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Biomedical subjects

G Andersson

Publications and source records attributed to G Andersson.

At least 253 records · Page 14Linked to original sources
PubMed1988

Sequence and regulation of two growth-hormone-controlled, sex-specific isozymes of cytochrome P-450 in rat liver, P-450(15)beta and P-450(16)alpha.

Full length cDNA clones for the sexually differentiated rat liver cytochrome P-450 isozymes 15 beta and 16 alpha have been isolated and sequenced. The deduced amino acid sequence of P-450(15)beta is 66% homologous to that of P-450(16)alpha. Furthermore, either of these two cytochromes has a homology of about 50% with the major phenobarbital inducible form, cytochrome P-450b, while the homology with the major carcinogen inducible form, cytochrome P-450c, is less than 30%. Also, the homology of these two sex-dependent cytochromes with the developmentally regulated cytochrome P-450 isozymes f and PB-1 is about 70%. Therefore, it is concluded that P-450 isozymes 15 beta, 16 alpha, f, and PB-1 represent a subfamily within the phenobarbital related cytochrome P-450 gene family. Growth hormone is known to be a major determinant for expression of P-450(15)beta and P-450(16)alpha and the time course of this induction was studied at the pretranslational level. Continuous infusion of GH to hypophysectomized male rats caused an induction of P-450(15)beta mRNA after 6 days of treatment while intermittent injections had no effect during that time course. The opposite was found to be the case for P-450(16)alpha mRNA where no effect was observed following continuous administration of GH, whereas intermittent injections caused an induction after 2 days of treatment.

Amino Acid Sequence↗
PubMed1987

Class II genes of the human major histocompatibility complex. Organization and evolutionary relationship of the DR beta genes.

The genes of the polymorphic HLA-DR molecules are located within the human major histocompatibility complex. We have studied the HLA-DR genes of an HLA homozygous individual typed to be DR4, Dw4, and DRw53. Fourteen cosmid and phage clones from genomic libraries were isolated and grouped into three clusters comprising a total of 165 kilobases. These clusters contain four DR beta genes. Nucleotide sequence determination showed that two of the genes encode beta chains that carry the DR4 and DRw53 specificities, respectively, while the other two genes are presumably pseudogenes. Comparisons of the nucleotide sequences of all four DR beta genes of the DR4 haplotype show that the genes are extensively similar, approximately 90% in both exons and introns. All four genes are equally similar to each other. These observations are consistent with the notion that the genes arose by duplications that were followed by homogenization through gene conversion. The existence of more than one DR beta gene homologue but only a single DR alpha gene homologue in mouse, rabbit, and cattle suggests that the DR beta gene duplications occurred at or early during mammalian speciation.

Base Sequence↗
PubMed1987

Class II genes of the human major histocompatibility complex. Comparisons of the DQ and DX alpha and beta genes.

The human major histocompatibility complex, HLA, contains the genes of several class II molecules. We present here the molecular maps of the DQ and DX subregions and analyze the sequences of the polymorphic DQ alpha and DQ beta genes as well as the DX alpha and DX beta genes. The DQ alpha and DQ beta genes are oriented in opposite directions, approximately 12 kilobases apart. The DX alpha and DX beta genes are similarly oriented about 8 kilobases. The exon-intron organizations of the DQ alpha and DX alpha genes are analogous to those of other class II alpha genes. Comparison of the DQ alpha gene sequence to three DQ alpha cDNA clones shows that amino acid replacements are predominantly located between residues 45 and 80 in the amino-terminal domain. Analysis of the frequency of silent and replacement substitutions indicates that there is little selection against replacements in DQ alpha first domains. The exons encoding the second domains of DQ alpha and DX alpha are virtually identical, suggesting that a gene conversion event has occurred between these genes. The DX beta gene is very similar to the DQ beta gene but differs in the cytoplasmic portion. The DX beta gene contains a separate exon of 24 nucleotides encoding the core of the cytoplasmic tail. This exon is not expressed in the DQ beta genes due to a nonfunctional splice junction. Comparison of the number of nucleotide substitutions in the DQ beta first and second domain exons suggests that little or no phenotypic selection acts on the first domain whereas the second domain is under strong selection.

Amino Acid Sequence↗
PubMed1987

Lumbar trunk muscle use in standing isometric heavy exertions.

