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1.  Cloning, sequencing, and expression of the Zymomonas mobilis fructokinase gene and structural comparison of the enzyme with other hexose kinases. 
Journal of Bacteriology  1992;174(11):3455-3460.
The frk gene encoding the enzyme fructokinase (fructose 6-phosphotransferase [EC]) from Zymomonas mobilis has been isolated on a partial TaqI digest fragment of the genome and sequenced. An open reading frame of 906 bp corresponding to 302 amino acids was identified on a 3-kbp TaqI fragment. The deduced amino acid sequence corresponds to the first 20 amino acids (including an N-terminal methionine) determined by amino acid sequencing of the purified protein. The 118 bp preceding the methionine codon on this fragment does not appear to contain a promoter sequence. There was weak expression of the active enzyme in the recombinant Escherichia coli clone under control of the lac promoter on the pUC plasmid. Comparison of the amino acid sequence with that of the glucokinase enzyme (EC from Z. mobilis reveals relatively little homology, despite the fact that fructokinase also binds glucose and has kinetic and structural properties similar to those of glucokinase. Also, there is little homology with hexose kinases that have been sequenced from other organisms. Northern (RNA) blot analysis showed that the frk transcript is 1.2 kb long. Fructokinase activity is elevated up to twofold when Z. mobilis was grown on fructose instead of glucose, and there was a parallel increase in frk mRNA levels. Differential mRNA stability was not a factor, since the half-lives of the frk transcript were 6.2 min for glucose-grown cells and 6.6 min for fructose-grown cells.
PMCID: PMC206027  PMID: 1317376
2.  Sequence and variability of the 5.8S and 26S rRNA genes of Pneumocystis carinii. 
Nucleic Acids Research  1992;20(14):3763-3772.
The sequence of the coding region of the rRNA operon of rat-derived Pneumocystis carinii has been completed, including the genes for 5.8S and 26S rRNA. These genes show homology to the rRNA genes of yeast, and an apparent group I self-splicing intron is present in the 26S rRNA gene. Like a similar intron in the 16S rRNA gene, this intron is in a phylogenetically conserved region. Variation in the 26S rRNA sequence was noted between P. carinii organisms isolated from two different sources.
PMCID: PMC334029  PMID: 1641341
3.  An Improved Technique for Isolated Perfusion of Rat Livers and an Evaluation of Perfusates 
The Journal of surgical research  1992;53(2):158-165.
We have modified the apparatus for isolated rat liver perfusion (IPRL) in order to be able to perform two perfusions simultaneously. In addition, we studied the quality and stability of livers by comparison of five different perfusates: Blood (Group A), Original Krebs Henseleit buffer (Group B), Krebs buffer with glucose (Group C) or bovine serum albumin (BSA) added, (Group D). In a last group (E) albumin, glucose, and taurocholic acid were added to Krebs. After 180 min of perfusion, livers perfused with solutions including 2% albumin (Group D, E) had a significantly higher release of hepatocellular and endothelial cell (purine nucleoside phosphorylase) enzymes and lower bile production as compared to Groups A, B, and C (P < 0.0001). Increasing levels of purine nucleoside phosphorylase (PNP), a reflection of damage to the microvascular endothelium preceded the increases in hepatocellular enzymes. Histologically, damages of sinusoidal endothelial cells and hepatocytes are appreciated moderate to severe in Groups D and E, slight to mild in Groups A and B, and not significant in Group C. These results suggest that BSA may have toxic effects to the perfused rat liver. These data also confirm that the IPRL modified for simultaneous perfusion of two livers is efficient, and that with this technique the rat liver can be optimally perfused for up to 3 hr with oxygenated Krebs Henseleit buffer without additives (Group B) and without blood. These two improvements should allow those performing studies with perfused rat livers to obtain data in a more efficient, accurate, and inexpensive fashion.
PMCID: PMC2952496  PMID: 1405604
4.  Magnetic resonance imaging of the optic nerve in extremes of gaze. Implications for the positioning of the globe for retrobulbar anaesthesia. 
Orbital magnetic resonance imaging was carried out in nine directions of gaze in a normal subject. The findings are presented and discussed especially in relation to retrobulbar injections. Atkinson's position is confirmed to be hazardous and a new position for the globe at retrobulbar injections is suggested.
