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Biomedical subjects

M Lindberg

Publications and source records attributed to M Lindberg.

At least 73 records · Page 4Linked to original sources

A fibrinogen-binding protein of Staphylococcus epidermidis.

The present study reports on fibrinogen (Fg) binding of Staphylococcus epidermidis. Adhesion of different S. epidermidis strains to immobilized Fg was found to vary significantly between different strains, and the component responsible was found to be proteinaceous in nature. To further characterize the Fg-binding activity, a shotgun phage display library covering the S. epidermidis chromosome was constructed. By affinity selection (panning) against immobilized Fg, a phagemid clone, pSEFG1, was isolated, which harbors an insert with an open reading frame of approximately 1.7 kilobases. Results from binding and inhibition experiments demonstrated that the insert of pSEFG1 encodes a specific Fg-binding protein. Furthermore, affinity-purified protein encoded by pSEFG1 completely inhibited adhesion of S. epidermidis to immobilized Fg. By additional cloning and DNA sequence analyses, the complete gene, termed fbe, was found to consist of an open reading frame of 3,276 nucleotides encoding a protein, called Fbe, with a deduced molecular mass of approximately 119 kDa. With a second phage display library made from another clinical isolate of S. epidermidis, it was possible to localize the Fg-binding region to a 331-amino-acid-long fragment. PCR analysis showed that the fbe gene was found in 40 of 43 clinical isolates of S. epidermidis. The overall organization of Fbe resembles those of other extracellular surface proteins of staphylococci and streptococci. Sequence comparisons with earlier known proteins revealed that this protein is related to an Fg-binding protein of Staphylococcus aureus called clumping factor.

Amino Acid Sequence↗

Aspects on the physiology of human skin: studies using particle probe analysis.

The cellular part of the skin, the epidermis, is a very thin structure, approximately 120 microns thick, a fact which has hindered the exploration of the physiology of the epidermis in normal and pathological conditions. An additional complication is the fact that the epidermis contains layers of cells at different stages of differentiation. Therefore, conventional physiological capillary probes cannot, with any satisfactory precision, be located within a specified cell of a specified layer of the skin in vivo. Hence, alternative ways for the exploration of skin physiology have been sought for. In the past, analysis of the elemental content of skin was done was done as bulk measurements, and surprisingly wide ranges of elemental content were recorded. The width of these ranges was most certainly due to the sampling methods used rather than the sensitivity of the chosen method of analysis. Also, these older measurements did not discriminate between the different strata, and therefore the information provided little if any substance for a functional analysis of processes involved in normal and pathological differentiation of the epidermis. Particle probes, however, have been able to overcome such methodological problems. Over a period of 15 years we have studied normal human skin, normal-looking, paralesional skin from psoriatics, and skin from persons suffering from atopic dermatitis using PIXE analysis. In recent years, trace elements have been shown to work as secondary messengers or regulatory substances. As an example, calcium (Ca2+) has proven to be a very important signalling substance in a great variety of cellular systems. Studies with the transmission electron microscope (TEM) as well as histochemical methods have allowed an understanding of the role of Ca2+ in the differentiation process of the epidermis. Ca2+ has also been shown to play an important role in apoptosis (programmed cell death), which is currently a hot subject for the obvious reason that the final differentiation step between the stratum granulosum level and the stratum corneum represents a particular aspect of programmed cell death. The importance of the balance between calcium and zinc in apoptosis has been clearly demonstrated in a number of cellular systems, but we have still to clarify the validity of topical treatment with Zn ointments in different skin conditions. Substantial iron (Fe) losses via psoriatic lesions were demonstrated more than two decades ago, and these data were given new meaning when we found that a more discrete loss occurs in clinically normal-looking psoriatic skin. Obviously, such findings stress the importance of understanding the relation between the elemental content and normal and abnormal physiology. The ultimate goal of particle probe studies is to provide an understanding of the formation of a mature stratum corneum with a functional barrier reflected in physiological/biochemical mechanisms behind the properties of changed skin in patients afflicted with skin disorders of genetic or constitutional origin. This paper aims to give an overview of the state of the art in skin physiology made possible through the use of particle probes.

