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Biomedical subjects

B Larsen

Publications and source records attributed to B Larsen.

At least 271 records · Page 15Linked to original sources
PubMed1977

A multidetector scintillation camera with 254 channels.

A computer-based scintillation camera has been designed for both dynamic and static radionuclide studies. The detecting head has 254 independent sodium iodide crystals, each with a photomultiplier and amplifier. In dynamic measurements simultaneous events can be recorded, and 1 million total counts per second can be accommodated with less than 0.5% loss in any one channel. This corresponds to a calculated deadtime of 5 nsec. The multidetector camera is being used for 133Xe dynamic studies of regional cerebral blood flow in man and for 99mTc and 197 Hg static imaging of the brain.

Brain Neoplasms↗
PubMed1976

Polymerization of protamine sulphate by carbodiimide and interaction of isolated protamine polymers with human red blood cells.

A method using a water-soluble carbodiimide to polymerize protamine sulphate is described. The behaviour of polymerized protamine in Sephadex chromatography and in polyacrylamide gel electrophoresis indicates that protamine has been polymerized into aggregates with defined molecular weights. Turbidimetrical titrations of the isolated protamine polymers with dextran sulphate show that the cationic charge density has been conserved after polymerization. The binding characteristics of the protamine polymers to human red blood cells as measured by cell electrophoresis indicate increased affinity with increased molecular weight of the polymer.

Binding Sites↗
PubMed1976

Focal increase of cerebral blood flow during stereognostic testing in man.

An attempt was made to study the regional cerebral blood flow (rCBF) pattern during stereognostic discrimination in man. The rCBF was measured in 18 subjects who had no major neurological defects. The clearance from the hemisphere of xenon 133 injected (133Xe) into the carotid artery was measured with a 254-channel dynamic gamma camera. During stereognostic discrimination with hand, mouth, or foot, the rCBF increased focally in the corresponding contralateral sensory-motor region and increased focally in the premotor part of the frontal lobe. The increase in the sensory region was attributed to the work of neurons extracting spatial features from the received input, while the increase in the motor region was ascribed to the formulation of motor strategies and motor commands. The physiological significance of the increase in the frontal region was unclear, tentatively, it was suggested to reflect the intention, selective attention, and decision of the subject.

Adult↗
PubMed1976

Quantitative alterations in the genital microflora of female rats in relation to the estrous cycle.

The virgin female laboratory rat has been studied as a model of the ecosystem represented by the vaginal mucosa and its bacterial flora. Gram-stained vaginal smears abtained from rats having normal estrous cycles showed cyclic variation in the number of bacteria present. Viable plate counts of material obtained by vaginal lavage demonstrated daily changes in the density of the bacterial population of the vagina in relation to the estrous cycle. Bacterial counts observed during the estrus phase of the cycle in individual rats were 10,000 to 100,000 times greater than viable counts observed during the metestrus or diestrus phases of the cycle. These studies represent the first reported demonstration that physiologic changes occurring during the estrous cycle control the size of the bacterial population of the vagina.

Animals↗
PubMed1976

Human agglutinins to rabbit erythrocytes. Characterization of an antigen.

Crude preparations inhibiting the agglutination of rabbit erythrocytes by pooled human serum were obtained by extraction of erythrocyte stromata with various solvents (chloroform/methanol, trichloroacetic acid, and so forth). Highest inhibiting activity was found in a preparation containing sphingoglycolipid; 0.8 mug inhibited 2 agglutinating units of serum. The active preparations retained their activity after 5 min of incubation in a boiling water bath and after treatment with proteolytic enzymes or neuraminidase. Treatment with periodate abolished the activity. The antigenic site is therefore probably determined by the sugars of the sphingoglycolipid.

Agglutination Tests↗
PubMed1976

HLA haplotypes in a genetic isolate in Newfoundland. A population showing 8% homozygosity and a familial aggregate of lymphoma and immunodeficiency cases.

HLA typing was performed on 384 individuals of an isolated population of 1,500 people with a familial aggregate of lymphoma and immunodeficiency cases. Eighty-five % of the total population were descendants of the founding couple. First cousin marriages were common. There was a three-fold or higher increase of the following haplotypes as compared to the frequencies in Sheffield: HLA-A28,Bw35, HLA-A28, B18, HLA-A10, B18, HLA-A2, B18,HLA-A11, Bw40 and HLA-A11, B7. The frequency of HLA-A1, B8 was low (5.4%). The most common genotype was HLA-A2, B12/A2, B12 followed by HLA-A2, B12/A28, Bw35. We found 20 HLA homozygous individuals, of these 15 were HLA-A2, b12/a2, b12. There were two possible HLA cross-overs which may be confirmed and three postulated cross-overs which can never be confirmed as one or both parents of the individuals in question are deceased. Some of the haplotypes could be traced back to the first, second and third generations, i.e. to the first half of the nineteenth century. No single haplotype or antigen was shared by the patients.

Consanguinity↗
PubMed1976

Influence of antibodies and thermolabile serum factors on the bactericidal activity of human neutrophil granulocytes.

The influence of serum natibodies and thermolabile serum factors on the intracellular killing of Staphylococcus aureus by neutrophil granulocytes has been examined using a method which facilitates a precise in vitro evaluation of the phagocytic and bactericidal activities of human polymorphonuclear leucocytes. The bactericidal activity of the granulocytes was significantly less pronounced in the presence of serum absorbed with Staph. aureus or inactivated at 56 degrees C for 30 minutes than in the presence of untreated serum. Specific antibodies seemed to stimulate the intracellular killing of bacteria more than thermolabile serum factors.

Antibodies↗
PubMed1976

Influence of IgG, F(ab')2 and IgM on the phagocytic and bactericidal activities of human neutrophil granulocytes.

The phagocytosis and intracellular killing of Staphylococcus aureus by humans granulocytes in the presence of immunoglobulin preparations have been examined. Isolated IgG from pooled human serum induced phagocytosis and intracellular killing of bacteria. F(ab')2 fragments had no significant effect, indicating that the Fc piece of the IgG molecule is of importance not only for the phagocytosis but also for the intracellular killing of bacteria. Isolated IgM stimulated the phagocytosis to a minor extent, with no enhancement of the bactericidal activity.

Blood Bactericidal Activity↗
PubMed1976

The bacterial flora of the female rat genital tract.

A study of the genital microflora in virgin female rats of reproductive age has demonstrated that alpha and nonhemolytic streptococci, Pasteurella pneumotropica, diphtheroid bacilli, Staphylococcus epidermidis, and Proteus mirabilis are the predominant genital organisms. The pH of the rat vagina was demonstrated to be near neutrality. It is suggested that the higher pH in the rat vagina as compared to the human vagina may account for some of the differences between human and rat genital microflora.

Animals↗
PubMed1976

Permanent pacemaker treatment at Gentofte hospital. A follow-up study with special reference to transvenous electrode complications, generator longevity and control procedures.

Results of a follow-up study of 125 patients treated with permanent pacemakers at Gentofte Hospital during the years 1962--1973 are presented. Complications with endocardial electrodes are reported and longevity curves of pacemaker units are given. The series shows a high frequency of electrode displacement in the first three months and battery exhaustion from the 18th to the 42nd month. The appearance of complications correlates with the frequences of check-up intervals. In order to predict pacing failure due to battery exhaustion, there would seem to be some merit in carrying out an oscilloscopic display of the pulse artifact in addition to the usual measurement of pulse frequency. The aim of this retrospective report is, by analysing a pacemaker series for sudden eletrode failures and battery longevity, to comment on the value of check-up procedures in an outpatient pacemaker clinic.

Adult↗