PMCID: PMC504392  PMID: 1486074
5.  Life expectancy in keratoconus. 
It is observed that few patients over the age of 60 regularly attend the keratoconus clinic at Moorfields Eye Hospital. The hypothesis that patients with keratoconus have a shorter life expectancy owing to underlying connective tissue related disease was tested. From patient records a sample of 337 keratoconus patients aged at least 40 years by 1991 were identified, of which 279 were living, 13 were deceased, and 45 were untraceable. The mortality rate for keratoconus patients was compared with that of the general population using actuarial English life tables. Results show no significant difference between the general population mortality rate and that of the keratoconus sample even with adjustment for social class. Possible explanations for the non-attendance of older patients are discussed.
PMCID: PMC505224  PMID: 1420040
6.  Inhibition of astrocyte proliferation and binding to brain tissue of anticardiolipin antibodies purified from lupus serum. 
Annals of the Rheumatic Diseases  1992;51(6):707-712.
Polyclonal anticardiolipin antibodies purified from pooled serum samples of patients with systemic lupus erythematosus were shown to have inhibitory effects on cultured normal rat brain astrocytes (RBA-1 cells). Anticardiolipin antibodies at concentrations from 50 to 200 micrograms/ml inhibited the [3H]thymidine incorporation of RBA-1 cells in a dose dependent manner after three days of culture. A kinetic study showed that anticardiolipin antibodies (100 micrograms/ml) maximally inhibit the proliferation of RBA-1 cells (20.6 (5.1)% of the control value) after incubation for one day. In contrast, human gamma globulin (100 micrograms/ml) had no effect on these cells. In the presence of anticardiolipin antibodies (100 micrograms/ml), the RBA-1 cells attached to the bottom of wells became spherical and the expression of glial fibrillary acidic protein in the cytoplasm was slightly reduced. Using 3,3'-dihexyloxacarbocyanine iodide as an indicator, anticardiolipin antibodies depolarised the membrane potential of RBA-1 cells after one day of culture. In addition, the percentage binding of RBA-1 cells with anticardiolipin antibodies was greater than with gamma globulin as determined by flow cytometric analysis. Immunofluorescence staining of brain tissue from BALB/c mice with anticardiolipin antibodies was noted in the corpus callosum, the cellular zone near the corpus callosum, and cells scattered in brain tissue. These results suggest that anticardiolipin antibodies have an inhibitory effect on brain cells and elicit thrombus formation in brain vessels, which plays a part in neuropsychiatric lupus.
PMCID: PMC1004730  PMID: 1616350
7.  Epstein-Barr virus DNA in nasopharyngeal carcinomas from Chinese patients in Hong Kong. 
Journal of Clinical Pathology  1992;45(5):396-397.
AIMS: To investigate the presence of Epstein-Barr virus (EBV) in cases of nasopharyngeal carcinoma (NPC) in Chinese patients living in Hong Kong. METHODS: Nasopharyngeal biopsy specimens, formalin fixed and paraffin wax embedded, from 24 patients, eight with undifferentiated nasopharyngeal carcinoma, eight with well differentiated squamous carcinoma, and eight showing normal tissue histology, were analysed for the presence of Epstein-Barr virus (EBV) DNA by slot-blot hybridisation on extracted unamplified DNA, and also after amplification of EBV specific sequences by the polymerase chain reaction (PCR). RESULTS: DNA slot-blot analysis showed viral DNA in all the undifferentiated, five of the well differentiated tumours, and none of the normal biopsy specimens. PCR studies confirmed positivity in the eight undifferentiated tumours, but six of the well differentiated tumours and three of the normal biopsy specimens showed viral DNA by this method, illustrating its greater sensitivity. CONCLUSIONS: EBV genome is present in appreciable copy number in most cases of well differentiated NPC in Chinese patients in Hong Kong.
PMCID: PMC495299  PMID: 1317885
8.  Human papillomavirus 16/18 and nasopharyngeal carcinoma. 
Journal of Clinical Pathology  1992;45(1):81-82.
Sixteen cases of nasopharyngeal carcinoma (eight anaplastic and eight well differentiated squamous types) were examined for the presence of human papillomavirus types 16 and 18 genomes using the polymerase chain reaction on paraffin wax embedded biopsy specimens. Although nasopharyngeal carcinoma, particularly the anaplastic type, is strongly associated with Epstein-Barr virus, other factors may be involved in its pathogenesis. No DNA of either human papillomavirus subtype was detected. It is concluded, therefore, that these two "high risk" types of human papillomavirus are not implicated in the pathogenesis of nasopharyngeal carcinoma. The number of cases in this series was small, however, and further studies are warranted using fresh biopsy material and including other viral subtypes.
PMCID: PMC495829  PMID: 1311002
9.  Role of nitric oxide and guanosine 3',5'-cyclic monophosphate in mediating nonadrenergic, noncholinergic relaxation in guinea-pig pulmonary arteries. 
