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Biomedical subjects

K Wake

Publications and source records attributed to K Wake.

14 recordsLinked to original sources
PubMed1978

The outer segments of photoreceptive pinealocytes in the pineal organ of the funa, Carassius gibelio langsdorfi. A scanning electron microscopic study.

The form and size of the outer segments of photoreceptive pinealocytes in the pineal organ of the funa, Carassius gibelio langsdorfi, were observed with the scanning electron microscope. The height of the outer segments measures between 1 and 3 micrometer and the diameter varies widely from 1.5 to 8 micrometer. Various forms of outer segments, i.e. a slender type, a dome-like type, a cap-like type and a helical type, were demonstrated. The parallel-oriented filamentous processes of the inner segments have the same length as the outer segments and a diameter of approximately 100 nm; they are projections from the apical border of the inner segment and surround the cone-like outer segments. The processes make a right angle with the lamellar disks. The distance between two processes averages 100 nm. The lamellar disks of the outer segments are oriented at right angles to the modified cilium in the basal part, but the angle often changes in the peripheral part, where the lamellar disks are raised and become parallel to the cilium.

Animals↗
PubMed1977

Photoreceptor-like outer segments in the pineal organ of the lovebird, Uroloncha domestica (Aves: passeriformes). A scanning electron microscopic study.

In the pineal organ of the lovebird, Uroloncha domestica, bulbous, cup-shaped and elongated outer segments of photoreceptor-like pinealocytes are demonstrated by scanning electron microscopy. These scarce outer segments, 4-11 micron in length, extend into the pineal lumen. The present structural observations speak in favor of photosensitive pinealocytes in the pineal organ of Uroloncha domestica. The relation of the photoreceptor-like pinealocytes to acetylcholinesterase-positive nerve cells and a nervous connection between the pineal and the brain indicate that the pineal organ of this passeriform species may be the site of neuroendocrine and photoreceptive functions.

Acetylcholinesterase↗
PubMed1977

The pinealocyte--a paraneuron? A review.

The pineal complex develops from a tubular evagination of the diencephalic roof. In amphibians a proliferation zone is the source of the pinealocytes and of the cells of the subcommissural organ. The pinealocytes are not real nerve cells, but derived likewise from the embryonic neural epithelium. The pinealocytes of lower vertebrates are directly photosensitive; however, the morphological structures for direct light perception are gradually lost in the phylogenetic development and are absent in the pinealocytes of mammals. A secretory function is shown in the pinealocytes of all vertebrates, but it is more pronounced in the pinealocytes of reptiles, birds and mammals; dense-cored vesicles originate in the Golgi complex and are transported to and accumulated in the terminals of the basal processes near the perivascular space. Nerve cells are in synaptic ribbon contact with pinealocytes in lower vertebrates and their axons give a rise to the tractus pinealis. The nerve cells and nervous connection with the brain are absent in the pineal organ of mammals. Only few autonomic fibers reach the pineal organ of lower vertebrates, but the sympathetic and parasympathetic innervation are well developed in the pineal organ of most species of birds and mammals. The transmitter release from the sympathetic fibers is influenced by environmental light; light mediates in this way the activity of hormone producing enzymes in the pinealocytes. The synthesis of indolderivates, like melatonin, is confirmed and the presence of a polypeptide hormone is discussed. Accordingly, the pineal organ functions as a "neuro" chemical, "neuro" endocrine transducer or photo-"neuro" endocrine organ, which converts a light input (direct in lower vertebrates, via transmitter release by sympathetic fibers in mammals) into a hormonal output. The pineal organ thus provides the animal with a "biological clock", which is geared to the lighting environment. The pineal organ is a regulator (or a regulator of regulators) for several body functions. In mammals, the influence on the synchronization of the gonadal activity is best known. The pinealocyte is a hormone producing cell, which shows common features with the liquor contacting neurons and with the neurosecretory cells; after the definition of FUJITA (1976) the pinealocyte is said to be a paraneuron, also.

Animals↗
PubMed1976

Formation of myoneural and myotendinous junctions in the chick embryo. Role of acetylcholinesterase-rich granules in the developing muscle fibers.