Animals↗

Shot-gun phage display mapping of two streptococcal cell-surface proteins.

We have used a phage display shot-gun cloning technique to map the binding domains in two cell surface proteins from animal group C streptococci. The proteins, MAG and ZAG, have affinity for alpha (2)-macroglobulin (alpha (2)M), serum albumin and IgG. In this work, parts of cloned i mag and zag genes were randomly cloned into a phagemid vector, and recombinant phages expressing alpha (2)-M- or albumin-binding activity were isolated through panning against immobilized alpha (2)M or albumin. Analysis of the clones revealed two distinct alpha (2)M-binding sites in protein MAG and two slightly overlapping binding sites in protein ZAG. The minimal albumin-binding domain in protein ZAG, as deduced from the affinity selected clones, consisted of 42 amino acids. These results show that the phage display shot-gun cloning is a rapid and convenient way to characterize the binding site(s) in receptor proteins without any prior knowledge of their number, size, and localization.

Albumins↗

Methods for X-ray microanalysis of epidermis: the effect of local anaesthesia.

The effect of local anaesthesia on the elemental content of cells in human epidermis was studied by electron probe X-ray microanalysis. Local anaesthesia with lidocaine was given by intracutaneous injection within 1 min prior to taking a skin biopsy. Biopsies taken without local anaesthesia were used as controls. Lidocaine with or without adrenaline caused a significant increase in the concentrations of Na and Cl, and a decrease in the concentration of K in the cells of the stratum basale and the stratum spinosum, compared with the control samples. The presence of adrenalin in the anaesthetic did not change the effect of lidocaine. The effects of local anaesthesia have to be considered in planning and interpretation of clinical applications of X-ray microanalysis.

Adult↗

Functional expression of adhesive peptides as fusions to Escherichia coli flagellin.

An expression system for studying epitopes of adhesion proteins based on fusion of gene fragments into fliC(H7) of Escherichia coli is described. We constructed the system by an in-frame insertion of DNA fragments encoding one, two or three of the fibronectin-binding D repeats present in the fibronectin-binding protein A (FnBPA) of Staphylococcus aureus, into the fliC(H7) gene region encoding the variable domain of the H7 flagellin. The constructs were expressed by in trans complementation in the E. coli strain JT1 which harbours knock-out mutations for the expression of FliC as well as of the mannoside-binding fimbrial adhesin. The resulting chimeric flagella, which contained 39, 77 or 115 heterologous amino acid residues, efficiently bound soluble and immobilized human plasma and cellular fibronectin, and the binding was most efficient with the flagella containing the three D repeats of FnBPA. The chimeric flagella bound to frozen sections of human kidney and to cultured human cells. Antibodies raised against the chimeric flagella bound to Protein A-deficient S. aureus cells and inhibited the binding of staphylococci to immobilized fibronectin. We also expressed peptides, ranging in size between 48 and 302 amino acids, of the collagen-binding YadA adhesin of Yersinia enterocolitica. A fragment of 302 amino acids representing the middle region of YadA was needed for collagen binding. Chimeric flagellar filaments expressing hundreds of intimately associated adhesive epitopes offer versatile tools to analyze adhesin-receptor interactions and functional epitopes of adhesion proteins.

Adhesins, Bacterial↗

Prevalence of asthma symptoms in video and written questionnaires among children in four regions of Finland.

