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Biomedical subjects

B Zimmermann

Publications and source records attributed to B Zimmermann.

At least 145 records · Page 8Linked to original sources
PubMed1980

Lung deposition and clearance of cadmium in rats exposed by inhalation or by intratracheal instillation.

115mCdCl2 was nebulized by a jet nebulizer, yielding an aerosol concentration of Cd of 660 ng/l. Rats were exposed nose only for 1 h. For the instillation study 115mCdCl2 was instilled intracheally, 8 microgram in 0.3 ml NaCl. Rats of both studies were serially sacrificed from day 0-100, and the lung activity was counted. The results showed a bi-exponential clearance pattern in both studies, where the long clearance gave half lives of 61 d (inhalation) and 66 d (instillation), respectively. The short term clearance half lives were 1.1 d (inhalation) and 0.7 d (instillation). About half of the deposited Cd is cleared in both studies in the fast phase. After inhalation, 16% more Cd was deposited in the alveolar area as compared to instillation. It was found that on the second day after instillation of CdCl2 only 2% could be lavaged out of the lungs, suggesting a protein binding of Cd in the lung.

Aerosols↗
PubMed1980

Development of ferret limb buds in organ culture.

The forelimb bud explants from ferret embryos at days 20, 21, 22, 23 and 24 of gestation were cultured in a Trowell organ culture system. Satisfactory differentiation of the limb bud skeleton was achieved with limbs from embryos explanted at 22 days of gestation (up to 50 somites). Limb buds explanted at 20 and 21 days had poorly differentiated distal segments while those explanted at 23 and 24 days of pregnancy provided less information because chondrogenesis was already under way at the beginning of culture. Thus we conclude that the optimal time for culture of ferret limb buds is at 22 days of gestation. The level of differentiation corresponded to that obtained with mouse limb buds from 11 to 12 day embryos (40-43 somites). The time taken to achieve this level of differentiation in the ferret was 18 days compared with 6 days in the mouse.

Animals↗
PubMed1979

[Mortality due to carcinoma of the stomach between 1954 and 1974. Changes in France (author's transl)].

A study of changes in mortality due to carcinoma of the stomach in France between 1954 and 1974 was undertaken on the basis of probable levels standardised on the French population in 1968. There was a marked fall in this mortality for both sexes. In the male, the initial level in 1954 was 54.8/100 000 and the decrease was of the order of 1.35 deaths per 100 000 per year, i.e. an annual fall of -3.21%. This phenomenon was more marked during the second period (1965--1974): - 3.88%, than during the first period (1954--1963: - 2.38%. In the female, with an initial mortality rate of 31.25/100 000, the annual decrease was 31.25/100 000, i.e. an annual fall of - 3.49%. This fall was - 3.09% for the first ten year period and - 4.80% for the second period. Thus in France, in common with many other countries, there has been a marked decrease in mortality due to carcinoma of the stomach, for both sexes, and this phenomenon became progressively more notable during the period of the study.

Female↗
PubMed1978

Release of glycolytic enzymes from cultivated tumor cells.

Several types of cultured cells release glycolytic enzymes into their suspending medium. This effect is most obvious with tumor cells, especially with their ascites forms. Erythrocytes do not release glycolytic enzymes. The total extracellular phosphoglucose isomerase activity consists of two components. One part is dissolved in the medium, the other one is sedimentable at 150 X g together with the cells. The latter seems to be localized at the cell surface. At densities of about 10(6) cells/ml maximum activity in the medium is reached within 5--10 min. After that no further release of enzyme activity can be observed. Serum reduces the rate of enzyme release considerably. This effect can be reversed by washing with protein free media. Treatment with trypsin leads to high extracellular phosphoglucose isomerase activities of the cells which originally show low external enzyme activity. Erythrocytes do not show any effect with trypsin, ascites tumor cells do not alter their high extracellular enzyme activity. At a density of 10(5) cells/ml, Yoshida acites tumor cells, cultured in vitro, release about 12% of originally intracellular phosphoglucose isomerase activity by 5 elutions with fresh medium. The process of enzyme release shows a certain selectivity in respect to different glycolytic enzymes. Aldolase exhibits the highest activity in the medium in relation to its homogenate activity.

Animals↗
PubMed1978

The development of alkaline phosphatase activity in limb buds of mouse embryos in vitro and its relation to chondrogenesis.

