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Biomedical subjects

C Kuhn

Publications and source records attributed to C Kuhn.

At least 145 records · Page 8Linked to original sources
PubMed1986

Expression of glial filament protein (GFP) in nerve sheaths and non-neural cells re-examined using monoclonal antibodies, with special emphasis on the co-expression of GFP and cytokeratins in epithelial cells of human salivary gland and pleomorphic adenomas.

We describe two novel monoclonal antibodies specific for glial filament protein (GFP), i.e., GF12.23 and GF12.24 (both IgG2a]. These cross-react over a broad range of species with epitopes located in the alpha-helical rod domain typical of all intermediate filament (IF) proteins. These monoclonal antibodies were used, in conjunction with other monoclonal GFP antibodies, rabbit antiserum to GFP, and various antibodies to other cytoskeletal proteins, to examine the occurrence of GFP in cells outside of the central nervous system of rodents, cows, and humans. We detected some scattered GFP-containing cells in the neural sheaths in some species but not in others, and we obtained different results when comparing the rabbit antisera with the monoclonal GFP antibodies. In the enteric glia of rats, we observed GFP-positive cells with all of the antibodies used, whereas in human intestine, the various monoclonal antibodies showed no reaction with any intestinal cells. Similarly, no GFP was detected in surface cells of the lens of cows and rats using any of the GFP antibodies, whereas some reaction was seen in murine lens tissue. We were also unable to detect GFP-positive cells in human, bovine, or rat liver with any of the monoclonal antibodies, which is in contrast to the reactivity of the rabbit GFP antisera with some stellate perisinusoidal cells of rat but not bovine or human liver. The possible reasons for the discrepancies between the different species and the different antibody preparations used are discussed. In addition, using double-label immunofluorescence microscopy, we showed that normal human parotid glands contain a certain type of epithelial cell that co-expresses cytokeratins and desmosomal proteins with GFP. The histological distribution of these GFP-positive cells suggests that they represent a subset of the myoepithelial cells present in this tissue. Cells co-expressing cytokeratins and GFP - in some cases, apparently together with vimentin as the third IF protein present - were also identified in tumors derived from this salivary-gland epithelium, i.e., pleomorphic adenomas, in which GFP-positive cells were relatively frequent in the myxoid and chondroid components, thus confirming the work of other investigators. Possible implications for the concept of histogenesis of these tumor cells are discussed, as are possible mechanisms resulting in the co-expression of IF proteins.

Adenoma↗
PubMed1986

A monoclonal antibody to the carboxyterminal domain of procollagen type I visualizes collagen-synthesizing fibroblasts. Detection of an altered fibroblast phenotype in lungs of patients with pulmonary fibrosis.

Excessive collagen deposition plays a critical role in the development of fibrosis, and early or active fibrosis may be more susceptible to therapeutic intervention than later stages of scarring. However, at present there is no simple method for assessing the collagen-synthesizing and secreting activity of fibroblasts in human tissues. Type I procollagen carboxyterminal domains are proteolytically removed during collagen secretion. Thus, antibodies to these domains should stain fibroblasts synthesizing type I collagen but not extracellular collagen fibrils which could mask the signal from the cells. We developed and characterized a monoclonal antibody (Anti-pC) specific for the carboxyterminal propeptide of type I procollagen. To determine the relationship between Anti-pC staining and collagen synthesis, we stained embryonic and adult chicken tendon. Embryonic chick tendon fibroblasts actively synthesizing type I collagen stained heavily with Anti-pC, while quiescent adult tendon fibroblasts did not stain with Anti-pC. Wounded adult tendons developed fibroblasts that stained with Anti-pC at the wound site. Thus, Anti-pC specifically visualized fibroblasts actively synthesizing collagen. Lung biopsies from patients with fibrotic lung disease were stained with Anti-pC. Interstitial and intraalveolar fibroblasts in biopsies from patients with active fibrosis stained intensely with Anti-pC, while normal human lung was unstained. The absence of staining in normal lung supports the hypothesis that fibrosis is associated with an altered collagen-synthesizing phenotype of tissue fibroblasts. Anti-pC may provide a useful clinical tool for assessing fibrogenic activity at sites of tissue injury.

Antibodies, Monoclonal↗
PubMed1985

Comparative sequence analysis of duck and human hepatitis B virus genomes.

We have cloned and sequenced an infectious, functionally active genome of a duck hepatitis B virus (DHBV). It is 3,021 base pairs (bp) in length and shows little DNA sequence homology to the genome of human hepatitis B virus (HBV). However, the amino acid sequences of predicted viral gene products are similar between DHBV and HBV, and the genome organization present in DHBV reflects that of HBV. As in the mammalian virus the long minus strand of the DHBV genome encodes three long overlapping reading frames designated as P, S, and C. The fourth open reading frame, termed X, is absent in DHBV. A comparison with a sequence of a second DHBV isolate [Mandart et al, Journal of Virology 49:782-792, 1984] revealed a nucleotide sequence variation of 5.6% and confirmed the presented overall gene organization of DHBV.

