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Biomedical subjects

D Chong

Publications and source records attributed to D Chong.

14 recordsLinked to original sources
PubMed2005

Accuracy of thin section magnetic resonance using phased-array pelvic coil in predicting the T-staging of rectal cancer.

Magnetic resonance (MR) imaging may contribute to staging rectal cancer and inform the decision regarding administration of pre-operative radiotherapy. The accuracy of MR has been debated. The aim of the present study was to determine the accuracy of thin section T2-weighted MR images in rectal cancer patients. MR results were compared with histological assessment of resection specimens. Over a 2-year period, 42 patients were studied. Histological staging was pT2 n = 13, pT3 n = 25 and pT4 n = 4. MR diagnostic accuracy was 74%. MR sensitivity and specificity was 62% and 79% for pT2 lesions, 84% and 59% for pT3 lesions and 50% and 76% for pT4 lesions. Estimation of tumour penetration by thin section MR imaging of rectal cancers using pelvic phased-array coil has moderate diagnostic accuracy. The limitations of MR should be acknowledged when selecting rectal cancer patients for pre-operative radiotherapy.

Adenocarcinoma↗
PubMed2001

The extended trochanteric osteotomy in revision hip arthroplasty: a critical review of 166 cases at mean 3-year, 9-month follow-up.

We conducted a retrospective review of 192 consecutive revision hip arthroplasties with an extended proximal femoral osteotomy performed from 1992 through January 1998. Of these osteotomies, 166 had a minimum of 2 years of clinical and radiographic follow-up (range, 2-7.5 years; average, 3 years, 9 months). All patients had a femoral reconstruction with an extended trochanteric osteotomy and an extensively porous-coated, cementless femoral component. The average age at revision was 65.8 years (range, 26-84 years). Of the 166 osteotomies, 2 nonunions (1.2%) and 1 malunion (0.6%) were identified. Seventeen hips (10.2%) required reoperation. Pain and walking scores improved from a mean of 6.5 preoperatively to 9.8 postoperatively. The extended trochanteric osteotomy heals predictably and enhances the surgeons' ability to address many difficult issues encountered in revision arthroplasty.

Adult↗
PubMed2000

Choice of breastfeeding and physicians' advice: a cohort study of women receiving propylthiouracil.

OBJECTIVE: To examine the gap between the current social/medical practice and the evidence-based recommendation in favor of breastfeeding during maternal propylthiouracil (PTU) therapy. DESIGN: Prospective, observational, cohort study. SUBJECTS: Women requiring PTU during pregnancy, and endocrinologists and family physicians in Ontario, Canada. INTERVENTIONS: Questionnaire. MAIN OUTCOME MEASURES: Women were interviewed postpartum regarding their choice of infant feeding method and relevant advice received from physicians. Physicians were questioned about their advice to nursing women receiving PTU. RESULTS: Of 78 women, 66 had live births. Thirty-six required PTU postpartum (group 1), and 30 did not (group 2). Thirty-six healthy women served as controls (group 3). Breastfeeding initiation rates for groups 1, 2, and 3 were 44%, 83%, and 83%, respectively. In group 1, 15 women who breastfed received advice from 22 physicians regarding breastfeeding (20 in favor, 1 against, and 1 equivocal). Eleven who formula fed received advice from 17 physicians (4 in favor, 12 against, and 1 equivocal). A logistic regression analysis of group 1 showed that physicians' advice was the only significant predictor of the woman's choice to breastfeed during PTU therapy (relative risk: 5.48; 95% confidence interval: 1.28-23.40). The physician survey showed that 44% of endocrinologists do not recommend breastfeeding during PTU therapy. CONCLUSIONS: A substantial proportion of the lactating patients on PTU still receive advice against breastfeeding from their physicians. Physicians' advice and attitudes toward breastfeeding during PTU therapy are a major factor in women's final decision to breastfeed. Physicians' compliance with evidence-based data will facilitate breastfeeding in this group.propylthiouracil, breastfeeding, decision-making.

Attitude of Health Personnel↗
PubMed2000

Birth outcome in incarcerated, high-risk pregnant women.

