Biomedical subjects

M Lehto

Publications and source records attributed to M Lehto.

At least 109 records · Page 6Linked to original sources

PubMed1986

Human epidermal Langerhans cells and peripheral blood monocytes. Accessory cell function, autoactivating and alloactivating capacity and ETAF/IL-1 production.

We compared the functional capacities of human epidermal Langerhans cells (LC) and peripheral blood monocytes. Epidermal sheets were obtained by a suction blister device. After enzymatic treatment LC were enriched by attaching them to IgG-located erythrocyte monolayers. On a per cell basis, LC were several times more efficient accessory cells than monocytes in augmenting nickel-and tuberculin (PPD)-induced T-cell proliferation. In mixed cell cultures LC stimulated both autologous and allogeneic T cells, whereas monocytes stimulated only allogeneic cells. In addition, LC were significantly more potent allogeneic stimulators than monocytes. Although monocytes were weaker accessory cells and allogeneic stimulators than LC, they induced higher interleukin 1 (IL-1) activities than LC-enriched or LC-depleted cells. These results indicate that there are functional differences between LC and monocytes and that antigen presentation and mediator secretion are not correlated.

Antigen-Presenting Cells↗

PubMed1986

Bacteria are polyclonal T-dependent stimulants of immunoglobulin formation.

Various gram-positive and gram-negative bacteria were tested for their ability to induce antibody secretion in human blood cell cultures. Total and specific immunoglobulin levels in the culture supernatants were quantitated with enzyme-linked immunosorbent assays (ELISA). All the twelve strains used stimulated IgM and IgG secretion in adult mononuclear cell cultures. With the four strains tested, also umbilical cord blood cells produced IgM. Specific antibodies directed against two bacteria were sought in adult and newborn cell culture but none were found. Bacterium-induced antibody synthesis thus seemed to be polyclonal. Experiments with purified T and B lymphocytes showed that bacterium-driven antibody formation was T-cell dependent.

Antibodies, Bacterial↗

PubMed1986

Cell-mediated and humoral immunity to mumps virus antigen.

In the present study, cell-mediated and humoral immunity to mumps virus was investigated. The study population consisted of 25 subjects of whom 17 were initially seropositive for mumps. Serum antibody levels and lymphocyte blast transformation activity were measured before and after vaccination with inactivated vaccine. In addition, the subjects were skin tested and HLA-typed. Significant antibody responses, measured by enzyme-linked immunosorbent assay (ELISA), were observed after vaccination in all immunoglobulin classes. However, the elevation in antibody levels was usually transient in both seronegative and seropositive subjects. The IgA response was significantly higher in the seropositive than in the seronegative group, but no such difference was found in IgM or IgG antibodies. Vaccination also caused a significant but transient rise in lymphocyte blast transformation activity. Transformation results parallelled skin-test results and seropositivity, but not antibody levels, in the seropositive group. Pronounced IgA reactivity was significantly associated with Dw3 and Dw4 (DR3 and DR4) antigens. No HLA association was observed in IgG or IgM levels or in transformation activity.

Antibodies↗

PubMed1986

Polyclonal response of human lymphocytes to Chlamydia trachomatis.

The mitogenicity of Chlamydia trachomatis was investigated. Umbilical cord blood cells from healthy newborns were used. These cells were stimulated in cultures with partially purified C. trachomatis elementary bodies. Proliferation of cultured lymphocytes and secreted immunoglobulins and leukocyte migration inhibitory factor were measured in the culture supernatants. Our results showed that C. trachomatis is able to elicit polyclonal antibody, lymphokine, and DNA synthesis.

Antibodies, Bacterial↗

PubMed1986

Polyclonal antibody formation of human lymphocytes to bacterial components.

The capacity of various bacterial components to induce antibody formation in human lymphocyte cultures was studied in the present investigation. Antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA). Lipopolysaccharide (LPS), bacterial cell walls (CW, isolated from Bacillus subtilis and Staphylococcus aureus Wood 46) and peptidoglycans (PG) appeared to stimulate IgM, IgG and IgA secretion, whereas lysozyme-solubilized PG and teichoic acids (TA) were ineffective. Also, umbilical cord blood lymphocytes produced IgM after stimulation with LPS, CW and PG. Coculture experiments with purified lymphocytes and monocytes indicated that B-cell differentiation was dependent on both T cells and monocytes, and that T-cell derived factors could derived factors could partially substitute for T cells.

