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Biomedical subjects

J Nilsson

Publications and source records attributed to J Nilsson.

At least 289 records · Page 16Linked to original sources
PubMed1986

Follow-up of circulatory changes secondary to deep venous thrombosis with special regards to radionuclide tests.

The influence of circulatory changes, which are secondary to deep venous thrombosis (DVT) in the leg, on result of radionuclide tests was studied in eight patients. Strain gauge plethysmography, a radionuclide blood-pool test and phlebography were performed both in the acute phase and during recovery up to 6 months after the initial admission. Morphological and functional changes were correlated with results from repeatedly performed 99Tcm-plasmin tests, a test currently used for diagnosis of DVT. In the acute phase, the thrombotic leg showed an increase in pooled blood and, in the case of proximal thrombosis, also impaired venous outflow. During the 6-month follow-up complete recanalization was observed in three patients and partial recanalization in five. The circulatory changes were found to recover progressively and earlier than the morphological changes. The 99Tcm-plasmin test was pathological at admission in all patients. It was normalized in parallel with plethysmography and blood-pool test results, at a time when morphological recovery was still incomplete. These findings confirm that a positive 99Tcm-plasmin test reflects haemodynamic changes which are secondary to the DVT rather than a specific binding of the radiopharmaceutical to the thrombus. The 99Tcm-plasmin test was normalized from 1 to more than 26 weeks after an acute DVT. This finding is of practical importance when using radionuclide tests for evaluation of acute recurrent DVT.

Aged↗
PubMed1986

The frequency of digital and endoscopic examination of the rectum before radiological barium enema.

Doctor's delay in patients with rectal carcinoma is common with a frequency between 30% and 60%. The reason for delay has been supposed to be the neglectance to perform digital examination and rigid proctosigmoidoscopy in patients with symptoms of anorectal disease. Especially general practitioners have been blamed for a high percentage of this kind of doctor's delay. In this study 300 consecutive patients referred for radiological examination of the large bowel have been questioned if digital examination and rigid proctosigmoidoscopy have been performed by their referral doctor. The results show that in 19% of the cases neither digital nor proctosigmoidoscopic examination had been performed. Rigid proctosigmoidoscopy had been omitted in 44%. No statistical difference was observed in the frequency of digital examination between general practitioners (79%) and hospital doctors (84%). The low figures, both for digital examination and rigid proctosigmoidoscopy are probably causing many patients a delay in the diagnosis of a rectal carcinoma. Thus, a more intense evaluation in this area should be applied in the medical faculties and also at post graduate courses.

Adolescent↗
PubMed1985

Adenosine receptor-mediated changes in cyclic AMP production and DNA synthesis in cultured arterial smooth muscle cells.

The effects of adenosine and two analogs, L-phenylisopropyladenosine (L-PIA) and 5'-N-ethylcarboxamidoadenosine (NECA), on cAMP production and on platelet-derived growth factor (PDGF)-stimulated initiation of DNA synthesis in growth-arrested cultures of rat arterial smooth muscle cells (SMC) were studied. The intracellular cAMP concentration was dose-dependently enhanced by micromolar concentrations of adenosine and its analogs, with the potency order NECA greater than adenosine greater than L-PIA. The effect was antagonized, in a competitive manner, by the adenosine receptor antagonist 8-phenyltheophylline (8-PT). The stimulatory effect of adenosine was enhanced by 3 microM dipyridamole an adenosine-uptake blocker. DNA synthesis was inhibited in a parallel manner, showing the same potency order. The inhibition was antagonized by 8-PT. Forskolin, a diterpene with the ability to stimulate the catalytic unit of adenylate cyclase and thereby cAMP formation, potentiated the effects of micromolar concentrations of NECA and L-PIA. Forskolin, by itself, stimulated cAMP production and inhibited DNA synthesis. The forskolin-stimulated increase in cAMP was inhibited by L-PIA at nanomolar concentrations. L-PIA in the nanomolar concentration range also stimulated DNA synthesis when initiation was stimulated with suboptimal concentrations of PDGF. These findings suggest the presence of adenosine receptors of both the A1- and A2-subtype on SM-mediating bidirectional changes of cAMP and DNA synthesis.

Adenine↗
PubMed1985

Adult human arterial smooth muscle cells in primary culture. Modulation from contractile to synthetic phenotype.

