Biomedical subjects

H Yoneyama

Publications and source records attributed to H Yoneyama.

At least 19 recordsLinked to original sources

PubMed1999

Interplay between the efflux pump and the outer membrane permeability barrier in fluorescent dye accumulation in Pseudomonas aeruginosa.

Pseudomonas aeruginosa encodes three types of xenobiotic efflux pumps, MexAB-OprM, MexCD-OprJ, and MexEF-OprN, which are regulated by the nalB, nfxB, and nfxC genes, respectively, and their high expression renders the cells resistant to multiple species of antibiotics. We evaluated the role of the outer membrane permeability barrier and the efflux pump in lowering the intracellular concentration of fluorescent probes. The wild-type, nalB, nfxB, and nfxC strains with an intact outer membrane showed equally high capability in draining out intracellular fluorescent dye, 2-(4-dimethylaminostyryl)-1-ethylpyridinium and ethidium bromide. When the outer membrane barrier was dismantled by the EDTA treatment, wild-type, nfxC, nfxB, and nalB strains showed significantly different levels of dye accumulation. The polymyxin B-treated cells showed an even more pronounced difference in dye accumulation among the nfxC, nfxB, and nalB mutants. We concluded from these results that the xenobiotic extrusion pumps interplay with the outer membrane permeability barrier in lowering the intracellular substrate concentration. Among three extrusion pumps in P. aeruginosa, MexAB-OprM was the most efficient, followed by MexCD-OprJ and MexEF-OprN pumps for the fluorescent dye extrusion.

Bacterial Outer Membrane Proteins↗

PubMed1999

Uricase-catalyzed oxidation of uric acid using an artificial electron acceptor and fabrication of amperometric uric acid sensors with use of a redox ladder polymer.

Electrochemical oxidation of uric acid catalyzed by uricase (uric acid oxidase, UOx; EC 1.7.3.3) was studied using several redox compounds including 5-methylphenazinium (MP) and 1-methoxy-5-methylphenazinium (MMP) as electron acceptors for UOx, which does not contain any redox cofactor. It was found that MP and MMP were useful to mediate electrons from UOx to an electrode in the enzymatic oxidation of uric acid. A novel redox polymer, poly(N-methyl-o-phenylenediamine)(poly-MPD), containing the MP units was also found to possess the mediation ability for UOx, and poly-MPD was immobilized together with UOx onto an electrode substrate covered with a self-assembled monolayer of 2-aminoethanethiolate with use of glutaraldehyde as a binding agent. The resulting electrode (poly-MPD/UOx/Au) exhibited amperometric responses to uric acid with very fast response of approximately 30 s, allowing reagentless amperometric determination in a concentration range covering that in the blood of a healthy human being. Kinetic parameters of the apparent Michaelis constant and the maximum current response obtained at the poly-MPD/UOx/Au suggested that electrochemical oxidation of uric acid was controlled by diffusion of uric acid into the enzyme film and that the redox polymer worked well in mediating between active sites of UOx molecules and the electrode substrate.

Candida↗

PubMed1999

Membrane topology of the xenobiotic-exporting subunit, MexB, of the MexA,B-OprM extrusion pump in Pseudomonas aeruginosa.

The MexA,B-OprM efflux pump assembly of Pseudomonas aeruginosa consists of two inner membrane proteins and one outer membrane protein. The cytoplasmic membrane protein, MexB, appears to function as the xenobiotic-exporting subunit, whereas the MexA and OprM proteins are supposed to function as the membrane fusion protein and the outer membrane channel protein, respectively. Computer-aided hydropathy analyses of MexB predicted the presence of up to 17 potential transmembrane segments. To verify the prediction, we analyzed the membrane topology of MexB using the alkaline phosphatase gene fusion method. We obtained the following unique characteristics. MexB bears 12 membrane spanning segments leaving both the amino and carboxyl termini in the cytoplasmic side of the inner membrane. Both the first and fourth periplasmic loops had very long hydrophilic domains containing 311 and 314 amino acid residues, respectively. This fact suggests that these loops may interact with other pump subunits, such as the membrane fusion protein MexA and the outer membrane protein OprM. Alignment of the amino- and the carboxyl-terminal halves of MexB showed a 30% homology and transmembrane segments 1, 2, 3, 4, 5, and 6 could be overlaid with the segments 7, 8, 9, 10, 11, and 12, respectively. This result suggested that the MexB has a 2-fold repeat that strengthen the experimentally determined topology model. This paper reports the structure of the pump subunit, MexB, of the MexA,B-OprM efflux pump assembly. This is the first time to verify the topology of the resistant-nodulation-division efflux pump protein.

