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Biomedical subjects

A Svensson

Publications and source records attributed to A Svensson.

At least 91 records · Page 5Linked to original sources
PubMed1996

Long-term effects of losartan on blood pressure and left ventricular structure in essential hypertension.

In a 12-week, randomized, double-blind study, 24 patients with essential hypertension were given the angiotensin II antagonist losartan, or the beta-adrenoceptor blocker atenolol. Both drugs reduced blood pressure (BP) well, but losartan tended to reduce left ventricular mass (LVM) in contrast to atenolol. Following the double-blind phase 19 patients entered an open treatment period with losartan and additional treatment if BP was uncontrolled. LV structures were measured by echocardiography. The mean follow-up period was 29 +/- 2.6 (range 26-32) months. BP was reduced from 155.6 +/- 15.6/103.4 +/- 5.2 mm Hg to 131.3 +/- 10.5/82.7 +/- 3.3 mm Hg (P < 0.001). LV internal diameter was reduced (50.7 +/- 4.5 to 49.1 +/- 4.0 mm; P = 0.006), while there was an increase in interventricular septal thickness (10.2 +/- 1.1 to 11.2 +/- 1.3 mm; P = 0.001) and posterior wall thickness (10.0 +/- 0.9 to 10.6 +/- 1.1 mm; P = 0.023). Calculated LVM was not significantly altered during the follow-up period. In conclusion, losartan is effective in reducing BP during long-term treatment. No significant effect on LVM was observed, but there was an increase in LV wall thickness.

Adult↗
PubMed1995

Allelotyping of follicular thyroid tumors.

To elucidate further the genetic mechanisms for follicular thyroid tumor development and progression, we allelotyped follicular thyroid tumors and other thyroid lesions from 92 patients. In general, a low frequency of loss of heterozygosity (LOH) was found, the highest being for chromosomes 3q, 10q, 11p, 11q, 13q, and 22q (10%-15%). However, detailed study of LOH of these chromosome arms with regard to the different histopathological diagnoses indicates that a locus on chromosome 10q may be involved in follicular thyroid tumor progression. In addition, the majority of Hürthle cell adenomas showed LOH on either chromosome 3q or 18q, in contrast to the other tumor types. This discrepancy in genetic alterations may contribute to the divergent clinical features occurring in these tumors.

Adenocarcinoma, Follicular↗
PubMed1995

Crucial role of the accumbens nucleus in the neurotransmitter interactions regulating motor control in mice.

Previous work, based on systemic drug administration, has shown that neurotransmitter interactions between dopaminergic, adrenergic, glutamatergic and cholinergic systems are involved in locomotor control in mice. In an attempt to identify the target sites in the brain of these interactions, we have started a series of experiments, where the drugs are administered intracerebrally in mice. The locomotor threshold doses of the competitive NMDA antagonist AP-5 and the noncompetitive NMDA antagonist MK-801 were investigated by means of local application in the accumbens nucleus of monoamine-depleted and monoaminergically intact mice, respectively. The threshold dose of AP-5 was lower in depleted than in intact animals, whereas the threshold dose of MK-801 was lower in monoaminergically intact than monoamine-depleted mice. The locomotor effects of AP-5 and the AMPA-kainate receptor antagonist CNQX were registered in monamine-depleted mice after local application in the accumbens or entopeduncular nucleus (= medial pallidum). Both AP-5 and CNQX stimulated locomotor activity in the accumbens, but had no effects in the entopeduncular nucleus. We have previously shown synergistic interactions with regard to locomotor stimulation in monoamine-depleted mice, between an NMDA antagonist and an alpha 2-adrenoceptor agonist or a dopamine D1 agonist (all drugs given systemically). In the present study the alpha 2-adrenoceptor agonist alpha-methylnoradrenaline was applied intracerebrally in combination with a subthreshold dose of MK-801 given intraperitoneally: Locomotor stimulation was produced after alpha-methyl-noradrenaline injection into the accumbens nucleus, but not after injection into the dorsal striatum, prefrontal cortex or thalamus. Likewise, local application of the D1 agonist SKF 38393, in combination with a subthreshold dose of MK-801 given intraperitoneally, point to an important role of the accumbens nucleus in motor control. Previous experiments based on systemic drug administration have also shown a synergistic interaction between a muscarine antagonist and an alpha 2-adrenoceptor agonist in monoamine-depleted mice. Local application of the muscarine antagonist methscopolamine, in combination with the alpha 2-adrenoceptor agonist clonidine given intraperitoneally, showed that the striatum, in this case both the ventral and dorsal parts of the striatum, is an important target for the muscarine antagonist. Unilateral injection of AP-5 into the accumbens nucleus of mice induces rotational behaviour: Previous findings have shown that the rotation is ipsilateral in monoaminergically intact animals, whereas monoamine-depleted animals rotate contralaterally. In addition, these findings have shown that dopamine D2 receptor stimulation seems to determine whether AP-5 will induce ipsilateral or contralateral rotation. In the present study we report further evidence for a crucial role of the D2 receptor in this respect. Finally, the rotational effects of AP-5 injected into the dorsal striatum or hippocampus were investigated: As after AP-5 application into the accumbens nucleus, monoaminergically intact mice rotated ipsilaterally, whereas monoamine-depleted animals rotated contralaterally, following AP-5 application in the dorsal striatum or the hippocampus. The present data show that the accumbens nucleus has an important role in motor control. Both glutamatergic, muscarine cholinergic, dopaminergic and alpha-adrenergic systems are involved in the control of motor functions in the accumbens nucleus.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1995