Smooth muscle cells were isolated enzymatically from adult human arteries, grown in primary culture in medium containing 10% whole blood serum, and studied by transmission electron microscopy and [3H]thymidine autoradiography. In the intact arterial wall and directly after isolation, each smooth muscle cell had a nucleus with a wide peripheral zone of condensed chromatin and a cytoplasm dominated by myofilament bundles with associated dense bodies. After 1-2 days of culture, the cells had attached to the substrate and started to spread out. At the same time, a characteristic fine-structural modification took place. It included nuclear enlargement, dispersion of the chromatin and formation of large nucleoli. Moreover, myofilament bundles disappeared and an extensive rough endoplasmic reticulum and a large Golgi complex were organized in the cytoplasm. This morphological transformation of the cells was completed in 3-4 days. It was accompanied by initiation of DNA replication and mitosis. The observations demonstrate that adult human arterial smooth muscle cells, when cultivated in vitro, pass through a phenotypic modulation of the same type as arterial smooth muscle cells from experimental animals. This modulation gives the cells morphological and functional properties resembling those of the modified smooth muscle cells found in fibroproliferative lesions of atherosclerosis. Further studies of the regulation of smooth muscle phenotype and growth may provide important clues for a better understanding of the pathogenesis of atherosclerosis.

Adult↗
PubMed1985

The calcium antagonist nifedipine inhibits arterial smooth muscle cell proliferation.

Migration of smooth muscle cells from the media to the intima of the arterial wall and proliferation of intimal smooth muscle are major early events in the formation of an atherosclerotic lesion. The start of proliferation requires that the cells have passed through a modulation from contractile to synthetic phenotype and that they are stimulated with growth factors. Here, we have examined the effects of the calcium antagonist nifedipine on phenotypic modulation and growth of isolated rat arterial smooth muscle cells cultivated in vitro. The results indicate that micromolar concentrations of nifedipine slow down the rate of transformation of the cells from a contractile to a synthetic phenotype and inhibit initiation of DNA synthesis as well as cellular proliferation. The inhibitory effect on DNA synthesis was seen both in cells stimulated with whole blood serum and with purified platelet-derived growth factor. The results raise the possibility that nifedipine may be used to prevent atherogenesis and to inhibit progression of fibromuscular lesions by interfering with the proliferation of arterial smooth muscle cells.

Actins↗
PubMed1985

A new method to measure foot contact.

A new method to measure foot contact is described. It consists of a pressure sensitive transducer attached to one end of a flexible silicone rubber tube. A reliable indicator of foot contact is obtained with the tube glued to the outer perimeter of the sole of a shoe.

Humans↗
PubMed1985

The effect of lesions of the corpus callosum on finger localization.

Finger localization was studied in 10 cases of cerebral commissurotomy (four complete, six partial) and 24 normal subjects. Stimulation of one finger with the same hand responding produced ceiling performance in all subjects. Responses with the other hand (cross-localization) were 82% worse with full commissurotomy, 28% worse with the trunk of the corpus callosum sectioned, and 7% worse in the controls. The trunk of the corpus callosum normally transfers tactile information, but the splenium can subsume 50% of this function and tactile transfer with complete commissurotomy exceeded chance levels. The partially sectioned and normal male subjects showed a right-hand stimulation advantage for sequences. In both normals and partially sectioned subjects, cross-localization was poorest when mirror-image transfer of finger sequences was required, while spatial alignment of the fingers facilitated transfer. With complete commissurotomy, response hand orientation did not affect cross-localization. Thus the corpus callosum transmits the position of each hand between the hemispheres.

Adolescent↗
PubMed1985

Arterial smooth muscle cells in primary culture produce a platelet-derived growth factor-like protein.