Amino Acid Sequence↗

PubMed1999

Amperometric determination of total cholesterol at gold electrodes covalently modified with cholesterol oxidase and cholesterol esterase with use of thionin as an electron mediator.

Immobilization of cholesterol oxidase (EC 1.1.3.6) (ChOx) on a gold electrode was attempted by cross-linking using glutaraldehyde between ChOx molecules and a self-assembled monolayer of 2-aminoethanethiolate. The resulting electrode (ChOx/Au) exhibits an amperometric response to free cholesterol in the presence of thionin as an electron mediator, and a steady-state response is obtained approximately 60 s after injection of cholesterol into the electrolyte solution. Coimmobilization of cholesterol esterase (EC 3.1.1.13) (ChE) and ChOx (ChE/ChOx/Au) allows the amperometric determination of both esterified cholesterol and free cholesterol. Cyclic voltammetry of the ChE/ChOx/Au and the dependence of the amperometric response to cholesterol on the concentration of thionin suggest that thionin is encapsulated in the enzyme film on the electrode surface. Apparent Michaelis constants of the ChOx/Au and the ChE/ChOx/Au electrodes suggest that the amperometric response was controlled by penetration of the reaction substrate into the films of the enzyme(s). The concentration of total (free and esterified) cholesterol in human serum samples, determined by using the techniques developed in the present study, is in good agreement with that determined by the well-established technique using colorimetry.

Cholesterol↗

PubMed1999

Effects of 7-nitroindazole on renal sympathetic nerve activity during acute cardiac tamponade in conscious rabbits.

To investigate whether nitric oxide (NO) in the central nervous system is involved in the decrease in renal sympathetic nerve activity (RSNA) during acute cardiac tamponade in conscious rabbits, we examined the effect of 7-nitroindazole (7-NI), a selective inhibitor of neuronal nitric oxide synthase in vivo, on RSNA during acute cardiac tamponade in chronically installed conscious rabbits. Cardiac tamponade was produced by intrapericardial infusion of physiological saline at 2 ml/30 s. Mean arterial pressure (MAP) remained constant initially but RSNA increased to 218+/-24% when we started injection of physiological saline into the pericardial space. Concomitantly after MAP fell to 51+/-1 mm Hg by subsequent injection of the saline into the pericardial space, RSNA decreased to 45+/-6%. If 7-NI (50 mg/kg) was administered intraperitoneally 35 min before the beginning of cardiac tamponade, the decline in RSNA caused by cardiac tamponade was markedly counteracted. Brain nitric oxide synthase (NOS) activity in the cerebral cortex and medulla oblongata, assessed by the conversion of labelled arginine to citrulline, was inhibited by 48% and 44% after the intraperitoneal administration of 7-NI. These results indicate that acute cardiac tamponade elicits a biphasic effect on RSNA, which rises during non-hypotensive period and then falls during hypotension in conscious rabbits. The decrease in RSNA was abolished by treatment with 7-NI, suggesting that the abrupt decrease in RSNA during hypotension induced by acute cardiac tamponade is mediated by NO in the central nervous system.

Acute Disease↗

PubMed1999

Resistance to beta-lactam antibiotics in Pseudomonas aeruginosa due to interplay between the MexAB-OprM efflux pump and beta-lactamase.

We evaluated the roles of the MexAB-OprM efflux pump and beta-lactamase in beta-lactam resistance in Pseudomonas aeruginosa by constructing OprM-deficient, OprM basal level, and OprM fully expressed mutants from beta-lactamase-negative, -inducible, and -overexpressed strains. We conclude that, with the notable exception of imipenem, the MexAB-OprM pump contributes significantly to beta-lactam resistance in both beta-lactamase-negative and beta-lactamase-inducible strains, while the contribution of the MexAB-OprM efflux system is negligible in strains with overexpressed beta-lactamase. Overexpression of the efflux pump alone contributes to the high level of beta-lactam resistance in the absence of beta-lactamase.

