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Biomedical subjects

K Sandberg

Publications and source records attributed to K Sandberg.

At least 109 records · Page 6Linked to original sources
PubMed1984

Cholinergic lesion of the striatum impairs acquisition and retention of a passive avoidance response.

Significant impairments in the acquisition and retention of a step-down passive avoidance task were found in rats with striatal lesions induced by the cholinergic neurotoxin AF64A. No significant differences between control and AF64A-injected rats were found in sensitivity to electric shock or in various measures of spontaneous locomotor activity. Striatal choline acetyltransferase (CAT) activity was significantly decreased in AF64A-treated rats compared with controls, whereas glutamic acid decarboxylase (GAD) activities were not. Furthermore, there were no significant differences between groups in activities of CAT and GAD in either the cortex or the hippocampus, results that support the specificity of the lesion to the striatum. The passive avoidance deficits found in these rats after intrastriatal injection of AF64A support a role for the striatal cholinergic system in complex behavioral processes.

Animals↗
PubMed1984

Genetic linkage in the horse. II. Distribution of male recombination estimates and the influence of age, breed and sex on recombination frequency.

In the present study an extensive amount of data, comprising more than 30,000 offspring in total, was analyzed to evaluate the influence of age and sex on the recombination frequency in the K-PGD segment of the equine linkage group (LG) I and the influence of age, breed and sex on recombination in the Al-Es segment of LG II. A highly significant sex difference is reported for both segments. Male and female recombination values in the K-PGD segment were estimated at 25.8 +/- 0.8 and 33.3 +/- 2.5%, respectively. Similarly, recombination was less frequent in the male (36.6 +/- 0.7%) than in the female (46.6 +/- 1.2%) in the Al-Es segment. Comparison of data from two Swedish horse breeds revealed no significant breed differences in either sex for recombination in the Al-Es segment. No evidence of an age effect was found in any segment or sex. The distribution of individual male recombination estimates was also investigated, and a significant heterogeneity among stallions was revealed in the K-PGD segment. The results are discussed in relation to previous studies on factors affecting recombination in mammals.

Age Factors↗
PubMed1984

Two-dimensional electrophoresis of horse serum proteins: genetic polymorphism of ceruloplasmin and two other serum proteins.

Two-dimensional agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis of horse serum proteins revealed genetic polymorphism of ceruloplasmin (Cp) and two unidentified serum proteins tentatively designated serum protein 1 (SP1) and serum protein 2 (SP2). Family data were consistent with the hypothesis that the observed Cp and SP1 phenotypes were each controlled by two codominant, autosomal alleles. The three common SP2 phenotypes were shown to be controlled by two codominant, autosomal alleles. Population data and limited family data indicated the occurrence of two additional SP2 alleles. Altogether more than 600 horses representing 13 different breeds were typed for Cp, SP1 and SP2, and allele frequency estimates were calculated. SP2 was highly polymorphic in all breeds studied whereas SP1 and Cp showed quite low degrees of polymorphism. SP1 polymorphism was observed in seven breeds while Cp polymorphism was observed only in the Icelandic toelter horse breed.

Alleles↗
PubMed1984

Analysis of alveolar ventilation in the newborn.

Twelve healthy term infants were examined at the median ages of 2 1/2 and 26 hours. Their alveolar ventilation, efficiency of ventilation, functional residual capacity, and lung nitrogen elimination patterns were studied by means of a computerised nitrogen wash out method. The results showed that alveolar ventilation and functional residual capacity increased over the period studied. At the same time effective dead space decreased leaving minute ventilation unchanged. Distribution of ventilation did not change.

Aging↗
PubMed1984

Calculation of lung volume in newborn infants by means of a computer-assisted nitrogen washout method.

