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Biomedical subjects

T D Nguyen

Publications and source records attributed to T D Nguyen.

At least 145 records · Page 8Linked to original sources
PubMed1985

Transmissible gastroenteritis (TGE) of swine: survivor selection of TGE virus mutants in stomach juice of adult pigs.

Two transmissible gastroenteritis (TGE) virus mutants (188-SG and 152-SG) were obtained from a low-passage virus strain (D-52) by 188 and 152 cycles of stomach juice treatment and multiplication in cell culture. Compared to the high-passage Purdue-115 and the original D-52 strains, these mutants were more stable at pH 2.0, more resistant to pepsin and trypsin, and characterized by a small plaque phenotype. In vivo, the two mutants were not found to be virulent for 4-day-old piglets and sows after oral inoculation. To test induction of lactogenic immunity, the 188-SG mutant was administered orally to pregnant sows (6 or 7 weeks before parturition) followed by one intramuscular booster (1 week before parturition). After challenge with virulent TGE virus, piglet mortality 7 days after exposure was reduced (to 22%) as compared to the death rate in piglets from control sows (91%).

Animals↗
PubMed1984

Apolipoproteins as the basis for heterogeneity in high-density lipoprotein2 and high-density lipoprotein3. Studies by isoelectric focusing on agarose films.

A method is described for the isoelectric focusing (IEF) of lipoproteins on thin films of agarose. Within a pH gradient of 4.60-5.30 both high-density lipoproteins 2 and 3 (HDL2 and HDL3) are resolved into more than 10 fractions which could be stained either for protein or for lipids. The isoelectric focusing patterns for HDL2 and HDL3 are similar although HDL2 appears richer in the more alkaline bands. Narrow film strips from the IEF separation of HDL2 and HDL3 were interfaced with various agarose plates containing antisera against apolipoproteins apoAI, apoAII and apoCIII either alone or in combination, to provide two-dimensional IEF immunoelectrophoresis patterns. This technique demonstrated that apoAI and apoAII were present throughout the IEF gel for both subclasses of HDL. It also provided evidence for the existence of lipoproteins containing both apoAI and apoAII and other lipoproteins present in the alkaline region of the gel which contained apoAI but no apoAII. ApoCIII was found mostly in acidic lipoproteins and was not distributed identically in HDL2 and HDL3. The lipoproteins separated by IEF on agarose were also analysed by two-dimensional IEF-SDS electrophoresis and the individual apolipoproteins were identified by reaction with antibodies to apolipoproteins AI, AII, CI, CII, CIII, D, and E. This technique confirmed that in IEF of HDL, apoAI extended throughout the spectrum of lipoproteins whereas apoE was only present in alkaline lipoproteins and apoD was only present in acidic lipoproteins. IEF on agarose of either HDL2 or HDL3 allowed us to collect eight different fractions, which have the same pI in either lipoprotein class. The apolipoprotein composition of each isolated band was analysed by electroimmuno-assays for apolipoproteins AI, AII, CI, CII, CIII, D, and E and the results expressed as the ratio of the measured apolipoprotein to measured apoAI. In both HDL2 and HDL3, acidic lipoprotein fractions were enriched in apoAII, apoCIII and apoD. ApoCII and apoCII were not similarly distributed in HDL2 and HDL3 subfractions whereas the apoCI distribution was similar in both classes. Noteworthy in all experiments was the difference in the distributions of apoCI, apoCII, and apoCIII in HDL2 and HDL3, which indicated that the existence of a lipoprotein containing simultaneously CI, CII and CIII can only account for a small fraction of these apolipoproteins. Therefore these experiments substantiate the theory of the protein basis of HDL heterogeneity and suggest that the majority of apolipoproteins are present in complexes which upon IEF result in lipoprotein fractions of identical pI for both HDL2 or HDL3.(ABSTRACT TRUNCATED AT 400 WORDS)

Apolipoproteins↗
PubMed1984

Hyperfractionated radiotherapy with or without misonidazole: results of a prospective randomized study in stage III-IV squamous cell carcinoma of the head and neck.

