Increased zidovudine prescribing associated with lamivudine availability.
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Antiviral Agents↗
Biomedical subjects
B Yip
Publications and source records attributed to B Yip.
Vasoactive effects of smoking as mediated through nicotinic stimulation of sympathetic nerve fibers.
Patients who smoke have higher complication rates than nonsmokers following many surgical procedures. It is not known if the adverse effects of smoking are caused by a nicotine effect or by some other potentially harmful agents that exist in tobacco smoke. It is also not known if these vasoactive effects are mediated through sympathetic nerve fibers (via nicotinic receptors in ganglia) or through elevated circulating levels of vasoactive hormones. We designed a 5-day protocol to measure relative blood flow both before and after a digital sympathetic block in the digits of subjects who were regular smokers following both smoking and wearing of a transdermal nicotine patch. Suitable pulse/wave tracings were recorded on 23 subjects. We also measured serum levels of nicotine, cotinine, vasopressin, norepinephrine, epinephrine, dopamine, and carboxyhemoglobin on each test day. Data for these serum levels were available in 30 test subjects. Digital sympathetic block had a significant beneficial effect in reversing the decreased digital blood flow that occurred after smoking (and also with use of the nicotine patch), despite the elevated circulating levels of vasopressin and norepinephrine seen with smoking. The vasoactive effects of smoking are probably due to the nicotinic effects on sympathetic fibers at the ganglionic levels.
Adult↗
The hemodynamic and hematologic effects of cigarette smoking versus a nicotine patch.
Patients who smoke have higher complication rates than nonsmokers in the postoperative period. The authors designed an experimental protocol for habitual smokers (n = 30) to determine the specific hemodynamic and hematologic adverse effects possibly caused by nicotine and whether the method of nicotine delivery and systemic nicotine levels achieved might influence these adverse effects. During the 5-day study, subjects were asked to refrain from smoking, and testing sessions were conducted as follows: on day 1, the subjects smoked two cigarettes immediately before testing; on day 3 (control day), testing was done after not smoking for 48 hours and then the subjects were instructed to wear a transdermal nicotine patch (PROSTEP 22 mg/day) for 24 hours and replace it with another so that, on day 5, testing took place after the subjects had worn the patch for approximately 34 hours. At each testing session, digital artery pulse amplitude and a number of clinical and serum blood level parameters were measured. Relative digital blood flow after smoking (69.2 +/- 5.8%) and with the patch (80.4 +/- 7.6%) was lower than on the control day (100.0 +/- 0.0%). The nicotine patch, unlike smoking, had no effect on vasopressin or fibrinogen concentrations, hematocrit, or white cell or platelet counts; both smoking and the patch resulted in elevated norepinephrine levels.
Administration, Cutaneous↗
DNA analysis of Huntington's disease in southern Chinese.
Allelic frequencies of RFLPs at loci closely linked to the HD gene, D4S95, D4S91, D4S141, and D4S90, were determined in 13 Huntington's disease (HD) patients from nine Chinese families and 129 normal subjects. These were similar for non-HD and HD chromosomes and the HD gene in Chinese is associated with multiple haplotypes. Hence the HD gene probably arose independently in the background haplotypes of the Chinese population. The heterozygosity rates for the two most useful RFLP sites are 0.659 for D4S95-AccI VNTR and 0.494 for D4S141-HindIII. (CAG)n repeat numbers ranged from 12 to 27 in 174 normal chromosomes. In 52 meiotic recombinations, the (CAG)n repeats were stably inherited in normal families. In HD families, 12 of 13 HD patients had expanded (CAG)n repeats of 40 to 58. Additionally, 10 asymptomatic family members had expanded (CAG)n repeats and the inheritance of the expanded repeat was unstable in these families.
Alleles↗
Uses of dinucleotide/trinucleotide repeats in the diagnosis of genetic diseases.
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Adolescent↗
Elderly patients and resuscitation. Nurses' and doctors' views may differ.
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Aged↗
Intragenic dinucleotide repeats in factor VIII gene for the diagnosis of haemophilia A.
Two multi-allelic microsatellite polymorphisms within the factor VIII gene were studied in 138 Chinese subjects. The allele sizes detected were higher than those found in Caucasian populations, whereas the heterozygosity rates were lower, being 0.5370 for intron 13 and 0.4444 for intron 22 repeats respectively. Their usefulness in diagnosis was compared to other intragenic and extragenic RFLPs, using previous data on the same 31 unrelated haemophilia A families. These intragenic microsatellite repeat polymorphisms were only informative for 18/31 families (58%); however, with the combined use of all existing RFLPs, the cumulative informativeness would be 100%.