The development of alkaline phosphatase (aPh) activity and chondrogenesis were studied in the limb buds of mouse embryos (day 11 p.c.) that had been grown in an organ culture. During a 12-day culture period an increase in aPh activity to more than 40 mU/limb bud was measured from day 2 in vitro onward. Depending on the time of application, aPh formation can be inhibited by certain substances. Cytosine-arabinoside inhibits aPh activity when the substance is added on day 2, 3, or 4. Chondrogenesis, on the other hand, is affected on days 1, 2, and 3 and to a lesser degree on day 4. Actinomycin D interferes with aPh activity after its addition on day 1, 2, 3, or 4. Chondrogenesis is only inhibited when the drug is applied on the 1st, 2nd, or to a lesser degree on the 3rd day. Cycloheximide inhibits aPh formation on all days of treatment, but to a lesser degree on days 5 and 6; chondrogenesis is most influenced on days 2, 3, and 4. On day 6 of the culture period, aPh activity can be demonstrated histochemically only in the region of humerus and proximal parts of radius and ulna. Alterations in the distal cartilage skeleton, therefore, do not influence the activity data. A prerequisite for an increase in aPh activity is cartilage growth in the proximal part of the limb buds and subsequent induction of a perichondral cell population to proliferation and differentiation.

Alkaline Phosphatase↗
PubMed1976

Influence of cell density of nuclear size in monolayer cells from embryonic mouse brains.

Studies were carried out on the nuclear size of embryonic mouse brain monolayer cells at various cell densities. The variation in cell density resulted from different initial cell numbers. The nuclear area was measured area-analytically with the Quantimet, the determination of cell population was measured linear-analytically using the Digiscan. Nuclear size remains constant in a cell culture of 10(4) up to 8.3 X 10(4) cells ml, which corresponds to a cell density of about 25-160 cells/unit. A significant diminution in mean nuclear size of the cell nucleus occurs in the case of increased cell densities of 215 and 277 cells/unit, corresponding to a cell culture of 2.5 X 10(5) AND 7.3 X 10(5) cells ml. This diminution may be connected with the accumulation of G1 cell nuclei in cultures with contact-dependent growth inhibition.

Animals↗
PubMed1976

[Linear- and Areal-analytical results of the karyometric studies on monolayer cultures and the influence of actinomycin (author's transl)].

Actinomycin D (AMD) inhibits the RNA-synthesis by intercalating with the DNA-helix. In monolayer culture of embryonic mouse brain cells in the 8th passage the cell nuclei were demonstrated with the Feulgen-reaction and quantitatively-morphometrically evaluated following a 48 h intoxication with AMD (0.001; 0.01; 0.1 mug/ml). The mean value of nuclear area calculated from single measurements with the Quantimet 720 is significantly larger when compared to the controls at a dose of 0.01 mug AMD/ml. At 0.1 mug AMD/ml ca. 30% of the cell nuclei are pyknotic; the non-pyknotic nuclei are enlarged significantly by appr. 20%. The linear-analytic results using a Digiscan show no enlargement of tendon length, on the contrary, at 0.1 mug AMD/ml a significant diminution versus the controls can be seen. This resutls from the pyknotic cell nuclei which are also measured in this case no single measurements were carried out. The determination of cell density using a Digiscan shows a diminution of cell number by 19, 31 or 68% dependent upon AMD-concentration.

Animals↗
PubMed1975

[Measurement of nuclear size in cells from embryonic mouse brain in monolayer culture using automatic image analysers].

Size analyses and size classifications were made of the nuclei of embryonal mouse brain cells in monolayer culture. Measurements were made by surface analysis, using the Quantimet (1,299 nuclei), and linear analysis, using the Digiscan (1,887 nuclei). Despite the different methods of measurement and different logarithmic classification, similar distribution curves were obtained, approaching the Gaussian normal distribution. The methodical problems of karyometry as well as the problems of statistical data processing are discussed.

Animals↗
PubMed1975

Change of nuclear size in monolayer cells from embryonic mouse brain under the influence of cytosine-arabinoside.

The influence of cytosine-arabinoside (ara-C) on the nuclear size of monolayer cells from mouse brains were studied by quantitative analysis with the Quantimet (area measurement) and linear analysis with the Digiscan. Ara C (0,1; 1,0; 10,0 mug/ml) causes a significant nuclear enlargement, depending on the dose of 16%, 30% and 35% respectively and at the same time a decrease in cell density and an inhibition of mitotic activity. The size-distribution graph is altered by ara-C: the graph flattens and widens at the base. Moreover, in the case of 10,0 mug ara-C/ml a pronounced graph shoulder is visible in the small nuclear size region which can be interpreted as a slight accumulation of small nuclei. The nuclear enlargement is possibly due to an accumulation of shortchain polynucleotides.

Animals↗