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Biomedical subjects

R Gonin

Publications and source records attributed to R Gonin.

66 records · Page 4Linked to original sources
PubMed1992

Gallium imaging in metastatic and recurrent soft-tissue sarcoma.

Fifty-six patients with metastatic or recurrent soft-tissue sarcoma were evaluated by 67Ga-citrate imaging. Prior to entry on the therapy protocol, 52/56 (93%) patients had true-positive 67Ga studies. Two of four patients with liposarcoma, one of twelve with leiomyosarcoma and one with an epithelioid sarcoma had false-negative studies; 89/105 disease sites (85%) were 67Ga positive, including 100% of pleural lesions, 94% in bone, 88% in the abdomen, 85% in soft tissue, 78% in lung parenchyma and 56% of liver metastases. There was significant association between 67Ga avidity and tumor grade with the exception of mesothelioma. No relationship was seen between 67Ga avidity and tumor cell type, disease site or lesion size. Following therapy, 67Ga correctly identified 11/12 sites of active disease in 8/9 patients. Mean pre- and post-therapy 67Ga avidity scores did not differ significantly. Gallium-67 appears to have an important role in the evaluation of patients presenting with either primary or metastatic soft-tissue sarcoma.

Adolescent↗
PubMed1991

The effect of nifedipine on fetal umbilical artery Doppler waveforms in pregnancies complicated by hypertension.

The effect of nifedipine 5 mg administered sublingually to pregnant hypertensive patients was examined in a randomised controlled double-blind study. The effect on maternal blood pressure and the fetal umbilical artery Doppler waveform was studied for 30 minutes before and 30 minutes after administration of the drug or placebo. This dose resulted in a significant drop in maternal blood pressure 30 minutes after administration and did not result in a significant change in the Doppler umbilical artery waveform (in fetuses with normal waveforms) when compared with a control group.

Blood Flow Velocity↗
PubMed1991

Phase II trial of trimetrexate in patients with advanced soft-tissue sarcoma.

Trimetrexate, a lipophilic, 2,4-diaminoquinazoline derivative of methotrexate, enters cells by passive diffusion rather than via a transport system. Trimetrexate has shown promising activity in animal model systems. A total of 16 patients with metastatic soft-tissue sarcoma who had received only one prior chemotherapy regimen were treated with trimetrexate (8 mg/m2 given intravenously daily for 5 days) every 3 weeks. Treatment-related toxicity included greater than or equal to grade 2 neutropenia (8/16), thrombocytopenia (3/16), mucositis (4/16) and skin rash (3/16). No partial or complete responses were observed in 15 evaluable patients (95% confidence interval for true response rate, 0-22%) Six subjects showed stabilization of disease for periods ranging from 2 to 9 months. At this dose and on this schedule, trimetrexate appears to have little activity against refractory soft-tissue sarcomas.

Antineoplastic Agents↗
PubMed1991

Fluorouracil and high-dose leucovorin in previously untreated patients with advanced adenocarcinoma of the pancreas: results of a phase II trial.

Forty-two previously untreated patients with advanced, measurable adenocarcinoma of the pancreas were treated with weekly fluorouracil (5-FU; 600 mg/m2 intravenous [IV]) and leucovorin 500 mg/m2 IV for 6 weeks followed by a 2-week rest. A median of 11 (range, one to 76) doses were given. There were three partial responses (three of 42 [7%]; exact 95% confidence interval, 1% to 19%) and no complete responses. Median survival was 6.2 months, with seven patients surviving longer than 12 months. The most common toxicity was diarrhea; there was one treatment-related death. Despite promising results in patients with advanced colorectal cancer, this dose schedule of 5-FU and leucovorin does not appear to be superior to 5-FU alone for the treatment of advanced pancreatic cancer. Alternative investigative approaches are needed.

Adenocarcinoma↗
PubMed1990

Dosimetry of swallowed non absorbed 99mTc radiopharmaceuticals in pediatric patients.

A calculation is presented which derives the absorbed dose experienced by pediatric patients of different ages who swallow a non absorbable 99mTc compound. All previous models assume sudden movement of radionuclide from one compartment of the gastrointestinal tract to another. The present model is novel in considering continuous distal motion through the gut and so more closely approximates the physiologic situation. Published S values are used to derive absorbed doses. The resulting calculated absorbed doses are comparable to, or lower than, those previously published and these differences are most marked in the large gut, which remains the critical organ.

Child↗
PubMed1988

Computed limitations of spot scanning for therapeutic proton beams.

A calculation depending on the computed fit of a novel mathematical model of the depth dose distribution for a therapeutic proton beam in water and its relevance to a spot scanning system are described. The resulting requirements for lateral and longitudinal precision of the irradiated spots are derived using the standard criterion for allowed dose variation within the tumour volume and the implications of these exacting limits are discussed.

Computer Simulation↗
PubMed1988

The distribution of health needs and services in South Africa.

The authors recognize that social, economic and political factors play a larger role in determining public health policy than do epidemiological principles such as the analysis of needs, demand and supply. Nevertheless, demographic and mortality statistics, information from the 1983 registers of medical and dental practitioners, and that of nurses, as well as information on hospital beds were reviewed to describe health care requirements and resources in South Africa. The maldistribution observed in health needs and services closely parallel the divisions in South African society imposed by the apartheid policy. It is concluded that fundamental political change is required to reduce this maldistribution. The provision of preventive and promotive health services for children in African rural and peri-urban areas was identified as a health care requirement of high priority. It is thought that the need in these geographical regions might best be met by employing primary health care workers at a lower level of training than doctors with an accessible, supporting referral system. In addition, the quality of health care data being collected needs to be improved. It is suggested that both these problems be approached on a regional basis, and preferably under a single health authority, rather than the current fragmented health service.

