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Biomedical subjects

D Cheung

Publications and source records attributed to D Cheung.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of theophylline on tolerance to the bronchoprotective actions of salmeterol in asthmatics in vivo.

Long-term treatment with salmeterol produces tolerance for its protective effects against bronchoconstrictor stimuli in patients with asthma. There is human in vitro evidence that theophylline may prevent beta2-adrenoceptor downregulation. Therefore, we investigated the effect of theophylline on the tolerance to the protective effect of salmeterol against histamine challenge in asthma in vivo. In a parallel 6-wk study, 25 asthmatics were treated with theophylline (mean serum level +/- SEM: 9.9 +/- 1.1 mg/L, Days 1 to 40) or placebo, combined with inhaled salmeterol (50 microgram twice daily, Days 8 to 36). Histamine challenges were carried out by tidal breathing method at entry, and at Days 4, 8, 22, 36, and 40. The response was measured by PC20. There was no significant change in PC20 after 4 d monotherapy with theophylline or placebo (mean difference +/- SEM: 0.54 +/- 0.39 and -0.02 +/- 0.41 doubling dose [DD], respectively; p > 0.15). One hour after the first dose, salmeterol afforded significant protection against histamine, as shown by an increase in PC20 in both the theophylline and placebo group (by 3.49 +/- 0.28 and 3.36 +/- 0.32 DD, respectively; p < 0. 001). However, after 2 and 4 wk salmeterol treatment, the improvements in PC20 by salmeterol were significantly reduced to 1. 80 +/- 0.35 and 1.69 +/- 0.36 DD, respectively, in the theophylline group (p < 0.001), and to 1.55 +/- 0.47 and 1.52 +/- 0.56 DD, respectively, in the placebo group (p < 0.002). These changes were not significantly different between the groups (p > 0.80). After cessation of salmeterol treatment, PC20 was not significantly different from the values at entry in either group (p > 0.90). We conclude that regular theophylline treatment neither prevents, nor worsens, the development of tolerance to the bronchoprotective effect of salmeterol in asthmatics in vivo.

Administration, Inhalation↗
PubMed1998

Risk factors for development of acute renal failure (ARF) requiring dialysis in patients undergoing cardiac surgery.

Acute renal failure (ARF) is one of the major complications after cardiopulmonary bypass for open heart operations. The present study was undertaken to identify the risk factors for the development of ARF following cardiopulmonary bypass (CPB). Four hundred and forty-seven consecutive patients who underwent open heart procedures from July 1994 to June 1995 were analyzed retrospectively. Their mean age was 55.6 +/- 14.2 (SD) years (range, 18 to 80). Dialysis was instituted whenever a patient exhibited inadequate urine output (<0.5 mL/kg/hr) for 2 to 3 hours despite correction of hemodynamic status and diuretic therapy, especially if fluid overload, hyperkalemia, or metabolic acidosis were also present. Twenty variables were analyzed by univariate analysis; these included nine preoperative variables--age, sex, hypertension, atherosclerosis, diabetes mellitus, left ventricular end-diastolic dimension (LVEDD) >5 cm, preoperative congestive heart failure, renal insufficiency (serum creatinine > or =130 micromol/L on two occasions), and sepsis--10 intraoperative variables--duration of CPB, redo procedures, emergency surgery, use of intraaortic balloon pump (IABP) in operating room, use of gentamicin, use of ceftriaxone, use of sulbactam/ampicillin, requirement of deep hypothermic circulatory arrest, duration of low mean perfusion pressure (mean pressure <50 mmHg for more than 30 minutes), operation on multiple valves--and one postoperative variable--significant hypotension (systolic blood pressure less than 90 mmHg for more than 1 hour). Significant variables or the variables having a trend (p<0.1) to be associated with ARF were included in stepwise multiple logistic regression analyses. Three regression analyses were performed separately. The incidence of ARF requiring dialysis in the study period was 15.0%. Significant risk factors for whole group of patients (regression I) were preoperative renal insufficiency (p<0.0001), postoperative hypotension (p<0.0001), cardiopulmonary bypass time more than 140 min (p<0.005), preoperative congestive heart failure (p<0.01), and history of diabetes mellitus (p<0.01). The risk factors in the valve group of patients (regression II) were preoperative renal insufficiency (p<0.0001) and postoperative hypotension (p<0.05). Risk factors in the CABG patients (regression III) were postoperative hypotension (p=0.0001), CPB time more than 140 min (p<0.05), preoperative renal insufficiency (p<0.05), and age (p<0.05). The authors conclude that preoperative renal insufficiency and postoperative hypotension are the most important independent risk factors for ARF in postcardiac surgical patients. In addition, CPB time greater than 140 minutes and old age are also independent risk factors for ARF in CABG patients. CPB time more than 140 minutes, history of diabetes mellitus, and preoperative congestive heart failure are independent risk factors for development of ARF in our total group of patients. These findings may have important clinical implications in the prevention of ARF in postcardiac surgical patients.

