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Biomedical subjects

D Choy

Publications and source records attributed to D Choy.

At least 91 records · Page 5Linked to original sources
PubMed1988

Brainstem auditory evoked potentials after irradiation of nasopharyngeal carcinoma--report on two cases with myelopathy of the brainstem.

Brainstem auditory evoked potentials (BAEP) were recorded in two patients with nasopharyngeal carcinoma (NPC) irradiated 14 and three years ago respectively and compared with 15 healthy controls. The patients had features of post-irradiation myelopathy of the brainstem with reduced gag reflex, unilateral vocal cord paralysis and fasciculation of the tongue. The first patient had a blind left eye. The second patient had quadriparesis. All ears revealed post-irradiation otitis media changes and mixed deafness. BAEP was not recognizable in the left ear of the first patient and was normal in the left ear of the second patient. Simultaneous electrocochleogram and BAEP were recorded from the right ear of the first case. The wave I-V latency interval were prolonged in both right ears. In the absence of local recurrence and brain secondaries, these BAEP changes are attributed to the post-irradiation myelopathy of brainstem.

Brain Stem↗
PubMed1987

Evaluation of monoclonal antibodies for the detection of exfoliative nasopharyngeal carcinoma cells.

Exfoliative cells were aspirated from 15 patients suspected of having nasopharyngeal carcinoma (NPC) and showing the presence of lesions or other abnormalities in the nasopharynx. They were tested for binding with a 125I monoclonal antibody (MAb) (MA6) which is selectively reactive against human B lymphocytes and a variety of carcinomas. A positive result was obtained from 6/9 patients with, and from 0/5 patients without, histologically confirmed disease. One patient with eskimoma also gave a negative binding result. Cytology was specific but less sensitive, tumour cells being detected in 3 of the patients with confirmed disease. Immunocytology using MA6 was limited, like cytology, by poor recovery of the tumour cells and the results were in complete concordance with cytology. The other MAbs used were raised against carcinoembryonic antigen (CEA) and a carcinoma cell line (Ca2), respectively. The latter was not reactive against the NPC tumour cells while the CEA antibody was not sufficiently selective to be useful.

Adult↗
PubMed1987

Characterization of a murine monoclonal-antibody-defined B-lymphocyte carcinoma cross-reacting antigen (BLCa) from nasopharyngeal carcinoma tissues.

Biopsies were obtained from 12 patients suspected of having nasopharyngeal carcinoma (NPC). A portion of the tissue was submitted for histopathology and another for Western blotting using a murine monoclonal antibody (MAb), MA6. Touch smears of the tissues were also prepared immediately prior to extraction and Western blotting for immunoenzymic staining. The results showed that a B-lymphocyte carcinoma cross-reacting antigen (BLCa), or an antigen similar to it, was the major antigen in the tumor tissue recognized by MA6. The antigen was detected in tissues from 8 patients, of whom 7 had confirmed NPC and one had eskimoma, but not in tissue from the remaining 4 patients who did not have histologically confirmed malignancy. Immunocytology showed that tumour cells were present in the touch smears from all but one of the tumour patients but not in the other patients, and that the tumour cells comprised the large majority of the MA6-reactive cell population. The other MA6-reactive cell types present included certain weakly reactive epithelial cells and occasional lymphoid cells, presumably B lymphocytes. However, these cell types were similarly distributed between the tissues obtained from patients with or without malignant diseases. It was concluded, therefore, that the tumour cells in these tissues are the principal source of BLCa and, as such, the antigen may constitute an objective and reliable marker of NPC.

Animals↗
PubMed1987

Adjunctive chemotherapy to radical radiation therapy in the treatment of advanced nasopharyngeal carcinoma.

Sixty-eight consecutive patients with previously untreated nasopharyngeal carcinoma (NPC) with advanced cervical lymph nodal metastases were studied retrospectively for the effectiveness of combining chemotherapy with radical radiation therapy (RT). In 1981 and 1982, 36 patients were treated with radical radiation therapy alone (arm 1). In 1983, 13 patients were given 2 courses of VBMF prior to RT (arm 2). In 1984, 19 patients were given radical RT sandwiched between 2 courses of PVBMF before and 2 after (arm 3). The three arms were comparable in patient characteristics with similar stages of the disease, sex, age distribution, and rates of completion of the prescribed treatments. There was no significant difference in actuarial or disease-free survival between arm 1 and 3 or arm 2 and 3, but arm 1 compared favorably with arm 2 in actuarial survival (X2 = 9.533, p = 0.002). The distant relapses in arms 2 and 3 occurred at significantly shorter times after diagnosis than those in arm 1 (t = 4.1083, p = 0.0001). Postponement of radiation therapy by chemotherapy might have accounted for the earlier distant relapses in arm 2 and 3. Radiation therapy alone given in radical dose had been demonstrated to achieve significantly more complete responses in cervical nodal metastases than either forms of chemotherapy (VBMF or PVBMF) given just two courses prior to radiation therapy (p less than 0.00003). More controlled clinical trials must be completed before acceptance of chemotherapy as part of a standard radical treatment for advanced nasopharyngeal carcinoma with advanced cervical lymph nodal metastases. In all future trials, closer integration in time sequence between the two treatment modalities is indicated. Meanwhile cervical nodal status (CR vs, PR plus NR) at the end of any treatment was shown to be of paramount prognostic significance.