British Journal of Pharmacology  1992;107(3):861-866.
1. Nonadrenergic, noncholinergic (NANC) nerves mediate vasodilatation in guinea-pig pulmonary artery (PA) by both endothelium-dependent and endothelium-independent mechanisms. The transmitter(s) involved in the endothelium-independent pathway have not yet been identified. We have therefore investigated the possibility that nitric oxide (NO) and guanosine 3',5'-cyclic monophosphate (cyclic GMP) may mediate this neural vasodilator response in guinea-pig branch PA rings denuded of endothelium. 2. Electric field stimulation (EFS, 50 V, 0.2 ms) induced a frequency-dependent (1-24 Hz), tetrodotoxin-sensitive relaxation of the U44069-precontracted PA rings in the presence of adrenergic and cholinergic blockade. 3. The NO synthase inhibitors NG-monomethyl L-arginine (L-NMMA, 100 microM) and NG-nitro L-arginine methyl ester (L-NAME, 30 microM), and the guanylyl cyclase inhibitor methylene blue (5 microM) inhibited the EFS (16 Hz)-induced relaxation by 53 +/- 5, 74 +/- 9 and 82 +/- 9% respectively (n = 5-7, P < 0.01, compared with control rings). 4. Excess concentrations of L-, but not D-arginine (300 microM) completely reversed the inhibitory effect of L-NMMA. 5. The EFS-elicited relaxation (4 Hz) was potentiated by 1 microM zaprinast, a type V phosphodiesterase inhibitor which inhibits guanosine 3':5'-cyclic monophosphate (cyclic GMP) degradation, but was unaffected by 0.1 microM zardaverine, a type III/IV phosphodiesterase inhibitor which inhibits cyclic AMP degradation. 6. EFS (50 V, 0.2 ms, 16 Hz) induced a 3 fold increase in tissue cyclic GMP content, an action which was inhibited by L-NMMA (100 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1907763  PMID: 1335345
10.  Evidence that the apparent complexity of receptor antagonism by angiotensin II analogues is due to a reversible and syntopic action. 
British Journal of Pharmacology  1992;106(2):233-241.
1. The interactions between angiotensin II (AII), two non-peptide antagonists DuP 753 and IMI, and eight peptide analogues of AII were investigated on the rabbit isolated aorta assay. DuP 753 and IMI behaved as simple competitive antagonists (pKB values 8.4 and 6.8, respectively). To different degrees, all the AII-peptide analogue interactions failed to meet the basic criteria for simple competition. In addition to rightward shift, the most significant feature was a concentration-dependent saturable depression of the upper asymptote of the AII concentration-effect curves. 2. 'Washout' and combined dose-ratio analysis experiments, in which DuP 753 was used as a reference antagonist, indicated that the profile of peptide antagonism was solely due to a reversible and syntopic action at the AII receptor. 3. By use of an operational model of agonism (Black & Leff, 1983) as a starting point, it was possible to account for the data with a new model which describes reversible receptor occupancy and occupied receptor-determined, saturable reduction in the efficacy of AII. Model-fitting gave estimates of pKB values for the peptide analogues and agonist affinity and efficacy parameters for AII. 4. The model was successfully tested by applying it to qualitatively similar results obtained in a cross-tissue analysis on guinea-pig aorta, ileum and stomach. 5. A 'molecular' interpretation of the efficacy changes, based on the concepts of receptor internalisation and expression, is offered.
PMCID: PMC1907508  PMID: 1393259
11.  Developmental changes in endothelium-dependent pulmonary vasodilatation in pigs. 
British Journal of Pharmacology  1992;106(2):324-330.
1. We compared in vitro endothelium-dependent vasorelaxant responses to acetylcholine (ACh) and the endothelium-independent vasodilator response to sodium nitroprusside (SNP) in prostaglandin F2 alpha (PGF2 alpha)-precontracted muscular pulmonary arteries (PA) from pigs aged 5 min to 2 h (neonatal), 3-10 days, 3-8 weeks and adults. 2. In the pulmonary artery (PA) rings from neonatal animals, the vasodilator response to ACh was negligible. However, responses to ACh were present in all PA rings from older animals, being greatest at 3-10 days and then decreasing with age (P less than 0.001, ANOVA). ACh (30 microM) induced a 1 +/- 1%, 92 +/- 9%, 62 +/- 5% and 51 +/- 6% reduction of the PGF2 alpha-generated tension in neonatal, 3-10 days, 3-8 weeks and adult groups, respectively. 3. The relaxant response to SNP was present in the PA rings from all age groups and increased with age (P less than 0.001, ANOVA). SNP (1 microM)-induced relaxation was 55 +/- 9%, 73 +/- 7%, 97 +/- 5% and 93 +/- 6% in neonatal, 3-10 days, 3-8 week and adult groups, respectively. 4. Removal of the vascular endothelium abolished the relaxant response to ACh but had no effect on the response to SNP in any groups. 5. NG-monomethyl-L-arginine (30 microM), a nitric oxide synthesis inhibitor, inhibited the response to ACh but not to SNP. The lipoxygenase inhibitor, nordihydroguaiaretic acid, had no significant effect on responses to ACh or SNP in any group.(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1907512  PMID: 1393265
