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Biomedical subjects

D Drenckhahn

Publications and source records attributed to D Drenckhahn.

156 records · Page 9Linked to original sources
PubMed1977

Immunofluorescence-microscopic demonstration of myosin and actin in salivary glands and exocrine pancreas of the rat.

Actin and myosin were localized in various salivary glands (parotid, submandibular, sublingual, lingual and Harderian gland) and the exocrine pancrease of rats by indirect immunofluorescence microscopy using specific rabbit antibodies against chicken gizzard myosin and actin. A bright immunofluorescent staining with both antibodies were observed at three main sites: (1) In myoepithelial cells of all salivary glands, (2) in secretory gland cells underneath the cell membrane bordering the acinar lumen (except Harderian and mucous lingual gland), and (3) in epithelial cells of the various secretory ducts (of all glands) in similar distribution as in acinar cells. The present immunohistochemical findings in acinar cells could lend further support to a concept suggesting that myosin and actin are involved in the process of transport and exocytosis of secretory granules.

Actins↗
PubMed1977

Localization of myosin and actin in ocular nonmuscle cells. Immunofluorescence-microscopic, biochemical, and electron-microscopic studies.

Myosin and actin were localized by indirect immunofluorescence microscopy using specific antibodies prepared in rabbits against highly purified gizzard myosin and actin. A strong fluorescence staining with both antibodies was observed in rat corneal epithelial cells, anterior lens epithelial cells, rod inner segments, and in rat and frog pigment epithelial cells. The immunohistochemical localization of myosin in corneal epithelial cells was further supported by the electrophoretic and immunological identification of smooth muscle type myosin heavy chain in pure corneal epithelial abrasions. Electron-microscopic observations revealed a clear correlation between staining with actin antibodies and the presence of numerous thin cytoplasmic filaments (50-80 A in diameter). The functional and biochemical nature of 90-110 A filaments occurring in corneal and lens epithelial cells, as well as the ultrastructural localization of myosin in ocular nonmuscle cells under study remains obscure.

Actins↗
PubMed1977

Axonal and cellular alterations in the inner ear of rats treated with chlorphentermine or iprindole.

An electron-microscopic study was carried out on the inner ear of rats, which had been treated with the anorectic drug chlorphentermine and the antidepressant drug iprindole, two cationic amphiphilic compounds known to induce a generalized lipidosis. After chronic drug treatment the following vestibular and cochlear alterations were observed: a) numerous lamellated and crystalloid cytoplasmic inclusion bodies in various cell types, typical of drug-induced lipidosis; b) axonal balloonings predominantly affecting preterminal sensory endings which were filled with masses of coarse osmiophilic inclusions and autophagic vacuoles. With prolonged treatment degeneration of nerve fibers below the sensory epithelium was observed in increased numbers. Axonal changes are tentatively interpreted to result from drug-induced interference with certain catabolic processes involved in the normal degradation of axoplasmic constituents.

Animals↗
PubMed1976

Alterations in peripheral nerves of rats treated with chlorphentermine or with iprindole.

This study deals with the effects of two amphiphilic lipidosis-inducing drugs (chlorphentermine, iprindole) upon the ultrastructure of peripheral nerves of rats. After prolonged drug treatment the preterminal and terminal axoplasm of motor and sensory nerves within skeletal muscles contain numerous abnormal inclusions (osmiophilic conglomerates, autophagic vacuoles, lamellated bodies). By contrast, the axons within large peripheral nerves are little effected. The present observations are tentatively interpreted as resulting from interference with catabolic processes involved in the normal turnover of axoplasmic constituents at the nerve terminal. The exact pathogenesis and the functional significance of these alterations remain to be elucidated.

Animals↗
PubMed1976

Myopathy in rats treated with chlorphentermine or iprindole.

