Biomedical subjects

A Weintraub

Publications and source records attributed to A Weintraub.

At least 91 records · Page 5Linked to original sources

PubMed1994

Vibrio cholerae O139 Bengal possesses a capsular polysaccharide which may confer increased virulence.

A newly described Vibrio cholerae serogroup--O139 Bengal, the causative agent of the recent large epidemics of cholera-like disease in the Indian subcontinent and neighbouring countries--possesses a high molecular weight capsular polysaccharide (CPS) that can be visualized by electron microscopy and in composition differs from the lipopolysaccharide (LPS). The CPS and LPS can be separated from each other by a two-step extraction procedure, a phenol-water extraction in order to extract all polysaccharides from the bacterial suspension followed by a phenol-chloroform-petroleum ether (PCP) extraction. The CPS is mainly composed of 3,6-dideoxyhexose (abequose or colitose), quinovosamine and glucosamine. The LPS of the O139 Bengal strain appears to possess a short polysaccharide which contains glucose, galactose, glucosamine and heptose. Both the LPS and CPS are immunogenic. They react in an enzyme immunoassay with rabbit antibodies generated against whole heat-killed bacteria. By analogy with other capsulated bacteria, the possession of a capsule may confer increased virulence of O139 Bengal.

Bacterial Capsules↗

PubMed1994

Gastroesophageal reflux during gastrostomy feeding.

BACKGROUND/AIMS: Aspiration pneumonia is one of the most serious complications of gastrostomy tube feeding, with a reported incidence of 10%-20% in nursing home patients. The aims of this prospective study were to examine lower esophageal sphincter (LES) pressure before and after placement of gastrostomy tubes and to examine the effects of rapid intragastric bolus and slow, continuous feeding on LES pressure. METHODS: Ten subjects were enrolled in the study. Basal LES pressure was measured before and after placement of gastrostomy tubes. Thereafter, LES pressure was measured for 15 minutes during rapid intragastric infusion of 250 mL of an enteral feeding formula and 100 mL water and continuous infusion of the enteral feeding formula at 80 mL/h. Scintigrams evaluating gastroesophageal reflux were obtained during each method of feeding. RESULTS: Placement of gastrostomy tubes had no effect on basal LES pressure. Rapid intragastric bolus infusion led to a reduction in LES pressure to incompetent levels at 2.1 +/- 2.0 mm Hg (P < 0.001). Free gastroesophageal reflux to the sternal notch was shown by scintigraphy. Slow, continuous gastrostomy feedings did not alter LES pressure (P > 0.05) or show free gastroesophageal reflux by scintigraphy. CONCLUSIONS: Gastroesophageal reflux and aspiration in patients fed via the gastrostomy tube may be caused by LES relaxation secondary to gastric distention caused by distention of the stomach.

Aged↗

PubMed1994

Immunochemical identification of Brucella abortus lipopolysaccharide epitopes.

Sera from Brucella abortus-infected and -vaccinated bovines recognized four lipopolysaccharide (LPS) determinants: two in the O-polysaccharide (A and C), one in the core oligosaccharide from rough Brucella LPS (R), and one in lipid A (LA). From 46 different hybridomas secreting monoclonal antibodies (MAbs) against various LPS moieties, 9 different specificities were identified. Two epitopes, A and C/Y, were present in the O-polysaccharide. Two epitopes were found in the core oligosaccharide (R1 and R2) of rough Brucella LPS. MAbs against R1 and R2 epitopes reacted against LPS from different rough Brucella species; however, MAbs directed to the R2 epitope also reacted against enterobacterial LPS from deep rough mutants. Three epitopes (LA1, LA2, and LA3) were located in the lipid A backbone. Different sets of MAbs recognized two epitopes in the lipid A-associated outer membrane protein (LAOmp3-1 and LAOmp3-2). LPS preparations from smooth brucellae had small amounts of rough-type LPS. Although LPS from rough brucellae did not show smooth-type LPS in western blots (immunoblots), two hybridomas generated from mice immunized with rough B. abortus produced antibodies against smooth B. abortus LPS. Results are discussed in relation to the structure and function of B. abortus LPS and to previous findings on the epitopic density of the molecule.