12.  The role of platelet-activating factor and peptidoleukotrienes in the vascular changes of rat passive anaphylaxis. 
British Journal of Pharmacology  1992;105(1):119-125.
1. The role of platelet-activating factor (PAF) and peptidoleukotrienes as putative mediators of some of the vascular changes triggered by antigen was investigated in rats passively sensitized with monoclonal anti-DNP (2,4-dinitrophenyl) IgE. 2. Lethal anaphylaxis with respiratory distress, systemic hypotension, detachment of the intestinal mucosa, leukopenia and extravasation of protein-rich plasma was observed after antigen challenge of rats sensitized with partially purified monoclonal IgE at concentrations of 15 mg protein kg-1. 3. Analysis of the peritoneal fluid obtained after i.v. challenge with DNP-BSA (bovine serum albumin) showed the presence of significant amounts of PAF (101 +/- 8 pg/rat), whereas this mediator was undetectable in control animals. Leukotriene D4 was the predominant peptidoleukotriene that could be recovered after antigen challenge, and showed an extremely high concentration (92 +2- 15 ng/rat) as compared to PAF levels. 4. Extravasation of protein-rich plasma was observed shortly after challenge and reached a maximum at 30 min. Treatment of animals with i.v. PCA 4248 (1-2 mg kg-1) and WEB 2086 (1 mg kg-1), two chemically unrelated compounds which are antagonists of the PAF-receptor, produced a significant reduction of the extravasation of protein-rich plasma. 5. The same degree of protection could be afforded by MK-886, an inhibitor of leukotriene biosynthesis. Combined treatment with WEB 2086 and MK-886 provided greater inhibition of protein-rich plasma extravasation than either compound alone. PCA 4248 was also found to inhibit in a dose-dependent manner the systemic hypotension observed upon DNP-BSA challenge.(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1908595  PMID: 1596674
13.  Acetylation of O-specific lipopolysaccharides from Shigella flexneri 3a and 2a occurs in Escherichia coli K-12 carrying cloned S. flexneri 3a and 2a rfb genes. 
Journal of Bacteriology  1992;174(23):7500-7508.
Most of the Shigella flexneri O-specific serotypes result from O-acetyl and/or glucosyl groups added to a common O-repeating unit of the lipopolysaccharide (LPS) molecule. The genes involved in acetylation and/or glucosylation of S. flexneri LPS are physically located on lysogenic bacteriophages, whereas the rfb cluster contains the biosynthesis genes for the common O-repeating unit (D.A.R. Simmons and E. Romanowska, J. Med. Microbiol. 23:289-302, 1987). Using a cosmid cloning strategy, we have cloned the rfb regions from S. flexneri 3a and 2a. Escherichia coli K-12 containing plasmids pYS1-5 (derived from S. flexneri 3a) and pEY5 (derived from S. flexneri 2a) expressed O-specific LPS which reacted immunologically with S. flexneri polyvalent O antiserum. However, O-specific LPS expressed in E. coli K-12 also reacted with group 6 antiserum, indicating the presence of O-acetyl groups attached to one of the rhamnose components of the O-repeating unit. This was confirmed by measuring the amounts of acetate released from purified LPS samples and also by the chemical removal of O-acetyl groups, which abolished group 6 reactivity. The O-acetylation phenotype was absent in an E. coli strain with an sbcB-his-rfb chromosomal deletion and could be restored upon conjugation of F' 129, which carries sequences corresponding to a portion of the deleted region. Our data demonstrate that E. coli K-12 strains possess a novel locus which directs the O acetylation of LPS and is located in the sbcB-rfb region of the chromosomal map.
PMCID: PMC207459  PMID: 1280255
14.  Verapamil ameliorates the clinical and pathological course of murine myocarditis. 
Journal of Clinical Investigation  1992;90(5):2022-2030.