Muscular lesions were induced in rats by prolonged administration of chlorphentermine and iprindole. The alterations consisted of longitudinal fibre splitting, fibre degeneration and necrosis, and of formation of dense cytoplasmic inclusions and large cytoplasmic vacuoles. The soleus muscle was more severely affected than were extensor digitorum longus (EDL), gastrocnemius, and lumbrical muscles. This myopathy closely resembles that induced by chloroquine. The pathogenesis of the muscular lesions, and causal relationship between myotoxic and lipidosis-inducing effects of the drugs under study remain to be elucidated.

Animals↗
PubMed1976

Lysosomal alterations in cultured macrophages exposed to anorexigenic and psychotropic drugs.

Cultured rat macrophages were used for an in vitro study of drug-induced lipidosis. Cells were exposed for 24 hours to equimolar concentrations (5 X 10(-5) and 1 X 10(-4) M) of the following amphiphilic (amphipathic) cationic drugs: chlorphentermine, amitriptyline, 1-chloro-amitriptyline, iprindole, noxiptiline, chlorpromazine. In addition the less amphiphilic drug phentermine was used. Ultrastructurally, the cytologic changes essentially consisted of formation of multilamellated cytoplasmic inclusions, which possessed acid phosphatase activity. The abnormal inclusions are interpreted to result from intralysosomal accumulation of polar lipids. Under the present in vitro conditions all drugs except phentermine, had similar potencies to induce such lysosomal alterations, quite in contrast to the great quantitative differences previously observed under in vivo conditions. The present results lend further support to a concept that regards a pronounced amphiphilic (amphipathic) character to be responsible for the lipidosis-inducing action of various cationic compounds. Cultured macrophages are suggested as a useful tool to investigate this structure-activity relationship, which under in vivo conditions may be obscured by superimposed parameters such as drug metabolism.

Acid Phosphatase↗
PubMedDate not supplied

Induction of human vascular endothelial stress fibres by fluid shear stress.

Endothelial cells of the arterial vascular system and the heart contain straight actin filament bundles, of which there are few, if any, in the venous endothelium. Since stress fibre-containing endothelial cells within the vascular system tend to be located at sites exposed to particularly high shear stress of blood flow, we have investigated, in an experimental rheological system (Fig. 1), the response of the endothelial actin filament skeleton to controlled levels of fluid shear stress. Here we report that endothelial stress fibres can be induced by a 3-h exposure of confluent monolayer cultures of human vascular endothelium to a fluid shear stress of 2 dynes cm-2, approximately the stress occurring in human arteries in vivo. Fourfold lower levels of shear stress that normally occur only in veins, had no significant effect on the endothelial actin filament system. The formation of endothelial stress fibres in response to critical levels of fluid shear stress is probably a functionally important mechanism that protects the endothelium from hydrodynamic injury and detachment.

Actinin↗
PubMedDate not supplied

Cytoskeleton and epithelial polarity.

The membrane surface of polarized epithelial cells can be divided in apical and basolateral domains that differ in molecular composition and function. Components of the cytoskeleton are involved in critical steps of both generation and maintenance of cell polarity. Generation of polarity is controlled by microtubules that serve as uniformly aligned and polarized cytoplasmic guiding structures for the vectorial and selective transport of Golgi-derived carrier vesicles to the apical cell surface. Targeting of membrane proteins to the basolateral cell surface does not depend on microtubules but follows the constitutive bulk flow of membranes. Once inserted into the lipid bilayer several membrane proteins such as the kidney anion exchanger 1 (AE1) and the sodium pump become immobilized at specialized microdomains of the lateral cell surface. Evidence is provided that both membrane proteins are linked via ankyrin to the spectrin-based membrane cytoskeleton that underlies the basolateral membrane domain. Linkage of these and other integral membrane proteins to the cytoskeleton may not only place them to specialized sites of the plasma membrane but may also prevent these transporters from clustering and endocytosis, thus helping them to stay at the cell surface. In search of sequence motifs involved in binding of integral membrane proteins to components of the cytoskeleton we found that the binding interface of AE1 to protein 4.1 (an actin and spectrin cross-linking protein) consists of a cluster of five amino acid residues, namely IRRRY in AE1 and LEEDY on protein 4.1. This motif may play a more general role in cytoskeleton membrane linkages.

Amino Acid Sequence↗