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Biomedical subjects

I Johansson

Publications and source records attributed to I Johansson.

At least 181 records · Page 10Linked to original sources
PubMed1988

Significance of "ultra-early" rebleeding in subarachnoid hemorrhage.

Knowledge of the local incidence of aneurysm rupture permits the conclusion that almost every patient in the population of 933,800 persons served by the authors' institution who was stricken by this catastrophe and survived long enough to be transported was treated at this center (121 patients during 34 months). Of these, 9.1% were admitted late (greater than 72 hours after subarachnoid hemorrhage (SAH]; of the remaining cases, 94.5% were seen within 24 hours and 50% within 6 hours post-SAH. Of the 121 patients, 10% were neurologically devastated on arrival, a late operation was planned for 19%, and the earliest possible surgery and nimodipine administration was selected for 71%. In this latter group, 50% of the operations were begun within 24 hours and 76% within 48 hours post-SAH. Sixty percent of all mortality and morbidity could be linked to the initial aneurysm bleed. The remaining 40% could be ascribed to potentially avoidable causes of unfavorable outcome. No less than 9.6% of all patients admitted within 24 hours after SAH suffered from "ultra-early" rebleeding during transportation or preparation for operation. The mortality rate from such rebleeding was 7.4%, compared with the 9.1% combined mortality rate from complications and late ischemia.

Female↗
PubMed1988

Saliva concentrations of some selected proteins and glycoprotein markers in man after supplementary intake of beta-carotene.

Vitamin A has profound effects on cell biology, morphology and function of excretory cells. In the present study we investigated the effect of supplementation with beta-carotene (provitamin A) on the secretion of salivary glycoproteins and some antibacterial components. Eighty-nine men, drawn from a larger double-blind pilot study among Finnish men of a high socio-economic standard, participated in this study which lasted for 60 days. The men were allocated either to beta-carotene supplementation of 20 mg a day or to placebo treatment. At the end of the study samples of stimulated whole and parotid saliva were collected and examined for total protein as well as hexosamine, sialic acid, thiocyanate and the activity of salivary peroxidase. The secretion rate of whole saliva was calculated and the activities of lysozyme, a bacteria aggregating glycoprotein (BAGP) and secretory IgA were measured in parotid saliva. Significantly higher levels of beta-carotene, but not retinol, were found in serum and whole saliva in the beta-carotene group compared to the placebo group. Retinol or beta-carotene could not be detected in parotid saliva. No difference was found either in saliva secretion rate or in the composition of whole or parotid saliva between the beta-carotene and the placebo group.

Adult↗
PubMed1987

Per-operative angiography--a useful tool in cerebral aneurysm surgery?

The value of per-operative angiography in elective surgery for aneurysms in the anterior cerebral circulation is evaluated. A progressive decrease in the number of difficulties was observed and was correlated with the introduction and refinements of microsurgery. From 1980-1983 approximately 5-8% of the angiograms revealed technical details which, as elucidated in the Discussion, did not always seem to require surgical correction. No case of an aneurysm neck remaining patent was encountered during this period. Similarly, main arterial branches were found to be occluded on only a few occasions, whereas significant unoccluded remnants of the base of the aneurysm occurred in roughly 5% of the cases despite modern microsurgery. It is felt by the authors that angiographic control of the operative result is no longer required in every aneurysm case because of the options for adequate visual control offered by the microtechnique. With this background it is concluded that, despite the optimal technical conditions available, per-operative angiography cannot be universally recommended in aneurysm surgery because of the inherent complexity of the procedure. Instead, post-operative angiography is more appropriate as a routine procedure for follow-up of a variety of selected cases in which visual control was unsatisfactory.

Cerebral Angiography↗
PubMed1987

Saliva composition and caries development during protein deficiency and beta-receptor stimulation or inhibition.

We tested the hypothesis that a low protein diet (5%) would change the conditions for synthesis and release of protein from the salivary secretory cells and increase caries development. In addition, we tested whether the simultaneous use of a beta-adrenoceptor agonist or antagonist had an additive effect. After an experimental period of nine weeks the animals fed the 5% protein diet had lower body weights, saliva secretion rates and total protein secreted per minute than a control group fed a 20% protein diet. There were greater numbers of cariogenic streptococci on the teeth and the caries scores were higher in the rats fed the low protein diet than in the rats in the control group. The beta-receptor agonist, isoproterenol, given to rats fed the 20% protein diet, caused a reduction in protein concentration and amylase activity in saliva and a slight increase in caries development. Propranolol had no effect on either saliva composition or caries development.

Animals↗
PubMed1986

Hydroxylation of acetone by ethanol- and acetone-inducible cytochrome P-450 in liver microsomes and reconstituted membranes.