Animals↗

PubMed1994

New perspectives on neonatal hyperbilirubinemia.

Notwithstanding a number of advances in the understanding of hyperbilirubinemia and its treatment in the newborn, controversy continues. The trend has been to decrease interventions and observe and manage infants with jaundice as outpatients. This trend will probably prove to be both medically and economically sound. In the absence of significant hemolysis or other underlying medical conditions such as infection, many physicians are now comfortable with expectant observation for those healthy full-term infants with serum bilirubin measurements of less than 18 mg/dL. New thinking about this condition and advances in treatment may transform hyperbilirubinemia in neonates into a medical curiosity.

Bilirubin↗

PubMed1993

Structural studies of the O-antigenic polysaccharide of an enteroaggregative Escherichia coli strain.

The polysaccharide part of the lipopolysaccharide obtained from an enteroaggregative Escherichia coli strain isolated from a young child with diarrhoea in Santiago, Chile (strain 73-1) was investigated. Sugar and methylation analyses of native and partially degraded polysaccharide together with 1H-NMR and 13C-NMR spectroscopy revealed that the polysaccharide is built of pentasaccharide repeating units. The structure of the repeating unit of E. coli strain 73-1 O-polysaccharide is (formula: see text)

Carbohydrate Conformation↗

PubMed1993

Expression of the Shigella dysenteriae type-1 lipopolysaccharide repeating unit in Escherichia coli K12/Shigella dysenteriae type-1 hybrids.

The structures of the polysaccharide part of lipopolysaccharides isolated from eight Escherichia coli K12/Shigella dysenteriae type 1 hybrids have been determined using sugar and methylation analysis plus 1H- and 13C-nuclear magnetic resonance spectroscopy. The hybrids express parts of the S. dysenteriae type 1 O-antigen tetrasaccharide repeating unit because of the presence of pSS3, a plasmid expressing an alpha-galactosyl: lipopolysaccharide transferase and pSS9, a pBR322 plasmid expressing S. dysenteriae type 1 rfb genes. The various classes of hybrids are the result of transposon Tn 1000 insertions in pSS9 inactivating different rfb genes. The following structural elements were found. E. coli K12 (pSS3) and E. coli K12 (pSS3, pSS9-6; a class I hybrid); alpha-D-Galp(1-->3)beta-D-GlcpNAc(1-->. Class IV hybrids: E. coli K12 (pSS3, pSS9-36); (pSS3, pSS9-107) and (pSS3, pSS9-114); alpha-L-Rhap(1-->2)alpha-D-Galp(1-->3)beta-D-GlcpNAc(1-->. Class V hybrids: E. coli K12 (pSS3, pSS9-78) and (pSS3, pSS9-111); alpha-L-Rhap(1-->3)alpha-L-Rhap(1-->2)alpha-D-Galp(1-->3)bet a-D-GlcpNAc(1-->. The structural sequences are identical to those found in the lipopolysaccharide from native S. dysenteriae type 1. In the hybrid strains, the terminal non-reducing GlcNAc residue of the E. coli K12 core is fully substituted by S. dysenteriae type 1 repeating units, or parts thereof.

Carbohydrate Sequence↗

PubMed1993

The beta-configuration of the rhamnosidic linkage in Salmonella serogroups C2 and C3 lipopolysaccharide is important for the immunochemistry of the O-antigen 8.