The aim of this study was to determine whether there are regional differences in the prevalence of childhood asthma in Finland. A secondary objective was to assess the concordance between a written and a video questionnaire on asthma symptoms. In 1994-1995, the self-reported prevalence of asthma symptoms in four regions of Finland was studied among 11,607 schoolchildren aged 13-14 yrs, as part of the International Study of Asthma and Allergies in Childhood (ISAAC). The ISAAC written and video (AVQ 3,0) questionnaires were administered in the school setting. The prevalences of any wheezing during the previous 12 months in the ISAAC video questionnaire were 10% in East Finland (Kuopio County, n=2,821), 12% in South Finland (Helsinki area, n=2,771), 12% in Southwest Finland (Turku and Pori County, n=2,983), and 11% in North Finland (Lapland, n=3,032). The prevalences in the ISAAC written questionnaire were 13, 20, 15, and 16%, respectively. The surveys were performed during winter, except in Helsinki where the survey was carried out mainly during the spring pollen season. During autumn, the prevalence in the written questionnaire in Helsinki was 16%. In multivariate analysis, boys had a lower prevalence than girls, and smokers a threefold higher prevalence than nonsmokers. In conclusion, the prevalence of childhood asthma is lower in Finland than in other European countries, and may be even lower in the eastern part of the country. In contrast to the results from some other European countries, prevalences were lower in the video than in the written questionnaire, which suggests that translating the word "wheezing" into other languages, including Finnish, may produce results that cannot be compared. The strong association of smoking with wheeze both in the video and written questionnaires should be considered in further analysis of the ISAAC study.

Adolescent↗

A collagen binding protein from Lactobacillus reuteri is part of an ABC transporter system?

The gene coding for a collagen binding protein from Lactobacillus reuteri NCIB 11951 was cloned and sequenced. A genomic lambda library was constructed and recombinant plaques were screened using antisera raised against purified collagen binding proteins from the same L. reuteri strain. The positive plaques were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis, which revealed the expression of a 29 kDa protein, which reacted with the antisera and bound 125I-labelled type I collagen. The sequence of the corresponding gene, cnb showed that the collagen binding protein has sequence similarities to the solute binding component of bacterial ABC transporters.

Amino Acid Sequence↗

A monoclonal antibody enhances ligand binding of fibronectin MSCRAMM (adhesin) from Streptococcus dysgalactiae.

A monoclonal antibody 3A10, generated from a mouse immunized with the Streptococcus dysgalactiae fibronectin (Fn) binding protein FnbA, was isolated, and its effect on ligand binding by the antigen was examined. The epitope for 3A10 was localized to a previously unidentified Fn binding motif (designated An) just N-terminal of the repeat domain which represents the primary ligand binding site on FnbA. Fn binding to Au was enhanced by 3A10 rather than inhibited. This effect was demonstrated in two different assays. First, in the presence of 3A10 the Au-containing proteins and synthetic peptide more effectively competed with bacterial cells for binding to Fn. Second, 3A10 dramatically increased the binding of biotin-labeled forms of the Au-containing proteins to Fn immobilized on a blotting membrane. Pure 3A10 IgG did not recognize the antigen by itself, and Fn was required for the immunological interaction between the antibody and the epitope. This induction effect of Fn was shown in both Western blot and enzyme-linked immunosorbent assay in which immobilized Au-containing molecules were probed with 3A10 in the presence of varying concentrations of Fn. Specificity analyses of 3A10 revealed that the monoclonal also recognized a ligand binding motif in a Streptococcus pyogenes Fn binding MSCRAMM but not the corresponding motifs in two related adhesins from Staphylococcus aureus and S. dysgalactiae. Furthermore, 3A10 stimulated Fn binding by S. pyogenes cells. These results together with subsequent biophysical studies presented in the accompanying paper (House-Pomepeo, K., Xu, Y., Joh, D., Speziale, P., and Höök, M. (1996) J. Biol. Chem. 271, 1379-1384) indicate that the ligand binding sites of Fn binding MSCRAMMs have little or no secondary structure. However, on binding to Fn, they appear to undergo a structural rearrangement resulting in a defined structure rich in beta sheet and expressing a ligand-induced binding site for antibodies such as 3A10.

Adhesins, Bacterial↗

Memory dysfunction in mild aphasics.

