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Biomedical subjects

A Nagel

Publications and source records attributed to A Nagel.

At least 37 records · Page 2Linked to original sources
PubMed1993

The clinical significance of the nutrient artery.

The nutrient foramina of 10 dry cadaveric specimens of human radius, ulna, humerus, femur, and tibia are described. The point of nutrient artery entrance relative to bony surface and distance from proximal articular margins are recorded. The relative risks for intraoperative injury to the nutrient artery during exposure and placement of internal fixation devices in these five long bones are described. The clinical relevance of avoiding injury to the nutrient artery and further compromising existing osseous injury is discussed. Suggestions regarding placement of internal fixation devices are offered.

Arteries↗
PubMed1991

Metabolic, respiratory and cardiac activity in the shrew Crocidura russula.

Oxygen consumption, respiratory rate, heart rate and body temperature of resting common white-toothed shrews (Crocidura russula, mean = 11.4 g), have been determined at ambient temperatures (Ta) between 0 and 37 degrees C. Mean basal oxygen consumption (Ta = 30 degrees C, Tb = 35.4 degrees C) was 2.3 ml.g-1.h-1 and was about 12% above the value expected on the basis of the allometric relationship applying for mammals. At 0 degree C oxygen consumption was 4.2 times that in the thermal neutral zone (TNZ) which is located at Ta of about 30 degrees C. The mean basal respiratory rate was 103 min-1 (Ta = 30 degrees C), fully 40% below the predicted value. The respiratory rate increased at 0 degree C to 3.8 times that in TNZ. The amount of oxygen consumed per breath was rather constant, increasing from a mean of 4.3 microliters (Ta = 30 degrees C) to 4.9 microliters (Ta = 0 degree C) which was only 15% above the basal value. Comparing the great changes of respiratory rate with the small alterations of oxygen consumed per breath, a dominant influence of respiratory rate in the regulation of respiration is shown. Basal heart rate was 444 min-1 (Ta = 30 degrees C), in agreement with the expected value. Heart rate increased only 1.75-fold at an ambient temperature of 0 degree C. Oxygen pulses depend very strongly on ambient temperature, increasing from 0.98 microliters (Ta = 30 degrees C) to 2.5 microliters at 0 degree C. Beat frequency and stroke volume regulation are salient features of heart function.

Animals↗
PubMed1991

Congenital bowing of the ulna and aggressive fibromatosis.

The association of skeletal anomalies and aggressive fibromatosis has been documented. Isolated bowing of the ulna is rare, yet its occurrence, particularly in conjunction with congenital dislocation of the radial head, has been documented. This article presents two cases of ulnar bowing in which the patients subsequently developed aggressive fibromatosis. We feel that aggressive fibromatosis may be a latent manifestation of congenital bowing of the ulna. The course of the disease appears to be of an aggressive nature, and patients who present with bowing of the ulna should be followed for the potential development of this disease.

Adolescent↗
PubMed1990

Neuromuscular transmission in the mdx mouse.

In both disorders, the muscle fiber plasma membrane is rendered selectively vulnerable by dystrophin deficiency. In both disorders there are also ultrastructural abnormalities involving the postsynaptic membrane of the neuromuscular junction. The object of this electrophysiologic study was to determine whether the observed ultrastructural abnormalities at the mdx neuromuscular junction are associated with an abnormality of neuromuscular transmission. In comparison with age-matched control mice, the mdx mice show an abnormal, age-dependent decrease of the amplitude of the miniature end-plate potential and a concomitant increase in the quantal content of the end-plate potential. Consequently, the safety margin of neuromuscular transmission is not impaired.

Animals↗
PubMed1989

Paradoxical social effects on response to cold during ontogeny of the common white-toothed shrew, Crocidura russula.

Postnatal development of thermoregulatory responses to cold differs between shrews measured singly or in groups as a litter. Single shrews increase their metabolic response to cold within 14 days to maintain normothermia. Shrews measured in groups show little or no metabolic response to cold and do not reach normothermia before the 19th day. Lower body temperatures in groups are explained by torpor, which obviously needs the prerequisite of forming a group. Oxygen consumption of the singly measured shrews depends upon body mass.

Animals↗
PubMed1989

Development of temperature regulation in the common white-toothed shrew, Crocidura russula.

1. Body temperature and oxygen consumption were measured during the first month of postnatal life in two litters of Crocidura russula at four different ambient temperatures. 2. Body temperature in the nest varies from 30.5-35.0 degrees C during the first 10 days; afterwards it becomes more constant (35.5-37.0 degrees C). 3. First homoiothermic reactions occur on the 2nd day of life and become effective on the 4th day. 4. In the case of undernourished shrews, torpor is already developed on the 2nd day. 5. After the 7th day torpor is the obligatory reaction in cooling experiments. 6. This discontinuous development of temperature regulation is interpreted as typical for shrews capable of torpor.

Animals↗
PubMed1989

[Gambee single modified all-layer suture].

