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Biomedical subjects

A C Johannessen

Publications and source records attributed to A C Johannessen.

At least 73 records · Page 4Linked to original sources
PubMed1987

Central venous pressure--a physiological stimulus for secretion of atrial natriuretic peptide in humans?

A sensitive radio-immunoassay (RIA) for the measurement of human alpha-atrial natriuretic peptide (ANP) in extracted plasma was developed and used in a study of the possible effect of posture on the concentration of ANP in plasma. The least detectable quantity was less than 2 pg per tube equivalent to 5 pg ml-1 plasma. In the middle sensitivity range (approximately 50 pg per tube), the within-assay and between-assay coefficients of variation were 4.0 and 2.8%, respectively. The recovery of ANP added to plasma prior to extraction was 95-101%. High pressure liquid chromatography (HPLC) of plasma extracts revealed that endogenous ANP was eluted in the same fractions as synthetic ANP. In order to investigate the effect of posture on the concentration of ANP in plasma six healthy volunteers were exposed to five positions in the following sequence: supine, standing, sitting, supine and 10 degrees head-down tilt on a tilt-table. The concentration of ANP was lower in the standing and sitting position than in the supine and head-down tilted position. In another study six healthy volunteers were subjected to passive tilting on a tilt-table in order to evaluate the effect of tilting on blood pressure (BP), heart rate, central venous pressure (CVP) and the concentration of ANP in plasma. It was found that a fall in CVP was accompanied by a significant decrease in the concentration of ANP and that a rise in CVP was accompanied by a rapid increase in the concentration of ANP in plasma. The results are in agreement with the hypothesis that CVP is a physiological stimulus for the secretion of ANP.

Atrial Natriuretic Factor↗
PubMed1987

Deposits of immunoglobulins, complement, and immune complexes in inflamed human gingiva.

Gingival biopsy specimens from 20 patients with moderate to advanced periodontitis were obtained from inflamed sites with pockets of 5 mm or more. Sections were studied by an immunofluorescence technique, using polyclonal rabbit or goat anti-IgG, anti-IgM, anti-C1q, anti-C3a, and anti-C3c and mouse monoclonal anti-C9. Prewashed ethanol-fixed and nonwashed ethanol-fixed or frozen specimens showed many plasma cells staining for IgG or C3a, suggesting the possible occurrence of a receptor for C3a in plasma cells. Plasma cells containing IgM were also seen. Deposits of IgG and IgM with C1q, C3a, and C3c, suggesting immune complexes, were demonstrated by a double staining technique, combining fluorescein (FITC) or rhodamine (TRITC)-labeled anti-immunoglobulins with TRITC- or FITC-conjugated antibody to C3a, C3c, and C1q. The complexes were located mainly within or around vessel walls. Deposits of C3a and C1q were found in vessel walls, in the basement membrane zone of oral gingival epithelium, or diffusely distributed in the tissues. Deposits of C3c were found to a lesser extent and only in vessel walls. Mouse monoclonal anti-C9, visualized with FITC-labeled rabbit anti-mouse and swine anti-rabbit antiserum, showed granular deposits of C9, mainly in the basement membrane zone of oral gingival epithelium. The study indicates the involvement of immune complex vasculitis in inflammatory periodontal lesions. Also, our observations of the occurrence of deposits of complement factors support the hypothesis that complement factors play an important role in the immunopathology of the periodontal lesion.

Antigen-Antibody Complex↗
PubMed1987

Effects of atrial natriuretic peptides and furosemide in conscious dogs.

Effects of ANF(8-33) and Auriculin A on renal variables were investigated in conscious water-diuretic dogs. The two substances were injected intravenously (1.08 micrograms/kg in 3 min) or ANF(8-33) was infused (0.2 microgram/kg X min in 20 min). The effects were compared to those of an equinatriuretic dose of furosemide (1.0 microgram/kg X min). Injections caused increases in sodium excretion, diuresis, and osmolar clearance. No significant change in exogenous creatine clearance (CCREA) occurred. Infusion of ANF(8-33) decreased blood pressure by 14% (P less than 0.01) and increased sodium excretion by a factor of 10 (P less than 0.01). The natriuresis was a function of increases in diuresis and urinary sodium concentration, the latter by a factor of 6 (P less than 0.01). Diuresis and free-water clearance (CH2O) increased by 60% (P less than 0.01), but urine osmolality did not change significantly. After the infusion a significant decrease in PAH clearance (CPAH) (P less than 0.01) was observed. Filtration fraction (FF) did not change. The furosemide natriuresis appeared later than that of ANF without significant deviations in diuresis, CH2O, CCREA, CPAH, and FF; urine osmolality increased by 35% (P less than 0.01). The effects of ANF(8-33) differ from those of furosemide in several ways. First, the onset of natriuresis is faster, second, the natriuresis is associated by marked increases in diuresis and free-water clearance but not in urine osmolality; and third, natriuresis is followed by a reduction in renal blood flow. The rapid natriuresis of ANF can occur without changes in glomerular filtration rate.

Animals↗
PubMed1987

Uraemic pericarditis, an epidemic disease?

Pericarditis (PC) is a frequent complication with renal failure. Numerous causes have been proposed. Over a six week period, we observed five cases of PC in five of 102 patients on maintenance haemodialysis. Viral cause was suspected in one case (Respiratory Syncytial Virus). During the past year, no recurrence of PC has been seen. The case clustering episodes might suggest a viral cause. The value of examining the patients by stetoscopy and echocardiography was documented.

