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D Dillon

Publications and source records attributed to D Dillon.

At least 37 records · Page 2Linked to original sources
PubMed1991

Spontaneous mutation at the mtr locus of Neurospora: the spectrum of mutant types.

We have isolated 135 strains of Neurospora which have mutations at the mtr locus resulting from independent spontaneous events. mtr is the structural gene for the neutral amino acid permease. The mutants have been characterized by their reversion behavior (both spontaneous and induced) and by hybridization studies of restriction digests of their DNA. About half of the mutants (54%) appear to result from single base-pair substitutions. Thirty-four percent have deletions, including some which extend into neighboring genes. Most of the remaining mutants have insertions. Several of the insertions are tandem duplications of 400-1000 bp and these mutants are unstable, reverting to mtr+ with a high frequency. When tandem-duplication mutants go through a cross, they are modified: the mutant progeny are fully stable. This modification is probably due to RIP (repeat-induced point mutation). This process has an important bearing on the comparison of germinal to somatic mutation.

Aminoacridines↗
PubMed1991

Myocardial aging: antioxidant enzyme systems and related biochemical properties.

The effects of aging on myocardial antioxidant enzyme activity, lipid peroxidation, and other related biochemical properties were investigated in male Wistar-Furth rats at 4, 26, and 31 mo of age at rest and after an acute exercise bout. The results showed that resting heart cytosolic superoxide dismutase (CuZn SOD) activity was significantly decreased in the heart with aging (66 +/- 6.5 U/mg protein at 4 mo vs. 49 +/- 3.8 U/mg protein at 31 mo) and was elevated in all age groups after exercise. Mitochondrial Mn SOD activity was almost doubled in both 26- and 31-mo-old rats compared with that at 4 mo. Myocardial catalase and cytosolic glutathione peroxidase (GPX) activities were significantly decreased with age, whereas mitochondrial GPX was 29% higher (P less than 0.05) in 31- than 4-mo-old rats. Glutathione S-transferase activity in the heart also declined with age (P less than 0.05 at 31 mo). Malondialdehyde contents in both heart homogenate and mitochondria were significantly increased at old age. Activity of several enzymes related to myocardial energy production, e.g., citrate synthase, malate dehydrogenase, and lactate dehydrogenase, as well as myocardial protein content showed an age-related decline. These data indicate that myocardial antioxidant capacity is weakened during aging and that the compensatory increases of mitochondrial SOD and GPX may be an important mechanism in coping with free radical damage in senescent heart. Findings in the present investigation seem to support the free radical theory of aging.

Aging↗
PubMed1990

Alteration of antioxidant enzymes with aging in rat skeletal muscle and liver.

Maximal activities of antioxidant enzymes involved in oxygen free radical metabolism in skeletal muscle and liver were investigated in 4-, 26-, and 31-mo-old male Wistar-Furth rat at rest and after a single bout of treadmill exercise. In skeletal muscle, cytosolic (Cu-Zn) and mitochondrial (Mn) superoxide dismutase (SOD) specific activities were significantly higher in the aged rats and at 31 mo reached 135 and 218%, respectively, of those at 4 mo. Resting catalase activity was doubled at 31 mo compared with that at 4 mo. Glutathione peroxidase (GPX) activity increased twofold in muscle cytosol and by 47% in mitochondria of aged rats. Glutathione S-transferase (GST), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G-6-PDH) activities in muscle were also significantly elevated. Hepatic antioxidant enzymes were altered differentially with aging. Cytosolic SOD and GST activities were decreased, whereas mitochondrial GPX, GR, and G-6-PDH activities were increased. Lipid peroxidation was greater in skeletal muscle homogenate and mitochondria but lower in liver homogenate in the aged rats. An acute exercise bout had little effect on muscle or liver antioxidant enzymes regardless of the animal's age. It is concluded that aging is accompanied with an elevation of antioxidant enzyme activities and lipid peroxidation in skeletal muscle probably due to the increased oxygen free radical production and reaction.

Aging↗
PubMed1990

Sodium D-lactate infusion of panic disorder patients.

