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Biomedical subjects

A Larsson

Publications and source records attributed to A Larsson.

At least 343 records · Page 19Linked to original sources
PubMed1989

Binding of complement component C5 to model immune complexes and the use of anti-C5 antibodies for determination of C5-containing circulating immune complexes.

When normal human or mouse serum is added to micro ELISA plates coated with monomeric or aggregated IgG, complement component C5 binds to IgG. C5 binding was demonstrated with a specific chicken anti-C5 antibody. Hydrazine treatment of the serum or addition of EDTA to the serum abolished the binding of C5. C5-deficient mouse serum was negative for C5 binding, whereas the same serum supplemented with human C5 restored the binding of C5. Chicken anti-C5-coated plates were used for determination of C5-containing circulating immune complexes (CIC). Increased concentrations of CIC were found in sera from patients with rheumatoid arthritis and Bell's palsy.

Antigen-Antibody Complex↗
PubMed1988

Radical formation in the dimeric small subunit of ribonucleotide reductase requires only one tyrosine 122.

The small subunit of ribonucleoside-diphosphate reductase (EC 1.17.4.1) is a homodimer. Its catalytic site contains one tyrosyl radical, which is localized to Tyr-122 in one of its polypeptide chains. The engineered Tyr-122----Phe protein was used to demonstrate that it is possible to form a correct ferric iron center in vitro in the absence of Tyr-122. Heterodimers, consisting of one Tyr-122-containing polypeptide chain and one Phe-122-containing polypeptide chain, were constructed. The heterodimer population contained one-half the amount of tyrosyl radical as compared to a homodimer with Tyr-122, i.e. every second heterodimer contains a tyrosyl radical. Thus, one Tyr-122 is sufficient for radical formation. Radical-containing heterodimers are catalytically competent.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Determination of circulating immune complexes by chicken anti-human C3 and anti-human C1q microELISA.

The present study reports on an anti-human C1q and an anti-human C3 microELISA for measuring circulating immune complexes (CIC). Affinity-purified chicken anti-human C3 and anti-human C1q were used as capture antibodies and protein A-alkaline phosphatase conjugate for detection. Chicken antibodies do not activate mammalian complement, do not react with rheumatoid factor and are not bound to anti-mammalian IgG antibodies or protein A, which often are used for detection in ELISA. They are therefore suitable as capture antibodies in CIC assays. We have tested Bell's palsy patients and found an increase in both anti-C3- and anti-C1q-containing CIC in acute and convalescent sera compared with the normal.

Animals↗
PubMed1988

Chicken antibodies: a tool to avoid false positive results by rheumatoid factor in latex fixation tests.

19 rheumatoid factor (RF)-positive sera (Waaler-Rose test) and ten control sera were tested in latex agglutination. All RF-positive sera agglutinated latex particles coated with the different mammalian IgGs (cow, horse, human, mouse, sheep and rabbit) and with chicken anti-human C3 (which was used as a positive control), but none of them with non-specific chicken IgG. The control sera were all negative except when tested with chicken anti-human C3. Chicken antibodies should therefore be useful in assays were RF could interfere and give false positive reactions (e.g., nephelometry, latex agglutination or ELISA).

Animals↗
PubMed1988

Sensory innervation of the ear drum and middle-ear mucosa: retrograde tracing and immunocytochemistry.

The distribution and origin of nerve fibers of presumed sensory nature in the ear drum and middle-ear mucosa of the rat were studied by a retrograde tracing technique in combination with immunocytochemistry. Application of True Blue (TB) on the ear drum or on the middle-ear mucosa labeled nerve cell bodies in the jugular, trigeminal, geniculate and cervical dorsal root ganglia (C2-C4). Judging from the number of TB-labeled nerve cell bodies the jugular and trigeminal ganglia contributed the major component to the sensory innervation of the ear drum and the middle-ear mucosa, while the contribution from the geniculate and cervical dorsal root ganglia was relatively minor. The majority of the TB-labeled nerve cell bodies contained calcitonin gene-related peptide (CGRP), whereas minor populations stored substance P (SP) and neurokinin A (NKA). Nerve fibers containing SP, NKA and CGRP were moderate in number in the middle-ear mucosa and few in the ear drum. Double immunostaining revealed that SP invariably coexisted with NKA in nerve cell bodies in the ganglia examined. The SP/NKA-containing nerve cell bodies constituted a subpopulation of those storing CGRP. The findings indicate that several ganglia project to the ear drum and middle-ear mucosa and that many neuropeptides are involved in the mediation of middle-ear sensitivity.

