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Biomedical subjects

K C Tang

Publications and source records attributed to K C Tang.

30 records · Page 2Linked to original sources
PubMed1995

Critical factors in the determination of focus group size.

From a theoretical perspective, it is difficult to decide an optimal number of participants that should be included in a focus group. Despite recent attempts, critical factors for the determination of the size of a focus group remain uncertain and can further be elaborated. From a practical perspective, this paper proposes four other factors that can be used for the determination of focus group size. These are: the number of questions asked, the allotted time for each question, the format of the focus group session and the duration of the session. Above all, the size of a group should first be determined by the aims of the research study.

Focus Groups↗
PubMed1995

Scanning laser ophthalmoscopy of choroidal neovascularisation using indocyanine green.

BACKGROUND: Choroidal neovascularisation is an important cause of visual loss in age-related macular degeneration. Visualisation of these choroidal abnormalities with fluorescein angiography may be difficult, particularly if there is haemorrhage, excessive pigment, or excessive fluorescence. We report on our experience with indocyanine green (ICG) angiography in demonstrating choroidal neovascularisation. METHOD: Patients with suspected choroidal neovascularisation were assessed with indocyanine green angiography using the Rodenstock Scanning Laser Ophthalmoscope and results recorded on a videotape. Fluorescein angiograms were also obtained in a similar fashion. The angiograms were then compared. RESULTS: In some instances ICG angiography was able to demonstrate the margins and structure of choroidal neovascular membranes more clearly than fluorescein, particularly in the presence of haemorrphage, excessive fluorescence and blocked fluorescence. However, there were instances where it was difficult to interpret the choroidal abnormalities found. Some illustrative cases are discussed. CONCLUSION: We conclude that ICG angiography is a useful adjunct to fluorescein angiography in detection and delineation of choroidal neovascularisation, but that further study is needed.

Aged↗
PubMed1995

A review of 5 existing guidelines for planning focus groups in GP research.

The use of a focus group as a research method has become increasingly common in general practice related studies. Although existing guidelines for planning focus groups are very useful, a review of these guidelines indicate that a few of them are vague and need further elaboration. The authors review five existing guidelines for planning focus groups. These are size, number, duration, format and composition of a focus group. Suggestions have been made to address the uncertainties in these areas when a focus group is used. This paper was a section of manuscript presented at the 2nd International Qualitative Health Research Conference on 11 June 1994, Hershey, Pennsylvania.

Family Practice↗
PubMed1994

Qigong therapy--its effectiveness and regulation.

Qigong has become increasingly popular as a modality in traditional Chinese medical care. It may be effective in treating diseases. However, it is not uncommon to hear complaints about the ineffectiveness of such treatment. This paper attempts to look at the recent promotion of Qigong as an effective form of health care and the regulation of Qigong practitioners in China by a review of literature and interviews with key informants. Although it is premature to conclude that Qigong is another therapeutic modality in traditional Chinese medicine, it is also premature to rule out the possible therapeutic efficacy of Qigong, in particular, internal Qi. Even if medical Qigong is effective, the establishment and enforcement of standards of practice and codes of ethics amongst Qigong masters will remain unresolved as there has not yet been any effective way to assess the competence of a Qigong master. Although a number of control measures have been proposed in this paper, a better understanding of the educational, professional and ethical standards and efficacy of such a practice is required.

Breathing Exercises↗
PubMed1993

Stimulatory effects of bombesin-like peptides on suprachiasmatic neurons in brain slices.

