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Biomedical subjects

D Wong

Publications and source records attributed to D Wong.

At least 181 records · Page 10Linked to original sources
PubMed1994

Mapping of a gene for autosomal dominant juvenile-onset open-angle glaucoma to chromosome Iq.

A large Caucasian family is presented, in which a juvenile-onset form of open-angle glaucoma is transmitted in an autosomal dominant fashion. Sixteen affected family members were identified from 31 at-risk individuals descended from the affected founder. Affected patients developed high intraocular pressures (sometimes > 40 mm Hg) within the first 2 decades of life. Linkage analysis between the disease phenotype and 12 microsatellite repeat markers located on chromosome 1q gave a maximum lod score of 8.38 at a recombination fraction of zero for marker D1S210. Analysis of recombinant haplotypes suggests a total inclusion region of about 14 cM between markers D1S194 and D1S218 at 1q21-q31. This represents the second juvenile-glaucoma family, in which the disease has been mapped to the long arm of chromosome 1.

Adolescent↗
PubMed1993

HIV-related skin disease.

Most patients with HIV infection will develop an HIV-related lesion of the skin or mucous membranes before their progression to AIDS. As the skin is readily observed by patients and easily examined by doctors, skin disease presents a good opportunity for the early diagnosis of HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Influence of haptic materials on the adherence of staphylococci to intraocular lenses.

A recent case-control study indicated that the insertion of an intraocular lens with polypropylene (Prolene) haptic materials was a significant risk factor for postoperative endophthalmitis (odds ratio = 4.5, P < .01). In the present study, we used quantitative techniques to evaluate adherence of Staphylococcus epidermidis to two intraocular lens types--lenses with polypropylene haptic materials and all-polymethyl methacrylate optic and three-piece all-polymethyl methacrylate lenses--using a quantitative culture method, a radioisotope technique, and scanning electron microscopy. All three methods demonstrated approximately twice as many bacteria adherent to lenses with polypropylene haptic materials as to all-polymethyl methacrylate lenses. Scanning electron microscopy showed preferential bacterial adherence to the polypropylene haptic materials. These data provide a pathogenic mechanism to explain our epidemiologic findings of an increased risk of postoperative endophthalmitis associated with implantation of intraocular lenses with polypropylene haptic materials.

Adsorption↗
PubMed1993

The influence of temporal pattern of stimulation on delay tuning of neurons in the auditory cortex of the FM bat, Myotis lucifugus.

In echolocating bats, delay-sensitive neurons show facilitative responses to simulated pulse-echo pairs at particular echo delays. Three experiments examined how the temporal pattern of stimulation affected the delay tuning of neurons in the auditory cortex of the awake FM bat, Myotis lucifugus. First, delay tuning was compared using a series of pulse-echo pairs fixed in echo delay ('standard' stimuli), and a series of pulse-echo pairs in which successive sound pairs decreased by a fixed echo-delay step ('approach' stimuli). Similar best delays were measured with both stimulation patterns presented at repetition rates in which the neuron was delay-sensitive. At the higher delay-sensitive pulse repetition rates, approach stimuli evoked larger delay-dependent responses. Second, approach stimuli were fixed at different intertrial intervals. The best delay was unaffected by intertrial interval, although some neurons showed larger responses for longer intertrial intervals (0.5, 1.0 s), especially at the higher delay-sensitive pulse repetition rates. Third, approach stimuli were fixed at different echo-delay steps to simulate target velocity. The majority of neurons showed some sensitivity to echo-delay step, with clear preference for target velocity mainly between 1.8-7.0 m/s. This suggests that delay-sensitive neurons compute target velocity by rate of change of echo delay over successive echoes. Thus, response properties of cortical neurons are influenced by dynamic acoustic conditions found in target-directed flight.

Acoustic Stimulation↗
PubMed1993

Pregnancy in women with end-stage renal disease: treatment of anemia and premature labor.

There is little experience with the use of various therapies in the end-stage renal disease patient who becomes pregnant. Erythropoietin for the treatment of anemia has become part of the standard treatment regimen of dialysis patients, but experience with its use in pregnancy is limited. We report five cases of its use in dialysis patients during pregnancy. We found no evidence that it crossed the placenta or that it made blood pressure control more difficult. We found that patients required a higher dose of erythropoietin to maintain hematocrit levels than they had before pregnancy. Another therapy involves the treatment for premature labor, which is the most common cause of pregnancy loss in dialysis patients. Two of our patients were successfully treated with indomethacin for premature labor. Both drugs are useful tools in the management of pregnant dialysis patients.

Abnormalities, Drug-Induced↗
PubMed1993

Altered patterns of drug metabolism in patients with acquired immunodeficiency syndrome.