Nineteen patients with panic disorder received sodium D,L-lactate (racemic) and pure sodium D-lactate infusions in a pilot study. Sodium D-lactate, which is less metabolically active than L-lactate, produced panic attacks in half the patients. D-Lactate also produced hypocapnia and alkalosis, indicating hyperventilation. These findings suggest that metabolism of lactate is not necessary for the induction of panic in susceptible patients. D-Lactate appears similar to other agents that cause panic in its capacity to stimulate respiration in the preliminary study.

Adult↗
PubMed1988

The alloantibody response to semiallogeneic pregnancy in the rat. I. Alloantibodies in sera and placental eluates directed to RT1A antigens.

Maternal alloantibodies to paternal cells were monitored by cellular ELISA, the indirect hemagglutination and erythrocyte antibody rosette inhibition assays in sera and placental eluates from primigravid and multigravid inbred rats. In primigravid animals, antibodies in sera were routinely detected only by the indirect hemagglutination assay and were of low titer; weak antibody activity was detectable only by indirect hemagglutination in 1 of the 8 placental eluates assayed from these animals. Alloantibodies in high titer were present in sera and placental eluates from multigravid rats and were found to be directed predominantly to the RT1A (class I MHC) antigens of the paternal strain. These data provide no support for the hypothesis that the difficulty in detecting maternal antibodies during a 1st pregnancy is due to their preferential binding to antigenic determinants expressed on the placenta.

Animals↗
PubMed1987

Antipanic drug effects during lactate infusion in lactate-refractory panic patients.

In previous articles we have reported on the total Acute Panic Inventory (API) score during lactate-induced panic. Even patients with panic disorder who do not panic during lactate infusion have higher API scores during the infusion than normal controls. In this post hoc analysis, we wished to determine whether specific API items were more sensitive to the beneficial effects of antipanic medication, either at baseline or during the infusion, in these lactate-insensitive panic patients. Four of the 17 items showed specific drug blockade of baseline severity. Five additional items showed specific drug blockade of lactate exacerbation of symptom severity. Medication apparently had no effect on severity of the remaining eight items. We suggest that the nine symptoms that responded to drug therapy are associated with hyperventilation. The study indicates that antipanic drugs may have a specific effect in blunting hyperventilation.

Adult↗
PubMed1986

Possible mechanisms for lactate's induction of panic.

Forty-three patients with panic disorder or agoraphobia with panic attacks and 20 control subjects received 0.5 M racemic sodium lactate intravenous infusions, single-blind as to duration and sequence. During the procedure, pulse; blood pressure; blood L-lactate and pyruvate; plasma ionized calcium, phosphate, prolactin, epinephrine, norepinephrine, and cortisol levels; and venous PCO2, pH, and bicarbonate were measured in an attempt to clarify the mechanism of lactate-induced panic attacks. During the infusion, 72% of the patients but none of the control subjects had panic attacks. The laboratory findings suggest that peripheral catecholamine surge is not the mechanism by which lactate causes panic, although elevated epinephrine may be a predisposing factor. Heightened central noradrenergic activity was present in many but not all of the attacks. Contrary to previous hypotheses, neither depression of ionized calcium nor induction of metabolic alkalosis appears sufficient to cause panic during lactate infusion.

Agoraphobia↗
PubMed1986

Health, vocational, and functional status in spinal cord injured athletes and nonathletes.

The relationship of sports involvement to medical complications, functional independence, and vocational status was studied in 67 individuals from 2 to 24 years after spinal cord injury (SCI). Sports participation ranged from none to 30 (means 7.6) hours/wk. No significant correlation was found between time spent in sports participation and number of medical complications, rehospitalizations, functional status, or employment. Subsequently, subgroups of SCI wheelchair basketball players (n = 19) and SCI nonathletes (n = 19) were compared in medical, functional, and vocational status. The athlete group showed significantly more average time per week of sports participation (p less than 0.03), as expected. Fewer physician visits (p less than 0.01) occurred in the athlete group. Trends toward fewer medical complications and fewer rehospitalizations were seen in the athletic group, but this did not reach statistical significance. Sports participation was not associated with increased risk of medical complications and did not limit available time for vocational pursuits. The positive benefits of sports involvement on the community reintegration process and the acquisition of functional skills for the newly disabled warrant further study. The long-term impact of sports involvement on prevention of cardiovascular disease, obesity, and other associated risks of a sedentary existence demands attention in our aging SCI population.