Acetone oxidation in rat liver microsomes was induced 5- or 8-fold by the treatment of the animals with ethanol or acetone, respectively. The apparent Km of the reaction was 0.9 mM, a value lower than the concentration reported for plasma acetone under starvation conditions. The major acetone metabolite was identified as acetol by GC-MS. Acetone oxidation in microsomes was inhibited by typical P-450 inhibitors as well as by compounds (e.g. imidazole) known to interact with the ethanol-inducible P-450 form. Antibodies against this P-450 isozyme were inhibitory for the reaction in rabbit liver microsomes and this isozyme was the only one that showed acetone hydroxylation activity in reconstituted membranes. Imidazole inhibited the conversion of [14C]acetone into low-Mr compounds (e.g. glucose) in vivo. It is suggested that the ethanol- and acetone-inducible P-450 make use of acetone as an endogenous substrate in the utilization of the compound for, e.g. glucose production under conditions of starvation and diabetic ketoacidosis.

Acetone↗
PubMed1985

Carbon tetrachloride-induced lipid peroxidation dependent on an ethanol-inducible form of rabbit liver microsomal cytochrome P-450.

Treatment of rats with ethanol or rabbits with either imidazole or pyrazole, agents known to induce the ethanol-inducible form of liver microsomal cytochrome P-450 (P-450 LMeb), caused, compared to controls, 3-25-fold enhanced rates of CCl4-dependent lipid peroxidation or chloroform production in isolated liver microsomes. No significant differences were seen when the rate of CCl4-dependent lipid peroxidation was expressed relative to the amount of P-450 LMeb in the various types of microsomal preparations. In reconstituted membranous systems, this type of P-450 was a 100-fold more effective catalyst of CCl4 metabolism than either of the cytochromes P-450 LM2 or P-450 LM4. It is proposed that the induction of this isozyme provides the explanation on a molecular level for the synergism seen of ethanol on CCl4-dependent hepatotoxicity.

Animals↗
PubMed1985

The effect of malnutrition on caries development and saliva composition in the rat.

The purpose of this study was to investigate the effect in rats of malnutrition on caries development and on some antibacterial substances in saliva. By gastric intubation, two groups of ten rats each were fed a liquid basic diet (100% diet), and two similar groups were fed the basic diet diluted with an equal volume of water to contain 50% of the nutrients of the basic diet (50% diet). One group on undiluted and one group on the diluted basic diet were offered sucrose as a supplement by mouth 17 times daily, using a programmed feeding machine, and the other two groups were offered starch in a similar manner. The extent and depth of the caries lesions were five times greater in the low-nourished (50% diet) sucrose group in comparison with the group given the undiluted diet supplemented with sucrose. The 50% diet group ate more frequently from the offered supplement. The 50% diet induced lower salivary lactoperoxidase activities, and there was an additive effect of starch as supplement. Higher concentrations of sIgA were found in the saliva of animals fed the 50% diet supplemented with sucrose than in those fed sucrose and the 100% diet. Significantly greater levels of sIgA and IgG were found in the saliva from the 50% diet-sucrose group than in the 50% diet-starch group. Plaque scores differed slightly but not significantly between the groups. The starch group receiving 100% diet showed a slightly lower level of S. mutans infection as compared with the 50% diet-starch group; the caries scores in the starch groups did not differ.

Animals↗
PubMed1985

Prospective evaluation of the accuracy of duplex scanning with spectral analysis in carotid artery disease.

Prospective evaluation of duplex scanning of the carotid vessels was performed over a 2-year period in 125 consecutive patients (249 vessels) with transient ischaemic attacks or minor stroke. Defining disease as a stenosis of greater than 15% reduction of the vessel diameter, with subgroups of 16-49% stenosis, 50-99% stenosis and occlusion, the sensitivity obtained was 96%, specificity 93% and accuracy 94%. With the use of linear multiregression analyses further subgrouping into 50-75% and 76-99% stenosis was performed. The best predictive variables were, in decreasing order, peak systolic velocity, late diastolic velocity and the difference between peak systolic and late diastolic velocity in the internal carotid artery. The additional periorbital Doppler examination caused a slight improvement in determination coefficient and diagnostic accuracy.

Adult↗
PubMed1985

Duplex scanning and periorbital pulsed Doppler in the diagnosis of external carotid artery disease: analysis of causes of error.

