Biomedical subjects

A Ho

Publications and source records attributed to A Ho.

At least 109 records · Page 6Linked to original sources

PubMed1997

Prodynorphin, proenkephalin and kappa opioid receptor mRNA responses to acute "binge" cocaine.

Previous studies showed that preprodynorphin (ppDyn) mRNA increases in caudate-putamen while kappa opioid receptor (KOR) mRNA decreases in substantia nigra after 3 and 14 days "binge" cocaine. To further characterize opioid mRNA responses, rats were administered: saline; 1 day cocaine followed by 1 day saline; 1 day cocaine; or 2 days cocaine. ppDyn mRNA in caudate-putamen increased in both groups receiving cocaine on the final day compared to groups receiving saline. Preproenkephalin (ppEnk) mRNA in caudate-putamen increased, and KOR mRNA in substantia nigra decreased, after 2 days of cocaine. Thus ppDyn mRNA is elevated acutely by cocaine, while ppEnk and KOR mRNAs show a significant response only on the second day of "binge" cocaine.

Animals↗

PubMed1997

Distribution and polysome association of full-length and 3' truncated preproenkephalin mRNA in the guinea-pig brain.

The preproenkephalin gene is expressed in the mammalian central and peripheral nervous system as well as in other tissues, including the pituitary, adrenal medulla, lymphocytes, and reproductive and digestive systems. In the guinea-pig brain, preproenkephalin mRNA transcripts are cleaved at a specific site located in the 3' untranslated region. We used a solution hybridization RNAse protection assay to measure total levels of preproenkephalin mRNA and to determine the ratio of full-length to truncated forms in the pituitary and 12 brain regions of the guinea-pig. The overall distribution of preproenkephalin mRNA was found to be similar to that observed in other species in which it has been measured, with the highest levels of expression located in the caudate putamen and nucleus accumbens. The 3' truncated form was found throughout the brain in varying levels depending on the region. In nine regions examined, levels of the shorter form varied between 35 and 59% of total preproenkephalin mRNA content. The cerebellum and pons/medulla contained 17% each. In the pituitary, the only non-brain tissue studied, the truncated form constituted only 4% of total preproenkephalin mRNA. No correlation between absolute mRNA levels and the distribution between the two forms was observed. Both the full-length and 3' truncated mRNA forms were associated with polysomes isolated from the guinea-pig caudate putamen by sucrose density gradient centrifugation, suggesting that both mRNA forms may be actively translated. The distribution between the two forms, however, was different on the polysomal and dissociated monosomal gradients: the polysomal preproenkephalin mRNA contained a higher proportion of the full-length form whereas the monosomal fractions contained slightly more of the truncated form. This discontinuity in the amount of the two forms between polysomal and non-polysomal mRNA may suggest that the full-length form is more readily incorporated into polysomes.

Animals↗

PubMed1997

Variation in optic zone radii of a contact lens during manufacturing and the effects of temperature on this variation.

There is little information in the literature on the causes of variation in the optic zone radii of a contact lens and the effects of temperature on this variation. In this study, the lathe cutting method of producing contact lenses was reviewed. The cause of the variation in the back optic zone radius was then identified as change in the operating condition from that of the calibrating one. Also, using finite element and theoretical methods, it was found that the effect of an increase in lens blank temperature is to make the back optic zone radius obtained steeper than that required, and this effect was verified experimentally.

Journal Article↗

PubMed1997

Analysis of the colleting method of producing spherical surfaces in contact lens blanks using finite element and experimental methods.

In contact lens manufacturing, the collet chuck is one of the most common methods of holding a lens blank in a lathe in order to cut a back optic zone. In this method the lens blank is compressed by a colleting force, and the effects of this force on the back optic zone radius of the lens blank are not well known. If these effects are known, improved back optic zone radius dimensions may be obtained. In this paper, the finite element and experimental results obtained for the effects of colleting on the back optic zone radius are presented and discussed.

Journal Article↗

PubMed1997

Analysis of the crimping method of producing toric surfaces in contact lens blanks using finite element and experimental methods.

