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Biomedical subjects

L Wong

Publications and source records attributed to L Wong.

At least 163 records · Page 9Linked to original sources
PubMed1993

Sunlight exposure, antioxidant status, and cataract in Hong Kong fishermen.

STUDY OBJECTIVES: The aim was to test whether cataract is associated with higher lifetime exposure to sunlight, and whether antioxidants protect against cataract. DESIGN: This was a cross sectional survey of eye disease, with assessment of antioxidant status in a subgroup. SETTING: Hong Kong fishing communities in 1989. PARTICIPANTS: 685 men and women aged 55 to 74 years old were included in the study, of whom 367 (54%) attended hospital for detailed examination. MEASUREMENTS AND MAIN RESULTS: At a mobile clinic visual acuity and lens opacities were assessed, and using a questionnaire, occupational history and lifetime exposure to sunlight. At hospital ophthalmic measurements were repeated and blood was taken for measurement of plasma vitamin C, vitamin E, and total carotenoids, and red cell activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, superoxide dismutase, and catalase. Higher grades of cataract (particularly nuclear cataract) tended to be more common in subjects with the most sun exposure, although not to the point of statistical significance. In contrast to earlier studies, no association was found with antioxidant status. CONCLUSIONS: The findings give some support to the hypothesis that sunlight causes cataract. The absence of a relation to antioxidant status may be because blood levels of antioxidants at one point in time do not adequately reflect a subject's past metabolic state, and particularly the past activity of antioxidants in the lens.

Aged↗
PubMed1993

Education, reading, and familial tendency as risk factors for myopia in Hong Kong fishermen.

STUDY OBJECTIVE: The aim was to assess the influence of childhood reading on the development of myopia after allowance for familial differences in susceptibility. DESIGN: The study was a cross sectional survey. SETTING: Four fishing harbours in Hong Kong in 1989. SUBJECTS: Participants were 408 men and women aged 15-39 years old from 159 families. MAIN RESULTS: Histories of school attendance and reading habits in childhood were obtained at interview. Myopia was assessed by retinoscopy. Associations between myopia (defined as a refractive error of at least -1.0D in one or both eyes) and indices of reading in childhood were explored. Myopia was more common in subjects who had attended school (odds ratio = 1.7, 95% CI 1.0-3.0), with the highest risks in those who had started school at the earliest ages and who had spent the most time reading and writing while at primary school. Allowance for familial tendency to myopia produced no diminution in the risks associated with reading. CONCLUSIONS: These data support the hypothesis that reading in childhood is a cause of short sight.

Adolescent↗
PubMed1993

Improving the bottom line with imaging technology.

Imaging technology creates efficiencies in medical record processing that can positively affect a hospital's bottom line by improving productivity, reducing labor costs, and generating income through accelerated accounts receivable operations and billable copying and correspondence functions.

Accounts Payable and Receivable↗
PubMed1993

Effects of sympathetic denervation and oxygen free radicals on neovascularization in skin flaps.

An island skin flap, with its sole blood supply based on the inferior epigastric vessels, in Sprague-Dawley rats (female, 220 to 250 gm) was used as a model for the investigation of neovascularization. Flap survival after pedicle ligation was considered an indicator of neovascularization. Vascular pedicles were ligated on days 2 to 5 after flap elevation, and the time course of neovascularization in the innervated and denervated flaps was determined by measurements of survival on day 7 after pedicle ligation (on days 9 to 12 postoperatively). Neovascularization sufficient to maintain viability was established at 4 and 5 days after flap elevation in the innervated and denervated flaps, respectively. The effects of various scavengers of oxygen free radicals on neovascularization were evaluated in the innervated and denervated flaps. The pedicles were ligated 3 days after flap elevation. Flap survival was assessed on day 7 after pedicle ligation (on day 10 postoperatively). Treatment with a single dose of deferoxamine (50 mg/kg) increased the viability from 48 to 69 percent of flap area in the denervated flaps (p < 0.01) but produced little effect on viability in the innervated flaps. In the denervated flaps, treatments with a single dose of superoxide dismutase, intravenously and intraarterially, also substantially increased the survival rates from 29 to 86 percent (marginally significant) and 100 percent (p < 0.05), respectively. Allopurinol improved the survival from 43 to 88 percent; the difference was not statistically significant. The results suggest that denervation resulted in a delay of neovascularization and that severe sympathetic denervation contributes to the production of oxygen free radicals, which may exert their inhibitory effects on neovascularization.

Allopurinol↗
PubMed1993

Craniofacial growth following rigid fixation: suture excision, miniplating, and microplating.

