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Biomedical subjects

H Nilsson

Publications and source records attributed to H Nilsson.

At least 91 records · Page 5Linked to original sources
PubMed1994

Magnesium sulphate infusion decreases circulating calcitonin gene-related peptide (CGRP) in women with primary Raynaud's phenomenon.

The effects of two different vasodilating agents (MgSO4 infusion and the calcium antagonist nifedipine) on circulating levels of calcitonin gene-related peptide (CGRP) were studied in 12 women with pronounced primary Raynaud's phenomenon (PRP) and in 12 healthy females. There were no significant differences with regard to basal levels of circulating CGRP between women with PRP and the control group; median 15.5 (range 10-48) vs. 14 (range 10-69) pmol l-1, respectively. However, treatment with MgSO4 infusion significantly decreased circulating CGRP in women with PRP only from median 15.5 (range 10-48) to 10 (range 10-110) pmol l-1) (P < 0.05). On the other hand 14 days of treatment with nifedipine did not affect circulating CGRP in either of the investigated groups. Erythrocyte magnesium (ery-Mg) levels increased significantly after MgSO4 infusion in women with PRP (2.43 +/- 0.13 vs. 2.52 +/- 0.15 mmol l-1, P < 0.05) but not in the controls (2.51 +/- 0.24 vs. 2.57 +/- 0.28 mmol l-1, ns). In conclusion, the decrease of circulating CGRP after MgSO4 infusion in women with PRP provides further evidence that magnesium plays a significant role in the pathophysiology of PRP.

Adult↗
PubMed1994

Rhythmic contractions in isolated small arteries of rat: role of K+ channels and the Na+,K(+)-pump.

Small mesenteric arteries from Wistar rats display rhythmic tension oscillations, associated with oscillations in membrane potential, when stimulated with noradrenaline. The purpose of this study was to investigate the role of potassium conductance and Na+, K(+)-pump activity in the generation of these oscillations. The effect on the rhythmic contractions of several agents, interacting with K+ channels, was studied. Application of apamin, pinacidil or glibenclamide did not affect the rhythmic activity. Tetraethylammonium (TEA) increased the frequency of the rhythmic contractions, while application of 4-aminopyridine (4-AP) increased the amplitude by approximately 50%, with no changes in frequency. Ba2+, on the other hand, impaired the rhythmic contractions or converted them to irregular oscillations in the presence of functional endothelium, but did not affect oscillations in endothelium-denuded vessels. Ouabain or exposure to K(+)-free solution, procedures known to inhibit the Na+,K(+)-pump, abolished the rhythmic contractions. This effect was immediate, suggesting that it was due to elimination of the electrogenic action of the Na+,K(+)-ATPase, rather than to a change in intracellular ion concentrations. Exposure to an extracellular potassium concentration of more than 20 mM also inhibited the oscillation activity. The results suggest that the oscillations are not caused by, but may be modulated by, variations in potassium conductance. The Na+,K(+)-pump seems to play an important role in the generation of rhythmic contractions in these vessels.

4-Aminopyridine↗
PubMed1994

Rhythmic contractions of isolated, pressurized small arteries from rat.

The present study was undertaken to examine the influence of transmural pressure on vasomotion and to determine if any such influence was endothelium-dependent. Responses to changes in intravascular pressure of cannulated mesenteric small arteries were investigated under no-flow conditions. Both intact and endothelium-denuded arteries dilated passively when intravascular pressure was increased stepwise from 20 to 140 mmHg. When tone was induced by noradrenaline, pressure increase resulted only in dilatation, independent of endothelium. The sensitivity to noradrenaline was significantly increased in vessels without endothelium, indicating a relaxing influence of the endothelium. Rhythmic contractions in response to noradrenaline occurred in all intact arteries, but were absent when the endothelium was removed. The amplitude of the rhythmic contractions decreased significantly when transmural pressure was elevated. The frequency increased when pressure was elevated from 20 to 80 mmHg and then remained rather constant during further pressure increases. As shown previously in non-pressurized arteries, exogenous cyclic GMP induced oscillations in endothelium-denuded arteries. Pressure-related effects on vasomotion were not dependent on an intact endothelium. Ryanodine, ouabain or verapamil inhibited the rhythmic activity, confirming previous results in non-pressurized arteries. Thus, changes in transmural pressure can modulate vasomotion, but this effect does not appear to be mediated by the endothelium. Generation of vasomotion may depend on release of Ca2+ from intracellular stores, the activity of the Na+, K(+)-pump and transmembrane Ca2+ inflow in a pressurized artery as shown previously in these arteries under isometric conditions.