The effects of the calcium channel blocking agent, verapamil, were studied in a murine model of viral myocarditis. Three groups of 8-wk-old DBA/2 mice (n = 25 each) were inoculated with 10 plaque-forming units of encephalomyocarditis virus and randomized to three treatment regimens. Group 1 mice received verapamil intraperitoneally (5 mg/kg per d) for 7 d before infection, followed by verapamil orally (mean dose of 3.5 mg/mouse per d) in drinking water during infection. Group 2 mice received only verapamil orally starting on day 4 after infection, coincident with peak viremia. Group 3 (infected control) received no verapamil in regular drinking water after viral inoculation. Additional control animals were studied in group 4 (n = 21), consisting of uninfected control animals receiving intraperitoneal and oral verapamil at doses identical to group 1, and in group 5 (n = 21), consisting of uninfected and untreated controls. Animals were randomly killed from each group (n = 7) at 7, 14, and 28 d after infection. Routine histology was performed blindly on an apical slice of each heart and semi-quantitatively graded for inflammation, necrosis, calcification, and fibrosis on a scale of 0-4. Digital planimetry was performed to measure the absolute and relative areas of inflammation and necrosis. The pretreated animals in group 1 showed marked reduction in inflammation and necrosis (score of 3.7 +/- 1.4 vs. 8.7 +/- 2.0 in group 3 on day 14, P < 0.05) and were indistinguishable from the posttreated group 2 mice (score of 4.0 +/- 1.5 vs. 8.7 +/- 2.0 in group 3 on day 14, P < 0.05). All the uninfected control animals (groups 4 and 5) showed no myocardial lesions whether treated with verapamil or not. Quantitative planimetry confirmed decreased inflammation and necrosis (2.0 +/- 3.3% in group 1 and 3.5 +/- 3.1% in group 2 vs. 21.9 +/- 22.6% in group 3 on day 14). Untreated infected hearts injected with liquid silicone rubber exhibited extensive areas of focal microvascular constriction and microaneurysm formation; verapamil treatment in either group 1 or 2 completely abolished these abnormalities, resembling uninfected controls in groups 4 or 5. We conclude that verapamil, whether given before infection or after peak viremia in an encephalomyocarditis model of murine myocarditis, significantly reduces the microvascular changes and myocardial necrosis, fibrosis, and calcification leading to cardiomyopathy. This suggests the potentially important role of calcium and microvascular spasm in the pathogenesis of viral myocarditis leading to dilated cardiomyopathy, and may have future therapeutic implications.
PMCID: PMC443266  PMID: 1331179
15.  Recombinant interleukin-6 protects mice against experimental bacterial infection. 
Infection and Immunity  1992;60(10):4402-4406.
Because of reports of high levels of interleukin-6 (IL-6) in patients during infection, we studied the role of IL-6 in experimental infection. Mice infected with the facultative intracellular pathogen Listeria monocytogenes displayed high levels of IL-6 in their sera and tissues, particularly the spleen, 1 to 3 days after infection. At this time, the IL-6 titers correlated with bacterial numbers in individual mice and in groups of mice given graded doses of Listeria organisms. However, the presence of IL-6 in serum declined after 4 days, even when a large initial dose of bacteria meant that bacterial numbers were still increasing at this time. Recombinant mouse IL-6 injected intraperitoneally before infection protected mice in a dose-dependent manner. It was effective when given 4 h before infection but not when administration was delayed for 24 h postinfection. It is therefore believed that IL-6 plays a role in early priming of the immune response to infection. Its exact function in this model is being investigated.
PMCID: PMC257478  PMID: 1398949
16.  Use of an oligonucleotide probe to detect Vibrio parahaemolyticus in artificially contaminated oysters. 
Applied and Environmental Microbiology  1992;58(10):3419-3422.
A 26-mer oligonucleotide specific to Vibrio parahaemolyticus was synthesized from a 1,275-bp thermostable direct hemolysin (tdh) gene. This oligonucleotide probe specifically reacted with DNA from 89 of 95 V. parahaemolyticus isolates but not with DNA from other vibrios or other enteric and nonenteric organisms (n = 48). The probe hybridized with Southern blots of 0.5-kb HindIII-restricted chromosomal DNA fragments from all but five V. parahaemolyticus test isolates. The probe could be used to directly identify V. parahaemolyticus in artificially contaminated food without an isolation step.
PMCID: PMC183116  PMID: 1444377
17.  Pharmacokinetics of 18F-labeled fleroxacin in rabbits with Escherichia coli infections, studied with positron emission tomography. 
Antimicrobial Agents and Chemotherapy  1992;36(10):2286-2292.