The external carotid arteries (ECA) were examined by duplex scanning in 123 consecutive patients with transient ischaemic attacks (TIA) and minor stroke. Two occlusions and five out of six high grade stenosis were correctly classified, yielding a sensitivity of 88% defining disease as stenosis greater than 50. Specificity was 94% and accuracy was 93%. Nine low grade stenosis (less than 50%) and six normal vessels were judged as high grade stenosis. A possible cause of this overestimation was a compensatory flow increase in the ECA caused by an occlusion or high grade stenosis in the internal carotid arteries (ICA), either on the same side or bilaterally. This was supported by the finding of a significantly (P less than 0.05) higher retrograde flow velocity in the ipsilateral supratrochlear arteries (STA) in patients with high ECA flow velocity, as compared to those with normal ECA flow. Thus in the evaluation of a possible ECA stenosis, the condition of the ICA should be considered in order to avoid overestimation of ECA lesions. The additional examination of flow direction and velocity in STA gives an indication as to whether or not an ECA stenosis might be present.

Adult↗
PubMed1984

Mechanisms of hydroxyl radical formation and ethanol oxidation by ethanol-inducible and other forms of rabbit liver microsomal cytochromes P-450.

The hydroxyl radical-mediated oxidation of 5,5-dimethyl-1-pyrroline N-oxide, benzene, ketomethiolbutyric acid, deoxyribose, and ethanol, as well as superoxide anion and hydrogen peroxide formation was quantitated in reconstituted membrane vesicle systems containing purified rabbit liver microsomal NADPH-cytochrome P-450 reductase and cytochromes P-450 LM2, P-450 LMeb , or P-450 LM4, and in vesicle systems devoid of cytochrome P-450. The presence of cytochrome P-450 in the membranes resulted in 4-8-fold higher rates of O-2, H2O2, and hydroxyl radical production, indicating that the oxycytochrome P-450 complex constitutes the major source for superoxide anions liberated in the system, giving as a consequence hydrogen peroxide and also, subsequently, hydroxyl radicals formed in an iron-catalyzed Haber-Weiss reaction. Depletion of contaminating iron in the incubation systems resulted in small or negligible rates of cytochrome P-450-dependent ethanol oxidation. However, small amounts (1 microM) of chelated iron (e.g. Fe3+-EDTA) enhanced ethanol oxidation specifically when membranes containing the ethanol and benzene-inducible form of cytochrome P-450 (cytochrome P-450 LMeb ) were used. Introduction of the Fe-EDTA complex into P-450 LMeb -containing incubation systems caused a decrease in hydrogen peroxide formation and a concomitant 6-fold increase in acetaldehyde production; consequently, the rate of NADPH consumption was not affected. In iron-depleted systems containing cytochrome P-450 LM2 or cytochrome P-450 LMeb , an appropriate stoichiometry was attained between the NADPH consumed and the sum of hydrogen peroxide and acetaldehyde produced. Horseradish peroxidase and scavengers of hydroxyl radicals inhibited the cytochrome P-450 LMeb -dependent ethanol oxidation both in the presence and in the absence of Fe-EDTA. The results are not consistent with a specific mechanism for cytochrome P-450-dependent ethanol oxidation and indicate that hydroxyl radicals, formed in an iron-catalyzed Haber-Weiss reaction and in a Fenton reaction, constitute the active oxygen species. Cytochrome P-450-dependent ethanol oxidation under in vivo conditions would, according to this concept, require the presence of non-heme iron and endogenous iron chelators.

Animals↗
PubMed1984

Studies of the effect of diet on saliva secretion and caries development: the effect of fasting on saliva composition of female subjects.

In the present investigation 11 females of normal constitution were subjected to a standardized fasting diet for 8 days. Three subjects dropped out early during the experimental period. Saliva and blood samples were collected before, during and after the fasting period. Serum analyses were made of some parameters often studied during undernutrition. As expected, values for creatinine and uric acid were increased. Secretion rate, pH, buffer capacity, electrolytes, total protein, carbohydrates, some antibacterial substances, the amount of Streptococcus mutans, total streptococci, and lactobacilli were determined in the saliva samples. The rate of plaque formation was also estimated. The effect of fasting on the measured parameters varied greatly among the individuals. Fasting caused a significant decrease in secretion rate, concentration of phosphate and sialic acid in stimulated whole saliva. There was no significant increase in concentration of any substance measured. The decrease of the ratio of sialic acid to protein indicates a disturbance of glycoprotein synthesis. In resting saliva the activity of a bacteria-aggregating glycoprotein appeared to be unchanged, whereas the decreases in thiocyanate concentration and lysozyme activity were statistically significant. Lactoperoxidase activities did not change significantly. The amount of IgA, IgG, IgM as well as the microbial counts showed no changes. The rate of plaque formation increased during fasting.

Adult↗
PubMed1984

Sexual and contraceptive experience among teenagers in Uppsala.

