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Biomedical subjects

I Johansson

Publications and source records attributed to I Johansson.

At least 145 records · Page 8Linked to original sources
PubMed1992

Salivary flow and dental caries in Indian children suffering from chronic malnutrition.

Chronic protein-energy malnutrition during the period of growth and development causes permanent disturbances of salivary gland function and tooth structure. Moderate protein-energy deficiency also causes impaired saliva secretion rate and composition in the adult rat. These impairments have been shown to coincide with an increased incidence of dental caries. In the present investigation we studied the effect of chronic malnutrition on saliva secretion rate and susceptibility to dental caries in Indian children. It was found that chronic malnutrition reduced the secretion rate of stimulated saliva, but not that of unstimulated saliva. The salivary buffer capacity was continuously decreased as the secretion rate decreased with the level of malnutrition in the Indian children. The malnourished children developed increased caries. Thus, it could be concluded that chronic malnutrition in growing children enhances the cariogenic potential stemming from fermentable carbohydrates.

Body Height↗
PubMed1992

Comprehensive medical examination of a group of patients with alleged adverse effects from dental amalgams.

Mercury from dental amalgams does not seem to cause dose-related intoxications. However, animal studies have shown that high-dose exposure to mercury may support various types of immunologic reactions. Ten patients claiming that their symptoms were caused and aggravated by amalgam therapy were selected for a study of the effects of removal of one amalgam restoration followed by placing of a composite filling. Clinical symptoms and the result of laboratory tests were recorded. Six patients had contact allergies to metals, three of them to mercury ammonium chloride. The comparison of pre- and post-experimental test results showed significant reductions in p-IgE and dU-albumin and significant increases in p-C3d and dU-beta 2-microglobulin. There was no laboratory evidence of a direct toxic effect by mercury on the patients. The observed response by some of the studied factors to the low acute exposure to amalgam may imply that an activation of the immune system occurred.

Adult↗
PubMed1992

Platelet-derived growth factor potentiates phorbol ester-induced neuronal differentiation of human neuroblastoma cells.

Previous studies have shown that platelet-derived growth factor (PDGF) and PDGF receptors are expressed in the mammalian central nervous system and that primary cultured neuroblasts from rat hindbrain have functional PDGF beta-receptors. Here, it is shown that cultured human neuroblastoma cells express PDGF alpha- and beta-receptors, but not PDGF-A and PDGF-B chain mRNA. In contrast to alpha-receptor expression, beta-receptor expression appears to be associated with a mature neuronal phenotype. Under serum-free growth conditions, PDGF-AA and -BB induce a trophic and weak mitogenic response in SH-SY5Y neuroblastoma cells, showing that the PDGF receptors in these cells are functional. In combination with 12-O-tetradecanoylphorbol-13-acetate, all three PDGF isoforms induce sympathetic neuronal differentiation of the SH-SY5Y cells, as shown by morphology and by increased expression of the genes coding for growth-associated protein 43 and neuropeptide tyrosine, respectively. This indicates a potential role for PDGF in the development of sympathetic neurons in particular and of the nervous system in general.

Cell Differentiation↗
PubMed1992

CT showing early ventricular dilatation after subarachnoidal hemorrhage.

We performed a retrospective analysis of 398 patients with subarachnoidal hemorrhage (SAH) confirmed by CT. On the first CT examination the temporal horns were enlarged in 84%, the frontal horns in 32%, and the third ventricle in 21% of the patients. The amount of blood in the basal cisterns was highly correlated to dilatation of the temporal horns. The temporal horns were enlarged even when small amounts of blood were found in the cisterns. The frontal and temporal horns were dilated only when moderate or large amounts of blood were present in the cisterns. In 24 patients no blood was seen in the basal cisterns on CT performed within 5 days of the hemorrhage; none of the 3 patients with aneurysms showed normal temporal horns while 18 without demonstrable aneurysms had normal, and 3 had moderately dilated, temporal horns. Because the temporal horns cannot usually be seen at CT of healthy individuals, dilatation could be a useful sign in the diagnosis of SAH.

Adult↗
PubMed1991

Insulin-like growth factor I shifts from promoting cell division to potentiating maturation during neuronal differentiation.

SH-SY5Y neuroblastoma cells undergo neuronal differentiation and their proliferation is inhibited when they are treated with phorbol 12-myristate 13-acetate (PMA). Insulin and insulin-like growth factor I (IGF-I) are mitogens for the nontreated SH-SY5Y cells, whereas the proliferative response to such factor stimulation is lost upon differentiation, in spite of the fact that the receptors for insulin and IGF-I remain expressed and functional in the differentiated cells. Here we show that the PMA-induced differentiation of SH-SY5Y cells grown in a serum-free medium is strongly potentiated by nanomolar concentrations of IGF-I, as judged by morphology and markers for neuronal differentiation--e.g., neuropeptide tyrosine and growth-associated protein 43. Also, insulin and IGF-II potentiated the phorbol ester-induced differentiation, although less efficiently than IGF-I. Using blocking anti-receptor antibodies, it could be shown that the differentiation induced by these factors, in combination with PMA, was primarily mediated through the IGF-I receptor.