Asian People↗
The relationship between micronutrient depletion and oral health in geriatrics.
Changes in the oral microbial flora, some of which are related to mucosal disease, have been detected in the elderly, but the causes are not fully understood. This study has examined the possible role of micronutrient depletions in the reduced colonisation resistance and oral infection exhibited by some elderly subjects. The oral health, oral microbiology and micronutrient status of 37 geriatric patients aged 65-91 years (mean 81 years) were examined. Ten of the patients had no oral mucosal disease. Mucosal pathology in the remainder included erythema (27%), denture stomatitis (24%), angular cheilitis (16%) and atrophic glossitis (41%). Those with mucosal pathology had significantly lower serum iron concentrations (P = 0.02). Serum or plasma concentrations of zinc, copper, selenium, C-reactive protein, transferrin, caeruloplasmin, albumin, vitamin A and vitamin E were not significantly different between those with oral disease and those with healthy mouths. Similarly, activity of the selenium-containing enzyme, red cell glutathione peroxidase, did not differ significantly between the two groups. In both groups, plasma selenium concentrations (82%), red cell glutathione peroxidase activity (47%), plasma zinc concentrations (58%) and albumin concentrations (44%) tended to be below the lower limit of the reference interval. The influence of subclinical infection on these values is discussed.
Aged↗
Do stroke units save lives?
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Cerebrovascular Disorders↗
Effects of cholestyramine and acipimox on subfractions of plasma low density lipoprotein. Studies in normolipidaemic and hypercholesterolaemic subjects.
Two independent studies were designed to investigate the separate and combined effects of acipimox and cholestyramine on plasma low density lipoprotein subfractions. In the first study, normolipidaemic subjects were given cholestyramine (16 g day-1, 4 weeks), followed, after an 8-week wash-out period, by acipimox (750mg day-1, 4 weeks). In the second study, moderately hypercholesterolaemic subjects were prescribed acipimox (1250mg day-1, 10 weeks), followed by acipimox in combination with low dose cholestyramine (12g day-1) for a further 10 weeks. In the normal subjects, cholestyramine decreased total LDL mass (density (d) = 1.019-1.063g ml-1) by selectively reducing the largest, least dense LDL-I (d 1.025-1.034 g ml-1, P less than 0.05) and LDL-II (d 1.034-1.044 g ml-1, P less than 0.005) subfractions. The small, dense LDL-III (d 1.044-1060 g ml-1) showed a variable response to the resin. In the same subjects acipimox produced no overall change in total LDL mass but showed a tendency to redistribute LDL towards LDL-I (+10%) and LDL-II (+10%) in a manner related to the changes in plasma triglyceride (TG) (TG vs. LDL-III r = 0.75, P less than 0.05). In the hypercholesterolaemic subjects acipimox induced a substantial redistribution of LDL subfractions (LDL-I +84% P less than 0.05; LDL-III -50%) without affecting total LDL mass. The addition of cholestyramine produced a significant decrease in total LDL mass which was again confined to the LDL-I (-28%) and LDL-II (-23%) subfractions.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Plasma triglyceride and low density lipoprotein metabolism.
This study examines the relationship between plasma triglyceride and low density lipoprotein (LDL) levels by measuring the turnover of the native and 1,2 cyclohexanedione-treated lipoprotein in 25 healthy adults. Plasma triglyceride showed a strong positive correlation with circulating LDL apoprotein (apo LDL) mass. In order to achieve a satisfactory fit to the kinetic data it was necessary to postulate the existence of two plasma apo LDL pools (A and B). When subjects were grouped in quintiles on the basis of circulating apo LDL mass, pool A predominated in those in the lowest quintile. The fractional catabolic rate (FCR) of apo LDL from this pool was high (FCR = 0.57 +/- 0.06 pools day-1). As plasma triglyceride and apo LDL mass rose, apoprotein accumulated in the more slowly metabolized pool B as a result of an increase in the rate of input of apo LDL into the latter. The fractional clearance rate of protein from this pool remained unchanged at 0.26 +/- 0.04 pools day-1. Synthesis of apo LDL into pool B correlated with plasma triglyceride (r = 0.553, P less than 0.01), suggesting that the protein in this pool was derived from large, triglyceride-rich very low density lipoprotein.
Adult↗
Molecular defects in haemophilia B: detection by direct restriction enzyme analysis.