The muscarine antagonist methscopolamine and the NMDA antagonist AP-5 injected unilaterally into the nucleus accumbens cause mice to rotate in opposite directions.

Previously, we have reported that the NMDA antagonist AP-5, injected unilaterally into the nucleus accumbens of mice, induces ipsilateral rotation in monoaminergically intact mice, but contralateral rotation in monoamine-depleted animals. In this paper we report that the muscarine antagonist methscopolamine, injected unilaterally into the nucleus accumbens, induced predominantly contralateral rotation in monoaminergically intact mice. In monoamine-depleted animals intra-accumbens methscopolamine induced only a weak stimulation of rotational behaviour (not significant), but the direction of the rotation was exclusively contralateral, and the animals showed contralateral body deviation. Moreover, when these animals received additional treatment with the alpha-adrenergic agonist clonidine, which potentiates the motor effects of cholinergic antagonists in monoamine-depleted mice (Carlsson et al., 1991), a clear-cut contralateral rotation was induced. The observed behavioural effects are discussed in relation to the positive and negative feedback circuits, which link the nucleus accumbens with the cerebral cortex and thalamus. In previous papers, we have suggested that the ipsilateral rotation induced by AP-5 is mediated primarily by the positive feedback circuit, whereas the AP-5-induced contralateral rotation is due to interference with primarily the negative feedback circuit. Applying this reasoning to the rotational effects of methscopolamine, it seems that methscopolamine interferes primarily with the negative feedback circuit.

2-Amino-5-phosphonovalerate↗
PubMed1995

On the simultaneous distribution of size and costs of an epidemic in a closed multigroup population.

A multitype stochastic epidemic model in which the infectivities and susceptibilities differ between subgroups is considered. To each infected are associated random effects of the infection, such as the development of a subsequent disease and the length of the infectivity period. Sums of the corresponding random variables are called costs of the epidemic. The asymptotic simultaneous distribution of the size and costs of large epidemics is derived.

Costs and Cost Analysis↗
PubMed1995

Vertical load distribution on a three-unit prosthesis supported by a natural tooth and a single Brånemark implant. An in vivo study.

In vivo bite forces, implant axial forces and bending moments were measured on 5 patients with fixed posterior prostheses supported by a natural tooth and a single Brånemark implant. The results demonstrate that the vertical loads applied to the prostheses are shared between the tooth and the implant. The maximum bending moment transferred to the implant (10-15 N.cm) was well below the acceptable load limits for the mechanical components (50-60 N.cm), even at bite forces exceeding 100 N. The main reason for this load sharing seems to be the inherent bending flexibility of the implant screw joint, which matches the axial flexibility of the periodontal ligament of the tooth.