18F-labeled fleroxacin was used to measure the pharmacokinetics of fleroxacin in healthy and infected animals by positron emission tomography (PET) and tissue radioactivity measurements. In all experiments, a pharmacological dose of unlabeled drug (10 mg/kg) was coinjected with the tracer. The pharmacokinetics of [18F]fleroxacin was measured in groups of healthy mice (n = six per group) at 10, 30, 60, and 120 min after injection and in groups of rats with Escherichia coli thigh infections (n = six per group) at 60 and 120 min after injection by radioactivity measurements in excised tissues. In healthy rabbits (n = 4) and in rabbits with E. coli thigh infections (n = 4), tissue concentrations of drug were determined by serial PET imaging over 2 h; after the final image was acquired, animals were sacrificed and concentrations measured by PET were compared with the results of tissue radioactivity measurements. In all three species, there was rapid equilibration of [18F]fleroxacin to significant concentrations in most peripheral organs; low concentrations of drug were detected in the brain. Accumulations of radiolabeled drug in infected and healthy thigh muscles were similar. Peak concentrations of drug of more than three times the MIC for 90% of members of the family Enterobacteriaceae (greater than 100-fold for most organisms) were achieved in all tissues except brain and remained above this level for more than 2 h. Especially high peak concentrations were achieved in the kidney (greater than 75 micrograms/g), liver (greater than 50 micrograms/g), blood (greater than 25 micrograms/g), and bone and lung (greater than 10 micrograms/g).Since the MICs for 90% of all Enterobacteriaceae are <2 micrograms/ml, fleroxacin should be particularly useful in treating gram-negative infections affecting these tissues. In contrast, the low concentration of drug delivered to the brain should limit the toxicity of the drug for the central nervous system.
PMCID: PMC245491  PMID: 1444310
18.  Molecular characterization of the Zymomonas mobilis enolase (eno) gene. 
Journal of Bacteriology  1992;174(20):6548-6553.
The Zymomonas mobilis gene encoding enolase was cloned by genetic complementation of an Escherichia coli eno mutant. An enzyme assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the overexpression of enolase in E. coli clones carrying the Z. mobilis eno gene. The eno gene is present in a single copy of the Z. mobilis genome. Nucleotide sequence analysis of the eno region revealed an open reading frame of 1,293 bp that encodes a protein of 428 amino acids with a predicted molecular weight of 45,813. Comparison of the sequence of Z. mobilis enolase with primary amino acid sequences for other enolases indicates that the enzyme is highly conserved. Unlike all of the previously studied glycolytic genes from Z. mobilis that possess canonical ribosome binding sites, the eno gene is preceded by a modest Shine-Dalgarno sequence. The transcription initiation site was mapped by primer extension and found to be located within a 115-bp sequence that is 55.7% identical to a highly conserved consensus sequence found within the regulatory regions of highly expressed Z. mobilis genes. Northern RNA blot analysis revealed that eno is encoded on a 1.45-kb transcript. The half-life of the eno mRNA was determined to be 17.7 +/- 1.7 min, indicating that it is unusually stable. The abundance of the eno message is proposed to account for enolase being the most prevalent protein in Z. mobilis.
PMCID: PMC207621  PMID: 1400207
19.  Internal entry of ribosomes on a tricistronic mRNA encoded by infectious bronchitis virus. 
Journal of Virology  1992;66(10):6143-6154.
mRNA3 specified by the coronavirus infectious bronchitis virus appears to be functionally tricistronic, having the capacity to encode three small proteins (3a, 3b, and 3c) from separate open reading frames (ORFs). The mechanism by which this can occur was investigated through in vitro translation studies using synthetic mRNAs containing the 3a, 3b, and 3c ORFs, and the results suggest that translation of the most distal of the three ORFs, that for 3c, is mediated by an unconventional, cap-independent mechanism involving internal initiation. This conclusion is based on several observations. A synthetic mRNA whose peculiar 5' end structure prevents translation of the 5'-proximal ORFs (3a and 3b) directs the synthesis of 3c normally. Translation of 3c, unlike that of 3a and 3b, was insensitive to the presence of the 5' cap analog 7-methyl-GTP, and it was unaffected by alteration of the sequence contexts for initiation on the 3a and 3b ORFs. Finally, an mRNA in which the 3a/b/c infectious bronchitis virus coding region was placed downstream of the influenza A virus nucleocapsid protein gene directed the efficient synthesis of 3c as well as nucleocapsid protein, whereas initiation at 3a and 3b could not be detected. Expression of the 3c ORF from this mRNA, however, was abolished when the 3a and 3b coding region was deleted, indicating that 3c initiation is dependent on upstream sequence elements which together may serve as a ribosomal internal entry site similar to those described for picornaviruses.