The common restriction fragment length polymorphisms (RFLPs) associated with the FIX gene: 5' BamH I, Dde I, BamH I (2), Taq I and 3' Hha I were absent or of low incidence in Southern Chinese and are therefore not useful for linkage analysis. No deletion was detected amongst seven consecutive unrelated haemophilia B patients, but one had an insertion of a 15 kb Pvu II fragment containing exon d. Using an alternate strategy of polymerase chain reaction (PCR) amplification and direct sequencing, the molecular defect in the other six patients was defined. The four novel mutations characterized were: nucleotide (nt) 6410 G----C (Gly12----Ala); nt 31261 delta T (stop codon 31 bp downstream); nt 31260 C----G (Thr380----Ser) and nt 31122 C----A (Ala34----Asp). Two patients had the same mutation at nt 6365, G----A (Arg-4----Gln), identical to one previously described in other ethnic groups, suggesting that this is a hotspot for mutation. Each of the mutations was found to affect an enzyme recognition site and could thus be identified by direct visualization of abnormal restriction fragments in amplified genomic DNA. This allows rapid and accurate DNA diagnosis of haemophilia B in an ethnic group which otherwise shows little or no polymorphism for the common RFLP sites.
Blotting, Southern↗
Rapid isolation of low density lipoprotein (LDL) subfractions from plasma by density gradient ultracentrifugation.
High resolution density gradient ultracentrifugation (DGUC) and non-denaturing gradient gel electrophoresis (GGE) indicate that low density lipoprotein (LDL) in both normal and hyperlipidaemic subjects is composed of overlapping particle populations. A new centrifugation procedure has been developed which permits the separation of LDL subspecies directly from plasma within 24 h. The profiles obtained were analogous to those seen on gradient gel electrophoresis. LDL was divided into 3 fractions. The plasma concentration of LDL-I seen in young females was twice that in men (85.6 +/- 28.8 vs. 42.3 +/- 25.7 mg/dl, P less than 0.005). LDL-II was not significantly different in any group while LDL-III was specifically elevated in coronary artery disease (CAD) patients (207.1 +/- 92.6 mg/dl in CAD vs. 87.4 +/- 79.6 mg/dl in normal men, P less than 0.05). The presence of small, dense LDL detected either by density gradient centrifugation or gel electrophoresis was associated with raised triglyceride (TG) and low high density lipoprotein (HDL) cholesterol and may be a risk marker for coronary artery disease.
Adolescent↗
Serum gastrin level is increased by chronic hypercalcemia of parathyroid or nonparathyroid origin.
In patients with hypercalcemia with abdominal symptoms, gastrin concentration is often measured to exclude the Zollinger-Ellison syndrome. We found that interpretation of such measurements is clouded by a contradictory literature. We therefore measured serum gastrin concentrations in 78 patients with primary hyperparathyroidism, 36 with nonparathyroid hypercalcemia, 13 with hypocalcemia, and 33 normocalcemic controls. Gastrin values above normal occurred in 22% of those with primary hyperparathyroidism and 28% of those with nonparathyroid hypercalcemia. Values above 250 pg/mL occurred only in those with hypochlorhydria or multiple endocrine neoplasia, type 1 (MEN 1). After parathyroidectomy, gastrin levels fell significantly, but elevated values tended to recur in those with MEN 1 if hypercalcemia recurred. Thus, chronic hypercalcemia of either parathyroid or nonparathyroid origin may elevate serum gastrin concentrations, but marked elevations suggest either achlorhydria or MEN 1.
Adult↗
The kinetic mechanism of rat kidney gamma-glutamylcysteine synthetase.
A detailed kinetic investigation was made of the binding mechanism of gamma-glutamylcysteine synthetase purified from rat kidney. The results of initial rate and inhibition studies are consistent with a partially random mechanism in which ATP is the obligatory first substrate and both amino acids bind in a random order to the enzyme-ATP complex. Formation of the enzyme-substrate quaternary complex is necessary prior to release of products. This mechanism is consistent with previous binding studies with the enzyme and while it does not rule out participation of enzyme-bound gamma-glutamyl phosphate as an intermediate in catalysis, such an intermediate cannot be a discrete covalent complex.
Adenosine Diphosphate↗
Oral health in elderly patients.
A study of the oral health of elderly institutionalised patients and their oral care has revealed significant deficiencies, illustrating the need for a multi-disciplinary approach to oral health care centred on the development of mouth care regimens for nursing staff.
Aged↗