A study was conducted to see whether a biomechanical model previously validated for predicting the lumbar spine internal loads imposed by the performance of easy and moderately strenuous physical tasks was also adequate for predicting loads imposed by heavy exertions. Lumbar trunk muscle myoelectric activities were measured in 10 healthy young adult men performing a variety of less strenuous and more strenuous tasks while standing upright, and these were compared to the lumbar muscle contraction magnitudes predicted by the model. For the less strenuous tasks, measured activities and predicted forces showed strong linear correlations, confirming the validity of the model at those load levels. Model predictions for the more strenuous tasks were often found to be inadequate. Contrary to model-incorporated assumptions, substantial antagonistic muscle contractions sometimes occurred, intraabdominal pressurization may sometimes have contributed substantially to the maintenance of structural equilibrium, and the ligamentous tissues of the trunk seemed sometimes to develop substantial passive resistances to bending and twisting moments.

Adult↗
PubMed1987

Inferior olive excitability after high frequency climbing fibre activation in the cat.

1. Climbing fibre responses (CFRs) were evoked by limb nerve stimulation and recorded from the cerebellar surface in barbiturate anaesthetized cats. Climbing fibres were activated at frequencies of usually 2.5-7.5 Hz for periods of 15-30 s, after which the stimulation frequency was reduced to below 1 Hz. 2. The high-frequency stimulation induced a strong depression of CFR-amplitude, lasting up to 60 s. The magnitude of this depression was dependent on both the frequency and the duration of the high-frequency stimulation. 3. The depression occurred in the c1, c2 and c3 zones of the pars intermedia and in the x zone in the vermis but not in the b zone in the vermis. 4. Recordings of olivary reflex responses demonstrated that the depression occurred in the inferior olive. 5. It is suggested that the inhibition of the inferior olive occurs because the high-frequency stimulation leads to a disinhibition of neurones in the interpositus nucleus which inhibit the olivary neurones.

Afferent Pathways↗
PubMed1987

Activity of Purkinje cells and interpositus neurones during and after periods of high frequency climbing fibre activation in the cat.

The activity of cerebellar Purkinje cells and interpositus neurones was recorded during and after periods of high frequency (2.5-7.5 Hz) climbing fibre activation in barbiturate-anaesthetized cats. 1. During the high frequency conditioning stimulation, the Purkinje cell simple spike (SS) firing was initially silenced in all zones studied. After a few seconds, the SS reappeared and the frequency increased to well above that of the control level after approximately 10 s. Thereafter, the SS rate started to decline so that, after 15-20 s, the Purkinje cells fired no more SS. This SS silence lasted up to 60 s, whether or not the stimulation was continued. 2. The Purkinje cells responded with a complex spike (CS) to every stimulus. If the high-frequency stimulation lasted for at least 15 s, the spontaneous CS discharge of the Purkinje cells in the c1, c2, and c3 zones was suppressed after the conditioning stimulation had ended. This suppression lasted for approximately the same length of time as the SS silence. In the b zone, however, no CS suppression was observed. 3. Interpositus neurones displayed an increased discharge rate after periods of conditioning stimulation, thus displaying a mirror image of the Purkinje cell SS firing. 4. The behaviour of the neurones agrees well with the behaviour predicted by an hypothesis of the olivo-cerebello-olivary loop (Andersson and Hesslow 1987). 5. The results suggest that the cerebello-olivary projection is topographically organized and matches the microzonal organization in the olivo-cerebellar projection.

Afferent Pathways↗
PubMed1987

Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms.

Standardised questionnaires for the analysis of musculoskeletal symptoms in an ergonomic or occupational health context are presented. The questions are forced choice variants and may be either self-administered or used in interviews. They concentrate on symptoms most often encountered in an occupational setting. The reliability of the questionnaires has been shown to be acceptable. Specific characteristics of work strain are reflected in the frequency of responses to the questionnaires.

Journal Article↗
PubMed1987

Responsiveness in diffuse versus local cutaneous leishmaniasis is due to parasite differences.

