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Biomedical subjects

H Y Wong

Publications and source records attributed to H Y Wong.

At least 19 recordsLinked to original sources
PubMed1997

Treatment options in struvite stones.

Urinary calculi have plagued man over the centuries. The epidemiology and pathogenesis of infection have been studied. The curative treatment remains problematic. Without therapy, a vicious cycle of stone formation occurs. This results in renal damage and even death. Multimodality therapy is the key. Nonoperative treatment leads to progressive renal damage. The combination of maximal surgical ablation and medical therapy is synergistic. The combination of PCNL-ESWL has not appeared to produce ill effects. PCNL-ESWL is a less morbid surgical alternative than open surgical procedures. Adjunctive medical therapy, such as culture-specific antibiotics and urease inhibitors, complements surgical ablation by reducing the morbidity with persistent UTIs and stone recurrence. The urologist today must approach struvite staghorns with a vast armamentarium of surgical and medical techniques. Each patient requires a unique solution.

Humans↗
PubMed1996

Electromotive administration of intravesical lidocaine in patients with interstitial cystitis.

Six patients with long-standing interstitial cystitis (IC) were treated with intravesical electromotive drug-assisted (EMDA) therapy using lidocaine (1.5%) and 1:100,000 epinephrine in aqueous solution. A stainless-steel silver-coated anode placed through an 18F Foley catheter was positioned in the urinary bladder, and a 5 x 10-cm dispersion electrode (cathode) was placed on the suprapubic skin, which was well lubricated with conductive jelly. The two electrodes were connected to a pulsed DC generator, and electrical current was slowly ramped from 0 to 15 mA while the lidocaine and epinephrine were in the urinary bladder. After 40 minutes of current application, the bladder was hydraulically dilated to maximum tolerance. Significant bladder dilatation was achieved without systemic symptoms. Post-treatment, voiding symptoms decreased, as did suprapubic and perineal pain, and in four patients, the results have been durable.

Administration, Intravesical↗
PubMed1996

Electromotive drug administration to the urinary bladder: an animal model and preliminary results.

PURPOSE: Electromotive drug delivery (EMDA) is the use of an electrical field to enhance penetration of ionized drugs into local tissues. Intraurinary EMDA may be of value in the treatment of various pathological conditions involving the urinary bladder, prostate gland and urethra. We have developed an animal model to study this hypothesis. MATERIALS AND METHODS: Anesthetized adult mongrel dogs were studied. An intravesical anode was inserted through a Foley catheter into the urinary bladder. Two patch electrodes were positioned on the animals' abdominal skin. Both skin and intravesical electrodes were attached to a direct current generator. The bladder was then distended with an anionic blue dye (methylene blue). Fifteen milliamperes (15 mA) pulsed direct current was applied for 40 minutes. After EMDA, the bladder was surgically removed and representative sections of full thickness bladder wall were immediately frozen in liquid nitrogen. Methylene blue was used to visually demonstrate EMDA-enhanced anion penetration into bladder submucosa and muscularis. RESULT: This experimental model demonstrates significant submucosal and muscularis methylene blue penetration in the presence of the electric field. CONCLUSION: Electromotive drug delivery technology may have applications for treating bladder pathology.

Administration, Intravesical↗
PubMed1995

Retrograde nephrostomy: advantages, disadvantages, and the learning curve.

Establishment of a nephrostomy tract is a prerequisite for many endourologic procedures of the upper urinary tract. We reviewed our initial experience with 31 retrograde nephrostomies to determine the advantages and disadvantages and the learning curve for the procedure. All but one of the attempts were successful, and no complications were attributable to the nephrostomy puncture. The procedure time averaged 21.1 minutes in nondilated collecting systems but 32.0 minutes in hydronephrotic kidneys (P < 0.01). The mean procedure time in our first 10 successful cases was 36.2 minutes, but it decreased to 22.6 minutes in the second 10 successful cases (P < 0.02). Radiation exposure was also minimized early, with a mean fluoroscopy time of 3.5 minutes in our first 10 successful cases and 1.5 minutes in our second 10 successful cases (P < 0.02). Similarly, both procedure and fluoroscopy times decreased further in the most recent 10 successful cases. Retrograde nephrostomy is a safe procedure, is easier in a nondilated collecting system, and can be mastered with a short learning curve with minimal radiation exposure.

Adolescent↗
PubMed1995

The effect of iontophoresis on bacterial growth in urine.