The effects of plating the coronal and nasofrontal sutures on skull growth were studied in New Zealand white rabbits. Removal of the underlying coronal suture and reduction in the size of the plate were also studied with regard to their effect on growth. Three-dimensional coordinate landmarks located on the skulls were digitized and analyzed to determine the differences in form between operated and unoperated animals using Euclidian distance matrix analysis. Interlandmark distances in three dimensions were compared to demonstrate changes induced by plating. Coronal suture plating (n = 8) resulted in local decreases in dimensions of the plated bones and contralateral and adjacent skull size increases. Removal of the coronal suture without plating (n = 6) resulted in an increase in the size of the adjacent frontal bone and an increase in the width of the suture. Placement of a plate after removal of the underlying suture (n = 8) resulted in decreases in dimensions of the plated bones, with distant length and width increases in a pattern similar to that of the skulls that were simply plated. Plating across the nasofrontal suture (n = 6) resulted in decreases in dimensions in the plated bone, with some distant width increases at the midfrontal bone, the coronal suture, and the posterior parietal bone. In this group, no contralateral increase in dimensions was detected. This is unlike the pattern observed for the animals with a coronal suture plate only. Placing a microplate across the coronal suture (n = 6) resulted in morphologies similar to those with the use of miniplates across the coronal suture. We propose that the varying morphologies in these groups represent compensatory changes accompanying growth restriction induced by plating. We suggest that the lack of contralateral growth increases with nasofrontal suture plating results from lesser effects on the underlying growing cranial contents at this location, as compared with the coronal suture. We find consistent results despite suture removal, change in plate location, and change in plate size.

Animals↗
PubMed1993

Chronic peripheral lymphatic cannulation in the dog.

Peripheral lymph collected acutely has been commonly sampled as representative of non-visceral interstitial fluid. By developing a prenodal lymphatic-lymphatic (L-L) shunt, we were able to collect peripheral lymph for 3-5 days in unanesthetized dogs. The L-L shunt was constructed entirely of medical grade silicone rubber tubing designed with a slip of coupling which allowed the shunt to be disconnected for lymph collection and reconnected at night. Average peripheral lymph flow (4.9 ml/hr leg) in unanesthetized dogs was almost twice the flow rate previously observed in anesthetized dogs. The average lymph/plasma total protein concentration ratio (0.16), however, was similar to that previously found in anesthetized dogs. Lymph protein concentration fell with the collection during the day and became more concentrated at night. Lymph flow did not change greatly during daytime collection. Average peripheral lymph collection volume was greater than 200 ml/dog. The L-L shunt allows collection of prenodal-lymph in experiments where unanesthetized dogs are required (e.g., feeding studies). They also are useful when multiple protocols are conducted on the same dog or when large volumes of peripheral lymph are required.

Animals↗
PubMed1992

Procedure for development of an enzyme-linked immunosorbent assay. Development of an assay for human apolipoprotein A-I.

A set of criteria for selection of antibodies during the development of enzyme-linked immunosorbent assay (ELISA) is described. Using these criteria, a competitive ELISA for human apo A-I using a polyclonal goat antibody was developed. The assay recognizes apo A-I from plasma and high-density lipoprotein (HDL), as well as the pure delipidated apo A-I, equally. Intra- and inter-assay variations were 5.2% and 3.5%, respectively. Recovery rate, as determined by spiking a known quantity of pure delipidated apo A-I into a reference plasma, was determined to be 101.3%. The assay was validated by comparing the concentration of apo A-I in HDL with the dye elution method. The apo A-I ELISA to apo A-I dye elution ratio was 1.01. Apo A-I concentration in Centers for Disease Control reference material determined by this method was in agreement with the reported consensus value. Repeated freezing and thawing of the samples (three freeze-thaw cycles at -20 degrees C) as well as long-term freezing (up to 1 year at -70 degrees C) did not affect the concentration of apo A-I in the samples. The assay was applicable both to normolipidemic and dyslipidemic plasmas. No immunologic difference was noted when plasma from dyslipidemic subjects was assayed. A frequent problem of long-term storage is deamidation. The values found for apo A-I in a deamidated plasma were the same as those for the corresponding fresh plasma. Plasma apo A-I values were also positively correlated with that of HDL-cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1992

Twelve hundred open cholecystectomies before the laparoscopic era. A standard for comparison.

Records of 1200 consecutive open cholecystectomies, performed by a teaching service of a large, urban hospital in the years immediately preceding the laparoscopic era, were reviewed for morbidity and mortality rates. The mortality rate in this series was 1.8%, chiefly in the older age groups. Only two ductal injuries were incurred. A review of published series from 1952 through 1990 revealed a mean mortality rate of 1.53%. These recent observations on the morbidity and mortality after open operation should provide a useful standard of comparison with ongoing similar studies of laparoscopic cholecystectomy.