The effects of bombesin on hypothalamic suprachiasmatic (SCN) neurons were tested in this study using extracellular single-unit recording in brain tissue slices. Fresh slices containing the SCN were obtained from adult ovariectomized Sprague-Dawley rats. Bombesin in pmol ranges stimulated 75% of irregular firing SCN neurons (n = 113), while it stimulated and inhibited 17% and 34% of regular firing units, respectively. Half of the regular firing SCN units, however, were not responsive to bombesin (49% of 61 units). A dose-dependent (from 5 to 500 pmol) excitatory effect of bombesin on SCN neurons was also observed. Pretreatment with [Leu13-psi(CH2NH)-Leu14]-bombesin, a bombesin receptor antagonist, blocked the action of bombesin in 67% of 18 units responded to bombesin, indicating a specific receptor is involved in the action. Gastrin-releasing peptide, a well-recognized bombesin-like peptide in mammals, behaved almost the same as bombesin did in most SCN neurons tested (same responses in 24 of 25 units). The present finding indicates that bomesin-like peptides may play a significant role in the SCN for the rhythmic control mechanism.

Animals↗
PubMed1992

Low calcium/high magnesium medium increases activities of hypothalamic arcuate and suprachiasmatic neurons in brain tissue slices.

Extracellular single-unit recording was conducted in hypothalamic arcuate (ARC) and suprachiasmatic nucleus (SCN) in rat brain slices. The perifusion medium was switched from normal artificial cerebrospinal fluid (ACSF) to ACSF containing low Ca2+ and high Mg2+ to test the effect of extracellular calcium on the spontaneous activities of these neurons and their responses to some test agents. It was found that almost all of the ARC and SCN units tested increased their firing rates in low Ca2+, high Mg2+ ACSF, and exhibited more significant responses to excitatory test agents. The effects of low Ca2+, high Mg2+ ACSF were repeatable and reversible. The results suggest that extracellular Ca2+ is essential in maintaining the membrane stability of most hypothalamic neurons and most agents tested are acting postsynaptically on the unit recorded.

Action Potentials↗
PubMed1991

Effects of heterologous growth hormones on hypothalamic and pituitary function in transgenic mice.

The expression of the mouse metallothionein-I (mMT) promoter/human growth hormone (hGH) fusion gene in transgenic mice leads to female sterility and major alterations in the function of the hypothalamic-adenohypophyseal system. These alterations include increases in median-eminence norepinephrine turnover and plasma LH levels, and a decrease in plasma prolactin levels in intact males, and an increase in median-eminence dopamine turnover combined with the suppression of plasma prolactin levels in ovariectomized females. To further characterize these changes and to determine whether they are due to the lactogenic or somatotropic activity of hGH, we have studied hypothalamic and pituitary function in transgenic mice expressing mMT/hGH, mMT/hGH.B 'variant', or mMT/bGH fusion genes. In males, the expression of the hGH.B gene was associated with a reduction in pituitary prolactin release in vitro and an increase in LH response to LHRH stimulation, while the bGH transgene did not affect any of the examined parameters of LH and prolactin release. Median-eminence norepinephrine turnover was increased in each of the three lines of transgenic males, while median-eminence dopamine turnover was reduced only in animals expressing the hGH.B gene. In ovariectomized females, plasma LH was suppressed by hGH variant expression, while median-eminence norepinephrine turnover was suppressed in both hGH.B and bGH animals. The turnover of dopamine was increased in the median eminence of females expressing either of the human genes (hGH or gHG.B) and reduced in the median eminence of ovariectomized bGH females. We conclude that the hGH.B gene is weakly lactogenic in mice, and that the chronic stimulation of either GH receptors (by bGH) or both GH and prolactin receptors (by hGH or hGH.B) can lead to profound alterations in the metabolism of hypothalamic neurotransmitters and pituitary hormone release.

Animals↗
PubMed1986

Single dose ofloxacin in treatment of uncomplicated gonorrhoea.

78 patients (66 male and 12 female) suffering from uncomplicated gonorrhoea were randomly selected to receive a single oral dose of either 400 mg or 600 mg ofloxacin. Of the 59 patients completely followed up penicillinase-producing Neisseria gonorrhoeae strains were cultured in 15 (25.4%) and the overall cure rate was 100%. Both groups showed excellent clinical effectiveness in over 80% and adverse reactions were uncommon and transient. We conclude that a single oral dose of ofloxacin in the studied dosage regimens was highly effective and safe in the treatment of uncomplicated gonorrhoea.