Blotting, Northern↗
PubMed1991

Acetone-regulated synthesis and degradation of cytochrome P450E1 and cytochrome P4502B1 in rat liver [corrected].

The regulation of CYP2E1 and 2B1 was studied by following mRNA levels, catalytic activities and the subcellular distribution of the apoproteins in rat liver 0, 6, 12, 24, 48 and 96 h after a single intragastric dose of acetone. No changes were observed in hepatic CYP2E1 mRNA levels at any time after acetone treatment, whereas rapid rises were observed in the microsomal amount of CYP2E1 protein and CYP2E1-catalyzed 4-nitrophenol hydroxylase and carbon-tetrachloride-initiated lipid-peroxidation activities. However, CYP2E1-dependent catalytic activities declined much faster than the immunodetectable CYP2E1 protein, suggesting that this cytochrome P-450 is inactivated prior to degradation. Similar results were seen in primary hepatocyte cultures. By contrast, concomitant changes in levels of CYP2B1 and CYP2B1-dependent O-depentylation of pentoxyresorufin were observed in the same microsomal preparations. Investigation of the degradative mechanism of both CYP2E1 and CYP2B1 by immunoquantitation of the proteins in lysosomes and by immunohistochemistry indicated their degradation via an autophagic-lysosomal pathway. The data suggest that CYP2E1 is acutely inactivated in the endoplasmic reticulum and that degradation of this isozyme occurs, at least in part, by the lysosomal route. By contrast, CYP2B1 is principally controlled at the level of synthesis.

Acetone↗
PubMed1991

Hormone controlled phosphorylation and degradation of CYP2B1 and CYP2E1 in isolated rat hepatocytes.

Addition of adrenalin to primary rat hepatocytes caused a 3- and 2-fold increase in [32P]-incorporation into CYP2E1 and CYP2B1, respectively. Adrenalin also increased the rate of CYP2E1 degradation at similar concentrations as needed for phosphorylation of the protein (r = 0.93), but did not influence the degradation rate of CYP2B1. Ethanol (75 mM) completely protected from adrenalin dependent phosphorylation and degradation of CYP2E1, but did not influence CYP2B1 on these parameters. Examination of para-nitrophenol hydroxylase revealed that ethanol stabilized the catalytically active form of CYP2E1. Insulin treatment caused a stabilization of CYP2E1, but did not affect CYP2B1 degradation. It is concluded that degradation of CYP2E1 is the subject of hormonal control, whereas CYP2B1 decomposition is accomplished in a different and a less regulated manner.

Animals↗
PubMed1991

Genetic analysis of the interethnic difference between Chinese and Caucasians in the polymorphic metabolism of debrisoquine and codeine.

The Far Eastern and Caucasian populations are strikingly different with respect to the debrisoquine/sparteine hydroxylation polymorphism. The number of poor metabolizers, as defined for Caucasians, is very low among Chinese and Japanese. We investigated the molecular basis for this difference by analysis of the CYP2D6 gene in 115 Chinese subjects, combined with phenotypic classification of codeine and debrisoquine metabolism. A correlation between the rates of metabolism of these two drugs and genotype, as analyzed by RFLP using XbaI, was observed among the Chinese. A high frequency (37%) of alleles indicative of gene insertions (reflected by XbaI 44kb fragments) was recorded in the Chinese, but was not associated with the poor metabolizer phenotype, as it is in Caucasians. PCR amplification of part of the CYP2D6 gene with mutation specific primers for CYP2D6A (29A) and CYP2D6B (29B) allelic variants revealed that the XbaI 44kb fragment in Chinese apparently contains a functional CYP2D6 gene, in contrast to the situation among Caucasians. The results provide a molecular explanation of the interethnic difference in the metabolism of drugs affected by the debrisoquine hydroxylation polymorphism.

Adolescent↗
PubMed1991

Coffee drinking and blood cholesterol--effects of brewing method, food intake and life style.

The strongest correlations between coffee consumption and serum cholesterol levels have been found in countries where people drink coffee brewed by mixing coffee grounds directly in boiling water (boiled coffee). In the present study of a population-based sample of 1625 middle-aged subjects (the Northern Sweden MONICA Study), approximately 50% of the participants were drinking boiled coffee, and 50% were drinking filtered coffee. Consumers of boiled coffee had significantly higher serum cholesterol levels than consumers of filtered coffee. Subjects who drank boiled coffee reported a higher intake of fat. A linear multiple regression analysis with serum cholesterol as the dependent variable confirmed that boiled coffee was an important independent determinant of cholesterol levels. We conclude that subjects who drink boiled coffee have higher serum cholesterol levels than those who drink filtered coffee, and that the most likely explanation for this finding lies in the type of brewing method.

Adult↗
PubMed1991

Acute radiation effects on saliva composition in rats with different vitamin A levels in serum.

