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Biomedical subjects

B Karlsson

Publications and source records attributed to B Karlsson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Myelin basic protein in brains of rats with low dose lead encephalopathy.

Postnatal exposure of rats to lead has been shown previously to cause CNS hypo-myelination. Since rats intoxicated with lead often show retarded growth, the superimposed malnutrition, which as such can cause hypomyelination, may contribute to myelin deficit. In the present study control rats and lead exposed rats which did not have any retardation of growth were examined by radioimmunological assay of myelin basic protein (MBP) of homogenates of cerebrum and cerebellum at 30, 60 and 120 days of age. Lead was administered on postnatal days 1-15 by daily intraperitoneal injections of 10 mg lead nitrate/kg body weight. This lead dose results in light microscopically discernible hemorrhagic encephalopathy in the cerebellum of 15-day old rats, but does not induce growth retardation (Sundström et al. 1983). The controls were injected with vehicle only. The amount of lead in the blood and brain homogenates of lead-exposed and control rats 15-200 days old was estimated by atomic absorption spectrophotometry. Significant differences between the lead-exposed and control rats were not found in the cerebral or cerebellar content of MBP. Considering the results of previous investigations, the findings do not exclude a hypo-myelinating effect of lead, but they suggest that exposure to lead without concomitant malnutrition does not cause hypo-myelination in the cerebrum and cerebellum of the developing rat.

Aging↗
PubMed1986

On the composition and characteristics of microvessels isolated from the rabbit and bovine brain.

Brain capillaries (microvessels) were isolated from the rabbit and bovine brain. Extensive morphological examinations were performed at the light and electron microscopical levels. The relative contribution of endothelium (52%), basal membrane (32%) and pericytes (16%) to the composition of the microvessel was assessed. The ability of the endothelium from bovine brains to maintain a membrane potential, i.e. to accumulate the lipophilic cation [3H]TPMP, was shown. The transmitter catabolizing enzymes MAO and AchE were shown to be, and COMT and GABA-T not to be associated with the microvessel fraction isolated from rabbits.

4-Aminobutyrate Transaminase↗
PubMed1986

Moped and motorcycle accidents--similarities and discrepancies.

Injury patterns and epidemiologic data from 211 moped accident victims and 214 motorcycle accident casualties admitted to hospital over a 5-year period (1977-1981) have been analyzed and compared. The number of those injured in motorcycle accidents tripled; the number of moped accident victims slightly decreased in the period studied. Differences in injury pattern, sex ratio, cause of accident, and age distribution were noted. Among mopedists, head injuries were more common but these injuries decreased significantly after the adoption of helmet use laws for mopedists also in 1978. There were more females involved in moped accidents and the mean age was considerably higher among mopedists. Of those injured in moped accidents, 21% were 60 years old or older and accounted for 56% of fatalities in this group. The most frequent cause of moped accidents was collision with a car, and over turning or running off the road in motorcycle accidents. The difference in injury severity was unexpectedly small, although there was a tendency toward more severe injuries in motorcyclists. Moped accidents are so similar to motorcycle accidents that it seems unjustified to regard mopeds as harmless 'bicycles with a helper motor.' The need for formal registration, driving license, and helmet use laws for mopeds is apparent.

Accidents, Traffic↗
PubMed1985

Functional development of the visual system in normal and protein deprived rats. II. Morphometric and biochemical studies on adult optic nerve.

The optic nerve of normal (C) and protein deprived (PD) adult rats was examined by morphometry and biochemistry. The mean cross-sectional area of the optic nerve was reduced by 15% and the number of axons per unit area increased by 17% in the PD rats. Calibre spectrum analysis of axons revealed a reduction in median diameter from 0.49 micron in controls to 0.45 micron in PD rats. The number of axons with a diameter larger than 1 micron was reduced by 35% in PD rats. These reductions were probably due to a general reduction in size, since the calculated total number of axons in the optic nerve was almost identical in C and PD rats (126 X 10(3) and 124 X 10(3), respectively). The increased packing density of axons in the nerve was not only due to thinner axons. The biochemical measurements showed a marked reduction in myelin basic protein in the optic nerves of PD rats, without an alteration in the composition of the total protein. This confirms the persistent hypomyelination which has been reported previously in other malnutrition models. The possible relations between the structural and biochemical changes affecting optic nerve fibres and physiological findings on cortical visual evoked response and on optic nerve in vitro in PD rats are discussed.

Animals↗
PubMed1985

In vivo studies on amino acid transmitters in the central auditory system of the guinea pig.

The extracellular concentrations of endogenous amino acids were measured in vivo in the guinea pig cochlear nucleus during sound stimulation. The purpose was to explore whether certain amino acids might be employed as neurotransmitters by the auditory nerve. A dialysis sampling probe was used to collect a dialysate of the cochlear nucleus. The amino acids were determined fluorometrically after precolumn derivation and high-performance liquid chromatography separation. A short pulse of p-chloromercuryphenylsulfonate (p-CMS) was used to reduce the reuptake of amino acids. The concentration of glutamic and aspartic acid increased twofold to threefold during sound stimulation, while gamma-aminobutyric acid was unaffected. The results support a role for glutamic and/or aspartic acids as neurotransmitters in the auditory nerve.

