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Biomedical subjects

B Larsen

Publications and source records attributed to B Larsen.

At least 37 records · Page 2Linked to original sources
PubMed1979

On the pathogenesis of bedsores. Skin blood flow cessation by external pressure on the back.

This paper is devoted to elucidation of the question: Which external pressure is required to stop skin blood flow at the skin - support interface in humans lying on the back in the supine position? Cessation of blood flow was recorded as cessation of washout of an intracutaneous depot of 131I-antipyrine mixed with histamine. The external pressure was measured by a small airfilled plastic cushion connected to a mercury manometer. In 11 normal subjects, eight patients with hypertension and seven patients with tetra- or paraplegia the "flow cessation external pressure" (FCEP) was strongly correlated to the auscultatory brachial mean blood pressure (p less than or equal to 0.001). The difference mean blood pressure - FCEP was on average 4 mmHg (range (-11) - (+20) mmHg) and there was no significant difference between the three groups studied. Thus external pressure exceeding the actual mean blood pressure will stop skin circulation.

Adult↗
PubMed1979

[Activation of supplementary motor areas during voluntary movements in man studied by measurement of focal cerebral blood flow (author's transl)].

Focal activation in the cerebral cortex during different motility and language tests in 52 patients examined by arteriography was studied by measuring focal cerebral blood flow (fCBF) by means of an apparatus of high resolution. A sterotactic or functional approach demonstrated that the upper premotor activation previously noted in certain types of movement, corresponds to supplementary motor area (SMA). A retrospective study of 157 maps of fCBF recorded during motor or verbal behaviour, compared to 90 recordings in subjects at rest, showed that SMA is involved in most voluntary movements, either verbal or non-verbal. An analysis of the results suggests that SMA acts during the establishment of new motor programs, and in the control of pre-established automatic activities, in response to internal and external stimuli.

Brain Mapping↗
PubMed1978

Modification of lymphocyte response to phytomitogens by polycations and polyanions.

The stimulating effect on mitogen-induced lymphocyte response by polycationic compounds such as polylysine, DEAE dextran protamine and methylated albumin, is studied at different serum-protein concentrations and mitogen concentrations. It is suggested that the polar interaction between polycationic compounds and glycoproteins are of major importance for reactivity of lymphocytes to mitogens.

Anions↗
PubMed1978

Regional cerebral blood flow in aphasia.

Regional cerebral blood flow (rCBF) was studied in 13 aphasic patients with left hemisphere lesions, using the intracarotid xenon 133 injection method and a 254-detector gamma camera system. The rCBF was measured during rest and during various function tests, including a simple speech test. In motor (nonfluent) aphasia, the rCBF method showed areas of cortical dysfunction that always included the lower part of the rolandic area while Broca's area was not consistently affected. In sensory (fluent) aphasia, the superior-posterior temporal cortex was involved in all cases. In global aphasia, the abnormalities included both regions consistently involved in the other types of aphasia. The 133Xe injection method for mapping abnormalities relevant for localizing the cortical speech areas was superior to the classical neuroradiological methods in that several cases failed to show any relevant lesion whatsoever. This is probably related to the functional nature of the rCBF method: subnormal flow values and lack of the normal flow increase during function tests apparently may disclose functionally inactivated but structurally intact cortex.

Aged↗
PubMed1978

Reverse phase high pressure liquid chromatography for the separation of peptide hormone diastereoisomers.

Diastereoisomers of specifically labeled oxytocin derivatives were resolved using reverse phase high pressure liquid chromatography. The peptides [1-hemi-DL-[alpha-2H]cystine]oxytocin, [6-hemi-DL-[alpha-2H]cystine]oxytocin, [2-DL-[alpha-2H]tyrosine]oxytocin and[8-DL-[2-13C]leucine]oxytocin were readily separated using the conditions described. The diastereoisomers of the oxytocin analog [3-DL-[2-13C]leucine]oxytocin also demonstrated baseline resolution under the same conditions. The procedure offers the investigator a rapid method for screening synthetic oxytocin peptides for undesirable diastereoisomeric by-products.

Chromatography, High Pressure Liquid↗
PubMed1978

Host-parasite interactions during pregnancy.

The point that host defense against infectious disease is exceedingly complex scarcely needs further emphasis. We have tried to show that pregnancy is a state which has the potential for altering any of the many facets of host defense, and in some instances presented evidence that pregnancy does alter resistance to infection. Some diseases are either more severe during pregnancy or more prevalent during pregnancy, suggesting a softening of the host defenses. However, both monocytic and polymorphonuclear leucocyte phagocytic systems seem to be more active during pregnancy. Transferrin is increased in pregnancy. The immune system in pregnancy is either normal or slightly depressed. A number of other factors have been mentioned for which no information exists as to the effect pregnancy has on them. Despite the information reviewed, it is not possible to say that pregnancy has a net positive or negative effect on host defense; the effect, if any, depends ostensibly on the disease entity. That the host defenses may be somewhat enhanced by pregnancy while susceptibility to certain diseases is increased is paradoxical and serves to underscore the fact that our understanding of host defense in pregnancy is abysmally deficient. Probably no concept is made more clear by this paper than the idea that in the area of host defense in pregnancy there is as much space as any researcher may choose to fill.

Female↗
PubMed1978

Natural and immune antibodies to rabbit erythrocyte antigens.