One of the most common methods of producing a toric surface in a contact lens blank is crimping. This method has the advantages of being simple and cheap, but the toric surface dimensions obtained, especially at higher cylinders, can be less accurate. The relationships between the crimping parameters used to produce the toric surface and the dimensions of the toric surface obtained are not well known. If these relationships are known, improved toric surface dimensions may be obtained. In this paper, finite element analysis and experimental results obtained for these relationships are presented and discussed.

Journal Article↗

PubMed1997

Post-transcriptional regulation of the gonadotropin-releasing hormone gene in GT1-7 cells.

GT1-7 cells respond to treatment with the phorbol ester, phorbol 12-myristate 13-acetate (PMA), with an inhibition of transcription of the proGnRH gene and decreases in GnRH mRNA levels. However, the timing of this decrease in GnRH mRNA levels suggests that a decrease in GnRH mRNA stability may be involved in addition to an inhibition of transcription of the proGnRH gene. To address this possibility, we treated GT1-7 cells with 100 nM PMA for 4 h and then monitored GnRH mRNA levels over time after blockade of GnRH gene transcription with DRB. PMA treatment caused GnRH mRNA half-life to decrease from 30 to 11 h. Then, to verify this observation, we examined changes in GnRH mRNA poly (A) tail length, which may be a reflection of mRNA turnover, following treatment of GT1-7 cells with PMA or vehicle for 0, 4, 8 or 24 h. The poly (A) tail was removed from half of the GT1 cytoplasmic RNA sample by digestion with RNase H and the difference in GnRH mRNA size with and without RNase H treatment was determined by Northern hybridization. PMA treatment (4 and 8 h) resulted in a significant decrease in the length of the GnRH mRNA poly (A) tail, consistent with a decrease in GnRH mRNA stability. This finding suggests that GnRH mRNA turnover is inducible by substances such as PMA. Our study indicates that a change in mRNA stability is one of a multiplicity of levels at which GnRH gene expression is regulated.

Blotting, Northern↗

PubMed1997

Meningitis in Hong Kong children, with special reference to the infrequency of haemophilus and meningococcal infection.

OBJECTIVE: To study the epidemiologic and aetiologic features of meningitis in children in Hong Kong. METHODOLOGY: A retrospective study of 85 children resident in the New Territory East region of Hong Kong admitted to a teaching Hospital because of meningitis during a 9 year period. RESULTS: Mycobacterium tuberculosis was the most common aetiological agent accounting for 13 cases (15.3%). Other bacteria accounted for 41 cases (48%); among these one fifth were caused by Haemophilus influenzae type b. The overall admission rates for tuberculous meningitis in Chinese children were 0.76/100,000 (95% CI 0.25-1.78) and 0.42/100,000 (CI 0.19-0.8) per year, respectively, for under 5 year olds and under 15 year olds. The overall annual incidence rates of bacterial meningitis other than tuberculous were 5.2/100,000 (CI 3.72-7.43) and 1.6/100,000 (CI 1.14-2.29) for Chinese children under 5 years and under 15 years, respectively. The annual incidence of H. influenzae meningitis in Chinese children under 5 years old was low at 1.1/100,000 (0.43-2.2). All five cases of meningococcal meningitis were in Vietnamese children (under 5 years of age incidence: 13.0/100,000 per year, CI 4.2-30.3). There were no cases of meningococcal meningitis in Chinese children during the 9 year period. CONCLUSION: M. tuberculosis was the most common aetiological agent of meningitis in Hong Kong children. The incidence of haemophilus or meningococcal meningitis was very low.

Adolescent↗

PubMed1997

Hospitalized patients with community-acquired pneumonia in Hong Kong: a randomized study comparing imipenem/cilastatin and ceftazidime.