OBJECTIVE: To compare birth outcomes in incarcerated women with a recent history of drug use to those of nonincarcerated women in a methadone maintenance program. STUDY DESIGN: We retrospectively analyzed pregnancy outcome in 149 women who delivered at full term between 1993 and 1996. Thirty-one patients incarcerated during pregnancy (group 1) were compared with 47 patients enrolled in our methadone maintenance program (group 2) and with a control group of 71 randomly chosen patients (group 3). Drug use, age, parity, number of visits, infant birth weight, low birth weight and Apgar scores were compared. RESULTS: The methadone maintenance group had significantly fewer clinic visits. All the patients in groups 1 and 2 were cigarette smokers, whereas 12.5% of the control group smoked. Over 78% of incarcerated women admitted using drugs immediately prior to imprisonment as compared to 4.11% in group 3 and 100% in group 2 (P < .001). The three groups differed significantly with respect to infant birth weight (P < .001). CONCLUSION: Cessation of drug use followed by adoption of a health-promoting lifestyle and adequate prenatal care of incarcerated women leads to an improvement in birth outcome. Furthermore, provision of prenatal care on site is a suitable alternative for the care of incarcerated pregnant women and eliminates the need to bring patients in chains to outside clinics.

Adult↗
PubMed1999

Adenoviral-mediated gene transfer of interleukin-6 in rat lung enhances antiviral immunoglobulin A and G responses in distinct tissue compartments.

The effect of IL-6 transgene expression following lung gene transfer on anti-adenovirus humoral responses of immunoglobulin (Ig) G and A both in the lung and peripheral blood was investigated. Lung infection by a control adenovirus caused an increased level of circulating anti-adenoviral IgG antibodies. However, the magnitude of this response was many times higher in the peripheral blood of rats receiving an adenovirus engineered to express IL-6 transgene. In comparison, much lower levels of anti-adenoviral IgG were detected in the bronchoalveolar fluids of rats receiving either virus. In contrast, there was no detectable level of anti-adenoviral IgA in the peripheral blood in any cases, yet significantly detectable levels of anti-adenoviral IgA were measured in the lung. The levels of this IgA were much higher in the lung of rats expressing IL-6 than in the lung of control animals (15 times higher by day 14). Our findings thus provide evidence that IL-6 plays a significant role in enhancing specific airways mucosal IgA and systemic IgG responses during local lung viral infection, and provide the rationale for using IL-6 locally at mucosa sites as an immune adjuvant for antiviral vaccination program.

Adenoviridae↗
PubMed1999

Antitumor effect of vaccinia virus in glioma model.

The ability of certain viruses to lyse cancer cells suggests that they may have potential as oncolytic agents. We investigated the effect of vaccinia virus (VV) and its recombinant derivatives (recVV2, rVV-p53) on growth of C6 rat glioma cells that form fast growing tumors in athymic nude mice. VV effectively infected C6 cells in vitro, inducing high level of foreign gene expression. Most of C6 cells infected in vitro with rVV-p53 expressing the tumor suppressor p53 protein showed apoptosis specific morphological changes in DAPI-stained nuclei and DNA fragmentation pattern on gel electrophoresis; infection with VV induced low level of cell apoptosis. In an ex vivo experiment, VV-infected C6 cells were implanted s.c. in athymic nude mice and tumor development was monitored. In contrast to the control PBS group, most of mice implanted with infected cells remained tumor free until the end of the observation period. In an in vivo experiment, injection of VV or rVV-p53 after the C6 cells had been implanted in nude mice induced effective inhibition of tumor growth in comparison with control PBS groups. The oncolytic effect was greater with rVV-p53, apparently due to overexpressed p53 and p53-mediated cell apoptosis. In study of virus virulence we did not observe disease symptoms in athymic mice infected with a high dose of VV. Experimental results indicate that vaccinia virus itself and vaccinia-mediated delivery of therapeutic genes represent novel potential strategies for tumor therapy.

Animals↗
PubMed1995

The relationship between glycine and gephyrin in synapses of the rat spinal cord.

