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Biomedical subjects

M Lindberg

Publications and source records attributed to M Lindberg.

At least 181 records · Page 10Linked to original sources
PubMed1984

Heterologous radioimmunoassay of monkey luteinizing hormone: a critical assessment.

Available reagents for the immunoassay (RIA) of luteinizing hormone (LH) in monkeys, including a cynomolgus (cynLH) tracer, an antiserum against human chorionic gonadotropin (hCG), and a rhesus standard (rhLH), were assessed using an in vitro bioassay and the RIA in connection with fractionation by high-resolution isoelectrofocusing. The data presented indicate that the RIA system represents a significant improvement over the ovine-antiovine system. Since, however, the sensitivity of the RIA is some 50 times less than that of the in vitro bioassay, and since the rhLH standard is heavily contaminated with FSH, it is felt that until the advent of a homologous RIA, the in vitro bioassay is the method of choice.

Animals↗
PubMed1983

DNA homology between the arsenate resistance plasmid pSX267 from Staphylococcus xylosus and the penicillinase plasmid pI258 from Staphylococcus aureus.

A 29.5-kb plasmid, pSX267, from Staphylococcus xylosus DSM 20267 was found to code for arsenate, arsenite, and antimony (III) resistance. The isolated plasmid was transformed into S. aureus, where the same resistances were expressed. It was of special interest to see whether pSX267 showed any DNA sequence homology with the well-studied penicillinase plasmid from S. aureus pI258, also conferring arsenate, arsenite, and antimony III resistance. By the use of the Southern blotting technique, it was found that DNA sequence homology exists in the region of arsenate, arsenite, and antimony resistance, in addition to the region where the origin of replication, the incompatibility, and the replication A function were mapped on pI258. This finding was confirmed by electron microscope heteroduplex analysis, which allowed a correlation between the genetic and physical maps of pI258 and pSX267. Duplex DNA was formed at the arsenate operon of pI258, with a length of 2.6 kb, and at the incompatibility and replication A region, comprising a length of 2.5 kb. Adjacent to this latter region, two small regions of DNA homology were present, with lengths of 0.2 and 0.27 kb. Both plasmids share approximately 20% DNA sequence homology. The DNA homology of the arsenate, arsenite, and antimony III resistance coding regions between pI258 and pSX267 indicate that these plasmid-determined resistance markers are highly conserved and distributed among different staphylococcal species.

Antimony↗
PubMed1983

Gene fusion vectors based on the gene for staphylococcal protein A.

Two plasmid vectors, containing the gene coding for staphylococcal protein A and adapted for gene fusion, have been constructed. These vectors will allow fusion of any gene to the protein A gene, thus giving hybrid proteins which can be purified, in a one-step procedure, by IgG affinity chromatography. As an example of the practical use of such vectors, the protein A gene has been fused to the lacZ gene of Escherichia coli. E. coli strains containing such plasmids produce hybrid proteins with both IgG binding and beta-galactosidase activities. The hybrid protein(s) can be immobilized on IgG-Sepharose by its protein A moiety with high efficiency without losing its enzymatic activity and they can be eluted from the column by competitive elution with pure protein A. The fused protein(s) also binds to IgG-coated microtiter wells which means that the in vivo product can be used as an enzyme conjugate in ELISA tests.

Base Sequence↗
PubMed1983

Gene for staphylococcal protein A.

The gene for protein A from Staphylococcus aureus was cloned into pBR322 in Escherichia coli. An immunoassay was used to detect production of the protein. Protein A produced in E. coli was found in the periplasmic space and was purified and concentrated by IgG-Sepharose affinity chromatography. DNA sequence assay of the gene revealed a region with the general features of a prokaryotic signal peptide and a fifth structural region homologous to the four repetitive regions found earlier by amino acid sequence determination of the mature protein. Upstream from the structural gene there is a possible promoter region and a ribosomal binding sequence typical of gram-positive bacteria. The initiation codon is TTG.

