HIV-1-associated psychotic disorders.
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AIDS Dementia Complex↗
Biomedical subjects
B Ho
Publications and source records attributed to B Ho.
Perfluorochemical reperfusion limits myocardial reperfusion injury after prolonged hypothermic global ischemia.
The ability of an oxygenated perfluorochemical (Fluosol) to limit myocardial reperfusion injury following global hypothermic ischemic insult was investigated. Neonatal piglet hearts were arrested with cold crystalloid cardioplegia and stored for 12 hours in 2 degrees C saline. Reperfusion was carried out using an isolated, blood-perfused, working heart preparation. Hearts were initially reperfused (10 minutes) with either whole blood (WB, n = 6), unmodified perfluorochemical (PFC, n = 8), or aspartate/glutamate-enriched perfluorochemical cardioplegia (PFC+, n = 6), prior to institution of whole blood perfusion, functional evaluation and left ventricular biopsy. A control group (C, n = 7) was evaluated without an intervening period of ischemia. At a left ventricular diastolic pressure of 9 mm Hg WB hearts developed a left-ventricular stroke work index (SWI) of 3.8 +/- 2.3 x 10(3) erg/g (mean +/- standard error of the mean). Under similar conditions, PFC-reperfused hearts achieved a SWI of 14.6 +/- 1.3 x 10(3), significantly greater than that of WB (p less than 0.001). SWI for PFC+ hearts was 19.8 +/- 1.6 x 10(3), significantly increased over that of PFC (p less than 0.01), and not different from values obtained for C (19.2 +/- 0.8 x 10(3)). In addition, PFC-reperfused hearts demonstrated superior maintenance (p less than 0.05) of ATP (2.08 +/- 0.16 umole/g), compared to WB (1.50 +/- 0.19), while preservation of ATP in PFC+ hearts (2.99 +/- 0.12), was significantly increased over that of PFC (p less than 0.001), and not significantly different from that for C (2.68 +/- 0.17).(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphate↗
Successful long-term preservation of the neonatal heart with a modified intracellular solution.
UNLABELLED: Current methods of myocardial preservation for transplantation are suboptimal. A newly developed intracellular cardioplegic and storage solution (modified University of Wisconsin solution, group 1) was compared in a randomized, blinded fashion with our present clinical protocol, Stanford cardioplegic solution and saline storage (group 2) in an isolated neonatal pig model. After arrest and storage for 12 hours at 4 degrees C, biopsy specimens were taken from six group 1 hearts and five group 2 hearts for examination under an electron microscope and assessment of high-energy phosphate levels and water content. The remainder (group 1, n = 7; group 2, n = 6) were reperfused with blood for 50 minutes, after which function curves were obtained at left ventricular end-diastolic pressures of 3 to 12 mm Hg and biopsy tissue was taken. Eight control hearts (group 3) were cannulated in situ and perfused on the circuit without arrest or intervening ischemia. Stroke and minute work index curves were approximately threefold and fivefold higher for group 1 (modified University of Wisconsin solution) than for group 2 (Stanford), respectively (p less than 0.01). The hearts preserved with University of Wisconsin solution did not differ in function from unpreserved control hearts (group 3). High-energy phosphate levels were better maintained in group 1 than group 2 (p less than 0.05), and water content was lower (p less than 0.01). Semiquantitative grading of electron micrographs paralleled the functional and biochemical results. CONCLUSION: Modified University of Wisconsin intracellular solution provides markedly better heart preservation than conventionally used cardioplegic and storage solutions.
Adenosine↗
Further evaluation of children with elevated total cholesterol on screening.
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Adult↗
Comparison of culture and histology for the identification of Helicobacter pylori in endoscopic biopsies.
The aim of the study was to compare culture with microscopic examination of haematoxylin and eosin stained tissue sections in the identification of Helicobacter pylori in gastric antral mucosa. Duplicate gastric antral biopsies from 89 patients were cultured and examined histologically for H pylori. H pylori was cultured in 46 cases (51%) and identified histologically in 63 (71%). Results from the two tests concurred in 63 cases (71%). The presence of H pylori was strongly correlated with histological gastritis. Microscopic examination of haematoxylin and eosin stained tissue sections is therefore a reliable and convenient method of identifying H pylori.
Campylobacter↗
Inactivation of factor C by dimethyl sulfoxide inhibits coagulation of the Carcinoscorpius amoebocyte lysate.