Animals↗
PubMed1994

Nonadrenergic noncholinergic vasodilation in bovine ciliary artery involves CGRP and neurogenic nitric oxide.

PURPOSE: Characterization of the nonadrenergic noncholinergic (NANC) vasodilator innervation in the anterior segment in the bovine eye. METHODS: The neurogenic tetrodotoxin-sensitive response to electrical field stimulation (EFS) of the intraocular segment of the bovine long posterior ciliary artery supplying the ciliary body was recorded using isolated ring segments of this artery mounted on an isometric myograph. After adrenergic and cholinergic receptor blockade (with phentolamine, propranolol, and atropine), the preconstricted vessels were subjected to EFS by passing constant current pulses (0.3 msec, 35 mA, 0.5 to 32 Hz) between two electrodes on either side of the vessel segments. RESULTS: EFS resulted in 60% relaxation of the active tone in 40 vessels. Treatment with capsaicin reduced the NANC response by 16 +/- 2% (P < 0.001) and inhibition of the NO synthase with 1 x 10(-4) M L-NOARG reduced the NANC response by 83 +/- 10% (P < 0.001). Desensitization of the vessels to substance P had no effect. The CGRP(8-37) fragment (1 x 10(-6) M) in the presence of 1 x 10(-4) M L-NOARG reversibly and competitively inhibited the NANC response. L-arginine partly antagonized the inhibition induced by L-NOARG. About 60% of the L-NOARG-sensitive component of the NANC response was inhibited by methylene blue. Combined incubation with capsaicin and L-NOARG nearly abolished the NANC response. The L-NOARG-sensitive/capsaicin-resistant relaxation was present in endothelium denuded vessels. The responses to EFS were blocked by TTX. CONCLUSIONS: The neurogenic NANC vasodilator response in the intraocular part of the bovine long posterior ciliary artery supplying the ciliary body is endothelium independent and consists of two components: a capsaicin-sensitive component mediated by CGRP released from sensory nerve endings and a larger L-NOARG sensitive component mediated by a direct "nitroxidergic" neurotransmission. The size of the nitroxidergic NANC response indicates that it has a physiological relevance in vivo.

Adrenergic Antagonists↗
PubMed1994

Simultaneous videoradiography and computerized pharyngeal manometry--videomanometry.

To obtain more information about muscle function in patients with dysphagia, simultaneous barium swallow and computerized pharyngeal manometry with solid-state pressure transducers was employed for the evaluation of the pharynx and the pharyngoesophageal segment (PES) in 30 consecutive patients. The manometry catheter was positioned under fluoroscopic control, providing localized measurements of the intraluminal pressures in the pharynx. Sixteen patients had a normal barium swallow. In 5 (31%) of these the manometry disclosed PES dysfunction, i.e. increased resting pressures between swallows in 3 patients (mean 120 +/- 13 mm Hg), and increased contraction pressures during peristalsis in 2 (mean 297 +/- 21 mm Hg). Barium swallow and manometry are complementary: the former reflecting transport through the pharynx and penetration to the airways, the latter the intraluminal pressures created by the pharyngeal wall. The combination of barium swallow and manometry gives information about pressure in relation to bolus transport, which may elucidate pharyngeal dysfunction.

Adult↗
PubMed1993

Trabecular patterns of the calcaneum as an index of osteoporosis. A comparison using gamma-absorptiometry.

Measurements of bone mineral content in the calcaneum were made by gamma-absorptiometry in 77 patients with ankle fractures treated by operation, and compared with the calcaneal osteoporosis index. The index was calculated from plain lateral radiographs of the calcaneum. The bone mineral measurements showed a wide range, but there was only a narrow range of the index with exclusively high values. There was a weak correlation between the calcaneal index and the bone mineral content in the injured ankles, but no or only a very poor correlation in the uninjured ankles. We also found no correlation between the decline in index and loss of mineral content in the injured ankles.

Absorptiometry, Photon↗
PubMed1993

Sympathetic activation after two weeks of nifedipine treatment in primary Raynaud's patients and controls.

