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Biomedical subjects

A Hong

Publications and source records attributed to A Hong.

11 recordsLinked to original sources
PubMed1992

Inhibition of a dihydropyridine, omega-conotoxin insensitive Ca2+ channel in rat synaptosomes by venom of the spider Hololena curta.

Inhibition of the N and L type Ca2+ channels with omega conotoxin GVIA (omega-CgTx) together with the dihydropyridine (-)-202-791 produces slight reduction (congruent to 25%) of K(+)-evoked Ca2+ influx in mammalian synaptosomes. These results and others suggest the existence of a third high threshold voltage sensitive calcium channel (VSCC) responsible for the majority of influx. Venom from the funnel web spider Hololena curta potently and persistently inhibited Ca2+ influx in rat cortical synaptosomes (IC50 1:10,000 or 4.21 micrograms/venom protein/ml of synaptosomes). Also Ca2+ influx in cerebellar synaptosomes was inhibited in a similar manner. K(+)-evoked tritium release from synaptosomes labeled with [3H]noradrenaline was inhibited by Hololena venom (congruent to 60% reduction at 10 micrograms/venom protein). Inhibition of Ca2+ influx by venom was unaffected by combined omega-CgTx and (-)-202-791 pretreatment (both 1 microM). Hololena venom and its active constituent should provide useful tools to investigate the role of this novel Ca2+ channel in neuronal function.

Animals↗
PubMed1992

Pseudomembranous colitis in sickle cell disease responding to exchange transfusion.

We report a case of ischemic colitis with pseudomembrane formation in a 6 1/2-year-old boy with sickle cell disease that responded to medical management including exchange transfusion. This case was not associated with Clostridium difficile infection but with an elevation of serum levels of tumor necrosis factor alpha. This rare complication of sickle cell disease has been reported only in adults.

Abdominal Pain↗
PubMed1991

Laparoscopic cholecystectomy: a treatment option for gallbladder disease in children.

Laparoscopic cholecystectomy was performed safely in two children ages 7 and 15 years. Special considerations were required in the younger child because of the discrepancy between the length of the instruments and the size of the peritoneal cavity. Both children remained in hospital less than 24 hours and were able to resume normal diet and activity quickly. Pediatric surgeons with special training in laparoscopic surgery may want to use this treatment modality for children with biliary tract disease.

Adolescent↗
PubMed1991

Lung function and radiation response.

This study investigated whether impaired respiratory function affected the response to radiotherapy. A prospective study was performed in which lung function, arterial oxygen and haemoglobin concentration were examined, before treatment with radical radiotherapy, in 141 patients with advanced non-small cell lung cancer and head and neck cancer. The findings were considered to reflect the physiological conditions present at the time of radiotherapy and these were related to acute normal tissue reactions and tumour control. Although 53% of the patients showed some impairment of lung function and 47% demonstrated a haemoglobin oxygen saturation below the normal range, oxygen partial pressure was below expected levels in fewer patients (27%) and total arterial oxygen content was below normal in only 12% of patients. No correlation was found between the tests performed and the severity of acute morbidity or with local tumour control. In the patients with carcinoma of the bronchus, there was a trend for incomplete tumour control to be associated with a lower haemoglobin level, but this did not reach statistical significance. In patients selected for curative radiotherapy, lung function would not appear to be an important factor influencing the response of normal tissues or tumour to irradiation.

Adult↗
PubMed1990

An audit of head and neck cancer treatment in a Regional Centre for Radiotherapy and Oncology.