Pairs of synthetic di- and trisaccharide-polyacrylamide (PAA) conjugates, isomers in configuration of the rhamnose residue and related to the sequence abequosyl-(alpha 1-3)-rhamnosyl-(beta 1-2)-mannose (ARM), found in Salmonella serogroup C2 (O-antigens 6,8) and C3 (O-antigens 8,20) lipopolysaccharides, have been used as coating antigens and inhibitors in enzyme immunoassay to evaluate the immunochemical importance of the beta-rhamnosidic linkage in the O-antigen 8. In each pair, the reaction with the factor O:6,8 serum was more pronounced for the synthetic antigen with the beta-rhamnosidic linkage. The ARM-PAA conjugate with the beta-rhamnosidic linkage was found to be 2000 fold more efficient as inhibitor of binding of the factor O:6,8 serum to the AR beta M-PAA conjugate as compared to the alpha-linked analogue. The discrepancy in immunochemical behaviour of the alpha and beta-rhamnose containing ARM oligosaccharides can be explained by conformational differences of the oligosaccharides. A slight cross-reactivity observed in the interaction of antiserum against abequosyl-(alpha 1-3)-mannose, representative of Salmonella O-antigen 4, coupled to BSA, with Salmonella O-factor 8 specific abequosyl-(alpha 1-3)-rhamnose containing conjugates is due to the common terminal immunodominant sugar, abequose.

Antibody Specificity↗

PubMed1993

Antibody response and protection against challenge in mice vaccinated intraperitoneally with a live aroA O4-O9 hybrid Salmonella dublin strain.

An auxotrophic Salmonella dublin (O9,12) strain, SL5631, with a deletion affecting gene aroA, was made into a partial diploid expressing the rfb (O-antigen-repeat-unit-specifying) gene cluster of Salmonella typhimurium (O4,12). By use of O4- and O9-specific antisera in indirect immunofluorescence assays, the resulting hybrid SL7103 was shown to express both the O4- and O9-antigen epitopes in the same bacterium. Qualitative and quantitative sugar analyses by gas-liquid chromatography on peralditol acetates of phenol-water-extracted lipopolysaccharides showed that the S. dublin and S. typhimurium repeating units (estimated on the basis of their tyvelose and abequose contents, respectively) were present in approximately equimolar amounts. The SL7103 hybrid auxotroph was avirulent when given intraperitoneally to NMRI mice in a dose of 10(8) CFU and elicited a protective immunity against intraperitoneal challenge with either virulent S. dublin (50% lethal dose of ca. 1.5 x 10(4) CFU versus < 1 x 10(1) CFU in nonimmunized mice) or virulent S. typhimurium (50% lethal dose of ca. 1 x 10(5) versus < 1 x 10(1) CFU in nonimmunized mice). Compared with the protection elicited in homologous systems (S. dublin SL5631 against S. dublin and S. typhimurium SL1479 against S. typhimurium), the protective efficacy of the hybrid was reduced approximately 70-fold against S. dublin challenge and 100-fold against S. typhimurium challenge. Vaccination with S. typhimurium SL1479 conferred no protection against S. dublin challenge, and vaccination with S. dublin SL5631 conferred no protection against S. typhimurium challenge. The protection elicited by the hybrid strain SL7103 is supposed to be mainly a consequence of serum antibodies directed against the immunodominant O4 and O9 epitopes.

Animals↗

PubMed1992

Enzymatic synthesis and isolation of thymidine diphosphate-6-deoxy-D-xylo-4-hexulose and thymidine diphosphate-L-rhamnose. Production using cloned gene products and separation by HPLC.

A two-step enzymatic synthesis of dTDP-L-rhamnose is developed using enzymes from sonicated extracts of cultures of Escherichia coli K12 strains harboring plasmids containing different parts of the rfb gene cluster of Salmonella enterica LT2. The intermediate dTDP-6-deoxy-D-xylo-4-hexulose was isolated after a 1-h reaction, using only dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase, followed by protein precipitation and desalting by gel chromatography (yield 89%). In a two-step reaction using dTDP-D-glucose and dTDP-D-glucose 4,6-dehydratase in the first step, and with NADPH, dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase in the second hour of incubation, the dTDP-D-glucose was fully converted to dTDP-L-rhamnose. The hexoses of both products were identified by mass spectroscopy. The molar yield of dTDP-L-rhamnose, after protein precipitation, anion-exchange chromatography and desalting by gel chromatography, was 62%, corresponding to more than 150 mg, starting from 250 mg of dTDP-D-glucose. When stored lyophilysed under nitrogen, these products were found to be stable for several months. Both dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose have light absorption maxima at 267 nm, with molar absorption coefficients close to that of dTMP. However, the absorption coefficient of dTDP-6-deoxy-D-xylo-4-hexulose at the absorption maximum of 320 nm (specific for sugars containing keto groups) was found to be approximately 20% higher than values presented earlier. Furthermore, an HPLC technique is presented for determining the net activity of dTDP-6-deoxy-D-xylo-4-hexulose 3,5-epimerase and NADPH:dTDP-6-deoxy-L-lyxo-4-hexulose-4-reductase, based on separation of dTDP-6-deoxy-D-xylo-4-hexulose and dTDP-L-rhamnose. The HPLC technique is also suitable for determination of all the nucleotide components involved in the synthesis.