4-Chloromercuribenzenesulfonate↗
PubMed1985

Soman intoxication and the blood-brain barrier.

Brain capillaries (microvessels) were isolated from rabbit brain. Morphological characterization revealed relatively pure fractions of microvessels consisting of the capillary endothelium, the basal membrane, and the pericyte. These fractions of brain capillaries show acetylcholinesterase (AChE) and monoamine oxidase (MAO) activity, but lack catechol-O-methyltransferase and GABA transaminase activity. Isolated brain capillaries together with samples of the brain parenchyma and serum were used to study the role of AChE present in the brain capillary wall in soman intoxication. The results showed this AChE to be less sensitive to soman inhibition than AChE of brain parenchyma. Serum and brain AChE recovered to some extent in soman-intoxicated rabbits given HI-6, whereas AChE present in the microvessel was even further inhibited. It is suggested that soman-induced vasospasm in rabbit brain may explain both the inaccessibility of capillary AChE to soman and also the unfavorable effect of HI-6 on this enzyme.

Acetylcholinesterase↗
PubMed1984

Cellular composition of primary cultures from cerebral cortex, striatum, hippocampus, brainstem and cerebellum.

Primary cultures from newborn rat cerebral cortex, striatum, hippocampus, brainstem and cerebellum were grown for 14 days. There was a linear relationship between the amount of material seeded and the protein content of the respective culture. The amount of tissue material seeded was selected so that the different cultures reached confluence at 6-7 days and contained similar amounts of protein when 7 and 14 days old. The cellular content was evaluated by astroglial markers, such as the glial fibrillary acidic protein (GFAp; alpha-albumin) and the S-100 protein, and by markers for other cells expected to be in the cultures (14-3-2 protein, macrophage acidic protein (MAP), alkaline phosphatase, myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP]. Astroglial-like cells represented 60-70% of the cells present in the different cultures. Quantitation of GFAp (alpha-albumin) showed similar amounts to be present in cultures from cerebral cortex, hippocampus and striatum; however, on lower levels expressed in soluble proteins than in the corresponding brain regions of adult rats. Brainstem of adult rat contained large amounts of GFAp (alpha-albumin), while low levels were found in brainstem culture. Also, phagocytic cells (macrophages), endothelial-like cells, mesenchymal-like cells, ependymal-like cells and oligoblasts were found. Neither mature neurons, nor oligodendroglial cells were observed. It is concluded that although there might be some differences in the degree of maturation or in the cellular composition of the various cultures, they could serve as a good model system for studying the characteristics of astroglial cells from various brain regions.

Animals↗
PubMed1984

Molecular size of myelin basic protein immunoactivity in spinal fluid.

The molecular size of myelin basic protein (MBP) immunoactivity in spinal fluid from patients with multiple sclerosis, acute stroke or who had gone through neurosurgery was determined by gel filtration. Gel filtration fractions were analysed for MBP by radioimmunoassay. Spinal fluid from all patients demonstrated a broad range of MBP immunoactivity. The neurosurgery and stroke cases had high MBP immunoactivity in the higher molecular range, around 67 000 daltons. The spinal fluid from MS patients had increased levels of low molecular size MBP immunoactivity, around 10-13 000 daltons. The results suggest that different forms of demyelinating processes give rise to various kinds of MBP fragments and/or different proteolytic activity on MBP within the spinal fluid space.

Acute Disease↗
PubMed1984

Cerebrospinal fluid proteins and cells in men subjected to long-term exposure to organic solvents.

Cerebrospinal fluid (CSF) was obtained from 17 men occupationally exposed to organic solvents and diagnosed as having a psycho-organic syndrome. Healthy volunteers and patients without neurological disorders were used as controls. The albumin ratio was increased in three heavily exposed men, indicating an increased passage of albumin over the blood-brain barrier. A slight monocytoid reaction was present in three of the subjects in the exposed group. Myelin basic protein and enolase activity were within normal limits. Isoelectric focusing of CSF-enriched proteins obtained by absorption chromatography showed alterations in nine out of 17 exposed individuals: The most prominent change was a relative increase of the protein band with Ip 4.7.

Adult↗
PubMed1983

Structural studies of cytochrome reductase. Subunit topography determined by electron microscopy of membrane crystals of a subcomplex.

Ubiquinol: cytochrome c reductase was isolated from Neurospora mitochondria as a protein-detergent complex and dissociated by mild salt treatment. Three parts were obtained and characterized. Firstly, a complex containing the subunits III (cytochrome b), IV (cytochrome c1), VI, VII, VIII and IX; secondly, a complex containing the subunits I and II; and thirdly, the single subunit V (iron-sulphur subunit). Membrane crystals were prepared from the cytochrome bc1 subunit complex and by combining tilted electron microscopic views of the crystals, a low-resolution three-dimensional structure was calculated. This structure was compared to that of the whole cytochrome reductase (previously determined by electron microscopy of membrane crystals). Protein density absent from the structure of the subunit complex was then attributed to the missing subunits according to their size and shape and their association with the phospholipid bilayer.