A clinically adapted method for the calculation of the functional residual capacity in newborn infants has been developed. The method is based on a multiple breath nitrogen washout test, during which the ventilatory air flow and the nitrogen concentration signals are sampled by a minicomputer, which also performs the calculations. The ventilatory air flow is measured by a pneumotachometer connected to a face-out volume displacement body plethysmograph, and the nitrogen concentration by a nitrogen analyzer. The functional residual capacity volume is calculated from the sampled signals by adding the expired nitrogen volumes during each expiration, and finally dividing this sum by the initial alveolar nitrogen concentration. Before the calculations, the sampled signals are adjusted regarding nitrogen analyzer delay and plethysmograph characteristics. The method presented is designed to minimize the test equipment influence on the baby's respiration and also to inhibit the necessity of pneumotachometer compensations normally connected with washout methods. Furthermore, the calculated breath-by-breath values of end-expiratory nitrogen concentration, nitrogen volume, inspired and expired tidal volume, are stored on disk for further analysis and resimulation of the test. The method has been tested on a mechanical lung model and on washouts from healthy newborn infants. The model tests indicate that the accuracy and the reproducibility of the method are good, and the results from the infants are in good agreement with previously obtained results.

Computers↗
PubMed1983

Genetic linkage between the loci for phosphohexose isomerase (PHI) and a serum protein (Xk) in horses.

Genetic linkage between the equine loci for phosphohexose isomerase (PHI) and serum Xk protein was demonstrated by means of segregation data from three sire families. The recombination frequency was estimated from pooled data to be 0.23 +/- 0.02; a significant heterogeneity between sires for estimates of the recombination frequency was observed. No indication of linkage was detected between Xk and 14 other blood marker loci. Linkage between the Xk locus and the locus for soluble malic enzyme (ME1) has recently been reported in horses. An equine linkage group designated LG IV comprising the three loci ME1, PHI, and Xk has thus been established. The possibility that the linkage between PHI and Xk is homologous to the linkage between the loci for PHI and a serum postalbumin (PO-2) in pigs was discussed.

Animals↗
PubMed1983

IgE-binding factors from mouse T lymphocytes. I. Formation of IgE-binding factors by stimulation with homologous IgE and interferon.

Incubation of normal mouse spleen cells with homologous IgE resulted in the formation of soluble factors that inhibited rosette formation of mouse Fc epsilon R+ cells with IgE-coated ox erythrocytes. The soluble factors could be absorbed with mouse or rat IgE coupled to Sepharose and recovered from the beads by acid elution. However, the factors had no affinity for either human IgE or mouse IgG. The IgE-binding factors were derived from T cells. Production of the factors required Lyt1+ T cells and Fc gamma R+ cells, which suggests that the factors are derived from Fc gamma R+ Lyt 1+ T cells. The molecular size of IgE-binding factors was approximately 15,000 daltons. When IgE-binding factors were formed by BALB/c spleen cells, nearly one-half of the factors had affinity for lentil lectin, and the remaining half of the factors failed to bind to the lectin. The proportion of the two species of IgE-binding factors differed depending on mouse strains. The majority of the factors formed by B6D2F1 spleen cells had affinity for lentil lectin, but those formed by SJL spleen cells failed to bind to the lectin. The IgE-binding factors were also induced by incubation of normal spleen cells with polyinosinic-polycytidylic acid (pI:pC). The nucleotide stimulated splenic adherent cells to form "inducers" of IgE-binding factors, which in turn induced normal lymphocytes to form IgE-binding factors. The inducers of IgE-binding factors were inactivated (or neutralized) by antibodies specific for mouse Type I interferon. It was also found that purified mouse beta interferon could induce the formation of IgE-binding factors. IgE-binding factors induced by pI:pC consisted of two different molecules: one had a m.w. of 15,000 daltons, and another had a m.w. of between 40,000 and 60,000 daltons.

Animals↗
PubMed1981

Relation between blood resistivity and hematocrit in fresh human fetal blood.

This study determined the relation between hematocrit and resistivity of fetal blood and compared it with values obtained in similar studies on adult blood. Both exponential and Maxwell-Frick-estimated relationships were calculated and compared. The results indicate that there is no significant difference between resistivity in adult and fetal blood. The best relation between blood resistivity and fetal hematocrit is obtained by using the Maxwell-Frick estimated curve calculated in the following manner: (formula: see text).

Adult↗
PubMed1981

Formation of IgE binding factors by human T lymphocytes.