Base Sequence↗
PubMed1983

Elemental redistribution and ultrastructural changes in guinea pig epidermis after dinitrochlorobenzene (DNCB) exposure.

Energy dispersive x-ray microanalysis and transmission electron microscopy were used to study ultrastructural and chemical changes occurring in the keratinocytes at the primary irritant dinitrochlorobenzene (DNCB) reaction. The results of the microanalysis showed a similarity between dose- and time-dependent effects of DNCB and were in accordance with the ultrastructural findings. With increasing cell injury (as judged by the ultrastructure) there was an increasing loss of phosphorus, potassium, and magnesium from the cells and an increase of cellular calcium content. Sodium and chloride were only moderately changed. Results recorded when the skin was exposed to a weak DNCB dose were in accordance with a stimulation of the basal keratinocyte cell population.

Animals↗
PubMed1983

Variation in epidermal structure as function of different fixation methods. A stereological and morphological study.

Ultrastructural and volume variations in intact human epidermis due to differences in composition of the fixative have been investigated by electron microscopy and stereology. It was found that with glutaraldehyde as fixative variations in buffer osmolality in the range of 120-390 mosmol caused readily detectable changes in volume of the intercellular space and keratinocyte morphology. Also the epidermal Langerhans' cell was effected by variations in buffer osmolality. Three commonly used fixatives (glutaraldehyde, glutaraldehyde + paraformaldehyde, and osmium tetroxide) were found to result in different morphological and volume relations.

Adult↗
PubMed1983

Elemental changes at irritant reactions due to chromate and nickel in guinea-pig epidermis.

The present investigation was performed to examine the possibility of using energy dispersive X-ray microanalysis (EDX) to obtain information on epidermal reactions at irritant dermatitis. The elemental redistribution in the stratum germinativum and stratum spinosum of the guinea-pig epidermis after intradermal injection of a chromate and a nickel solution was studied in thick cryo-sections. The two solutions caused different changes in elemental content in both cell layers. Nickel sulfate caused a conspicuous decrease in K levels whereas Na and Cl were elevated in both cell layers. Potassium chromate caused an increase in Cl but lowered the P values. The result of this study show that it is possible to use EDX-analysis of thick skin sections to obtain information on physiologically relevant alterations in epidermis at irritant dermatitis.

Animals↗
PubMed1982

The presence of 7-hydroxychlorpromazine in CSF of chloropromazine-treated patients.

7-Hydroxychlorpromazine (7-OHCPZ) has been identified and quantified in CSF from chlorpromazine (CPZ)-treated schizophrenic patients. The level of the metabolite in CSF was similar to that of CPZ. In serum the amount of 7-OHCPZ was about 30% of CPZ. The concentration of 7-OHCPZ in csf was positively and significantly correlated to the serum level.

Adult↗
PubMed1982

Treatment of pharyngeal gonorrhea due to beta-lactamase-producing gonococci.

Between March 1978 and October 1980 seven patients with beta-lactamase-producing gonococci in the pharynx were treated wit spectinomycin of cefuroxime or both. One-day treatment with spectinomycin was effective in only one of six patients and with cefuroxime in only one of four patients. Prolonged treatment with cefuroxime was successful in all five cases so treated.

Cefuroxime↗
PubMed1982

The effect of occlusive treatment on human skin: an electron microscopic study on epidermal morphology as affected by occlusion and dansyl chloride.

The effect of occlusion on epidermal morphology was studied at electron microscopic resolution. the morphological changes recorded were relatively mild, though conspicuous, and consisted in dilatation of the intercellular space, appearance of cytoplasmic vacuoles and an oedematous change in the dermis. Stereological analysis showed that the dilatation of the intercellular space had a biphasic time-dependent course. Dansyl chloride applied under occlusion was shown to cause the same type of changes as did simple occlusion, but the changes appeared earlier.