PURPOSE: To determine the effect of iontophoresis (electrical current for therapeutic purposes) on the growth of pathogenic bacteria in human urine. MATERIALS AND METHODS: Pathogenic bacteria were isolated and inoculated into a dynamic in vitro artificial bladder model. Pooled sterile human urine was regulated through the artificial bladder by intravenous tubing and pumps to simulate filling and emptying of the human bladder. The effect of electrical current on bacterial growth in the system was then studied. RESULTS: When iontophoresis is applied at low bacterial concentrations ( < 10(8) colony forming units [CFU]/l.), inhibition of bacterial growth occurs. However, when iontophoresis is applied after fulminant growth of bacteria ( > 10(8) CFU/l.), no inhibition of bacterial growth occurs. Iontophoresis was not found to enhance the antibacterial action of gentamicin to resistant Pseudomonas aeruginosa. CONCLUSIONS: Iontophoresis inhibits bacterial growth at low bacterial concentrations. It does not inhibit bacterial growth after infectious levels have been attained, and it does not potentiate the action of gentamicin on resistant Pseudomonas aeruginosa.

Equipment Design↗
PubMed1994

Laparoscopy.

Explore the source record for details and available documents.

Humans↗
PubMed1994

The effect of low-dose bupivacaine on postoperative epidural fentanyl analgesia and thrombelastography.

We performed a prospective, randomized, double-blind study to determine the effect of bupivacaine on postoperative epidural fentanyl analgesia and thrombelastography in 120 patients who underwent extensive gastrointestinal or genitourinary surgery. The patients were randomized into four groups, 30 patients per group: Group I = epidural fentanyl (EF), 10 micrograms/mL in saline; Group II = EF with 0.1% bupivacaine; Group III = EF with 0.15% bupivacaine; and Group IV = EF with 0.2% bupivacaine. Pain relief was evaluated by a visual analog scale (VAS), both at rest and during coughing, and by a visual rating scale (VRS). The VAS, VRS, degree of sedation, and side effects (nausea, vomiting, and pruritus) were evaluated every 2 h from 8:00 AM to 6:00 PM, for 24 h after surgery. Forced vital capacities (FVCs) were determined before surgery and at 24 h after surgery. Blood was withdrawn for thrombelastography (TEG) measurements preoperatively, in the recovery room (PARR), and 24 h postoperatively. The VAS, VRS, sedation scores, changes in postoperative FVCs, and the incidence of side effects were not statistically different among the four groups. The 24-h total volumes of infusion in the four groups (146 +/- 40 mL, 140 +/- 38 mL, 142 +/- 40 mL, 124 +/- 21 mL, respectively) were not statistically different from each other. There were no significant differences in the TEG values [reaction time (R), coagulation time (K), angle (alpha), and maximum amplitude (mA)] among the four groups at anytime nor was there any difference between the baseline, PARR, and 24-h TEG values within any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A randomized, double-blind evaluation of ketorolac tromethamine for postoperative analgesia in ambulatory surgery patients.

BACKGROUND: Given the trend toward early discharge of patients after surgery and the inherent adverse effects of opioid analgesics, we compared a new nonsteroidal antiinflammatory drug, ketorolac tromethamine, given intravenously (iv) and then orally, with two commonly prescribed opioid analgesics in ambulatory patients for up to 1 week after surgery. METHODS: In this study incorporating a double-blind, multi-dose design, 221 patients who had moderate or severe pain after surgery were randomized to one of three treatment groups: group K30 received 30 mg iv ketorolac twice, then 10 mg iv every 30 min as required to control pain, up to six doses, followed by 10 mg oral ketorolac every 4-6 h; group F50 received 50 micrograms iv fentanyl at the same time intervals as in group K30, followed by 60 mg codeine plus 600 mg acetaminophen (C+A) orally every 4-6 h; and group F10 received the same combination as did group F50, but only 10 micrograms fentanyl per dose. RESULTS: Compared with 50 micrograms fentanyl iv, 30 mg iv ketorolac provided delayed but otherwise equivalent analgesic effects and was associated with similar side effects. Compared with C+A, 10 mg oral ketorolac was associated with a lower incidence of nausea and somnolence and earlier return of bowel function but not better pain relief, drug tolerability, quality of life, or psychologic well-being. CONCLUSIONS: Ketorolac, when used in an iv and then oral sequence, is a safe and effective analgesic in the ambulatory surgery setting. It has a slower onset than fentanyl, but causes fewer side effects than C+A.

Administration, Oral↗
PubMed1993

Effect of atherogenic diet on chicken plasma lipids and lipoproteins.

Adult male White Leghorn chickens were used in an experimental model system to study atherogenesis, and the effects of an atherogenic diet on plasma lipoprotein composition including carotenoids were determined. This model also included treatment with diazepam, a drug known to reduce formation of atherogenic plaques. After 6 wk consumption of a high-cholesterol, high-triglyceride diet, chickens had mean total plasma cholesterol, triglyceride, and carotenoid concentrations that were significantly increased over those from chicks that consumed the standard diet. Diazepam treatment had no significant effect on whole plasma concentrations of these lipids. Total body weight gain was unaffected by diet, but liver weight expressed as percentage of body weight was significantly increased in chickens that consumed the atherogenic diet. High density lipoprotein (HDL) and low density lipoprotein (LDL) fractions were isolated from plasma samples by ultracentrifugation. The atherogenic diet increased the carotenoid, cholesterol, and protein content of the LDL fractions but not the HDL fractions.

