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Biomedical subjects

S Carlsson

Publications and source records attributed to S Carlsson.

At least 19 recordsLinked to original sources
PubMed1996

Differential responses in adrenal and renal nerves to CNS osmotic stimulation.

Hypertonic solutions act in the central nervous system (CNS) to increase mean arterial blood pressure (MAP) by activation of the sympathoadrenal axis. However, adrenal nerve activity (pre- and postganglionic nerve fibers) has not been determined during central osmotic stimulation. Therefore, these experiments evaluated adrenal (AdSNA) and renal (RSNA) sympathetic nerve activity, MAP, and heart rate (HR) following CNS administration of isotonic, hypertonic, and hypotonic sodium chloride solutions in chloralose-anesthetized rats. Injection of isotonic saline (5 microliters) did not alter MAP, HR, RSNA, or AdSNA. However, injection of hypertonic saline (5 microliters of 0.5 M) into the anteroventral portion of the third cerebral ventricle increased MAP (12 +/- 2 mmHg) and decreased HR (16 +/- 6 bpm). In addition, hypertonic saline significantly decreased RSNA (58 +/- 5% control), whereas AdSNA increased (158 +/- 10% control). Injection of hypotonic (5 microliters of 0.05 M) NaCl produced the opposite responses in RSNA (119 +/- 7% control) and AdSNA (86 +/- 5% control) and had no significant effect on MAP or HR. Furthermore, pre- and postganglionic adrenal nerve fibers responded similarly to changes in CNS osmolality. These results demonstrate that osmotic stimulation produces differential responses in RSNA and AdSNA, but not in pre- and postganglionic adrenal nerve fibers.

Adrenal Medulla↗
PubMed1996

The effects of hexamethonium on cerebral blood flow and cerebral function during relative cerebral ischaemia in rats.

Cerebral blood flow in either the cortex, thalamic region or the brain stem, as well as somatosensory evoked potentials were measured in a model of moderate cerebral ischaemia in three groups of anaesthetized spontaneously hypertensive rats. The rats were bled to reduce evoked potential amplitudes to approximately 50-60% of pre-haemorrhage control. The consequent blood pressure fall reduced blood flow to approximately 65, 80 and 85% of pre-haemorrhage control in the cortical, thalamic and brain stem regions, respectively, as measured with a laser Doppler flowmeter. Hexamethonium (10 mg kg-1 i.v.), an autonomic ganglion blocker, caused vasodilation and a slight (7-13 units of prebleeding control) increase in blood flow in all the three regions, and the somatosensory evoked potentials normalized. In addition, the latency of the first evoked potential component decreased toward prebleeding values. Heart rate decreased and a transient decrease was also observed in mean arterial pressure despite an attempt to keep it constant with a pressure regulating reservoir. It is possible that the slightly increased regional cerebral blood flow after hexamethonium injection can explain the improved cerebral function as indicated by the enhanced somatosensory evoked potentials. However, the results might also indicate an autonomic regulation of afferent sensory pathways.

Animals↗
PubMed1996

Carbohydrate-deficient transferrin and gamma-glutamyl transferase levels during disulfiram therapy.

Serum samples for quantification of carbohydrate-deficient transferrin (CDT) and gamma-glutamyl transferase (GGT) were collected from alcohol-dependent men and women upon admission to the hospital for detoxification, and repeatedly over a 3- to 5-week period of supervised disulfiram administration as outpatients. On admission, 10 of 12 patients showed CDT concentrations above the conventional cutoff limits, whereas 6 had elevated GGT values. Normalization usually occurred within 1 to 3 weeks of disulfiram treatment, after which CDT and GGT leveled out at a relatively stable individual baseline level. However, in those patients with the highest values on admission, the decline continued during the entire observation period. The time for normalization of GGT was typically longer than for CDT. In four male patients who had taken disulfiram regularly (400-800 mg every second or third day) for at least 3 months before entering the study, the CDT and GGT concentrations were stable over time and all fell within normal limits. The present results indicate that disulfiram treatment does not influence the serum level of CDT. It is also suggested that consecutive CDT and GGT measurements during outpatient treatment with disulfiram after detoxification can be used to identify the individual baseline (i.e., abstinence) values for CDT and GGT, and, furthermore, for monitoring treatment outcome.

