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Biomedical subjects

J B Jones

Publications and source records attributed to J B Jones.

At least 163 records · Page 9Linked to original sources
PubMed1977

Methanococcus vannielii: ultrastructure and sensitivity to detergents and antibiotics.

Methanococcus vannielii is a strictly anaerobic motile coccus that possesses a tuft of flagellae. The cells are markedly sensitive to mechanical stress and are readily lysed by detergents, but the organism grows normally in media of low ionic strength. The absence of a typical cell wall, further suggested by resistance of M. vannielii to penicillin, cycloserine, and vancomycin, was confirmed by ultrastructural studies. Electron micrographs showed that the cell envelope lacks a peptidoglycan layer. On the outer surface there is a regular array of subunits similar to those of the glycoprotein envelopes of the halobacteria. However, the M. vannielii cell envelope, unlike those of the holobacteria, is unable to maintain a definite shape, and a high salt concentration is not required for its integrity.

Anti-Bacterial Agents↗
PubMed1977

Progenitor cells in canine cyclic hematopoiesis.

Granulocytic (colony-forming units in culture, or CFU-c) and erythrocytic (erythropoietin-responsive cells, or ERC) progenitor cells in canine cyclic hematopoiesis (CH) have been shown to fluctuate over the cycle and in the same phases as one another. The ERC cycle is preceded by 3 or 4 days by a rise in serum erythroid-stimulating activity and is followed by a reticulocytosis. During the cycle CFU-c show a differential sensitivity to two sera, one normal and one containing elevated amounts of colony-stimulating activity. The proliferation rate of CFU-c also fluctuates from well above normal to considerably less than normal over the cycle. These results are discussed in the light of present knowledge of the pathogenesis of canine CH. We suggest that these results support the contention that CH is a disorder of hemopoietic stem cells and that the cycling of humoral factors and peripheral blood cells may follow as a consequence.

Animals↗
PubMed1976

Quantitative study of lymphoreticular infiltration into canine transmissible venereal sarcoma.

Lymphoreticular cell (LRC) infiltration into tumour masses at different stages of growth after transplantation was studied in canine transmissible venereal sarcoma (CTVS). The percent viable LRC of total viable cells in tumour suspensions shows an inverse correlation with the logs of tumour mass of adult dogs (R = -0.475, phi = 28, P less than 0.01), which suggests that the degree of LRC infiltration is a measure of the host immune response. However, an estimate of the surface area (S.A.) of the tumour rather well perfused with blood elements based on the formula S.A. = 5.43 (tumour mass in g)2/3 showed that the LRC mass present in a tumour was a function of its surface area. Thus, the inverse correlation of the percent viable LRC's in a viable tumour cell suspension to the log of the CTVS mass might not necessarily indicate that the infiltrated LRC's were active as immune effector cells. The correlation does show that, as the CTVS size increases, the volume of the necrotic center increases more rapidly than the volume perfused with blood and, therefore, the percent viable LRC's in CTVS decreases with CTVS size increase.

Animals↗
PubMed1976

Platelet mono-amine oxidase activity in the human fetus.

Measurement of the platelet mono-amine oxidase (MAO) activity in the human fetus of 40 weeks gestation showed it to be equivalent to that found in the adult. The level represents a fully-developed mitochondrial MAO system in platelets and may reflect enzyme maturity in other tissues of the newborn.

Blood Platelets↗
PubMed1976

Monoamine oxidase activity in the fetal lung and liver.

Monoamine oxidase (MAO) in lung and liver is important in the degradation of circulating 5-hydroxytryptamine. These sites of MAO activity have been investigated histochemically in the human fetus of 12 to 18 weeks gestation. Enzyme activity could be demonstrated in the liver by both tryptamine and adrenaline oxidation. In the lung, MAO activity was present only when adrenaline was used to substrate. It may be, therefore, that in the premature baby the capacity of MAO to metabolize 5-hydroxytryptamine is not fully developed, which could lead to deleterious effects on pulmonary function.

Epinephrine↗
PubMed1976

Hormonal control of erythropoiesis in canine cyclic haematopoiesis.

The results of erythropoietin (ESF) studies in dogs with cyclic haematopoiesis are presented. Even though the dogs were exposed to a constant stimulus of hypoxia, cycles in the plasma ESF levels occurred at 11 to 12 day intervals. In some dogs, minor midcycle peaks were observed and the amount of ESF produced varied with the different animals. The peaks of ESF characteristically appeared approximately five days after onset of neutropenia. A hypothesis is presented to explain the known facts concerning canine cyclic haematopoiesis. It suggests that a poietin controlling factor is produced and that this assumed factor then stimulates the production of specific factors leading to increases of reticulocytes, platelets, and monocytes. The monocytes in turn produce more colony stimulating factor (CSF) leading to the formation of granulocytes. Such a sequence of events would explain the apogee of reticulocyte, platelet, and monocyte counts at a time when the nadir of granulocyte counts is reached.

Animals↗
PubMed1976

Erythropoiesis and erythrocytic survival in dogs with cyclic hematopoiesis.

Erythrocytic survival and ferrokinetic studies were carried out in dogs with cyclic hematopoiesis. The serum iron values varied during different phases of the cycle. The highest values occurred when the bone marrow predominantly contained granulocytic cells. The erythrocytic survival and the remainder of the ferrokinetic variables were comparable to those in normal dogs of a similar age.

Agranulocytosis↗
PubMed1975

Cyclic hematopoiesis in a colony of dogs.

A laboratory-maintained colony of dogs heterozygous for cyclic hematopoiesis (ch) has been established. The colony consists of Collies and Collie-Beagle mixed dogs. Matings between dogs heterozygous for ch resulted in 110 pups, 28 of which were homozygous for ch. Each of the 28 homozygous ch pups (15 females and 13 males) was gray and white. Ninetten of them survived the preweaning period and were found to have cyclic fluctuations of neutrophils, platelets, and reticulocytes.

Animals↗