Adult↗

PubMed1986

Resection of the palmaris longus tendon in surgery for Dupuytren's contracture.

The present investigation presents preliminary results of the operative method, where resection of the palmaris longus tendon is combined with regional fasciectomy in the treatment of Dupuytren's contracture. This procedure was developed to prevent recurrence which has been the biggest problem in the treatment regardless the surgical methods employed. The investigation included 70 consecutive patients (80 hands) treated for Dupuytren's contracture; the mean follow-up time was 47 months (62 patients). 96% of the recurrences occurred during the first two years. 42 hands were treated with regional fasciectomy and in these 18 recurrences (43%) were observed. Recurrences were found only in 23% (6/26) of the patients in whom the palmaris longus tendon was eliminated. Following resection of the palmaris longus tendon recurrences manifested themselves mainly in the fingers in the nodular cutaneously fixed form. From the promising results and absence of side effects of resection of the palmaris longus tendon the procedure can be recommended combined with surgical treatment of Dupuytren's contracture.

Adult↗

PubMed1985

Changes in intramuscular collagen and fibronectin in denervation atrophy.

The distribution of collagen types I, III, and V and fibronectin was investigated by means of immunofluorescent techniques in denervated and normal rat skeletal muscle. During a period of 28 days, a distinct atrophy developed in the denervated gastrocnemius muscle and was accompanied by an increase in types I and III collagen in the endomysium and perimysium. The amount of type V collagen showed little change, whereas fibronectin increase closely parallelled types I and III collagen. The results indicate that denervation atrophy in muscles is accompanied by striking fibrotic changes due to mesenchymal types I and III collagen.

Animals↗

PubMed1985

Endoneurial fibrosis following nerve transection. An immunohistological study of collagen types and fibronectin in the rat.

Indirect immunofluorescent techniques with antibodies to type I, III, and V collagens and fibronectin were used to study rat sciatic nerve tributaries after transection with intact contralateral nerves as controls. Codistribution of type I and III collagens characterized the epineurium of normal nerve. In the perineurium, however, type I collagen was absent, but type III and V collagens and fibronectin were detected. Type I and III collagens were codistributed in the endoneurial stroma where a homogeneous staining by antibodies to fibronectin was also observed. During the 4-week observation period after transection the perineurium reacted by slight thickening which was most clearly demonstrated by staining with antibodies to fibronectin and to type V collagen. A widening of the type I-negative cleft also occurred. Endoneurial, type V collagen-positive cuffs around the nerve fibers became disorganized, and a concomitant increase of the stroma containing type I and III collagens and fibronectin was observed. The codistribution of the fibrous collagen types appeared similar in normal epineurium and endoneurium. Type V collagen was located in the perineurium and in endoneurial cuffs surrounding the nerve fibers. The present data indicate that collagen accumulation takes place in the perineurium and endoneurium of transected nerve. The cell type responsible for the synthesis of the connective tissue material is discussed.

Animals↗

PubMed1985

Characterization of the perivascular reticulin network in a case of primary brain lymphoma. Immunohistochemical demonstration of collagen types I, III, IV, and V; laminin; and fibronectin.

The character of the silver positive reticulin network was analyzed with immunofluorescence and immunoperoxidase methods in an intra vitam diagnosed case of primary brain lymphoma. The network was shown to contain connective tissue proteins rich in hexose-sugars, such as type III collagen (classical "reticulin"), basal lamina constituents type IV collagen and laminin, pericellular type V collagen, as well as fibronectin (protein involved in cell adhesion). On the other hand, very little of the fibrous type I collagen was discernible. Similarly as the silver positive network, the immunohistochemically demonstrable reticulum seemed to hold the cells in the perivascular location, and once it was broken diffuse spread into the tissue occurred. Since malignant cells of B-lymphocyte origin are not known to synthesize so-called reticulin, it is suggested that the network in primary brain lymphomas is produced by cells in the brain parenchyma (possibly pericytes or astrocytes) as a protective attempt to restrict the spread of foreign cells into the brain.

Brain↗

PubMed1985

Skeletal muscle injury--molecular changes in the collagen during healing.