Adult↗
PubMed1995

Somatostatin receptor scintigraphy in patients with carcinoid tumors: comparison between radioligand uptake and tumor markers.

We have performed 100 scintigraphic investigations using [111In-diethylenetriaminepentaacetic acid-D-Phe1]octreotide (111In-octreotide) single photon emission tomography (SPECT) in patients with carcinoid tumors. One or several lesions could be detected in 77 cases, and true negative results were obtained in 11 cases. There were false-negative results in 12 cases compared with results from conventional radiological methods. The ratio between the SPECT signals from the area with the highest uptake and normal lung was used as a tumor:background ratio. An attenuation correction was made in all investigations. We found that lesions in untreated patients had lower tumor:background ratios compared with those in patients treated with somatostatin analogues (medians, 10 and 40, respectively; P < 0.001) or IFN (median, 23; P = 0.03). In untreated patients, there was a correlation between the tumor:background ratio and the levels of urinary 5-hydroxyindoleacetic acid (U-5HIAA) and p-chromogranin A. The data obtained in the present investigation indicate that somatostatin receptor expression might be influenced by the treatment; i.e., a higher tumor:background ratio is found in patients treated with either somatostatin analogues or IFN. Furthermore, it was found that somatostatin receptor expression correlates with the levels of U-5HIAA and p-chromogranin A in untreated patients, and that 111In-octreotide SPECT scintigraphy is more likely positive in patients with elevated U-5HIAA values. This indicates that somatostatin receptor expression and elevated U-5HIAA are more likely present in patients with highly differentiated tumors and, thus, could be of prognostic value.

Adult↗
PubMed1995

Changes in serotonin metabolism during treatment with the aldehyde dehydrogenase inhibitors disulfiram and cyanamide.

The effect of the aldehyde dehydrogenase inhibitors disulfiram (Antabuse) and cyanamide (calcium carbimide, Dipsan) on the metabolism of serotonin measured as relative amounts of the metabolites 5-hydroxyindole-3-acetic acid and 5-hydroxytryptophol in urine were studied in alcoholic patients. Sixteen out of 23 patients receiving drug therapy showed elevated excretion of 5-hydroxytryptophol. However, there was a marked, 15-fold, variability in 5-hydroxytryptophol excretion rate between patients. A high degree of variability was also seen in another group of patients studied before and after introduction of drug therapy. When patients were followed during the dose interval, a time-dependent response after each single dose could be observed. The disulfiram response lasted over the course of several days whereas the response to cyanamide lasted for less than 12 hr. It is concluded that treatment with disulfiram and cyanamide affects serotonin metabolism leading to increased production of 5-hydroxytryptophol, but there is a marked inter-individual variability in degree of response.

Adult↗
PubMed1995

A glance at the history of nuclear medicine.

The development of nuclear medicine has resulted in several effective routine methods in diagnosis and therapy. There is an ongoing discussion about the future of activity based on the fast development of ultrasound, CT and MR. In such discussions, it is often forgotten that nuclear medicine is also a dynamic diagnostic tool under continuous progress. As seen from this historical review, nuclear medicine has grown from quite simple in vitro tests to very advanced methods to image organ function. This is the result of the development of radiopharmaceuticals and instrumentation. Today, development is moving towards what is called receptor scintigraphy, i.e., the use of radiopharmaceuticals which are very specific to certain diseases, for instance, tumours. Even at present there is no other method for early detection of bone metastases than bone scintigraphy. Also, there is no other method to determine the regional myocardial blood flow both at stress and at rest, than myocardial scintigraphy. Nuclear medicine will remain an important diagnostic tool as long as it employs people with engagement and interest. Such people will also guarantee that the hospital management will supply the activity with funds for the necessary investments.

History, 19th Century↗
PubMed1995

Closed-line integral optimization edge detection algorithm and its application in equilibrium radionuclide angiocardiography.