From 1979 to 1980, 52 patients with Stage III-IV squamous cell carcinoma of the head and neck were included in a prospective randomized study on hyperfractionated radiotherapy with or without misonidazole. The radiotherapeutic schedule consisted of two weeks of treatment split by a rest-period of one month, 6 X 1.1 Gy fractions per day for 5 consecutive days (total dose: 2 X 33 Gy/30 f/5 d). Total dose of misonidazole was 12 g/m2 administered daily in 1.2 g/m2 fractions. The overall tolerance of misonidazole was good, with a neuropathy rate of 5.7%. Local control, recurrence and 3 year survival rates did not statistically differ between the two groups. The randomized trials published at the present time, including our own, suggest that misonidazole has no beneficial effect with classical, concentrated or multiple fractions per day radiotherapy.

Aged↗
PubMed1984

The use of a concomitant electron boost (field in the field technique) in large cervical node metastases over a shortened period.

Seven patients with large cervical node metastases were treated at the Institut Jean-Godinot using a particular scheme of accelerated irradiation. Conventional Cobalt-60 radiotherapy was prophylactically delivered to extended volumes of the neck (50 Gy in 25 fractions over 5 weeks). Within the fields of cobalt irradiation, an electron beam field was added to increase the daily dose from 2 to 3 Gy (Fletcher's field in the field technique). The increment of dose was limited to nodal area. Since no interval separated the two irradiations, involved areas were considered to receive 70 Gy in 25 fractions over 5 weeks and non-clinically involved areas to receive 50 Gy in 25 fractions over 5 weeks. In all the cases, the malignant mass diameter exceeded 5 cm. Acute tolerance was good and no major late injury was observed during the 18 months minimum follow-up period. At the end of the treatment, a complete disappearance of the tumor was observed in six out of seven cases. At the present time, four patients are still alive without evidence of disease. Slight acceleration of irradiation by the use of a concomitant electron boost is easily feasible and may provide an improvement in local control and therapeutic ratio of large cervical malignant masses in the neck.

Aged↗
PubMed1983

Enhancing the utilization of outpatient mental health services.

This article describes two sets of field studies undertaken by the program evaluation unit of a community mental health center. These studies analyzed clients' utilization of service and assessed service impact in the process of testing procedural variations in service delivery. In the first set of studies, a procedure for ensuring verbal client-therapist contact prior to the first appointment was developed and tested. This procedure reduced the no-show rate for initial appointments from 22 to 12%. In the second set of studies, a brief pretherapy orientation nearly eliminated dropout during the first month of therapy. Orientation had both short- and long-range impact on the amount of services used by clients as well as on their outcomes. Therapist's global ratings of client functioning reflected more change for oriented clients, who reported greater short-term symptom reduction as well. Non-oriented clients were more likely to drop out early and to impress their therapists less favorably. The results of these studies suggest that a combination of pretherapy orientation and verbal client-therapist contact prior to the initial appointment might greatly reduce the failure to complete treatment.

Community Mental Health Services↗
PubMed1983

Assessment of patient satisfaction: development and refinement of a service evaluation questionnaire.

A series of seven studies was conducted by the authors and their colleagues to produce an efficient measure of service satisfaction that can easily be related to symptom level, demographic characteristics, and type and extent of service utilization. The resulting measure, the Service Evaluation Questionnaire (SEQ) is a brief, global index that has excellent internal consistency and solid psychometric properties. Data from an extensive SEQ field study can be used as a comparison base for future applications of the two SEQ component scales, the CSQ-8 and the SCL-10. A new hypothesis has emerged from this series of studies that will guide future research: Service recipients may find if difficult to formally express dissatisfaction in the face of significant caring--however ineffectual--when the technical capacity to offer definitive treatment is not yet fully developed and when criteria for evaluating the efficacy of treatment are not yet crystal clear.

Analysis of Variance↗
PubMed1983

Hyperfractionated radiotherapy in advanced squamous cell carcinoma of the head and neck.