Bacterial Outer Membrane Proteins↗

PubMed1999

Active participation of CCR5(+)CD8(+) T lymphocytes in the pathogenesis of liver injury in graft-versus-host disease.

We examined the molecular pathogenesis of graft-versus-host disease-associated (GVHD-associated) liver injury in mice, focusing on the role of chemokines. At the second week after cell transfer in the parent-into-F1 model of GVHD, CD8(+) T cells -- especially donor-derived CD8(+) T cells -- infiltrated the liver, causing both portal hepatitis and nonsuppurative destructive cholangitis (NSDC). These migrating cells expressed CCR5. Moreover, macrophage inflammatory protein-1alpha (MIP-1alpha), one of the ligands for CCR5, was selectively expressed on intralobular bile duct epithelial cells, endothelial cells, and infiltrating macrophages and lymphocytes. Administration of anti-CCR5 antibody dramatically reduced the infiltration of CCR5(+)CD8(+) T lymphocytes into the liver, and consequently protected against liver damage in GVHD. The levels of Fas ligand (FasL) mRNA expression in the liver were also decreased by anti-CCR5 antibody treatment. Anti-MIP-1alpha antibody treatment also reduced liver injury. These results suggest that MIP-1alpha-induced migration of CCR5-expressing CD8(+) T cells into the portal areas of the liver plays a significant role in causing liver injury in GVHD; thus, CCR5 and its ligand may be the novel target molecules of therapeutic intervention of hepatic GVHD.

Acute Disease↗

PubMed1998

Pivotal role of TARC, a CC chemokine, in bacteria-induced fulminant hepatic failure in mice.

Thymus and activation-regulated chemokine (TARC) is a recently identified lymphocyte-directed CC chemokine which specifically chemoattracts T helper type 2 CD4(+) T cells in human. To establish the pathophysiological roles of TARC in vivo, we investigated whether a monoclonal antibody (mAb) against TARC could inhibit the induction of hepatic lesions in murine model using Propionibacterium acnes and lipopolysaccharide (LPS). P. acnes-induced intrahepatic granuloma formation in the priming phase is essential to the subsequent liver injury elicited by a low dose of LPS. The priming phase appears to be dominated by Th1 type immune responses determined by the profile of chemokine and chemokine receptor expression. TARC was selectively produced by granuloma-forming cells, and CC chemokine receptor 4 (CCR4)-expressing CD4(+) T cells migrated into the liver after LPS administration. In vivo injection of anti-TARC mAb just before LPS administration protected the mice from acute lethal liver damage, which was accompanied by a significant reduction of both CCR4 mRNA expression and IL-4 production by liver-infiltrating CD4(+) T cells. Moreover, both TNF-alpha and Fas ligand expressions in the liver were decreased by anti-TARC treatment. These results suggest that recruitment of IL-4-producing CCR4(+) CD4(+) T cells by granuloma-derived TARC into the liver parenchyma may be a key cause of massive liver injury after systemic LPS administration.

Animals↗

PubMed1998

Identification of the catalytic triad of the protein D2 protease in Pseudomonas aeruginosa.

We reported recently that protein D2 (OprD) porin of Pseudomonas aeruginosa bears protease activity (FEBS Letters 394, 179-182, 1996). To identify the catalytic residues of OprD, we introduced the site-directed mutations replacing the putative catalytic triad His156, Asp208, and Ser296 with glutamine, asparagine, and alanine, respectively. The OprD proteins purified from the chromosomal oprD-deficient mutants harboring the plasmids encoding the site-directed mutations showed protease activity less than 0.1% of that of the wild-type OprD. These site-directed mutageneses caused undetectable changes in the pore-forming activity of OprD as measured by single-channel conductance by the planar lipid bilayer. The minimum inhibitory concentration of imipenem in mutants having the replaced catalytic triads was identical with that in the wild-type strain. On the other hand, introduction of the mutation at His367 replacing with glutamine, the site that is supposed to be unrelated to the catalytic sites, showed the unchanged protease activity. These results unequivocally demonstrate that OprD is the protease bearing porin and catalyzes the reaction at His156, Asp208, and Ser296 residues.

Alanine↗

PubMed1998

Subunit swapping in the Mex-extrusion pumps in Pseudomonas aeruginosa.

