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Biomedical subjects

S Nyström

Publications and source records attributed to S Nyström.

At least 37 records · Page 2Linked to original sources
PubMed1989

Topology and acylation of spiralin.

Of the 51 polypeptides detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the plasma membrane of the helical mollicute Spiroplasma melliferum, 21 are acylated, predominantly with myristic (14:0) and palmitic (16:0) chains. This is notably the case for spiralin, the major membrane protein of this bacterium, which contains an average of 0.7 acyl chains per polypeptide, attached very probably by ester bonds to alcohol amino acids. The amphiphilicity of spiralin was demonstrated by the behavior of the protein in charge-shift electrophoresis, its incorporation into liposomes, and its ability to form in the absence of lipids and detergents, globular protein micelles (diameter, approximately 15 nm). The presence of epitopes on the two faces of the cell membrane, as probed by antibody adsorption and crossed immunoelectrophoresis, and the strong interaction between spiralin and the intracytoplasmic fibrils show that spiralin is a transmembrane protein. The mean hydropathy of the amino acid composition of spiralin (-0.30) is on the hydrophilic side of the scale. Surprisingly, the water-insoluble core of spiralin micelles, which is the putative membrane anchor, has a still more hydrophilic amino acid composition (mean hydropathy, -0.70) and is enriched in glycine and serine residues. Taking into account all these properties, we propose a topological model for spiralin featuring a transbilayer localization with hydrophilic domains protruding on the two faces of the membrane and connected by a small domain embedded within the apolar region of the lipid bilayer. In this model, the membrane anchoring of the protein is strengthened by a covalently bound acyl chain.

Acylation↗
PubMed1989

Completely computer-focused ultrasound imaging. First clinical imaging results.

Completely computer-focused ultrasound imaging has been achieved using the UHB (ultrasound holographic B) method. This is a synthetic aperture method that combines ultrasonic holography and the conventional B-scan method. A wide-angle ultrasound burst (4 MHz) is transmitted into the object and the reflected echoes are measured as a function of the propagation time, but both the amplitude and phase angle are recorded, giving multiple one-dimensional holograms in a cross-sectional plane. This UHB data is rearranged to obtain one-dimensional wave fields, which represent the wave fronts reflected from each depth. The image is then reconstructed by propagating these wave fields backward to their original positions on the image using Fourier transform, a spectrum shift theorem, and inverse Fourier transform. The whole UHB image is obtained by calculating the intensity lines from these wave fields and by scanning these lines one by on the cathode ray tube (CRT) monitor. Following extensive laboratory testing with single and multielement transducers, special 32- and 64-element linear array transducers were fabricated, as was computer software capable of producing a UHB image in 40 seconds. Tissue imaging tests followed by clinical imaging of 30 patients showed that images obtained with this prototype compared favorably with those obtained by state-of-the-art conventional ultrasound scanners. The potential advantages of the new method are enhanced lateral resolution and the incorporation of phase information in tissue characterization. This would be important in diagnostic and intraoperative, especially neurosurgical, imaging.

Brain↗
PubMed1988

Acoustic neuroma surgery in northern Finland.

A series of 40 patients with acoustic neuromas were operated on using the suboccipital or the translabyrinthine approach. Some patients were operated on using both routes. The series extends back to 1977 and contain predominantly large tumours. There was no mortality in the translabyrinthine series of 14 patients. In the suboccipitally treated series of 29 patient, 3 were previously treated using translabyrinthine approach. In this series there was one death directly due to sequelae of neuroma extirpation and in another, additional causes were present. Preoperative facial pareses were frequent. There were several additional pareses in the translabyrinthine series and also several additional in the suboccipital series. Facial pareses were operated on by a plastic surgeon and they did not markedly detract from working capacity. Only 2 patients in the total series had small tumours and useful preoperative hearing. Cochlear function was preserved in them.

Adult↗
PubMed1987

Histopathological and immunohistochemical changes in neurosurgically resected epileptic foci.

Neurosurgical resection of an epileptic focus was performed in eleven patients suffering from drug resistant focal epilepsy. The clinical result was favourable in nine cases and corresponds to the earlier results. The routinely processed biopsy specimens obtained from the brain resections were stained with haematoxylin-eosin and with specific antisera to GFAP, S-100, NSE, laminin, and fibronectin using the peroxidase-antiperoxidase technique. The main pathological finding was gliosis in eight cases, neuronal degeneration in two cases, and a vascular malformation in one case. The anti-GFAP as a specific marker of astrocytes made the astroglial proliferation clearly visible, demonstrating an astroglial scar in four cases and a moderately to strongly increased amount of astroglial cells in another four cases. Anti-S-100 and anti-fibronectin are not as specific markers. They stained both neurones and glial cells with comparable results to that of anti-GFAP but with a lower specificity and sensitivity. Anti-NSE showed decreased amounts of neurones in most of the heavily gliotic lesions and also stained glial cells in some cases. Anti-laminin stained the pial and vascular basement membranes and revealed an increased vasculature in two cases. From these results, it appears that GFAP immunostaining is a highly demonstrative means for the visualization of astrogliosis in epileptic lesions and may be of help in identifying slight focal changes. An exact demonstration of neuronal loss or other neuronal changes still waits for a more specific marker than NSE. A favourable clinical outcome after neurosurgery seems to be associated with the patients showing a clearly gliotic brain lesion in one temporal lobe.

