsin treatment. These results indicate that the trypsin treatment is essential to chromatin loops for their stretching in late S-phase and that the chromosome band is composed of numerous chromatin loops.

Isolation and partial characterization of a novel amino sugar-containing fucan sulfate from commercial Fucus vesiculosus fucoidan

Commercial crude fucoidan (Sigma) from the brown seaweed Fucus vesiculosus was fractionated into its polysaccharide components by gel filtration and anion-exchange chromatography to clarify the structure-anticoagulant activity relationship. The products comprised a wide spectrum of fucans ranging from typical fucoidans (major components) containing mainly fucose, sulfate, and no uronic acid to low sulfate-containing heteropolysaccharide-like fucans (minor components) being composed of neutral sugars other than fucose and a high content of uronic acid(s). The polysaccharide components also had a wide range of molecular weight. The typical fucoidans showed a potent anticoagulant activity, whereas the other fucans had no or only slight activity. One of the fractions found as a minor component, was a novel polysaccharide containing an appreciable amount (11.5%) of glucosamine and a small amount (5.2%) of protein in addition to fucose and sulfate, and having a low apparent molecular weight of 6800. This is the first report that a proteoglycan-like, amino sugar-containing fucan sulfate, composed of fucose, galactose, glucose, mannose, xylose, uronic acid, glucosamine, and sulfate in the molar ratio of 1.00:0.04:0.01:0.48:0.24:0.18:0.56:1.90, could be obtained from brown seaweed. However, this polysaccharide showed no anticoagulant activity.

Responses of tracheobronchial receptors to halothane, enflurane, and isoflurane in anesthetized dogs

We investigated the effects of halothane, enflurane, and isoflurane on the activity of 43 tracheobronchial slowly adapting stretch receptors (SARs) and 16 rapidly adapting irritant receptors (RARs) in 5 anesthetized, vagotomized, paralyzed, and artificially ventilated dogs. The 43 SARs were classified into 2 subtypes: (i) 17 low-threshold SARs with an expiratory discharge at FRC that were active throughout the respiratory cycle and (ii) 26 high-threshold SARs active only in inspiration. Ventilating the lungs with 5% of each anesthetic caused a significant increase in the inspiratory discharge of low-threshold SARs, whereas the expiratory discharge was inhibited or altogether silenced. While the activity of the majority of high-threshold SARs increased during the administration of the three volatile anesthetics, it decreased in those with a particularly high recruitment threshold. There was, however, a consistent increase in the pressure threshold at which all SARs were recruited. Ventilating the lungs with 5% of each anesthetic caused a significant decrease in activity of RARs. Our results indicate that all three halogenated anesthetics inhibit RARs at concentrations ranging from 1% to 5%.

Morphological alterations of Staphylococcus aureus and Streptococcus pyogenes exposed to cefdinir, a new oral broad-spectrum cephalosporin

Affinity for penicillin-binding proteins (PBPs) and the morphological alteration of Staphylococcus aureus 209-P JC and Streptococcus pyogenes C-203 exposed to cefdinir were studied. Although cefdinir was bactericidal against both strains, the extent of the decrease in colony-forming units (CFU) was similar in a fairly wide range of concentrations. Transmission electron microscopy of S. aureus 209-P JC revealed that cefdinir induced thickening of the cross wall and frequent cell lysis at low concentrations. The lytic sites were seen at the site of septum formation. In S. pyogenes C-203, cefdinir induced thickening of the peripheral wall and cross wall, and protoplast-like cells were observed during the incubation period. Cefdinir showed high affinity for all PBPs of S. aureus 209-P JC and S. pyogenes C-203. The drastic changes in the morphology of S. aureus and S. pyogenes were caused by binding of cefdinir to all PBPs.