Acute Kidney Injury↗
PubMed1997

Protective effect of inhaled budesonide against unlimited airway narrowing to methacholine in atopic patients with asthma.

BACKGROUND: Patients with asthma who have moderate to severe airway hyperresponsiveness often demonstrate progressive, unlimited airway narrowing in response to inhaled bronchoconstrictor stimuli, which is likely to be due to inflammatory changes within the airway wall. It is unknown whether regular therapy with inhaled steroids can limit this excessive response. OBJECTIVE: We investigated the effect of inhaled budesonide on the development of a plateau on the dose-response curve to methacholine in patients with asthma who did not show such a plateau before the study. METHODS: Thirty-one atopic patients with asthma (age, 19 to 31 years; FEV1 > 70% of predicted value; PC20 < 8 mg/ml) with documented absence of a maximal-response plateau to methacholine on two occasions during the run-in period, participated in a double-blind, placebo-controlled, parallel study. Standardized methacholine challenges were performed at -1, 0, 4, 8, and 12 weeks of treatment with inhaled budesonide, 800 microg two times a day, or corresponding placebo, and after a 2-week washout period. Airway response was measured by FEV1 (percent fall from baseline). A maximal-response plateau was considered if three or more consecutive data points fell within a 5% response range. RESULTS: Thirty patients completed the study. There was a steady increase in the number of budesonide-treated patients exhibiting a maximal-response plateau on the dose-response curve from zero of 15 patients at run-in to nine of 14 patients at week 12, as compared with four of 16 patients in the placebo group (p = 0.03, chi square test). This was accompanied by a significant improvement in PC20 in the budesonide group as compared with the placebo group (p < 0.01 at week 12), whereas the changes in FEV1 were not significantly different between the groups (p = 0.77 at week 12). CONCLUSION: Regular treatment with the inhaled corticosteroid budesonide limits maximal airway narrowing in response to methacholine by introducing a plateau on the dose-response curve in patients with asthma, who were initially characterized by the absence of a plateau. This indicates that inhaled steroids are likely to reduce the hazard of unlimited airway narrowing in asthma.

Adult↗
PubMed1997

Relationship between loss in parenchymal elastic recoil pressure and maximal airway narrowing in subjects with alpha1-antitrypsin deficiency.

Airway hyperresponsiveness is characterized by an increase in sensitivity and excessive airway narrowing to inhaled bronchoconstrictor stimuli. There is experimental evidence that maximal airway narrowing is related to lung elasticity in normal and asthmatic subjects. We hypothesized that reduced lung elasticity by parenchymal destruction increases the level of maximal airway narrowing in subjects with alpha1-antitrypsin deficiency. To that end, we measured complete dose-response curves to methacholine, quasistatic pressure-volume (P-V) curves, diffusion capacity for carbon monoxide per unit lung volume (DLCO/VA), and mean lung density by spirometrically controlled computed tomography (CT) scan in eight non- or ex-smoking subjects with alpha1-antitrypsin deficiency. Methacholine dose-response curves were expressed as the provocative concentration causing 20% fall in FEV1 (PC20). A maximal response plateau was considered if > or = 3 highest doses fell within a 5% response range, the maximal response (MFEV1) being the average value on the plateau. The P-V curves were characterized by an index of compliance (exponent K), and elastic recoil pressures at 90, and 100% of TLC (PL90 and PLmax). In all subjects a complete dose-response curve to methacholine could be recorded. MFEV1 was significantly correlated with logPC20 (r = -0.94, p < 0.001), but not with baseline FEV1 (r = -0.53, p > 0.15). There was a significant relationship between MFEV1 and PL90 (r = -0.79, p < 0.02), PLmax (r = -0.87, p < 0.005), and K (r = 0.79, p < 0.02). Furthermore MFEV1 was significantly correlated with DLCO/VA (r = -0.76, p < 0.03) and with lung density (r = 0.78, p < 0.04). We conclude that in subjects with alpha1-antitrypsin deficiency the level of maximal airway narrowing increases with loss in lung elasticity, with reduction in diffusing capacity, and with lowered mean lung density. This suggests that loss in elastic recoil pressure secondary to parenchymal destruction contributes to excessive airway narrowing in humans in vivo.

