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Biomedical subjects

P G Lundquist

Publications and source records attributed to P G Lundquist.

At least 19 recordsLinked to original sources
PubMed1992

Studies on the regranulation of salivary gland serous cells. An electron microscopical study in the rat.

The degranulation and regranulation process was investigated after alpha-adrenergic stimulation on the rat submandibular gland. The submandibular gland in rat contains both serous and mucous cells. It has earlier been shown that serous cells filled with heavy-metal granules, are markedly more radiosensitive than cells without granules. In experiments with emptying the serous cell of their content of granules by administering an alpha-adrenergic stimulant, cyclocytidine, there has been found a decrease in irradiation damage in salivary gland tissue after irradiation. Injection of cyclocytidine, 150 mg/kg, was given i.p. to the rat. After 1 h there was almost complete depletion of granules in the serous cells, no morphological aberration was seen in the mucous cells. This effect still remained after 6 h. A beginning of regranulation with apical granules was seen 12 h after injection. After 24 h an almost complete regranulation had occurred in the salivary gland serous cells. The mucous cells did not show any morphological aberration. Our intent is to reduce unwanted salivary gland damage in patients with head and neck cancer when treated with radiotherapy. Depletion of heavy-metal granules in serous cells, before irradiation may diminish morphological destruction in the salivary glands. As a nearly total degranulation is present between 1-6 h after stimulation, this should be the optimal time for radiotherapy.

Ancitabine↗
PubMed1989

Aspects of salivary gland radiosensitivity: effects of sialagogues and irradiation.

Rat submandibular glands were exposed to fractionated irradiation of 50 Gy, as given comparably in clinical practice. The induced changes were compared by giving only irradiation or radiation in conjunction with stimulating the salivary glands with cyclocytidine prior to treatment. Cyclocytidine is an alpha-adrenergic agonist that effectively depletes the serous cells of their granules and their heavy metal content. Findings in the present study show that the administration of the drug prior to each irradiation reduces the radiation-induced destruction in the epithelial cells in the submandibular gland.

Ancitabine↗
PubMed1988

Radiation-induced decreases of serous cell immunoglobulin excretions in the rat submandibular gland.

The effect of radiation on the submandibular glands of the rat was studied with special reference to the immune reactivity of IgG and IgA. These immunoglobulins are localized in the serous cells and were influenced by irradiation. Radiation therapy markedly reduced the reactivity for both IgG and IgA. Immunocytochemistry showed a good correlation to the deteriorated morphology as revealed by light and electron microscopy. The local excretion of immunoglobulins in the submandibular gland can thus be affected by radiation and results in an increased risk for oral infections. Pretreatment of animals with the secretagogue cyclocytidine caused less pronounced damage in cellular ultrastructure and immunological findings, as observed by fluorescence microscopy.

Ancitabine↗
PubMed1988

An ultrastructural study of salivary gland radiosensitivity after alpha-adrenergic stimulation.

The submandibular glands in 32 rats were exposed to either fractionated irradiation comparable to 50 Gy or a single fraction of 50 Gy. Prior to irradiation half the rats were given cyclocytidine, an alpha-adrenergic agonist which depletes serous cell granules. The results suggest that irradiation causes a significant, irreversible destruction of serous cells. Visible morphological changes were: intracytoplasmic vacuoles, destroyed mitochondria with disrupted cristae and derangement of the endoplasmic reticulum. Animals treated with cyclocytidine had diminished radiation injury. This drug may act as radioprotector, depleting secretory heavy metal granules, reducing radiation damage in the submandibular salivary glands.

Adrenergic alpha-Agonists↗
PubMed1988

Salivary gland morphology after alpha-adrenergic and cholinergic stimulation. An ultrastructural study.

The submandibular glands in 100 rats were subjected to different sialagogues: carbachol, clonidine, noradrenalin, and cyclocytidine. The morphological effects of these drugs were compared ultrastructurally. Clonidine, which is an alpha-2-agonist affected mostly the mucous cells, with formation of cytoplasmic vacuoles between the mucous droplets. Noradrenalin and cyclocytidine, both alpha-1-agonists, showed depletion of secretory granules in the serous cells. Noradrenalin also induced cytoplasmic disorganization with enlarged mitochondria, irregular endoplasmic reticulum, and shrinking of the secretory lumen. Carbachol, a cholinergic agonist, was found to produce widespread vacuolization in the cytoplasm of both serous and mucous cells. Small vesicles appeared and mitochondria were destroyed. To induce experimentally a complete depletion of granular serous cells, without other changes in ultrastructural morphology, cyclocytidine was found to be the most efficient drug.

Adrenergic alpha-Agonists↗
PubMed1979

Tinnitus caused by bilateral shunts from the occipital arteries to the intracranial veins. A case report.