Caffeine was used to assess acetylation status and indexes of oxidative drug metabolism (demethylation, xanthine oxidation, and 8-hydroxylation) in a control group and in three groups of patients infected with human immunodeficiency virus (HIV): patients with acquired immunodeficiency syndrome (AIDS) who had acute illnesses, stable patients with AIDS, and asymptomatic patients infected with HIV. The prevalence of apparent slow acetylation was greater in AIDS patients with acute illnesses compared with control subjects (27 of 29 [93%] versus 18 of 29 [62%]). Indexes of demethylation were decreased and 8-hydroxylation increased in these patients. Xanthine oxidation was the same as that in the control subjects. In the stable AIDS patients, oxidative pathways were altered in a manner similar to that observed in the AIDS patients with acute illnesses, but acetylation was the same as that in the control subjects. In HIV-infected asymptomatic patients, drug metabolism was the same as that in the control subjects. The increased prevalence of apparent slow acetylation and the altered activity of the oxidative pathways in AIDS patients with acute illnesses may partly explain the increased incidence of adverse drug reactions in these patients.

Acetylation↗
PubMed1993

Gemcitabine in advanced renal cell carcinoma. A phase II study of the National Cancer Institute of Canada Clinical Trials Group.

BACKGROUND: Gemcitabine (2', 2'-difluorodeoxycytidine; dFdC) an anticancer agent with activity in preclinical models, was felt to be a promising new chemotherapy drug which warranted testing in patients with advanced renal cell carcinoma. METHODS: Eighteen patients with histologically proven metastatic or locally recurrent renal cell carcinoma and bidimensionally measurable disease were accrued to a phase II study of gemcitabine administered intravenously on days 1, 8 and 15 of a 28 day treatment cycle. Initial doses of gemcitabine were 800 mg/m2; doses in subsequent cycles were escalated to a maximum of 1250 mg/m2, toxicity permitting. RESULTS: One partial response was seen for a response rate of 6%. Hematologic toxicity was not severe with this dosing schedule; however, two patients developed dyspnea with bronchospasm after repeated injections of drug. CONCLUSIONS: The dose and schedule of gemcitabine employed results in only a modest response rate in patients with advanced renal carcinoma. Investigators should be aware of the possibility of dyspnea and bronchospasm developing shortly after gemcitabine administration.

Adult↗
PubMed1993

Epidermal cytokines in murine lupus.

Murine lupus and the analogous human disease systemic lupus erythematosus (SLE) in humans are characterized by multisystem disease accompanied by the production of numerous serum autoantibodies. The classic model of murine lupus is the New Zealand black mouse (NZB). In this strain anti-DNA antibodies are the most specific marker for the presence of murine lupus, in that this autoantibody parallels both the development and activity of the disease. Exposure to ultraviolet (UV) radiation is known to exacerbate the disease in both the murine and the human disease. UV irradiation of the skin increases serum levels of certain cytokines including interleukin-1 (IL-1), IL-6, and granulocyte/macrophage-colony stimulating factor (GM-CSF), which can influence B- and T-cell function. Recent studies have focused on the role of cytokines in SLE. We hypothesize that the ultraviolet (UV)-induced exacerbation in NZB mice in part is mediated by UV-induced cytokines such as IL-1. Eight-week-old female NZB and DBA/2 mice were exposed to UV irradiation. Sera and supernatants from spleen cell cultures were assayed for anti-DNA antibodies. After UV exposure, NZB mice showed a marked increase in such antibodies. Skin from both strains of mice was probed for IL-1 alpha mRNA before and after UV irradiation. At 24 h, DBA/2 mice had a slight increase in mRNA coding for IL-1 alpha, whereas a much greater increase in skin IL-1 alpha was seen in the NZB skin. This increase in IL-1 mRNA was associated with similar increases in IL-1 bioactivity. These data suggest that the mechanism underlying the UV-induced exacerbation of lupus is mediated in part by the cutaneous production of IL-1.

Animals↗
PubMed1993

Hyperinsulinaemia in the polycystic ovary syndrome confirmed with a specific immunoradiometric assay for insulin.