Afferent Pathways↗
PubMed1988

Xanthomatous lesions of the mandible: osseous expression of non-X histiocytosis and benign fibrous histiocytoma.

Seven cases of xanthomatous lesions of the mandible, followed from 1 to 18 years, are documented. All lesions were benign and painless; radiographic appearances varied from single and well-demarcated to diffuse and multilocular. Microscopic examination showed sheets of histiocytes with xanthoma or foam cells, fibroblasts and fibrous tissue, and inflammatory cells as well as cells in transition, with characteristics of both histiocytes and fibroblasts. Immunohistochemical staining and electron microscopic observation provided further evidence of the biphasic nature of this cell population. Twelve similar cases were found in the literature under a variety of diagnostic or descriptive labels. Our findings show that these lesions are histiocytic in nature and that they range from small, innocuous lesions, which we regard as the osseous counterpart of non-X histiocytosis, to larger, more destructive lesions diagnosed as benign fibrous histiocytoma (fibrous xanthoma) of bone.

Adolescent↗
PubMed1988

Sublethal effects of tetrachloro-1,2-benzoquinone--a component in bleachery effluents from pulp mills--on vertebral quality and physiological parameters in fourhorn sculpin.

The effects of tetrachloro-1,2-benzoquinone (TCQ), a component in bleached kraft mill effluents (BKME), on vertebral and physiological parameters were investigated in juvenile fourhorn sculpin, Myoxocephalus quadricornis L. After about 4.5 months of exposure to 0.1 and 0.5 mg TCQ/liter in 7% salinity brackish water, the fish demonstrated vertebral deformities, aberrant mechanical properties of the vertebrae, effects on white and red blood cell counts, enhanced activity of delta-aminolevulinic acid dehydratase in erythrocytes, and increased levels of ascorbic acid in the liver. The effects are discussed in relation to those previously observed in fish exposed to complex BKME in the field and the laboratory.

Animals↗
PubMed1988

Long-term effects of bleached kraft mill effluents on red and white blood cell status, ion balance, and vertebral structure in fish.

In a laboratory investigation fourhorn sculpin (Myoxocephalus quadricornis) were exposed for 5-9 months to wastewater from pine and birch lines from a bleached kraft pulp plant. This long-term exposure to bleached kraft mill effluent (BKME) affected the hematology, the ion balance, and the vertebral structure. Decreased values for hematocrit and hemoglobin and a reduced red blood cell count, as well as increased levels of methemoglobin, indicated disturbances in the red blood cell status. The white blood cell picture was not significantly affected by the BKME exposure. Decreased levels of potassium and chloride ions in the blood plasma in some of the exposed fish suggest an impaired ability to maintain ion homeostasis. Elevated frequencies of vertebral deformations in fish exposed to BKME confirm previous observations of vertebral damage in feral fourhorn sculpin caught in the receiving body of water of the same bleached kraft pulp industry. Many of the parameters analyzed in this investigation may be used as health indicators in future laboratory and field studies on fish exposed to BKME.

Animals↗
PubMed1988

Assessment of polyclonal antibody binding of ligand by Sips' equation or by the exact polyclonal equation. Comparison of models.