Adult↗
PubMed1995

Rhinovirus inhalation causes long-lasting excessive airway narrowing in response to methacholine in asthmatic subjects in vivo.

Exacerbations of asthma are often associated with respiratory infections, and particularly those caused by rhinovirus. The causative role of rhinovirus in these acute episodes is still unclear, since it has not been determined whether or not infection with the virus promotes excessive airway narrowing in asthma. We tested the hypothesis that experimental infection with inhaled wild-type rhinovirus 16 (RV16) increases the maximal degree of airway narrowing in response to bronchoconstrictor stimuli in patients with mild to moderate asthma. Fourteen nonsmoking subjects with atopic asthma and normal FEV1 values participated in a double-blind, placebo-controlled, parallel study. A total dose of 3 x 10(4) of the 50% tissue-culture-infective dose (TCID50) of RV16 or a placebo was administered by pipette, atomizer, and nebulizer in equal doses into both nostrils on two consecutive days. Dose-response curves for inhaled methacholine were recorded 1 d before and 2, 7, and 15 d after RV16 infection or placebo. The response to methacholine was measured by the percent decrease in FEV1, and the maximal degree of airway narrowing was expressed by the average response on the plateau of the dose-response curve. In the seven subjects receiving the virus, RV16 infection was confirmed in nasal washings and/or by an increase in antibody titer, whereas these tests were negative in the placebo group. There was no significant change in baseline FEV1 during the study in either group (p = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A pneumatic artificial larynx popularized in Hong Kong.

The 'Taiwan tube' is an inexpensive pneumatic artificial larynx made in Taiwan. The device, which is a tracheo-oral shunt containing a resonator, is popular with laryngectomees in Hong Kong. This paper reports its use and describes its working dynamics which compare favourably with those of other forms of voice restoration.

Adult↗
PubMed1994

Effects of inhaled substance P on airway responsiveness to methacholine in asthmatic subjects in vivo.

We tested the hypothesis that the inhaled tachykinin substance P (SP) can induce hyperresponsiveness to methacholine in asthmatic subjects in vivo. Nine atopic nonsmoking asthmatic males with normal forced expiratory volume in 1 s (FEV1; > 80% predicted) and increased methacholine sensitivity [provocative concn causing 20% fall in FEV1 (PC20) < 8 mg/ml] participated in a two-period placebo-controlled crossover study. Dose-response curves to SP (0.25-8 mg/ml) and placebo were recorded on 2 randomized days at least 1 wk apart, and methacholine tests were done 24 h before and 2 and 24 h after these challenges. The responses were measured by FEV1 (%fall from baseline). The position of the methacholine dose-response curves was expressed by the PC20 FEV1 and by the maximal response by the plateau level (MFEV1). SP caused a dose-dependent fall in FEV1 (P < 0.001). There was a slight increase in the PC20 FEV1 at 2 and 24 h, which was not significantly different between placebo and SP. Similarly, there was a reduction in MFEV1 at 2 h after both pretreatments. However, at 24 h after SP inhalation, MFEV1 increased compared with placebo. These changes in MFEV1 were significantly different between SP and placebo by 5.2 +/- 2.2% fall (SE) (P < 0.05). We conclude that 1) a bronchoconstrictive dose of SP, compared with placebo, enhances maximal airway narrowing to methacholine in asthma 24 h after inhalation and 2) tolerance develops to high doses of inhaled methacholine. These findings are suggestive of a role of SP in causing excessive airway narrowing in asthma by inflammatory mechanisms.

Administration, Inhalation↗
PubMed1994

Biochemical composition of collagen in continent and stress urinary incontinent women.