UNLABELLED: Automatic evaluation of left ventricular (LV) function using equilibrium radionuclide angiocardiography requires an edge detection algorithm to correct and reproducibly delineate the left ventricle. Available algorithms, usually based on differentiation of a radial profile, generally suffer from low precision due to low signal-to-noise ratios and overlapping structures, for example, the left atrium. METHODS: An edge detection algorithm was developed based on the assumption that the LV border can be defined as the maximum, normalized, closed-line integral of a closed curve in a vector field derived by image differentiation. It is further assumed that the closed curve can be described by a Fourier expansion with a limited number of harmonics. Regions of interest (ROIs) generated by this algorithm were compared with ROIs generated by an algorithm based on a combination of thresholding and second-order derivatives. RESULTS: This algorithm delineates the left ventricle and gives results more closely related to ROIs generated manually than the algorithm combining thresholding and the second-order derivative. Our algorithm can also handle the problem of overlapping structures, as demonstrated in phantom simulations. CONCLUSION: The concept of a maximum, normalized closed-line integral will improve the delineation of the LV in an equilibrium radionuclide angiocardiography study. The problem of overlapping structures is overcome by this algorithm because it takes into consideration global edge information.

Algorithms↗
PubMed1994

Characteristics of renal sympathetic nerve activity in experimental congestive heart failure in the rat.

Recently emerging evidence has indicated that efferent renal sympathetic nerve activity (RSNA) is increased in congestive heart failure (CHF). In the present study the cyclic activity of the renal nerve in the normal and CHF rat was studied. An ischaemic myocardial lesion resulting in CHF was induced by left coronary artery ligation. Sham-operated rats subjected to thoracotomy served as normal controls. Renal sympathetic nerve activity was recorded under chloralose anaesthesia. The neural cycle activity was significantly higher in CHF (47 +/- 3%) compared with sham-operated rats (34 +/- 3%, P < 0.005). Baroreceptor control of RSNA was significantly attenuated in CHF compared with normal control rats (P < 0.005). In response to noxious thermal stimulation by 48 degrees C water immersion of the tail tip, the increase of RSNA was significantly higher in CHF compared with sham-operated rats. A stepwise 15% blood volume expansion over 5 min which induced no alterations of blood pressure or heart rate (HR) resulted in a gradual decrease of RSNA in control rats by approximately 25% at the end of the volume expansion procedure. In CHF rats however, there was no significant change in RSNA during volume expansion. It is concluded that in CHF rats: (1) efferent RSNA is increased; (2) baroreceptor control of RSNA is decreased; (3) RSNA in response to cutaneous thermal noxious stimulation is exaggerated; and (4) RSNA inhibition by cardiopulmonary receptors is blunted.

Animals↗
PubMed1993

Maturation-related changes in tolerance development to hexobarbital after short term treatment with diazepam in the rat.

Male rats at six different ages received diazepam on a 4-day treatment schedule. Cross-tolerance to hexobarbital was tested several times during withdrawal period with an anaesthesia threshold technique. Pattern of cross-tolerance was different at different ages. Thus, age and maturation of the rat is a variable which must be considered in studies of tolerance to diazepam.

Aging↗
PubMed1993

Scintigraphic detection of gastro-pulmonary aspiration in patients with respiratory disorders.

The scintigraphic detection of small nocturnal aspirations of radio-labelled gastric contents is difficult in the presence of high remaining activity in the abdomen, causing a non-uniform background activity. This problem was examined in phantom experiments and a technique for interpolative background correction was further developed. The accuracy of this technique was found to be influenced by the distance between the lung and the abdominal source of activity, and the minimum detectable 'aspirated' activity was determined as 0.1 MBq at a distance of 15 cm and 1 MBq at 5 cm. The interpolative technique for background correction was evaluated on healthy volunteers and laryngectomized patients, examined 10 h after intragastric instillation of 200 MBq of 99Tcm-pertechnetate. After background subtraction, their calculated pulmonary mean net count value was comparable to that registered before the radioactive tracer was administered. No localized accumulation of activity was found in any of these controls. The technique was then applied clinically to 55 patients with chronic respiratory disorders and symptoms of gastroesophageal reflux. Aspiration was detected in 11 patients (20%). Five aspirators had asthma, two a chronic cough of unknown origin, two recurrent pulmonary infections, and one chronic bronchitis and chronic laryngitis respectively. Aspiration was detected among patients with and without demonstrated pathological gastroesophageal reflux.

