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Biomedical subjects

M Hofmann

Publications and source records attributed to M Hofmann.

At least 271 records · Page 15Linked to original sources
PubMed1981

[Changes of bone-perfusion in osteosynthesis of the femur with a marrow-nail (author's transl)].

The perfusion of the bone in the hind leg after osteosynthesis (nailing of the bone-marrow) was studied. In 11 shepherd dogs (bastards) an osteotomy of the femur was done; it was treated with a marrow-nail without boring the marrow-cavity. With the "tracer-microsphere"-method the perfusion of femur, tibia and talus of both hind legs was measured. Measurements were performed before and after surgery, in 10 dogs 2 weeks and in 8 dogs 6 weeks after surgery. Immediately after the operation the perfusion was reduced considerably in all the examined bones of the operated leg. Two weeks later the perfusion was increased in all bones of both hind limbs. In the cancellous bone of the femur the perfusion reached the original preoperative values after 6 weeks; in cortical bone a further increase of the perfusion was noted. This increase was most marked in the cortical bone of the operated femur; it was less in the cortical bone of the other bones.

Animals↗
PubMed1981

Stimulation in infancy facilitates interhemispheric communication in the rabbit.

Experimental rabbits were stimulated in infancy by being handled, while controls were undisturbed. After reaching adulthood, the animals were tested for activity in an open field with: (i) the right eye occluded; (ii) the left eye occluded; and (iii) neither eye occluded. For rabbits not stimulated in infancy, the correlation between activity scores for the left eye and right eye occlusion conditions was not significant (r = 0.115). In contrast, the correlation was highly significant for handled animals (r = 0.829). The results of the nonhandled group are consistent with other research which has failed to find interocular transfer of visual information, while the significant interhemispheric correlations within the handled group are consistent with prior findings obtained with rats. The results suggest that stimulation in infancy may act to facilitate the functional competence of the corpus callosum.

Animals↗
PubMed1980

Handling in infancy, taste aversion, and brain laterality in rats.

Rats were handled for the first 20 days of life or were not disturbed. When adults, they were trained to approach and drink from a bottle containing sweetened milk and were then given an injection of lithium chloride to induce a taste aversion conditioned emotional response. Others were injected with physiological saline. Rats within each of the treatment groups were then randomly assigned to 4 surgical procedures: removal of the right or left neocortex; sham surgery; or no surgery. Postoperatively, they were tested for retention of taste aversion by presenting the sweetened milk and recording the amount consumed. The initial consummatory behavior was very low (showing retention of the aversion) and increased over time. There were no differences in the reacquisition curves of the non-handled groups which had received lithium chloride. The curves of the handled groups did differ: thos with an intact right hemisphere (left neocortical lesion) had the lowest asymptote, followed by the group with an intact left brain, while those with intact whole brains consumed the greatest amount of milk. In the groups given an injection of physiological saline, those with a left hemisphere lesion consumed less milk than the other groups, regardless of their early handling experience. The data show: (1) that the rat's brain is lateralized, with the right hemisphere being preferentially involved in conditioned emotional behavior; and (2) that handling in infancy makes the left hemisphere less suceptible to conditioned fear.

Animals↗
PubMed1979

Interaction of sulfpride and ergot derivatives on rat brain DOPAC concentration and prolactin secretion in vivo.

Sulpiride, which differs from classical neuroleptics by not producing major extrapyramidal side effects, is a potent antiemetic agent and stimulates prolactin secretion in both laboratory animals and man. In parallel it increases dopamine synthesis in both striatum and nucleus accumbens. Bromocriptine and metergoline are two effective agents in suppressing prolactin release and postulated to stimulate dopamine receptors. The interactions of these two ergot derivatives with sulpiride have been investigated on prolactin release and on striatal and limbic DOPAC accumulation. Bromocriptine at all doses tested was able to suppress the increased in vivo prolactin secretion observed after sulpiride administration. Metergoline antagonized the sulpiride-induced prolactin increase only at low doses; on the contrary higher doses potentiated it. High concentrations of bromocriptine suppressed the sulpiride-induced increased of DOPAC levels in striatum and n. accumbens, while metergoline potentiated the sulpiride-induced accumulation of brain DOPAC.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1979

[The necessity of registration measurements in the construction of masticatory surfaces].

Model studies of denture forms with group contact and front canine guidance showed that a procedure for the reconstruction of grinding surfaces not directly involved in movement guidance, based on the mean values, can be accurate. The standard measures of registration for transference to a semiadjustable articulator are adequate for satisfactorily reducing vertical deviations to a clinically tolerable minimum in reconstruction guide planes.

Dental Articulators↗
PubMed1979

[The mandibular position and the masticatory surface complex in rehabilitations with total prostheses].

The construction principles for a complete denture were discussed in terms of the jaw relation and the masticatory surface complex with special reference to the conservation and preservation of the prosthetic support material. The habitual, neuromuscularly determined, position is recommended as a starting position of the mandible for the construction of this alignment; intraoral, central rod analysis of the support is helpful for the determination. When the lateral teeth are aligned, masticatory stability should be considered. The occluding surfaces therefore should be reduced, and the occlusal cusps determined according to the transversal interval of the crests for the maxilla and the mandible. In terms of the occlusion (articulation) concept, the biomechanical demands shold be determined on the basis of unobstructed sliding movements; a completely balanced occlusion seems to be the most advantageous in spite of certain disadvantages. The desired goal may be achieved with a unilaterally balanced occlusion. Based on previous experience, canine guidance as articulation concept has proved to be less suitable since symmetrical stress is unobtainable with at least one crest.

Biomechanical Phenomena↗
PubMed1979

[The so-called "Camper's" plane as a reference plane for the construction of artificial sets of teeth].

Various reference points given in the literature use Camper's plane as an analogous plane for the occlusal plane. The original assumption that both planes run parallel to each other could not be confirmed. The measured angular deviations between both planes do not differ appreciably, regardless of the reference point or the examination method. It therefore was suggested that the teeth be aligned according to the plane: arbitrary hinge axis point - subnasal (AG-SN plane). A re-evaluation of more than 100 subjects with complete dentition showed an average angular deviation of 3.87 degrees with the occlusal plane.

Cephalometry↗
PubMed1979

[The effect of the arrangement of the artificial sets of teeth on the physical stability of total protheses].

The effect of masticatory forces within and outside the stable stress-bearing areas of the complete upper denture on the pressure gradient and the flow of saliva into the space under the prosthesis were demonstrated with standardized tests. It was shown that masticatory stress within the stable area led to a continual increase in pressure in the space under the prosthesis. Masticatory force outside the stable area led to a decrease in pressure and an equalization of pressure in this space as well as dislocation and tilting of the complete denture. Due to masticatory force outside the stable area, the shape of the ridge influences the stability of the complete denture.

Dental Impression Technique↗
PubMed1979

[Parodontoplethysmography. A method of objective evaluation of the course of progressive scleroderma].

Parodontoplethysmography was repeatedly performed in seven patients with systemic sclerosis over a period of six years. The data obtained exactly correlated to improvement or deterioration in the patients' condition. Regular parodontoplethysmography is recommended in order to observe the course of the disease more objectively. Some of the examined patients roentgenographically showed a widening of the periodontal space, a typical feature of systemic sclerosis.

Adult↗