Natural agglutinins to rabbit erythrocytes were found in all human sera studied. In the newborn, the antibodies were of IgG class; in the 6-month-old infants they were mainly of IgM class. Older children and adults had both IgG and IgM antibodies. Agglutinins to rabbit erythrocytes were also found in serum from fourteen of fifteen other species studied. The trichloroacetic acid extract from rabbit erythrocyte stromata (TCA-preparation) contains at least three different antigenic determinants: one which we hitherto to have found only on rabbit erythrocytes, one which is closely related to human blood group B antigen, and one which is closely related to the I antigen. The TCA-preparation did not elicit delayed hypersensitivity skin reactions in humans in spite of high titred agglutinins in serum, but did so in immunized guinea-pigs.

Adolescent↗
PubMed1978

Tuberculosis associated with HLA--B8, BfS in a Newfoundland community study.

In three adjacent Newfoundland communities comprising some 1500 people, 589 people have been HLA typed. Forty-six of the typed people gave a history of previous clinical tuberculosis which required treatment. Fifty-six percent of the TB patients carried HLA B8 compared with 20% of the remainder of the population. This is a highly significant difference (P less than 0.01). In each community the frequency of B8 as an epidemiological marker correlated with the incidence of tuberculosis. B8 is associated with TB in ths study with a relative risk of 5.2 which compares with combined relative risks in the literature for coeliac disease and Addison's disease of 9.5 and 6.4, respectively, and which is greater than the risks for all the other B8-related diseases. The factor B allele, Bf S, was found on all the B8 haplotypes, but the overall Bf gene frequencies in tuberculosis patients did not deviate from expected values.

Cytotoxicity Tests, Immunologic↗
PubMed1978

HLA/Bf haplotypes in a Newfoundland family.

HLA/Bf haplotypes were examined in a large three-generation Newfoundland family with a high incidence of Graves' disease. In that family Graves' disease was inherited in association with the haplotype HLA Aw24, Bw39 in some instances and with HLA B8-containing haplotypes in other instances. As all seven members of the family who suffered from Graves' disease were homozygous for the Bf S allele, the study for Bf was uninformative. However, the examination of other HLA/Bf haplotypes disclosed some interesting associations. One-hundred-and-five out of 168 HLA-A, -B, -Bf haplotypes were Bf S. Although numerically deviant, no unusual HLA B/Bf associations were observed. Bf F entered the family only once. A new finding is the association between HLA B27 and Bf S1; the haplotype entered the family once and was passed on to eight family members over three generations. Bf S1 was previously reported in association with HLA B12 or W21. None of these family members had ankylosing spondylitis. The Bf allele F1 entered the family three times, always in association with HLA B18.

Alleles↗
PubMed1978

[Cortical localizations seen by the dynamic gamma-camera : a new approach in neuropsychology].

We present here the results obtained in the study of normal brain functions, in normal awake man performing normal voluntary tasks, by mean of new approach developed in our laboratory. Its principle lies on the fact that focal changes in cortical blood flow during brain function are due to the coupling between local function aand metabolism, which has been demonstrated in man during hand movement by Olesen (1971) and by Raichle and associates (1976). So far as the changes are focal (uni- or multifocal) they can be assessed by external measurement of focal cerebral blood flow (rCBF) with the 133Xenon clearance technique, provided that the detection apparatus used yields a proper spatial and temporal resolution. A temporal resolution of 45 sec. is made possible by the initial slope calculation of Olesen and coll. (1971), using intracarotid injection of isotope. The spatial resolution has been improved by the design of a special system using 254 scintillation detectors with individual collimation, each 8 mm ø, connected to individual ratemeters (Sveinsdottir et al., 1975). This allows the simultaneous processing of the 254 clearance curves by a small on-line Varian computer. The results are displayed as functional colour pictures of the brain on a T.B. screen, less than 3 min. after isotope injection. The studies have been performed to date in more than 200 patients, usually in connection with carotid angiography. 84 subjects could be classified as "normals+ because of lack of detectable brain lesion and of permanent symptoms, and they constitute the reference material for exploring normal brain functions. In each case one or two "rest" studies have been made for comparison with the test situations. The following observations were made: Resting pattern: with the patients lying in a quiet dark room with minimal sensory input the normal pattern is much the same in both hemispheres and it is characterized by higher flows in the anterior upper parts of the frontal lobes (fig. 1 a). The percent variation in a given area during two different rest studies is about 5 percent (fig. 1 b). Primary sensory inputs. Auditory and visual inputs activate the corresponding parts of temporal and occipital regions (fig. 2 and 3). Simple cutaneous stimulation such as touch or vibrations do not change the rest pattern. Moderate pain gives a global increase of CBF, pre-dominantly in the frontal regions (Ingvar, 1976). Vestibular stimulation with cold or warm water in the ear gives an increase of rCBF in the parietal regions. Simple movements. Movements of mouth, eyes, hand or foot clearly activate the corresponding parts of the central region, with an increase of rCBF up to 50--100% (Sveinsdottir et al., 1975). When the movement is repetitive there is in all cases an additional clearcut increase in the upper premotor region, probably including the supplementary motor area. This last region is activated alone when the subject tries to imagine a movement without actually moving (fig. 5 a, b, c). Sensory discrimination...

Acoustic Stimulation↗