Biomedical subjects
Publications and source records attributed to H Martin.
Ultrasonic versus hand-powered K type files were compared for their ability to remove dentin from a standardized canal. The ultrasonic energized file removed a significantly greater amount of dentin in a fixed time period.
Diamond endodontic files and K-type files were compared for their ability to remove dentin when powered both by hand and by ultrasound. The diamond files were significantly superior dentin-removing instruments, especially when energized by ultrasound.
We studied the metabolic turnover of the major apoproteins of pulmonary surfactant from rat lung and compared it with similar studies on the metabolism of dipalmitoyl phosphatidylcholine (DPPC). At varying times after the injection of tritiated leucine or tritiated palmitate we isolated the alveolar cells and alveolar fluid and measured the incorporation of the radioactive leucine into the 35,000-dalton (apoprotein A) and 10,000-dalton (apoprotein B) apoproteins of surfactant and of the radioactive palmitate into DPPC. Maximum labeling of apoprotein A in type II cells occurred within 1 h after injection of the precursor and declined in the next 19 h. The labeling of intracellular DPPC followed the same time course. The labeling of apoprotein B in type II cells was low, and the change of its labeling with time was not consistent with its being secreted by these cells. Both proteins were labeled in alveolar fluid and in alveolar macrophages. The results indicate that apoprotein A is synthesized by type II cells and is probably secreted as part of the surfactant complex. Apoprotein B is not secreted by type II cells with the same time course as apoprotein A or the lipids of surfactant, but our results do not define its origin or physiological purpose.
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After intraperitoneal application of 14C-orotic acid the tracer distribution and the labelling of total RNA in different organs of two groups of Wistar rats (5 and 22,5 months old) were represented. After 60 min 2/3 of tracer were found in liver and kidney. The uptake by liver of old animals is decreased significantly. The interactions between the tracer distribution in the organism, the time related uptake by the organs, the organ function (influenced by methimazol) and the specific activity of RNA were represented. From the results the conclusion is drawn that the comparison of the specific activities of total RNA alone--especially in comparison of young with old animals--is not sufficient for the examination of RNA synthesis.
30 autopsy cases of gliomas (5 fusiform glioblastomas, 5 multiform glioblastomas, 5 fibrillary astrocytomas, 5 protoplasmic astrocytomas, 5 oligodendrogliomas, 5 spongioblastomas) were studied by means of morphometry. 7 parameters (volume and area parameters of tumor vessels and of tumor cell nuclei, mitoses) were tested for the ascertainament of useful quantitative criteria for the objective differentiation of the gliomas. 210 statistical comparisons were carried out. Significant differences were observed in 32 of them. It could be demonstrated that the parameters of the tumor cell nuclei are most useful in the differentiation of the gliomas. Significant differences do not exist between fusiform glioblastoma--multiform glioblastoma, fusiform glioblastoma--oligodendroglioma, fibrillary and protoplasmic astrocytoma--spongioblastoma.
The hormonal uptake, binding and responsiveness are decreased with few exceptions in the target organs of old animals. Qualitative changes of chromatin and changed receptor concentration and affinity are considered as causes.
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There are many hypotheses about the biological aging. Some error and programme hypotheses are explained and compared with another by examples. The action of stochastic and genetic factors is acknowledged generally, but there are different opinions on the question about a genetic "programme". At the same time there is an effort to integrate some alternative conceptions. By increasing appreciation of evolutional aspects too the interest are pointed out to biological longevity assurance mechanisms and their importance for the maximum lifespan of species or individuals.
Under the influence of stress the function of hypothalamic-pituitary system seems to show aging changes, whereas the adrenocortical function is not changed in spite of degenerative morphological changes in aging. By the performance and interpretation of experiments it is necessary to pay attention to the different reaction of young and old animals.
The mass development of heart ventricle (right and left with septum) was investigated with histologic-morphometric methods on rats from 1...14 days of live. The increase (twice) of myocard area is caused by increase of myocards of the left ventricle. Growth is the result of hyperplasie, in the second week it is the result of hypertrophy of heart muscle cells. The number of interstitiell cells enlarges to more than once. The perinatal change of circulation is the decisive factor for postnatal heart growth.
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