PMCID: PMC241492  PMID: 1527853
20.  Mannose-induced dysmorphogenesis of metanephric kidney. Role of proteoglycans and adenosine triphosphate. 
Journal of Clinical Investigation  1992;90(4):1205-1218.
Because various fetal anomalies are seen in diabetic offspring, we examined the effects of sugars on proteoglycans (PGs): extracellular matrix (ECM) macromolecules modulating morphogenesis. 13-d-old mouse metanephric kidney explants were exposed to mannose for 7 d and labeled with [35S]sulfate, [35S]-methionine, or [3H]thymidine. Mannose exposure caused reduction in kidney size and disorganization of ureteric bud branches with inhibition of glomerulogenesis. Tissue autoradiographic and immunofluorescence studies indicated decreased expression of sulfated PGs in ECMs. Helix pomatia lectin binding to D-GalNAc residues of glomerular epithelial cells was also reduced. Biochemical studies revealed decreased synthesis of sulfated PGs. PGs were of lower molecular weight with reduced charge density and increased chondroitin/heparan sulfate ratio. Immunoprecipitation of [35S]methionine-labeled proteins confirmed the reduction of PG core peptides. Intracellular ATP levels were reduced. The addition of 0.1 mM ATP to culture media restored kidney size, the population of glomeruli, and the synthesis and characteristics of PGs to almost normal, with no detectable effect on the replication of cells as determined by [3H]thymidine incorporation. The effect of ATP could be partially blocked by the P2y-purinoreceptor, i.e., reactive blue-2. Data suggest that mannose causes energy depletion by cellular ATP consumption and thus selectively alters the synthesis of heavily glycosylated proteins with rapid turnover, such as PGs, resulting in renal dysmorphogenesis.
PMCID: PMC443161  PMID: 1401058
21.  Home care for the disabled elderly: predictors and expected costs. 
Health Services Research  1992;27(4):453-479.
While interest in publicly funded home care for the disabled elderly is keen, basic policy issues need to be addressed before an appropriate program can be adopted and financed. This article presents findings from a study in which the cost implications of anticipated behavioral responses (for example, caregiver substitution) are estimated. Using simulation techniques, the results demonstrate that anticipated behavioral responses would likely add between $1.8 and $2.7 billion (1990 dollars) to the costs of a public home care program. Results from a variety of cost simulations are presented. The data base for the study was the 1982 National Long-Term Care Survey.
PMCID: PMC1069889  PMID: 1399652
22.  Morphoregulatory activities of E-cadherin and beta-1 integrins in colorectal tumour cells. 
British Journal of Cancer  1992;66(4):629-634.
The cadherin family of adhesion molecules are prime mediators of cell-cell interactions while the integrins predominantly mediate cell-matrix and to a lesser extent cell-cell binding specificity. We have recently shown that a human colon carcinoma cell line (SW1222) organizes into glandular structures, with well defined polarity when cultured in three-dimensional type I collagen gel. The current study indicates that SW1222 cells display high levels of E-cadherin (E-cd, epithelial cadherin) by western blotting and immunohistochemical staining. A monoclonal antibody (HECD-1) specific for human E-cd blocks cell-cell adhesion (100%) and inhibits (up to 75%) the glandular differentiation of SW1222 cells growing in collagen gel. Furthermore the anti-beta 1 integrin monoclonal antibody (mAb13) inhibits the glandular differentiation of SW1222 cells (61%) and their cellular binding to type I collagen (60%). However, no significant inhibition of cell-cell adhesion was demonstrated using mAb13 nor the anti-carcinoembryonic antigen monoclonal antibody (PR3B10). These results are consistent with E-cd being a cell-cell adhesion molecule expressed by SW1222 cells. These data indicate that E-cd and beta 1 integrins mediate cell-cell and cell-collagen interactions required for the induction and maintenance of the glandular differentiation of colorectal tumour cells. Thus the down-regulation or loss of E-cd and beta 1 integrins seen in poorly differentiated colorectal tumours may represent one of the abnormalities underlying their progression towards an undifferentiated phenotype in vivo.
PMCID: PMC1977417  PMID: 1384639
23.  Early detection of antibody to human immunodeficiency virus type 1 by using an antigen conjugate immunoassay correlates with the presence of immunoglobulin M antibody. 
Journal of Clinical Microbiology  1992;30(9):2379-2384.