OBJECTIVE: Hyperinsulinaemia in the polycystic ovary syndrome (PCOS) has previously been defined using polyclonal radioimmunoassays (RIA) in which partially processed insulin-like molecules cross-react. This study aimed to reassess hyperinsulinaemia in women with PCOS using specific immunoradiometric assays (IRMA) for insulin, proinsulin and 32-33 split proinsulin. DESIGN: Patients attended for 75 g oral glucose tolerance tests and were divided into groups depending on their degree of obesity and fasting insulin status determined by RIA. IRMA measurements for insulin-like molecules in plasma from patients with PCOS and controls were compared. PATIENTS: Thirty-four patients with ultrasound diagnosed PCOS presented to a reproductive endocrinology clinic. A control group comprised women with normal ovaries on ultrasound. Four groups were constructed, two with normal fasting insulin concentrations (lean PCOS and controls) and two with hyperinsulinaemia (lean and obese PCOS). MEASUREMENTS: Plasma glucose, insulin (RIA and IRMA), proinsulin and 32-33 split proinsulin concentrations were measured at time 0, 30 and 120 minutes of an oral glucose tolerance test. RESULTS: Hyperinsulinaemia determined by RIA in lean and obese women with PCOS was confirmed using a specific IRMA assay for insulin. Plasma proinsulin and 32-33 split proinsulin concentrations were higher in hyperinsulinaemic women with PCOS compared with women with normal insulin concentrations. The proportion of circulating insulin-like molecules represented by proinsulin and 32-33 split proinsulin was similar in all groups studied. CONCLUSIONS: Hyperinsulinaemia in PCOS is likely to reflect insulin resistance because the raised concentrations of proinsulin and 32-33 split proinsulin were in proportion to the raised insulin concentrations. Hyperinsulinaemia in PCOS, defined by RIA, therefore differs from that in non-insulin dependent diabetes mellitus where it is largely accounted for by disproportionate hyperproinsulinaemia.

Blood Glucose↗
PubMed1993

Analyzing the red-shift characteristics of azulenic, naphthyl, other ring-fused and retinyl pigment analogs of bacteriorhodopsin.

Prompted by the near infrared-absorbing properties of some of the azulenic bacteriorhodopsin (bR) analogs, we have analyzed their absorption characteristics along with 11 new related ring-fused analogs and the corresponding Schiff bases (SB) and protonated Schiff bases (PSB). The following three factors are believed to contribute to the total red shift of each of the pigment analogs (sigma RS): perturbation of the basic chromophore (SB shift, delta SB), protonation of the SB (PSB shift, PSBS) and protein perturbation (the opsin shift, OS). For each factor, effects of structural modifications were examined. For the red-shifted pigments, percent OS has been suggested as an alternate way of measuring protein perturbation. Computer-simulated chromophores provided evidence against any explanation involving altered shapes of the binding pocket as a major cause for absorption differences. Implications of the current bR results on preparation of further red-shifted bR and possible application to visual pigment analogs are discussed.

Absorption↗
PubMed1993

Pars plana vitrectomy for the treatment of rhegmatogenous retinal detachment uncomplicated by advanced proliferative vitreoretinopathy.

A consecutive series of 114 eyes (112 patients) undergoing pars plana vitrectomy for rhegmatogenous retinal detachment not complicated by severe proliferative vitreoretinopathy is presented (follow up 1 to 4 years; mean 19 months). The indications for vitrectomy fell into two main groups: (1) where the retinal view was poor and vitrectomy was required to clear media opacities to allow identification of retinal breaks (n = 62); and (2) where technically difficult breaks existed and vitrectomy with internal tamponade was used to relieve vitreoretinal traction and facilitate retinal break closure (n = 44). In some of these cases the need for scleral buckling was eliminated. A smaller third group (n = 8) existed where the position of the break(s) was uncertain in the presence of an adequate view. The success rate with one procedure was 74% and with further surgery retinal reattachment was achieved in 92%. At 6 months after further surgery, beyond which interval no new failures were encountered, best corrected visual acuity was improved in 92 eyes (81%), unchanged in 14(12%), and worse in eight (7%). We conclude that pars plana vitrectomy is an effective method for treatment of selected cases of rhegmatogenous retinal detachment not complicated by proliferative vitreoretinopathy.

Adolescent↗
PubMed1993

The formation and maintenance of the definitive endoderm lineage in the mouse: involvement of HNF3/forkhead proteins.

Little is known about genes that govern the development of the definitive endoderm in mammals; this germ layer gives rise to the intestinal epithelium and various other cell types, such as hepatocytes, derived from the gut. The discovery that the rat hepatocyte transcription factor HNF3 is similar to the Drosophila forkhead gene, which plays a critical role in gut development in the fly, led us to isolate genes containing the HNF3/forkhead (HFH) domain that are expressed in mouse endoderm development. We recovered mouse HNF3 beta from an embryo cDNA library and found that the gene is first expressed in the anterior portion of the primitive streak at the onset of gastrulation, in a region where definitive endoderm first arises. Its expression persists in axial structures derived from the mouse equivalent of Hensen's node, namely definitive endoderm and notochord, and in the ventral region of the developing neural tube. Expression of the highly related gene, HNF3 alpha, appears to initiate later than HNF3 beta and is first seen in midline endoderm cells. Expression subsequently appears in notochord, ventral neural tube, and gut endoderm in patterns similar to HNF3 beta. Microscale DNA binding assays show that HNF3 proteins are detectable in the midgut at 9.5 days p.c. At later stages HNF3 mRNAs and protein are expressed strongly in endoderm-derived tissues such as the liver. HNF3 is also the only known hepatocyte-enriched transcription factor present in a highly de-differentiated liver cell line that retains the capacity to redifferentiate to the hepatic phenotype. Taken together, these studies suggest that HNF3 alpha and HNF3 beta are involved in both the initiation and maintenance of the endodermal lineage. We also discovered a novel HFH-containing gene, HFH-E5.1, that is expressed transiently in posterior ectoderm and mesoderm at the primitive streak stage, and later predominantly in the neural tube. HFH-E5.1 is highly similar in structure and expression profile to the Drosophila HFH gene FD4, suggesting that HFH family members have different, evolutionarily conserved roles in development.

