PubMed Health⌕ Search

Biomedical subjects

A M Chang

Publications and source records attributed to A M Chang.

At least 19 recordsLinked to original sources
PubMed1992

Relationship of cytochrome P450 activity to Clara cell cytotoxicity. II. Comparison of stereoselectivity of naphthalene epoxidation in lung and nasal mucosa of mouse, hamster, rat and rhesus monkey.

Naphthalene, a murine Clara cell cytotoxicant, is metabolized by cytochrome P450 monooxygenases to unstable, chiral epoxide metabolites which can conjugate with glutathione in the presence of glutathione transferases. Analysis of the three diasteriomeric glutathione adducts produced from conjugation of naphthalene oxides was used in these studies to characterize the stereochemistry of naphthalene epoxidation in preparations of nasal mucosa, lung and liver of the mouse, rat, hamster and monkey. The highest rates of naphthalene metabolism were observed in mouse lung and liver microsomal incubations. Rat, hamster and monkey lung microsomal preparations metabolized naphthalene at 12, 37, and 1%, respectively, of the rate observed in mouse lung. The ratio of chiral epoxides produced in microsomal incubations was dependent upon the concentration of naphthalene. At high substrate concentrations (0.25-1.0 mM), the ratio of 1R,2S- to 1S,2R-naphthalene oxide, as assessed by the glutathione adducts generated (adduct 2/adducts 1 + 3), in murine lung microsomal incubations was 10:1 and at low concentrations (0.062 mM and below) varied from 13.8:1 to 30:1. In contrast, the ratio of 1R,2S- to 1S,2R-naphthalene oxide produced in murine liver microsomes varied from 1:1 at high substrate concentrations to 5:1 at low substrate concentrations. The ratio of naphthalene oxides was unaffected by the concentration of glutathione in the incubation. In contrast to the preferential formation of 1R,2S-naphthalene oxide observed in mouse lung microsomal preparations, lung microsomes derived from the rat, hamster and monkey yielded 1R,2S- to 1S,2R-epoxide ratios of 0.48, 0.61 and 0.12, respectively, at 0.5 mM naphthalene.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Nurses' perceptions of their problem-solving ability.

A problem-solving approach to nursing practice has been advocated in the nursing literature for some time. However, the extent to which nurses perceive themselves as capable problem solvers or improve their problem-solving ability during their nursing education is not generally known. The purpose of this study was to determine the relationship between nurses' perceptions of their problem-solving ability and their course of study. The Problem-Solving Inventory (PSI) was developed by Heppner and colleagues (1982) to assess attitudes towards and perceptions of problem-solving behaviour. The instrument provides a global appraisal of oneself as a problem solver and assesses perceptions of problem-solving ability. In this study, data were collected from 67 pre and post-registration nursing students in two phases; during their course and on completion of their course. Data from each phase were compared to identify changes in perception of problem-solving behaviour over time. While there was no overall improvement in perceptions of problem-solving ability by phase 2, confidence in problem solving had improved significantly (P less than 0.01). There were improvements according to age, experience, and course being undertaken for the likelihood of approaching rather than avoiding problems, and having personal control over problem solving.

Adult↗
PubMed1991

Clinical algorithms.

Clinical flow charts or algorithms are becoming an increasingly popular means of summarizing the management of a given clinical situation. However they vary greatly in complexity between authors, making comparisons difficult, and detracting from their overall usefulness to medical personnel. We have therefore reviewed the strengths and weaknesses of many published algorithms. As a result of both this and our own experience with clinical algorithms we have identified seven essential elements of clinical management. We believe that acceptance of these elements would improve the efficiency of clinical algorithms, both as a teaching format and as an aid to clinical management.

Algorithms↗
PubMed1990

Salivary oestradiol and progesterone after in vitro fertilization and embryo transfer using different luteal support regimens.

Salivary oestradiol (E2) and progesterone (P) levels have been shown to reflect the biologically active fractions in the serum. The luteal-phase status of stimulated cycles was investigated after in vitro fertilization and embryo transfer (IVF-ET). Thirty patients were randomly allocated to one of three luteal therapy groups: group A had no support, group B had intramuscular P and group C had intramuscular P and human chorionic gonadotrophin (hCG). One pregnancy was achieved in group A, two in group B and three in group C. Significant correlations between salivary and serum levels of E2 and of P in matched samples during luteal phase were found. Salivary E2 levels from luteal day 8 through day 14 and P levels from day 3 through day 14 were significantly higher in the pregnant than in the nonpregnant cycles. Among the nonpregnant cycles, salivary E2 and P levels were significantly higher in group C than in group A or B. These findings suggest that, in stimulated cycles for IVF-ET, determination of salivary E2 and P levels may be used as reliable alternatives to serum concentrations for assessing the luteal phase. Also, the additional hCG has an enhanced luteotrophic effect, as reflected by the higher salivary E2 and P levels, which may lead to a better pregnancy rate.