Aged↗
PubMed1995

Localization of major allergens in the dust mite Lepidoglyphus destructor with confocal laser scanning microscopy.

The dust mite Lepidoglyphus destructor is the dominating source of allergens giving rise to asthma and rhinitis among farmers. In a previous study of the localization of allergens in L. destructor we demonstrated that the 39 kDa allergen is associated with digestion. Here we describe the localization of the principal 15 kDa allergen and the high molecular weight allergen complex (79 and 93 kDa) in L. destructor with confocal laser scanning microscopy (CLSM). Cryostat-cut sections of mite bodies and faecal pellets were probed with mouse monoclonal antibodies (MoAbs) raised against the allergens. The 15 kDa allergen disclosed labelling of the mite body and most of the faecal pellets but left the exoskeleton unlabelled. The binding was widespread, and most intense in the mouth region. However, some staining was also observed around the gastrointestinal tract. In contrast, the 79 and 93 kDa allergen complex stained the exoskeleton and the front part of the mite. Interestingly, we detected no labelling of the faecal pellets with the MoAb against the 79/93 kDa allergen. The study indicates that the 15 kDa allergen is associated with the digestive tract whereas the function of the 79 and 93 kDa allergen complex remains to be elucidated.

Allergens↗
PubMed1995

Increase of monocytes predicts mobilization of peripheral stem and progenitor cells after chemotherapy followed by G-CSF administration.

Mobilization of primitive haematopoietic cells to the peripheral blood was studied in 25 patients with haematological malignancies. The optimal level of peripheral stem cells (PSC), defined by their surface expression of CD34, was significantly higher after mobilization with G-CSF, either following chemotherapy or alone (median: 123 x 10(6)/l and 143 x 10(6)/l of CD34+ cells respectively) than without administration of G-CSF subsequent to chemotherapy (median: 27 x 10(6)/l of CD34+ cells). An individual variation in when optimal mobilization of CD34+ cells and myeloid progenitors occurs after chemotherapy and G-CSF administration was noted (median: day 12, range 7-24 days), which makes it difficult to predict when PSC collections in a given patient should be performed. In this study, chemotherapy followed by G-CSF administration resulted in a short lasting (2-3 days) peak appearance of CD34+ cells that could predicted by a 2-fold increase in absolute numbers of monocytes, as compared to the previous day. After the peak level of CD34+ cells in the blood was reached, no further increase in monocytes was seen. The identification of an increase in monocytes, to be used as a predictive variable for when optimal mobilization of PSC will occur in a given patient, may be particularly useful in the individual timing of PSC collections from non-hospitalized patients.

Adolescent↗
PubMed1995

Mutations of codon 918 in the RET proto-oncogene correlate to poor prognosis in sporadic medullary thyroid carcinomas.

The hereditary multiple endocrine neoplasia syndromes types 2A and B (MEN 2A and B) were recently linked to germline mutations in the RET proto-oncogene, altering one of five cysteine residues in exon 10 or 11 (MEN 2A), or substituting a methionine for a threonine at codon 918 in exon 16 (MEN 2B). The latter mutation also occurs somatically in some sporadic medullary thyroid carcinomas (MTC), and has in a previous study been correlated with a less favorable clinical outcome. In the present study, 46 MTCs were selected for investigation of the codon 918 mutation. The mutation was found in 29 tumors (63%), and was significantly correlated with a poor outcome, with regard to distant metastasis or tumor recurrence (p < 10(-4)). Two tumors showed multifocal growth and C-cell hyperplasia, and these patients were therefore also investigated for germline mutations in exons 10, 11 and 16. The codon 918 mutation was found only in the tumors, thus of somatic origin. The RET codon 918 mutation may have prognostic impact, and therefore preoperative assessment may influence decision-making in the treatment of patients suffering from MTC.

Base Sequence↗
PubMed1995

Metabolic carotenemia and carotenoderma in a child.

We describe a 3-year-old girl with long-standing yellow discoloration of her skin and a 3-fold increase in the plasma carotenoid concentration compared to normal, but no history of excessive carotene intake or familial carotenemia. When put on a carotene-deficient diet for 8 months she still had some remaining yellow discoloration in the nasolabial folds and on the palms and soles. The results of an oral loading with beta-carotene (1 mg/kg) provide indirect evidence that the girl's carotenemia is due to a probably genetic defect in the metabolism of carotenoids.