The effect of mild aphasia (n = 9), as a result of subarachnoid haemorrhage (SAH), was evaluated against one matched (sex, age, and education) control group suffering from SAH of unknown origin without aphasia, and against one matched healthy control group. According to aphasia testing (Reinvang & Engvik, 1980), criteria for a classical diagnosis were not met. Therefore, the patients were characterized as mild aphasics: They generally displayed intact audo-verbal comprehension and repetition abilities, and they demonstrated a fluent, spontaneous speech. However, they showed phonemic and semantic paraphasias, with self-corrections; a few patients displayed alexia and agraphia. Memory performance of these three groups was evaluated by a neuropsychological test battery, designed to tap various components of verbal memory function. From the results it was concluded that: (a) Short-term memory is impaired, as regards the phonological loop and the central executive in working memory, whereas maintenance rehearsal is unaffected, given that the demands on phonological coding is minimized, (b) long-term memory is also generally impaired, whereas long-term learning and forgetting by means of subject-performed tasks proceeds within a normal range. Impairments were hypothesized to reflect less efficient central executive functions of working memory, involving generation of less appropriate semantic codes and phonological representations, (c) mildly aphasic patients are not subjectively aware of their own memory deficits, and (d) aphasia classification by means of standard procedures do not sufficiently characterize the nature of a mildy aphasic patient's memory problems.

Adult↗

Different pathways in irritant contact eczema? Early differences in the epidermal elemental content and expression of cytokines after application of 2 different irritants.

The epidermal response to 2 different irritants, nonanoic acid (NAA) and sodium lauryl sulfate (SLS), was investigated with 2 different methods. NAA 80% and SLS 4% were applied under occlusion for up to 24 h. Elemental changes were determined in cryosections by x-ray microanalysis. Compared to unexposed skin a significantly higher sodium/potassium ratio was found after 6 h in NAA-exposed skin and a lower ratio in SLS-exposed. At 24 h both substances had induced similar changes, compatible with a cell injury. The findings demonstrate a time-dependent NAA and SLS response. With reverse transcription polymerase chain reaction, the mRNA expression of interleukin-1 alpha (IL-1 alpha), -1 beta (IL-1 beta), -6 (IL-6), and -8 (IL-8), tumor necrosis factor alpha (TNF alpha) and granulocyte macrophage colony stimulating factor (GM-CSF) in shave biopsies from irritated and unexposed skin was studied at 0. 4. 8 and 24 h. NAA, but not SLS, induced an increase in mRNA expression for IL-6 mRNA-expression for GM-CSF was increased after SLS exposure, but not after NAA. These findings indicate a time and substance dependent difference in the up-regulation of mRNA for different cytokines in epidermis during the first 24 h of the irritant reaction. This might be the effect of differences in the irritants action on the cell membranes, which is also reflected by the differences found in the elemental content at 6 h.

Adult↗

Fragrance contact dermatitis: a worldwide multicenter investigation (Part I).

OBJECTIVE: The aim of this study was to determine the prevalence of responses to selected fragrance materials in patients with suspect fragrance allergy and to evaluate risk factors and associations with such responses. The validity of using specific fragrance ingredients versus a mixture of fragrances was evaluated in terms of predicting allergy to different fragrance ingredients. METHODS: One hundred sixty-seven subjects were evaluated in seven centers worldwide with a fragrance mix, the eight ingredients in the fragrance mixture, six other well-known fragrance allergens, balsam of Peru, and 15 lesser studied fragrance materials. RESULTS: The age of the patients was 44.9 +/- 17.5 years (mean +/- SD). More than 85% were women. A relatively high proportion gave a past history of atopic disease. Facial eruptions (40%) and hand involvement (26.7%) were the most common topographic sites. All but 4 of the 35 fragrance materials produced a positive response in > 1%. A reaction to fragrance mix occurred in 47.3%. Seven of the 34 ingredients tested produced an allergic response in more than 10% of those tested. Men were more likely than women to exhibit a positive response to five fragrance ingredients. White persons were more likely to react to perfume mix (52.8% versus 25.3%) and certain ingredients in the mix than Asian persons. Allergy to benzyl salicylate was more common in Japan than in Europe or the United States. CONCLUSION: The age at which patients with perfume allergy present for evaluation is similar to that of other contactants. Atopic individuals may be overrepresented in this group of patients. Face involvement is likely. White persons are more likely to react to fragrance mix, whereas in Asian patients benzyl salicylate was a more frequent allergen. Fragrance mix corrected with 85.6% of positive responses to fragrance ingredients. The addition of ylang ylang oil, narcissus oil, and sandalwood oil to fragrance mix would be expected to pick up 94.2% with positive responses to fragrance materials; adding balsam of Peru increases this to 96%.