Adolescent↗
PubMed1992

BC200 RNA in normal human neocortex, non-Alzheimer dementia (NAD), and senile dementia of the Alzheimer type (AD).

BC200 RNA is a polyadenylated 200 nucleotide primate brain-specific transcript with 80% homology to the left monomer of the human Alu family of repetitive elements. Whether this transcription product contributes anything to normal brain gene function or is a residue of post transcriptional processing of brain heterogeneous nuclear RNA (hnRNA) is uncertain. However, the high abundance, tissue-specific expression and nucleotide sequence characteristics of BC200 RNA suggests that the generation of this small RNA is associated with some brain cell function. Sustained levels of the BC200 RNA transcript may be indicative of a genetically competent and normally functioning cerebral neocortex. In this investigation, we have measured the abundance of the BC200 RNA transcript in total RNA isolated from 18 temporal neocortices (Brodman area 22) of brains with no pathology and those affected with neurodegenerative disease. Neocortices were examined from 3 neurologically normal brains, 5 non-Alzheimer demented [NAD; 3 Huntington's chorea (HC), 1 amyotrophic lateral sclerosis (ALS) and 1 dementia unclassified] and 10 Alzheimer disease (AD) affected brains. Our results indicate a strong BC200 presence in both the normal brains and NAD affected neocortices, but a 70 per cent reduction in BC200 signal strength in AD afflicted brains. These results may be related to the observation that Alzheimer brains exhibit marked deficits in the abundance of neuron-specific DNA transcripts; these deficits are consistent with the idea that AD is characterized by an impairment in the primary generation of brain gene transcription products.

Alzheimer Disease↗
PubMed1992

Congenital bladder rupture and urine ascites secondary to a sacrococcygeal teratoma.

A case of congenital bladder rupture with urine ascites and bilateral hydronephrosis secondary to a sacrococcygeal teratoma obstructing the bladder outlet is presented. As no evidence of pulmonary hypoplasia and renal dysplasia was present, with rapid recovery of renal function after decompressive surgery, the infravesical obstruction probably occurred late in the fetal period. The bladder rupture resulting in internal decompression may have constituted an additional protective mechanism for the preservation of renal function.

Ascites↗
PubMed1992

pH responses to sucrose and the formation of pH gradients in thick 'artificial mouth' microcosm plaques.

Artificial microcosm plaques were grown in a five-plaque culture system for up to 6 weeks, reaching a maximum depth of several mm. Procedures for long-term pH measurement with glass electrodes were established; they showed that the application of 5 or 10% sucrose for 6 min with a slow continuous flow of a basal medium containing mucin (BMM) generated the pH changes characteristic of in vivo Stephan curves. These pH responses were reproducible between plaques. Plaque mass and thickness were critical variables. Successive, sucrose-induced pH curves in plaques up to 4 mm thickness showed minor reductions only in the amplitude and rates of pH change. In plaques over 4 mm thick there was a pronounced reduction in pH response to successive sucrose applications, indicating increased diffusion limitations--a result of plaque growth to seal in the freshly-inserted pH electrode. In plaques of 6 mm maximum thickness, 10% sucrose induced a decrease to below pH 5.5 lasting 24 h, compared to the pH response in 2 mm thick plaque, which returned to the resting pH in 2 h. Differences in pH of up to 0.9 units were identified in thick plaques between inner and outer layers. The BMM flow rate was a critical determinant of the amplitude of the pH response to sucrose and subsequent return to resting pH. These results confirm, for microcosm plaque, the importance of clearance dynamics and diffusion-limited gradients in regulating plaque pH.

Animals↗
PubMed1992

Copulatory behavior, reproduction, and sperm competition in two strains of male rats.

Long-Evans males fathered 72% of the offspring when one Long-Evans and one F344 male mated repeatedly with the same female throughout her estrus. When each male was restricted to one ejaculation and the second male was allowed to begin mating immediately following the first male's ejaculation, the second male left more offspring in each strain. However, the proportion was significantly greater for Long-Evans males. In contrast, there were no strain differences in either number of pregnancies or litter size in noncompetitive matings limited to two ejaculations, the minimal number required to induce pregnancy. The only consistent behavioral differences were the greater number of intromissions performed with shorter latencies by F344 males, differences that cannot readily be used to explain their reduced success. It was hypothesized that the two strains may differ in the adequacy of penile reflexes used to form, set, or dislodge sperm plugs.

Animals↗
PubMed1992

Epidermal nevus: surgical treatment by partial-thickness skin excision.

