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Biomedical subjects

C M Yu

Publications and source records attributed to C M Yu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Heparin therapy in the Chinese--lower doses are required.

Warfarin requirements are lower in the Chinese, but it is not known if this applies to heparin. We investigated the optimal dose for heparin therapy in Chinese patients, and to assess relationship between i.v. heparin dosage and anticoagulation efficacy. One hundred Chinese patients requiring intravenous heparin therapy were given an initial bolus followed by continuous intravenous infusion. The main outcome measures were: (i) Efficacy of anticoagulation assessed by blood coagulation studies (APTT) compared to heparin dosage, (ii) Determinants of dosage variation-age, gender, body weight, height, indication for heparin therapy and number of medications, other disease, and serum albumin level. It was found that the mean therapeutic infusion dose requirement of heparin was 848.7 +/- 274.7 units/h, 79% required a dose of 1000 units/h or less. Heparin dose correlated negatively with age (r = -0.40; p < 0.001) and positively with weight (r = 0.44 p < 0.001) and height (r = 0.49; p < 0.001). Chinese subjects require lower heparin doses (about 800 units/h) than usually recommended for Caucasians (usual dose 1000-1500 units/h). This can be partly explained by the lower body weight in Chinese patients.

Adult↗
PubMed1997

Spontaneous growth in Chinese patients with Turner's syndrome and influence of karyotype.

The pretreatment mixed cross-sectional and longitudinal height measurements of 203 patients with Turner's syndrome (TS) were analysed. Only one observation was included per year per child and a total of 858 observations formed the basis of the growth study. The mean and SD values were fitted separately by a second-degree polynomial function, giving smoothed growth curves. The spontaneous growth pattern of Chinese girls with TS runs parallel to published Caucasian TS growth curves. The mean final height of Chinese patients with TS was 142 cm compared to 147 cm and 139 cm observed in Northern European and Japanese patients, respectively. Patients with the 46, X, i(Xq) karyotype were found to be significantly shorter, whereas children with the 45, X/46, XY and 46, X, del(Xq) karyotypes were significantly taller among this group of patients. Patients with TS who were disomic for Xp are significantly taller than patients who were monosomic for Xp. Our results suggest that karyotype can have a significant effect on the growth of children with TS.

Adolescent↗
PubMed1996

Lack of association between insertion/deletion polymorphism of the angiotensin-converting enzyme gene and end-stage heart failure due to ischemic or idiopathic dilate cardiomyopathy in the Chinese.

Homozygosity for the deletion allele of the angiotensin-converting enzyme gene (DD) has been associated with a variety of cardiovascular diseases, including ischemic and idiopathic dilated cardiomyopathy, in Caucasians. In this study of 104 Chinese patients with end-stage heart failure due to idiopathic dilated or ischemic cardiomyopathy, the DD genotype frequency was low (12% and 11%, respectively) and was not seen more often than in a control group of 183 subjects without cardiac disease (13%). Therefore, in the Chinese, the DD genotype is less common than in Caucasians and does not appear to be associated with the development of either ischemic or idiopathic dilated cardiomyopathy.

Adult↗
PubMed1996

Right ventricular diastolic dysfunction in heart failure.

