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Biomedical subjects

D F Wilson

Publications and source records attributed to D F Wilson.

At least 253 records · Page 14Linked to original sources
PubMed1978

Ultrastructure of odontogenic keratocysts.

The ultrastructural features of an odontogenic keratocyst are described. The results of the investigation suggest that the basal lamina complex in the odontogenic keratocyst appears to be morphologically normal. The frequently observed splitting of the epithelium from the capsular tissue is marked by the separation of the epithelium and the basal lamina complex from the connective tissue. The morphologic features of the parakeratinized surface zone of the epithelium suggest that the odontogenic keratocyst may be characterized by "incomplete" parakertinization.

Adult↗
PubMed1978

Energy relationships between cytosolic metabolism and mitochondrial respiration in rat heart.

Isolated rat heart was perfused with Langendorff's retrograde perfusion method, while the oxygen consumption and the left ventricular pressure were monitored continually. The steady-state contents of metabolites in the cardiac tissue, freeze clamped under various work-load conditions, were determined and the concentrations of free cytosolic ADP and AMP were calculated from the near equilibrium in creatine phosphokinase and adenylate kinase reactions. Increasing respiratory rate with increasing load was accompanied by a fall in the cytosolic free [ATP]/[ADP][Pi] but little change in the mitochondrial free [NAD+]/[NADH]. The free energy of ATP hydrolysis was calculated from the concentrations of the adenine nucleotides and compared with the values computed from the measured turnover number for cytochrome c and redox state of the mitochondrial NAD couple according to a mathematical model. The agreement between the two values was good over a wide range of metabolic conditions, which provides further support for the proposed near-equilibrium model of mitochondrial respiration with control exerted at the cytochrome oxidase-oxygen reaction.

Adenine Nucleotides↗
PubMed1978

Homeostatic regulation of cellular energy metabolism: experimental characterization in vivo and fit to a model.

Measurements in isolated liver cells, cultured kidney cells, protozoa (Tetrahymena pyriformis), and yeast (Candida utilis) indicate that homeostatic regulation of cellular energy metabolism is of common origin. In every case near equilibrium is maintained between the transfer of reducing equivalents from the intramitochondrial NAD couple to cytochrome c and the phosphorylation of cytosolic ADP to ATP. Under conditions of constant energy demand, changes in the intracellular phosphate concentration cause an adjustment in the [ATP]/[ADP] to maintain a constant [ATP]/[ADP][Pi] and constant respiratory rate. The regulation of mitochondrial respiration occurs as part of the reactions by which reduced cytochrome c is oxidized by molecular oxygen. At similar values for the [ATP]/[ADP][Pi] the respiratory rate increases with increasing reduction of cytochrome c. A model for mitochondrial respiratory control is found to give a good fit to the data in all of the different types of cells tested.

Adenine Nucleotides↗
PubMed1978

Evaluation of oxidative phosphorylation in hearts from euthyroid, hypothyroid, and hyperthyroid rats.

The energy relationships between cytosolic and mitochondrial metabolism were studied in the hearts from euthyroid, hypothyroid, and hyperthyroid rats. Isolated mitochondria showed high respiratory control ratios and impermeability to exogenous NADH. Hypo- and hyperthyroidism, respectively, resulted in lower and higher contents of both cytochromes per mitochondrion and mitochondrial protein per gram of wet weight of heart without changes in the ratio of cytochrome c to cytochrome aa3. In isolated perfused heart, the hyperthyroid state led to an increase in work rate and thereby an elevation of Vo2, which resulted in an increase oxidation-reduction turnover number for the cytochromes. An agreement was found between [ATP]/[ADP][Pi] of cytosolic free adenine nucleotides and the value calculated from a mathematical model of mitochondrial respiration. This implies that mitochondrial respiration is controlled at the cytochrome oxidase reaction and that oxidative phosphorylation in intact tissue is tightly coupled irrespective of thyroid state. It is concluded that thyroid hormone causes an increase in the mitochondrial mass, mitochondrial cytochrome content, and respiratory rate, and consequently expands the capacity of oxidative metabolism without an uncoupling effect on oxidative phosphorylation.

Adenine Nucleotides↗
PubMed1977

Prevalence of seropositive reactions to Brucella canis in a limited survey of domestic cats.

The prevalence of Brucella canis agglutinins was determined in 170 cats (114 from animal shelters in California and 56 from an animal hospital in Texas). Seropositive reactions in the cats from animal shelters were 5.3, 11.4, and 0%, respectively, the the rapid slide agglutination test, salt 2-mercaptoethanol tube agglutination test, salt 2-mercaptoethanol tube agglutination test, and brucellosis card test. For hospitalized cats, the respective percentages were 7.1, 8.9, and 0%. One (0.9%) of 114 cats from the animal shelters and 5 (8.9%) of 56 hospitalized cats were seropositive by the salt 2-mercaptoethanol tube agglutination test at titers greater than or equal to 1:200. Isolation of bacteria was not attempted; thus, the findings of this study may need cautious interpretation.

Agglutination Tests↗
PubMed1977

Effect of oxygen tension on cellular energetics.

Simultaneous measurements of the mitochondrial [NAD+]/[NADH], the cytoplasmic [ATP]/[ADP] x [Pi], and the respiratory rate were carried out in suspensions of cultured kidney cells in a range of defined oxygen tensions. The results show that as the extracellular oxygen concentration falls there is a decrease in the respiratory rate, which is accompanied by a decrease in the [ATP]/[ADP] and a progressive reduction of cytochrome c. Even at low O2 tensions the mitochondrial respiratory chain between the NAD couple and cytochrome c remains at near equilibrium with the ATP synthesizing reactions. It is concluded that limited oxygen supply affects cellular metabolism at much higher concentrations than the P50 value for the oxygen dependence of respiration, but the respiratory rate remains relatively unchanged due to compensatory changes in the [ATP]/[ADP] X [Pi] and progressive reduction of cytochrome c. These metabolic changes may form a basis for the phenomenon of tissue oxygen sensing at near physiological oxygen tensions.

Adenine Nucleotides↗
PubMed1977

Estimates of quantal-release and binomial statistical-release parameters at rat neuromuscular junction.

Quantal-release and binomial statistical-release parameters were examined in the isolated rat diaphragm phrenic nerve preparation. The muscle resting potentials were reduced by cutting the muscle fibers to prevent muscle action potentials and contractions. The cutting technique was modified to allow persistent observation of miniature end-plate potentials (MEPPs) and end-plate potentials (EPPs) with intracellular recording techniques. Direct estimates of quantal release were examined and compared with predicted binomial and Poisson distributions. The results indicate that release is binomial when the nerve is stimulated with low- or high-frequency stimuli. The indirect method of estimating quantal release (variance method), which assumes release is described by a Poisson distribution, seriously overestimates quantal release. The binomial analysis indicates that the statistical store is small (less than 90 quanta) and that most of these quanta are released with each nerve impulse.

Animals↗