Adult rat arterial smooth muscle cells (SMC) in primary culture modulate from contractile to synthetic phenotype. This process includes partial loss of myofilaments and formation of an extensive rough endoplasmic reticulum and a large Golgi complex. It gives the cells the ability to initiate DNA synthesis and actively proliferate when stimulated with serum or isolated growth factors. After a few divisions, growth becomes partly independent of exogenous mitogens and does not cease until multiple cell layers have been formed. Here, it is demonstrated that serum-free conditioned medium from primary cultures of adult rat arterial SMC contains a factor that initiates DNA synthesis in growth-arrested secondary cultures of SMC. The mitogenic activity was neutralized by antibodies to platelet-derived growth factor (PDGF), and no mitogenic activity occurred in conditioned medium from cultures pretreated with actinomycin D, excluding release into the medium of PDGF adsorbed to the plastic vessels during the initial culture in serum-containing medium. Exposure of human fibroblasts to samples of the conditioned medium at 4 degrees C inhibited subsequent binding of 125I-labeled PDGF. It was further shown that the SMC of the primary cultures were able to initiate DNA synthesis in a chemically defined medium lacking PDGF and other growth factors. During the early, most active, and partly autonomous growth phase, the SMC had a low binding capacity for 125I-labeled PDGF and responded but little to stimulation with exogenous PDGF. Later on, with increasing cell density and decreasing growth rate, the ability to bind and respond to exogenous PDGF increased. Taken together, the observations suggest that modulation of SMC from contractile to synthetic phenotype is accompanied by production of a PDGF-like protein and autocrine or possibly by mitogen-independent initiation of DNA synthesis. Functionally, this may be important during wound healing and in the development of atherosclerotic lesions.

Animals↗
PubMed1985

Changes in leg movements and muscle activity with speed of locomotion and mode of progression in humans.

Knowledge of adaptations to changes in speed and mode of progression (walking-running) in human locomotion is important for an understanding of underlying neural control mechanisms and allows a comparison with more detailed animal studies. Leg movements and muscle activity patterns were studied in ten healthy males (19-29 yr) during level walking (0.4-3.0 m X s-1) and running (1.0-9.0 m X s-1) on a motor-driven treadmill. Movements were recorded in the sagittal plane with a Selspot optoelectronic system. Recordings of EMG were made from seven different muscles of one leg by means of surface electrodes. Durations, amplitudes and relative phase relationships of angular displacements and EMG activity were analysed in relation to different phases of the stride cycle (defined by the leg movements). The durations of the entire stride cycle and of the support phase were found to decrease curvilinearly with velocity. Swing and support phase durations were linearly related to cycle duration in walking, and curvilinearly related in running. The characteristic occurrence of double support phases in walking was also seen in very slow running. Support length increased with speed up to about 1.2 m both in walking and running, but was longer in walking at the same velocity. Increases in net angular displacements were largest for hip movements and for knee flexion-extension during the swing phase in running. With increasing velocity a clear shift in relative rectus femoris activity occurred from knee extension to hip flexion. Gastrocnemius lateralis (LG) was co-activated with the other leg extensors prior to foot contact in running, whereas in walking LG was not turned on until later in the support phase. The ankle flexor tibialis anterior had its main peak of activity after touch-down in walking and before touch-down in running. The same basic structure of the stride cycle as in other animals suggests similarities in the underlying neural control. Human speed adaptation is distinguished primarily by an increase in both frequency and amplitude of leg movements and by a possibility of changing between a walking and a running type of movement pattern.

Adaptation, Physiological↗
PubMed1984

Prostaglandin E1 inhibits DNA synthesis in arterial smooth muscle cells stimulated with platelet-derived growth factor.

The effect of prostaglandins (PG) on initiation of DNA synthesis in arterial smooth muscle cells (SMC) stimulated with platelet-derived growth factor (PDGF) was examined. A concentration of 10 ng/ml PGE1 inhibited DNA synthesis, measured as autoradiographically labeled nuclei, by about 70%. Similar results were obtained with PGE2 and PGD2 but at concentrations 10-20 times higher, whereas PGF2 alpha lacked effect. The inhibitory action of the prostaglandins was restricted to the first 6 h of the lag phase. Treatment with PGE1 also raised the intracellular concentration of cyclic AMP, indicating that the inhibition may be mediated via changes in the levels of cyclic nucleotides.

Alprostadil↗
PubMed1984

Molecular cloning and characterization of the gene for Escherichia coli valyl-tRNA synthetase.

A ColE1 hybrid, pB2, carrying the structural gene for the valyl-tRNA synthetase, valS, and the pyrBI operon was isolated from the Clarke-Carbon collection. Strain GRB238 with a temperature-sensitive mutation in the valS gene showed a three-fold increase in valyl-tRNA synthetase activity after transformation with pB2. The valS gene was subcloned into pBR322 after partial Sau3A digestion of pB2. The new plasmid, pHOV1 had a 9.4-kb insert in pBR322 and cells carrying pHOV1 showed an eight-fold increase in specific valyl-tRNA synthetase activity. The localization and direction of transcription of valS in pHOV1 was determined by transposon-directed mutagenesis and analysis of protein synthesis in minicells. The valS gene was shown to be transcribed opposite to the direction of DNA replication, i.e., counterclockwise.