The inhibition by dimethyl sulfoxide of the coagulation of the Carcinoscorpius Amoebocyte Lysate was found to be due to the inactivation of Factor C enzyme in the coagulation cascade and not due to the inactivation of proclotting enzyme as earlier reported in studies done on Limulus. Kinetic studies on both purified enzymes revealed that dimethyl sulfoxide completely but reversibly inhibited the activation of Factor C by endotoxins in a non-competitive manner whereas, it did not inhibit, albeit retard the activity of proclotting enzyme. This result also explains why clotting enzyme was shown to be largely unaffected by dimethyl sulfoxide.
Amino Acid Sequence↗
Cloning, characterisation and expression of vitellogenin gene of Oreochromis aureus (Teleostei, Cichlidae).
cDNA synthesised from liver Poly A+ RNA of estradiol-stimulated male Oreochromis aureus was ligated to PTZ-19R and transformed into E. coli. TG-1 to yield 6 x 10(4) clones/ug DNA, of which 6% was vitellogenin positive. Restriction maps indicate 4 possible subgroups of vitellogenin cDNA, with homology, observed by Southern hybridisation, at a fragment flanked by Pst 1 sites. When the amino acid sequence derived from the DNA sequence of pOA Vg 62 was aligned with that of S. gairdneri, X. laevis, C. elegans and D. melanogaster, homologies of 63%, 22%, 21% and 15%, respectively, were obtained. Estradiol induced a vitellogenin gene transcript of 6500 nucleotides at 6 h and reached a maximum at 72 h after stimulation.
Amino Acid Sequence↗
Effect of fish-fat or beef-fat supplemented diet on immune complex-induced enteropathy in the rat.
In contrast to animals on a beef fat-supplemented diet (BFD), animals maintained on a fish fat-supplemented diet (FFD) incorporate increased amounts of eicosapentaenoic acid (EPA) into membrane phospholipids. Generation of lipid mediators from such tissues favors the formation of compounds with less pro-inflammatory activity than are derived from tissues poor in EPA. Nevertheless, the FFD has not had a uniformly beneficial effect on animal models of inflammatory diseases. We previously showed that intravenous injection of rat anti-BSA-BSA complexes (IC) prepared in 5x antigen excess rapidly induced a striate pattern of serosal (to mucosal) hemorrhage and vascular congestion throughout the small intestine. In this study, we tested the effect of a BFD and FFD on immune complex-induced enteropathy. After six (Expt. 1) or eight weeks (Expt. 2) on the diet, rats were injected with IC and the severity of serosal hyperemia in the small intestine was scored. In some FFD, no lesions were seen under conditions which elicited moderate to severe lesions in BFD rats. In Expt. 1 involving 22 rats and in Expt. 2 involving 28 rats, those on the FFD had a significantly lower composite lesional score compared to those on the BFD, p less than 0.005 and p less than 0.005, respectively. These results indicate that the FFD had a beneficial effect on IC-induced enteropathy. It is suggested that this effect of the FFD may be mediated primarily by a reduction in availability of platelet-activating factor.
Animals↗
Biotyping of Campylobacter pylori.
Ninety-one biochemical tests were done on each of 50 strains of Campylobacter pylori isolated from the gastric mucosa of patients with gastritis and peptic ulcers in Singapore. The API ZYM system distinguished three biotypes of C. pylori. The organism was found to be biochemically different from C. jejuni and C. coli. We propose a biochemical identification kit that would be of use in identifying and differentiating biotypes of C. pylori, and would distinguish them from C. jejuni and C. coli.
Bacterial Typing Techniques↗
Campylobacter pylori: its association with active chronic gastritis.
C. pylori is a gram negative spiral bacteria that has been found to be associated with active chronic gastritis and duodenal ulcer. It possesses 4 to 6 sheathed flagella and has cockscrew motility. It is differentiated into 3 main morphological cell types during its cell cycle: spiral, straight rods and coccoid forms. It grows well in enriched media supplemented with sera in the presence of carbon dioxide at 35-37 degrees C. It is a high urease producer, non-sacchrolytic and possesses an array of other enzymes. Based on its biochemical characteristics, 3 biotypes have been proposed. It colonises the gastric mucosa of the antrum but is rarely found in normal antral mucosa. The serum urea probably helps its survival capability in the acidic microenvironment of gastric mucosa. It is sensitive to anti-ulcer medication and relatively insensitive to cimetidine. It is susceptible to a wide range of antimicrobials but resistant to vancomycin. The ability to grow the organism in a continuous culture system will shed more information about C. pylori.