Carotenoids↗
PubMed1995

Evaluation of in vitro properties of films of saliva substitutes in contact with different surfaces. A comparative study with instruments for measurements of friction and rheologic properties.

An instrument based on friction measurement has been developed to evaluate oral mucosal dryness objectively. The purpose of this study was to compare the friction instrument with instruments measuring in vitro rheologic properties. Measurements were performed against steel and irreversible hydrocolloid after application of different concentrations of aqueous solutions of carboxymethylcellulose and chitosan lactate. The results of the measurements were logical, with inversely proportional values for the friction instrument as compared with values obtained using the instrument measuring rheologic properties; that is, increased viscosity led to decreased friction values.

Alginates↗
PubMed1995

X-ray evidence that in contracting live frog muscles there exist two distinct populations of myosin heads.

Using synchrotron radiation and whole muscles, 2 ms time-resolved x-ray diffraction patterns were recorded at 8 degrees C. The results show that in both isotonic and isometric contractions, as well as in length changes imposed at maximum tension [Po], the meridional third myosin layer line consists of two distinct reflections with different intensities and spacings that measure approximately 14,623 and 14,412 nm at Po. Although the intensity behavior of the two reflections is strikingly different during quick releases, it is very similar during stretches. Study of the time courses indicates that myosin heads diffracting at Po with the approximately 14.623 nm periodicity are actively involved in tension production. Those diffracting at Po with the periodicity of approximately 14.412 nm appear not be associated with tension production during isometric contraction and releases, but the results suggest that they are recruited during stretches and here contribute to tension production. Our most important conclusion is that under all conditions of contraction we have investigated there exist two populations of myosin heads, each with a well defined axial disposition and configuration.

Animals↗
PubMed1994

Time-resolved X-ray diffraction studies of myosin head movements in live frog sartorius muscle during isometric and isotonic contractions.

Using the facilities at the Daresbury Synchrotron Radiation Source, meridional diffraction patterns of muscles at ca 8 degrees C were recorded with a time resolution of 2 or 4 ms. In isometric contractions tetanic peak tension (P0) is reached in ca 400 ms. Under such conditions, following stimulation from rest, the timing of changes in the major reflections (the 38.2 nm troponin reflection, and the 21.5 and 14.34/14.58 nm myosin reflections) can be explained in terms of four types of time courses: K1, K2, K3 and K4. The onset of K1 occurs immediately after stimulation, but that of K2, K3 and K4 is delayed by a latent period of ca 16 ms. Relative to the end of their own latent periods the half-times for K1, K2, K3 and K4 are 14-16, 16, 32 and 52 ms, respectively. In half-times, K1, K2, K3 lead tension rise by 52, 36 and 20 ms, respectively. K4 parallels the time course of tension rise. From an analysis of the data we conclude that K1 reflects thin filament activation which involves the troponin system; K2 arises from an order-disorder transition during which the register between the filaments is lost; K3 is due to the formation of an acto-myosin complex which (at P0) causes 70% or more of the heads to diffract with actin-based periodicities; and K4 is caused by a change in the axial orientation of the myosin heads (relative to thin filament axis) which is estimated to be from 65-70 degrees at rest to ca 90 degrees at P0. Isotonic contraction experiments showed that during shortening under a load of ca 0.27 P0, at least 85% of the heads (relative to those forming an acto-myosin complex at P0) diffract with actin-based periodicities, whilst their axial orientation does not change from that at rest. During shortening under a negligible load, at most 5-10% of the heads (relative to those forming an acto-myosin complex at P0) diffract with actin-based periodicities, and their axial orientation also remains the same as that at rest. This suggests that in isometric contractions the change in axial orientation is not the cause of active tension production, but rather the result of it. Analysis of the data reveals that independent of load, the extent of asynchronous axial motions executed by most of the cycling heads is no more than 0.5-0.65 nm greater than at rest.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

On the roles of dopamine D-1 vs. D-2 receptors for the hyperactivity response elicited by MK-801.

