Biomedical subjects
Publications and source records attributed to H Roos.
The lymph nodes of the stomachs taken from 31 sheep and 35 goats were described and measured. Compared with lymph nodes of cattle (Baum, 1912) marked differences were found regarding the position, number and presence of the nodes, as well as in regard to the lymphatic vessels leaving them. The results are discussed in the light of the decisions that may have to be made during meat inspection.
The variance-covariance method is employed at low doses and in radiation fields of low dose rates from an 241Am (4 nGy/s) and a 90Sr (300 nGy/s) source. The preliminary applications and results illustrate some of the potential of the method, and show that the dose average of lineal energy or energy imparted can be determined over a wide range of doses and dose rates. The dose averages obtained with the variance-covariance method in time-varying fields, for which the conventional variance method is not suitable, agree well with results obtained under the condition of constant dose rate. The results are compared to data obtained in terms of the conventional single-event measurements. The method has evident advantages, such as facility and speed of measurement.
The yield of his+ reversions in the Ames Salmonella tester strain TA2638 has been determined for 60Co gamma rays, 140 kV X rays, 5.4 keV characteristic X rays, 2.2 MeV protons, 3.1 MeV alpha particles, and 18 MeV/U Fe ions. Inactivation studies were performed with the same radiations. For both mutation and inactivation, the maximum effectiveness per unit absorbed dose was obtained for the characteristic X rays, which have a dose averaged linear energy transfer (LET) of roughly 10 keV/micron. The ratio of the effectiveness of this radiation to gamma rays was 2 for inactivation and about 1.4 for the his+ reversion. For both end points the effectiveness decreases substantially at high LET, i.e., for the alpha particles and the Fe ions. The composition of the bottom and the top agar was the one recommended by Maron and Ames [Mutat. Res. 113, 173-215 (1983)] for application in chemical mutagenicity tests. The experiments with the less penetrating radiations differed from the usual protocol by utilization of a technique of plating the bacteria on the surface of the top agar. As in an earlier study [Roos et al., Radiat. Res. 104, 102-108 (1985)] greatly enhanced yields of mutations, relative to the spontaneous reversion rate, were obtained in these experiments by performing the irradiations 6 h after plating, which differs from the conventional procedure to irradiate the bacteria shortly after plating.
The findings of Hill et al. (1984) on the greatly enhanced transformation frequencies at very low dose rates of fission neutrons induced us to perform an analogous study with alpha-particles at comparable dose rates. Transformation frequencies were determined with gamma-rays at high dose rate (0.5 Gy/min), and with alpha-particles at high (0.2 Gy/min) and at low dose rates (0.83-2.5 mGy/min) in the C3H 10T1/2 cell system. alpha-particles were substantially more effective than gamma-rays, both for cell inactivation and for neoplastic transformation at high and low dose rates. The relative biological effectiveness (RBE) for cell inactivation and for neoplastic transformation was of similar magnitude, and ranged from about 3 at an alpha-particle dose of 2 Gy to values of the order of 10 at 0.25 Gy. In contrast to the experiments of Hill et al. (1984) with fission neutrons, no increased transformation frequencies were observed when the alpha-particle dose was protracted over several hours.
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In the years 1974 to 1981, herniography was performed in 78 athletes with groin pain. The investigation comprised 101 painful groin sides in 23 athletes with bilateral symptoms. Before herniography, a hernia was palpated in only eight (7.9 percent) groins with pain. Hernias were found at herniography in 84.2 percent of the symptomatic groin sides and in 49.1 percent of the asymptomatic groin sides. Sixty-three hernia operations were performed. The herniographic and operative diagnoses corresponded well. Direct hernias dominated among the operated athletes, and were found in 55.6 percent of those below 30 years of age. Altogether 69.8 percent of the operated patients were cured by hernia repair and another 20.6 percent were improved. Tenoperiostitis of the adductor muscles was the most frequent diagnosis in those not cured by operation and among the nonoperated patients. Herniography was of great value in selecting those patients who needed a repair. A broad differential diagnostic approach when examining these patients is of the utmost importance.
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In human orthopedics the standard goniometer is used as an instrument to standardize joint measurements internationally. If some special rules are observed it can also be helpful in measuring and noting joint motions of animals. First of all one should know the specific "standing angles" and the definition of the basic planes for all joint motions and positions and one should also know that it is only possible to investigate passive mobility.
Gamma-ray-induced reversions in the Ames Salmonella tester strain TA2638 have been studied for their dependence on a number of experimental parameters. It is shown that exposure to ionizing radiations soon after plating is not the procedure that yields results which correspond to those obtained in the standard utilization of the test with chemical mutagens. The ability to detect mutants is improved by irradiation 6 hr after the beginning of the incubation of the plated bacteria. This procedure has the double advantage of a markedly increased ratio of radiation-induced to spontaneous revertants and of resulting in substantial insensitivity to fluctuations in the number of bacteria initially plated. The reversion-doubling dose so obtained is 1.3 Gy; i.e., it is sufficiently small to disregard inactivation of the bacteria.
In 22 patients with femoral neck fractures 99mTc-MDP scintimetry was performed before operation and again shortly after operation; in 17 of these patients the investigation was repeated after four months. Six patients with increased uptake in the femoral head before operation and eight with decreased uptake had similar results at the first postoperative investigation. Of eight patients with an intermediate uptake before operation, two showed increased and six decreased femoral head uptake after operation. It is concluded that for the patients in the group with intermediate femoral head uptake before operation, the operative procedure probably influenced the postoperative blood supply of the femoral head.
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