The effect of a standardized cold pressor test on circulating noradrenaline and neuropeptide-Y-like immunoreactivity was investigated in 12 women with primary Raynaud's phenomenon and 12 healthy female controls before and after 2 weeks of treatment with the calcium antagonist, nifedipine. Measurement before treatment showed significant increase during the cold pressor test on circulating noradrenaline in both the primary Raynaud's phenomenon group and in the control group (from 0.29 +/- 0.15 ng/ml to 0.33 +/- 0.16 ng/ml, p < 0.05, and from 0.21 +/- 0.14 ng/ml to 0.29 +/- 0.16 ng/ml, p < 0.005, respectively). However, treatment with nifedipine resulted in significantly increased levels of circulating noradrenaline during the cold pressor test only in the control group (from 0.43 +/- 0.21 ng/ml to 0.50 +/- 0.20 ng/ml, p < 0.01). Plasma concentrations of neuropeptide-Y-like immunoreactivity were unchanged by the standardized cold pressor test, whether performed before or during nifedipine treatment in both groups. Nifedipine treatment per se significantly increased circulating noradrenaline in both the primary Raynaud's phenomenon patient group and in the control group (from 0.29 +/- 0.15 to 0.49 +/- 0.13 and 0.21 +/- 0.14 to 0.43 +/- 0.21 ng/ml, respectively, p < 0.001). Similarly, the circulating neuropeptide-Y-like immunoreactivity significantly increased in both the primary Raynaud's phenomenon group and in the control group (from 105 +/- 21 to 137 +/- 19 pmol/l and 107 +/- 17 to 147 +/- 13 pmol/l, respectively, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

Solar heat load on man. Review of different methods of estimation.

Different methods have been compared for the estimation of solar heat load on man. The comparison comprised several methods based on the calculation of absorbed solar radiation and one method for calculation of mean radiant temperature (Mrt). Regression analysis was carried out for predicted values and values calculated for a vertical cylinder, assumed as an analog model of a standing man. Regression of mean skin temperature, measured in 10 subjects exposed to solar radiation under a variety of climatic conditions, on predicted radiant heat load was also analysed. Mean skin temperature correlated best with Mrt, accounting for more than 50% of the variance. The results indicated that three methods provide a realistic estimation of the radiation heat load, whereas some methods show deviations of several hundred per cent.

Adult↗
PubMed1993

Pharyngeal constrictor paresis: an indicator of neurologic disease?

Pharyngeal constrictor paresis (PHCP) is sometimes found in videoradiography of the swallowing act in patients complaining of dysphagia. Ten patients with PHCP and 10 dysphagic, age- and sex-matched controls with normal videoradiography were neurologically evaluated and examined with magnetic resonance imaging (MRI) of the brain and brainstem in order to learn the pathogenetic process behind PHCP. The study revealed 8 PHCP patients and 1 dysphagic control with abnormal clinical neurological findings such as myopathy, cerebrovascular disease, or extrapyramidal disease. The neurological examination revealed considerable information of prognostic and therapeutic value in PHCP patients. The MRI was abnormal in 7 PHCP patients and 4 dysphagic controls. However, the findings in MRI were nonspecific but the examination was found to be valuable in selected cases. It is concluded that PHCP is an indicator of neurological disease and accordingly, such patients should be examined by a neurologist to establish the cause of the disease.

Adult↗
PubMed1993

Rhythmic contractions of isolated small arteries from rat: influence of the endothelium.

Small arteries of the mesenteric arcade from Wistar rats display rhythmic oscillations superimposed on the tonic contractile response when exposed to submaximal doses of noradrenaline. We have previously shown that mechanical removal of the endothelium abolishes these oscillations. In the present study different methods to eliminate or modify the influence of the endothelium were used in order to further characterize the mechanisms behind rhythmic contractions in these vessels. Endothelium was removed either mechanically or chemically by perfusing the vessels with 0.3% CHAPS. The absence of functional endothelium enhanced noradrenaline sensitivity and simultaneously abolished oscillations in tension and membrane potential, but did not affect resting membrane potential. The rhythmic activity was also reduced or abolished by exposure to haemoglobin, methylene blue, LY83583 or L-NNA. Indomethacin and propranolol were without effect. Sodium nitroprusside or the permeant analogue of cyclic GMP, 8-bromo cyclic GMP, restored rhythmic activity in precontracted endothelium-denuded vessels. The data suggest that release of nitric oxide from the endothelium, and subsequent generation of cyclic GMP in the smooth muscle, activates oscillations in membrane potential and tension; the oscillator itself appears to be located within the smooth muscle cells.