Chorionic Gonadotropin↗
PubMed1990

The application of basic science concepts to clinical problem-solving.

This study looks at the relationship between anatomical concepts held by medical students and their clinical application, and develops a testable model of how students use basic science concepts for clinical problem-solving. According to the model, the essential prerequisites to solve a clinical problem using basic science information include the appropriate basic science knowledge, the ability to collect and interpret clinical information, with the key concept being the link that must then be made between clinical data and basic science. A detailed analysis of the individual components of the model should help to clarify and resolve some of the debate about the nature and balance of basic science and clinical education. A neurological diagnostic problem was used to test the assumptions of the model in a group of medical students who had minimal clinical experiences. There was no demonstrable relationship between anatomical knowledge as assessed by conventional tests and the diagnosis. There was a powerful relationship between measures of organization of knowledge and diagnosis, suggesting that the organization and development of concepts is the key to correct diagnosis. The findings have significant implications for assessment purposes and suggest that standard methods as generally practised may not measure the appropriate conceptual development and are not congruent with curricular objectives. Through the examination of its different learning outcome measures, the model may also be used to provide a profile of individual students or classes, which should help teachers and students deal with difficulties that may be experienced in learning to link clinical and basic science concepts.

Clinical Competence↗
PubMed1990

Birth-weight of newborns to Chinese women subsequent to a previous abortion.

The mean birth-weight of firstborns of women was significantly higher when there was a previous abortion. The increase was 73.5 and 119.4 g in newborns of women with an induced and a spontaneous abortion respectively. This trend of significant increased birth-weight among firstborns of women with either a previous induced or spontaneous abortion continued for male infants, in recent migrants, and in subjects aged 20-24 and 30-34 years. Stepwise logistic regression analyses showed that a history of an induced or a spontaneous abortion increased the birth-weight of the firstborns, while short maternal stature and female newborn were associated with decreased birth-weight. For low birth-weight, a previous abortion was not selected into the regression models but short maternal stature and female newborns continue to contribute to low birth-weight. Prematurity and mean gestation were found not to be associated with previous abortion using logistic regression analyses.

Abortion, Induced↗
PubMed1989

Effect of folate supplement on pregnant women with beta-thalassaemia minor.

The effect of folate supplement on the haemoglobin concentration and outcome of pregnancy was studied in a group of Chinese women with uncomplicated beta-thalassaemia minor who delivered in our hospital between 1984-1987. The patients who received 5 mg folate daily showed a significant increase in the predelivery haemoglobin concentration, which was significantly higher than that in patients who received 0.25 mg daily. When the effect of parity was analysed we found that: multiparas were significantly older, had lower haemoglobin before delivery, and more of them required transfusion. Folate 5 mg daily significantly increased the predelivery haemoglobin concentration in both nulliparas and multiparas. It is concluded that folate 5 mg daily improves the haemoglobin concentration in pregnant women with beta-thalassaemia minor and that this should be prescribed.

Adult↗
PubMed1989

Prevalence of cytomegalovirus cervical excretion in pregnant women in Hong Kong.

In 1986 a study was made on the prevalence of cervical colonization by cytomegalovirus (CMV) in normal third trimester pregnant Chinese women in Hong Kong. Seven out of 95 unselected subjects had positive CMV culture, making a prevalence of 7.4%. This is a low prevalence when compared with the prevalence found in other people of Asian origin and similar to the prevalence found in the Caucasians.

Cervix Uteri↗
PubMed1989

Single dose prophylactic antibiotics in caesarean sections.

A prospective, double-blind randomized trial was carried out at the Department of Obstetrics and Gynaecology, the Chinese University of Hong Kong, involving 4 groups of patients receiving a single intravenous dose of placebo, ampicillin, ampicillin and metronidazole, and ampicillin and sulbactam before operation. No difference in postoperative morbidity was present between the 4 groups of patients.

Adult↗
PubMed1988

A controlled trial on wound drainage in caesarean section.