The aetiology and outcome of hospitalized patients with moderate to severe community-acquired pneumonia (CAP) were evaluated in 60 adult patients (38 male 22 female, mean age 68.4 years). They were randomized for treatment with either ceftazidime or imipenem/cilastatin intravenously for 7 days. Bacteriological diagnoses were made in 25 cases (41.6%): Streptococcus pneumoniae (5), Haemophilus influenzae (5), Pseudomonas spp. in particular Pseudomonas aeruginosa (8), Staphylococcus aureus (4), Chlamydia spp. (2), Mycobacterium tuberculosis (2) and Moraxella catarrhalis (3); mixed organisms were found in 4 patients. Forty-two patients (70%) responded satisfactorily to the regimens with improvement in sputum purulence cough and dyspnoea scores; there was no difference in response between the two groups. Sixteen patients (26.6%) underwent bronchoscopy on day 4 because of inadequate response to the antibiotics regimens, and 9 of them (15%) required a modification of the initial treatment with addition of erythromycin in 5 patients vancomycin in 1 cloxacillin in 1 and antituberculous drugs in 2. Three out of the 60 patients (5%) died of pulmonary sepsis: the aetiological agents were M. tuberculosis in one, Pseudomonas spp./methicillin-resistant S. aureus in another, but were not identified in the third. We conclude that treatment with either ceftazidime or imipenem/cilastatin was efficacious for moderate to severe CAP in Hong Kong.

Adult↗

PubMed1997

Prevalence of asthma and allergy in Hong Kong schoolchildren: an ISAAC study.

Asthma and allergic disease in children is increasing in many Western countries but such trend has not been well-defined in Chinese populations. This paper aims to determine the prevalence of asthma and allergic disease in Hong Kong schoolchildren and compare it with previous data to identify a changing trend. We studied 4,665 schoolchildren aged 13-14 yrs using the International Study of Asthma and Allergy in Childhood (ISAAC) protocol to determine prevalence rates for asthma, wheeze, respiratory symptoms, rhinitis and eczema in 1994-1995. Additional questions on education levels of the parents and smoking status were also asked. Concordance between responses to the written and video questionnaires was good (76% for wheeze ever, 80% for current wheeze). Prevalence rates for asthma ever, wheeze ever, and current wheeze were 11, 20 and 12%, respectively, and were greater in boys (p < 0.05). Rhinitis affected slightly over half of the subjects (52%), and eczema was reported by a sixth (15%), whilst current rhinitis and current eczema were present in 44% and 3.6% of children, respectively. In multiple logistic regression: odds ratio male sex (OR) 1.47; (95% confidence interval (95% CI) 1.15-1.86); current rhinitis (OR 3.00; 95% CI 2.36-3.81); current eczema (OR 2.34; 95% CI 1.40-3.93); and active smoking (OR 2.00; 95% CI 1.38-2.89) were associated with current wheeze; whilst severe wheezing attack was associated with: current rhinitis (OR 2.72; 95% CI 1.47-5.02); current eczema (OR 6.13; 95% CI 2.82-13.33); and active smoking (OR 4.62; 95% CI 2.43-8.76). Age, parental education and passive smoking were not important factors. When compared to previous epidemiological data obtained in 1992, the prevalence rates for asthma ever and wheeze ever had increased by 71 and 255%, respectively, in Hong Kong schoolchildren. The severity of asthma and respiratory symptoms showed a similar increasing trend. Further studies should aim to identify the role of the environment in the pathogenesis of asthma.

Adolescent↗

PubMed1997

Prevalence of sleep-disordered breathing in diastolic heart failure.

OBJECTIVE: Sleep-disordered breathing (SDB) is common in congestive heart failure. While isolated diastolic heart failure (DHF) accounts for up to a third of all cases of congestive heart failure, the prevalence of SDB in DHF is unknown. We aim to determine the prevalence and characteristics of SDB in a group of patients with symptomatic DHF. METHODS: Twenty subjects with symptomatic DHF (New York Heart Association class II or III) and isolated diastolic dysfunction on echocardiography were assessed with lung function tests, modified sleep and health questionnaire, and overnight polysomnography. Significant SDB was defined as an apnea/hypopnea index (AHI) > 10. RESULTS: Thirteen female and seven male subjects (mean age, 65+/-6.0 years; mean body mass index (BMI), 28+/-3.2) were evaluated, of whom 17 (85%) had a diagnosis of hypertension. Overall sleep quality was poor, with fragmentation and frequent arousals associated with respiratory events. Fifty-five percent of the patients had significant SDB, mainly obstructive apneas. BMI and the prevalence of hypertension were similar in patients with and without SDB. The deceleration time, an index of diastolic dysfunction, was more prolonged in the group with SDB (236+/-40 ms vs 282+/-31 ms; p<0.05). As a group, a lower minimum percentage arterial oxygen saturation during sleep, but not the AHI was associated with more severe degree of diastolic dysfunction on echocardiogram, including a lower ratio between the early peak transmittal flow velocity and the late peak atrial systolic velocity (rho=0.57; p<0.05) and a prolonged isovolumic relaxation time (rho=-0.54; p<0.05). CONCLUSIONS: SDB is common in patients with DHF. Patients with DHF and SDB may be associated with worse diastolic dysfunction than those without SDB, although a causal relationship remains to be established.