Activities of Daily Living↗
PubMed1985

Lactate provocation of panic attacks. II. Biochemical and physiological findings.

Thirty-one of 43 patients with panic disorder or agoraphobia with panic attacks and none of 20 normal controls panicked in response to infusions of sodium lactate. Before receiving lactate, patients showed higher heart rates than controls and also signs of hyperventilation. During lactate infusion, patients who did not panic, nevertheless, developed higher lactate and pyruvate levels and greater ionized calcium and pH changes than controls. Lactate-induced panic attacks were regularly accompanied by biological changes consistent with hyperventilation and central noradrenergic activation and irregularly by elevation of plasma norepinephrine and cortisol levels. Panic attacks were not associated with changes in epinephrine or calcium levels or pH. Baseline arousal increased the likelihood of panic during lactate infusion. It is hypothesized that lactate-induced panic primarily involves central noradrenergic discharge with inconsistent peripheral manifestations.

Adult↗
PubMed1985

Lactate infusions in obsessive-compulsive disorder.

Panic attacks followed sodium lactate infusions in one of seven patients with obsessive-compulsive disorder and 26 of 48 patients with panic disorder or agoraphobia with panic attacks. This suggests that lactate-induced panic is specific to the latter groups.

Adult↗
PubMed1985

Specificity of lactate infusions in social phobia versus panic disorders.

Lactate infusions produced panic attacks in one of 15 patients with social phobia, four of nine with agoraphobia, and 10 of 20 with panic disorder in a blind study. The proportion of patients with social phobia who panicked in response to lactate was significantly lower than that of patients with agoraphobia or panic disorder. These findings lend validity to the DSM-III classification of anxiety states. They also suggest that the pathophysiology of social phobia differs from that of disorders characterized by spontaneous panic attacks.

Adult↗
PubMed1984

Lactate provocation of panic attacks. I. Clinical and behavioral findings.

To assess the pharmacologic and phenomenologic comparability of lactate-induced and naturally occurring panic attacks, patients meeting DSM-III criteria for panic disorder or agoraphobia with panic attacks were infused with 0.5M racemic sodium lactate before and after successful drug treatment. Lactate-induced and naturally occurring panic attacks were symptomatically similar. Following treatment, the patients' response to lactate did not differ from that of normal controls, whereas the pretreatment panic rate was much higher. These data suggest that lactate acts, by as yet unidentified mechanisms, to trigger the same panic attacks as occur spontaneously in vulnerable persons.

Adult↗
PubMed1980

Surface morphology of isolated cardiac myocytes from hypertrophied hearts of aging spontaneously hypertensive rats.

Morphologic features of the cell surface were studied in isolated cardiac myocytes obtained from 12 and 48 week old Spontaneously Hypertensive Rats (SHR) and normotensive Wistar-Kyoto (WKY) control rats. Hearts obtained from ether-anesthetized animals were perfused with Ca++-free Hanks' solution containing EGTA and 0.1% collagenase. The hearts were minced and the suspended cells fixed in 2% phosphate buffered glutaraldehyde. Cells mounted on Nuclepore membrane filters were dehydrated in alcohol and critical point dried for SEM. Quantitative evaluation of myocyte length, width and volume was done with a sonic digitizer on H and E stained cells by light microscopy. At both ages studied there was a significant increase in heart weight to body weight ratio, systolic blood pressure and cell size in SHR compared to WKY controls. In the older animals there appeared to be increased numbers of cell junction areas and deep grooves in the cell surface which appeared more pronounced in SHR than in WKY. The cell surface of the myocytes from 48 week old animals had deep capillary grooves surrounded by protruding longitudinal bundles of myofibrils. These changes would result in increased surface area of the larger cells and diminish the effect of increased cell size on diffusion distance from capillary to tissue. These changes in cell morphology were interpreted as providing a protective effect against development of functional impairment in the hypertrophied hearts.

Animals↗