Bacterial Proteins↗

PubMed1992

Once daily cefixime compared with twice daily trimethoprim/sulfamethoxazole for treatment of urinary tract infection in infants and children.

We conducted a randomized prospective multicenter study to compare the safety and efficacy of once daily oral cefixime (8 mg/kg) to twice daily oral trimethoprim/sulfamethoxazole (TMP/SMX) (8/40 mg/kg/day) for the treatment of acute urinary tract infection in children ages 6 months to 13 years. Seventy-six patients (38 in each group) were studied. Thirty-seven percent were younger than 3 years of age. Escherichia coli was the most common isolate in both groups (85%). Eighty-five percent of all Gram-negative organisms were susceptible to TMP/SMX and all were susceptible to cefixime. Seventy-two percent of all patients were febrile at the time of diagnosis. Both groups were treated for 7 to 10 days. Peripheral white blood cell counts, erythrocyte sedimentation rate, body temperature and urinalysis returned to normal at the same rate in both groups. No failures were observed and relapse occurred in 3 cases within the 4 weeks after treatment (2 in the cefixime group and one in the TMP/SMX group). Side effects were observed in 14% of the cefixime group and 16% of the TMP/SMX group and were all mild enough not to necessitate discontinuation of therapy. We conclude that the efficacy and safety of cefixime administered once daily compared favorably with TMP/SMX administered twice daily for acute uncomplicated urinary tract infection.

Administration, Oral↗

PubMed1992

Multiplane transesophageal echocardiography. Imaging planes, echocardiographic anatomy, and clinical experience with a prototype phased array OmniPlane probe.

Multiplane transesophageal echocardiography is a new exciting development in echocardiography. We examined the methodology and echo-anatomic correlations of multiplane transesophageal echocardiography and its clinical applications in 100 patients. We used a 5-MHz phased array multiplane (OmniPlane) transesophageal probe. In this instrument, the transducer array can be steered through 180 degrees from any transducer location. This provides a vast assembly of imaging planes, allowing for detailed visualization of all dimensions of cardiac anatomy. This report presents our observations on the echocardiographic anatomy seen in various image planes and the unique clinical potential of multiplane transesophageal echocardiography in the diagnostic assessment of cardiovascular disorders. This technique appears to provide incremental diagnostic information that enhances the interpretative ability. Less esophageal probe manipulation is required with consequent decrease in patient discomfort. We conclude that multiplane transesophageal echocardiography enhances the versatility of transesophageal examination and offers many new avenues for developments such as three-dimensional echocardiography.

Echocardiography↗

PubMed1992

Three-dimensional and four-dimensional transesophageal echocardiographic imaging of the heart and aorta in humans using a computed tomographic imaging probe.

We evaluated the clinical applicability of a prototype tomographic transesophageal echocardiographic (TEE) system, which not only provides conventional TEE images but also three-dimensional tissue reconstruction and four-dimensional display capabilities. The probe was used in 16 patients in the echocardiographic laboratory, intensive care unit, and the operating room. The instrument is a 5-MHz, 64-element, phased array unit mounted on a sliding carriage within a casing. After appropriate probe placement within the esophagus, the probe is straightened, a balloon surrounding the probe is inflated, and data acquisition begun with ECG and respiration gating. With computer controlled transducer movement at 1-mm increments, a complete cardiac cycle is recorded at each tomographic level. These are processed using a dedicated four-dimensional software, and displayed as a dynamic three-dimensional tissue image of the heart. We were able to see the dynamic motion of the ventricles and all the valves in the four-dimensional format. In addition to four-dimensional display, we were able to cut and visualize the heart in dynamic mode in any desired plane and also in multiple planes. Patients tolerated the procedure well. We conclude that this tomographic four-dimensional approach, which does not require tedious off-line processing, can easily be performed in patients and has a strong clinical potential.