Aged↗

PubMed1997

Hereditary angioedema in a Chinese family.

Hereditary angioedema is characterised by recurrent episodes of peri-orbital and peri-oral swelling which can cause an upper airway obstruction, abdominal pain, vomiting, diarrhoea, and even hypotensive collapse. This potentially fatal condition is frequently misdiagnosed; its early recognition and appropriate treatment are thus important. We report a familial cluster of hereditary angioedema in a Chinese family and describe the clinical course of two patients.

Journal Article↗

PubMed1997

Allergic sensitisation to common environmental allergens in adult asthmatics in Hong Kong.

The relationship between immediate skin reactivity to common allergens and adult asthma is not well defined. We retrospectively evaluated the profile of allergen sensitisation to common environmental allergens in 666 adult asthma patients at an asthma clinic in a teaching hospital in Hong Kong. Four hundred and seventy-one asthmatics (70.7%) were atopic; there were more males than females, although the difference did not reach statistical significance. The skin test positively rate decreased significantly with age so that asthmatics aged 35 years and older were four to six times less likely to be atopic and eight to 12 times less likely to be allergic to Dermatophagoides pteronyssinus, compared with young asthmatics aged 15 to 24 years (P<0.001). Inhalant allergy was more common than food allergy and of the inhalants, indoor allergens, including house dust mite and cockcoach were more important than outdoor allergens. The allergens most frequently associated with positive skin tests were D. pteronyssinus (62.2%), D. farinae (60%), cockroach (40.7%), cat dander (24.0%), and royal jelly (16.8%). In conclusion, allergen sensitisation is common in adult asthmatics in Hong Kong, and allergen avoidance should be included as part of the preventive strategies for controlling the disease in the community.

Journal Article↗

PubMed1997

Prevalence of latex allergy in hospital staff in Hong Kong.

BACKGROUND: The prevalence of latex allergy in healthcare workers in Asian populations is unknown. METHODS: We studied 1472 employees in a teaching hospital in Hong Kong using written questionnaires and 133 respondents underwent skin prick testing to latex glove eluates and common allergens. RESULTS: Glove-related symptoms were common and 455 (30.9%) reported one or more symptoms, the majority of which could be classified as glove dermatitis (GD). On the other hand, symptoms suggestive of latex allergy such as urticaria, rhinitis, wheeze and asthma, were encountered less frequently and were noted by 3.3%. In particular, one developed asthma and two had wheezing, but there was no report of anaphylaxis. A total of 9.9% reported allergic symptoms from contact with other latex devices, in particular, rubber bands, rubber boots, goggles and swimming. Nine subjects (6.8%) had positive skin test to one or more of the five latex extracts. All were atopic to common allergens. Skin test positivity to latex and banana extracts was positively correlated (P < 0.05). In univariate logistic regression, daily glove use, personal history of allergic disease and history of allergic symptoms to latex-containing devices other than gloves were significant risk factors for both GD and LA. Nurses were more likely to complain of GD and workers with positive skin test to latex were 8.6 times more likely to have symptoms of LA. In multiple logistic regression, the remaining significant associations were between history of daily glove use and GD (OR = 50.11, 95% CI 15.88-158.13), and between positive latex skin test and LA (OR = 8.14, 95% CI 1.27-52.36). CONCLUSION: Glove-related symptoms are common in healthcare workers in Hong Kong. Gloved healthcare workers are at risk of becoming sensitized to latex, and those with positive latex skin tests, long glove exposure time and frequent glove changes are at risk of clinical latex allergy.