Crystallization↗
PubMed1983

Structural studies of cytochrome reductase. Improved membrane crystals of the enzyme complex and crystallization of a subcomplex.

Membrane crystals of mitochondrial ubiquinol: cytochrome c reductase of improved size and long-range order and of the cytochrome bc1 subcomplex have been obtained by a dialysis method. The enzyme--Triton X-100 complex was mixed with Triton phospholipid micelles and the Triton slowly removed by dialysis for 48 hours at pH 5.5 at room temperature or above. The effect of varying the pH and temperature on the shape, size and order of the crystals is described.

Crystallization↗
PubMed1983

Cellular enzymatic differentiation in brain vessels of normal and protein-deprived rats. Biochemical studies.

Brain capillary development was studied in normal and protein-deprived rats using the specific activity of alkaline phosphatase (EC 3.1.3.1) and gamma-glutamyl transpeptidase (EC 2.3.2.1) in whole brain homogenates and microvessels obtained by gradient centrifugation according to Orlowski et al. (1974). Pre- and postnatal protein deprivation was induced by a 50% reduction in the dietary protein content. The density of microvessel fragments changed during development. Most of the early developmental increase in the specific activity of both enzymes in whole brain homogenates of normal rats can probably be explained by a rapid formation of new capillary segments. The increase in specific activity of gamma-glutamyl transpeptidase in microvessels was interpreted as a sign of cellular differentiation. Protein deprivation resulted in reduced specific activity of both enzymes in whole brain homogenates of 30-day-old rats, probably as a result of the decreased length per volume of the cerebral capillary network at this age (Conradi et al. 1979a). Signs of impaired endothelial growth were also present in the protein-deprived rats since the distribution of microvessel fragments in the 30-day-old protein-deprived rats was similar to that in 3-week-old normal rats. The specific activity of alkaline phosphatase was decreased in the microvessel fractions of 30- and 96-day-old protein-deprived rats, apparently signifying an effect of the protein deprivation on the endothelial cells. These effects of protein deprivation on the brain capillary endothelial transport system may have negative consequences for growth and function in the brain.

Age Factors↗
PubMed1983

Three-dimensional structure of the regularly constructed surface layer from Synechocystis sp. strain CLII.

The isolated, outermost cell wall layer from Synechocystis sp. strain CLII is described using electron microscopy and Fourier reconstruction to study the three-dimensional structure of the proteins within the layer to a resolution of ca. 3 nm. This surface layer forms regular hexagonal arrays (a = b = 15.2 nm). The two-dimensional space group is p6. The monomer proteins form hexamers arranged around a central hollow cylinder. The linkers between the hexamers are of the delta type and are located approximately in the central section between the top and bottom of the protein layer.

Cell Membrane↗
PubMed1982

Radioimmunoassay of myelin basic protein. A methodological evaluation.

Three techniques for separating free antigen from antigen-antibody complexes have been applied to radioimmunoassay of myelin basic protein: cold ethanol precipitation of complexes, dextran-coated charcoal precipitation of free antigen, and second antibody precipitation of complexes. After optimization of the incubation and separation steps, the 3 methods were evaluated for precision and accuracy when applied to both spinal fluid and brain tissue homogenates. For determinations in brain tissue all 3 methods showed the same precision and gave largely the same values, though the ethanol method gave slightly lower levels. For spinal fluid the ethanol and dextran-charcoal methods gave the same values, but the double antibody method gave values only 1/3 as high. With spinal fluid, the precision of the dextran-charcoal method was poor compared with that of the other two. The double antibody method proved to be the method of choice for brain tissue samples, when the results of the incubation and separation steps, and the precision and accuracy of the determinations were taken into account. However, for an unknown reason values for spinal fluid were too low by this method. Therefore the ethanol precipitation method is recommended for spinal fluid samples and the double antibody method for brain tissue samples.

Animals↗
PubMed1982

Brain primary culture-- a characterization (part II).

Brain primary cultures from newborn rat hemispheres have been further characterized. THe cultures contained the glial fibrillary acidic protein (GFAp; alpha-albumin), as analyzed quantitatively. GFAp (alpha-albumin) increased in concentration during growth of cultures and during maturation of the intact rat brain. FITC-labelled antibodies against GFAp (alpha-albumin) reacted specifically with astrocyte-like cells. Theses cells were also positive after Rio-Hortega's silver carbonate staining for astrocytes. No myelin basic protein (MBP) was detected in cultures, neither by quantitative measurements nor by immunofluorescent histochemistry. Negative results were also obtained for the myelin specific enzyme 2', 3'-cyclic nucleotide 3'-phosphohydrolase (CNP), e. e. the enzyme was at the same level in the cultures of different ages as in 3-day-old rat hemispheres. However, in rat brain increasing concentrations of MBP and CNP were found during maturation. This means that no myelin and thereby probably no or few differentiated oligodendroglial cells were present in the cultures, where the predominate cell type was of astroglial nature.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