Adult↗

Peripheral blood neutrophil morphology reflects bone marrow dysplasia in myelodysplastic syndromes.

Dysplastic features of cells in peripheral blood and bone marrow were studied in 51 patients with myelodysplastic syndromes (MDS) to evaluate the significance of the degree of neutrophil granulation (G-score) and the percentage of pelgeroid polymorphs (ppp) in the peripheral blood, as indices of dysplastic changes in the bone marrow. There was a good correlation between peripheral blood and bone marrow findings, both for G-score figures (r = 0.92, P < 0.01) and ppp (r = 0.82, P < 0.01). Significantly lower G-score figures were found among patients with an increased percentage of bone marrow blasts (P < 0.05), while high ppp correlated with the presence of ring sideroblasts, the degree of bone marrow fibrosis, and findings of complex chromosomal abnormalities. Patients with a high degree of bone marrow dysplasia had significantly lower G-score (P < 0.01) and significantly higher ppp (P < 0.05) figures, than those with less pronounced myelodysplasia. In addition, extreme hypogranulation (G-score < 150) or very high ppp (> or = 20%) was generally a sign of bi- and tri-lineage dysplasia in the bone marrow. The results thus show that quantitative estimation of peripheral blood polymorph dysplasia by G-score figures and ppp seems to reflect the total degree of bone marrow dysplasia in MDS and may serve as a complement to bone marrow evaluation when the diagnosis of MDS is difficult.

Aged↗

Increased mRNA expression of manganese superoxide dismutase in psoriasis skin lesions and in cultured human keratinocytes exposed to IL-1 beta and TNF-alpha.

Because reactive oxygen species have been implicated in the pathogenesis of various hyperproliferative and inflammatory diseases, the mRNA expression of the antioxidant enzyme superoxide dismutase was studied in psoriatic skin tissue. By using reverse transcription-PCR we found similar expression of copper, zinc superoxide dismutase (CuZnSOD) in the involved vs. uninvolved psoriatic skin. In contrast, the level of the manganese superoxide dismutase (MnSOD) mRNA message was consistently higher in lesional psoriatic skin as compared to adjacent uninvolved skin and healthy control skin. Parallel investigation of those cytokines that are thought to be direct or indirect inducers of the MnSOD activity revealed an increased mRNA expression of IL-1 beta, TNF-alpha, and GM-CSF in lesional psoriatic skin. To study if these cytokines exert a direct effect on dismutase expression in epidermal cells, human keratinocytes in culture were challenged with IL-1 beta, TNF-alpha, and GM-CSF. It was found that IL-1 beta and TNF-alpha, but not GM-CSF, induced the mRNA expression of MnSOD, and an additive effect was demonstrated for the two former cytokines. Further, the expression of both CuZnSOD and MnSOD transcripts was similar in cultured keratinocytes maintained at low differentiation (low Ca2+ medium) and cells forced to terminal differentiation (by high Ca2+ medium). Our results indicate that the abnormal expression of MnSOD mRNA in lesional psoriatic skin is not directly linked to the pathologic state of keratinocyte differentiation in the skin. It seems more likely that the cutaneous overexpression of MnSOD in psoriatic epidermis represents a protective cellular response evoked by cytokines released from inflammatory cells invading the diseased skin.

Adult↗