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Biomedical subjects

A Keller

Publications and source records attributed to A Keller.

At least 235 records · Page 13Linked to original sources
PubMed1982

Alterations in tyrosine hydroxylase activity elicited by raphe nuclei lesions in the rat locus coeruleus: evidence for the involvement of serotonin afferents.

The time course of the variations in tyrosine hydroxylase (TH) activity was measured in the rat locus coeruleus (LC) after lesions of the nucleus raphe dorsalis (NRD), nucleus raphe centralis superior (NRCS) and nucleus raphe pontis (NRP). A certain number of lesions were performed in the raphe magnus (RM), the caudal and rostral NRP and the caudal and rostral NRCS, lateral to raphe nuclei and in adrenalectomized animals. The serotonin (5-HT) content in the LC was also determined after these lesions. Only raphe nuclei producing significant decreases in the 5-HT content in the LC are successful in provoking increases in the TH activity in the LC, thus these results suggest that the noradrenaline (NA) synthesis in the LC may be regulated by 5-HT afferents. Moreover, intraventricular injections of 5,6-dihydroxytryptamine (5,6-DHT) and administration of parachlorophenylalanine (PCPA) also produce significant increases in TH in the LC. After immunotitrations of TH in the LC it was shown that, with exception of a high dose of 5,6-DHT (75 micrograms), all these treatments provoke an increase in the concentration of the enzyme. It therefore seems that one of the functional roles of 5-HT in the LC could be the regulation of the concentration of TH.

5,6-Dihydroxytryptamine↗
PubMed1981

[In vitro synthesis of tyrosine hydroxylase].

RNA from PC 12 cells was translated in a cell-free system and the peptides synthesized in vitro were analyzed by immunoprecipitation with an anti-T.H. serum raised in Rabbit. Analysis of the immunoprecipitate on a SDS-polyacrylamide gel reveals a major band with a molecular weight of 62000 dalton. A protein of the same molecular weight was also precipitated from a PC12 cell lysate. This molecular weight of 62000 dalton corresponds to the reported for tyrosine hydroxylase purified from PC12 cells.

Animals↗
PubMed1981

A comparative immunohistological study of cerebellar enolases. Double labelling technique and immunoelectronmicroscopy.

A comparative immunohistological study of the neurone-specific gamma gamma enolase and alpha alpha enolase, demonstrates the exclusive neuronal localization of gamma gamma enolase and its absence from glial cells. In contrast, alpha alpha enolase is located in astroglial cells. The validity of gamma gamma enolase as a neuronal marker and alpha alpha enolase as an astrocytic marker, is confirmed both by a double labelling technique, using antibodies to alpha alpha and to gamma gamma revealed with fluorescence or peroxidase in the same tissue sections, and by immunoelectronmicroscopy.

Animals↗
PubMed1981

[Intracondylar knee joint prosthesis with rotation capacity- Endo model].

The St. Georg total knee prosthesis has been modified to incorporate axial rotation of the tibial component. The kinematics approximate more those of the normal knee and the stress imposed at the bone-cement interface are attenuated, thus reducing the risk of mechanical failure. The construction and laboratory testing are described.

Biomechanical Phenomena↗
PubMed1980

[Micromethod of measuring the 3 brain isoenzymes of enolase].

The brain of the vertebrates contains three isozymic forms of the glycolytic enzyme enolase, two of which are neuron specific. These proteins could therefore be utilized as biochemical markers for various studies of neurons. We have devised a separation procedure which allows the measurement of the three enolase forms from minute amounts of tissue (50 to 100 microgram total protein). We show that this method can be applied to studies of brain microstructures, in vivo and in vitro (clonal cell lines) neural differentiation, and in measurements in biological fluids.

Animals↗
PubMed1980

The Pennsylvania hemophilia program 1973-1978.