This study was designed to assess the relationship between the amount of collagen type III in the pelvic supportive tissues and stress urinary incontinence (SUI) with or without pelvic relaxation. Fourteen women agreed to participate in the study: 6 had stress urinary incontinence and pelvic relaxation (group 1); 4 had no pelvic relaxation and no sign or symptoms of SUI (group 2); 4 had pelvic relaxation without SUI (group 3). All patients underwent gynecologic surgical procedures for benign pathology and at that time biopsies were taken from perineal skin, uterosacral ligaments and round ligaments of the uterus. Collagen type III content was measured in the specimens and compared between the groups. Each subject preoperatively underwent complete urodynamic workup. A t test was used for the statistical analysis. Collagen type III content was significantly reduced (p < 0.05) in the specimens from patients with SUI (group 1) as compared independently with each of the other two groups (groups 2 and 3). Tissues from women without SUI (groups 2 and 3) had a similar content of collagen type III. These findings suggest that women with SUI show an altered collagen profile in the skin, the uterosacral, and the round ligaments. This seems unrelated to secondary damage of the supportive tissues and degree of pelvic relaxation.

Adult↗
PubMed1994

Dermal fibroblasts activate keratinocyte outgrowth on collagen gels.

The effects of dermal fibroblasts on keratinocyte outgrowth on collagen substrata was studied using an in vitro keratinocyte-collagen gel composite model. Skin fibroblasts were seeded inside collagen gels, which remained attached to the cell culture plastic substratum. Fibroblasts incorporated in collagen gels were either kept viable throughout the study, or were lysed hypotonically with water at different time intervals (2 hours and 5 days). Results show that very little keratinocyte outgrowth occurred on either plain collagen gels or gels that had previously contained viable fibroblasts for 2 hours. A 3- to 4-fold increase in keratinocyte outgrowth occurred on collagen gels that had previously contained viable fibroblasts for 5 days. A striking increase (20-fold) in keratinocyte outgrowth was observed on collagen gels that contain viable fibroblasts. The effect of fibroblast diffusible factors on keratinocyte outgrowth was further studied with a co-culture system using Millicell inserts. It was found that the co-culture of fibroblasts with the composite enhanced keratinocyte outgrowth on collagen gels that had previously contained viable fibroblasts for 5 days. Among all, however, the keratinocyte outgrowth was far better on gels containing viable fibroblasts. Addition of keratinocyte growth factor or its neutralizing antibody did not affect keratinocyte outgrowth. These results suggest that dermal fibroblasts can activate keratinocyte outgrowth on collagen matrices through some diffusible factors other than keratinocyte growth factor, and epithelial-mesenchymal interactions exert some special effects on keratinocyte outgrowth on collagen gels.

Cell Communication↗
PubMed1993

Neutral endopeptidase activity and airway hyperresponsiveness to neurokinin A in asthmatic subjects in vivo.

In a previous study we have shown that inhibition of the endogenous neuropeptide-degrading enzyme, neutral endopeptidase (NEP), potentiates airway narrowing to neurokinin A (NKA) in normal humans in vivo. In the present study, we tested the hypothesis that hyperresponsiveness to NKA in asthma is caused by a reduction in endogenous NEP activity. To that end, we used the NEP inhibitor, thiorphan, or placebo as inhaled pretreatment to NKA challenge in eight atopic asthmatic men, who were controlled by on-demand usage of beta 2-agonists alone. The dose of thiorphan pretreatment was obtained from pilot experiments in which 0.5 ml of a 2.5-mg/ml concentration appeared to be the maximally effective nebulized dose. Dose-response curves to inhaled NKA (1 to 125 micrograms/ml, 0.5 ml/dose) were recorded on 2 randomized days 1 wk apart, in a cross-over study. To detect any effects of thiorphan on bronchoconstriction per se, we also investigated the effect of thiorphan or placebo on the dose-response curve to inhaled methacholine in a separate set of experiments. The response was measured by FEV1 and by partial expiratory flow-volume curves (V40p). The position of the dose-response curves was expressed as the concentration causing a 20% fall in FEV1 (PC20FEV1) or a 40% fall in V40p (PC40V40p). Baseline FEV1 and V40p were not affected by either pretreatment (p > 0.06). PC20FEV1 and PC40V40p to NKA were significantly lower after thiorphan pretreatment as compared with placebo (mean difference +/- SEM: 2.3 +/- 0.6 and 1.6 +/- 0.5 doubling dose, respectively; p < 0.015).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long-term effects of a long-acting beta 2-adrenoceptor agonist, salmeterol, on airway hyperresponsiveness in patients with mild asthma.