Adult↗
PubMed1993

Tolerance to hexobarbital induced by short-term treatments with diazepam and tested with an EEG-threshold test in male rats.

Male Mol: SPRD rats were treated with 5 or 20 mg/kg of diazepam for 4 days. The treatment was repeated at two different ages. Diazepam was either dissolved in Intralipid (KABI, Sweden) or dispersed in gummi arabicum. Tolerance induced by the treatment was tested with an EEG-threshold technique where hexobarbital was infused intravenously on day 1, 4, 7 and 14 of the abstinence. The threshold was the dose of hexobarbital needed to induce a burst suppression of 1 sec. or more (silent second). After the first diazepam treatment significant increase in the hexobarbital threshold doses were recorded in all but one of the diazepam treated groups. The pattern varied depending on dose, age and solvent. After the second treatment tolerance was seen only when diazepam had been dissolved in Intralipid. Short term treatment with diazepam can induce cross-tolerance to hexobarbital which probably is due to an increased excitation (physical dependence) in abstinence after treatment with diazepam.

Animals↗
PubMed1993

Evidence for an adrenergic innervation of the adrenal cortical blood vessels in rats.

The aim of this study was to investigate the blood flow in the adrenal cortex of the rat. Relative changes in the adrenal cortical blood flow were continuously measured by Laser Doppler flowmetry in 33 chloralose-anaesthetized artificially ventilated rats during electrical stimulation (1 ms, 5 V) of the left great splanchnic nerve (LGSN), which conveys both pre- and post-ganglionic nerve fibres to the adrenal gland. Laser Doppler flux (LDF) was decreased and regional resistance (RR) was increased by augmenting nerve stimulation at increasingly higher frequencies (2, 4, 8, 20 and 40 Hz). The decrease in LDF, when compared to pre-drug stimulations at 4 Hz was partially or totally inhibited by the adrenergic blocking agents trimethaphan (TRIM), guanethidine (GUA) and alpha 1-blockade with prazosin (PRAZ). Furthermore, both the decrease in LDF and the increase in RR were either completely or partially blocked by stimulation at 40 Hz after TRIM-treatment and GUA-treatment. It is concluded that the adrenal cortex in the rat is innervated by post-ganglionic adrenergic nerve fibres, which are involved in the regulation of blood flow in the adrenal cortex.

Adrenal Cortex↗
PubMed1992

Reflex changes in post- and preganglionic sympathetic adrenal nerve activity and postganglionic sympathetic renal nerve activity upon arterial baroreceptor activation and during severe haemorrhage in the rat.

The aim of the study was to compare pre- (pre-aSNA) and postganglionic adrenal sympathetic nerve activity (post-aSNA) and postganglionic renal sympathetic nerve activity (rSNA) in rats during arterial baroreceptor activation and haemorrhage. Adrenal multifibre nerve activity was recorded in chloralose-anaesthetized Wistar rats. To test for pre-aSNA or post-aSNA in adrenal nerves, a ganglionic blocker, trimethaphan (10 mg kg-1), was administered i.v. If the nerve activity in the adrenal nerve decreased or increased the nerve was considered to contain predominantly post- or preganglionic fibres, respectively. In contrast, the renal nerves exhibit an almost pure postganglionic activity. Baroreceptor activity was tested by activation of baroreceptors, with an alpha-receptor agonist, phenylephrine, which was slowly infused (0.5-2 micrograms kg-1 min-1), and to deactivate the baroreceptors the rats were bled down to 50 mmHg for 8 min. The experiments showed that all tested nerve types were baroreceptor dependent. There were no significant differences between the slopes relating nerve activity inhibition to increase in blood pressure (infusion of phenylephrine). During maximal inhibition there was a difference between the rSNA and pre-aSNA, 87 +/- 4%, n = 6, and 68 +/- 6%, n = 10 (P less than 0.01) of the control value, respectively. The maximal inhibition of post-aSNA was 80 +/- 3%, n = 7, of the control value. During haemorrhage there was a difference between the nerve populations. Pre-aSNA responded with a marked increase within 1.5 min (159 +/- 29% of control, n = 7) and was then maintained at that level until retransfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1992

Differential responses in post- and pre-ganglionic adrenal sympathetic nerve activity and renal sympathetic nerve activity after injection of 2-deoxy-D-glucose and insulin in rats.