The present study was aimed at clarifying to what extent the hypermotility induced by the uncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801 depends on dopamine (DA) D-1 compared to D-2 receptor tone. The D-1 receptor antagonist SCH 23390 was found to reduce locomotion to a greater extent in MK-801-treated than in vehicle-treated mice, whereas the reverse appeared to be the case for the DA D-2 receptor antagonist raclopride. In other words, MK-801-induced hyperactivity was more readily antagonized by SCH 23390 than by raclopride and, thus, DA D-1 receptors seem to be more important than D-2 receptors for MK-801-induced hyperactivity. These results are in line with our previous observation that MK-801 generally interacts synergistically with a DA D-1 but not with a D-2 receptor agonist in monoamine-depleted mice. In view of the possible role of deficient glutamatergic neurotransmission in schizophrenia, our findings underline the importance of investigating the efficacy of selective DA D-1 antagonists in this disorder.

Animals↗
PubMed1994

Glutamatergic neurons projecting to the nucleus accumbens can affect motor functions in opposite directions depending on the dopaminergic tone.

1. Intracerebral cannulas were implanted stereotactically into the nucleus accumbens, dorsal striatum or nucleus entopeduncularis of male NMRI mice. 2. Monoamine-depleted mice were injected intracerebrally with the competitive NMDA receptor antagonist AP-5, the non-competitive NMDA antagonist MK-801 or the AMPA-kainate receptor antagonist CNQX. A marked locomotor stimulation was produced when AP-5 was injected into the nucleus accumbens, but not when injected into the dorsal striatum. Likewise, CNQX stimulated locomotor activity when injected into the nucleus accumbens. Neither AP-5 nor CNQX produced behavioral stimulation following injection into the nucleus entopeduncularis. 3. The tone in the monoaminergic systems influences the potency of competitive and non-competitive NMDA antagonists differently with regard to stimulation of locomotor activity. In the case of the competitive NMDA antagonist AP-5 the potency was higher in monoamine-depleted than in monoaminergically intact mice. In contrast, the potency of the non-competitive NMDA antagonist MK-801 was higher in monoaminergically intact than in monoamine-depleted animals. 4. A unilateral injection of AP-5 into the nucleus accumbens caused the animals to rotate: The rotation was predominantly ipsilateral in monoaminergically intact animals, whereas monoamine-depleted mice rotated exclusively contralaterally. When AP-5 was given to monoamine-depleted mice treated with the D-2 agonist quinpirole the animals rotated ipsilaterally, whereas monoamine-depleted mice treated with the D-1 agonist SKF 38393 still rotated contralaterally after AP-5 treatment. These data show that glutamatergic neurons projecting to the nucleus accumbens can affect behavior in different directions depending on the degree of dopamine D-2 receptor stimulation.

2-Amino-5-phosphonovalerate↗
PubMed1994

Predictors of blood pressure and left ventricular mass in the young: the Hypertension in Pregnancy Offspring Study.

The present study evaluates potential predictors for the future blood pressure and left ventricular mass in children. Fifty-two children were studied at mean age 12.6 +/- 1.5 years and reexamined after 5.6 years. Thirty-six children were born to mothers who had hypertension during pregnancy and 16 children were born after normotensive pregnancies by mothers who remained normotensive at follow-up. Blood pressure was measured at rest and during physical exercise. Left ventricular mass was calculated from M-mode echocardiography, and erythrocyte sodium and potassium concentrations were determined. A stepwise multiple linear regression analysis was used to predict subsequent blood pressure and left ventricular mass. Final systolic blood pressure was best explained by initial systolic blood pressure, erythrocyte potassium concentration, gender, and erythrocyte sodium concentration. Final diastolic blood pressure was best explained by erythrocyte potassium concentration. Gender and initial left ventricular mass were predictors of left ventricular mass at follow-up. This prospective study corroborates previous findings that blood pressure measured in children predicts their future blood pressure. Furthermore, an independent inverse relationship between childhood erythrocyte potassium concentration and adolescent blood pressure is demonstrated. Male gender and an early increased left ventricular mass are independent predictors of an increased left ventricular mass in adolescents.

Blood Pressure↗