Aminoquinolines↗
PubMed1993

Rhythmic contractions of isolated small arteries from rat: role of calcium.

In order to investigate the mechanisms behind rhythmic contractions in small arteries of the mesenteric arcade from Wistar rats, the calcium dependency of the oscillations in response to noradrenaline activation was tested on isolated vessels. Application of 1 microM ryanodine or 30 microM TMB-8 (procedures known to inhibit Ca2+ release from intracellular stores) totally abolished the rhythmic activity, even though the antagonists had opposite effects on the amplitude of the contractile response to noradrenaline. Verapamil (1 microM) or felodipine (1 nM) (agents known to inhibit influx of extracellular Ca2+) also abolished the oscillations and reduced the maximal noradrenaline response by about 40%. Reducing the extracellular Ca2+ concentration to 0.1 mM reduced the amplitude of the noradrenaline response to a similar extent as 1 nM felodipine, but did not eliminate the oscillations. This may indicate that the effect of calcium entry blockers was to eliminate the voltage-dependency of Ca2+ inflow rather than just reducing the Ca2+ level. Manoeuvres that would increase the cytosolic Ca2+ concentration (exposure to caffeine or to the calcium agonist BAY-K 8644) increased the frequency of the oscillations. These observations indicate an important role, not only for voltage-operating channels, but also for intracellular calcium stores in the generation of rhythmic contractions in these small arteries. Oscillations appear to be generated by an interplay between membrane activation and intracellular calcium stores.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Free cytosolic Ca2+ measured with Ca(2+)-selective electrodes and fura 2 in rat mesenteric resistance arteries.

Free cytosolic Ca2+ was measured with sub-micrometer-tip, double-barrelled, Ca(2+)-selective electrodes and fura 2 in rat mesenteric resistance arteries. The purpose was to establish intracellular free Ca2+ concentration ([Ca2+]i) values in resting and stimulated vessels. Isolated vessels were mounted for isometric force measurements. Measured with electrodes, mean [Ca2+]i was 115 and 708 nM under resting and norepinephrine-activated conditions, respectively. Fura 2 was calibrated intracellularly including determination of the intracellular dissociation constant (Kd) of the fura 2:Ca2+ complex. The intracellular Kd was 342 nM. With this value of Kd, fura 2 measurements of mean [Ca2+]i were 129 and 537 nM under resting and norepinephrine-activated conditions, respectively. The values measured with the two techniques were thus in good accordance.

Animals↗
PubMed1992

Quantification of heat balance during work in three types of asbestos-protective clothing.

Three types of protective suits for asbestos removal work were tested in a climatic chamber at two ambient temperatures, 25 degrees and 36 degrees C. Four subjects performed 50 min of bicycle exercise at 90 W dressed in shorts, socks and sneakers (NoPS). The same test was carried out with three different types of asbestos-protective suits worn on top of NoPS. Suits were made of GoreTex (GT), polypropylene (PP) and Tyvek (TYV). At 25 degrees C, responses differed very little between suits and thermal strain was small. At 36 degrees C, strain was least with NoPS. TYV resulted in significantly higher physiological and thermal strain than did PP and GT. Evaporative heat loss was maintained at a similar level with less permeable ensembles, but at the expense of increased skin wetness and sweat rate. Measured values compared favourably with calculated values for skin wetness and sweat rate according to ISO 7933, when resultant, rather than standard, basic data for insulation and evaporative resistance of ensembles were used. Results indicate that differences between suits that may be of little importance at normal room temperature become significant at higher stress levels (increased activity and/or air temperature).

Asbestosis↗
PubMed1992

Inositol phosphates and phosphoinositides in rat liver nodules.