Adult↗
PubMed1982

Effects of S-adenosyl-1,8-diamino-3-thiooctane on polyamine metabolism.

Exposure of mammalian cells (transformed mouse fibroblasts or rat hepatoma cells) to S-adenosyl-1,8-diamino-3-thiooctane produced profound changes in the intracellular polyamine content. Putrescine was increased and spermidine was decreased, consistent with the inhibition of spermidine synthase by this compound, which is a potent and specific "transition-state analogue inhibitor" of the isolated enzyme in vitro. The spermine content of the cells was increased by exposure to this drug presumably since spermine synthase was able to use a greater proportion of the available decarboxylated S-adenosylmethionine when spermidine synthase was inhibited. The decarboxylated S-adenosylmethionine content rose substantially because the activity of S-adenosylmethionine decarboxylase was increased in response to the decline in spermidine. These results indicate that S-adenosyl-1,8-diamino-3-thiooctane is taken up by mammalian cells and is an effective inhibitor of spermidine synthase in vivo and that S-adenosylmethionine decarboxylase is regulated by the content of spermidine, but not of spermine. The growth of SV-3T3 cells was substantially reduced in the presence of S-adenosyl-1,8-diamino-3-thiooctane at concentrations of 50 microM or greater. Such inhibition was reversed by the addition of spermidine but not by putrescine. When SV-3T3 cells were exposed to 5 mM alpha-(difluoromethyl)ornithine and 50 microM S-adenosyl-1,8-diamino-3-thiooctane, the content of all polyamines was reduced. Putrescine and spermidine declined by more than 90% and spermine by 80%. Such cells grew very slowly unless spermidine was added.

Adenosine↗
PubMed1981

Synthesis and evaluation of some stable multisubstrate adducts as specific inhibitors of spermidine synthase.

A new series of aminopropyltransferase inhibitors has been designed in which the nuclephilic aminopropyl acceptor is attached to the aminopropyl donor, S-adenosyl-1-(methylthio)-3-propylamine (decarboxylated S-adenosylmethionine), to form a "multisubstrate adduct". In the present case, S-adenosyl-1,8-diamino-3-thiooctane (2b) and the corresponding methysulfonium salt (3b) have been synthesized. Several compounds of this type were assayed as inhibitors of spermidine synthase, and both 2b and 3b were found to be potent inhibitors of the enzyme. The thioether 2b is the most potent inhibitor of spermidine synthase described to date and is almost totally devoid of inhibitory activity against the closely related aminopropyltransferase, spermine synthase. This type of compound should have use as a specific inhibitor of spermidine biosynthesis in vivo.

Chemical Phenomena↗
PubMedDate not supplied

Predictors of intention to study nursing among school students speaking a language other than English at home.

There is currently a shortage of bilingual nurses in New South Wales. It is important to include bilingual nurses in the workforce to meet not only the cultural and social needs of people speaking a language other than English at home, but also to facilitate the achievement of appropriate health outcomes for a multicultural population. The purpose of this study was to identify demographic and social factors which explain students' intention to study nursing. Respondents were 789 year 11 or 12 students speaking Arabic, Serbo-Croatian, Spanish, Turkish or Vietnamese from twenty-five schools in South Eastern, South Western and Western Sydney. Data were collected through a self-completed questionnaire. Chi square, t-test and logistic regression analysis were used for data analysis. Logistic regression analysis concluded that perceived parental income, years of settlement in Australia and father's occupation were significant factors. Bivariate analysis also revealed that significant differences were found in the intention to study nursing between male and female students and between students with a higher and lower Tertiary Entrance Rank (TER). Parental influence also affects students' intention. However, gender and TER were found to be insignificant after adjustment for other variables in the logistic regression model.

Adolescent↗