Adolescent↗
PubMed1987

Cloning and expression of Acholeplasma laidlawii membrane acyl proteins in Escherichia coli.

Many integral membrane proteins in Acholeplasma laidlawii are enriched in hydrophilic amino acid residues and covalently modified with fatty acids. In order to understand how these proteins are inserted and anchored in the bilayer, we have cloned several of the major A. laidlawii proteins in Escherichia coli: 900 recombinant clones containing 4-kbp DNA fragments, inserted into the BamHI site of the plasmid pAT 153, were screened with antibodies. With antimembrane antibodies, 26 positive clones were detected, and with a mixture of five different monospecific antibodies, another 7 clones were obtained. Immunological analysis of the colonies in situ verified that antigens for A. laidlawii membrane proteins D12, T2, T3, T4a, and unidentified proteins were produced in separate clones. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting showed several fragments [25 to 94 kilodalton (kDa)] for each of these proteins, some of which were even visible on Coomassie Blue-stained gels. It is concluded that A. laidlawii membrane proteins can be efficiently expressed in E. coli.

Acholeplasma laidlawii↗
PubMed1987

Amphiphilic properties of spiralin, the major surface antigen of spiroplasmas. A preliminary report.

Spiralin, a 28-kDa (kilodalton) polypeptide, is the major antigen of Spiroplasma citri and S. melliferum in which it usually represents more than 20% of total membrane protein. The amino acid compositions of the spiralins purified from both spiroplasma species unambiguously show that these proteins are homologous. In addition, several lines of evidence indicate that such a protein is present in the menbrane of S. apis. A 25-kDa polypeptide antigenically related to S. citri spiralin has also been purified from the membrane of the nonhelical variant ASP-1. The spiralin of S. melliferum B88 has been used as a model for extensive characterization. This antigen binds detergent under nondenaturing conditions, can be incorporated into liposomes, and forms protein micelles upon gentle removal of detergent. Digestion of the micelles with trypsin leads to the precipitation of an insoluble material containing a major polypeptide of 3.9 kDa. The amino acid composition of this fragment is different from that of intact spiralin. It is highly enriched in glycine and serine and, as an insoluble peptide, exhibits an unexpectedly high polarity index (PI = 51.4%). Screening for acyl proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection in the membrane of S. melliferum indicates that spiralin is actually acylated. This set of properties is evidence that spiralin is an intrinsic membrane protein and strongly suggests that acylation triggers or facilitates integration of the molecule into the lipid bilayer of the spiroplasma membrane.

Acylation↗
PubMed1986

Selective acylation of membrane proteins in Acholeplasma laidlawii.

In membranes of the cell-wall-less prokaryote Acholeplasma laidlawii most proteins are of the integral type. A substantial fraction of these proteins are enriched in hydrophilic amino acid residues. Approximately 20 different major as well as minor proteins were found to be covalently modified with acyl chains. The same set of proteins are acylated when cells are grown in different fatty-acid-supplemented media. In individual proteins the ratio of palmitoyl/oleoyl acyl chains was 12-14 times larger than the acyl chain ratio in polar membrane lipids. The transmembrane protein D12 has close to two acyl chains per molecule. Proteins T2 and T4a, localized in the outer and inner leaflet of the membrane, respectively, occur each as pairs with a difference in relative molecular mass within each pair of approximately 2000. Each of these proteins as well as the other acyl proteins, except the light form of T4a, has close to one acyl chain per molecule. The extent of acylation was increased for certain proteins and decreased for others by treatment with globomycin or phenethylalcohol. The relative amounts of the T2 and T4a pairs were affected by these drugs. It is concluded that the mechanism of acylation is different from that in Escherichia coli lipoprotein and Bacillus penicillinase. The mean hydrophobicity [Kyte & Doolittle (1982) J. Mol. Biol. 157, 105-132] of the A. laidlawii acyl proteins are similar to those of other bacterial acyl proteins but significantly lower than for non-acylated integral membrane proteins, supporting an anchoring function of the acyl chains. The number of membrane acyl proteins in A. laidlawii and two other mycoplasmas are at least twice that in other bacteria.

Acholeplasma laidlawii↗
PubMed1985

Use of the antimicrobial removal device prior to blood culture in patients on antibiotic therapy.

The efficacy of the antimicrobial removal device in facilitating isolation of bacteria from blood containing antibiotics was evaluated in a multicenter study. Blood specimens from 143 patients who had culture-proven septicemia and had been on antibiotic treatment for at least 24 hours were recultured with and without the aid of the device. Septicemia persisted in 33 of the patients and use of the device improved the isolation rates: 63% of the gram-positive bacteria and 32% of the gram-negative bacteria were isolated only with the aid of the device. Use of the device was an advantage in 10 of 13 cases where the antibiotic concentration in the bottles exceeded the MIC for the infecting microorganism but in only 5 of 19 cases where the concentration was lower than the MIC. It is concluded that the antimicrobial removal device may be useful in patients already on antibiotic treatment, but that its use is limited by the cost and the amount of work involved.

