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Biomedical subjects

E H Betz

Publications and source records attributed to E H Betz.

At least 19 recordsLinked to original sources
PubMed1985

Target cells and thymus microenvironment in the pathogenesis of thymic lymphomas in C57BL/Ka mice.

In C57BL/Ka mice, the induction of thymic lymphomas either by inoculation of radiation leukemia virus (RadLV) or by a split dose irradiation requires complex cellular events: Target cells are found among the population of thymic subcapsular blast cells, or, alternatively, of marrow or spleen prothymocytes; Progression of target cells to lymphoma growth requires a multi-step process, which occurs only within thymic microenvironment; Target cells are rapidly induced as "preleukemic" cells; After inoculation of RadLV, the initial events occur when target cells are in close association with cells of a specialized component of thymic epithelium, i.e., the so-called "nurse cells"; The leukemogenic agents induce damages to the thymic microenvironment itself; Lymphoma prevention by marrow grafting after irradiation results from mechanisms still unknown which inhibit the progression of "preleukemic" cells to neoplastic growth.

Animals↗
PubMed1983

Promotion mechanism of phenobarbital and partial hepatectomy in DENA hepatocarcinogenesis cell kinetics effect.

Diethylnitrosamine (DENA, 10 mg kg-1 per day) was fed to rats for 2, 4 and 6 weeks. One week after the cessation of DENA, animals were submitted either to partial hepatectomy or to phenobarbital administration. Partial hepatectomy did not promote neoplastic transformation, except after a 6-week DENA treatment. A minimum of phenobarbital was required to reach a significant promoting effect in DENA carcinogenesis. A too-limited treatment was ineffectual but could be compensated for by prolonged DENA administration. The phenobarbital treatment became unnecessary when neoplastic nodules were present. Phenobarbital continuously given after the carcinogen administration promoted neoplastic transformation even after a subcarcinogenic DENA treatment (2 weeks). It accelerated the pathological evolution and increased the tumour incidence. In these conditions, phenobarbital increased the proliferation advantage of preneoplastic cells over normal cells. In the different experimental modalities, the promoting effect was associated with the induction of chronic cell proliferation, the inhibition of the rapid response to the 2/3 partial hepatectomy and the mitotic circadian rhythm normally present during liver regeneration. It is concluded that the promotion mechanism could consist in disturbing the mitotic control in order to maintain, for a long time, a chronic low level of cell proliferation permitting the selective growth of preneoplastic cells and their subsequent transformation.

Animals↗
PubMed1981

Proliferation of preneoplastic lesions after discontinuation of chronic DEN feeding in the development of hepatomas in rat.

Diethylnitrosamine (DEN, 10 mg/kg/day) was fed to rats for 2, 4 and 6 weeks. At different times after feeding with DEN was stopped, growth of preneoplastic lesions has been correlated with pathological evolution (preneoplastic foci, neoplastic nodules and hepatomas). The proliferating fraction in the foci, the cell content, and relative volume of foci increase as a function of the duration of the treatment. The proliferating fraction increases evenly throughout the liver, but, in all experimental modalities, preneoplastic cells show a proliferative advantage over the phenotypically normal tissue. In each experimental group, the proliferative rate correlates with the pathological evolution. After 2 weeks of DEN feeding the growth activity of foci remains very low, and neoplastic nodules are not detectable until the median time of death (14 months). After 4 and 6 weeks, a critical size of the foci is reached, corresponding to the neoplastic transformation, and an increased labelling index is triggered in the lesions and in the phenotypically normal tissue. It is speculated that the "growth pressure" induced by the first carcinogen treatment, associated with the subsequent disturbance of the mitotic control regulation, may be implicated in the process of malignant transformation of preneoplastic lesions.

Animals↗
PubMed1980

Spontaneous immunoglomerulonephritis in Wistar rats.

A strain of rats bred at the Nuclear Study Center of Mol (C.E.N.) develops a nephropathy characterized by granular deposition of immunoglobulin and complement in the renal glomeruli and tubules. We have attempted to specify the complement activation pathways (classical or alternate) in this disease by looking for their initial components (C1q, C3 and C4) in tissue lesions. The immunohistologic and histologic course of the disease has been followed in male and female rats. Immunohistologic results show that glomerular and tubular injury in CEN Wistar rats may be mediated by the classical pathway of complement activation. Histologic data demonstrate that the tubular, glomerular, and interstitial lesions appear in both sexes, but are more extensive and develop earlier in male rats. The lipopigments found in tubular cells suggest a lysosomal dysfunction which might contribute to the progress of the disease.

Animals↗
PubMed1979

Effects of discontinuation of chronic feeding of diethylnitrosamine on the development of hepatomas in adult rats.

Diethylnitrosamine (DENA) at 10 mg/kg was fed to adult rats either continuously or for periods ranging from 1 to 10 weeks. Survival correlated inversely with the duration of carcinogen feeding. Less than 4 weeks of DENA feeding produced only preneoplastic foci that persisted indefinitely; 4 weeks were found to be necessary for the transformation of preneoplastic lesions into liver cancers; after 6 weeks, the incidence of hepatomas was 100%. The process of liver cancerization appeared to be identical whether DENA was fed for 8 weeks or continuously up to the time of death. These results are discussed in the light of the evolution of the homoeostatic control of liver-cell division during DENA feeding, in order to distinguish the different successive roles played by the carcinogen.

Animals↗
PubMed1978

[Breast check-up and high risk factors in breast cancer screening (author's transl)].

Between 1966 and 1977, 142 breast cancers have been discovered in 85 250 women among 120,000 routine clinical examinations. Comparison between the information given by mammography alone compared with the panel of specialized techniques (cytology, thermography, mammography, echography) shows superiority for the latter. Complete breast check-ups have doubled the percentage of cancers discovered in the women that were examined (from 0,8% to 1,8%). A family history of breast cancer does not help in the discovery of cancer, except in cases of mammary changes noticed by the patient herself. However, these women have to be checked regularly, because the number of cancers diagnosed does not decrease at subsequent visits. The generalized practice of self-examination and of less mutilating treatment should encourage patients to consult earlier, as they have less fear that mutilating surgery will be performed.

Adult↗
PubMed1977

Ultrastructural autoradiographic study of blast cells in the mouse thymus. Interest for radioleukemia research.

Ultrastructural autoradiographic studies of mouse thymic blast cells after H3 Tdr injection show that their fine nuclear structure is related to their position in the cell cycle. The variations in the composition of the subcapsular blast cell population during radiation-induced leukemogenesis indicate kinetic changes in thymic lymphopoiesis, which are probably due to the oncogenic process.

Animals↗