Adult↗

PubMed1997

Royal jelly consumption and hypersensitivity in the community.

BACKGROUND: Royal jelly consumption has recently been linked with acute asthma, anaphylaxis and death. A cross-sectional survey was conducted to determine the prevalence of and the relationship between royal jelly consumption and hypersensitivity reactions. METHODS: 1472 hospital employees of a teaching hospital in Hong Kong completed a questionnaire on royal jelly consumption and related allergic symptoms, and 176 questionnaire respondents and 300 consecutive asthma clinic patients were skin tested to royal jelly. RESULTS: Royal jelly consumption was high, with 461 out of 1472 subjects (31.3%) having taken royal jelly in the past. A total of nine subjects reported 14 adverse reactions to royal jelly, including urticaria, eczema, rhinitis and acute asthma. Thirteen out of 176 questionnaire respondents (7.4%) and 23 out of 300 consecutive asthma clinic attendees (7.3%) had positive skin test to pure royal jelly. All but one of the 36 subjects with positive royal jelly skin test were atopic to other common allergens. Positive associations were found between positive royal jelly skin test and atopy (OR = 33.73, 95% CI 4.51 to 252.11), adverse reactions to royal jelly and a history of clinical allergy (OR = 2.88, 95% CI 0.72 to 11.58), but not between royal jelly symptoms and previous royal jelly intake. CONCLUSION: Royal jelly consumption is high in the community of Hong Kong. Atopic individuals are at high risk of sensitization to royal jelly but the precise relationship between royal jelly use, positive royal jelly skin test and clinical manifestations of adverse reactions to royal jelly, remains to be defined.

Adolescent↗

PubMed1997

Comparison of the ISAAC video questionnaire (AVQ3.0) with the ISAAC written questionnaire for estimating asthma associated with bronchial hyperreactivity.

BACKGROUND: A standardized protocol is essential for international comparisons of asthma prevalence and severity. The International Study of Asthma and Allergies in Childhood (ISAAC) used a standardized written questionnaire (WQ) and a video questionnaire (AVQ3.0) to survey the prevalence and severity of asthma in 13-14-year-old schoolchildren in different countries. OBJECTIVE: To compare the effectiveness of WQ and AVQ3.0 in predicting bronchial hyperresponsiveness (BHR), defined as having a provocation dose of inhaled methacholine causing a 20% fall in baseline FEV1 of 7.8 mumol. METHODS: One hundred and eighty-nine Chinese schoolchildren completed a written questionnaire followed by a video questionnaire on asthma symptoms. They then underwent bronchial challenge to methacholine. RESULTS: Fair correlations were seen between the first two corresponding questions (moderate wheezing at rest and exercise wheeze) in the two questionnaires with Kapper indices of 0.44 and 0.43, respectively. The ability to predict BHR, as indicated by the Youden's index, was similar between the corresponding questions of the two questionnaires, except for 'severe wheeze' which had a significantly higher Youden's index in AVQ3.0 (0.44) than the corresponding question in WQ (0.11, P < 0.05). CONCLUSION: The ISAAC International video questionnaire is at least as effective as the ISAAC written questionnaire in predicting BHR. It therefore provides a simple and valid tool for international comparisons of asthma prevalence and severity.

Adolescent↗

PubMed1997

Clinical evaluation of the effect of a hydrogen peroxide mouth rinse, sodium bicarbonate dentifrice, and mouth moisturizer on oral health.