Campylobacter↗
The fate of nitroguanidine in the rat.
The metabolism and disposition of nitroguanidine (NG), a component of military propellants and munitions, were examined in the rat. Radiolabeled nitroguanidine [( 14C]NG) was administered orally at doses of 20 and 200 mg/kg and intravenously at a dose of 20 mg/kg. Regardless of the route of administration, the radiolabel was recovered quantitatively in the urine of all animals within 48 hr after dosing. Chromatographic analysis of the urine indicated that the [14C]NG was excreted unchanged; no radiolabel was found in the expired air, feces, or tissues of the treated animals. No sex differences were seen in the disposition of NG. The kinetics of [14C]NG in the blood of the dosed animals was followed. The elimination half-life of NG was on the order of 2 hr. The bioavailability of orally administered NG was 100%; the kinetics of NG in the blood was not dose dependent. Examination of tissues 1 hr after an oral dose of NG showed that NG was evenly distributed throughout the body. Nitroguanidine is a chemical of low toxicity (LD50 greater than 5 g/kg); it is quantitatively absorbed from the gastrointestinal tract, distributed throughout the body, and rapidly excreted in the urine.
Animals↗
Single dose oral norfloxacin or intramuscular spectinomycin to treat gonorrhoea (PPNG and non-PPNG infections): analysis of efficacy and patient preference.
Norfloxacin, a new oral quinolone, was compared with intramuscular spectinomycin for treating culture proved gonorrhoea (caused by penicillinase producing strains of Neisseria gonorrhoeae (PPNG) and non-PPNG strains. A total of 547 infected men and women were randomly allocated to treatment with either single dose norfloxacin (800 mg by mouth) or spectinomycin (2 g intramuscularly). Patient preference for tablets or injections was noted at this visit. Patients returned four to eight days later for assessment of efficacy, safety, and preference. Of the 482 patients who attended follow up, all those treated with norfloxacin (94 infected with PPNG strains, 145 with non-PPNG strains) and all 82 infected with PPNG strains and treated with spectinomycin were cured. Of 161 infected with non-PPNG strains and treated with spectinomycin, 159 (99%) were cured. Side effects (headache, nausea, and sleepiness) occurred in three patients receiving norfloxacin and in 17 (16 pain at injection site, 1 giddiness) receiving spectinomycin. Most patients preferred tablets to injection both on day 1 (313 v 200) and at follow up (373 v 104). This study showed that norfloxacin was a highly effective alternative to spectinomycin, produced fewer side effects, and was the preferred mode of administration.
Administration, Oral↗
Effects of buprenorphine, methadone and naloxone on acquisition of behavioral chains.
Buprenorphine, methadone and naloxone were administered to pigeons key pecking under a repeated acquisition procedure. Under this procedure subjects are required to emit a new sequence of responses each session to receive access to food. All three drugs reduced overall key pecking rates although naloxone's rate-reducing effect was limited to the highest dose (30 mg/kg). The dose-effect curves for overall key pecking rate under buprenorphine and methadone were similar though the effective dose range for buprenorphine appeared wider. Methadone increased percentage of total errors at the highest doses, but neither buprenorphine nor naloxone affected total error levels very much. Within-session errors were increased early in the session under high methadone doses. Low buprenorphine doses also showed some tendency to increase errors early in the session. Buprenorphine and methadone reduced the number of chains completed in a dose-dependent manner. Buprenorphine was also administered daily at the most behaviorally disruptive dose (10 mg/kg/day). Under this dosing schedule, the behavior-suppressing effects of buprenorphine returned to base-line levels within 4 days. Error rates were unaffected by daily buprenorphine administration.
Animals↗
Pokeweed mitogen stimulates DNA synthesis in cultured amoebocytes of Carcinoscorpius rotundicauda.