All patients with head and neck cancer attending the Regional Centre for Radiotherapy and Oncology at Mount Vernon hospital during the 8-year period from 1 January 1980 to 31 December 1987 have been included in this review. The 545 patients presenting a new primary carcinoma without evidence for metastasis outside the locoregional area, who were treated primarily by radiotherapy are the subject of this present audit. The characteristics of the patients, of the tumours and of the treatment given have been related to outcome. Early tumours (T1 and T2 which were node-negative) showed a complete response (CR) rate of 94% whereas more advanced tumours (T1 and T2 with palpable lymph nodes) showed a CR of 59%. The probability of local tumour control at 5 years was 77% in those without nodes and 20% in those with nodes. For more advanced disease (T3 and T4 tumours), initial CR was 72% in node-negative disease and 32% when the nodes were positive. At 5 years, the probability of local tumour control fell to 37% and 0 respectively. CR, freedom from recurrence and survival were statistically significantly related to T stage, N stage and site of primary tumour. The results compare favourably with those reported by other institutions. The development of medical audit and its influence on treatment policy are considered.

Adolescent↗
PubMed1990

Pituitary surgery--a report of 46 cases.

Resection of pituitary adenomas, by the transcranial, or more commonly, by the transsphenoidal approach is an established operation in Singapore. The authors review the results of pituitary surgery in 46 patients over a 7 year period. Forty patients had transsphenoidal surgery. Six patients had transcranial resection of their tumours. There was only one operative mortality and low morbidity. Total macroscopic resection was achieved in all but 7 patients. Eighteen of 21 patients with non-secretory adenomas had radiological evidence of cure. Normalisation of growth hormone levels was achieved in 6 out of 9 acromegalics. Three out of 6 patients with Cushing's disease had normal ACTH following surgery. Only 1 out of 6 patients was cured of her prolactinoma. Vision improved in 16 out of 25 patients with decreased vision preoperatively.

Adenoma↗
PubMed1989

Monospecific antibodies against a synthetic peptide predicted from the alpha-3 nicotinic receptor cDNA inhibit binding of [3H]nicotine to rat brain nicotinic cholinergic receptor.

Polyclonal antibodies were raised against a synthetic decapeptide (designated S3) predicted from a segment of the alpha-3 subunit cDNA (amino acid residues 130-139) encoding the rat brain nicotinic cholinergic receptor. This segment was selected because it may be proximate to the nicotine/acetylcholine-binding site of the receptor (1). By radioligand binding assays and sucrose density gradient centrifugation, these monospecific antibodies were shown to inhibit the binding of [3H]nicotine to both the large molecular weight rat brain receptor (240 kDa) and to an SDS-disaggregated nicotine-binding subunit species (80 kDa), in a dose-dependent manner. The neutralizing effect of the anti-S3 antibodies supports the view that this region of the protein is closely related to the agonist binding site.

Amino Acid Sequence↗
PubMed1989

Continuous hyperfractionated accelerated radiotherapy in locally advanced carcinoma of the head and neck region.

Shortening of the overall duration of radiotherapy would reduce the possibility repopulation of tumor during treatment. Most clinical trials of such accelerated radiotherapy have incorporated a split course to improve normal tissue tolerance. Any interruption, however, even for the week-end, may allow repopulation to occur. A scheme of radiotherapy has been used during which treatment was given 3 times per day on each of 12 consecutive days without interruption for the week-end. In a pilot study a significant improvement in survival and local tumor control has been achieved in 48 patients with head and neck tumors when comparison was made with a previously treated group. A randomized controlled clinical trial is planned.

Adult↗
PubMed1989

Normobaric oxygen as a sensitizer of hypoxic tumor cells.

A series of experiments have been performed to determine the relative radiosensitivities of a mouse mammary tumor (CA NT) irradiated in 100% normobaric oxygen or in air, using clinically relevant dose-fractionation schedules. The results demonstrate that normobaric oxygen is a potent radiosensitizer, its effect being more marked with smaller size fractions. Enhancement ratios (ER) of 1.23 to 1.45 were obtained. By contrast, no significant benefit was seen with single doses (ER = 1.05 +/- 0.14). The degree of radiosensitization with oxygen, in these fractionated regimens, is greater than that reported for the chemical radiosensitizer, misonidazole. It therefore seems appropriate to re-examine the clinical potential of normobaric oxygen and to consider how the conditions of normobaric radiotherapy achieved in the laboratory can be translated to man.

Adenocarcinoma↗