Changes in the collagen types and cross-linking of granulation and scar tissue in the injured site of partially ruptured gastrocnemius muscle were studied after a reproducible contusion injury to the left calf of a rat. In normal i.m. collagen the proportion of Type I collagen was considerably higher than Type III. Following injury there was a rapid increase in the proportion of Type III collagen reaching a maximum at 5 days after injury. After a further 2 days the proportion of Type I had increased significantly resulting in a decrease of the Type III/I ratio to below that of the control. However, as healing progressed there was a gradual shift back to the Type III/I ratio for normal i.m. collagen. The collagen produced in response to an injury was initially stabilized by the stable keto-imine cross-link hydroxylysino-5-keto-norleucine, characteristic of embryonic collagenous tissues. The proportion of the stable keto-imine cross-link gradually decreased, and a reversion to the cross-link pattern of normal uninjured i.m. collagenous connective tissue occurred towards the end of the 42-day follow-up period. The present biochemical study demonstrates that during the early phases of the repair process there is a reversion to the collagens typically present in high proportions in embryonic dermal connective tissue. This suggests that the fibroblasts have the ability to modify their product expression under varying circumstances. The study also demonstrates the importance of collagen cross-linking in determining the tensile strength of collagen fibre during the repair process.

Animals↗

PubMed1985

Collagen and glycosaminoglycan synthesis of injured gastrocnemius muscle in rat.

The synthesis of collagen and glycosaminoglycans in a partially ruptured gastrocnemius muscle were studied in 30 rats by giving a single 3H-labelled proline and 14C-labelled glucosamine injection intraperitoneally 2-21 days after a standard transverse contusion injury induced to the left calf of the animals. Both injured and contralateral uninjured gastrocnemius muscles were cut into four analogous 5-mm thick transverse pieces using the center of injury as a site for the middle incision in the injured muscle. The muscle slices were homogenized, dialyzed and then burned in a sample oxidizer which automatically divides the two radioisotopes into two different sample flasks. The radioactivities were measured using a liquid scintillation spectrometer. The content of glycosaminoglycans within the site of injury increased to a maximum 5 days after trauma, and decreased in amount thereafter. The uptake of 3H-proline indicating the synthesis of collagen was very low 5 days after trauma but increased to a maximum between the 10th and 14th day; more intensively in the proximal border of the injury than in the distal one. The uptake decreased again in amount 21 days after trauma. Burning of an in vivo radioactively labelled sample in a sample oxidizer provides a simple method in determination of the two radioactive isotopes as indicators of two main components of granulation and scar tissue.

Animals↗

PubMed1985

Collagen and fibronectin in a healing skeletal muscle injury. An immunohistological study of the effects of physical activity on the repair of injured gastrocnemius muscle in the rat.

The presence of the connective tissue components fibronectin and the different types of collagen was demonstrated by histological and immunohistological methods in the granulation and scar tissue of a healing injury in rat muscle. The effects of physical activity on granulation tissue production, scar formation and muscle regeneration at various stages of healing were studied. It was shown that immobilisation after injury accelerates granulation tissue production, but if continued too long, leads to contraction of the scar and to poor structural organisation of the components of regenerating muscle and scar tissue. However, a certain period of immobilisation, about five days for rat muscle, is required to allow newly-formed granulation tissue to cover the injured area and to have sufficient tensile strength to withstand subsequent mobilisation. This mobilisation, at the correct interval, seems essential for the quicker resorption of scar tissue and the better structural organisation of the muscle.

Animals↗

PubMed1985

Intraperitoneal hepatic bile duct fistula following blunt abdominal contusion.

Injuries to intrahepatic biliary ducts rarely cause severe clinical manifestations in context with blunt abdominal trauma. A case with mild symptoms and signs, but slowly developing bile peritonitis due to posttraumatic intraperitoneal hepatic bile duct fistula is described here. A young girl sustained a blunt contusion on the right lower thoracoabdominal region by the handle bar of a bike. A week after the accident ultrasonography revealed fluid under the liver. The patient showed no signs of peritonitis but had occasional shoulder pain. At laparotomy 200 ml of biliary fluid was drained from the subphrenic space, and excoriation was observed on the upper surface of the liver. A second operation was necessary due to continuous bile leakage via the drain in the subphrenic space and a bile-fistula was demonstrated by contrast x-ray examination. A local resection of the liver was performed and the intrahepatic bile duct fistula closed by a ligature. The postoperative course was then uneventful and the patient was symptomfree on examination six months after the accident.

Abdominal Injuries↗

PubMed1984

Lymphocyte bacterial rosette test: methodological details and effect of metabolic inhibitors and divalent cations.

