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Biomedical subjects

H Larsson

Publications and source records attributed to H Larsson.

177 records · Page 10Linked to original sources
PubMed1975

Effects of barbiturates on ultrastructure and polymerization of microtubules in vitro.

Barbiturates were examined for in vitro effects on ultrastructure of the frog sciatic system and polymerization of microtubules (MT) in a brain supernatant. Exposure for 5-17 h to 2.0 mM barbiturates caused a considerable loss of MT in ganglionic cell bodies and sciatic axons. This was mostly followed by a proliferation of 10 nm filaments. Under similar conditions treatment with 1 mM NaCN or 0.1 mM 2,4-DNP did not change the number or ultrastructure of MT and filaments. Eight barbiturates, varying in binding ratios to serum albumin and partition coefficients, were tested for effects on polymerization of MT using viscometry. Inhibitory effects were found which correlated with their reported ability to bind to albumin and brain fractions. Dimethylsulphoxide and ethanol were used as solvents for some of the barbiturates. These solvents at 1% had stabilizing effects on MT. The present results are discussed in relation to previous findings of inhibition of rapid axonal transport in vitro in the frog sciatic system by barbiturates.

Animals↗
PubMed1975

Plasma level and broncholytic effect of choline theophyllinate after a single dose of a press-coated tablet formulation.

The broncholytic effect and plasma concentrations of theophylline in 10 asthmatic patients were studied for 8 hours after a single dose of 600 mg choline theophyllinate in press-coated 200 mg tablets. Therapeutic concentrations of theophylline were rapidly achieved and the plasma peak averaged 10.4 mug/ml after 2 hours. The broncholytic effect was closely related to the plasma level of theophylline. The largest change was in FEV1, which was significantly increased 1 to 6 hours after the dose. No patient complained of adverse effects. A theophylline concentration of 7 mug/ml plasma was adequate for a broncholytic effect, but a higher level was required for a maximal response. The results provide a basis for further studies to establish a dosage schedule suitable for prolonged therapy.

Adult↗
PubMed1975

Plasma theophylline level and ventilatory function in chronic obstructive pulmonary disease during prolonged oral treatment with choline theophyllinate.

Plasma levels of theophylline and broncholytic activity have been studied in 12 patients with chronic obstructive pulmonary disease during prolonged oral treatment with choline theophyllinate, administered as a press-coated tablet (BrondaxinR). The plasma levels determined immediately before and 80 minutes after each dose showed very good agreement with those calculated on the basis of data from a previous single dose study. The plasma concentration and improvement in ventilatory function were closely correlated throughout the 48 hours of the study. A tendency towards further reduction of bronchial obstruction was observed during the second day, despite essentially unchanged plasma levels of theophylline. The results provide a rational basis for determination of an optimal dose schedule for oral treatment with choline theophyllinate to reduce the symptoms of obstructive bronchial disease.

Adult↗
PubMed1973

Hypertension, asymmetric renal parenchymal defect, sterile urine, and high E. coli antibody titre.

During an 11-year period four children were seen with asymmetric renal parenchymal reduction, arterial hypertension, and sterile urine. The history and radio-logical or histological findings, or both, were consistent with "abacterial pyelonephritis" induced by bacterial infection in early childhood. All four had raised antibody titres to Escherichia coli. Three possibilities may explain the high antibody titres and insidious course of the renal damage-the presence of bacterial variants or amorphous bacterial antigen in the kidneys or the fact that because of cross-reactivity between certain E. coli O antigens and renal tissue the "E. coli antibodies" were, in fact, autoantibodies.

Adolescent↗
PubMedDate not supplied

In vitro and in vivo evaluation of controlled-release and enteric-coated formulations of sodium salicylate.

The bioavailability and pharmacokinetics of salicylic acid (SA) were studied after single and multiple doses of a new slow-release formulation, based on porous membrane diffusion of sodium salicylate (NaSA). A solution of NaSA and an enteric-coated tablet of NaSA were used for comparison. Dissolution rate studies were carried out at various pH values, and both solid formulations showed pH-dependent release rates. The enteric-coated tablet released its content rapidly at intestinal pH but slowly and irregularly at gastric pH. The dissolution from the controlled-release formulation at intestinal pH was completed after 6h and the drug was delivered at a constant rate. At gastric pH the release rate was lower but complete release was obtained within 24h. The novel formulation appeared to offer complete bioavailability of SA and an even and sustained release of SA, allowing twice-daily medication without increased fluctuations in SA concentrations.

Adult↗
PubMedDate not supplied

A method for MR quantification of flow velocities in blood and CSF using interleaved gradient-echo pulse sequences.

The aim of this study was to establish a rapid method for in vivo quantification of a large range of flow velocities using phase information. A basic gradient-echo sequence was constructed, in which flow was encoded along the slice selection direction by variation of the amplitude of a bipolar gradient without changes in sequence timings. The influence of field inhomogeneities and eddy currents was studied in a 1.5 T interleaved sequences for calibration and in vivo flow determination were constructed, and flow information was obtained by pairwise subtraction of velocity-encoded from velocity non-encoded phase images. Calibration was performed in a nongated mode using flow phantoms, and the results were compared with theoretically calculated encoding efficiencies. In vivo flow was studied in healthy volunteers in three different areas using cardiac gating; central blood flow in the great thoracic vessels, peripheral blood flow in the popliteal vessels, and flow of cerebrospinal fluid (CSF) in the cerebral aqueduct. The results show good agreement with results obtained with other techniques. The proposed method for flow determination was shown to be rapid and flexible, and we thus conclude that it seems well suited for routine clinical MR examinations.

Aorta↗
PubMedDate not supplied

Evidence for diabetic encephalopathy.

Auditory brain stem responses were recorded in 20 normoacoustic long-duration Type 1 diabetic patients (duration of diabetes 26 (range 13-46) years, age 44 (25-66) years) with peripheral neuropathy and retinopathy and in 19 sex-matched normoacoustic short-duration Type 1 diabetic patients (duration of diabetes 2 (0-6) years, age 23 (18-50) years) without clinical signs of neuropathy or microangiopathy. Abnormal brain stem auditory evoked responses were demonstrated in 40% of the long-duration and in 5.3% of the short-duration diabetic patients (p less than 0.01). Interpeak latencies Jv-JI and JIII-JI were significantly prolonged in both patient groups compared with the non-diabetic control group (p less than 0.01). Magnetic resonance imaging was performed in 16 of the long-duration patients and in 40 age-matched healthy volunteers on a whole body MR-scanner. Subcortical and/or brain stem lesions with abnormally high signals were seen in 69% of the long-duration Type 1 patients and in 12% of the healthy volunteers (p less than 0.02). Neuropsychological examination including 17 tests for intelligence and cognition were performed in the 20 long-duration Type 1 diabetic patients. The results indicated a performance close to that seen in a control group of healthy age-matched control subjects. Our study demonstrates that a considerable proportion of long-duration Type 1 diabetic patients suffering from retinopathy and peripheral neuropathy additionally have signs but no symptoms of central nervous system affection, diabetic encephalopathy.

Adult↗