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Biomedical subjects

B Larsen

Publications and source records attributed to B Larsen.

At least 19 recordsLinked to original sources
PubMed1979

Activation of the supplementary motor area during voluntary movement in man suggests it works as a supramotor area.

Measurements of cerebral blood flow in man revealed that complex voluntary movements are associated with a blood flow increase in the supplementary motor area of the brain. This increase is additional to and similar in magnitude to the Rolandic sensorimotor area activation that occurs during all kinds of movement. When subjects counted silently there was no activation of any focal cortical area in the brain; when they counted aloud there was a marked increase in activity in the supplementary motor area. These results are consistent with the hypothesis that the supplementary motor area plays a major role in the initiation and control of at least some kinds of voluntary movement in man and is, therefore, a motor center of a higher order than the primary Rolandic areas.

Cerebrovascular Circulation↗
PubMed1979

Bacterial growth inhibition by amniotic fluid. VIII. Evaluation of a radiometric bioassay for rapid, in vitro demonstration of phosphate-sensitive bacterial growth inhibitor in amniotic fluid.

A radiometric bioassay based on the continuous monitoring of 14CO2 released from labeled glucose in the presence of amniotic fluid or amniotic fluid with added phosphate has been employed to detect the presence of a phosphate-sensitive bacterial inhibitor in amniotic fluid near term. The time required for detection of the inhibitory activity is approximately 12 hours, in contrast to approximately 36 hours required for a previously reported technique. Application of this radiometric bioassay to demonstrate bacterial growth inhibition by amniotic fluid and physicochemical properties of the inhibitory activity yielded results comparable to those obtained with the older method of plate counts of viable bacteria. By the new technique it was possible to demonstrate that the inhibitory activity was phosephate sensitive, heat stable, inactivated by metal chelation, removed by bentonite, and present in a low-molecular-weight fraction of amniotic fluid.

Amniotic Fluid↗
PubMed1979

Cortical activation pattern during saccadic eye movements in humans: localization by focal cerebral blood flow increases.

Regional cerebral blood flow (rCBF) was measured in human subjects during saccadic eye movements by a 254-channel dynamic gamma camera. Focal rCBF increases were repeatedly observed in an area within the middle precentral and premotor regions which corresponds to the frontal eye field in humans. Our findings suggest that this region is localized between the "face" and "hand" areas in the precentral gyrus and extends anteriorly out of the primary motor strip into the adjacent premotor zone. In addition, saccades were associated with focal blood flow increases in regions corresponding to the frontal supplementary motor area and to the posterior temporooccipital visual association cortex. Similar changes in patterns of rCBF occurred during contralateral and ipsilateral horizontal saccades and also during vertical saccades, and did not differ between the right and left hemispheres. Focal rCBF increases were observed in the frontal eye field during several additional test procedures including ocular fixation and visual perception of a nonmoving target, auditory stimulation with closed eyes, and reading. It is presumed that these focal flow increases reflect increased localized neuronal activity and metabolic rate and therefore permit visualization of the cortical activation pattern associated with saccadic eye movements in humans.

Cerebral Cortex↗
PubMed1979

Additions to the myotonic dystrophy linkage group.

One hundred and thirty members of a family with 33 cases of Dystrophia myotonica (Dm) were tested for various genetic markers including Km, Jk, Lu and Se. All individuals tested were Lua negative, but many were heterozygous for the other markers. Except for two cases all patients with Dm were positive for Km3 and Jka and they were secretors. Assuming the genes are linked and that the order of the loci is Km, Jk, Lu, Se, Dm, then there were 22 meioses informative for Dm and in 10 of these a recombination must have occurred between two of the five loci. Looking at individual pairs of loci, there were no recombinations between Km and Jk in seven informative meioses, three recombinations out of 10 meioses informative for Jk/Se, no recombinations between Se and Dm in five informative meioses and three recombinations out of 12 meioses informative for Jk/Dm.