In Pennsylvania, the prevalence of hemophilia is one per 10,000 males. Factor VIII deficiency is five times more frequent than Factor IX deficiency, and 34% of the patients have no relatives affected with the disease. The mean age is 23 years old, and 50% of the patients are less than 20 years old. Approximately one-third of the patients with Factor VIII deficiency and one fourth of the patients with Factor IX deficiency have levels of less than 0.01 mu/ml. By clinical criteria, 55% of those with Factor VIII deficiency are severe compared to 45% of those with Factor IX deficiency. Factor VIII-deficient patients are treated an average of 18 times per year compared to ten times per year for patients with Factor IX deficiency. Hemarthroses account for 70% of the hemorrhages treated and for 40% of the concentrate usage. Home therapy patients use an average of 45,950 Factor VIII units per year at a cost of ø170 per patient and their use accounts for 60% of the total Factor VIII usage of 1.7 million units. Less than five days per patient per year are lost from school or work because of bleeding, and patients are hospitalized for bleeding an average of only two to three days per patient year. Adverse immediate reactions to therapy are infrequent. Five percent of patients have persistence of the hepatitis B virus, and 7.5% have inhibitors. The mortality rate is 0.04% per year, with half of the deaths being hemophilia-related.

Adult↗
PubMed1980

[Experimental study of the optimization of the hip endoprosthesis].

Clinical and laboratory investigations have resulted in a new design for the shaft prosthesis of the "St. Georg" model total hip prosthesis, the purpose of which was to minmize the risk of biomechanical complications. The original method of attachment and the same material for the limb were retained for our investigations. It was possible to test the bending strength, the length, and the geometry of the shaft as well as how structure of the bearing surface of the collar influences the force flow within the compound system. The distrubances produced in physiological force flow produced on insertion were also investigated. The results obtained enabled us to design a new shaft prosthesis.

Biomechanical Phenomena↗
PubMed1978

X-ray diffraction effects related to superstructure in rat tail tendon collagen.

A number of unusual X-ray diffraction effects concerning the meridional low angle reflections of collagen are presented which are due to structural inhomogeneities in the 100 micron range within the tendon such as are expected to be associated with the planar crimp structure of tendon units. These newly observed effects provide diffraction confirmation for such a crimped morphology. The effects consist of splitting of the reflections both azimuthally and radially. Azimuthal split varied with rotation of the tendon unit around its own axis and is directly related to the existence of the crimp, its angle and planarity. Radial splitting is a consequence of the limited sampling of the micro-structure by the collimator, which provides further support for the crimp morphology and conveys added information about the crimp form. It is shown that this limited sampling can provide a kind of "micro-X-ray topography" technique for the study of micro-textures on the appropriate dimensional level, while ti could be the source of misrepresentation if its origin remains unrecognized. The effect of stretching is examined and interpreted in terms of crimp straightening. Simultaneous examination of medium angle equatorial reflections, when combined with some electron micrographs point to further issues concerning the relation between the large scale and fibril substructure. It is believed that the present findings have general implications for structure research on collagen.

Animals↗
PubMed1978

Low temperature electron diffraction and beam effects in tendon collagen.

In the course of experiments to obtain electron diffraction from forzen rat tail tendon (RTT) collagen, a characteristic development of perforations relating to the banding pattern was observed under conditions of moderate beam intensity. This is most likely to be due to an etching process resulting from ionization or sublimation of bound or preferentially retained water molecules in the band-interband region and could provide a means of visualization of the location of such water.

Animals↗
PubMed1977

Recent trends in contraceptive use in Mexico.

In 1973 the Mexican government changed its official position on family planning from one of neurtality to one of support. Prior to that time, family planning activities had been limited to the commercial sector and two private programs. As a result of the new policy, all major official health programs began organizing family planning activities. While about the same number of couples were served by the private programs in 1976 as in 1973, the commercial sector grew at over 10 percent per year and official coverage expanded around fivefold. It is estimated that the proportion of eligible women protected by contraception doubled and that the birth rate fell from 43-44 in 1973 to 37-40 by the end of 1976.

Adolescent↗
PubMed1976

Isolation and characterization of rat olfactory marker protein.

The olfactory marker protein was isolated and characterized from rat olfactory bulbs. Its properties and those of the olfactory marker protein isolated from the mouse are described. The rat protein was less acidic (pI = 5.0) than the mouse protein (pI = 4.7). However, the amino acid compositions were very similar: in both proteins arginine plus lysine accounted for 13 mol% and glutamate plus aspartate for 30 mol% of the total residues. Molecular weights of both proteins estimated by sodium dodecyl sulfate gel electrophoresis were indistinguishable and estimated to be 16,500. The molecular weight of the native rat olfactory marker protein estimated by gel filtration techniques was 30,000, which is identical to the molecular weight of the native mouse and garfish olfactory marker proteins. This suggested a dimeric structure. The purified rat and mouse proteins behaved like species of 35,000 molecular weight on gel filtration.

Amino Acids↗