Animals↗
PubMed1993

Neural mechanisms of joint pain.

Joint pain is a common symptom in various forms of arthritis. Unfortunately, the mechanisms involved in the pathogenesis of joint pain are not well understood, but probably include peripheral and central neural mechanisms. The sympathetic system appears to interact with sensory afferents under pathological conditions, and this may be mediated directly via receptors on sensory neurons, or indirectly via inflammatory mediators. Classical inflammatory mediators such as serotonin and bradykinin appear to activate some nociceptive afferents and serotonin may sensitise these afferents to non-noxious stimuli in an inflamed joint. A purely sensory function has traditionally been ascribed to sensory afferents, but unmyelinated C fibres have in addition a neurosecretory role and release peptides such as substance P which may contribute to inflammation. Lastly, central sensitisation in the spinal cord may play an important role in the pathogenesis of joint pain. Activation of N-Methyl-D-Aspartate (NMDA) receptors and the wind-up phenomenon may be involved in central sensitisation.

Afferent Pathways↗
PubMed1993

A randomized double-blind comparison of epidural fentanyl infusion versus patient-controlled analgesia with morphine for postthoracotomy pain.

The authors conducted a prospective, randomized, double-blind comparison of an epidural fentanyl infusion versus patient-controlled analgesia (PCA) with morphine in the management of postthoracotomy pain. Thirty-six patients were randomized into one of two groups. The epidural group received an epidural fentanyl infusion, 10 micrograms/mL, and saline through their PCA machine. The PCA group received an epidural saline infusion and morphine, 1.0 mg/mL, through their PCA device. The infusions were escalated according to a study protocol when pain relief was deemed inadequate by the patients. Pain relief was evaluated by a visual analog pain scale (VAS), both at rest and during coughing, and by verbal rating scores (VRS) of pain relief. Degree of sedation and the frequency of nausea, vomiting, and pruritus were also noted. The VAS, VRS, degree of sedation, and side effects were evaluated every 2 h from 7 AM to 7 PM, for 72 h after surgery. Forced vital capacities were determined before surgery and at 24, 48, and 72 h after surgery. The VAS were significantly lower (P = 0.001), and the Total Pain Relief scores higher (P < 0.02) in the epidural group, signifying better analgesia. There were no differences in postoperative forced vital capacity between the two groups. More patients in the PCA group had greater degrees of sedation on postoperative day 1 (P = 0.005), whereas pruritus was more frequent (P < 0.02) in the epidural group. We conclude that an epidural fentanyl infusion is superior to that of PCA with morphine in the management of pain after thoracotomy.

Aged↗
PubMed1992

Social stress and atherosclerosis in roosters.

1. Socially stressed roosters fed either plain mash or an atherogenic diet had a greater incidence and severity of aortic atherogenesis than similarly fed non-stressed birds. 2. Results demonstrated a significant atherogenic effect of stress in chickens even in the absence of hyperlipidaemia. 3. Lack of appreciable differences in plasma lipids between stressed and non-stressed birds suggested that the atherogenic effects of stress may be attributable to neuroendocrine responses. 4. Levels of HDLc of plain mash groups were significantly higher than in the atherogenic fed groups. 5. Haemodynamic data showed no treatment-related differences.

Animals↗
PubMed1992

Stroke subtypes among Chinese living in Hong Kong: the Shatin Stroke Registry.

The Shatin Stroke Registry is a prospective study of all patients admitted with acute stroke to a general hospital in Hong Kong where the population is predominantly Chinese. Each patient was examined by a neurologist and 95.5% of the patients had a brain CT. Of 777 patients included in the study, 44.0% had a cortical/subcortical infarct, 18.5% a supratentorial lacunar infarct, 24.2% a supratentorial intracerebral hemorrhage, 5.8% brainstem/cerebellar infarct, 2.9% a brainstem/cerebellar hemorrhage, and 4.5% an uncertain diagnosis. The overall 30-day case fatality rate was 25.4%. Comparison with five stroke registries from the West suggests that intracerebral hemorrhage occurs between two and three times more frequently in the Chinese than in Westerners. Whether there is any difference in the relative frequencies for lacunar infarction remains unclear.

Adult↗
PubMed1992

Effects of diazepam (Valium) on aortic atherogenesis and plasma lecithin: cholesterol acyltransferase activity in cockerels fed an atherogenic diet.

