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Biomedical subjects

M Hanna

Publications and source records attributed to M Hanna.

85 records · Page 5Linked to original sources
PubMed1979

Wilms tumor, misdiagnosed preoperatively: a review of 19 National Wilms Tumor Study I cases.

This study establishes the difficulty in making specific diagnoses in children with retroperitoneal tumors when only excretory urograms are used in diagnosis. Complementary use of excretory urography and ultrasonography should make the number of preoperative errors less by separating cases of Wilms tumor from those with cystic disease. This investigation underscores the hazards inherent in the use of preoperative irradiation and chemotherapy, since some children with benign disease are likely to receive inappropriate therapy.

Child↗
PubMed1978

Isolated torsion of penis. Report of 6 cases.

Torsion of the penis as an isolated anomaly has rarely been reported. Six such cases seen in a pediatric urologic practice within a two and one-half-year span suggest that it is not as rare as has been hitherto suggested. The embryologic abnormality appears to be an isolated skin and dartos defect, since the torsion is completely remedied by simply freeing the penile shaft of its investing tissue. The ease of achieving a normal appearance would appear to justify its surgical correction.

Adolescent↗
PubMedDate not supplied

Zollinger-Ellison syndrome associated with a renal gastrinoma in a child.

Renal gastrinoma has not been previously reported. A 12-year-old boy with Zollinger-Ellison syndrome was found to have a renal tumor. No other tumor was detectable by imaging techniques, and selective venous sampling for gastrin showed a significant renal vein to vena cava gradient. Nephrectomy was performed, and examination of the tumor showed typical histologic features of an endocrine tumor. G cells were apparent by electron microscopy, and immunoperoxidase staining for gastrin, neuron-specific enolase, and chromogranin were positive. The gastrin content was unusually low for gastrinomas: 128 pg/g. Following nephrectomy, fasting gastrin and secretin stimulation testing were normal. Basal acidity was reduced by 60% but remained elevated at 39 mmol H +/h (hydrogen ion per hour). We speculate that renal gastrinoma may be characterized by uniquely poor gastrin storage and that curative resection of all gastrinoma tissue may not necessarily be associated with immediate complete suppression of hyperacidity.

Child↗
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↗