From January, 1976 to January, 1980, 141 patients (135 males and 6 females) with Stage III and IV squamous cell carcinoma of the head and neck received a split course of hyperfractionated radiotherapy (HFR). In the first group, involving 91 patients, the therapeutic schedule was as follows: first and fourth week, 7.2 Gy per day in 8 sessions of .9 Gy from Monday to Friday, the second and third week no irradiation was given. Thus, patients were given 72 Gy total dose, fractionated into 80 sessions. Mucosal necrosis and severe hemorrhage were responsible for the death of 26 patients (28%). Therefore the therapeutic protocol was altered for the 50 patients of the second group: during the first and sixth week 6.6 Gy per day in 6 sessions of 1.1 Gy from Monday to Friday. The total dose was thus reduced to 66 Gy fractionated into 60 sessions, resulting in the decrease of toxicity. Regardless of the therapeutic protocol and site of primary, 114 patients (80%) achieved a complete remission and 8 showed a partial remission (greater than 50%), whereas no change was seen for the 19 remainders. Local recurrence appeared in 60 patients (48%). Acute mucositis and laryngeal edema regularly occurred a week after every course of HFR and were considered severe in 40 patients. In spite of toxicity, the median survival is 14 months and 22 patients are still alive in November 1981: 19 without disease, and 8 of these patients have a survival time of at least 3 years.

Adult↗
PubMed1982

Postoperative irradiation of carcinoma of the head of the pancreas area: short-time tolerance and results to precision high-dose technique in 18 patients.

During the period from January 1977-August 1979, 18 patients with biopsy-proven pancreas duct or ampullary adenocarcinoma with no distant or liver metastases underwent external beam radiation therapy following laparotomy. With the use of a 25 MEV photon beam and a four field "box" technique, the dose delivered to the target volume identified with radio-opaque clips at laparotomy was 6000 rad in six weeks, while largely sparing the spinal cord, kidney, liver and gut. All patients subjected to low fat, gluten free diet completed treatment as planned without any acute reaction. Three patients developed delayed pancreatic insufficiency. According to actuarial survival analysis and low morbidity such an approach may lead to increase survival in patients with pancreatic cancer.

Adenocarcinoma↗
PubMed1982

[Primary tumors of the renal pelvis and ureter: value of postoperative external radiotherapy (author's transl)].

Twenty-four observations of primary malignant tumors of the renal pelvis and ureter derived from epithelial cells were included in this study. Thirteen patients were treated by radiotherapy and surgery. In eleven patients, surgical excision was the only treatment. Although patients were not randomized there was no significant difference between the two groups concerning the following parameters: age distribution, sex ratio, stage of disease, histological grade, surgical procedure. The morbidity related to external radiotherapy (megavoltage technique, delivering 45 grays in 5 weeks) was low: only one patient developed retroperitoneal fibrosis. No patient was lost to follow-up. Local recurrence occurred in 54.5% of the patients treated by surgery alone, against 15.5% after combined radio-surgical therapy. The overall three-year survival rate was 35% without any significant difference between the two groups. The authors advocate postoperative high-voltage radiotherapy for non-disseminated carcinoma of the renal pelvis and ureter.

Adult↗
PubMed1982

Enhancing program review for evaluation and management.

Program review has not received the attention it warrants as a program evaluation tool despite its wide use for evaluation and management purposes. The use of the program review will probably endure on the strength of its face validity and irrespective of other developments in the field of program evaluation. Evaluators should realize this and, accordingly, attempt to improve its effectiveness. This paper presents one organization's approach to achieving this objective through the explication of development principles, implementation guidelines and review items. This paper also discusses benefits that can be expected from a systematic development of this tool and presents various research directions and potentials in this area.

Community Mental Health Services↗
PubMed1981

Purification, physical characterization, and NH2-terminal sequence of glutamine synthetase from the cyanobacterium Anabaena 7120.

A procedure for the complete purification of glutamine synthetase (L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2) from the cyanobacterium (blue-green alga) Anabaena 7120 is described. The enzyme has structural characteristics in common with glutamine synthetases from other sources: a subunit molecular weight of approximately 50,000 and a native structure, determined by low dose exposure electron microscopy, consisting of a two-layered regular hexagon made up of 12 subunits. Sequence analysis suggests that the subunits are identical. There was no indication that the enzyme from cyanobacteria is adenylylated, a feature shared with the glutamine synthetase from Bacillus subtilis but not with the enzyme from Escherichia coli. NH2-terminal sequence analysis and the predicted conformation of the NH2-terminal regions showed definite homology among the enzymes from all three sources. The limited analysis suggested a stronger structural homology between the enzyme from Anabaena 7120 and that from E. coli.

Amino Acid Sequence↗