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Biomedical subjects

E Chan

Publications and source records attributed to E Chan.

At least 145 records · Page 8Linked to original sources
PubMed1987

Alternating cycles of etoposide plus cisplatin and VAB-6 in the treatment of poor-risk patients with germ cell tumors.

A phase II trial of 6 months of alternating etoposide plus cisplatin (EP) and cyclophosphamide, vinblastine, actinomycin D, bleomycin, cisplatin (VAB-6) was conducted in 41 evaluable patients in an attempt to improve the treatment results in those patients considered to have "poor-risk" germ cell tumors (GCT). Eight of 14 (57%) patients with mediastinal and retroperitoneal GCTs achieved complete remission (CR), and five (36%) remain alive and free of disease. Fourteen of 27 patients (52%) with poor-risk testicular cancer achieved CR, and ten (37%) remain alive and free of disease. Two patients with seminoma, one each with a testicular and extragonadal primary tumor, achieved durable CRs. Toxicity was tolerable, but greater than that of VAB-6 alone. The response and survival of the 39 patients with nonseminomatous tumors were found to be identical to the results of 29 patients with nonseminomatous GCTs and poor-risk characteristics who were treated with VAB-6 alone. Thus, this 6-month schedule of alternating months of chemotherapy is not recommended for patients with poor-risk GCTs. Patients with such tumors should be referred to centers conducting prospective trials, so that research seeking better therapy may continue.

Adolescent↗
PubMed1987

Gallium nitrate in prostatic cancer: evaluation of antitumor activity and effects on bone turnover.

Gallium nitrate, an agent known to inhibit bone resorption, was evaluated in patients with bidimensionally measurable hormone-refractory prostatic cancer. The starting dose was 200 mg/m2 iv by continuous infusion over 7 days. Two patients (10%; 95% confidence limits, 0%-22%) achieved short partial remissions of 1 and 6+ months, while seven of 23 (30%; 95% confidence limits, 14%-52%) showed a diminution of bone pain. Serial indices of bone turnover including serum calcium, phosphorus, and urinary hydroxyproline excretion showed a significant decrease at the completion of the infusion which returned to baseline prior to the next cycle. The data suggest the effect on bone was too short to produce consistent improvement. Reasons for the dissociation of pain relief and antitumor activity are discussed.

Adenocarcinoma↗
PubMed1986

Efficacy and safety of recombinant hepatitis B vaccine in infants born to HBsAg-positive mothers.

Infants born to HBsAg-positive women were randomly assigned to receive either the plasma-derived hepatitis B vaccine or the yeast-derived recombinant hepatitis B vaccine within 12 h of birth, simultaneously with HBIg. The second and third doses of both vaccines were given at 1 and 6 months of age respectively. Two hundred and twenty-two infants received two doses, and 80 infants received three doses of either vaccine. Five infants were found to be HBsAg-positive at 6 months of age. Four of these infants had received the plasma vaccine and the remaining infant the recombinant vaccine. Anti-HBs was present in all the HBsAg-negative infants at 6 months of age. The titres of anti-HBs were similar in both groups of infants who had received either the plasma or the recombinant hepatitis B vaccine. No major adverse reactions were reported with either vaccine. The preliminary results from this study suggest that the yeast-derived recombinant hepatitis B vaccine is safe, immunogenic and at least as effective as the plasma-derived hepatitis B vaccine in preventing the HBsAg carrier state in infants born to HBsAg-positive women.

Carrier State↗
PubMed1985

Characteristics of the capillary-free zone in the normal human macula.

The dimensions of the foveal avascular zone (FAZ) were determined on fluorescein angiograms in 45 normal subjects, 25 men and 20 women, by means of a digital image processing system. The shape of the FAZ was usually irregular and showed considerable individual variations. The mean longest diameter was 0.88 +/- 0.16 mm (SD), the horizontal diameter was 0.73 +/- 0.15 mm, vertical diameter was 0.70 +/- 0.17 mm and the area averaged 0.43 +/- 0.16 mm2. The area of the FAZ and the age of the subjects showed a statistically significant positive correlation (r = 0.383, P less than 0.005). The enlargement of the FAZ with advancing age may be related to senescent changes of the retinal capillaries. It was stressed that it is of importance to measure the size of the FAZ by fluorescein angiography before laser photocoagulation is carried out near the macular region.

Adolescent↗
PubMed1985

Characteristics of the macular microvasculature.

The morphological appearance and the quantitative analysis of the structure of the macular microvasculature were investigated in 33 normal subjects by fluorescein angiography and stereoscopic mapping techniques. The foveal capillary network was formed by the anastomosis of 4 to 6 groups of terminal arteriolar and venous branches. The inner three rings of capillaries were a single layer of microangium. The apertures of the network differed in size and the closer to the foveal avascular zone, the larger were the apertures. The mean inner width of the capillaries in the fovea was 12.99 +/- 2.2 (SD) microns, and it was 24.55 +/- 6.51 microns on the edge of the fovea. There was a strikingly regular pattern of 4 to 6 arterioles with associated venules. The inner diameter of the smaller vessels on the edge of this area was 35.17 +/- 6.41 microns. In the external perifovea, the arterial and venous branches increased in number to more than 12 and the diameter of these vessels was 4.5 times larger than that of the capillaries in the fovea. The characteristics of the macular microcirculation provide a basis for studying macular disease, particularly the pathogenesis of vascular disorders.

Adolescent↗
PubMed1984

Effect of polyglycolic acid microsuture on rat uterine anastomoses.

