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Biomedical subjects

E Meyer

Publications and source records attributed to E Meyer.

At least 253 records · Page 14Linked to original sources
PubMed1986

Organization and evolution of D region class I genes in the mouse major histocompatibility complex.

Chromosome walking has been used to study the organization of the class I genes in the D and Qa regions of the MHC of the BALB/c mouse and in the D region of the AKR mouse. Five and eight class I genes are found in the D and Qa regions of the BALB/c mouse, respectively, while the AKR mouse contains only a single class I D region gene that has been identified by transfection as the Dk gene. Restriction map homologies and crosshybridization experiments suggest that the multiple class I genes in the D region of the BALB/c mouse have been generated by unequal crossing-over involving class I genes from the Qa region. The expanded D region of BALB/c and other H-2d haplotype mouse strains appears to be metastable, since evidence for gene contraction in the Dd region has been found in two mutant strains. Thus the D region and also the Qa region class I genes are in a dynamic state, evolving by gene expansion and contraction.

Animals↗
PubMed1986

X-ray crystal structure of the complex of human leukocyte elastase (PMN elastase) and the third domain of the turkey ovomucoid inhibitor.

Orthorhombic crystals diffracting beyond 1.7 A resolution, have been grown from the stoichiometric complex formed between human leukocyte elastase (HLE) and the third domain of turkey ovomucoid inhibitor (OMTKY3). The crystal and molecular structure has been determined with the multiple isomorphous replacement technique. The complex has been modeled using the known structure of OMTKY3 and partial sequence information for HLE, and has been refined. The current crystallographic R-value is 0.21 for reflections from 25 to 1.8 A resolution. HLE shows the characteristic polypeptide fold of trypsin-like serine proteinases and consists of 218 amino acid residues. However, several loop segments, mainly arranged around the substrate binding site, have unique conformations. The largest deviations from the other vertebrate proteinases of known spatial structure are around Cys168. The specificity pocket is constricted by Val190, Val216 and Asp226 to preferentially accommodate medium sized hydrophobic amino acids at P1. Seven residues of the OMTKY3-binding segment are in specific contact with HLE. This interaction and geometry around the reactive site are similar as observed in other complexes. It is the first serine proteinase glycoprotein analysed, having two sugar chains attached to Asn159 and to residue 109.

Animals↗
PubMed1986

Effects of rapid mannitol infusion on cerebral blood volume. A positron emission tomographic study in dogs and man.

Positron emission tomography was used to study the effect of a rapid infusion of mannitol on cerebral blood volume (CBV) in five dogs and in three human subjects. The ability of mannitol to reduce intracranial pressure (ICP) has always been attributed to its osmotic dehydrating effect. The effects of mannitol infusion include increased osmolality, total blood volume, central venous pressure (CVP), and cerebral blood flow, and decreased hematocrit, hemoglobin concentration, serum sodium level, and viscosity. Mannitol's ability to dilate the cerebral vasculature, either directly or indirectly, and thus to transiently increase ICP, is a subject of controversy. By in vivo labeling of red cells with carbon-11, the authors were able to demonstrate an early increase in CBV in dogs of 20%, 27%, and 23% (mean increase, p less than 0.05) at 1, 2, and 3 minutes, respectively, after an infusion of 20% mannitol (2 gm/kg over a 3-minute period). The animals' muscle blood volume increased by 27% (mean increase, p less than 0.05) 2 minutes after infusion. In the human subjects, lower doses and a longer duration of infusion (1 gm/kg over 4 minutes) resulted in an increase in CBV of 8%, 14% (p less than 0.05), and 10% at 1, 2, and 3 minutes, respectively, after infusion. In dogs, ICP increased by 4 mm Hg (mean increase, p less than 0.05) 1 minute after the infusion, before decreasing sharply. The ICP was not measured in the human subjects. Hematocrit, hemoglobin, sodium, potassium, osmolality, heart rate, mean arterial pressure (MAP), and CVP were measured serially. Results of these measurements, as well as the significant decrease in MAP that occurred after mannitol infusion, are discussed. This study demonstrated that rapid mannitol infusion increases CBV and ICP. The increase in muscle blood volume, in the presence of a decreased MAP and an adequate CVP, suggests that mannitol may have caused vasodilation in these experiments.

Adult↗
PubMed1986

[X-ray examination of foot injuries].

Fractures and luxations of the phalanges, metatarsus, tarsus and their joints are discussed. Correct radiological projections, knowledge of their pitfalls and a systematical interpretation are necessary for correct diagnosis.

Calcaneus↗
PubMed1986

Effects of immunosuppressive drugs on the morphology of the microvilli in Sjögren's syndrome.

Electron microscopic study of conjunctiva in two cases of Sjögren's syndrome showed decrease in height and number of microvilli and lack of branching. Following immunosuppressive treatment, an increase in height, number and branching of conjunctival microvilli was observed. Notwithstanding the lack of influence on tear secretion, immunosuppressive drugs are of benefit in the treatment of ocular manifestations of Sjögren's syndrome. The increase in number, height and branching of microvilli enlarge the surface of the conjunctiva and thus improve the efficacy of artificial tears.