Adult↗
PubMed1982

Reactions of epidermal keratinocytes in sensitized and non-sensitized guinea pigs after dichromate exposure: an electron microscopic study.

The reaction in epidermal keratinocytes in sensitized and non-sensitized, normal guinea pigs after dichromate exposure has been investigated by electron microscopy. The results of the investigation show that the morphological alterations in keratinocytes in irritant and contact allergic reactions to dichromate are of a nonspecific nature. This underlines the fact that morphological reactions in the keratinocyte are uniform. The reactions were dose- and time-dependent. The morphology of the contact allergic reaction to dichromate in the guinea pig is consistent with that described for DNCB.

Animals↗
PubMed1982

Studies on the cellular and subcellular reactions in epidermis at irritant and allergic dermatitis.

To determine the cellular and subcellular reactions of keratinocytes at contact dermatitis, transmission electron microscopy was used in combination with energy dispersive X-ray microanalysis. Stereology and optical diffraction were used as complements to electron microscopy for studies of the effects of variations in the preparation technique on the ultrastructure of epidermis. The morphological effects of an increased hydration of epidermis were assessed by the use of occlusive patch tests. It was found that the relative volume of the epidermal intercellular space and the ultrastructure of the epidermal cells (keratinocytes and Langerhans' cells) were directly dependent on the osmolality of the fixative vehicle if glutaraldehyde was used as fixative. Cellular volume and morphology did also depend on the fixative used. Variations in the volume of the intercellular space were also detected when the water transport through epidermis was impaired by occlusive treatment. In normal epidermis prolonged fixation times (4 weeks) did not affect the morphology of the keratinocytes. However, if the structure and function of the keratinocytes were affected by the application of a irritant substance (DNCB), a loss of electron dense material from the cells was detected within 3 weeks. The ultrastructural changes in the keratinocytes at the irritant chromate and DNCB reactions were of a non-specific nature and are in accordance with the changes described for other irritant agents in the literature. A few cells with the features of apoptosis were recorded. The allergic chromate reaction was found to be a combination of the irritant reaction and a marked inflammatory response. To correlate the ultrastructural alterations in the keratinocytes with the functional state of the cells, X-ray microanalysis was used to determine the elemental redistribution occurring at the irritant DNCB reaction. The results of the X-ray microanalysis showed a good correlation between dose and time dependent effects and with the ultrastructural changes. Cell injury in the keratinocytes lead to decreases in the cellular content of phosphorous, potassium and magnesium and an increase of cellular calcium. Sodium, chloride, and sulphur were only moderately changed. A stimulation of the basal keratinocytes was detectable when a weak DNCB dose was applied to the skin.

Adult↗
PubMed1981

Plasmid transfer and genetic recombination by protoplast fusion in staphylococci.

The experimental conditions for plasmid transfer and genetic recombination in Staphylococcus aureus and some coagulase-negative staphylococci by protoplast fusion are described. Protoplasts were prepared by treatment with lysostaphin and lysozyme in a buffered medium with 0.7 to 0.8 M sucrose. Regeneration of cell walls was accomplished on a hypertonic agar medium containing succinate and bovine serum albumin. Transfer of plasmids occurred after treatment of the protoplast mixtures with polyethylene glycol (molecular weight, 6,000) not only between strains of the same species but also between parents of different species, although at approximately 100 times lower frequency in the latter case. Recombination of the chromosomal genes in fused protoplasts required simultaneous treatment of the mixed protoplasts with polyethylene glycol and CaCl2. A method was developed for isolation of recombinants after fusion between mutants of S. areus carrying unselectable markers. Antibiotic resistance plasmids were introduced into the parental strains and used as primary markers to detect protoplast fusion. Chromosomal recombinants were found among the clones with both parental plasmids at a high frequency. The method appears to have simple applications in the construction of strains with multiple mutant characters.

Bacteriological Techniques↗