The mode of formation of the myoneural and myotendinous junctions was investigated in the thigh muscles of the chick embryo. Myotendinous junctions first appeared on day 11 of incubation, whereas myoneural junctions developed on day 12. Intracellular AChE activity in the muscles increased by the 12th day of incubation, and decreased rapidly after the formation of the myoneural junctions. Light and electron microscopically, AChE activity was demonstrated in the nuclear envelope, sarcoplasmic reticulum, Golgi complex, and in large granules which appeared to be derived from the Golgi complex. Large granules showing an intense AChE activity accumulated in the sarcoplasm at the poles of the muscle fiber before the formation of myotendinous junctions. After the translocation of this intracellular enzyme onto the sarcolemma, most likely the result of an exocytosis of the granules, the myotendinous junctions were formed. The AChE-rich granules present in the middle of myotubes developed into spindle- or comma-shaped cisternae which were located in the sarcoplasm just below the presumptive motor endplates. The present results suggest that the transport of AChE-rich granules to the sarcolamma is the first step in the formation of myoneural and myotendinous junctions.

Acetylcholinesterase↗
PubMed1976

Inhibition of adjuvant arthritis by histamine.

Histamine was injected subcutaneously to rats at doses of 2--10 mg/kg, twice daily for various periods after an intradermal adjuvant injection into one hind paw. The administration of histamine prevented the appearance of the secondary lesion in the noninjected paw, but did not affect the primary swelling of the injected paw or the established secondary lesion. The histamine effect was dose-dependent with the most effective time of administration being from the 5th to the 10th day after adjuvant injection. Arthritic lesions found in control animals in histological and roentgenographic examinations were also inhibited in histamine-treated animals. Sinomenine, a histamine releaser, likewise showed a suppressive effect on the secondary lesion. Burimamide, a histamine H2-receptor antagonist, blocked these histamine effects, while mepyramine, a H1-receptor antagonist, did not have such a blocking effect. The findings suggest that histamine may inhibit the development of adjuvant arthritis by an immunosuppressive mechanism mediated through activation of H2-receptors on lymphoid cells.

Adjuvants, Immunologic↗
PubMed1976

Occupational health hazards resulting from elevated work rate situations.

Some occupational health hazards resulting from an elevated rate of work due to recent mechanization and automatization are discussed on the basis of results of health examinations. A rapid increase of a cervicobrachial disorder among young cash register and packing machine operators has been observed. Switching to the use of electronic cash registers has been shown to have only limited efficacy due to increased operation speed, and high-speed complex finger and hand movements of packer operators have also proven to be as hazardous as key-board operations. The high incidence of low-back pain, in particular gradually developing pain, among workers in electric power supply work has been suggested to be the result of quick and intensified work to meet increasing supply demand. Likewise, the workload of electric locomotive and bullet train drivers has increased in accordance with increased train speeds, and has been shown to have had significant effects on their health particularly in regards to neural strain, intra-cab environment such as air pressure change, vibration, and noise, and rotation on irregular shifts. New steps seem required therefore to meet the new health problems arising from a combination of modern technological changes and elevated working speeds.

Atmospheric Pressure↗
PubMed1975

Inhibition of granulation tissue growth by histamine.

Granulomas were induced in rats by subcutaneous implantation of formalin-soaked filter-paper disks. Daily subcutaneous injection of histamine at doses of two times 0.05 mg/kg and above inhibited the growth of granulation tissue as measured by a marked decrease in the dry-defatted granuloma weight and of the hydroxyproline and hexosamine content. Histological observations of granulation tissue indicated that histamine inhibited the proliferation of fibroblasts and the formation of capillaries. Inhibitory effects were also observed with the histamine releaser, sinomenine, and the histaminase inhibitor, aminoguanidine. These histamine effects seem not to be mediated by glucocorticoid release, since an effective dose level of histamine produced no change in growth or thymus weight. Prednisolone was less potent than histamine in inhibiting Prednisolone was ineffective at the dose tested. Subcutaneous injection of the H2-receptor antagonist, burimamide, blocked these histamine effects and also of sinomeinine and aminoguanidine. The H1-receptor antagonist, mepyramine, did not block these histamine effects. Burimamide alone enhanced the growth of granuloma. These results indicate that granulation-tissue growth in inflammation is affected by the inhibitory effect of endogenous histamine acting through H2-receptors.

Amine Oxidase (Copper-Containing)↗