Aorta↗

PubMed1992

Construction of Salmonella strains with both antigen O4 (of group B) and antigen O9 (of group D).

A Salmonella live vaccine causing both O4- and O9-specific immune responses would be of use, but no reported Salmonella serotype has both of these O antigens. Constructed Salmonella typhimurium strains with an rfb (O-antigen-specifying) gene cluster of type D in the chromosome and one of type B in an F'-rfb+ factor, and those with the reverse combination reacted strongly with both anti-O4 (and anti-O5) and anti-O9 sera and, if they carried recA, could be maintained in this state by growth conditions selective for retention of the F' factor. One of the two B.rfb+ gene clusters of a (P22-lysogenic) S. typhimurium strain with a tandem duplication of a chromosomal segment including hisD and B.rfb+ was replaced (by transduction) by a D.rfb+ gene cluster; the resulting strain was O1+ O4+ O5+ O9+ and stable as such after being made recA. A stable O4+ O9+ derivative of a virulent S. enteritidis (O-group D) strain was made by transducing into it first the join point of an appropriate tandem duplication strain, together with the adjacent B.rfb+ gene cluster, and then srl::Tn10 recA.

Cloning, Molecular↗

PubMed1992

Structural and immunochemical studies of the lipopolysaccharides of Salmonella strains with both antigen O4 and antigen O9.

Two Salmonella hybrid strains, SL5313 (Salmonella typhimurium with a D.rfb+ gene cluster) and SL5396 (S. enteritidis with a B.rfb+ gene cluster), each expressing both O-antigen 4 (of serogroup B) and O-antigen 9 (of serogroup D) were studied by immunofluorescence using a mixture of O4-specific mouse monoclonal and O9-specific rabbit polyclonal antibodies. Bound antibodies, detected by anti-mouse antibody labelled with fluorescein isothiocyanate and anti-rabbit antibody labelled with tetramethylrhodamine isothiocyanate showed that more than 98% of the bacteria expressed both the O4 and O9 epitopes. Phenol-water-extracted lipopolysaccharide from batch-grown cultures subjected to sugar and methylation analyses by gas-liquid chromatography and mass spectrometry were shown to contain abequose (of the O4 epitope) and tyvelose (of the O9 epitope) in ratios of 1:1.5 and 1:2.5 for SL5313 and SL5396, respectively. Isolated polysaccharide chains, obtained by weak-acid hydrolysis of the lipopolysaccharides, were found to contain both O4 and O9 specificities in the same molecule, since polysaccharide bound to O4 antibody attached to a solid-phase-adsorbed O9-specific antibody and vice versa. This demonstrates that in strains SL5313 and SL5396 O chains containing both O4 repeating units (from S. typhimurium) and O9 units (from S. enteritidis) are present.

Antibodies, Bacterial↗

PubMed1991

Properties of a rat monoclonal antibody reactive with both the mannan of Candida species and the O-antigen 6,7 polysaccharide of serogroup C1 salmonellae.

