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Biomedical subjects

J P Ng

Publications and source records attributed to J P Ng.

At least 19 recordsLinked to original sources
PubMed2006

Best practice in primary care pathology: review 8.

This eighth best practice review examines four series of common primary care questions in laboratory medicine: (i) sodium abnormalities; (ii) faecal occult blood testing; (iii) warfarin management; and (iv) sputum cytology in diagnosis of bronchopulmonary malignancy. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Anticoagulants↗
PubMed2005

Falsely high glycated haemoglobin [HbA1C] because of haemoglobin OSU-Christiansborg.

Glycated haemoglobin (HbA1c) is routinely used to assess the degree of glycaemic control in diabetic patients. We report a case of a 73 year old diabetic woman who had an elevated HbA1c of 13.4%. She was on maximum oral hypoglycaemic agents and was commenced on insulin. However, her HbA1c continued to remain high at 20.4%. Subsequent tests revealed that she had a haemoglobin variant, Haemoglobin Osu-Christiansborg, causing the falsely high glycated haemoglobin.

Aged↗
PubMed2000

Fatal cold anti-i autoimmune haemolytic anaemia complicating hairy cell leukaemia.

Hairy cell leukaemia (HCL) is a rare lymphoproliferative disorder associated with pancytopenia, splenomegaly and the presence of typical hairy B lymphocytes in the bone marrow and/or peripheral blood. The most significant complication relates to opportunistic infections that arise as a consequence of neutropenia and monocytopenia. HCL is occasionally associated with systemic autoimmune disorders including polyarteritis nodosa and rheumatoid disease. Secondary autoimmune haemolytic anaemia (AIHA) appears to be rare. We report on two cases of HCL complicated by fatal cold anti-i AIHA. Fulminant haemolysis causing death is rare in cold AIHA and only a few individual cases have been reported, none having anti-i specificity.

Aged↗
PubMed1996

Efficacy of recombinant interferon-alpha (rIFN-alpha) in polycythaemia vera: a study of 17 patients and an analysis of published data.

The efficacy and tolerability of rIFN-alpha has been evaluated in 17 selected patients with symptomatic polycythaemia vera, diagnosed according to the PRV Study Group criteria. Complete disease control (CR) was achieved, after 1-12 months, in nine patients, with partial control in a further five cases. Three patients failed to respond. Pruritus significantly improved in 83% (10/12) of cases, following 1-28 weeks of treatment. Six patients (35%), however, were unable to tolerate rIFN-alpha, on account of weight loss, myalgia and mental changes. Overall, alpha-interferon therapy significantly improved venesection requirements, MCV and PCV values, platelet counts, pruritus scores and the degree of splenomegaly. Analysis of pooled published data (100 evaluable patients, including the present study) revealed an overall CR of 60%, a PR of 27%, and a failure rate of 13%. Significant pruritus control (> 50% improvement) occurred in 77% of cases. rIFN-alpha appears to be an effective therapy for PV-associated myeloproliferation and/or pruritus, although side-effects remain a concern. Long-term studies are now indicated to determine if the natural history of the disease is altered, in particular whether the incidence of myelofibrosis and/or leukaemic transformation is reduced.

Adult↗
PubMed1996

Acute and repeated systemic amphetamine administration: effects on extracellular glutamate, aspartate, and serine levels in rat ventral tegmental area and nucleus accumbens.