Peripheral blood mononuclear cells from ragweed-sensitive individuals formed soluble factors that inhibited rosette formation of Fc epsilon receptor (+) cells with IgE-coated ox erythrocytes when the cells were incubated with ragweed antigen E and human IgE. Either antigen E alone or IgE alone failed to induce the formation of the rosette inhibiting factors. Two-way mixed lymphocyte culture from 2 normal individuals followed by incubation of the activated lymphocytes with IgE induced the formation of the rosette-inhibiting factor. Normal human mononuclear cells cultured in the presence of T cell growth factor (TCGF) formed the soluble factor when they were incubated with IgE. The rosette-inhibiting factor in culture filtrates was specifically absorbed with IgE-coupled Sepharose and was recovered from the beads by elution at acid pH, indicating that the soluble factors have affinity for IgE. Because the lymphocytes cultured with TCGF were mostly T cells and contained neither B cells nor monocytes, it appears that the IgE-binding factors are derived from T cells.

Binding Sites, Antibody↗
PubMed1979

Genetic polymorphism and close linkage of two alpha 1-protease inhibitors in horse serum.

Two-dimensional electrophoretic analysis of horse serum proteins was done by a first-dimension separation in agarose gel (pH 5.4) followed by a second-dimension separation in horizontal polyacrylamide gel (pH 9.0). This method resulted in improved and reproducible separation of many alpha-globulins. Two groups of alpha 1-globulins, designated Pi1 and Pi2, were found to be protease inhibitors. Preliminary studies indicated that Pi1 and Pi2 proteins differed from each other in molecular weight and in protease inhibiting spectra. Extensive polymorphism was observed for both these proteins. Family data supported the hypothesis that Pi1 and Pi2 types were controlled by autosomal codominant alleles. For both Pi1 and Pi2 systems, most of the homozygous types showed two fractions each while the heterozygous types had 4 fractions. Six Pi1 and five Pi2 alleles were observed in two breeds of Swedish horses. Complete genetic linkage was observed for Pi1 and Pi2 loci as no recombinant type was observed in 40 informative matings studied.

Alleles↗
PubMed1978

Axial ligand effects on myoglobin stability.

Reversible guanidine hydrochloride denaturation has been applied to obtain the first quantitative estimate of ligand-induced changes in hemoprotein conformational free energy. It is found that strong field (low spin) complexes, e.g. cyanometmyoglobin (MbCN) and azido metmyoglobin (MbN3), are 1.0 +/- 0.1 kcal/mol more stable than the high spin analogs aquometmyoglobin (MbH2O) and fluorometmyoglobin (MbF). This observed stability increment is essentially independent of the model chosen for data analysis. These results demonstrate the value of denaturation titration in measuring the stabilization of hemoprotein conformation by ligand binding. The denaturation of MbN3 appears complex. This complexity may be quantitatively accounted for by considering spin state equilibria. Applying this correction, MbCN and MbN3 have essentially the same stability in spite of steric differences in the two proteins. This result implies metal spin state is more important than ligand stereochemistry in determining the conformational free energy of myoglobin.

Azides↗
PubMed1978

Genetic polymorphism of the vitamin D binding protein and another post-albumin protein in horse serum.

Horizontal polyacrylamide gel electrophoreses, on 10% separation gel, of horse serum revealed polymorphism of the vitamin D binding protein (Gc protein) and another post-albumin protein (Pa). Family data supported the hypothesis that Gc and Pa types were controlled by autosomal codominant alleles. For both Gc and Pa proteins, the homozygous types showed a single fraction while the heterozygous type had two fractions. Pa types were found to be identical to the post-albumin types reported earlier by starch gel electrophoresis. Two Gc alleles, GcF and GcS, and three Pa alleles, Pa D, Pa F and Pa S, were observed in samples from Swedish (four breeds), Lipizzaner and Arab horses. The frequency of the more common allele at the two loci, i.e. GcF and PaF, ranged from 0.72-0.93 and from 0.58-0.99, respectively, in the different breeds studied. Plasma samples showed an extra protein fraction near the GcS fraction and thus were found unsuitable for Gc typing.

Alpha-Globulins↗
PubMed1978

Close linkage between the albumin and Gc loci in the horse.

Evidence for close linkage between the structural loci for albumin and Gc protein in the horse was presented. A recombination frequency (c) of 0.009 +/- 0.006 (95% confidence limits: 0.001 less than c less than 0.032) was estimated. These results were based on a study of a large sire family comprising 223 offspring from informative matings. No evidence of linkage disequilibrium was observed in one horse population studied.

Alleles↗