Actuarial Analysis↗
PubMed1985

Role of radionuclide imaging in the diagnosis of chondrosarcoma.

The diagnosis of chondrosarcoma may be difficult if there is an atypical radiographic appearance or an inconclusive biopsy. Radionuclide bone scans of 13 patients with chondrosarcoma were reviewed to assess if a pattern of scan features could be recognised in association with this tumour. A combination, including increased blood pool activity, moderate intensity of uptake, patchy uptake with cortical predominance of activity, minimal distortion of bony outline, and a well-defined scintigraphic margin, occurred regularly in the series. Recognition of this characteristic pattern of scintigraphic features in cases of suspected chondrosarcoma may assist in the diagnostic assessment.

Adolescent↗
PubMed1985

[Disobliteration of coronary arteries by the laser. Peroperative experience].

The authors report their experience of coronary artery disobliteration by laser in 10 patients. This was a preliminary study to assess the effects of an Argon laser on atheromatous coronary stenosis in vivo. This technique was used during coronary bypass surgery. Two series of patients were treated: an initial group of 5 patients who underwent laser therapy associated with coronary bypass surgery; a second group undergoing laser therapy alone without distal bypass grafting. The results were assessed by immediate angiography in the first series and by the passage of calibrated probes in both series. Secondary control angiography after 3 weeks was carried out in all patients. The immediate results showed a constant improvement (less than 25%) in the degree of stenosis. However, secondary angiography showed secondary occlusion in 88% of cases. These preliminary results show: the immediate efficacy of Argon laser in reducing the size of atheromatous plaques, the innocuity of the method as there were no postoperative deaths, a high incidence of secondary failure which could be related to the type of indication (competitive flow in the first group and poor distal run off in the second group of patients) or to the type of laser used. The authors consider this to be a promising technique but a lot of clinical and experimental work remains to be done before it can be adopted for routine use.

Aged↗
PubMed1985

Combined treatment in adenocarcinoma of cervix.

From January 1976 - end of 1979, 427 patients with cervical cancer were treated in the Department of Gynaecology, University of Hong Kong. Twenty-seven (6%) had primary adenocarcinoma of cervix. Eighteen patients with stage I and early stage II were treated by preoperative irradiation and Wertheim hysterectomy. Serial cervical biopsies were taken to assess the response to radiotherapy. All the cervical biopsies as well as the surgical specimens were read by the same pathologist. 83% showed residual dividing tumour cells in the surgical specimens. One hundred and forty-five patients with early squamous cervical cancer were similarly treated during the same period; only 13% had residual tumour in the specimens (chi square test p is less than 0.001). All the patients are being followed up regularly. Fifteen patients with early cervical adenocarcinoma are free from disease. The shortest period of follow-up is 5 1/4 years.

Adenocarcinoma↗
PubMed1984

Early and long-term results of coronary artery bypass grafting with severely depressed left ventricular performance.

The effects of coronary artery bypass grafting (CABG) on ventricular performance and long-term clinical status were studied in 18 consecutive patients with disabling angina pectoris and severely depressed left ventricular (LV) performance (ejection fraction [EF] 27 +/- 9%). All patients survived CABG, although 1 patient had a perioperative myocardial infarction. There was no change in LVEF at rest, 29 +/- 12%, in the other 17 patients. However, LVEF during peak exercise increased from 22 +/- 7% to 27 +/- 14% (p less than 0.05). The 17 patients were separated into 2 groups: those who increased their peak exercise LVEF by at least 10% (group A, 8 patients) and those who increased it by less than 10% (group B, 9 patients). Preoperatively, patients in group A had a higher LVEF at rest (p less than 0.001) and smaller end-systolic and end-diastolic volumes at rest (p less than 0.001) and during exercise (p less than 0.005). Preoperatively, the LVEF in group A decreased with exercise, from 36 +/- 4% to 27 +/- 5% (p less than 0.01), but was unchanged in group B (19 +/- 3% vs 17 +/- 4%, difference not significant). After CABG, patients in group A had a smaller increase in end-systolic volume with exercise than those in group B (13 +/- 7 vs 34 +/- 22 ml/m2, p less than 0.05), but the changes in end-diastolic volume with exercise were not significantly different. At 27 +/- 5 months after CABG, 5 of 8 patients in group A were asymptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Unexpected gallium uptake in benign pulmonary pathology. Report of two cases.