A randomized controlled trial was carried out to investigate the influence of drainage on wound infection following Caesarean section. The incidence of clinical wound infection was significantly reduced if a Redivac suction drain was placed beneath the rectus sheath. Subcutaneous corrugated drains were found to offer no advantage. Three different degrees of postoperative pyrexia are examined for their predictive value for the development of wound sepsis. The influence of duration of amnion rupture and the number of vaginal examinations in labour on the postoperative incidence of wound infection and pyrexia are examined.

Cesarean Section↗
PubMed1987

The outcome of hyperemetic pregnancies complicated by transient hyperthyroidism.

Thirty-nine patients presenting with hyperemesis gravidarum were studied and the subsequent course and outcome of pregnancy between patients with normal and abnormal thyroid function was compared. Seventeen patients (43.6%) developed transient hyperthyroidism, for which a short course of antithyroid treatment was required in 2 patients. There was no difference in the outcome of pregnancy between patients with normal and abnormal thyroid function. The results suggest that while antithyroid treatment is effective for symptomatic control, it is unnecessary in the majority of patients since the condition is self-limiting, and the outcome of pregnancy not adversely affected by the transient hyperthyroidism in hyperemetic patients.

Adult↗
PubMed1987

Determinants of birth-weight in the new territories of Hong Kong.

Weights of babies born in the Prince of Wales Hospital, Hong Kong, in its first 2 years of operation were studied, and compared with previous reports. Birth-weight in Hong Kong appears to have increased significantly in recent years. The method of data collection effects reference standards of birth-weight. The effect of different methods of data collection and statistical treatment of data for providing reference standards of birth-weight are discussed. In this series average birth-weight increased by 6.8 g per year of maternal age, 13.3 g per cm of maternal height, 42.5 g per previous baby and 104.9 g per week of gestational age; males were 110 g heavier than females. The effects of parity became significant at 35 weeks, and that of maternal age and height at 36 weeks; the effect of fetal sex was significant from 38 weeks onwards.

Birth Weight↗
PubMed1987

Mechanism of the therapeutic effect of anisodamine in disseminated intravascular coagulation: study of platelet adhesion and aggregation, malondialdehyde, thromboxane B2, 6-keto-prostaglandin F1 alpha, and microcirculation.

Acute disseminated intravascular coagulation (DIC) is a life-threatening condition that may be encountered in many situations, especially in cases of shock with uncontrollable hemorrhage. Anisodamine, an alkaloid extracted from a Chinese herb, is well known for its dramatic therapeutic effect on DIC. Sixty male rabbits were used to establish an acute DIC model. A total of 240 blood samples were taken for laboratory assays of changes in blood coagulation factors, platelet count, platelet adhesion, platelet aggregation, malondialdehyde (MDA), thromboxane B2 (TXB2), and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). Changes of the microcirculatory status and the rate of the blood flow in the conjunctival capillaries of 60 rabbits were observed with WXS-II microcirculation microscope. Pathological sections of the lungs and kidneys were studied. Our investigation showed the presence of microthrombi in the microvasculature. After treatment with anisodamine, the prothrombin time stayed in the normal range, fibrinogen consumption was lessened, adenosine-diphosphate-induced platelet aggregation was inhibited, thromboxane B2 and malondialdehyde concentrations were significantly lower than in the control group, and the elevated quantity of 6-keto-PGF1 alpha was spared. We concluded that the anti-platelet-aggregating, microcirculation-facilitating, thromboxane-B2-inhibiting, malondialdehyde-inhibiting, and 6-keto-PGF1 alpha-sparing effects of anisodamine are the important mechanisms of its dramatic therapeutic effect on DIC.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Peptide YY release by fatty acids is sufficient to inhibit gastric emptying in dogs.

Peptide YY is a candidate enterogastrone localized to endocrine cells of the ileocolonic mucosa. The purpose of the present study was to determine if blood levels of peptide YY observed after perfusion of the intestine with fatty acids are capable of slowing gastric emptying. Gastric emptying of a 300-ml saline meal was monitored during intravenous infusion of normal saline or graded doses of peptide YY. Gastric emptying was significantly inhibited by infusion of peptide YY in doses of 200 and 400 pmol/kg X h. During the saline control study, 229 +/- 12 ml of the 300-ml saline meal emptied by 10 min. This figure was reduced (p less than 0.01) to 110 +/- 28 ml by the infusion of peptide YY at a dose of 200 pmol/kg X h. This dose of peptide YY produced plasma concentrations (delta PYY = 239 +/- 50 pM) that were lower than those seen in response to intestinal perfusion of oleic acid (delta PYY = 395 +/- 55 pM) in the same animals. We conclude that perfusion of the intestine with oleic acid releases peptide YY in amounts sufficient to slow gastric emptying.

Animals↗