Amino Acyl-tRNA Synthetases↗
PubMed1984

Temperature-dependent retention of a tryptophan-operon-bearing plasmid in Escherichia coli.

Derivatives of plasmid pBR322 carrying the tryptophan operon are rapidly lost from a growing culture. The valS gene from Escherichia coli was combined with the tryptophan operon on a pBR322 derivative, pSGS21. In a thermosensitive valS mutant of E. coli K-12 host, plasmid pSGS21 was stably inherited for over 200 generations at temperatures nonpermissive for the chromosomal mutation. At 30 degrees C, a temperature at which the host valSts protein is functional, the plasmid was lost at a rate of 1.2% per cell generation.

Bacterial Proteins↗
PubMed1984

Phenotype modulation in primary cultures of arterial smooth-muscle cells. Dual effect of prostaglandin E1.

The effects of prostaglandin E1 (PGE1) on the phenotypic state of enzymatically isolated arterial smooth-muscle cells in primary culture were studied by transmission electron microscopy, thymidine autoradiography, and cell counting. Early in culture (day 0-2), PGE1 stimulated conversion of the cells from contractile (less euchromatic nucleus and cytoplasm dominated by myofilament bundles) to synthetic state (more euchromatic nucleus and cytoplasm dominated by cisternae of rough endoplasmic reticulum and a large Golgi complex). The rate of entrance of the cells into DNA synthesis and mitosis was also increased at this time. Later on (day 3-6), when the majority of the cells had entered synthetic state, PGE1 inhibited DNA synthesis and cellular proliferation. These observations indicate that the effect of prostaglandins on arterial smooth muscle is dual in nature and dependent on the state of differentiation of the cells.

Alprostadil↗
PubMed1984

Comparison between 99Tcm-porcine plasmin and 99Tcm-labelled erythrocytes in diagnosis of deep vein thrombosis.

In 20 patients with suspect deep venous thrombosis (DVT), scintillation detector measurements were performed over each leg during the first 60 min after intravenous injection of 99Tcm-porcine plasmin. Thereafter, 99Tcm-labelled autologous erythrocytes were injected i.v. and repeat measurements were performed. Finally, scintillation camera images of both legs were obtained. Phlebography was used as a reference method. A close relationship (P less than 0.01) was found between the scintillation detector measurements, both in patients with DVT (n = 11) and in patients without DVT (n = 9). Thus, 99Tcm-plasmin is not specifically bound to the thrombus. Rather the clinical utility of the test depends mainly on circulatory changes secondary to the thrombus. Scintillation camera images of 99Tcm-erythrocytes in the legs were not useful for diagnosis of DVT in the calves but showed a high specificity for DVT in the popliteal and femoral veins.

Adult↗
PubMed1984

Trunk movements in human locomotion.

Trunk movements in the frontal and sagittal planes were studied in 10 healthy males (18-35 yrs) during normal walking (1.0-2.5 m/s) and running (2.0-6.0 m/s) on a treadmill. Movements were recorded with a Selspot optoelectronic system. Directions, amplitudes and phase relationships to the stride cycle (defined by the leg movements) were analyzed for both linear and angular displacements. During one stride cycle the trunk displayed two oscillations in the vertical (mean net amplitude 2.5-9.5 cm) and horizontal, forward-backward directions (mean net amplitude 0.5-3 cm) and one oscillation in the lateral, side to side direction (mean net amplitude 2-6 cm). The magnitude and timing of the various oscillations varied in a different way with speed and mode of progression. Differences in amplitudes and timing of the movements at separate levels along the spine gave rise to angular oscillations with a similar periodicity as the linear displacements in both planes studied. The net angular trunk tilting in the frontal plane increased with speed from 3-10 degrees. The net forward-backward trunk inclination showed a small increase with speed up to 5 degrees in fast running. The mean forward inclination of the trunk increased from 6 degrees to about 13 degrees with speed. Peak inclination to one side occurred during the support phase of the leg on the same side. Peak forward inclination was reached at the initiation of the support phase in walking, whereas in running the peak inclination was in the opposite direction at this point. The adaptations of trunk movements to speed and mode of progression could be related to changing mechanical conditions and different demands on equilibrium control due to e.g. changes in support phase duration and leg movements.

Adaptation, Physiological↗