Different possibilities of modelling equilibrium data on polyclonal antibody binding of ligand were investigated. The binding curves of the exact polyclonal model, based upon the mass-action law, and the Sips' model were compared. The basic assumption was that the free energy of binding is distributed according to the Gauss normal distribution. Using a few equations, the values of binding site concns and affinity constants of the individual clones were converted to the parameters of Sips' equation (that is, A = Ab binding site concn, K0 = average affinity, Hi = heterogeneity index). It was demonstrated that the binding curves from the exact polyclonal and the Sips' equations were very similar for simulated, approximately normally distributed antibody populations. Even when only two or three Ab-clones are involved, the Sips' and the exact polyclonal binding curves are very similar as long as the ratio between affinity constants does not exceed 10. Equilibrium data plotted as bound ligand concn on a linear scale vs free ligand concn on a logarithmic scale (or alternatively after logarithmic transformation of free ligand concn) form the well known sigmoid saturation curve. A mathematical relationship was demonstrated between half-height slope of such curves, resulting from approximately normally distributed antibody populations, and parameters of Sips' equation. The half-height slope is Hi X A/4 when natural logarithms are used. The ideas described were illustrated by weighted nonlinear curve-fittings applied to actual equilibrium data on anti-DNP antibodies. Tested in this way, the Sips' and a 2-clonal model gave equally good fit but somewhat different average affinities. It was concluded that it is often impossible to distinguish between a 2-clonal, a 3-clonal or an approximately normally distributed antibody population by curve-fitting to experimental equilibrium data.

2,4-Dinitrophenol↗
PubMed1988

The activation peptide of pancreatic procolipase decreases food intake in rats.

Pancreatic procolipase is a cofactor for lipase and necessary for optimal fat digestion in the intestine during a meal. It is activated by trypsin in the intestine during release of an activation peptide, with the sequence Val-Pro-Asp-Pro-Arg in rat. This peptide, in the following termed VPDPR, was found to decrease food intake in rats. The human procolipase activation peptide with the sequence Ala-Pro-Gly-Pro-Arg (APGPR) had no effect on food intake in rats, nor the trypsinogen activation peptide with the sequence Phe-Pro-Val-Asp-Asp-Asp-Asp-Lys (FPVDDDDK). Procolipase added to standard pellets decreased the daily food intake in rats, whereas colipase added to pellets had no effect.

Animals↗
PubMed1988

A possible physiological function of pancreatic pro-colipase activation peptide in appetite regulation.

Pancreatic pro-colipase activation peptide, a pentapeptide with the sequence VPDPR was found to significantly suppress food intake of 20 h fasted Sprague-Dawley rats in a dose-dependent way. A rat treated with pro-colipase-enriched pellets for 26 days showed decreased daily food intake and retarded growth, which were restored during a following period of regular feeding. Genetically obese Zucker rats (fa/fa) were found to contain a reduced content of pancreatic pro-colipase (60% reduction), whereas the pancreatic lipase content was normal. A physiological function of pancreatic pro-colipase activation peptide as an endogenous satiety signal is suggested.

Animals↗
PubMed1988

Clinical and immunological features of Sjögren's syndrome in patients with primary biliary cirrhosis with emphasis on focal sialadenitis.

Serological and pathological findings in 21 patients with primary Sjögren's syndrome (primary SS) were compared with those in 32 patients with primary biliary cirrhosis (PBC). In ELISA, anti-SS-B/La antibodies were detected in sera from 14 (67%) of the patients with primary SS, but only from 12 (38%) of those with PBC. With the Ouchterlony test, anti-SS-A/Ro antibodies were found in sera from 15 (71%) of the primary SS patients, but in no PBC patient. Of those PBC patients investigated prospectively with objective tests, four of 11 (36%) had keratoconjunctivitis sicca, and five of 15 (33%) had pathological sialometry results. In contrast, all PBC patients but one (i.e., 14 of 15 or 93%) showed evidence of focal sialadenitis. In immunochemical study of PBC patients, IgM immunoreactivity was found in the stroma, particularly adjacent to excretory ducts and acini in salivary glands (5 of 5), whereas no such IgM deposits were observed in patients with primary SS (3 of 3), nor in healthy controls (n = 20). We conclude that the frequency of anti-SS-A/Ro and anti-SS-B/La antibodies in serum is lower in PBC patients than in patients with primary SS. The incidence of focal sialadenitis is high in PBC, though only one third of the PBC patients studied here showed clinical evidence of glandular dysfunction. With immunochemical techniques, sialadenitis associated with PBC is distinguishable by its significant IgM reaction from sialadenitis in primary SS.