Blood plasma LCAT (lecithin: cholesterol acyltransferase, EC 2.3.1.43) was studied in cockerels fed an atherogenic diet to determine if attenuation of aortic atherogenesis, as a result of simultaneous treatment of the birds with diazepam, might be related to modulation of enzyme activity by the drug. Administration of diazepam (0.6 mg/kg) did not influence LCAT. It was observed that no relationship could be established between enzyme activity and the extent of aortic atherogenesis. In contrast, addition of diazepam in vitro to cockerel plasma caused a concentration-dependent inhibition of LCAT activity. The effect was most pronounced when diazepam was present at a concentration of 50-200 microM, where inhibition of enzyme activity was 25-65%. Thus, pharmacologic doses of diazepam do not appear to affect LCAT in vivo. It is concluded that diazepam attenuates aortic atherogenesis in cockerels fed an atherogenic diet by a mechanism independent of LCAT.

Animals↗
PubMed1991

Enhanced choline and Rb+ transport in human erythrocytes infected with the malaria parasite Plasmodium falciparum.

Human erythrocytes infected in vitro with the malaria parasite Plasmodium falciparum showed a markedly increased rate of choline influx compared with normal cells. Choline transport into uninfected cells (cultured in parallel with infected cells) obeyed Michaelis-Menten kinetics (Km approximately 11 microM). In malaria-parasite-infected cells there was an additional choline-transport component which failed to saturate at extracellular concentrations of up to 500 microM. This component was less sensitive than the endogenous transporter to inhibition by the Cinchona bark alkaloids quinine, quinidine, cinchonine and cinchonidine, but showed a much greater sensitivity than the native system to inhibition by piperine. The sensitivity of the induced choline transport to these reagents was similar to that of the malaria-induced (ouabain- and bumetanide-resistant) Rb(+)-transport pathway; however, the relative magnitudes of the piperine-sensitive choline and Rb+ fluxes in malaria-parasite-infected cells varied between cultures. This suggests either that the enhanced transport of the two cations was via functionally distinct (albeit pharmacologically similar) pathways, or that the transport was mediated by a pathway with variable substrate selectivity.

Animals↗
PubMed1991

Dose-finding study of intramuscular midazolam preanesthetic medication in the elderly.

Intramuscular midazolam frequently results in excessive sedation in elderly patients. The effects of preanesthetic medication with intramuscular midazolam were examined in 100 elderly patients, aged 60-86 yr, given 1, 2, or 3 mg midazolam or placebo using a randomized, double-blind study design. Level of sedation and anxiety were assessed every 15 min for 1 h. Picture cards were presented at the same times in order to assess recall of these cards 24 h later. All three doses of midazolam produced rapid onset of sedation, anxiolysis, and anterograde amnesia. These effects decreased in intensity by 60 min after drug injection. The intensity and extent of these effects were comparable with those reported with higher doses in younger patients, although with the 1-mg midazolam dose the effects were shorter-lived, and a difference from placebo was not consistently seen. Three patients (3%), all older than 70 yr, became unresponsive to vocal and tactile stimuli. This level of drowsiness was unrelated to body weight, age, or ASA physical status. We conclude that in adults between 60-69 yr old, midazolam 2 or 3 mg intramuscularly can be effective as preanesthetic medication without causing excessive drowsiness. However, intramuscular midazolam should be used cautiously, under continuous observation, in patients aged 70 yr and older because excessive drowsiness may occur.

Aged↗
PubMed1991

Hypertension, lipoprotein(a), and apolipoprotein A-I as risk factors for stroke in the Chinese.

We analyzed the serum concentrations of lipids and lipoproteins and the prevalence of other risk factors in a case-control study of 304 consecutive Chinese patients with acute stroke (classified as cerebral infarction, lacunar infarction, or intracerebral hemorrhage) and 304 age- and sex-matched controls. For all strokes we identified the following risk factors: a history of ischemic heart disease, diabetes mellitus, or hypertension; the presence of atrial fibrillation or left ventricular hypertrophy; a glycosylated hemoglobin A1 concentration of greater than 9.1%; a fasting plasma glucose concentration 3 months after stroke of greater than 6.0 mmol/l; a serum triglyceride concentration 3 months after stroke of greater than 2.1 mmol/l; and a serum lipoprotein(a) concentration of greater than 29.2 mg/dl. We found the following protective factors: a serum high density lipoprotein-cholesterol concentration of greater than 1.59 mmol/l and a serum apolipoprotein A-I concentration of greater than or equal to 106 mg/dl. The patterns of risk factors differed among the three stroke subtypes. When significant risk factors were entered into a multiple logistic regression model, we found a history of hypertension, a high serum lipoprotein(a) concentration, and a low apolipoprotein A-I concentration to be independent risk factors for all strokes. The attributable risk for hypertension was estimated to be 24% in patients aged greater than or equal to 60 years. In this population, in which cerebrovascular diseases are the third commonest cause of mortality, identification of risk factors will allow further studies in risk factor modification for the prevention of stroke.

Apolipoprotein A-I↗