Female↗
PubMed1979

The separation of peptide hormone diastereoisomers by reverse phase high pressure liquid chromatography. Factors affecting separation of oxytocin and its diastereoisomers--structural implications.

Experimental conditions and parameters involved in high performance liquid chromatography (HPLC) separations of the peptide hormone oxytocin and seven of its diastereoisomers, namely [1-hemi-D-cystine]-, [2-D-tyrosine]-, [4-D-glutamine]-, [5-D-asparagine]-, [6-hemi-D-cystine-], [7-D-proline]-, and [8-D-leucine]-oxytocin, on reverse phase columns were investigated. The effects of solvent, pH, and salt concentration were studied. Using the solvent systems 10% tetrahydrofuran-ammonium acetate buffer or 18% acetonitrile-ammonium acetate buffer and the muBondapak C18 support, oxytocin was separated from each of its diastereoisomers under all conditions studied, but the order of elution of diastereoisomers was highly dependent on solvent and to a lesser extent on pH. Separations of the hormone and its diastereoisomers on reverse phase HPLC and on classical partition chromatography on Sephadex G-25 were compared. The results are discussed in terms of the interactions of the solute with the reverse phase column and the solvent system. Implications of these findings in terms of the different solution conformations of the peptides are discussed.

Amino Acid Sequence↗
PubMed1979

Regional blood flow in canine myocardium as determined by local washout of a freely diffusable radioactive indicator.

The aim of this study has been to examine the utility of the washout of a freely diffusable radioactive indicator as a measure of regional myocardial blood flow in open-chest anesthetized dogs. The method employed was direct intramyocardial injection of Xenon-133 followed by measurement of its gamma-radiation. The experimental washout curves show, after a short acceleration period, monoexponential washout of the indicator over two decades. We found indications of insignificant veno-arterial shunting by diffusion of the blood flow level measured, insignificant arterial recirculation of the indicator, and minimal radioactive contribution to precordial residue versus time curves arising from right heart or non-myocardial tissue. We suggest that diffusion equilibrium between the tissue in the counting field and the blood leaving it is maintained during the linear down slope of two decades of the clearance curve, and that local blood flow can be calculated from washout rate constant obtained from this part of the curve. The method employing intramyocardial injection of Xenon-133 was found to give the same results as atraumatic epicardial labelling indicating negligible effect of the injection trauma and supporting the validity of the local injection method using small volumes (2-10 microliter).

Animals↗
PubMed1979

A study of human leukocyte D locus related antigens in Graves' disease.

An association between Graves' disease and the human leukocyte antigen (HLA) system has previously been reported. The disease was more strongly associated with the HLA D locus antigen Dw3 than with HLA B8. Products of the HLA D locus are determined by the interaction of test cells with standard typing lymphocytes, a technically difficult procedure. Recently, it has been possible to type serologically for D locus related (DRw) specificities on peripheral bone marrow-derived (B) lymphocytes. Blood B lymphocytes from 50 unrelated controls and 41 patients with Graves' disease were typed for seven HLA DRw specificities. 28 patients with Graves' disease (68%) were positive for DRw3, in contrast to 14 controls (28%); whereas only 21 patients (50%) were HLA B8 positive, compared with 13 (26%) controls. Thus, positivity for DRw3 afforded a relative risk for Graves' disease of 5.5, whereas that for HLA B8 amounted to 3.0. Additionally, a family with multiple cases of Graves' disease in which the disease was previously shown to be inherited with the haplotype, was linked to DRw2, which suggests that the susceptibility to the disease was inherited in association with that antigen. Two HLA B/glyoxalase recombination events were observed in this family; in both instances HLA DRw followed HLA B. This study thus demonstrates that the disease susceptibility gene for Graves' disease is in strong linkage disequilibrium with DRw3; however, it may be associated with other DRw specificities and inherited within family units in association with them.

Alleles↗
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↗