Adsorption↗
PubMed1985

Immunocytochemical characterisation of human pituitary adenomas.

Immunohistochemical and histological investigations were undertaken on 24 surgically-removed pituitary adenomas. By histology (haemalu-eosin staining), 7 chromophobe, 12 acidophil and 5 basophil pituitary adenomas were revealed. For immunohistochemical purposes the peroxidase-antiperoxidase technique was applied. Primary antisera against 10 hormones were used. By immunohistochemistry, 7 prolactin-containing, 2 TSH-containing, 2 GH-containing and 1 beta-endorphin-containing pituitary adenomas were identified. Furthermore, 1 mixed thyrotropic-prolactin human pituitary adenoma was detected. A possible connection between histological and immunocytochemical findings is discussed.

Adenoma↗
PubMed1983

Personality variations in population: intelligence.

The present study was designed to chart the distribution of cognitive factors in an adult population. The material consisted of a representative sample of persons aged 18-65 years, living in the county of Stockholm (except for the city of Stockholm) in 1970. The total selection was 3 064 persons. These persons were invited to a hospital for a health examination, covering both physical and mental health. Psychometric tests were included. In the study of cognitive factors the rate of non-response corresponded to 18.7% of the sample (males 20.7%, females 16.6%). The tool of examination was the Dureman-Sälde test battery. It is shown that men score rather higher than women in analytical and spatial but not in verbal ability. Analytical ability declines steadily throughout the age spectrum. Spatial ability shows a declining trend from he age group 36-45 years. Verbal ability is best in the age group 36-45 years and here the reduction in higher ages is very limited. A positive correlation of considerable degree exists between social group and the intelligence factors. This applies particularly to verbal and spatial ability and the overall measures. The connection with logical-inductive ability is quantitatively much less impressive. As regards verbal and spatial ability, there is an age-related tendency to a widened gap between social groups. Standardization for social group in tests is advocated in practical use.

Adolescent↗
PubMed1979

Depression: factors related to 10-year prognosis.

The 10 years' course of a series of 83 moderately severe depressions is presented, as well as factors governing the clinical and work prognosis. Depression was the fundamental disturbance in 75 cases during the index period. The depression was endogenous in 67 cases, reactive in eight, and neurotic in six cases. In the follow-up the drop-out from personal examination was 6.4%. Twenty per cent of the patients had been (almost) entirely free from symptoms of depression during the period of observation, 5% had been continuously depressive. There were no suicides. Twenty-seven patients felt some decrease in working capacity during the depressions, but only seven were unable to continue their previous work and three had changed work to prevent relapses. Fourteen of the patients had been sick-listed for more than 1 year of the observation period. Favourable factors for long-term course were: high intellectual capacity (for work prognosis, W), afraid of hurting others (W), white collar work (W), slight depression of mood during index period (for clinical course, C), favourable immediate outcome after index period (W). Unfavourable factors for long-term course were: low intellectual capacity (W), hysteroid personality (C), syntonic personality (W), asthenic personality, sensitivity to praise (C), tendency to feel under observation (W), and some symptoms during the index period: tendency to seclusion (C), ideas of reference (C), dryness of mouth (C), difficulty in falling asleep (C), dreamlike feeling (C), supplicating attitude (C). The implications of the results for nosology, care, and prevention of depressive states are discussed.

Adult↗
PubMed1975

Predisposition for mental syndromes: A study comparing predisposition for depression, neurasthenia and anxiety state.

A hypothesis of selective predisposition for drepression, neurasthenic syndrome and anxiety states has been tested in a prospective study. The primary material for the investigation consisted of 4,000 city inhabitants who had registered a private car. Almost all of these could be invited to a group investigation by questionnaire in the autumn of 1959. Out of those invited, 83% participated, and out of these, 3,019 were males (the secondary material). Six years later, the registers of public psychiatric out- and in-patient units in the city were examined as to the appearance in 1960 or later of the men in the secondary material. One hundred and fourteen of these men were found in the registers. For each of these men ten controls, matched for age, were chosen from the rest of the secondary material. Thirty-seven of the patients had had a depression and 17 a neurasthenic syndrome as the main diagnosis, and 17 had an anxiety state as the main or secondary diagnosis. As independent factors were chosen the Sjöbring personality factors sub-validity (psychasthenic traits), sub-stability (syntonia) and sub-solidity (hysteroid habitual attitude), as well as subclinical phenomena related to the neurasthenic, depressive and anxiety syndromes. It was not possible to show a specific predisposing power of the background factors investigated. Psychasthenic premorbid personality, however, was significantly related to depression, and also showed a strong tendency to an association with neurasthenic syndrome and anxiety states.

Anxiety Disorders↗