In order to observe the effectiveness of polyglycolic acid microsutures (Dexon on rat uterine anastomoses, 40 Lewis rats were subjected to two-layer (including the mucosa) and one-layer (avoiding the mucosa) interrupted anastomoses of the freshly severed uteri using Dexon sutures. They were killed at days 7, 14, 21, 30, 60, 90, 180, 270, and 360. There was intensive inflammatory reaction during days 7-14 that gradually subsided, and the inflammatory reaction was limited to the suture sites by days 21-30. Sutures were still detectable at the end of 2 months, but they were no longer recognized at the end of 3 months. As the sutures were completely absorbed, giant cells and granulomatous reactions completely cleared. By days 180, 270, and 360, the rat uteri in both groups were indistinguishable from nonoperated ones. In this observation, it was noted that the use of absorbable microsutures with the mucosa inclusion in the rat uterine anastomoses was equally effective as those without the mucosa, and Dexon microsutures showed no residual effects on the uterine reanastomoses.

Absorption↗
PubMed1984

The development of an Assertiveness Self-Report Inventory.

The development of a self-report measure of assertiveness is described. The Assertiveness Self-Report Inventory (ASRI) was devised with concern for endorsement frequency, internal consistency, and independence from social desirability response bias. The scale's reliability and convergent and discriminant validity are adequate. Further tests of validity support the use of the scale as a measure that taps behavior related to the construct of assertiveness.

Journal Article↗
PubMed1983

Efficacy of polyglycolic acid (Dexon) microsutures in peripheral nerve anastomoses in the rat: 1. Epineural suture.

The efficacy of polyglycolic acid (Dexon) microsuture in peripheral nerve repair was studied using 84 and 28 reanastomoses of freshly severed rat sciatic nerve employing Dexon and nylon 9-0 interrupted epineural suture technique. Animals were sacrificed and sutured portions of the nerves were histologically examined. There were almost identical suture reactions by day 7, except that the intensity of polymorphonuclear (PMN) and macrophage infiltrate in the nylon-sutured nerves was far greater than in the Dexon-sutured group. Although the intensity of the nylon-suture reaction subsided considerably after day 21, the lymphocytes, macrophages, and plasma cells surrounded the suture as long as the sutures remained in the nerves up to 12 months postoperatively. The Dexon-sutured nerve segments showed disappearance of the inflammatory cells as soon as the sutures were completely absorbed. The Dexon sutures were still detectable at months 1 and 2 but not after month 3.

Animals↗
PubMed1983

Phenylbutazone-warfarin interaction in man: further stereochemical and metabolic considerations.

The pharmacokinetics and urinary metabolic profile of R and S-warfarin, following administration of a 1.5 mg/kg oral dose of racemic warfarin, alone and 4 days into an oral regimen of 100 mg phenylbutazone three times a day, was investigated in three volunteers using a stereospecific h.p.l.c. fluorescent assay. The mean elimination half-life of S-warfarin was increased from 25 to 46 h during phenylbutazone administration, whilst that of the R-isomer was decreased from 37 to 25 h. The peak unbound concentrations of both warfarin enantiomers were higher during phenylbutazone administration, due to displacement. Displacement was not stereoselective. The unbound clearance of more potent S-warfarin is decreased by four-fold during phenylbutazone administration, due to substantial inhibition of both 6- and 7-hydroxylation, significant pathways of elimination of S-warfarin in the absence of phenylbutazone. The unbound clearance of R-warfarin is almost unchanged during phenylbutazone administration, due to the marginal effect of phenylbutazone on 6- and 7-hydroxylation, themselves minor pathways of elimination of this enantiomer in the absence of phenylbutazone. The stereoselective reduction of S- and R-warfarin, to their respective SS and RS-alcohols, is also substantially inhibited during phenylbutazone administration. Collectively the data point to the complex effect of phenylbutazone administration on warfarin's pharmacokinetics.

Drug Interactions↗
PubMed1982

Enhanced neophobia but normal plasma corticosterone levels in rats with dorsal noradrenergic bundle lesions.

The effects of dorsal noradrenergic bundle (DNB) lesions on plasma corticosterone levels were determined in male albino rats. DNB lesions did not affect baseline plasma corticosterone levels. Furthermore, the increased corticosterone levels produced by various environmental manipulations did not differ between control and DNB lesioned groups. However, the lesioned group did exhibit longer latencies to eat familiar food in novel environments, as well as to eat novel foods in a familiar environment. Latencies to eat novel food in novel environments did not differ between the two groups and this was attributed to a "ceiling" effect. These endocrinological data fail to support the hypothesis that the enhanced "neophobia" observed in DNB lesioned rats is due to an increase in the intensity of the emotional reaction to novel stimuli. The data do not preclude the possibility, however, that the enhanced neophobic reactions reflect impaired habituation to these stimuli.

Animals↗
PubMed1981

Osteonecrosis in patients irradiated for head and neck carcinoma.

One hundred patients irradiated for cancers of the oral cavity, oropharynx, and nasopharynx were evaluated for the occurrence of osteonecrosis and associated predisposing factors. Selection was based on availability of complete dental records, a minimum of six months follow-up, and treatment fields, which included maxilla and/or mandible. Bone doses were calculated by using radiotherapy treatment records, port films, and isodose distributions. Osteonecrosis developed in 19 of 78 dentulous patients and in 3 of 22 edentulous patients. The time of development of osteonecrosis varied; in 15 cases osteonecrosis occurred more than one year after treatment. The most important risk factor for the development of osteonecrosis was the radiation dose to bone, particularly in the less vascular mandible. Osteonecrosis 7500 rads to the bone. None of the patients who received less than 6500 rads developed osteonecrosis. The risk was significantly greater when teeth were removed after therapy compared with those individuals with extractions before radiation or no extractions at all.

Head and Neck Neoplasms↗