Lymphocytes bind certain bacteria. This property has been utilized in the lymphocyte bacterial rosette assay to identify T and B cell subsets. Here we determined the optimum conditions for the assay, studied the effect of metabolic inhibitors and divalent cations and compared bacterial rosette-forming lymphocyte subpopulations with those defined with monoclonal antibodies. The strains used were Brucella melitensis, Bacillus subtilis, Staphylococcus aureus and Escherichia coli. Optimum attachment was obtained at 4 degrees C in 6% BSA with ultrasonicated bacteria. Pretreatment of lymphocytes with the microfilament-disruptive drug cytochalasin B suppressed the binding of bacteria, whereas colchicine (inhibitor of microtubules), puromycin (inhibitor of translation), sodium azide (inhibitor of oxidative phosphorylation) and 2-deoxyglucose (inhibitor of glycolysis) had no effect. Divalent cations were required for the attachment of bacteria. B. melitensis bound to DR-positive cells, whereas the other bacterial strains rosetted OKT4- OKT8- and DR-positive cells without exhibiting helper or suppressor T cell or B lymphocyte specificity.

Antibodies, Monoclonal↗

PubMed1984

Collagen types and fibronectin in the uterine muscle of normal and hypertensive pregnant patients.

Specimens from the uterine wall were obtained from 16 patients at 31 to 40 weeks of pregnancy: 10 underwent surgical procedures for a hypertensive disorder and six for abnormality of the birth canal or faulty presentation. Collagen types I, III, and V and fibronectin antibodies were used for immunohistologic studies. Collagen types I and V were located mainly around single cells, but type III and fibronectin were found mainly around cell bundles. Collagenous structures in the uterine muscle of patients with hypertensive disorder in pregnancy were torn. Abundant fibronectin fluorescence was detected in the lobuli within the disrupted tissue. Disruption of the uterine structure correlated with the amount of urinary protein excreted.

Adult↗

PubMed1984

The distribution of types I, III, IV and V collagens in penetrant lesions of the central nervous system of the rat.

The presence and distribution of types I, III, IV and V collagens within open lesions in the rat cerebrum have been demonstrated by immunofluorescent techniques. In the adult animal, types I and III collagens can be identified in the cicatrix from eight days onwards. Types IV and V collagens occur in the basement membrane of the glia limitans formed between the neuropile and the cicatrix and in the basement membranes of the blood vessels. In neonatal animals, less than eight days old at operation and allowed to recover for eight days, no type I or III collagens occur in the lesion and no types IV and V are present along the edge of the neuropile, because a glia limitans is not formed. In animals operated on when eight days old, the adult response is found in the cortex only, but when 16 days old the full adult response occurs in all parts of the lesion.

Animals↗

PubMed1984

Distribution of different collagen types and fibronectin in neurofibromatosis tumours.

Collagen types I, III, IV and V and fibronectin were localized in neurofibromas from six patients with von Recklinghausen's neurofibromatosis (NF) using indirect immunofluorescence (IIF) and peroxidase anti-peroxidase (PAP) techniques. Type I and III collagens were abundantly and rather evenly present in the tumours and formed a continuous network, but were absent from the capillary endothelial walls and were sparse in the perineurium of the occasional nerve fascicles. The type III/type I + type III collagen ratio in neurofibromas varied from 17.4% to 37.3% when estimated with cyanogen bromide peptide analysis. Fibronectin was detected in areas where type I and III collagens were present but was most intensively stained in the vascular walls and perineurium. Type IV collagen was detected at the dermo-epidermal junction of the skin overlying the tumours, in the endothelial cells of the capillaries, the perineurium and endoneurium. Furthermore, in the tumourous stroma there was plenty of type IV collagen appearing as a discontinuous patchy pattern suggesting abundant basement membrane material associated with cells forming the tumours. Type V collagen distribution was very similar to that of type IV collagen.

Collagen↗

PubMed1983

Age dependent repair of muscle rupture. A histological and microangiographical study in rats.

Healing of contusion injury in the gastrocnemius muscle was studied in young adult and old rats. A standard blunt muscle contusion was induced to the left calf of each animal and studied histologically and microangiographically 2-21 days after the injury. The inflammatory cell reaction was more intense, the haematoma was larger and the proliferation of fibroblasts and production of collagen scar more pronounced in the young rats. The sprouting of new capillaries and regeneration of ruptured muscle fibres occurred more rapidly and intensively in the young animals, and the resorption of haematoma and phagocytosis of necrotic tissue occurred later in the old rats. The decreased repairing capacity in muscles of older animals resembles that seen earlier in immobilized muscles of adult rats, indicating that the response to the stimulus of injury decreases with advancing age.

Aging↗