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Biomedical subjects

B Diez

Publications and source records attributed to B Diez.

26 records · Page 2Linked to original sources
PubMed1988

Glucokinase-deficient mutant of Penicillium chrysogenum is derepressed in glucose catabolite regulation of both beta-galactosidase and penicillin biosynthesis.

One glucokinase-deficient mutant (glk1) of Penicillium chrysogenum AS-P-78 was isolated after germ tube-emitting spores were mutated with nitrosoguanidine and selected for growth on lactose-containing medium in the presence of inhibitory concentrations of D-2-deoxyglucose (3 mM). Penicillin biosynthesis was greatly reduced (55%) in D-glucose-grown cultures of the parental strain, but this sugar had no repressive effect on the rate of penicillin biosynthesis in the mutant glk1. This mutant was deficient in ATP-dependent glucokinase and showed a greatly reduced uptake of D-glucose. The parental strain P. chrysogenum AS-P-78 showed in vitro ATP-dependent phosphorylating activities of D-glucose, D-2-deoxyglucose, and D-galactose. The glk1 mutant was deficient in the in vitro phosphorylation of D-glucose and D-2-deoxyglucose but retained a normal D-galactose-phosphorylating activity. D-Glucose repressed both beta-galactosidase and isopenicillin-N-synthase but not acyl coenzyme A:6-aminopenicillanic acid acyltransferase in the parental strain. The glucokinase-deficient mutant was simultaneously derepressed in carbon catabolite regulation of beta-galactosidase and isopenicillin-N-synthase, suggesting that a common regulatory mechanism is involved in carbon catabolite regulation of both sugar utilization and penicillin biosynthesis.

Carbon↗
PubMed1987

Long-term endocrine sequelae after surgery, radiotherapy, and chemotherapy in children with medulloblastoma.

Thirteen children with medulloblastoma, were studied after 2 to 62 months off radiotherapy and chemotherapy with methotrexate and BCNU. Ages at time of study ranged from 2.3 to 15.7 years. Eleven patients, followed for a mean of 22 months, showed a significant decrease of height score, whereas nine patients had deficient growth hormone (GH) response to provocative tests. Clinical pubertal progression was normal in all patients, and three of five girls with advanced pubertal development had menarche. No evidences of gonadotropin disturbances were found in five patients whereas seven had raised basal follicle-stimulating hormone (FSH) level or FSH response to luteinizing hormone-releasing hormone (LH-RH). Abnormalities in thyrotrophin (TSH) secretion were found in 9 of 13 patients. This study shows that poor growth and GH deficiency were frequent in our patients. The high frequency of thyroid disturbances observed point out the need of evaluating thyroid function for adequate replacement therapy. Perhaps modification of adjuvant chemotherapy in the future can diminish drug-induced gonadal damage.

Adolescent↗
PubMed1986

Paratesticular rhabdomyosarcoma in children.

The clinicopathological features of 10 children with paratesticular rhabdomyosarcoma treated between 1965 and 1984 are reviewed. Of the patients 9 had embryonal rhabdomyosarcoma and 1 was pleomorphic. Median age was 4 years (range 2 to 11 years). Staging was based on clinical findings, chest x-ray, lymphoangiography, computerized tomography and histological studies. The disease was stage I in 5 patients, stage II in 2 and stage IV in 3. Treatment included radical orchiectomy in all patients, chemotherapy in 8 and lumboaortic radiotherapy in 5. No retroperitoneal node lymphadenectomy was performed. Of the 10 children 7 are free of disease after 2 to 19 years (median 7 years) of followup, including all of those with stages I and II disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Primary rhabdomyosarcoma of brain and cerebellum. Report of four cases in infants: an immunohistochemical study.

Tumors of the central nervous system (CNS) composed of pure mesenchymal derivatives with both embryonal and mature striated muscle cells devoid of neuroblastic elements should be considered rhabdomyosarcomas. Some 13 cases have been reported, and here we study four additional cases in infancy under 3 years of age which represent 0.82% of 483 intracranial tumors studied by us at the Children's Hospital in the last 12 years. Two cases were localized in the temporal lobes, and two were in the cerebellar vermis. All of them were typical embryonal rhabdomyosarcomas at various stages of differentiation including undifferentiated mesenchymal cells, embryonal cells, and rhabdomyoblasts. Tumor cells achieved a higher degree of differentiation in the cerebellum, as shown by readily detectable immature muscle fibers which were consistently absent in tumors involving the brain. Myoglobin [peroxidase-antiperoxidase (PAP) technique] was positive throughout in rhabdomyoblasts and in immature muscle cells, whereas glial fibrillary acidic protein was negative in all four tumors. In spite of the well differentiated appearance of the cerebellar tumors, their behavior was highly malignant with extensive infiltration of brainstem leptomeninges in one case, and all patients survived for only a short time after surgery. These tumors may be observed in the midline structures of the posterior fossa and in the brain, but we suspect their true incidence might be higher if immunohistochemical techniques were applied.

Brain Neoplasms↗
PubMed1984

Comparison of two consecutive trials for treatment of childhood non-Hodgkin's lymphoma.

Two consecutive trials for the treatment of childhood non-Hodgkin's lymphoma were evaluated, carried out by the same cooperative groups. Group A: From June, 1973 to December, 1975, 50 evaluable patients under 16 years of age participated in a study that included vincristine and prednisone plus surgery and/or radiotherapy as induction. This was followed by 2400 rad of cranial radiotherapy plus 5 doses of intrathecal methotrexate-dexamethasone and anti-leukemia (6-mercaptopurine, methotrexate, cyclophosphamide) or anti-lymphoma (cyclophosphamide, vincristine, procarbazine, and prednisone) maintenance treatment. Group B: From January, 1976 to December, 1980, 55 evaluable patients participated in a consecutive study that added Adriamycin (doxorubicin) and cyclophosphamide to the former induction regimen. Central nervous system (CNS) prevention was performed with 5 doses of intrathecal methotrexate-dexamethasone. Maintenance treatment was the same. Prognostic factors as stage and primary site were comparable in both groups. A total of 33 (66%) of 50 children of Group A and 48 (87%) of 55 children of Group B achieved complete remission (P less than 0.005). Disease-free survival at 60 months was 27% in Group A and 49% in Group B; for Stage I-II, 30% in Group A and 85% in Group B (P less than 0.025); for Stage III-IV 28% in Group A and 36% in Group B (not significant). In Group A, 9.1% and in Group B, 8.3% had primary CNS relapse. Both maintenance schedules had the same relapse rate. It was concluded that: (1) the addition of Adriamycin and cyclophosphamide to vincristine-prednisone in Group B produces a higher rate of complete remission in Stage III-IV, a higher rate of disease-free survival in Stage I-II, and a higher survival rate in all stages; (2) CNS prevention with intrathecal methotrexate-dexamethasone is equally effective as cranial radiation plus intrathecal methotrexate-dexamethasone; and (3) anti-leukemia and anti-lymphoma maintenance are equally effective in the context of this study.

Adolescent↗