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Biomedical subjects

R Graf

Publications and source records attributed to R Graf.

At least 253 records · Page 14Linked to original sources
PubMed1980

The diagnosis of congenital hip-joint dislocation by the ultrasonic Combound treatment.

Due to poor penetration of bone, ultrasonic techniques have not been popular in orthropedic procedures. Since they are non-invasive and are not associated with a radiation hazard, their application in the diagnosis of congenital hip-joint dislocations merits investigation. Methods are presented in Part I which should enable the experienced investigator to make the diagnosis and avoid flash interpretations. In Part II, the practical results of these techniques over an 18 month period are presented and discussed. The small size of the object under examination and the, in general, poor resolving power of ultrasonoscopes constitute the major difficulties encountered when using ultrasonic diagnostic devices. The fact that these methods are harmless to the patient, economical, simple to perform, and noninvasive, make them attractive diagnostic tools for screening infant hip-joints congenital luxations.

Child, Preschool↗
PubMed1980

Diurnal changes of thermoregulatory functions in pigeons. I. Effector mechanisms.

In pigeons, we studied the diurnal variation of body temperatures and its dependence on the diurnal variations of shivering, vasomotor activity and panting in light-dark (LSD) - conditions (12:12 h, 100:1 Lux) and in different, but for at least 24 h constant ambient temperatures. In low ambient temperatures (below thermoneutrality) shivering was reduced shortly after lights off (early dark phase), and it increased again some hours before lights on (late dark phase); the lower the ambient temperature, the larger the reduction of shivering and the shorter the time of reduction. Within thermoneutrality, the decrease of Tb in the early dark phase was associated with an increase of foot skin temperature, probably due to vasodilatation. Later-on foot skin temperature decreased again (vasoconstriction). The feet remained constricted even in the late dark phase, when Tb already increased. At higher ambient temperature (above thermoneutrality) vasodilatation persisted all over the 24 h, while in these conditions respiratory rate increased significantly after lights off. The described diurnal variations of thermoregulatory effector mechanisms are in agreement with the concept of an active adjustment of the body temperature rhythm.

Animals↗
PubMed1980

Diurnal changes of thermoregulatory functions in pigeons. II. Spinal thermosensitivity.

In pigeons there exists a pronounced day-night variation of deep body temperature with a maximum at day and a minimum at night. To investigate a possible influence of spinal cord thermosensitivity in generating the body temperature rhythm, we studied the relationship between the experimentally changed spinal temperature and either heat production or panting, respectively. The experiments were performed in LD 12:12h and at constant ambient temperatures. At an ambient temperature of 25 degrees C, the responses to spinal cooling are reduced during the dark phase. The spinal temperature theshold for activating heat production is about 2 degrees C lower during night, whereas the gain of the metabolic response to spinal cooling is nearly unchanged. The lower ambient temperature, the greater are the heat production responses during the dark phase in relation to those during the light phase. Warming the spinal cord to the same amount leads to different responses of respiration rate during day and night, too. The temperature threshold for thermal panting is lowered during the dark phase similarly to the lowered threshold for heat production responses. The described diurnal variations of the responses to spinal cord warming and cooling support the hypothesis of an involvement of spinal thermosensitivity in the generation of daily body temperature fluctuations.

Animals↗
PubMed1980

Potentiation of insulin secretion to nonglucose stimuli in normal man by tolbutamide.

To determine how sulfonylureas affect beta cell function, insulin release in response to isoproterenol and arginine was assessed in 32 normal subjects before and during a tolbutamide infusion. When the plasma glucose was allowed to decrease during tolbutamide, the acute insulin response (AIR) to isoproterenol was not changed (delta AIR = 4 +/- 8 MicroU/ml, mean +/- SEM, n = 8,p = NS) and was enhanced slightly for arginine (delta AIR = +61 +/- 26 microU/ml, n = 6, p less than 0.05). When plasma glucose levels were maintained by means of a concomitant variable glucose infusion during tolbutamide, the insulin responses to both isoproterenol and arginine were enhanced (isoproterenol: delta AIR = +55 +/- 15 microU/ml, n = 6, p less than 0.001; arginine: delta AIR = +137 +/- 34 microU/ml, n = 8, p less than 0.001). Regression analysis demonstrated a linear relationship between change in the prestimulus glucose level and the change in the AIR to isoproterenol during tolbutamide (r = 0.66, n = 14, p less than 0.02). Since the slope of his relationship is not significantly different from a similar relationship in the absence of tolbutamide, the potentiating effect of tolbutamide is an amplification of an established physiologic relationship. We conclude that tolbutamide augments the insulin response to nonglucose stimuli. However, this potentiating effect of tolbutamide may be masked by a decrease in the prestimulus glucose level.

