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Biomedical subjects

D Chase

Publications and source records attributed to D Chase.

At least 55 records · Page 3Linked to original sources
PubMed1986

Transplantation of fetal fibroblasts and correction of enzymatic deficiencies in patients with Hunter's or Hurler's disorders.

An attempt was made at correcting the specific lysosomal enzyme deficiencies in 7 children with Hunter's or Hurler's diseases by transplantation of fetal fibroblasts. In spite of pretreating the young patients with stored blood, following a procedure employed successfully to avoid rejection of kidneys from incompatible donors, the use of serum-free media for culturing the cells before being harvested and incubation of the cells with chorionic gonadotrophin, the transplantation of fetal fibroblasts was not associated with biochemical or clinical changes. None of the seven patients showed immune reactions against the transplanted cells, HLA antigens, or the missing enzymes.

Animals↗
PubMed1983

beta-Adrenergic catecholamine-dependent properties of rat myometrium primary cultures.

We have used cultured trypsin-collagenase-dispersed cells from uteri of 21-day-old rats to investigate the mechanism of control of uterine motility by the beta-adrenergic receptor. After 5 to 7 days in RPMI 1640 the cells started to assume some of the morphological characteristics of smooth muscle cells. When cultures were incubated with 45Ca2+ for 3 h then washed free of isotope and incubated in medium with unlabeled Ca2+, efflux from the prelabeled intracellular pools was linear for up to 60 min. The potent beta-adrenergic agonist isoproterenol had a rapid effect on the rate of efflux and increased it almost sevenfold. Isoproterenol's effect was blocked by propranolol and could be duplicated by the addition of 8-bromo-adenosine 3',5'-cyclic monophosphate or cholera toxin. The cultured myometrial cells had adenylate cyclase properties similar to those of intact muscle strips when these were determined by the conversion of radioactive substrate (alpha-32P-ATP) to 32P-cAMP using a broken-cell preparation. Adenylate cyclase was sensitive to stimulation by GTP and by isoproterenol in the presence but not in the absence of GTP. Adenylate cyclase was also sensitive to stimulation by Ca2+ in the absence of GTP. We conclude that the primary cultures had the properties expected of smooth muscle cells including beta-adrenergic receptors that were coupled to a physiologically important function, Ca2+ flux. The beta-adrenergic receptor's effect on Ca2+ flux was cAMP mediated, and the divalent cation may also regulate its rate of flux by an effect on Ca2+-sensitive cAMP production.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1981

Contractile properties of fast muscle preparations regenerating in slow muscle beds.

Mechanical evidence is presented to show that fast muscle tissue regenerating in the bed of a slow muscle, and innervated by the slow muscle nerve, has contractile properties identical to those of a slow muscle regenerating in its own bed. The results do not support the idea that regenerating fast muscles are partially resistant to the transforming effects of a slow nerve.

Animals↗
PubMed1981

Repositioning of fast and slow skeletal muscle.

The origins of the rat fast plantaris and slow soleus muscles were surgically reversed and their fibre types and contractile properties examined in vitro up to 12 weeks post surgery. Muscles in which the origins had been severed and then immediately sutured back in place served as one control group. Unoperated animals served as a second control group. As compared to these groups, no significant differences in the histochemical or mechanical properties of the repositioned muscles were detected. Under the conditions of the experiments, no evidence was obtained to indicate that the intrinsic properties of a muscle could be altered by changing its site of origin and thus its functional environment.

Animals↗
PubMed1981

Mechanical properties of tenotomized and denervated-tenotomized muscles.

Mechanical properties of rat soleus and plantaris muscles were studied in vitro following tenotomy, denervation, or tenotomy plus denervation, all of 3 wk duration. Controls included muscles from sham-operated animals and from animals with muscle tendons severed but immediately resutured. Results of twitch times, times to peak tension, and times to half-relaxation for 145 muscles clearly showed that the slight increase in muscle speed that occurs in the soleus muscles only is due to severance of the muscle tendon per se and not related to muscle shortening and possible related alterations in muscle spindle activity that occurs in simple tenotomy. Furthermore, any demonstrable mechanical changes that occur with tenotomy or with section and resuturing of the tendon requires the presence of intact innervation. We conclude that, contrary to published opinion, tenotomy does not transform slow contracting muscles into fast contracting muscles and that comments concerning the role of stretch receptors in this postulated transformation are pure conjecture, unsupported by experimental data.