Pseudomonas aeruginosa encodes three sets of antibiotic extrusion proteins designated as MexA,B.OprM, MexC,D-OprJ and MexE,F-OprN regulated by the nalB, nfxB and nfxC genes, respectively. MexB,D,F, OprM, J,N and MexA,C,E function as the inner membrane pumps, the outer membrane channels and the membrane fusion proteins, respectively. To investigate the possibility of subunit interchangeability, we constructed the following combinations of chimeric pumps: MexA,D-OprM/delta MexB, MexC,B-OprM/delta MexA, and MexA,B-OprJ/delta OprM. The strains producing MexA,D-OprM/delta MexB and MexC,B-OprM/delta MexA failed to restore the antibiotic resistance shown in the strains producing the natural combinations of the subunit proteins. These results suggested that the inner membrane components cannot be interchanged. In contrast, the stains producing MexA,B-OprJ/delta OprM exhibited higher resistance to several antibiotics than the mutant lacking OprM and lower resistance than the strain overexpressing OprM. This result suggests that OprJ may complement the OprM function partially. A spectrum of antibiotics, of which the minimum inhibitory concentrations were restored partially by the complementation, was the same as the spectrum to which the nalB type mutant shows resistance. We surmised from these results that the MexA/MexB unit sustains the substrate specificity of the MexA,B-OprM machinery.

Anti-Bacterial Agents↗

PubMed1998

Do intronic mutations affecting splicing of WT1 exon 9 cause Frasier syndrome?

The WT1 gene, one of the genes responsible for Wilms tumour, is thought to play a crucial role in the development of the kidneys and gonads. This gene encodes four protein isoforms resulting from two alternative splicing sites, one of which involves inclusion or exclusion of lysine, threonine, and serine (KTS) between the third and fourth zinc finger domains. WT1 is virtually always mutationally inactivated in patients with Denys-Drash syndrome. We analysed WT1 in eight patients who had been diagnosed as having this syndrome, and identified five previously unknown mutations affecting splicing donor sites of intron 9. These mutations affect alternative splicing. The isoforms retaining KTS are not produced. The clinical features of the patients with these intronic mutations were consistent with those of Frasier syndrome, characterised by a more slowly progressive nephropathy than Denys-Drash syndrome, associated streak gonads, and no Wilms tumour development. Our results indicate that WT1 isoforms, including/excluding KTS, have different functions in tumorigenesis and organogenesis of the kidneys and gonads.

Adolescent↗

PubMed1998

Symptomatic tonsillar ectopia.

OBJECTIVE: To determine if slight descent of the cerebellar tonsils (< 5 mm below the foramen magnum; tonsillar ectopia) may cause surgically treatable symptomatology. METHODS: A consecutive series of nine symptomatic patients with tonsillar ectopia seen between December 1990 and March 1993 are reported on. The same number of age and sex matched controls were selected at random from outpatients. Twelve asymptomatic subjects with tonsillar ectopia were found among 5000 people between January 1991 and March 1996. Diagnosis of tonsillar ectopia was based on midsagittal MRI. RESULTS: Patients presented mainly with chronic intractable occipital dull pain, vertigo, and dysequilibrium. In all patients MRI showed normal brain structure except for tonsillar ectopia (-2.9 (SD 0.8) mm), which has historically been thought to be of no clinical relevance. In the control group the tonsilar position was +2.1 (SD 2.8) mm (p<0.01). Neurotologically abnormal findings were detected with a monaural speech integration test (100%), eye tracking test (56%), optokinetic nystagmus test (89%), and visual suppression test (67%) which strongly suggested a CNS lesion. In accordance with the results of MRI and precise neurotological examination, posterior fossa decompression surgery was carried out, followed by improvement of preoperative symptoms and less severity of neurotological abnormalities in all patients. CONCLUSION: Tonsillar ectopia could cause neurological symptoms in small populations, which were surgically treatable. Neurotological assessment was necessary to verify the aetiological relation between tonsillar ectopia and various symptoms.

Adult↗

PubMed1998

Blockade of neuronal nitric oxide synthase alters the baroreflex control of heart rate in the rabbit.