Animals↗
PubMed1985

S-100 protein in normal, osteoarthrotic, and arthritic cartilage.

The occurrence of the S-100 protein was studied in normal and pathological cartilage from patients with osteoarthrosis and rheumatoid arthritis. In normal cartilage all cells of the different zones exhibit immunoreactivity for this protein. An identical distribution is observed in cases of osteoarthrosis and rheumatoid arthritis. Cellular pannus tissue usually is devoid of the S-100 protein. However, if chondroid metaplasia occurs in this tissue the cells become positive for the S-100 protein. From these results it is concluded that a chondroid metaplasia not only leads to a matrix comparable to cartilage but also contains cells that gain further characteristics of original chondrocytes.

Adult↗
PubMed1985

Ultrastructural distribution of fibronectin in normal and fibrotic human lung.

We studied the distribution of fibronectin in normal and fibrotic adult human lung and normal hamster lung using affinity-purified antifibronectin Fab'-horseradish peroxidase conjugates. In normal lung, fibronectin staining was present in alveolar capillary and epithelial basal lamina and associated with interstitial collagen fibers. In airway and larger vessels, fibronectin staining was associated with the basal lamina of smooth muscles. In contrast to the relative paucity of staining in normal lung, the alveolar basal lamina of fibrotic lung stained intensely for fibronectin. In addition, there was strong, periodic (approximately 600 A) staining of native collagen fibers for fibronectin. We conclude that fibronectin antigenicity is present in the alveolar epithelial and capillary endothelial basal lamina of normal human and hamster lung. The marked alterations in the apparent amounts and distribution of fibronectin in fibrotic human lung suggest its involvement in the cellular events accompanying human lung fibrosis.

Animals↗
PubMed1984

Transient change of organization of vimentin filaments during mitosis as demonstrated by a monoclonal antibody.

A monoclonal antibody specific for vimentin is described which, by immunofluorescence and immunoelectron microscopy, decorates fibrillar and/or granular structures in mitotic and early postmitotic cells but does not react with vimentin filaments of interphase stages of various cultured cells (rat vascular smooth muscle-derived cell line RVF-SM; SV40-transformed human fibroblasts; bovine kidney epithelial cells of line MDBK). These observations indicate that the organization of vimentin filaments varies during the cell cycle, undergoing a perimitotic change of filament organization. These changes of vimentin filaments are described in relation to those reported for cytokeratin filaments of various epithelial and carcinoma cells. The possible functional implications of filament protein rearrangements both during the cell cycle and in cell differentiation processes are discussed.

Animals↗
PubMed1984

Expression of hepatitis B antigens with a simian virus 40 vector.

Recombinant DNA molecules consisting of the simian virus 40 (SV40) early region and different subgenomic hepatitis B virus DNA fragments were constructed in vitro and packaged in vivo into SV40 capsids by using a complementing SV40 helper virus. Upon infection with these virus stocks the three known hepatitis B-specific antigens were expressed under SV40 control. The surface antigen was released into the medium, and the core antigen and its derivative hepatitis B e antigen were only detected intracellularly. Size analysis of the core gene product(s) by immunoblotting revealed the presence of a single protein species identical with the 21-kilodalton core antigen isolated from human liver. The hepatitis B core antigen expressing construct did not contain a putative precore sequence, indicating that such a sequence is not needed for hepatitis B core antigen synthesis in animal cells. S1 analysis demonstrated the use of SV40 signals for initiation and polyadenylation of the core gene transcripts. In addition, a processing-polyadenylation signal was identified within the core gene.

Cell Line↗
PubMed1984

Cloned duck hepatitis B virus DNA is infectious in Pekin ducks.

Approximately 10% of German-bred Pekin ducks were found to be chronically infected with duck hepatitis B virus (DHBV). The genomes of three German DHBV isolates analyzed were closely related but showed substantial restriction site polymorphism compared with U.S. isolates. We tested the infectivity of three sequence variants of cloned DHBV DNA by injecting them into the liver of virus-free ducklings. Most of these animals injected with double-stranded closed-circular or plasmid-integrated dimer DHBV DNA developed viremia, demonstrating the infectivity of all three cloned DHBV DNA variants. The cloned viruses produced were indistinguishable from those from naturally infected animals, implying that our experimental approach can be used to perform a functional analysis of the DHBV genome.

Animals↗
PubMed1984

Intrahepatic glucose: a requirement for neonatal ODC induction by specific hormones.