A child with epidermal nevus, systematized, is reported in which diffuse areas of pruritic and bleeding tissue were treated by partial-thickness skin excision, a technique reported to have been successful in other forms of benign dyskeratosis, such as psoriasis. At age 5 years, a test region of the anterior thigh was treated and remained disease free with an acceptable scar. At age 8 years, this technique was applied to the back, buttock, calf, and thigh. While the areas remain disease free, they have, unfortunately, healed with hypertrophic and keloid scars.

Child↗
PubMed1992

Soft tissue chondroma presenting as a painful finger: diagnosis by magnetic resonance imaging.

Benign cartilage tumors of the hands and feet are uncommon soft tissue tumors that generally present as a painless swelling. The diagnosis is often made histologically, as the radiographic appearance of the soft tissues may be normal. In this report, we present a woman who demonstrates the need to consider soft tissue chondromas in the differential diagnosis of a painful finger. Magnetic resonance imaging was used to localize the tumor, suggesting that this imaging method may be useful in differential diagnosis of finger pain.

Adult↗
PubMed1992

Altered epitope expression of human interstitial fluid apolipoprotein A-I reduces its ability to activate lecithin cholesterol acyl transferase.

In human peripheral interstitial fluid, esterification of cholesterol by lecithin cholesterol acyltransferase (LCAT) was found to occur at a rate of only 10% of that in plasma (5.6 +/- 1.8 compared with 55.6 +/- 7.8 nmol/ml per h). Measurement of cholesterol esterification in the presence of excess reconstituted apoA-I HDL (rA-I HDL) revealed an LCAT activity in interstitial fluid of 24% of that in plasma, indicating that the low rate of esterification could not be caused by limiting mass of LCAT enzyme. When plasma was diluted to the same concentration as in interstitial fluid, the percent cholesterol esterification rate was the same as undiluted plasma and significantly higher than that of interstitial fluid. These findings led us to postulate that poor activation of LCAT in interstitial fluid may result from a change in conformation in apoA-I. To test this hypothesis, a monoclonal antibody AI-11 that inhibits apoA-I activation of LCAT was used to measure apoA-I in interstitial fluid and plasma. Antibody AI-11 recognized interstitial fluid apoA-I poorly, whereas a polyclonal antibody recognized interstitial fluid apoA-I normally. Incubation of antibody AI-11 with high density lipoprotein or rA-I HDL inhibited apoA-I activation of LCAT. We conclude that the altered conformation of apoA-I in interstitial fluid may render it a poor activator of LCAT.

Albumins↗
PubMed1992

Regulation of the hepatic growth hormone receptor and serum growth hormone-binding protein during pregnancy in the mouse: effects of litter size.

The regulation of hepatic GH receptor (GHR) and serum GH-binding protein (GHBP) during pregnancy in the mouse was investigated by manipulating the number of conceptuses carried by the dam. Animals carrying 1-4 conceptuses had significantly lower amounts of hepatic GHR (GH-binding activity) than mice carrying 10-13 conceptuses on days 9 and 13 of pregnancy. There was no significant difference in hepatic GHR on day 17 of pregnancy between animals carrying 1-4 and 10-13 conceptuses. Animals carrying 1-4 conceptuses had significantly lower concentrations of GHBP in serum than animals carrying 10-13 conceptuses on days 9, 13, and 17 of pregnancy. The relative amounts of liver GHR- and GHBP-encoding messages in animals with low and high conceptus numbers were investigated by Northern analysis. There were higher levels of both messages in animals carrying 10-13 conceptuses than in mice carrying 1-4 conceptuses. On day 13 of pregnancy, animals carrying 10-13 conceptuses had significantly higher levels of GHBP-encoding message than animals carrying 1-4 conceptuses. Total hepatic mass was not significantly different between animals with low and high conceptus numbers. No significant difference was found in GHBP concentration between blood from the uterine vein and the trunk in 17-day pregnant animals. Mouse placental lactogen-I (mPL-I), mPL-II, GH, and corticosterone concentrations were measured by RIA and related to hepatic GHR activity and serum GHBP concentration. Hepatic GHR activity and serum GHBP concentration were significantly correlated with each other on days 9, 13, and 17 of pregnancy. Hepatic GHR activity was significantly correlated with mPL-I and mPL-II on day 9 of pregnancy. GHBP concentration was significantly correlated with mPL-I and mPL-II on day 9 of pregnancy and with mPL-II and GH on day 13 of pregnancy. Data are consistent with the hypothesis that mPL-I, mPL-II, and GH may affect hepatic expression of the GHR/GHBP gene during pregnancy in the mouse.

Animals↗