Arginine↗
PubMed1979

Ultrastructural and histochemical investigation of the terminal capillaries in the spleen of the carp (Cyprinus carpio L.).

In the spleen of the carp arterial capillaries of a highly differentiated structure have been studied by light and electron microscopy. These capillaries share various structural characteristics with the sheathed capillaries (ellipsoids of Schweigger-Seidel) of higher vertebrates. The long arterial capillaries of the carp spleen are provided with cuboidal endothelial cells containing filaments approximately 7 nm in diameter. There is no basal lamina. The endothelial cells form various types of cell junctions, but there are also extensive areas without any junctions. Here, a free passage is possible between the capillary lumen and the subendothelial space. The capillaries possess a single-layered sheath of macrophages. Characteristically, the sheath macrophages posses long and slender cell processes forming a loose framework, the meshes of which are filled with lymphocytes and spindle cells. The sheath macrophages show a zone of ectoplasm rich in filaments. The also contain numerous phagolysosomes rich in hydrolytic enzymes, as identified histochemically. The sheath is sharply limited against the pulp by a thick layer of collagen fibers.

Acid Phosphatase↗
PubMed1979

Cyclic and non-cyclic variations of spinal cord temperature related with temperature regulation in pigeons.

1. The temperature of the spinal cord (Tvc) was measured in unanaesthetized pigeons at different ambient temperatures (Ta). 2. In short-term experiments spontaneous or noncyclic variations of Tvc at constant (20 and 10 degrees C) and changing Ta were correlated with the amplitude of the electromyogram EMG) which indicates shivering, i.e., heat production. At constant Ta no unequivocal correlation between Tvc (and also Tskin) and EMG was found. During ambient cooling there was often an increase of Tvc which resulted in a positive correlation whereas there was a negative correlation to Tskin. 3. In long-term experiments (24h, LD 12:12Y cyclic variations of Tvc were measured at different Ta and ocrrelated with O2-consumption, i.e., heat production. As with body temperature Tvc was lowered during the dark phase of the diurnal cycle. In the light phase both Tvc and heat production increased with decreasing Ta which results in a positive correlation. In the dark phase there was a smaller increase in heat production but a decrease in Tvc, i.e., a negative correlation. 4. The results show that natural variations of Tvc are often positively ocrrelated with heat production. This is in contrast to experimental changes of Tvc where a clear negative correlation to heat production can be observed.

Animals↗
PubMed1976

[On the endogenous peroxidase in the spleen of swine (author's transl)].

We studied the distribution of endogenous peroxidase in the spleen of swine by modifications of the Graham and Karnovsky diaminobenzidine procedure. There is a peroxidatic activity in the majority of the ellipsoid cells (cells of the sheathed capillaries of Schweigger-Seidel), which is localized in the endoplasmic reticulum and the perinuclear cisterna. This staining is inhibited completely by aminotriazole and is rapidly destroyed even by low concentratoins of glutaraldehyde. Furthermore, the reaction is abolished after boiling of tissue sections or in the absence of H2O2. The macrophages of the red pulp and a minority of the ellipsoid cells are peroxidase negative. Our results are discussed in respect to some recent studies on the system of mononuclear phagocytes. It is suggested, that the enzyme active ellipsoid cells represent a special form of macrophages, enzyme histochemically related to Kupffer cells and resident peritoneal macrophages. The enzyme negative cells of the ellipsoids are probably fibroblasts.

3,3'-Diaminobenzidine↗