We have shown previously that short-term nutritional deprivation causes a tissue-specific loss of liver ornithine decarboxylase (ODC) induction after isoproterenol, phenylephrine, or glucagon administration in rat pups. To examine the role of nutrition in the regulation of hepatic ODC, we tested the ability of intragastric nutrient administration to reverse nutritionally related deficits in the ODC response to hormonal challenge. Intragastric whole milk was effective in restoring ODC induction and accumulation of its immediate product, putrescine, in response to isoproterenol administration. Glucose was shown to mediate this effect by the ability of intragastric skimmed milk, lactose, galactose, or D-glucose to return ODC induction, and the inability of casein, sucrose, fructose, L-glucose, or pyruvate plus lactate to do so. D-Glucose also reestablished ODC induction by phenylephrine and glucagon. Parenteral administration of D-glucose produced results comparable to those obtained after intragastric administration. Isoproterenol induction of ODC was prevented when hepatic glucose uptake was blocked by phlorizin but not by blockade of central nervous system glucose uptake with 2-deoxyglucose. We conclude that intrahepatic glucose is an absolute requirement for hepatic ODC induction by isoproterenol, phenylephrine, or glucagon in preweanling rats.

Animals↗
PubMed1984

Hemodynamic and metabolic responses to exercise after adrenoceptor blockade in humans.

The effects of acute alpha 1-adrenoceptor blockade with prazosin, beta 1-adrenoceptor blockade with atenolol, and nonselective beta-adrenoceptor blockade with propranolol were compared in a placebo-controlled crossover study of the hemodynamic and metabolic responses to acute exercise 2 h after prolonged prior exercise to induce skeletal muscle glycogen depletion, enhancing the dependence on hepatic glucose output and circulating free fatty acids (FFA). Plasma catecholamines were higher during exercise after, as opposed to before, glycogen depletion and were elevated further by all three drugs. Propranolol failed to produce a significant reduction in systolic blood pressure and elevated diastolic blood pressure. Atenolol reduced systolic blood pressure and did not change diastolic blood pressure. Both beta-blockers reduced FFA levels, but only propranolol lowered plasma glucose relative to placebo during exercise after glycogen depletion. In contrast, prazosin reduced systolic and diastolic blood pressures and resulted in elevated FFA and glucose levels. The results indicate important differences in the hemodynamic effects of beta 1-selective vs. nonselective beta-blockade during exercise after skeletal muscle glycogen depletion. Furthermore they confirm the importance of beta 2-mediated hepatic glucose production in maintaining plasma glucose levels during exercise. Acute alpha 1-blockade with prazosin induces reflex elevation of catecholamines, which in the absence of blockade of hepatic beta 2-receptors produces elevation of plasma glucose. The results suggest there is little role for alpha 1-mediated hepatic glucose production during exercise in humans.

Adrenergic alpha-Antagonists↗
PubMed1984

Receptor-mediated binding and internalization of colony-stimulating factor (CSF-1) by mouse peritoneal exudate macrophages.

Colony-stimulating factor (CSF-1) purified from L-cell-conditioned medium is a haemopoietic growth factor that specifically stimulates the proliferation and differentiation of mononuclear phagocytes. Using radioactively labelled CSF-1 [( 125I]CSF-1), the presence of specific CSF-1 receptor has been identified in the cells of the mononuclear phagocytic series and their precursors only. To determine the fate of [125I]CSF-1 bound to peritoneal exudate macrophages (PEM) at 37 degrees C, we have examined the distribution of radioactivity as a function of time by quantitative electron microscopic autoradiography. At 0 degrees C, we have localized the initial step in the binding of [125I]CSF-1 to the plasma membrane and its invaginations of the mouse PEM. Approximately 16% of the macrophages were not labelled at this time point. When the temperature was raised to 37 degrees C, the labelled CSF-1 was internalized progressively by the cells in a time-dependent fashion. The proportion of grains associated with the phagolysosome compartment increased progressively, reaching a plateau by 40 min after warming up, while the relative areas of the surface membrane and its invaginations decreased in invaginated membrane. At 37 degrees C, incubation with unlabelled CSF-1 resulted in a "down-regulation' of the subsequent [125I]CSF-1-binding activity by PEM in a time- and dose-dependent fashion. The restoration of CSF-1-binding activity after CSF-1 induced down-regulation was inhibited by cycloheximide, a potent protein synthesis inhibitor. These data provide direct evidence that at 37 degrees C, saturable binding of CSF-1 to PEM is followed by internalization and cellular degradation of the ligand and possibly its receptor by phagolysosomes.

Animals↗
PubMed1983

Neuroendocrine response to cold in Raynaud's syndrome.