BACKGROUND: Asthma is characterized by hyperresponsiveness of the airways to bronchoconstrictive stimuli. Long-acting beta 2-adrenoceptor agonists have been introduced as a new therapeutic approach, but there is growing concern about whether control of asthma may deteriorate with the regular use of these agents. We investigated the long-term effects of the beta 2 agonist salmeterol on bronchodilation and on airway hyperresponsiveness to the bronchoconstrictive agent methacholine in mild asthma. METHODS: In a parallel, double-blind study, 24 patients with mild asthma were randomly assigned to treatment with either inhaled salmeterol (50 micrograms, twice daily) (n = 12) or placebo (n = 12) during an eight-week trial. Methacholine challenge was performed before, during, and after the treatment period. Methacholine responsiveness was measured as the provocative concentration (PC20) that caused a 20 percent decrease in the forced expiratory volume in one second (FEV1). RESULTS: There was a significant increase in FEV1 one hour after the inhalation of salmeterol (P = 0.006), which did not differ significantly on days 0, 28, and 56 of the treatment period (increase, 9.8, 9.4, and 8.8 percent of predicted FEV1, respectively; P = 0.91). On the first treatment day, salmeterol afforded significant protection against methacholine-induced bronchoconstriction, as shown by a 10-fold increase in the PC20 as compared with the value at entry (P less than 0.001). After four and eight weeks of treatment, however, the salmeterol-induced change in the PC20 was significantly attenuated (P less than 0.001) to only a twofold increase. Two and four days after treatment ended, the PC20 was not significantly different from the value before treatment (P = 0.15). CONCLUSIONS: Regular treatment of patients with mild asthma with salmeterol leads to tolerance to its protective effects against a bronchoconstrictor stimulus, in this case inhaled methacholine, despite well-maintained bronchodilation. This finding raises concern about the effectiveness of prolonged therapy with long-acting beta 2-adrenoceptor agonists in asthma.

Adrenergic beta-Agonists↗
PubMed1992

Independent regulation of plasminogen activator inhibitor 2 and plasminogen activator inhibitor 1 in human synovial fibroblasts.

OBJECTIVE: To study the plasminogen activator inhibitor(s) (PAI) produced in vitro by human synovial fibroblast-like cells. METHODS: Human synovial cell explant cultures were established using cells from nonrheumatoid donors. PAI-2 and PAI-1 antigens were measured by enzyme-linked immunosorbent assay, and messenger RNA (mRNA) levels were determined by Northern blot. RESULTS: The synovial fibroblasts produced both PAI-2 and PAI-1. Interleukin-1 (IL-1) increased PAI-2 but decreased PAI-1 formation, both at the protein and the mRNA levels. Using cyclooxygenase inhibitors, evidence was obtained that an endogenous cyclooxygenase product(s) in the IL-1-treated cultures inhibited formation of both PAIs; exogenous prostaglandin E2 (10(-7) M) reversed the effect of cyclooxygenase inhibition. The glucocorticoid dexamethasone (10(-6) to 10(-7) M) inhibited IL-1-stimulated PAI-2 formation but reversed the suppressive effect of IL-1 on PAI-1 production. CONCLUSION: PAI-2 formation and PAI-1 formation can be regulated independently in human synoviocytes, illustrating the complexity of the modulation of the net PA activity expressed by these cells.

Blotting, Northern↗
PubMed1992

The effect of an inhaled neutral endopeptidase inhibitor, thiorphan, on airway responses to neurokinin A in normal humans in vivo.

Neuropeptides such as neurokinin A (NKA) have been proposed as important mediators of bronchoconstriction and airway hyperresponsiveness in asthma. Inhaled NKA causes bronchoconstriction in patients with asthma, but not in normal subjects. This is possibly due to the activity of an endogenous neuropeptide-degrading enzyme: neutral endopeptidase (NEP). We investigated whether a NEP-inhibitor, thiorphan, reveals bronchoconstriction to NKA or NKA-induced changes in airway responsiveness to methacholine in normal humans in vivo. Eight normal male subjects participated in a double-blind crossover study, using thiorphan as pretreatment to NKA challenge. Dose-response curves to inhaled NKA (8 to 1,000 micrograms/ml, 0.5 ml/dose) were recorded on 2 randomized days 1 wk apart, and methacholine tests were performed 48 h before and 24 h after the NKA challenge. Ten minutes prior to NKA challenge the subjects inhaled either thiorphan (2.5 mg/ml, 0.5 ml) or placebo. To detect a possible nonspecific effect of thiorphan, we investigated the effect of the same pretreatment with thiorphan or placebo on the dose-response curve to methacholine in a separate set of experiments. The response was measured by the flow from standardized partial expiratory flow-volume curves (V40p), expressed in percent fall from baseline. NKA log dose-response curves were analyzed using the area under the curve (AUC) and the response to the highest dose of 1,000 micrograms/ml (V40p,1000). The methacholine dose-response curves were characterized by their position (PC40V40p) and the maximal-response plateau (MV40p). Baseline V40p was not affected by either pretreatment (p greater than 0.15).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Renal handling of cisplatin: interactions with organic anions and cations in the dog.