In order to examine the relationship between gephyrin (the peripheral membrane protein associated with glycine receptors) and glycinergic boutons, we have carried out a post-embedding immunogold study of glycine-like immunoreactivity on sections of rat lumbar spinal cord which had previously been reacted with monoclonal antibody to gephyrin. In all three areas examined (laminae I and II, lamina III and lamina IX) the majority of profiles which were presynaptic at gephyrin-immunoreactive synapses were enriched with glycine-like immunoreactivity. It was estimated that at least 83% of profiles presynaptic to gephyrin-immunoreactive synapses in the superficial dorsal horn (laminae I and II) were glycine-immunoreactive, while for lamina III and the ventral horn (lamina IX) the proportions were at least 91% and 98% respectively. This provides strong evidence that glycine is a transmitter at those synapses where gephyrin- and glycine-like immunoreactivities are both present, but suggests that gephyrin may sometimes be expressed at non-glycinergic synapses and indicates the need for caution in using gephyrin-immunoreactivity as a marker for glycinergic synapses within the spinal cord. By reacting serial sections of dorsal horn with antisera to glycine and GABA, we have shown that many boutons in laminae I-III of the dorsal horn show both types of immunoreactivity and are therefore likely to use both amino acids as inhibitory transmitters. Many of the boutons which were presynaptic at axoaxonic synapses in the ventral part of lamina II and in lamina III were glycine- and GABA-immunoreactive and in many cases the postsynaptic element was the central axon of a type II synaptic glomerulus. Taken together with pharmacological evidence, this suggests that inhibitory interneurons in the dorsal horn which use both GABA and glycine may be important in controlling the flow of information from hair follicle afferents to other spinal neurons.

Afferent Pathways↗
PubMed1994

Serum potassium concentrations in trauma patients.

Hypokalemia occurs in 50% to 68% of trauma patients. To investigate the pathophysiology of these changes in serum potassium, we prospectively studied 133 trauma patients. Among the patients who had hypokalemia, the serum potassium usually decreased within 1 hour of trauma and returned to normal within 24 hours without significant potassium replacement. In bivariant analysis, age, admission systolic blood pressure, cardiac injury, and serum epinephrine level were associated with admission serum potassium value (K1), whereas sex, mechanism of injury, number of organ systems injured, blood glucose, serum alcohol, arterial pH, Injury Severity Score, trauma score, estimated blood loss, and urine potassium were not significantly related to K1. But in a multiple regression model, the only significant independent variables were age, arterial pH, and serum epinephrine level.

Adult↗
PubMed1989

Polycarbonate membranes: a novel surface for solid-phase determinations with utility in field format serological assays.

A dipstick suitable for immunoassay procedures has been developed, and its utility demonstrated by the development of tests for the determination of immunoglobulin levels in newborn bovine blood, and for the detection of bovine antibodies against Brucella abortus. The dipstick is of simple design, consisting of three components: a polycarbonate membrane, an adhesive, and a support material. The polycarbonate membrane is a porous filter material upon which the immunoassay is undertaken. Biomolecules bind to the membrane with sufficient affinity to permit the development of useful immunoassay procedures; however, this membrane exhibits low non-specific binding of reagents. Collectively, these properties make polycarbonate a useful material for solid-phase immunoassay procedures.

Animals↗
PubMedDate not supplied

Attentional processing in hyperthyroid children before and after treatment.

To determine whether specific components of attentional processing may be differentially disrupted during thyrotoxicosis, nine children with hyperthyroidism were assessed for intelligence and attention before and after one year of therapy. The attention test allowed for measurement of sustain, disengage, and shift subcomponents of attentional processing. Comparison with pediatric controls revealed lower nonverbal intelligence during thyrotoxicosis, which improved to normal following euthyroidism. On the attention task, an effect was observed during thyrotoxicosis only on the shift and disengage functions of attentional processing but not sustain. Attention results were unrelated to self-reported anxiety at time of testing. Results are discussed in terms of thyroid hormone activation of the prefrontal cortex, which is thought to be the cerebral substrate underlying the shift and disengage functions of attentional processing.

Anxiety↗