BACKGROUND: Left ventricular (LV) diastolic dysfunction is common in heart failure and is an important predictor of prognosis and mortality. Less attention has been paid to right ventricular (RV) diastolic function. In this study, we compared RV diastolic function in a large cohort of patients with heart failure (HF) with two groups: patients with pulmonary hypertension and normal LV function (the PHT group) and normal subjects. METHODS AND RESULTS: Transtricuspid and pulmonary artery flow were assessed by two-dimensional Doppler echocardiography at maximum inspiration and expiration in 185 subjects: 114 symptomatic HF patients (ejection fraction < 0.5), 31 PHT patients (pulmonary artery systolic pressure > 40 mm Hg), and 40 normal subjects. A subset was matched for age and heart rate. The results showed a high prevalence of RV diastolic abnormalities: HF patients had lower tricuspid E-A ratios, lower peak E-wave velocity, and prolonged RV isovolumic relaxation time (all P< .0001). Tricuspid E-wave deceleration time was significantly shorter only in those who had an LV restrictive filling pattern. The PHT group had similar findings. Compared with a normal range, more than half of the patients had lower tricuspid E-A ratios (HF, 55%; PHT, 69%), and 61% of HF and 58% of PHT patients had a prolonged RV isovolumic relaxation time. In the PHT group, RV diastolic parameters (E-wave deceleration time, E-A ratio, and isovolumic relaxation time) correlated significantly with pulmonary artery systolic pressure (P< .05). In the HF group, however, only tricuspid E-wave deceleration time correlated significantly with pulmonary artery systolic pressure, and HF patients with normal pulmonary artery systolic pressures had significantly lower tricuspid E-A ratios and prolonged RV isovolumic relaxation times compared with normal subjects. A close correlation existed between individual RV and LV diastolic parameters, suggesting that LV diastolic dysfunction may directly affect RV function, but there was no relation between LV size or systolic function and RV diastolic dysfunction. CONCLUSIONS: RV diastolic function is frequently abnormal in HF patients, and this is not related to elevated pulmonary artery systolic pressure alone, although high pulmonary artery pressure by itself also is associated with impaired RV diastolic function. Assessment of the role of right ventricular diastolic function in determining the symptoms and prognosis of heart failure is warranted.

Diastole↗
PubMed1996

Dilated cardiomyopathy in Noonan's syndrome.

Hypertrophic cardiomyopathy, with myocardial fibre disarray, may occur in 20-25% of cases with Noonan's syndrome. However, dilated cardiomyopathy has not previously been reported. We describe a patient with Noonan's syndrome who presented with typical features of dilated cardiomyopathy with biventricular enlargement and left ventricular ejection fraction of 0.16. Endomyocardial biopsy showed focal interstitial fibrosis and fibre hypertrophy but no disarray. This is the first report in the world literature of an association between Noonan's syndrome and dilated cardiomyopathy. It is possible that this linkage with dilated rather than hypertrophic cardiomyopathy is more common in the Chinese.

Adult↗
PubMed1996

Quantitative comparison in vitro of mutational antibiotic resistance of Enterobacter spp. using a spiral plater.

The presence of spontaneous mutational antibiotic resistance among 18 bacteremic isolates of Enterobacter spp. to cefotaxime, ceftazidime, gentamicin, amikacin, ciprofloxacin, and trimethoprim-sulfamethoxazole was determined quantitatively in vitro using a spiral plater. Each drug was delivered using the device and the agar plates were inoculated in radial streaks. The degree of resistance was estimated by dividing the antimicrobial concentration required to inhibit 90% of the colonies growing in the area beyond the MIC by the MIC itself. The degree of resistance to third-generation cephalosporins and aztreonam was statistically significantly greater than that to co-trimoxazole, imipenem, and ciprofloxacin (P < 0.01); the latter three antibiotics showed virtually no mutational resistance. An intermediate level of resistance was induced by aminoglycosides, and mutational resistance to piperacillin varied between this and the higher levels observed for the cephalosporins. By providing a simple and efficient means of detecting spontaneous mutational resistance, the spiral plater may prove useful in identifying those antimicrobial agents which induce few or no mutants and therefore may be more likely to be successful in treating infections due to Enterobacter spp.

Bacteriological Techniques↗
PubMed1996

Diastolic dysfunction and natriuretic peptides in systolic heart failure. Higher ANP and BNP levels are associated with the restrictive filling pattern.