The aim of the study was to compare pre-ganglionic adrenal nerve activity (pre-aSNA) to post-ganglionic adrenal nerve activity (post-aSNA) in rats after administration of 2-deoxy-D-glucose (2-DG, 500 mg kg-1, i.v.), which mimicks a central hypoglycaemia or to the response in pre-aSNA and post-aSNA to hypoglycaemia after injection of insulin (5U). Renal postganglionic sympathetic nerve recordings (rSNA) in a separate group was used as a reference. Adrenal or renal multifibre nerve activity was recorded in chloralose-anaesthetized Wistar-rats. Trimethaphan, a short-lasting ganglionic blocker, was administered i.v. (10 mg kg-1) in order to test for pre- or post-aSNA in the adrenal nerves. The adrenal nerves was considered to contain predominantly post or preganglionic fibres, respectively if the nerve activity in the adrenal nerve decreased (post-aSNA) or increased (pre-aSNA). In contrast, all renal nerves showed almost a pure postganglionic activity. Post-aSNA responded with a tendency to increase after the 2-DG injection. The highest value (percentage change from control) 5 min after injection was 12 +/- 9%. The pre-aSNA increased with values of 99 +/- 52% at 3 min and 86 +/- 31% at 5 min (percentage change from control). The activity in the rSNA was only slightly decreased after the injection of 2-DG when compared to pre-drug control activity. There was a significant difference between the pre-aSNA vs. post-aSNA at 1 min (P less than 0.05), 3 min (P less than 0.01) and 5 min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1992

Quantitative assessment of esophageal transport with normalized condensed images.

Scintigraphy is one of several diagnostic procedures used to investigate dysphagia. Several different methods to present the bolus transport have been presented. The normalized condensed image enables quantitative assessments of patterns of bolus transport and a descriptive nomenclature of these patterns: the "L-h-S-E-m-system", based on results of 25 subjects without dysphagia, is suggested. Aberrant patterns were found in 40% of the swallows.

Adult↗
PubMed1992

Effects of clonidine on renal sympathetic nerve activity, natriuresis and diuresis in chronic congestive heart failure rats.

The differential effects of the alpha-2 adrenergic agonist, clonidine, on blood pressure, renal sympathetic nerve activity (RSNA) and renal responses were investigated in conscious as well as anesthetized congestive heart failure (CHF) rats and normal control animals. After the stepwise increments of i.v. clonidine infusion (5, 15 and 30 micrograms/hr for 1 hr), mean arterial pressure gradually decreased in CHF, but increased significantly in the control animals at the higher doses. Urinary volume, sodium and potassium excretions were significantly higher in the normal control animals after the clonidine 30-micrograms/hr infusion compared with the CHF rats. There were almost immediate decreases in RSNA in both the CHF and control groups. Although the control animals reduced RSNA to about 5%, the CHF rats retained 36.5% of their respective control values after clonidine administration. Base-line plasma immunoreactive atrial natriuretic peptide were increased 7-fold in the CHF rats compared to controls. After clonidine, immunoreactive atrial natriuretic peptide increased more than 3-fold in the normal rats, whereas no changes were observed in the CHF group. Our data show that clonidine decreases RSNA in CHF and that the natriuretic and that diuretic effects of an alpha-2 receptor agonist are blunted in experimental CHF. Furthermore, the different mean arterial pressure response in the CHF and control groups at higher doses of clonidine may suggest down-regulation of the vascular alpha-2 adrenergic receptor in CHF.

Animals↗