Amino Acid Sequence↗
PubMed1993

Disappearing bone disease of the upper extremity.

Disappearing bone disease (Gorham's disease) is a rare clinical problem. The extensive bone loss seen with this entity makes it a difficult therapeutic problem, especially if contiguous bones are involved, which is a highly unusual occurrence. We report a case of disappearing bone disease involving the upper extremity and review the relevant literature.

Female↗
PubMed1993

Eosinophils are the major source of transforming growth factor-beta 1 in nodular sclerosing Hodgkin's disease.

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional cytokine which promotes fibroblast growth and collagen synthesis, but suppresses growth and differentiation of immune lymphocytes and killer cells. Immunohistochemical detection of TGF-beta 1 in Hodgkin's disease (HD) has been shown to correlate with the histologic feature of nodular sclerosis, which is associated with a favorable prognosis (American Journal of Pathology 1990, 136:1209). In that study, TGF-beta 1 was localized mainly at the margins of broad collagen bands (presumably sites of new collagen synthesis) and in areas containing numerous Hodgkin/Reed-Sternberg cells (H/RS). In these areas, TGF-beta 1 protein was found on the membrane and occasionally within the cytoplasm of H/RS cells. To determine whether TGF-beta 1 is synthesized by H/RS cells or secondarily bound to their membrane and sometimes internalized, we performed in situ hybridization (ISH) using 1.5 Kb 35S-labeled anti-sense and sense RNA probes to TGF-beta 1. Paraffin-embedded tissues of 10 cases from all histologic types of HD were examined. Somewhat unexpectedly, the major site of TGF-beta 1 mRNA was in eosinophils; TGF-beta 1 mRNA was not detected in H/RS cells. TGF-beta 1 mRNA was found in eosinophils in all cases of nodular sclerosis but not in other types of HD, despite the presence of numerous eosinophils in mixed cellularity cases. The presence of TGF-beta 1 mRNA coincided with immunohistochemical detection of TGF-beta 1 protein using antibody CC (1-30). These results confirm the role of TGF-beta 1 in the histogenesis of nodular sclerosing HD and indicate that eosinophils are the major source of TGF-beta 1 in this type of HD.

Adult↗
PubMed1992

Low temperature-induced fatty acid desaturation in Brassica napus: thermal deactivation and reactivation of the process.

When Brassica napus plants are grown at low temperatures (e.g., 5 degrees C) the rate of desaturation in leaves of newly formed fatty acids in both chloroplastic (MGDG) and cytosolic (PC) diacylglycerols is higher or more rapid than in plants grown at higher temperatures (e.g., 30 degrees C). This low temperature-induced increase in the rate of desaturation is lost within hours if plants are transferred to higher temperatures. However, if plants are then returned to low temperatures they regain the ability to rapidly desaturate fatty acids. This process is restored relatively slowly (over days) in contrast to the more rapid loss at high temperatures. This has important physiological consequences on the level of unsaturated fatty acids in plant membranes and the process of temperature control of the fatty acid composition of membrane lipids.

Brassica↗
PubMed1992

The treatment of bullous rhegmatogenous retinal detachment.

We describe the results of a consecutive series of 97 cases of bullous superior retinal detachment treated by conventional surgery. The retinal detachments were characterized by either a single retinal break or multiple retinal breaks confined within 1 clock hour and no proliferative vitreoretinopathy. The surgery involved sequential drainage of subretinal fluid, injection of air, cryotherapy and the application of local explant. All cases would otherwise be suitable for pneumatic retinopexy. The anatomical success rate was 85.5% with a single operation and 97% with further procedures. We report on the complications encountered and appraise the advantages and disadvantages of this operation. Forty-five of the 97 cases had detachment of the macula for less than 2 weeks, and 35 of the 45 (80%) achieved a visual acuity of 6/18 or better. These visual results challenge the assertion that better visual outcome might be attained with pneumatic retinopexy.

Air↗