Two cases in which pulmonary gallium uptake was demonstrated in benign conditions are reported. In one, the abnormality permitted localization of a benign mesothelioma, while in the other patient it was associated with pulmonary fibrosis resulting from therapeutic irradiation. These cases extend the causes of gallium accumulation in which neither malignancy nor infection is responsible.

Aged↗
PubMed1984

Salivary scanning in rheumatoid arthritis with sicca syndrome.

Forty-nine patients were studied prospectively by salivary scanning to assess the value of this investigation in possible Sjögren's syndrome (SS). Twenty-three had rheumatoid arthritis (RA) with sicca symptoms and a positive Schirmer's test. Fifteen had RA with no sicca symptoms and a negative Schirmer's test. Eleven had osteoarthrosis (OA) with no sicca symptoms and a negative Schirmer's test. Scanning differentiated only poorly between the three groups. We conclude that it has only limited application in the diagnosis of SS associated with RA.

Adult↗
PubMed1984

Cholescintigraphy in acute cholecystitis: use of intravenous morphine.

Conventional cholescintigraphy (60 patients) and a modified protocol (59 patients) were compared in 74 females and 45 males with acute cholecystitis. In the modified protocol, intravenous morphine (0.04 mg/kg) was administered whenever the gallbladder was not seen 40 minutes after injection of Tc-99m-pyridoxylideneglutamate (36/59). Accuracy was 98% with morphine, compared with 88% for the conventional protocol; specificity improved from 83% to 100% with no loss of sensitivity (96% in both groups). Low doses of morphine are well tolerated and can result in a highly accurate diagnosis of acute cholecystitis without the need for delayed imaging.

Acute Disease↗
PubMed1983

Early left ventricular dysfunction and chelation therapy in thalassemia major.

Exercise radionuclide angiography was used to assess the incidence of subclinical abnormalities of left ventricular function in 23 asymptomatic patients with thalassemia major. Left ventricular ejection fraction (LVEF) at rest was normal in 18 patients and abnormal in 5. A normal LVEF response during exercise was shown in only 5 of the patients with normal resting left ventricular function. A normal response during exercise occurred more often in those patients who had received a smaller transfusional iron load and had a lower serum ferritin level (p less than 0.05). Twelve of the twenty-three patients were receiving chelation therapy with subcutaneous deferoxamine. Ejection fraction at rest was normal in 11 of these patients. During exercise a normal ventricular response was shown in 4 patients. After 1 year of intensive chelation therapy in these 12 patients, left ventricular function was reassessed. A normal exercise response was seen in an additional 4 patients; 3 of these showed an increase in peak exercise LVEF, and in the remaining patient no change of peak exercise LVEF was shown. The response during exercise was unchanged in 3 patients and had deteriorated in 1 patient.

Adolescent↗
PubMed1982

First-pass radionuclide angiocardiography in the determination of left-to-right cardiac shunt site in children.

To ascertain if the level of a left-to-right cardiac shunt can be reliably established by first-pass radionuclide angiocardiography with 99mTc-pertechnetate, 102 children have been studied; 19 without a shunt, 26 with an atrial septal defect (ASD), 45 with a ventricular septal defect (VSD), and 12 with a patent ductus arteriosus (PDA). Time-activity curves were generated over the right atrium and ventricle, and several quantitative parameters were derived from the curves. It was concluded that in the absence of right-sided valvular incompetence, the time-activity curves show the greatest abnormality in the cardiac chambers distal to the left-to-right shunt. The right ventricular curve is typically altered in ASD but cannot be relied upon to differentiate VSD or PDA. The identification of ASD is assisted by the use of two of the parameters, the count ratio C4:C1 and time ratio T2-T1.

Adolescent↗
PubMed1981

The effect of iron on the biodistribution of bone scanning agents in humans.

Nine patients with chronic iron overload, resulting from either repeated transfusions or hemochromatosis, had bone scans that were characterized by a reduction of bony uptake, marked increase in renal activity, and a significant increase in soft-tissue accumulation of 99mTc-labeled bone-seeking agents. These findings were supported by semiquantitative computer analysis. The probable mechanisms of altered biodistribution and the possible role of serum ferritin are discussed. The importance of realizing the effect of excess iron on skeletal scintigraphy is further emphasized by the results of bone scanning in another patient in whom acute iron overload following infusion of iron-dextran resulted in excessive blood pool labeling.

Adolescent↗