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Biomedical subjects

B J Smit

Publications and source records attributed to B J Smit.

48 records · Page 3Linked to original sources
PubMed1989

The role of neutrons in the treatment of soft tissue sarcomas.

Two-hundred twenty-one patients with soft tissue sarcoma were treated from 1978 to 1983. Treatment was nonrandomized and consisted of neutron irradiation in 94 cases with gross tumor. Treatment was nonrandomized and consisted of neutron boost irradiation after photon-irradiation or electron-irradiation in 127 cases with no gross tumor after surgery. Patient distribution according to UICC (1978) criteria was 15, 100, and 106 of T1, T2, and T3 respectively. Distribution by pathologic grade was 54, 107, and 60 for Grade 1, Grade 2, and Grade 3 tumors. Distribution by tumor residuum after surgery was 23 cases without microscopic disease (R0), 104 with microscopic disease (R1), and 94 with gross residuum (R2) or nonoperative disease. Five-year follow-up reveals a significant difference (P = 0.024) in disease-free survival (DFS) for T1 (60%), T2 (71%), and T3 (29%, P = 0.016) tumors. Similarly, there are significant DFS differences among G 1 (74%), G 2 (48%, P = 0.035), and G 3 lesions (22%, P = 0.024). The impact of tumor bulk or residuum on DFS after operation is significant when comparing R0 (87%) and R1 (65%) disease (P = 0.042). The 5-year survival of patients who had gross residuum (R2) after surgery was significantly worse (26%, P = 0.003). Ninety percent of patients failed treatment locally and distally within 2 years. The late morbidity rate was 27% for neutron and 7% for neutron-boost irradiation. In our series and reported photon data, local control rates for tumors 5 to 10 cm with neutrons were 76% and 53%, respectively. Low energy (d(14) + Be) neutrons are considered beneficial in the postoperative treatment of well-differentiated soft tissue sarcomas where gross tumor remains. Neutron-boost irradiation is of potential benefit in the treatment after operation of T2-3, and G 1-2 tumors if there is microscopic residual tumor.

Adult↗
PubMed1989

[Repatriation of the prematurely born infant].

A preterm birth of a child during a holiday abroad may have serious consequences for child and parents. The neonate's repatriation and the problems it causes are discussed and illustrated by two case histories. The attending midwife, general physician or obstetrician may play a preventive part.

Delivery, Obstetric↗
PubMed1987

Irradiation damage in chromatin isolated from V-79 Chinese hamster lung fibroblasts.

The effect of chromatin structure on the extent of radiation damage induced by low doses of 100 KeV X rays was investigated using a fluorescent assay for DNA unwinding. Chromatin was isolated from V-79 Chinese hamster lung fibroblast nuclei by partial digestion with micrococcal nuclease. Gel electrophoresis of the isolated DNA showed the molecular weight of the chromatin preparation to be 10.6 X 10(6) with a size range of 6.6-21.7 X 10(6) Da while a size of 10.2 +/- 0.9 X 10(6) Da was found by sedimenting the DNA in alkaline sucrose gradients. The repeat length of V-79 chromatin was found to be 194 +/- 3 bp. The typical nucleosomal repeat structure of the isolated chromatin and that of intact nuclei was identical. Irradiation with 50 and 100 Gy of 100 KeV X rays and analysis by alkaline sucrose density centrifugation indicated that V-79 chromatin sustained 0.56 +/- 0.19 and 0.69 +/- 0.09 single-strand breaks per 10 Gy per 10(8) Da of DNA, respectively. Irradiation with doses of 0.5-3.0 Gy of 100 KeV X rays and analysis by the fluorometric assay showed that the radiation sensitivity of V-79 chromatin decreases sharply on compaction with MgCl2. Histone H1 depletion, which inhibits compaction and causes chromatin to expand by increasing the linker from 26 to 48 bp, results in a considerable increase in the radiation sensitivity. It is concluded that radiation damage sustained by DNA is greatly influenced by chromatin structure.

Animals↗
PubMed1984

Effect of irradiation and endogenous nucleases on rat liver chromatin.

These assessment of the consequences of irradiation on chromatin is complicated by endogenous nucleases. Isolation and prolonged storage of rat liver nuclei in buffers containing divalent metal ions activates these enzymes and promotes the degradation of chromatin. Irradiation of rat liver nuclei to dose levels of 20,000 rad under conditions in which endogenous nucleases are inhibited and analysis of the irradiated chromatin by sucrose density gradient centrifugation gave no evidence for monosomes or oligosomes. When chromatin from irradiated nuclei was digested with micrococcal nuclease, the levels of monosomes and oligosomes were identical to those of micrococcal nuclease, the levels of monosomes and oligosomes are identical to suggest that irradiation results in neither a direct fragmentation of linkers nor the sensitization of linkers for subsequent cleavage by micrococcal nuclease. Histones isolated from monosomes of irradiated and unirradiated nuclei were intact, showing no fragmentation or loss of residues, as judged by sodium dodecyl sulfate-polyacrylamide electrophoresis.

Animals↗
PubMed1983

The role of ultrasound in the management of cervical carcinoma. A preliminary report.

Thirty-five cases of carcinoma of the cervix were examined ultrasonographically in order to assess the role of ultrasound in the management thereof. The method is not sufficiently reliable to detect spread beyond the cervix, but does provide useful information regarding pelvic anatomy and the spatial relationships of the cervix. It can be advantageously applied in the planning of therapy and its use in the day-to-day management of such cases is recommended.

Cervix Uteri↗
PubMed1978

Peritoneoscopy in the management of breast cancer.

Peritoneoscopy has been recommended by the Combined Breast Clinic at the Provincial Hospital, Port Elizabeth, since 1975, mainly to confirm or exclude metastatic involvement of the liver. Experience with 27 procedures is reviewed. Peritoneoscopy is shown to be a useful aid in the staging and management of selected cases of breast cancer. Positive findings, confirmed by histological examination, were recorded for 5 patients. Negative findings in 22 patients were equally helpful, and were found to be reliable, in that none of these patients had evidence of liver involvement during the follow-up period, while in 5 patients there was evidence of metastases elsewhere.

Breast Neoplasms↗
PubMed1977

The role of mastectomy in locally advanced breast cancer.

The role of mastectomy in locally advanced breast cancer remains to be established. Experience at the Breast Clinic at the Provincial Hospital, Port Elizabeth, strongly suggests that mastectomy improves local control. The addition of mastectomy to a basic regimen of radiotherapy and adjuvant chemotherapy now forms the basis of a prospective clinical trial.

Adult↗
PubMedDate not supplied

Analysis of methadone and its primary metabolite in meconium.

Methods for analysis of methadone and its principal metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in meconium, based on fluorescence polarization immunoassay (FPIA) and high-performance liquid chromatography (HPLC) and diode array detection were developed. Meconium and urine samples of 16 neonates from 15 methadone-using mothers were analyzed. Because of the lower detection limit and the possibility of coanalyzing EDDP, meconium analysis with HPLC for detecting methadone use is very much preferable to FPIA. Identical results were obtained with HPLC analysis for both matrices: methadone or EDDP or both could be detected in the urine and meconium samples from 15 children. The amount of EDDP in meconium was much higher than the amount of methadone (ratio, 9.6). EDDP only was detected in eight of the meconium samples. A positive correlation was found between the methadone dose of the mothers and the methadone concentration in meconium, but not with the EDDP concentration in meconium.

Chromatography, High Pressure Liquid↗