In previous studies we used NG-nitro-L-arginine (L-NNA) to investigate the role of nitric oxide (NO) in baroreflex control of heart rate (HR) and renal sympathetic nerve activity (RSNA). L-NNA increased resting mean arterial pressure (MAP), decreased HR, and did not change or slightly decreased RSNA. These changes complicated the assessment of the central effects of NO on the baroreflex control of HR and RSNA. Therefore, in the present study the effects of the relatively selective neuronal NO synthase inhibitor 7-nitroindazole (7-NI) on the baroreflex control of HR and RSNA were investigated in rabbits. Intraperitoneal injection of 7-NI (50 mg/kg) had no effect on resting HR, MAP, or RSNA. 7-NI significantly reduced the lower plateau of the HR-MAP baroreflex curve from 140 +/- 4 to 125 +/- 4 and from 177 +/- 10 to 120 +/- 9 beats/min in conscious and anesthetized preparations, respectively (P < 0.05). In contrast, there was no significant difference in the RSNA-MAP curves before and after 7-NI administration in conscious or anesthetized preparations. These data suggest that blockade of neuronal NO synthase influences baroreflex control of HR but not of RSNA in rabbits.

Animals↗

PubMed1997

Antibiotic diffusion pathways in the outer membrane of Pseudomonas aeruginosa.

We investigated the effect of a temperature shift from 37 degrees C to 17 degrees C on the steady-state diffusion rate of imipenem and cephalothin by evaluating periplasmic drug concentrations in intact cells of Pseudomonas aeruginosa, which overexpresses the extended spectrum beta-lactamase. We found that the ratio of periplasmic imipenem concentration at 17 degrees C relative to that of 37 degrees C was 1.03+/-0.1, whereas that of cephalothin was 0.43+/- 0.09. Accumulation rates of cell-associated tetracycline and fluoroquinolone at 17 degrees C were roughly 1/16 and 1/8, respectively, compared with that at 37 degrees C. We concluded from these data that cephalothin and possibly most other antibiotics excepting carbapenems cross the outer membrane of P. aeruginosa mainly by dissolving in the lipid phase but probably not passing through the porin channel. This may explain why the outer membrane of P. aeruginosa is a tight barrier against the penetration of antibiotics.

Anti-Bacterial Agents↗

PubMed1997

Use of fluorescence probes to monitor function of the subunit proteins of the MexA-MexB-oprM drug extrusion machinery in Pseudomonas aeruginosa.

The MexA-MexB-OprM efflux pump of Pseudomonas aeruginosa consists of two inner membrane proteins, MexA and MexB, and one outer membrane protein, OprM. We investigated the role of the components of this drug extrusion system by evaluating the repercussions of deleting these subunit components on the accumulation of several fluorescent probes. Fluorescence intensities of positively charged 2-(4-dimethylaminostyryl)-1ethylpyridinium and uncharged N-phenyl-1-naphtylamine were 7 and 4 times higher, respectively, in the mutant lacking OprM and 4 and 1.7 times higher, respectively, in the mutants lacking MexA or MexB than in the wild type strain. This order of fluorescence intensity was fully consistent with a previously reported minimum inhibitory concentration of antibiotics such as tetracycline, chloramphenicol, and fluoroquinolones. Ethidium bromide accumulation in all the Mex mutants proceeded at about 5 times faster than the rate in the wild type cells. This result is in accord with the minimum inhibitory concentration of beta-lactam antibiotics. These results suggest that the fluorescence probes could be successfully used in real time monitoring of the function of the drug extrusion machinery in Gram-negative bacteria. The downhill extrusion kinetics of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene, which orients perpendicular to the inner leaflet of the cytoplasmic membrane, from preloaded cells lacking the extrusion pump was preceded by a slow increase in fluorescence intensity, whereas the wild type cell immediately released the dye. This observation was explained by a slow trans-cytoplasmic membrane crossing of intracellular dye in the mutants. These results reflected higher accumulation of the probe in the cytoplasmic membrane in the mutants and strengthened the hypothesis that extrusion of hydrophobic substrate mediated by MexA-MexB-OprM mainly takes place from the interior of the cytoplasmic membrane.

1-Naphthylamine↗

PubMed1997

Optical and electron paramagnetic resonance absorption spectra of complexes of nitric oxide synthase I with isocyanides.