Our modified all-layer suture technique allows surgery of colon and rectum with a low rate of anastomotic leaks (2%). In experimental animal research on pigs we compared the modified all-layer suture with the Gambee and the stapling technique. The circulation was examined by radioactive marked microspheres, by microangiograms and by special injection preparations.

Anastomosis, Surgical↗
PubMed1988

Lambert-Eaton myasthenic syndrome IgG depletes presynaptic membrane active zone particles by antigenic modulation.

The Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease that can be transmitted from human to mouse with immunoglobulin G (IgG). Electrophysiological studies indicate that LEMS IgG acts on presynaptic voltage-sensitive calcium channels, probably reducing their number, and freeze-fracture electron microscopy demonstrates that LEMS IgG has an effect on the presynaptic active zone particles, which represent putative voltage-sensitive calcium channels. The active zone particles, normally arranged in double parallel rows, move closer together, form clusters, and are reduced in number. The morphological data suggest modulation of the active zone particles crosslinked by LEMS IgG. If this were the case, then only divalent LEMS IgG and F(ab')2 should alter the deployment of active zone particles and monovalent Fab should be without effect. To test this hypothesis, mouse diaphragms were exposed to control and LEMS IgG and IgG fragments in organ culture for 24 hours and then studied by quantitative freeze-fracture electron microscopy. Divalent LEMS IgG and F(ab')2 aggregated and depleted the active zone particles, whereas monovalent Fab had no effect. The findings reconfirm that the active zone particles are targets of LEMS IgG and are direct evidence for modulation of the particles by LEMS IgG. The findings are in harmony with parallel electrophysiological studies of the effects of LEMS IgG fragments on transmitter release in the same diaphragm muscles (Lang et al, J Physiol 1987;390:173P).

Animals↗
PubMed1988

Estimates for the partial differential-Neumann problem for pseudoconvex domains in C of finite type.

We outline results obtained for the partial differential-Neumann problem for an arbitrary pseudoconvex domain in C(2) of finite type. We obtain an approximation to the Neumann operator. A number of sharp estimates for the solution of partial differentialu = f are a consequence; one of these is an extension of the L(1) estimate of Henkin and Skoda used to characterize the zero sets of functions of the Nevanlinna class.

Journal Article↗
PubMed1986

Skin and core temperatures as determinants of heat production and heat loss in the goat.

In 82 experiments on 10 goats body core temperature (Tcore) was altered between 35 degrees and 42 degrees C by external heat exchangers acting on blood temperature while skin temperature (Tskin) was maintained constant, by a circulating shower bath, at different levels between 32 degrees and 44 degrees C. At all skin temperatures at least fourfold increases of heat production (M) and respiratory evaporative heat loss (REHL) occurred when Tcore was lowered or raised, respectively. The lower Tskin was, the higher were the thresholds of Tcore, at which M or REHL exceeded resting levels. The lower Tskin was, the higher were the slopes, at which M or REHL changed per unit of Tcore. At a given Tskin, the slopes decreased with increasing M or REHL, and were dependent on the range of Tcore. The higher the range of Tcore, the steeper changed M and REHL with changing Tcore, if all other variables were held constant. The results support the concept that an exponential relationship between Tcore and the rate of core temperature signals is the primary cause of the effects exerted by Tskin on the slopes, at which M or REHL change per unit of Tcore.

Animals↗
PubMed1986

The electrocardiogram of European shrews.

A recording method of electrocardiograms in resting animals is described. The electrocardiograms of Crocidura russula, Crocidura leucodon, Crocidura suaveolens, Neomys fodiens and Sorex araneus are similar to those of other small mammals. T-wave directly follows the QRS-complex. The duration of electrocardiograms depends on heart mass and body temperature. Heart rate shows no influence on the duration of electrocardiograms.

Animals↗
PubMed1984

Circulation and acid-base balance in exercising goats at different body temperatures.

Thirty experiments were performed in two goats at an air temperature of +35 degrees C and a relative humidity of 33%. By means of heat exchangers, body core temperature (Tpaor) was adjusted to 39, 40.5, or 42 degrees C and maintained at these levels for 120 min. During the last 60 min the animals worked at a rate of 1.2 W/kg (treadmill, 3 km/h, 15%). Blood gases (arteriovenous O2 difference, Po2, Pco2), hemoglobin (Hb), blood lactate (LA), cardiac output (CO), blood pressure (MAP), heart rate (HR), metabolic rate (M), and respiratory evaporative heat loss (REHL) were determined. M, CO, HR, and Hb increased with exercise and were independent of Tpaor. At rest and exercise, REHL increased and Pco2 decreased at higher levels of Tpaor resulting in a respiratory alkalosis. During exercise this was accompanied by an increase in LA. At all instants, the concentrations of LA were higher at higher Tpaor. It is concluded that in a virtually nonsweating species like the goat the overall stress on the circulatory system caused by hyperthermia during exercise is relatively small while the behavior of blood LA is indicative of a temperature-dependent accumulation of LA also in the exercising muscle.

Acid-Base Equilibrium↗