Monoclonal antibody MASC1-MR9 of isotype immunoglobulin M was generated in LOU/C rats by immunization with heat-killed Salmonella thompson (serogroup C1, O-antigen 6,7 lipopolysaccharide) bacteria which had been further enriched for O-antigen by coating with homologous lipopolysaccharide. Eight monoclonal antibodies were selected by screening against the lipopolysaccharide of S. thompson. In a subsequent test against Candida mannan, only one antibody, MASC1-MR9, was reactive. Immunofluorescence microscopy of various yeasts and bacteria with MASC1-MR9 showed that this antibody bound to the surfaces of 142 of 148 Candida strains of 10 different species tested but failed to bind to the surface of Saccharomyces cerevisiae. The Candida strains which failed to bind MASC1-MR9 were all five strains of Candida krusei and the single strain of Candida utilis tested. Several (11 of 33) Salmonella strains belonging to serogroup C1 reacted with this antibody, as expected; however, 1 of 11 strains of Morganella morganii and 4 of 64 strains of Escherichia coli were also reactive. Serum-free supernatants of MASC1-MR9 agglutinated S. thompson, one strain of Salmonella choleraesuis, and 109 of 110 Candida strains tested. The immunochemical properties of MASC1-MR9 as studied by enzyme-linked immunosorbent inhibition assays show that it recognizes an epitope present in the mannan of Candida species as well as in the O-6,7 antigen of Salmonella species.

Agglutination↗

PubMed1991

Intravascular ultrasound assessment of arterial dissection, intimal flaps, and intraarterial thrombi.

Arterial dissection, intimal tears, and intraluminal thrombosis are common sequelae of catheter-based interventional procedures for coronary artery disease. These may not be recognized reliably by contrast angiography. Intravascular ultrasound imaging is an innovative method that allows visualization of the cross-sectional anatomy with high-resolution real-time images. This article presents the recent experience in arterial imaging with this method. Studies documenting the ability of intravascular ultrasound to demonstrate arterial atherosclerosis and to unmask some problems related to atherosclerotic disease and its treatment by catheter-based maneuvers are presented. Problems of arterial dissection, intimal flaps, and intravascular thrombosis are described with in vitro and in vivo documentation of the capability of intravascular ultrasound to visualize these abnormalities. The clinical implications of real-time imaging of intimal flaps and intraluminal clots, and the possible value of this imaging modality in the performance of catheter-based therapeutic procedures for coronary and peripheral arterial disorders are discussed.

Angioplasty↗

PubMed1990

Real-time intravascular ultrasound imaging in humans.

The capability of obtaining cross-sectional, high resolution images of arteries with the use of ultrasound catheters has recently been demonstrated in animal studies. In this study the in vivo feasibility of intravascular ultrasound imaging in humans was evaluated. In 26 patients who had undergone diagnostic cardiac catheterization or iliofemoral arteriography, 1 of 3 different models of 20-MHz ultrasound catheters was advanced retrograde, into the iliac arteries and aorta or anterograde into the femoral arteries and real-time cross-sectional images of the arteries were obtained in all. In 10, the iliac arteries were normal and appeared circular and pulsatile with a 3-layered wall and crisply defined lumens. In 7 patients with nonobstructive plaques, the plaque was easily identified in the ultrasound image as a linear, bright, adynamic echo-dense structure. In 4 with obstructive disease in the iliac artery, the arterial lumen appeared irregular, bordered by a thickened, nonpulsatile wall. Variable grades of atheromatous abnormalities in the wall could be visualized. In all 5 patients with arteriographic evidence of obstructive disease of the femoral artery, intravascular ultrasound displayed reduced lumens and irregular borders with protruding high-intensity echoes in the wall. In all patients, the arterial lumen and the normal or abnormal wall were well visualized in the ultrasound images. There were no complications. This study thus demonstrates the feasibility of intravascular ultrasound imaging of arterial circulation in humans. With further improvements in catheter design and image quality, this imaging approach is likely to have a number of potential applications in the assessment of peripheral and coronary arterial diseases and in guiding interventional therapeutic procedures.

Aorta, Abdominal↗

PubMed1990

Intravascular and intracardiac ultrasound imaging: current research and future directions.

Intravascular and intracardiac ultrasound imaging is a newly emerging catheter-based imaging modality with considerable promise. This review article presents the rationale behind attempts at developing intravascular imaging methods, the design features of intravascular instrumentation, the knowledge obtained with in vitro studies, the in vivo experience in humans, and the potential applications of intravascular imaging in arterial atherosclerosis. The feasibility of pulmonary artery imaging and the potential applications of intracardiac echocardiography are discussed. Finally, future directions in intravascular imaging are outlined.

Blood Vessels↗