The objective of this 60-day single-blind, parallel trial, using 150 subjects, was to evaluate the effect of a 20% sodium bicarbonate dentifrice, a 1.5% hydrogen peroxide solution and a mouth moisturizer on oral tissues and microflora. Subjects were randomly assigned to one of five groups. The treatments were: 1) Sage dentifrice (sodium bicarbonate). Toothette Plus containing baking soda saturated with the hydrogen peroxide solution and use of a mouth moisturizer, 2) Crest dentifrice, Toothette Plus containing baking soda saturated with the hydrogen peroxide solution and use of a mouth moisturizer, 3) Crest dentifrice, Toothette Plus containing baking soda with a control solution and no mouth moisturizer, 4) Crest dentifrice, Toothette (without baking soda), saturated with a control solution and no mouth moisturizer, and 5) Crest dentifrice, Toothette saturated with 1.5% flavored H2O2 and no mouth moisturizer. From a subgroup of 35 patients (seven from each group) buccal smears for exfoliative cytology were taken as were supragingival microbiological samples from the mesial aspect of first molars (pooled). Buccal smears were evaluated for signs of histopathological changes. Microbiological samples from supra- and subgingival plaque for P. gingivalis, P. intermedia, A. actinomycetemcomitans. A viscosus, F. nucleatum, F. sanguis and C. albicans were evaluated. Clinical parameters measured were a stain index (SI), the modified gingival index (MGI), and a plaque index (PI). There were no adverse changes in the oral microflora and no anaplastic or other pathological changes in any subjects. Clinical parameters showed a statistically significant reduction in the MGI ranging from 26.7-29.9% with no significant differences among the groups (p > 0.05). The PI showed small reductions in all groups except group 2, but the differences were not statistically significant from each other or baseline (p > 0.05). The SI revealed slight increases in all groups and no differences among the groups. It can be concluded that use of Sage dentifrice, Toothette Plus saturated with Perox-A-Mint and Sage Mouth Moisturizer are safe to oral tissues. Using these components did not result in clinically noticeable stain formation, promote plaque formation, or produce any significant adverse changes in the oral microflora.

Adolescent↗

PubMed1997

Effects of subgingival chlorhexidine irrigation on peri-implant maintenance.

PURPOSE: To evaluate the effect of irrigation with 0.06% chlorhexidine (PerioGard) (CHX) using a powered oral irrigator (Water Pik) with a special subgingival irrigating tip (Pik Pocket Subgingival Tip) compared to rinsing with 0.12% chlorhexidine gluconate once daily. MATERIALS AND METHODS: Following a prophylaxis, patients were randomly assigned to an irrigation or a rinse group. The following clinical parameters were measured at baseline and at the 3-month end of the study: Modified Gingival Index (MGI), Plaque Index (PI), Bleeding Index (BI), and Calculus Index (CI). Also, a Stain Index (SI) was measured at 3 months. RESULTS: Patients irrigating with diluted CHX showed a statistically significant reduction (P < 0.05) from their baseline in the MGI, PI, BI, and CI scores at 3 months. In the rinse group both MGI and BI showed statistically significant reduction from their baseline (P < 0.05) at 3 months. The rinse group showed a nonsignificant (P > 0.05) increase from baseline in CI and a nonsignificant decrease in PI. Intergroup comparisons showed that CHX irrigation produced statistically significantly greater reductions than CHX rinsing in the PI, MGI, and SI. The irrigation group also showed a greater reduction in BI and CI than the rinsing group but these differences were not statistically significant (P = 0.12). The results of this study suggest that use of diluted 0.06% CHX when used in a powered irrigator may be a valuable adjunct to oral health in patients with implants.

Adult↗

PubMed1996

Steady-state methadone in rats does not change mRNA levels of corticotropin-releasing factor, its pituitary receptor or proopiomelanocortin.

Male Fischer rats received either methadone (a long-acting opioid agonist, 10 mg/kg/day) or saline (24 microliters/day) subcutaneously by osmotic minipumps for 7 days. Chronic steady-state methadone administration did not alter (a) corticotropin-releasing factor (CRF) mRNA in the hypothalamus, (b) proopiomelanocortin (POMC) and CRF type 1 receptor (CRF-R1) mRNAs in the anterior lobe and neurointermediate/posterior lobe of the pituitary, or (c) circulating levels of corticosterone. No change was found in levels of either POMC mRNA in the hypothalamus and amygdala, or CRF mRNA in the frontal cortex, olfactory bulb and amygdala. These results demonstrate that neither the activity of the hypothalamic-pituitary-adrenal axis, nor the beta-endorphin and CRF systems in the brain, are altered by steady-state occupancy of opioid receptors with the long-acting opioid agonist methadone.

Animals↗