BACKGROUND: Left ventricular diastolic dysfunction is common in patients with systolic heart failure and the restrictive type of filling pattern appears to be associated with increased cardiac mortality. Both artrial and brain (or ventricular) natriuretic peptides are also proven markers of the severity of heart failure. The aim of this study was to determine in a large cohort of patients with systolic heart failure whether diastolic abnormalities, and in particular the restrictive filling pattern of transmitral flow velocity, correlate with plasma atrial and brain natriuretic peptide levels. METHODS: Sixty-eight consecutive patients with symptomatic systolic heart failure (ejection fraction < 0.5) underwent two-dimensional Doppler echocardiography of left ventricular systolic and diastolic function, together with measurement of atrial and brain natriuretic peptides. RESULTS: The restrictive filling pattern was present in 62%, the abnormal relaxation pattern in 31% and only 7% were normal. Atrial and brain natriuretic peptide (ANP/BNP) levels were significantly higher in the restrictive compared to the abnormal relaxation group (ANP: 202.2 +/- 31.7 vs 102.5 +/- 22.1 pg.ml-1, P = 0.012; BNP: 277.8 +/- 27.7 vs 162.4 +/- 21.9 pg.ml-1, P = 0.002). In addition, a restrictive filling pattern was associated with lower ejection fractions (P = 0.026), higher pulmonary artery systolic pressure (P < 0.001), larger left atrial size (P = 0.044), and were more likely to be in New York Heart Association class III or IV than those with an abnormal relaxation pattern (P = 0.007). Both atrial and brain natriuretic peptides correlated inversely with ejection fraction (P < 0.001), fractional shortening (P < 0.001), and positively with pulmonary artery pressure (P = 0.004 and 0.001 respectively). There were no significant correlations between single diastolic parameters and atrial or brain natriuretic peptide levels for the total patient group except between mitral peak A wave velocity and brain natriuretic peptides (r = -0.3, P = 0.01). For those with abnormal relaxation pattern mitral, valve E-wave deceleration time correlated significantly with both atrial and brain natriuretic peptide levels (P < 0.01). CONCLUSIONS: This study confirms that the restrictive filling pattern of transmitral flow velocity is a marker of more severe heart failure, as indicated by its association with higher atrial and brain natriuretic peptide levels, lower ejection fraction and higher pulmonary artery pressure. Thus, this easily obtained Doppler-derived marker of diastolic dysfunction is useful for identifying those patients with more severe heart failure.

Aged↗
PubMed1996

Utilization of iron sources and its possible roles in the pathogenesis of Vibrio parahaemolyticus.

Vibrio parahaemolyticus is an important enteropathogen in Japan, Taiwan and other coastal regions. The influence of the regulation of iron on the pathogenesis of this pathogen has not been well characterized. The growth of pathogenic and non-pathogenic strains of V. parahaemolyticus on iron-limited agar plates was stimulated by ferritin, lactoferrin and transferrin at 30 microM, and also by hemin, hemoglobin and ferric ammonium citrate at 100 microM. Spontaneous iron-utilizing mutant strains (mutants) were derived from a clinical strain, ST550. Compared with the parent strain, lowered virulence was demonstrated for these mutants, as assayed by adult mouse and suckling mouse models. The in vivo growth and enterotoxigenicity of these mutants were also lower in the suckling mice. Adherence of the mutants to excised mouse intestine was lower as demonstrated by scanning electron microscopy. The iron-regulated outer membrane protein profile also changed in selected mutants. These results indicate that iron-regulated outer membrane proteins and other unknown factors associated with iron utilization may have profound influences, besides iron acquisition, on the pathogenesis of V. parahaemolyticus.

Animals↗
PubMed1995

Scrub typhus pneumonitis with delayed resolution.

A 35-year-old lady was admitted to hospital with fever and dry cough. Chest radiograph showed bilateral basal infiltrate. Her Weil-Felix test was strongly positive (OX-K > 1:160) and her fever came down with intravenous tetracycline. There was no improvement in the lung shadow and spirometry showed a severe restrictive defect. Open lung biopsy confirmed the diagnosis of interstitial pneumonitis. CT of thorax 6 months after presentation showed partial resolution of the interstitial shadow.

Adult↗
PubMed1995

Characterization of the manganese-resistant mutants derived from Vibrio parahaemolyticus.

The virulence and some related factors of Vibrio parahaemolyticus are regulated by the level of iron. In this study, five Mn-resistant mutants were selected after N-methyl-N'-nitrosoguanidine treatment and two transfers in medium containing high levels of manganese chloride. Production of siderophores and the 77-kDa iron-regulated outer-membrane protein and the bacterial growth in these Mn-resistants were deregulated, as compared with the wild-type strain. In addition, the regulation of these phenomena was partially or completely restored by the introduction of Escherichia coli fur gene. Also, the total cellular protein profiles of the wild-type and mutants showed that production of some proteins were positively or negatively regulated by iron, and expression of some of these proteins remained unaffected in these mutants. These results suggested the presence of a complicated iron regulation system, similar to the Fur system of E. coli, in this pathogen.