Adult↗
PubMed1986

Effects of synthetic human atrial natriuretic peptide (hANP) in conscious dogs.

The effects of synthetic human atrial natriuretic peptide (hANP) on arterial blood pressure, heart rate, and renal functions were evaluated in conscious trained dogs in moderate sustained water diuresis. Synthetic hANP was given i.v. over 3 min at doses of 0.27-2.16 micrograms kg-1 body wt. It did not cause significant changes in blood pressure or heart rate. The rate of sodium excretion increased 20-fold following 2.16 micrograms kg-1 and 2.5-fold after 0.54 micrograms kg-1. Natriuresis was immediate and vanished after 10 min, regardless of dose. The concomitant increase in diuresis was less than 50%, but significant for a longer period of time. Increases in potassium excretion were significant, but small, that is, by a factor of 1.5-2.8. All natriuretic doses of hANP increased PAH clearance (at constant blood pressure), but some did so without measurably affecting creatinine clearance.

Animals↗
PubMed1986

In situ characterization of the inflammatory cell infiltrates of hyperplastic denture stomatitis.

Cryostat sections from 14 surgical specimens were examined to determine whether selected factors of the immune response related to histopathological reactions are present in the palatal mucosa affected by hyperplastic denture stomatitis. By means of various immunological techniques the presence of IgG, IgA, IgM, complement factor C3c, receptors for the Fc region of IgG (FcR) and for complement factor C3b (C3bR), T lymphocytes, and macrophages were studied. The inflammatory infiltrate was mainly located in the papillary part of the lamina propria. IgG, IgA, and IgM appeared both in plasma cells and intercellularly. FcR, C3bR, and T lymphocytes were present in the areas with inflammatory cell infiltrate. Macrophages were found in the papillary part of the lamina propria and within the epithelium. The immunological response in the mucosa affected by denture stomatitis was in many respects similar to that of marginal and apical periodontitis. We conclude that hyperplastic denture stomatitis is a complex inflammatory lesion showing elements of both humoral and cellular immune responses.

Antibody Formation↗
PubMed1984

In situ characterization of mononuclear cells in human dental periapical inflammatory lesions using monoclonal antibodies.

Mononuclear cells in cryostat sections of human dental periapical inflammatory lesions were studied with the aid of murine monoclonal antibodies and with indirect immunofluorescence microscopy. T lymphocytes (OKT3-positive cells) made up a major part of the cells in the infiltrates. They were found mainly in clusters, although single cells were also seen. T helper cells (OKT4) were more numerous than suppressor/cytotoxic T cells (OKT8-positive cells), with a ratio of approximately 2:1. Langerhans cells (OKT6-positive cells) were not demonstrated: only a few scattered HNK 1-positive cells, probably natural killer cells, were detected. A large number of OKM1- and OKIa 1-positive cells were detected in the infiltrates. Their size and number varied considerably in the different areas of the sections. These cells are probably macrophages. Sheets of small OKIa 1-positive cells were also demonstrated, indicating the presence of B lymphocytes or activated T lymphocytes. The results indicate that immune reactions may be of importance in the pathogenesis of periapical inflammatory lesions.

Antibodies, Monoclonal↗
PubMed1984

In situ characterization of cell infiltrates in human dental periapical granulomas. 2. Demonstration of receptors for the complement components C3b and C3d.

The inflammatory cell infiltrates in human dental periapical granulomas were studied through the demonstration of receptors (R) for fragments C3b and C3d of the complement component C3, C3bR and C3dR were detected in cryostat sections by the closed chamber hemadsorption technique. Sheep erythrocytes sensitized with rabbit IgM antibody and coated with human C3B or C3d were used as indicator cells. Of the 62 granulomas studied, 23 showed strong or moderate C3bR activity, and weak C3dR activity was detected in 5 out of 25 specimens. The C3bR activity was abolished by treatment with 0.25 mM periodic acid, indicating that carbohydrate is a part of the C3bR. Using an antiserum to C3R as first layer in indirect immunofluorescence experiments, the C3R was localized to cell membranes. The low C3dR activity indicates that a minor part of the mononuclear cells in the human periapical granulomas were B lymphocytes.

Adult↗
PubMed1984

In situ characterization of cell infiltrates in human dental periapical granulomas. 3. Demonstration of T lymphocytes.

Cryostat sections of 66 snap-frozen dental periapical granulomas were examined for T lymphocytes by the closed chamber hemadsorption technique using sheep erythrocytes (E) treated with 2-aminoethylisothiouronium bromide hydrobromide (AET) as indicator cells (AET-E). T lymphocytes were also demonstrated by immunofluorescent staining using a rabbit anti-T lymphocyte antiserum. Eighty-six % of the granulomas showed adherence of AET-E, and often a focal AET-E adherence pattern was seen, indicating a localized infiltration of T lymphocytes. Diffuse, moderate binding of AET-E to sections of some granulomas may be due to recirculating T lymphocytes traversing the tissue. The results of the immunofluorescence test parallelled the results obtained in the hemadsorption test. The results show that mononuclear cell infiltrates of periapical dental granulomas usually contain T lymphocytes. Although their pathogenetic function in dental periapical granulomas is still not known, infiltrates of T lymphocytes indicate that cellular immune reactions are involved.

Adult↗