A patient with objective tinnitus and a pulse synchronous murmur over both left and right sides of the mastoid regions is described. Microphones placed over the mastoid regions recording "phonomastoidograms" clearly demonstrated the pulse synchronous tinnitus. Arteriovenous shunts from the occipital arteries to the sigmoid sinus were later demonstrated with angiograms. After bilateral surgical removal of the arteriovenous shunts the incapacitating tinnitus disappeared. The importance of thorough examination of pulse synchronous tinnitus is discussed.

Arteriovenous Fistula↗
PubMed1978

Ultrastructure of salivary calculi.

Twenty-one submandibular salivary calculi from 19 patients were examined with the light and electron microscope. Adjacent to the peripheral parts of the calculi metaplastic squamous epithelium or connective tissue was seen in close contact to the mineralized matrix. Disintegrated cellular substances from these tissue components were in some cases found to condense in a peripherally located zone of the salivary calculi. The morphology of the examined salivary calculi varied extensively not only within each calculus but also from one calculus to another. High and low incidence of crystals gave rise to the lamellated pattern. In some cases the crystals were so abundant as to five a dense homogeneous appearance. In the central parts of the calculi spheroid bodies of very low electron density with a size ranging from 1 to 100micrometer were found in an amorphous matrix. The origin of these structures is discussed. In the peripheral parts of some calculi osmiophilic spherical bodies with an electron microscopical appearance similar to lipid granules as well as bacteria of cocci or coliform type were found. Degenerated bacteria might in some cases contribute in forming part of the peripheral organic matrix.

Humans↗
PubMed1978

Experimental studies on fluid pathophysiology in small intestinal obstruction in the rat. IV. Effects of intraluminal hyperosmolality and simultaneous intravenous infusions on mucosal micromorphology.

A hyperosmolal glucose solution was introduced into a loop of small intestine of specified length and position while intravenous infusions of varying osmolality were given at the same time. The hyperosmolal solution in the lumen caused damage primarily to the tips of the villi where sloughing of the epithelial cells was frequently seen. These defects were repaired by an increase in surface coverage by neighboring epithelial cells, which thus were reduced in height. A varying degree of edema was generally seen in the epithelial cells. The severity of these lesions was modified by intravenous infusions in inverse relationship to the osmolality of the infusions. Thus the defence mounted by the intestinal mucosa against the hyperosmolal solution in the lumen was impaired by the infusion of hypo-osmolal solutions and improved by hyperosmolal solutions. In the latter cases the mucosa maintained a practically normal histological picture.

Animals↗
PubMed1977

The influence of different fixatives and osmolality on the ultrastructure of the cochlear neuroepithelium.

To investigate which fixative is most suitable for the preservation of cochlear hair cells three main groups of fixatives were used: 1. 3% glutar aldehyde in various buffers (osmolality altered). 2. Glutar aldehyde/paraform aldehyde combination (ad modum Karnovsky). 3. Osmic acid solutions (OsO4) in veronal acetate buffer according to Rhodin (1954). The 2% osmic acid fixative (350--370mosm/kg) resulted in an excellent ultrastructural preservation; an acceptable result was obtained with a 3% glutar aldehyde fixative in 0.1 M sodium phosphate buffer, 600--700 mosm/kg and the Karnovsky's fixative.

Animals↗
PubMed1977

Evidence for the existence of self-reactive human B lymphocytes.

Supernatants from human tonsil cells cultured in the presence of the PBAs, LPS and F (ab)2 monomers of rabbit anti-human beta2-microglobulin were found to have a complement-dependent cytotoxic activity to tonsil cells of the same donors. A direct toxic effect of the PBAs on the target cells was excluded by controls. Therefore the most likely explanation for this finding is that human lymphocytes contain a subpopulation of self-reactive B cells which can be triggered by PBAs to release antibodies to self-antigens. The implications of this finding for the understanding of infections accompanied by auto-immune phenomena are discussed.

Antibody Formation↗
PubMed1976

Aspects on endolymphatic sac morphology and function.

Morphological evidence indicate that the main function of the endolymphatic sac is to act as a reabsorptive and defensive mechanism for the inner ear. This activity is markedly enhanced in labyrinthine trauma, such as injection of foreign particles into the labyrinth, blocking of the endolymphatic duct, and cryosurgical destruction of vestibular sensory epithelia. Light and dark epithelial cells of the intermediate portion of the sac are capable of reabsorbing endolymph and digesting cellular debris respectively. The extensive capillary network surrounding the endolymphatic sac exhibits endothelial characteristics suggestive of active fluid transport. The "dynamic-flow theory" of endolymph circulation suggests that a radial-flow should be considered for energy metabolism and ion exchange around the sensory cell regions whereas a longitudinal-flow should be considered for reabsorption of endolymph and disposal of high molecular waist products and debris by the endolymphatic sac. The earlier concepts of endolymph circulation thus need not any longer be considered conflicting.

Ear, Inner↗