Azathioprine↗
PubMed1986

Light damage in the developing retina of the albino rat: an electroretinographic study.

The albino rat retina is severely damaged by exposure to bright light. The degree of damage depends upon the intensity of the exposure and its duration. In the present study, electroretinographic (ERG) responses were measured in rats exposed at different ages during the period of retinal development to 24 hr of bright light and then transferred to darkness for about 2 months. The ERG data indicated that if the bright-light exposure was done prior to 20 days of age, the retina was resistant to the light damage, and the dark-adapted ERG responses measured later were normal. In rats older than 20 days, light damage increased with age until, in rats exposed to light at age 30 days, the ERG was unrecordable. Further experiments showed that light exposure did damage the 15-day-old rat retina; however, complete recovery was attained within 15 days postexposure.

Aging↗
PubMed1986

Sudden loss of vision in a monocular patient, caused by visual cortex infarction.

Infarction of the occipital cortex usually causes loss of the contralateral half of the visual field in both eyes. Although cases with complete transient loss of vision have been described, this is due to involvement of the second half of the cortex in the pathologic process. We report a case of a one-eyed patient with almost complete loss of vision in her only eye because of an infarction of the ipsilateral occipital cortex. During the patient's hospitalization, the temporal half of the visual field recovered. The case is of interest because of the difficulties in diagnosing cortical blindness in a one-eyed patient.

Aged↗
PubMed1985

[Behavior of HDL cholesterol and the apoproteins A1 A2 and B in the central circulation in patients with coronary disease and genetically determined hyperlipoproteinemias].

Seven lipid parameters, including apoproteins A1, A2 and B were determined in blood from different parts of the cardiovascular system in two groups of patients one with and the other without coronary heart disease. In addition, HDL cholesterol levels were compared in patients with coronary heart disease and primary monogenic combined hyperlipoproteinaemia. None of the seven parameters showed significant differences in samples from the pulmonary artery (mixed venous blood) and the hepatic vein of the control and patient groups. The expected significant concentration gradient between the two vascular regions was confirmed in the groups with and without coronary heart disease. HDL components showed a contrary behaviour: the hepatic vein and pulmonary artery exhibited significantly lower values of HDL cholesterol in patients with coronary heart disease than in the controls, but this was not true for HDL apoproteins A1 and A2. Patients with coronary heart disease and primary hyperlipoproteinaemia showed a significant concentration gradient between the two vascular regions for total and HDL cholesterol. These observations reveal the importance of genetic disturbances of lipid metabolism, particularly the implication of various lipid fractions in the pathogenesis of atherosclerosis.

Apoproteins↗
PubMed1985

The effects of rapid infusions of saline and mannitol on cerebral blood volume and intracranial pressure in dogs.

The role of osmotic brain dehydration in the early reduction of intracranial pressure (ICP) following mannitol administration has recently been questioned and a decrease in cerebral blood volume (CBV) proposed as the mechanism of action. To evaluate this hypothesis, relative CBV changes before and after mannitol infusion were determined by collimated gamma counting across the biparietal diameter of the exposed skull in six dogs. Red blood cells were labelled with chromium-51. Cerebral blood volume (CBV), total blood volume (TBV), ICP, mean arterial pressure (MAP), central venous pressure (CVP), haematocrit and osmolality were serially measured after infusions of 10 ml X kg-1 of normal saline (control study) and of 20 per cent mannitol (mannitol study). The solutions were administered over a two-minute period; a 30-minute equilibration period intervened between the saline and mannitol infusions. We demonstrated that the mannitol infusion was associated with significant increases in relative CBV (25 per cent), ICP (7 mmHg), CVP (11 cm H2O), and TBV (50 per cent). MAP declined significantly (14 per cent) after mannitol infusion. The administration of saline, although associated with an increase in TBV (18 per cent), was not associated with any significant change in CBV, ICP, MAP or CVP. The increase in relative CBV persisted for 15 minutes after mannitol infusion, while the ICP returned to control within five minutes and continued to decrease. This study supports the fact that after rapid mannitol infusion, ICP begins to decrease only once the dehydrating effect has counteracted the increase in brain bulk caused by the increase in cerebral blood volume.

Animals↗
PubMed1985

Brainstem auditory evoked potentials in meningomyelocele.

The brainstem auditory evoked potentials (BAEP) of twenty-seven Myelomeningocele (MMC) patients were analyzed and compared with the results of a normal population. The longest wave V or V-I interpeak latencies were seen in patients with shunted hydrocephalus and cranial nerve defects. The shortest wave V and V-I interpeak latencies were found in patients without hydrocephalus. However, these latencies of MMC patients were significantly longer than the latencies of a normal population. Wave I latencies of all MMC subgroups were not significantly different from the results of the normal probands. It is assumed that V-I interpeak latency prolongation in MMC patients, which is related to the severity of the clinical signs of the Arnold Chiari malformation, is mostly due to an elongation of the brainstem.

Adolescent↗