Eleven patients with Raynaud's syndrome accompanied by monospecific IgG ANA, nine patients with Raynaud's syndrome in the absence of ANA, and nine normal volunteers were exposed to an ambient cold challenge during which time venous blood was continuously sampled. ANA negative patients were shown to have significantly higher levels of cortisol during a cold challenge than either ANA positive patients or normal controls, and exhibited significantly lower levels of plasma norepinephrine compared with normal controls. ANA positive patients did not differ significantly from normals in their neuroendocrine response to cold. It is suggested that the high plasma cortisol found in Raynaud's syndrome in the absence of ANA may be responsible for the vasospasticity in this group of patients.

Antibodies, Antinuclear↗
PubMed1983

Modulating role of lithium on dopamine turnover, prolactin release, and behavioral supersensitivity following haloperidol and reserpine.

The effects of haloperidol, reserpine, and concomitant lithium were evaluated in biochemical, endocrine, and behavioral studies in the rat. Concomitant administration of a chronic regimen of haloperidol and lithium did not prevent the development of tolerance as noted by dopamine metabolites in the striatum or olfactory tuberculum. Nor did chronic lithium alter behavioral response in rats treated with reserpine and challenged with the dopamine agonist apomorphine. Additionally, prolactin release was increased by haloperidol, but was not altered by acute or chronic lithium treatment. These findings are discussed in the light of present knowledge of pre- and postsynaptic receptor changes and the effects of lithium.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Immunocytochemical identification of epithelium-derived human tumors with antibodies to desmosomal plaque proteins.

Epithelial cells contain desmosomes, special intercellular junctions providing sites of membrane attachment for intermediate-sized filaments of the cytokeratin type (tonofilaments). Such sites of anchorage of tonofilaments appear as dense plaques on the cytoplasmic side of the desmosomal membrane. We have isolated desmosome-enriched fractions from bovine snout epidermis and tongue mucosa and have characterized the major protein associated with the desmosomal plaque. This protein occurs in equimolar amounts of two polypeptides of Mr 250,000 (desmoplakin I) and Mr 215,000 (desmoplakin II) which are chemically and immunologically related. Antibodies raised against desmoplakins allow the identification and localization of this protein in epithelial cells grown in tissues or in vitro and show crossreaction in species as diverse as man, mouse, and chicken. Using immunolocalization at the light and electron microscope levels, we show that these antibodies bind specifically to desmosomal plaques. Antibodies to desmoplakins have been used successfully for detection of desmosomal proteins in a broad variety of epithelium-derived human tumors, including primary carcinomas and their metastases, irrespective of the morphology of the specific tumor. Nonepithelial tumors examined have been negative. We propose to use antibodies to desmoplakins and to cytokeratins in pathological diagnosis as two independent markers for the positive immunocytochemical identification and classification of epithelium derived tumors.

Animals↗
PubMed1983

Differentiation of hemodynamic, humoral and metabolic responses to beta 1- and beta 2-adrenergic stimulation in man using atenolol and propranolol.

The respective contributions of beta-adrenoceptor subtypes to the hemodynamic, humoral and metabolic consequences of adrenergic stimulation during graded exercise in man were investigated using nonselective beta-adrenoceptor blockade with propranolol and beta 1-adrenoceptor blockade with atenolol. Doses of these agents that produced comparable suppression of beta 1 response as measured by antagonism of cardioacceleration during exercise were selected. Six healthy, nonsmoking males received these drugs in a placebo-controlled, Latin-square, randomized manner using a double-blind protocol. Both drugs produced comparable reductions of systolic blood pressure and elevation of diastolic blood pressure compared with placebo as exercise load increased. Propranolol produced higher peak epinephrine levels than atenolol or placebo (808 +/- 162, 640 +/- 190 and 584 +/- 153 pg/ml, respectively, p = 0.03), but norepinephrine levels did not show significant differences. Plasma renin activity was similarly suppressed both at rest and during all grades of exercise by both drugs. Lactate levels during moderate exercise were significantly lower after propranolol than after either atenolol or placebo (p = 0.03), but were similar at heavy work loads. Plasma glucose values rose on placebo (from 96.5 +/- 2.1 to 97.7 +/- 2.7 mg/dl) and on atenolol (from 99.7 +/- 2.2 to 102.1 +/- 4.8 mg/dl), but fell on propranolol (from 96.4 +/- 1.9 mg/dl to 87.2 +/- 2.5 mg/dl, p less than 0.01). These results indicate that blockade of vascular smooth muscle beta 2 receptors does not substantially alter hemodynamics during intense short-term exercise. Stimulation of renin release and lipolysis are produced through beta 1-adrenoceptor mechanisms, whereas beta 2 adrenoceptors are important in the provision of carbohydrate as an energy substrate for exercising muscle.

Adult↗