Leishmania aethiopica infection results in two main clinical entities, diffuse disease (DCL) and localized ulcers (LCL). The lack of reactivity to leishmanial antigens has been attributed, among other things, to some inherent immunological defect of the host or considered as a consequence of the initial site of infection. Properties unique to the infecting parasite have been said to contribute little if anything to the differences between DCL and LCL found in the same areas of Ethiopia. Data are given to show that infected individuals respond by higher production of IL-2 to antigens from LCL isolates (lcl antigen), than to antigens derived from DCL isolates (dcl antigen). Furthermore, dcl antigen induced less gamma interferon from lymphocytes of all individuals tested than did lcl antigen. Lymphocytic proliferation of cells from control individuals working in the endemic area was higher in response to lcl isolates than to dcl isolates. These findings suggest that some differences in the parasites may contribute to the clinical outcome of infection with L. aethiopica.

Adult↗
PubMed1987

Lack of casual relationship between medullary blood congestion and tubular necrosis in postischaemic kidney damage.

The effect of haemodilution on medullary blood congestion and tubular necrosis was investigated in the rat kidney. Male Sprague-Dawley rats were subjected to 60 min of unilateral, kidney ischaemia and 24 h of reperfusion. Haemodilution was performed by replacing blood by homologous serum and was done either before induction of ischaemia or during the ischaemic period. Cellular necrosis was evaluated morphologically by a histochemical staining for calcium and a dye-exclusion test. Trapped erythrocytes were visualized by the DAB reaction. It was found that haemodilution could totally prevent medullary congestion. In spite of this, the extent and distribution of necrotic tubular cells in the outer stripe of the outer medulla were the same whether the animal was subjected to haemodilution or not. Our results strongly suggest that the cellular necrosis and the medullary congestion are two separate phenomena occurring at the same time, but without a causal relationship to each other.

Acute Kidney Injury↗
PubMed1987

Complex spikes in Purkinje cells in the lateral vermis (b zone) of the cat cerebellum during locomotion.

1. Complex spikes (c.s.s) due to climbing fibre input were recorded from forty-one Purkinje cells in the lateral part of the vermis (i.e. the b zone) of lobule V of the cerebellum in cats walking on a moving belt or a horizontal ladder. Most cells were near the tips of the folia making up the lobule and some were shown by antidromic invasion to project to the ipsilateral lateral vestibular nucleus. In all cells c.s.s. could be evoked through mechanical stimuli delivered manually to the neck and/or trunk and/or the limb girdles and/or the proximal parts of the limbs. 2. During walking c.s.s. occurred at rates which ranged in different cells from 0.8 to 2.55/s (i.e. ca. 0.8 to 2/step). When activity was averaged across many successive steps the probability of c.s. occurrence was never completely constant throughout the step cycle, but no tendency was detected for c.s.s to recur at any precisely fixed time during the cycle. 3. When ladder locomotion was perturbed because a rung underwent an unexpected 2 cm descent when stepped on, some cells generated a c.s. at short latency in a proportion of trials. Such responses were well time-locked to the onset of rung movement but not to its cessation (which they often preceded). 4. For perturbations of either forelimb the earliest displacement-related c.s. occurred in different cells between 40 and 64 ms after the onset of rung movement. In different cells c.s.s occurred in from one out of five to three out of four perturbed steps (mean ca. two out of five steps). Eight out of seventeen cells responded to perturbation of the forelimb ipsilateral to the cell and five out of ten responded to contralateral perturbations. 5. Perturbation of the ipsilateral hind limb was accompanied by c.s.s in four out of nine cells and latency was usually longer (by ca. 30-40 ms). One cell showed a decrease in the probability of c.s. occurrence. Insufficient data were obtained for a systematic study of responsiveness to perturbation of the contralateral hind limb. 6. Cells showed different patterns of limb specificity, responding to perturbation of one, two or all of the three limbs studied. In total, c.s.s accompanied perturbation of at least one limb in thirteen out of twenty cells studied (65%).(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

The response of the seated human to sinusoidal vibration and impact.

Low back pain has been shown to occur more frequently among vehicle drivers than in representative control groups. Thus the response of the human to vibration and impact is of interest. This study investigated the response of the spine to both impact and sinusoidal excitation in either a relaxed or erect seated posture. The sinusoidal testing apparatus used was a resonating system consisting of two parallel wooden beams, simply supported, and the impact testing apparatus a bearing-guided, spring-suspended platform, struck from below. Ten subjects (5 males, 5 females) were evaluated using both methods. Transfer functions were compared at 2-4 Hz, 4-8 Hz and 8-16 Hz intervals using a sign test. Although in 24 comparisons of either test method (vibration or impact) or posture (erect or relaxed) where eleven showed differences significant at the p less than .05 level, only 2 out of 24 comparisons were the differences distinct enough to be significant (at the p less than .01 level). Both of these latter differences were due to test method while the subjects were sitting erect. In those instances where there were no significant differences due to test method, the impact method may be a viable replacement for the vibration test method. Where the levels of significance are higher (p less than .01 or p less than .05), further study of the magnitude of the differences is indicated and may reveal further insight into the seated individual as a system.