Aged↗
PubMed1988

Monoclonal antibodies against leucoagglutinin-reactive human T-lymphocyte surface components. II. Studies on the mechanism of K46M-induced activation and determination of the frequency of responding cells.

A monoclonal antibody, K46M (IgM kappa), obtained after immunization with leucoagglutinin (La)-reactive T-cell surface components, stimulated human lymphocytes to proliferate. It induced maximal proliferation at greater than 20 micrograms IgM/ml after 3-4 days of culture. Cells stimulated by K46M produced interleukin 2 (IL-2) and gamma interferon (IFN-gamma) and expressed receptors for IL-2 and transferrin. The majority of the activated cells were phenotypically T cells as defined by monoclonal antibodies against CD3 and CD2, and an increase in the K46M-positive cells was also observed during the activation period. K46M-activated cells display major histocompatibility complex (MHC)-unrestricted cytotoxicity against several cultured target cells. The frequencies of the cytotoxic and of the proliferative precursor cells were determined using a limiting dilution assay. K46M seems to activate a larger fraction of cytotoxic precursor cells against Molt 4 than against K562, but the statistical significance of these observations requires further exploration. Both K46M or La activated 40% of PBL to proliferate, whereas 70% of PBL were induced by OKT3. However, the frequency of K46M-activated cells was 40% only when the lymphocytes were plated at low cell densities, i.e. less than 0.5 cells per well. At higher densities an inhibition of proliferation was seen that resulted in a biphasic response curve, indicating that the activation of PBL by K46M was not a single hit event. This was not found with either La or OKT3. Whether K46M, in contrast to OKT3 and La, activates a subpopulation with suppressor activity remains to be established.

Animals↗
PubMed1988

Immunization with nanogram quantities of nitrocellulose-bound antigen, electroblotted from sodium dodecyl sulphate-polyacrylamide gels.

Intrasplenic immunization with antigen immobilized on nitrocellulose (NC) paper results in an immune response with nanogram amounts of antigen without the use of Freund's adjuvant. Comparing the sensitivity of the intrasplenic immunization with intraperitoneal or subcutaneous administration, we found that the intrasplenic method resulted in more positive animals with higher titres than did the other techniques with the smallest amount of antigen (70 ng of bovine serum albumin). With larger amounts of albumin the intraperitoneal method yielded the highest titres. No loss of antigenicity was observed when we immunized with equal amounts of protein separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotted and stained with either Coomassie brilliant blue R 250 or Amido black 10 B.

Animals↗
PubMed1988

Enhancement of human spontaneous cell-mediated cytotoxicity by a monoclonal antibody against the large sialoglycoprotein (CD 43) on peripheral blood lymphocytes.

A murine monoclonal antibody, MoAb B1B6 (IgG1 chi), which recognizes the large sialoglycoprotein (LSGP) on human peripheral blood lymphocytes (PBL) effectively enhanced the spontaneous cytotoxicity of these cells against the natural killer (NK)-sensitive target cells K562 and Molt-4. Whereas preincubation of the lymphocytes with MoAb B1B6 resulted in increased cytotoxicity, preincubation of the target cells had no effect, indicating that the MoAb amplified cytotoxicity at the effector cell level. Kinetic analysis of the data revealed no differences between the control and the MoAb-treated lymphocytes with regard to Vmax, usually considered to reflect the overall lytic potential of the cells. The slopes of the saturation curves, however, differed significantly for the two cell populations, indicating a substantial increment in the activity of the MoAb-treated cells. When studied at the single cell level and with K562 as targets, treatment of PBL with the MoAb resulted in the recruitment of new effector lymphocytes from the pool of non-binding cells. In contrast, when Molt-4 cells were employed as targets, no additional effector cells were recruited. These results indicate that the enhanced cytotoxicity induced by MoAb B1B6 is the result of either recruitment of new effector lymphocytes or of an increased recycling capacity of preexisting effector cells. Together with previous observations, these findings support the conclusion that LSGP belongs to the set of surface molecules which regulate human lymphocyte activation.

Antibodies, Monoclonal↗