Animals↗
PubMed1980

The symbiotic microbial community of the Sonoran Desert termite: Pterotermes occidentis.

Pterotermes occidentis is a large, obscure, very primitive dry wood termite limited to the Sonoran desert of North America. Its development, caste system and behavior are discussed in relation to aspects of its ecology. What appear to be single wood-digesting individual termites are in fact insect hosts which harbor extensive microbial communities estimated to contain more than 40 interacting species. All healthy, wood-eating Pterotermes contain these densely populated communities of highly motile symbionts suggesting that species diversity is necessary for termite survival. A morphological catalogue of the major hindgut microbes is presented here. From 10(7) to 10(11) bacteria and from 10(3) to 10(6) protists/ml of hindgut fluid are found in an average nymph or larva. The species of four wood-ingesting mastigotes (genera Trichonympha, Metadevescovina, Tricercomitus and Microrhopalodina) and nearly 30 morphologically distinct types of bacteria are described. The description of this morphological diversity observed with light, scanning and transmission electron microscopy is a prerequisite to functional analyses of the symbioses. Since Pterotermes is easily maintained in the laboratory and is so large it is hoped that it will provide a useful model for symbiosis research.

Animals↗
PubMed1979

Possible evolutionary significance of spirochaetes.

Large symbiotic spirochaetes of the family Pillotaceae (e.g. pillotinas) are found in dry wood and subterranean termites (Hollande & Garagozlou 1967). These morphologically distinctive spirochaetes comprise several genera. Some of them contain microtubules within their protoplasmic cylinders. They demonstrate a variety of relations with their termite and protist hosts. Some are free-living within the lumen of the intestine, some tend to be associated with filamentous and other bacteria, some are found regularly coursing between the numerous undulipodia ( = eukaryotic flagella, cilia, and other (9 + 2) organelles of motility) of hypermastigotes and polymastigotes. Still other smaller termite spirochaetes are regularly attached to protists via specialized attachment sites. Some even form motility symbiosis with their host protists. The analogy between the behaviour of host-associated spirochaetes and the possible steps in the origin of the undulipodia and mitotic system of eukaryotes is discussed briefly.

Biological Evolution↗
PubMed1978

Microtubules in prokaryotes.

Longitudinally aligned microtubules, about 220 A in diameter, have been seen in the protoplasmic cylinders of the following spirochetes (symbiotic in the hindguts of dry-wood and subterranean termites): Pillotina sp., Diplocalyx sp., Hollandina sp. They are also present in a gliding bacterium from Pterotermes occidentis. These microtubules are probably composed of tubulin, as determined by staining with fluorescent antibodies to tubulin and comigration with authentic tubulin on acrylamide gels. Treponema reiteri lack tubulin by these same criteria. These observations support the hypothesis of the symbiotic origin of cilia and flagella from certain spirochetes.

Animals↗
PubMed1977

Ventricular tachycardia in a neonate with mepivacaine toxicity.

An unusual case of mepivacaine toxicity with ventricular tachycardia in a newborn infant is presented. The mepivacaine probably reached the infant by direct injection into the scalp. Effective removal of the drug by gastric lavage was demonstrated. Exchange transfusion may also have been instrumental in the infant's survival by reducing the high blood concentration of mepivacaine.

Anesthesia, Obstetrical↗
PubMed1976

Potential partners: attitudes of family practice residents toward collaboration with social workers in their future practices.

The study examines attitudes of family practice residents toward social work collaboration in their practices. Residents valued social work services highly, and almost three-fourths want a social worker in practice with them. Residents valued the broad range of services offered by social workers, and over half could see no disadvantages to such collaboration.

Attitude of Health Personnel↗