Irradiation of the head and neck often causes loss of salivary gland function which may lead to severe oral discomfort. The effects of a single dose of 25 Gy given to rats with different serum levels of vitamin A were studied. The salivary secretion rate as well as concentrations of protein, hexosamine, amylase and electrolytes, and the activities of two antibacterial glycoproteins were measured. At an adequate level of vitamin A in the diet, irradiation significantly reduced whole saliva secretion rate, and decreased the concentration of salivary sodium, calcium and hexosamine as well as the activity of a glycoprotein agglutinating a serotype c strain of S. mutans. Peroxidase, amylase and potassium were not significantly affected. The reductions seen at an adequate level of vitamin A were not reduced by supplementation of excess dietary retinol. The damage caused by irradiation was enhanced by vitamin A deficiency as seen in the reduced protein and hexosamine concentrations.

Animals↗
PubMed1991

Escherichia coli in patients with renal scarring: genotype and phenotype of Gal alpha 1-4Gal beta-, Forssman- and mannose-specific adhesins.

The frequency of Escherichia coli with Gal alpha 1-4Gal beta-specific adhesins is reduced among children who develop renal scars. The adhesion-negative phenotype may be due to the absence of the pap DNA sequences which encode these adhesins or to a phase variation event induced by in vitro culture. In the present study the frequency of pap and pil homologous DNA was determined by dot blot analysis with probes specific for the respective sequence using E. coli strains from children with recurrent pyelonephritis with and without renal scarring. The frequency of pap was 79% in the strains isolated from the nonscarring group compared with 39% in the strains from the scarring group (P less than 0.001). The Gal alpha 1-4Gal beta phenotype was expressed by 89% of the pap-positive strains from the nonscarring group compared with 71% in the scarring group (P less than 0.05). In addition 13 of 77 of the pap-positive E. coli strains agglutinated sheep erythrocytes but not the Gal alpha 1-4Gal beta latex beads; a reaction attributed to reactivity with the Forssman glycolipid. DNA sequences homologous with pil were found in 95% of all strains and there was no significant difference between the nonscarring and the scarring groups. The low frequency of Gal alpha 1-4Gal beta specific strains in the scarring group was therefore due to the absence of pap-homologous DNA sequences and to a reduced rate of phenotypic expression among pap-positive scarring strains. There was no support for a relationship between type 1 fimbriae and renal scarring.

Acute Disease↗
PubMed1990

Transcriptional control of CYP2E1 in the perivenous liver region and during starvation.

Previous data indicate that the CYP2E1 gene is transcriptionally activated after birth, but that the expression of ethanol-inducible CYP2E1 protein, hereafter, is regulated by post-transcriptional mechanisms. The constitutive expression of CYP2E1 protein is restricted to the perivenous region of the liver lobule. Here we present results from in situ hybridization and run off experiments indicating that this regioselectivity is caused by a higher rate of gene transcription in the perivenous hepatocytes. We also show that transcription of the CYP2E1 gene is activated by starvation, indicating that also this P450 gene is under transcriptional control under certain physiological conditions.

Acetone↗
PubMed1990

Expression of the neuronal form of pp60c-src in neuroblastoma in relation to clinical stage and prognosis.

The expression of the protooncogene c-src has been studied in specimens of childhood tumors with special reference to neuroblastoma and other tumors of neuronal origin. For comparison c-src gene expression was studied in seven neuroblastoma and neuroepithelioma cell lines. The structurally distinct neuronal product of the gene, pp60c-srN, expressed during normal development in neuroblasts and neurons, was identified by immunoblotting technique together with the fibroblast form, pp60c-src. While pp60c-src was found in most tumors studied, the neuronal form was restricted to neuroblastomas (23 of 27) and retinoblastomas (3 of 3) and could not be detected in the other childhood tumors. A dominance of the neuronal form, pp60c-srcN, was exclusively found in the infant cases of neuroblastoma (9 of 12), estimated to have good prognosis. These results indicate that pp60c-srcN might be a diagnostic marker in primitive childhood tumors. When expressed in higher amounts than pp60c-src, pp60c-srcN may be a positive prognostic marker in neuroblastoma, especially useful in the evaluation of infants. In addition, lack of pp60c-srcN seems to be incompatible with low stage neuroblastoma.

Aging↗
PubMed1990

Central post-stroke pain--somatosensory evoked potentials in relation to location of the lesion and sensory signs.

Somatosensory evoked potentials (SEPs) were studied in 27 patients with central post-stroke pain and in 19 controls. A scoring system for SEP was used, in which increasing abnormalities rendered increasing scores. SEPs evoked by electrical stimulation of the median and tibial nerves were compared to perception thresholds for touch, vibration, innocuous and noxious temperature. All patients had reduced temperature sensibility, while the threshold for touch and vibration was abnormal in only 52% and 41%, respectively. Decreased touch and vibration sensibility had a high correlation with high SEP scores, while no correlation was found between reduced temperature sensibility and SEP. The patients with thalamic lesions had the most severely affected SEPs, the ones with lower brain-stem lesions were the least affected. The results support the notion that the SEP is dependent on the lemniscal pathways and that lesions of the spinothalamic pathways are crucial for the development of CPS.

Aged↗