Cis-diamminedichloroplatinum (II) (cisplatin CDDP) is an extremely potent chemotherapeutic agent. Its efficacy, however, is hindered by the cumulative dose-dependent nephrotoxicity which can lead to permanent renal impairment. The mechanisms of the renal transport of cisplatin are not clear. As a first step towards understanding the renal handling of cisplatin we studied its renal clearance in dogs, as well as the effects of organic anion and cation administration on cisplatin. Our results document net tubular secretion of cisplatin. Both an organic anion (probenecid) and cations (quinidine, cimetidine, ranitidine) significantly decreased renal clearance of free CDDP without affecting GFR.

Animals↗
PubMed1988

Ambulatory blood pressure measurements: practical considerations, methodology, feasibility, and implications in the management of hypertension.

Automated ambulatory blood pressure monitoring is a safe new technique that allows a more exact assessment of the diagnosis and treatment of hypertension than has been possible previously. It should be of great value in helping avoid unnecessary pharmacologic treatment of certain patients and in tailoring therapy to individual needs. Further research is needed to determine the role of ambulatory monitoring in the detection of hypertension, in the assessment of cardiovascular symptoms, and in the definition and treatment of labile hypertension. Because this technique has been developed subsequent to the research that underlies our current understanding of the effect of hypertension and the treatment of hypertension on cardiovascular disease, further prospective studies are needed to confirm its value in predicting hypertensive complications. A growing body of evidence indicates that ambulatory blood pressure may be a much more powerful predictor of cardiovascular risk than conventional blood pressure measurements.

Ambulatory Care↗
PubMed1987

Chemically modified collagen: a natural biomaterial for tissue replacement.

Glutaraldehyde crosslinking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation. Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable crosslinks. Tissues crosslinked with glutaraldehyde retain many of the viscoelastic properties of the native collagen fibrillar network which render them suitable for bioprostheses. Implants of collagenous materials crosslinked with glutaraldehyde are subject long-term to calcification, biodegradation, and low-grade immune reactions. We have attempted to overcome these problems by enhancing crosslinking through bridging of activated carboxyl groups with diamines and using glutaraldehyde to crosslink the epsilon-NH2 groups in collagen and the unreacted amines introduced by aliphatic diamines. This crosslinking reduces tissue degradation and nearly eliminates humoral antibody induction. Covalent binding of diphosphonates, specifically 3-amino-1-hydroxypropane-1, 1-diphosphonic acid (3-APD), and chondroitin sulfate to collagen or to the crosslink-enhanced collagen network reduces its potential for calcification. Platelet aggregation is also reduced by glutaraldehyde crosslinking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen. The cytotoxicity of residual glutaraldehyde--leaching through the interstices of the collagen fibrils or the tissue matrix--and of reactive aldehydes associated with the bound polymeric glutaraldehyde can be minimized by neutralization and thorough rinsing after crosslinking and storage in a nontoxic bacteriostatic solution.

Adenosine Diphosphate↗
PubMed1984

A 24 year survey of amputees in Hong Kong.

A 24-year retrospective study of amputees was conducted at the Prosthetic and Orthotic Unit of the Kowloon Rehabilitation Centre, the first and largest rehabilitation centre in Hong Kong. A review was made of 1821 patients and a rising trend of amputee population was demonstrated probably related to the population growth. The ratio of lower limb to upper limb amputees was 1.83 to 1. The mean age of the amputees was 39 years. The commonest cause of upper limb amputation was trauma (89%) and of lower limb amputation was infection (35%). Vascular diseases were not as common in Chinese as in Caucasian communities. These patterns of amputee population indicate the demand for prosthetic service and provide guide-lines for future development.

Adolescent↗