Demography↗
PubMed1987

Primate endocrine function after pancreatico-duodenal-splenic allotransplantation.

In this study the endocrine function following intraperitoneal hetero- and orthotopic pancreatico-duodenal-splenic allotransplantation (PDS) in hemipancreatectomized, non-immune-suppressed chacma baboons was assessed. Significantly reduced K-values and insulin release together with glucose intolerance during IVGTT were observed in hemipancreatectomized recipients (HPS) without grafts. Orthotopic and heterotopic PDS transplantation improved the glucose intolerance of HPS recipients; orthotopically sited grafts rendering the best curves. Normal glucose tolerance was not achieved. Both orthotopic and heterotopic PDS transplantation rendered suboptimal insulin release during IVGTT; heterotopically draining grafts released significantly more insulin than orthotopic grafts. Hyperglucagonaemia during IVGTT was a constant feature in both groups, heterotopic grafts releasing the most glucagon during stimulation. C-peptide release was significantly lower in orthotopic grafts compared to normal animals or heterotopically drained insulin. It is concluded that glucose tolerance was not directly related to insulin or glucagon release in this study as orthotopic grafts rendered near-normal IVGTT curves in the presence of hypoinsulinaemia, hyperglucagonaemia, and reduced C-peptide values. The hormonal response after PDS transplantation was variable and the advantages of portal vs systemic insulin drainage remain to be defined.

Animals↗
PubMed1986

How many doctors are needed in South Africa by 1990?

The 1983 register of medical and dental practitioners was used to describe the provincial and urban-rural distribution of non-specialist medical practitioners. The number of medical practitioners who will be registered in 1990 was estimated on the basis of current accrual and loss patterns. The number required by 1990 was estimated on the basis of the projected population growth using a linear prediction model in which the proportion of blacks resident in urban regions was varied. The requirements were based on doctor/population ratios either remaining as they were in 1980 or improving by 1990. We found that for South Africa there were 2 198 people per doctor. However, there were more people per doctor in rural regions than in urban regions, with the rural Cape Province the only rural region with fewer than 6 000 people per doctor. In black national states there were more than 14 000 people per doctor. There appears, therefore, to be a need for redistribution of medical practitioners to the rural regions. We estimated that, should doctor/population ratios in 1990 remain as they were in 1980 with only a modest increase in black urbanization, there would be enough medical practitioners registered in 1990 at current accrual rates. Should rural ratios be improved to 1:5 000 and urban ratios to 1:1 000 as proposed in the National Health Services Facility Plan, there will be fewer doctors registered than are needed in 1990, particularly if black urbanization increases markedly.(ABSTRACT TRUNCATED AT 250 WORDS)

Forecasting↗
PubMedDate not supplied

The detection of pulmonary metastases by helical CT: a clinicopathologic study in dogs.

PURPOSE: We sought to determine the accuracy of helical CT in the detection of pulmonary metastases. METHOD: Four anesthetized dogs with metastatic osteosarcoma underwent helical CT with a collimation of 5 mm, a pitch of 2, and a reconstruction interval of 5 mm. All macroscopically evident metastases were recorded at autopsy. CT images were independently reviewed by 10 radiologists and compared with pathologic results. Alternate slices in the dog with the most metastases were microscopically examined in their entirety. RESULTS: Pathologic examination of the lungs revealed 132 macroscopically evident pulmonary metastases, of which 74 (56%) were detected by at least one reader. Forty-four of the 99 (44%) metastases of < or = 5 mm in diameter were detected by at least one reader compared with 30 of 33 (91%) metastases of > 5 mm in diameter (p < 0.0001). The 10 readers reported a total of 107 false positives. Complete microscopy of alternate slices in the dog with the most metastases (n = 68) revealed an additional 38 micrometastases of < or = 3 mm in diameter. None of the 32 micrometastases of < or = 1 mm were detected by CT. CONCLUSION: Helical CT has some limitations in the detection of pulmonary metastases.

Animals↗
PubMedDate not supplied

Retrovirally mediated gene transfer of Arg22 and Tyr22 forms of dihydrofolate reductase into the hematopoietic cell line K562: a comparison of methotrexate resistance.

Mutations in the enzyme dihydrofolate reductase (DHFR) can confer resistance to the inhibitory effects of folate analogs such as methotrexate (Mtx) and trimetrexate (Ttx). Retroviral vectors expressing the DHFR-Arg22 mutants and the newly described DHFR-Tyr22 mutant were used to transduce the hematopoietic cell line K562. In vitro selection of vector-containing cells was documented via polymerase chain reaction and Southern analysis. When proliferation of selected vector-containing cells was evaluated over a range of Mtx concentrations (0.01 to 10 micromol/L), both Arg22 and Tyr22 provided protection from Mtx, but Tyr22 proved superior to Arg22 in conferring Mtx resistance at low concentrations. Ttx proved to be 10- to 100-fold more potent than Mtx in inhibiting proliferation of nontransduced K562, but the relative effectiveness of individual mutants in conferring drug resistance was similar to that of Mtx. Decreasing the amount of folate in the culture medium to more physiological concentrations increased the potency of administered Mtx and Ttx. Drug resistance in retrovirally transduced K562 cells is consistent with the enzymatic characteristics of the individual mutants. Our findings suggest that the new Tyr22 form of DHFR may prove better in conferring drug resistance than the previously reported Arg22 mutant.

Antimetabolites, Antineoplastic↗