Neuronal nitric oxide synthase (NOS I) was purified from porcine brains, and optical and EPR spectra of the complexes of NOS I with isocyanides were investigated. The complex of oxidized NOS I with tert-butylisocyanide exhibited optical absorption peaks at 437 and 560 nm in the difference spectrum, whereas with tert-butylisocyanide and phenylisocyanide, optically reduced NOS I-isocyanide complexes with absorbance maxima at 433, 451, 541 and 573 nm were produced. The dissociation constants of the NOS I-isocyanide complexes were optically determined, the constants being significantly larger than those of microsomal cytochromes P-450. Phenylisocyanide did not affect the optical spectrum of oxidized NOS I. A high concentration of phenylisocyanide also had no effect on the EPR spectrum of oxidized NOS I. The optical spectra of the reduced NOS I-isocyanide complexes were pH-dependent. With increasing pH, the intensity of the absorbance at 451 nm of the complexes increased and that of the absorbance at 433 nm decreased in parallel. Upon the addition of a saturating concentration of L-arginine, the difference spectra of the reduced NOS I-phenylisocyanides complex showed a drastic change, i.e., an increase in optical intensity at 433 nm and a concomitant decrease in the intensity at 451 nm. In titration experiments with L-arginine, spectral binding, Ks = 2.5 microM, was determined from the absorbance increase at 433 nm. No spectral change was observed on the addition of the same concentration of D-arginine. N(omega)-nitro-L-arginine methyl ester (NAME), a potent inhibitor of NOS I, had a similar effect to L-arginine, but the time course of the spectral change was very slow. These results suggest that: (1) the heme-iron pocket of NOS I will be narrower than those of the microsomal and mitochondrial cytochromes P-450; and (2) the binding of L-arginine and its analogue to their binding sites caused conformational changes around the ferrous heme moiety of NOS I.

Animals↗

PubMed1997

The role of mex-gene products in antibiotic extrusion in Pseudomonas aeruginosa.

The antibiotic extrusion machinery in Pseudomonas aeruginosa is assembled from the mex-operon encoded proteins, OprM and MexA-MexB, connecting the outer and inner membranes. To envisage the role of these proteins in antibiotic extrusion and resistance, we employed the gene replacement technique to construct mutants deficient in mexA, mexB, or oprM, and all possible combinations of these genes. Using the Southern and the Western blotting methods, we confirmed that only the target genes were disrupted. All the mutants deficient in OprM exhibited a 4 to 16 times higher susceptibility against quinolone antibiotics, chloramphenicol, and gentamicin than the parent strain. The mutants deficient in MexA or MexB or both MexA and MexB were only 2 to 4 times more susceptible to these antibiotics than the parent strain. All the mutants lacking MexA, MexB, or OprM showed stereospecific hypersusceptibility to beta-lactam antibiotics than the parent strain. However, the extent of susceptibility to each beta-lactam was comparable among the mutants. Strains lacking OprM accumulated the highest level of ciprofloxacin among all these isogenic strains. The strains lacking either MexA or MexB accumulated lower levels of ciprofloxacin than the mutant lacking OprM, but the levels were still higher than in the parent strain. The results are consistent with the antibiotic susceptibility of these strains. These results suggest that the extrusion of antibiotics occurs most efficiently with a whole assembly of MexA/B-OprM, but it remains a possibility that OprM interacts with a putative inner membrane pump(s).

4-Quinolones↗

PubMed1997

[Clinical and laboratory findings associated with the severity of community-acquired pneumonia].

To clarify the clinical features of severe community-acquired pneumonia, we retrospectively studied 121 patients treated at our hospital. We divided the patients into three groups, based on the severity, of their disease. Patients were put in the "mild" group (n = 56) if they recovered after treatment with antimicrobial agents only, they were put in the "moderate" group (n = 34) if the required oxygen therapy and recovered, and they were put in the "severe" group (n = 31) if they required mechanical ventilation. Age and underlying disease were recorded, as well as signs, symptoms, and laboratory data obtained during the first 24 hours after admission. The data indicated that the following nine findings were associated with the severity of disease: age of at least 65 years, an underlying disease of (31) the respiratory or central nervous system, dyspnea, a pulse rate of at least 90 beats per minute, a respiratory rate of at least 25 breaths per minute, an albumin concentration no greater than 3.5 g/dl, a blood urea nitrogen level of at least 20 mg/dl, a PaO2 no greater than 60 mmHg or an SaO2 no greater than 90%, and a high score on a scale of the extent of roentgenographic evidence of pulmonary infiltrates. Patients in whom these are found be managed carefully.

Adult↗