Sequential plasma samples obtained from 16 individuals who seroconverted were tested for the presence of antibody to human immunodeficiency virus type 1 (HIV-1) by an antigen conjugate enzyme immunoassay (EIA) and a conventional antibody conjugate assay. In 11 of these individuals, the antigen conjugate assay detected antibody to HIV-1 2 to 11 days (mean, 5.5 days) earlier than the antibody conjugate assay. In 11 individuals, HIV-1 p24 antigen was detected a median of 6.5 days (range, 3 to 14 days) prior to positivity by the antigen conjugate EIA. Using class-specific probes, we determined the profiles of immunoglobulin M (IgM), IgG, and IgA antibodies for each individual and correlated these profiles with the EIA signals from both assays. In general, the appearance of IgM exhibited a peak at about 1 week postseroconversion, which was followed by gradually declining levels. Absorbance levels for IgG antibody, however, rose steadily and reached a plateau after 3 to 5 weeks. The levels of IgA were generally low and variable. In contrast to the progressive increase in EIA absorbance observed by the antibody conjugate assay, the antigen conjugate assay displayed a rapid early rise in absorbance which generally coincided with the transient expression of IgM antibody. The subsequent gradual increase coincided with rising levels of IgG. Because the configuration of the antigen conjugate EIA allows for an increased sensitivity for IgM compared with that for other classes of immunoglobulins, these results suggest that earlier detection of antibody to HIV-1 is due to the detection of IgM antibody during the early phase of seroconversion.
PMCID: PMC265509  PMID: 1401002
24.  Cloning of an Erwinia herbicola gene necessary for gluconic acid production and enhanced mineral phosphate solubilization in Escherichia coli HB101: nucleotide sequence and probable involvement in biosynthesis of the coenzyme pyrroloquinoline quinone. 
Journal of Bacteriology  1992;174(18):5814-5819.
Escherichia coli is capable of synthesizing the apo-glucose dehydrogenase enzyme (GDH) but not the cofactor pyrroloquinoline quinone (PQQ), which is essential for formation of the holoenzyme. Therefore, in the absence of exogenous PQQ, E. coli does not produce gluconic acid. Evidence is presented to show that the expression of an Erwinia herbicola gene in E. coli HB101(pMCG898) resulted in the production of gluconic acid, which, in turn, implied PQQ biosynthesis. Transposon mutagenesis showed that the essential gene or locus was within a 1.8-kb region of a 4.5-kb insert of the plasmid pMCG898. This 1.8-kb region contained only one apparent open reading frame. In this paper, we present the nucleotide sequence of this open reading frame, a 1,134-bp DNA fragment coding for a protein with an M(r) of 42,160. The deduced sequence of this protein had a high degree of homology with that of gene III (M(r), 43,600) of a PQQ synthase gene complex from Acinetobacter calcoaceticus previously identified by Goosen et al. (J. Bacteriol. 171:447-455, 1989). In minicell analysis, pMCG898 encoded a protein with an M(r) of 41,000. These data indicate that E. coli HB101(pMCG898) produced the GDH-PQQ holoenzyme, which, in turn, catalyzed the oxidation of glucose to gluconic acid in the periplasmic space. As a result of the gluconic acid production, E. coli HB101(pMCG898) showed an enhanced mineral phosphate-solubilizing phenotype due to acid dissolution of the hydroxyapatite substrate.
PMCID: PMC207111  PMID: 1325965
25.  The cytoplasmic peptidoglycan precursor of vancomycin-resistant Enterococcus faecalis terminates in lactate. 
Journal of Bacteriology  1992;174(18):5982-5984.
Vancomycin resistance plasmids in enterococci carry the genes vanH and vanA, which encode enzymes catalyzing, respectively, the reduction of 2-keto acids to 2-D-hydroxy acids and the addition of D-hydroxy acids to D-alanine. It has therefore been postulated that resistant cells produce peptidoglycan precursors that terminate in the depsipeptide D-alanine-2-D-hydroxy acid rather than the dipeptide D-alanine-D-alanine, thus preventing vancomycin binding (M. Arthur, C. Molinas, T. D. H. Bugg, G. D. Wright, C. T. Walsh, and P. Courvalin, Antimicrob. Agents Chemother. 36:867-869, 1992). In the present work, a cytoplasmic peptidoglycan precursor was isolated from vancomycin-resistant Enterococcus faecalis and analyzed by mass spectrometry, which suggested the structure UDP-N-acetyl-muramyl-L-Ala-D-Glu-L-Lys-D-Ala-D-lactate.
PMCID: PMC207137  PMID: 1522072

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