A questionnaire was offered to 181 sixteen-year-old boys (n = 88) and girls (n = 93) in different schools in the city of Uppsala. The questionnaire was introduced to the students by a nurse midwife during a regular lesson and included over 100 questions dealing partly with sexual education, attitudes towards sex and own experience of sex and contraception. Of the girls, 47% and of the boys, 31% answered that they had had intercourse. Twenty-eight per cent of the girls and 21.5% of the boys had had their first intercourse before the age of 15. Contraception was used at the first intercourse by 59% of the girls and by 70% of the boys. At the very first intercourse, the condom was the most commonly used contraceptive method. Increasing sexual experience changed the contraceptive pattern and at their last intercourse 48% of the girls were on the pill and 33% of the boys said that their girl friend was on the pill.

Adolescent↗
PubMed1983

Hydroxyl radical-mediated, cytochrome P-450-dependent metabolic activation of benzene in microsomes and reconstituted enzyme systems from rabbit liver.

The mechanism of benzene oxygenation in liver microsomes and in reconstituted enzyme systems from rabbit liver was investigated. It was found that the NADPH-dependent transformation of benzene to water-soluble metabolites and to phenol catalyzed by cytochrome P-450 LM2 in membrane vesicles was inhibited by catalase, horseradish peroxidase, superoxide dismutase, and hydroxyl radical scavengers such as mannitol, dimethyl sulfoxide, and catechol, indicating the participation of hydrogen peroxide, superoxide anions, and hydroxyl radicals in the process. The cytochrome P-450 LM2-dependent, hydroxyl radical-mediated destruction of deoxyribose was inhibited concomitantly to the benzene oxidation. Also the microsomal benzene metabolism, which did not exhibit Michaelis-Menten kinetics, was effectively inhibited by six different hydroxyl radical scavengers. Biphenyl was formed in the reconstituted system, indicating the cytochrome P-450-dependent production of a hydroxycyclohexadienyl radical as a consequence of interactions between hydroxyl radicals and benzene. The formation of benzene metabolites covalently bound to protein was efficiently inhibited by radical scavengers but not by epoxide hydrolase. The results indicate that the microsomal cytochrome P-450-dependent oxidation of benzene is mediated by hydroxyl radicals formed in a modified Haber-Weiss reaction between hydrogen peroxide and superoxide anions and suggest that any cellular superoxide-generating system may be sufficient for the metabolic activation of benzene and structurally related compounds.

Animals↗
PubMed1981

The mechanism of cytochrome P-450-dependent oxidation of ethanol in reconstituted membrane vesicles.

The mechanism of cytochrome P-450-dependent oxidation of ethanol has been investigated using reconstituted phospholipid vesicles containing purified preparations of rabbit liver microsomal NADPH-cytochrome P-450 reductase and cytochrome P-450 LM2. Incorporation of cytochrome b5 into the vesicles resulted in a 5-fold enhancement of cytochrome P-450-catalyzed O-dealkylation of 7-ethoxycoumarin, whereas the cytochrome P-450-dependent ethanol oxidation was slightly inhibited. Superoxide dismutase, added in increasing amounts to the vesicles, inhibited the formation of superoxide anions and, in a concomitant manner, also the production of acetaldehyde from ethanol in the system. Also horseradish peroxidase inhibited ethanol oxidation catalyzed by the vesicles; acetaldehyde formation and H2O2 formation decreased in a concomitant manner as the amount of the peroxidase was increased. Externally added hydrogen peroxide markedly stimulated cytochrome P-450-dependent ethanol oxidation, but not until the concentration of H2O2 reached 0.3 mM, whereas the hydroxyl radical scavenger mannitol completely inhibited the cytochrome P-450-dependent acetaldehyde production. Oxidation of ethanol was also accomplished using vesicles containing cytochrome b5 instead of cytochrome P-450 and in other systems regenerating superoxide anions, e.g. the xanthine-xanthine oxidase system and dihydroxyfumarate. The results are consistent with an iron-catalyzed Haber-Weiss mechanism for regeneration of hydroxyl radicals which subsequently react with ethanol, thereby giving the corresponding aldehyde.

Animals↗
PubMed1981

Comparison between directional Doppler and angiography in the diagnosis of internal carotid artery disease.

Directional Doppler examination (DD) with flow registration over the supraorbital and supratrochlear arteries and over the carotid artery in the neck was adopted to 99 carotid arteries in 56 patients without previous knowledge of angiography results, and thereafter DD and angiography findings were compared. On subgrouping of the angiography results into internal carotid artery (ICA) stenosis less than 50%, greater than 50%, and occlusion, a correct diagnosis was obtained by DD on 90 vessels (91%). All 11 ICA occlusions were correctly diagnosed by DD. The incorrect results obtained with DD were as follows: Four ICA stenosis less than 50% were classified as stenosis greater than 50%; four stenosis greater than 50% were classified as less than 50%; one stenosis greater than 50% was classified as occlusion. DD is a useful noninvasive screening method for the detection of occlusion and greater than 50% stenosis of ICA.

Carotid Artery Diseases↗