Total amounts and turnover rates of phosphoinositides and inositol phosphates in normal rat liver and hepatocyte nodules were investigated. Male Wistar rats were injected i.p. with [3H]inositol 18-20 h before killing. The amount of phosphatidylinositol in a homogenate preparation was roughly doubled in the nodules, though levels of polyphosphoinositides were approximately the same. Basal levels of inositol phosphates were the same in nodules and in normal liver. Turnover rates of inositol tris- and tetrakisphosphates were studied after stimulation of intact cells with vasopressin for different periods of time (0-5 min). The initial rate of formation of inositol trisphosphate after agonist exposure was fast in both nodular and normal cells. Nodular cells reached peak amount of inositol trisphosphate at 2.5-fold basal levels after 20 s, while normal cells peaked after 40 s at 4.5 times the basal amount. The level of inositol tetrakisphosphate was enhanced very quickly in normal cells, but in the nodular cells there was no increase of this inositol phosphate after vasopressin stimulation. To investigate the mechanism of this difference, the activities of inositol 1,4,5-trisphosphate kinase and of inositol 1,4,5-trisphosphate phosphatase were studied. Both activities were rapid and equal in nodules and normal liver. The amount of cell surface receptors for vasopressin was shown to be one-third in the nodules, as compared to normal cells. This quantitative decrease in receptor number was reflected in lower formation of inositol trisphosphate when stimulated with vasopressin, but could not explain the loss of inositol tetrakisphosphate response in nodules. The significance of the reported alterations in second messenger traffic for the growth regulation of nodular cells and for their progression to carcinoma is not yet known, but could add to the nodules being less dependent on growth regulating signals.

Animals↗
PubMed1992

Syncope--brain or heart? A case report.

A 44-year-old man suffered from recurrent episodes of unconsciousness, without any other concomitant manifestations. After routine workup, EEG and CT had proven nondiagnostic, prolonged Holter monitoring revealed a single episode of asystole, lasting 7.6 seconds. A pacemaker was inserted but did not abolish his episodic syncope. Subsequently, long-term EEG recording revealed epileptiform activity with independent foci in both temporal lobes. Antiepileptic treatment relieved the patient of his symptoms. This case illustrates the intimate relationship between the heart and the brain that sometimes lies behind syncope.

Adult↗
PubMed1992

Effect of chronic ethanol consumption upon cardiovascular reactivity, heart rate and blood pressure in spontaneously hypertensive and Wistar-Kyoto rats.

OBJECTIVE: Clarification of the effect of chronic ethanol consumption upon cardiovascular reactivity in rats. DESIGN: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) normotensive rats were randomly allocated in groups of 10 to ethanol in tap water [20% (v:v) after the first week or tap water for 7-12 weeks]. METHODS: Intra-arterial blood pressure and heart rate were measured at rest and in response to vibration and noise stress. Vascular reactivity was assessed in isolated paired perfused hindquarters and in mesenteric arterioles in a Mulvany-Halpern myograph. RESULTS: Resting intra-arterial blood pressure but not heart rate was lower in both ethanol-treated groups. The ethanol treatment increased the SHR heart rate response to sudden noise but the WKY response did not increase. Pressor responses to noise were initially greater in the ethanol-treated SHR. The ethanol had no effect upon isolated perfused hindquarter resistance at maximal dilation, dose-response curves in response to noradrenaline or vasopressin, or maximal contractile strength. Isolated mesenteric arterioles showed that ethanol had no effect upon responses to nerve stimulation or upon the 50% effective dose required for a response to noradrenaline or vasopressin. CONCLUSIONS: Ethanol treatment heightened the heart rate reactivity to stress without substantially affecting vascular neuro-effector characteristics in SHR. This is likely to be a central effect, caused by suppression of the central nervous inhibitory systems that influence the heart rate and baroreflex activity in a strain of rat already showing evidence of an impaired ability to modulate the heart rate and blood pressure in response to stress. The small reduction in resting blood pressure may be a consequence of the lower weight in the ethanol-treated rats, and/or may reflect a direct depressing action by the alcohol on vascular and cardiac muscle. These findings are discussed in the context of ethanol-induced hypertension in humans and possible genetic variations in central nervous, cardiac and vascular effects.

Alcoholism↗
PubMed1991

Incidence of work-related disorders and absenteeism as tools in the implementation of work environment improvements: the Sweden Post strategy.

In 1989, a comprehensive, five-year work environment project (Postal Work Environment [PWE] 2000) was launched by Sweden Post (SP). Its purpose was to identify the jobs and employees with the most exposed work environments and, in conjunction herewith, to initiate remedial programmes. Standardized interviews with a selection of employees and statistical and epidemiological evaluation of illness absenteeism and occupational injuries served as input data for devising different measures of work-related ill health (subjective complaints, symptoms, illness, illness absenteeism, and occupational injury). The results provided an incentive to regional action programmes, in which 'risk areas and risk occupations' were correlated with the load factors, primarily in ergonomic and work organization areas, cited in interview replies. In its regional efforts. PWE 2000 served as a stimulus/catalyst in the implementation of various regional action programmes.

Absenteeism↗