Recent work indicates an important role for excitatory amino acids in behavioral sensitization to amphetamine. We therefore examined, using in vivo microdialysis in awake rats, the effects of amphetamine on efflux of glutamate, aspartate, and serine in the ventral tegmental area and nucleus accumbens, brain regions important for the initiation and expression of amphetamine sensitization, respectively. Water-pretreated and amphetamine-pretreated rats were compared to determine if sensitization altered such effects. In both brain regions, Ca2+-dependent efflux of glutamate accounted for approximately 20% of basal glutamate efflux. A challenge injection of water or 2.5 mg/kg of amphetamine did not significantly alter glutamate, aspartate, or serine efflux in the ventral tegmental area or nucleus accumbens of water- or amphetamine-pretreated rats. However, 5 mg/kg of amphetamine produced a gradual increase in glutamate efflux in both regions that did not reverse, was observed in both water- and amphetamine-pretreated rats, and was prevented by haloperidol. Although increased glutamate efflux occurred with too great a delay to mediate acute behavioral responses to amphetamine, it is possible that repeated augmentation of glutamate efflux during repeated amphetamine administration results in compensatory changes in levels of excitatory amino acid receptors in the ventral tegmental area and nucleus accumbens that contribute to development of expression of amphetamine sensitization.

Amino Acids↗
PubMed1992

Anomalous effect of mazindol on dopamine uptake as measured by in vivo voltammetry and microdialysis.

The effect of mazindol on the dopamine (DA) uptake system in the rat striatum was studied by in vivo voltammetry and microdialysis. An increase in the maximal uptake rate was observed by voltammetry 30 min after i.p. administration of 1, 5, 10, 15, and 20 mg/kg doses but not after a dose of 25 mg/kg, while stimulated release was enhanced at all doses. The increased maximal uptake is in contrast to increased levels of extracellular DA observed with microdialysis following mazindol administration. This divergence of action is anomalous in the context of current understanding of the DA uptake system.

Animals↗
PubMed1991

Increased stimulated release and uptake of dopamine in nucleus accumbens after repeated cocaine administration as measured by in vivo voltammetry.

Electrically stimulated dopamine (DA) release (overflow) and uptake were measured with in vivo voltammetry in the nucleus accumbens (N ACC) of anesthetized rats that had previously received repeated cocaine treatments. Electrically stimulated DA release was induced by a 10-s stimulation in the medial forebrain bundle (2-ms, 200-microA, biphasic pulses at 100 Hz). DA overflow and uptake were measured with fast chronoamperometry using a Nafion-plated, carbon fiber electrode. Animals given repeated doses of cocaine (10 mg/kg s.c. from day 1 to 5, 20 mg/kg s.c. from day 6 to 10) showed marked increases in DA uptake (5.47 +/- 0.28 vs. 2.93 +/- 0.26 microM/s) and in stimulated DA overflow (27.3 +/- 1.1 vs. 18.9 +/- 1.3 microM) compared with DA uptake and stimulated overflow in saline control animals. The increased uptake was shown to be independent of the increased overflow. Uptake was monitored as a function of stimulation current, and the data were extrapolated to zero stimulation, resulting in calculated rates of uptake of 2.43 and 3.71 microM/s in the control and cocaine-treated groups, respectively. These effects were found to be temporary, as there were no significant differences in stimulated release or uptake between saline control animals and animals given 10 days of cocaine followed by a 10-day abstinence period. These alterations in the N ACC produced by repeated cocaine administration may be a compensatory response to prolonged uptake blockade of synaptic DA.

Animals↗
PubMed1990

Effect of chronic cocaine on dopamine synthesis in the nucleus accumbens as determined by microdialysis perfusion with NSD-1015.

Reduced steady state formation of dihydroxyphenylalanine (DOPA) (47%) was found in the nucleus accumbens (N. ACC) of rats treated with ten days of repeated cocaine (10 mg/kg, i.p.) as compared to saline controls after NSD 1015 perfusion (10(-4) M) by microdialysis. In addition, prior to NSD 1015 perfusion, basal extracellular levels of the dopamine metabolite, dihydroxyphenylacetic acid (DOPAC) in the N. ACC were 33% lower in the chronic cocaine-treated animals. The results indicate the rate of dopamine synthesis in the N. ACC is significantly reduced by repeated cocaine administration.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Coexpression of cytokeratin and vimentin.

The reported incidence of cytokeratin and vimentin intermediate filament coexpression is rapidly expanding. An up-do-date list of the instances in which this occurs is presented and the implications of this event are discussed.

Adult↗