Cultures of Carcinoscorpius rotundicauda amoebocytes in Grace's insect (modified) medium supplemented with 20% foetal bovine serum, were stimulated with pokeweed mitogen at 0.5 to 50 micrograms/ml for 24 to 72 h at 26 degrees C. DNA synthesis was monitored by measuring the uptake of 3H-thymidine. The optimal concentration of pokeweed mitogen was established at 2.5 micrograms/ml. The ideal duration of stimulation was 48 h. Under these conditions, amoebocyte cultures showed increases in uptake of 3H-thymidine up to 55-fold. Attempts at stimulation of these amoebocytes with phytohaemagglutinin, concanavalin A and endotoxin showed no increase in 3H-thymidine uptake. Nevertheless, positive stimulation by pokeweed mitogen demonstrates the potential of such an approach to establishing a permanent amoebocyte cell line for lysate production. This stimulation was reversed by 5 mM hydroxyurea, suggesting a true induction of DNA synthesis.
Amoeba↗
Inter- and intramolecular deuterium isotope effects on the cytochrome P-450-catalyzed oxidative dehalogenation of 1,1,2,2-tetrachloroethane.
The oxidation of 1,1,2,2-tetrachloroethane to dichloroacetic acid was investigated with rat liver microsomes and purified cytochrome P-450. Deuterium substitution had no effect on Km values, but both the inter- and intramolecular isotope effects (kH/kD) on Vmax were in the range 5.7-6.1. The equivalence of the inter- and intramolecular values indicates that 6.0 may be a good estimate of the intrinsic isotope effect. The intermolecular kH/kD value for the conversion of 1,1,2,2-trichloroethane and its 1-2H analog to chloroacetic acid was 5.5. These data, and the finding that 1 atom of 18O was incorporated into the product when TCEA was oxidized in an 18O2 atmosphere, support an oxidative dechlorination mechanism that involves hydrogen atom abstraction by the P-450 intermediate oxo complex.
Animals↗
Simultaneous determination of prednisolone acetate, prednisolone, prednisone, cortisone and hydrocortisone in swine plasma using solid-phase and liquid-liquid extraction techniques.
A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of prednisolone acetate (PA), prednisolone (PO), prednisone (PN), cortisone and hydrocortisone in swine plasma is described. Extraction of the steroid mixture from swine plasma with dexamethasone as internal standard was accomplished by solid-phase extraction (SPE) or the more traditional liquid-liquid extraction (LLE) techniques. These compounds were analyzed by normal-phase HPLC with ultraviolet detection. Although a detectable sensitivity of 5 ng/ml is achieved by the SPE technique, the practical sensitivity is established as 10 ng/ml. Conversely, the practical sensitivity is 5 ng/ml for all compounds by the LLE technique. Calibration curves were found to be linear between 10 and 500 ng/ml by the SPE technique and between 5 and 100 ng/ml by the LLE technique. The average recovery of the steroids PA, PO and PN at 20 ng/ml is between 70 and 90%. PA is stable for up to 3 h in swine plasma at room temperature (22 degrees C) but is completely converted to PO within 24 h. PA is stable in swine plasma in an ice bath for over 24 h. The usefulness of this analytical technique is demonstrated by the intraperitoneal administration of 125 mg of PA to swine and the quantitative determination of PA, PO and PN in the plasma as a function of time.
Animals↗
Bacterial and mycotic otological infections in Singapore.
This paper describes a microbiological study of 84 young adult men with clinical otitic infections. Gram-negative aerobic bacilli were frequently isolated from these patients diagnosed as having otitis externa or chronic suppurative otitis media, of which Pseudomonas species predominated. Staphylococcus aureus, S. epidermidis and aerobic Corynebacterium species (diphtheroids) were also found. About 40% of ear infections were attributed to otomycoses, chiefly from Aspergillus species and Candida parapsilosis. Antimicrobial susceptibility testing of the bacterial isolates revealed that Pseudomonas species were generally resistant to antibiotics commonly employed in general practice: ampicillin, erythromycin, co-trimoxazole, tetracycline and cephaloridine. However, polymyxin B, gentamicin and neomycin were active against some Pseudomonas isolates. Other Gram-negative bacilli were also mainly sensitive to gentamicin, neomycin as well as co-trimoxazole. Disc diffusion and minimum inhibitory concentration studies demonstrated good activity of ceftazidime, cefoperazone, tobramycin and carbenicillin against strains of Pseudomonas species and other Gram-negative rods. Cefotaxime and cefoxitin were active against Gram-negative bacilli other than Pseudomonas species. Beta-lactamase production did not appear to be the main mechanism of resistance in these community-acquired Gram-negative bacillary isolates. The antimicrobial therapy of otological infections is reviewed.
Adult↗
Patterns of infection in oncology patients in Singapore.
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Adolescent↗