Bacterial Outer Membrane Proteins↗
PubMed1994

Recurrent syncope and quadriplegia.

A 72-year-old man had posturally induced syncopal episodes, followed by quadriparesis, coma, and death. Neuroimaging studies supported the clinical diagnosis confirmed by neuropathological findings.

Aged↗
PubMed1994

Drug overdosage and other poisoning in Hong Kong--the Prince of Wales Hospital (Shatin) experience.

From 1988 to 1991, 732 patients (91.1% Chinese) were admitted to four general medical wards at the Prince of Wales Hospital in Hong Kong with acute poisoning. The patients were predominantly female (68.9%) and relatively young (86.3% below the age of 40). Further analysis of 655 patients indicates that the vast majority of patients (96%) were admitted after self-poisoning with drugs or chemicals while 4% of cases were due to accidental poisoning. The main agents used by the former group included hypnotics/sedatives (33.1%), household products (15.7%), and analgesics (13.7%). There were nine deaths (1.4%). When compared to other Western countries, two important variations in the pattern of acute poisoning were seen. A substantial proportion of drugs ingested by our patients were not precisely identified. 'Dettol', a household product, was commonly used for self-poisoning in Hong Kong. Territory-wide studies of longer duration are needed to provide the physicians in Hong Kong with much needed information on the incidence and the pattern of acute poisoning.

Adolescent↗
PubMed1992

Microbiology, infection control, immunizations, and infectious disease exposure: education and practices in United States nursing schools.

BACKGROUND: Previous data suggest that nursing students in the United States are inadequately protected against hepatitis B. This survey focused on the immunization and education practices, infection control knowledge, and follow-up to infectious disease exposure by U.S. nursing schools. METHODS: To ascertain education requirements, immunization practices, and infectious disease postexposure follow up, a survey was sent to the director or dean of 1164 U.S. nursing schools. RESULTS: Seven hundred sixty-five schools (65.7%) responded to the survey. A microbiology course was required before clinical experience by 49% of schools. Clinical experience in the operating room was given by 16%, 65% of schools offered infectious and communicable disease courses, and 98% offered universal precaution instructions. The hepatitis B vaccine was required by 11%; 2% required yearly influenza vaccination. In a comparison of programs, the diploma schools were more likely to have written policies for infectious disease exposure follow-up and to use appropriate agencies for exposure follow-up (p = 0.0001). CONCLUSIONS: A microbiology course before clinical experience should be encouraged. Immunization policies and infectious disease exposure follow-up are currently inadequate in U.S. associate degree and baccalaureate nursing programs.

Curriculum↗
PubMed1992

Entering first-year residents' experiences and knowledge of infection control of hepatitis B and HIV, at five university-affiliated hospitals.

In 1990, the authors surveyed 149 entering first-year residents at five university-affiliated hospitals concerning the residents' experiences and knowledge of infection control. Sixty residents (40%) had experienced a needlestick injury during medical school, but only 35 of these residents (58%) had reported the mishap. One hundred thirty-nine residents (93%) had received the hepatitis B vaccine. Of those 60 who had experienced a needlestick injury, 57 (95%) had received the vaccine. Of the 149 residents, 111 (74%) reported having received instructions in universal precautions, as advocated by the Centers for Disease Control. There was a trend for residents who had received the vaccine also to have been instructed in universal precautions. Regarding the residents' knowledge of infection control, there was no statistically significant difference between the responses of those who had been instructed in universal precautions and those who had not. The authors conclude that students are at risk for needlestick injuries; however, underreporting is frequent.

Educational Measurement↗
PubMed1992

Detection of Listeria monocytogenes by non-radioactive RNA probe and polymerase chain reaction.

A HindIII fragment, 651-base-pair, from the listeriolysin 0 gene of Listeria monocytogenes was cloned into pGEM4Z. Radioactive 32P labeled and non-radioactive digoxigenin labeled RNA probes were made by in vitro transcriptions. These probes hybridized only to L. monocytogenes strains. Polymerase chain reaction was performed by using a 22-mer and a 23-mer oligonucleotide primer, and segment of about 700-base-pair was amplified only in L. monocytogenes strains and this band was visualized by hybridization with the non-radioactive probe.

Base Sequence↗