Adolescent↗
PubMed1987

Interleukin 2 and gamma interferon production, interleukin 2 receptor expression, and DNA synthesis induced by tularemia antigen in vitro after natural infection or vaccination.

The T-cell response induced by Francisella tularensis antigen in sensitized subjects was characterized in vitro by measuring DNA synthesis in whole-blood and mononuclear cell cultures, interleukin 2 (IL-2) and gamma interferon (IFN-gamma) production, and IL-2 receptor expression. Correlations between these variables were estimated. The strengths of the responses were compared in 21 subjects naturally infected 2 years ago, 6 subjects vaccinated 5 to 6 years ago, and 13 control subjects with no history of infection or vaccination. Subjects with a history of natural infection synthesized more DNA in both whole-blood and mononuclear cell cultures, secreted more IL-2 and IFN-gamma, and expressed more IL-2 receptors than control subjects did. All these responses differed highly significantly (P less than 0.001) from those of the control subjects. The vaccinees exhibited somewhat lower responses than the naturally immunized subjects did, but the vaccinees could be distinguished from the control subjects by their DNA synthesis, receptor expression, and IFN-gamma production (P less than 0.01 to 0.001). The vaccinees showed a lower response, in terms of DNA synthesis and IL-2 secretion (P less than 0.05), than the infected group did but responded in a manner similar to that of this group, with respect to receptor positivity and IFN-gamma secretion (P greater than 0.10). The correlations between all the T-cell functions were good, with highly significant correlations (P less than 0.001) between whole-blood DNA synthesis and IL-2 and IFN-gamma secretion and between the two lymphokines (P less than 0.001). The results not only increase our knowledge of the T-cell response to tularemia antigen but also give an alternative approach to DNA synthesis measurement for the quantitation of T-cell responses. The results for the low-responding sensitized subjects seem to indicate that the parameters were comparable in sensitivity.

Adult↗
PubMed1986

Retrograde axonal transport of asialoglycoproteins in mouse trigeminal neurons in vivo and in rat dorsal root ganglia neurons in vitro.

Different terminal sugars of the glycoprotein orosomucoid were exposed by sequential glycosidase digestions. The orosomucoid and its different derivatives were conjugated to horseradish peroxidase by a two-step glutaraldehyde coupling procedure, injected into the snout of 12-day-old mice or exposed to dorsal root ganglia neurons from embryonic rats, cultivated in a two chamber system. A marked increase in transport of the conjugates in the trigeminal and dorsal root ganglia neurons was observed histochemically after removal of sialic acid, exposing galactose as the terminal sugar. Quantitative hydrolysis of galactose residues resulted in reduced uptake. The data suggest the presence of a galactose-recognition molecule in the axon-terminal membrane, involved in retrograde axonal transport.

Animals↗
PubMed1986

Occurrence of athletic injuries in voluntary participants in a 1-year extensive newspaper exercise campaign.

In 1977 the newspaper Ostgötacorrespondenten (Corren) started a 1-year campaign for better health. The campaign was called "Piggare med Corren" (get fit with the Corren) and included antismoking, dietary, and exercise components. It was given widespread publicity in the newspaper. The purpose of the study was to examine the extent of self-reported exercise injuries in volunteers who diligently participated in a newspaper campaign. Information was collected from questionnaires sent to the most persistent participants after the campaign; 60% answered the questionnaire. An analysis of the dropouts showed that they had not started to exercise to the same extent as the others. Only 5% said that they had not exercised before the campaign; 6.7% reported that they were injured in connection with their exercising during the campaign in such a way that they had to interrupt their exercise. Thirty-seven persons had called a doctor and 19 persons were reported sick during for an average of 1 month because of the exercise injuries. There were significantly more regular exercisers who had been highly active before the campaign among those who had been injured compared with those who were not injured.

Adult↗