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T McAuliffe

Publications and source records attributed to T McAuliffe.

6 recordsLinked to original sources
PubMed1991

The role of neutrophils and platelets in a rabbit model of thromboembolic stroke.

Cerebral ischemia is accompanied by many of the cardinal features of acute inflammation such as neutrophil and platelet activation and accumulation. We sought to determine whether circulating neutrophils or platelets contribute to brain injury in a rabbit model of thromboembolic stroke that includes a fixed duration of superimposed systemic hypotension. We randomized 18 rabbits to receive either antineutrophil antiserum (n = 6), antiplatelet antiserum (n = 5), or nonimmune serum (n = 7). We assessed brain ischemia by measuring cerebral blood flow, intracranial pressure, and infarct size. Following the intracarotid administration of an autologous clot, cerebral blood flow in all groups fell to less than 5 ml/100 g/min during induced hypotension. After restoration of baseline blood pressure, mean cerebral blood flow in neutropenic animals recovered to 20-30 ml/100 g/min while that in control and thrombocytopenic rabbits remained at less than 10 ml/100 g/min. Intracranial pressure in control animals rose steadily to a final value of 241% of baseline, while a much smaller increase (148% of baseline) was noted in the thrombocytopenic group; no change from baseline was evident in the neutropenic group. Infarct size was significantly (p less than 0.05) reduced in the neutropenic group but not in the thrombocytopenic group. These results suggest that neutrophils may be important contributors to ischemia-induced brain injury whereas the role of platelets is more subtle.

Animals↗
PubMed1990

Effects of age and level of physical activity on plasma norepinephrine kinetics.

We examined the effects of age and physical activity on plasma norepinephrine (NE) kinetics in active and inactive older and younger men. NE kinetics were estimated by calculation of the rates of NE appearance and clearance during infusion of tritiated norepinephrine [( 3H]-NE). Older active men had the highest level of plasma NE (pg/ml) and NE appearance (microgram.min-1.FFW-1, where FFW is fat-free weight) relative to younger men and inactive older men. NE clearance (l.min-1.FFW-1) was not influenced by age or physical activity. No significant associations were noted between percent body fat, supine blood pressure with resting levels of NE, NE appearance, and NE clearance. We concluded that 1) chronic participation in physical activity by older men, but not younger men, is associated with higher resting levels of plasma NE and NE appearance and 2) the degree of adiposity does not influence plasma NE kinetics in healthy younger and older men. The level of physical activity is an influencing factor on plasma NE and NE appearance into circulation in healthy older men.

Adult↗
PubMed1990

Tissue plasminogen activator reduces brain injury in a rabbit model of thromboembolic stroke.

Tissue plasminogen activator is an endogenous fibrin-specific serine protease with potent thrombolytic activity. We investigated the efficacy of tissue plasminogen activator in reducing cerebral infarct size after thromboembolic stroke in a rabbit model. Seventeen rabbits were randomized to receive either tissue plasminogen activator (2.5 mg/kg, n = 6) or vehicle control (n = 11). We controlled mean arterial pressure, hematocrit, and arterial blood gases before and after the intracarotid embolization of an autologous clot. Cerebral blood flow (cm3/100 g/min) (mean +/- SEM) was immediately reduced from 55.2 +/- 7.7 to 8.5 +/- 2.5 in the control group and from 61.8 +/- 14.8 to 10.0 +/- 3.5 in the treated group after embolization. Cerebral blood flow recovered significantly within 60 minutes of thrombolytic therapy and attained a value of 59.6 +/- 10.0 cm3/100 g/min 4 hours after embolization, whereas cerebral blood flow in control animals demonstrated only a minimal recovery to 15.3 +/- 8.9 cm3/100 g/min. Cerebral infarct size (percent of hemisphere) was reduced from 34.4 +/- 5.6% in control animals to 8.8 +/- 5.6% in treated animals (mean +/- SEM, p less than 0.01). These results suggest that tissue plasminogen activator may be efficacious in restoring cerebral blood flow and thus limiting infarct size in acute thromboembolic stroke.

Animals↗
PubMed1990

The 24-hour pattern of the levels of serum progesterone and immunoreactive human chorionic gonadotropin in normal early pregnancy.

The purpose of this study was to characterize the levels of progesterone and hCG and the variability of those levels over 24 h in early pregnancy. Venous blood sampling was performed every 30 min during the first trimester of a subsequently normal pregnancy in 19 women. The variability in each progesterone and hCG data series was evaluated by three methods: 1) comparing the coefficient of variation (CV) of each individual hormone data set to the respective assay CV, 2) examining each data set for pulses, and 3) relating changes in hormone levels to the ingestion of a meal. The CV for each individual progesterone data set was greater than the assay CV (CV progesterone, 3.7%) in all subjects (range, 5.58-21.90%). The CV for each individual hCG data set was greater than the assay CV for hCG (CV hCG, 4.3%) in 17 of 19 subjects (range, 3.27-10.95%). Mean (+/- SE) progesterone and hCG peak frequencies were 2.4 +/- 0.3 and 1.7 +/- 0.3/24 h, respectively. When postprandial levels of progesterone were normalized to a percentage of preprandial levels, there were maximum decreases in mean progesterone levels of 15.4 +/- 2.6% and 13.1 +/- 1.9% 1 h after initiation of the lunch and dinner meals, respectively (P less than 0.05). Postprandial hCG levels decreased by 2.3 +/- 1.9% and 0.4 +/- 1.6% during this same time period (P greater than 0.05). These findings suggest that 1) both progesterone and hCG levels fluctuate during a 24-h period in early pregnancy; 2) this variability of both hormones is greater than inherent assay variability and can be resolved into a short term pattern of pulses, suggesting alterations in episodic secretion, metabolic clearance, or volume of distribution of the hormone; and 3) a portion of the variability in the progesterone time set may be due to the ingestion of meals.

Adult↗
PubMedDate not supplied

The precision and accuracy of a portable heart rate monitor.

A device that would comfortably and accurately measure exercise heart rate during field performance could be valuable for athletes, fitness participants, and investigators in the field of exercise physiology. Such a device, a portable telemeterized microprocessor, was compared with direct EKG measurements in a laboratory setting under several conditions to assess its accuracy. Twenty-four subjects were studied at rest and during light-, moderate-, high-, and maximal-intensity endurance activities (walking, running, aerobic dancing, and Nordic Track simulated cross-country skiing. Differences between values obtained by the two measuring devices were not statistically significant, with correlation coefficient (r) values ranging from 0.998 to 0.999. The two methods proved equally reliable for measuring heart rate in a host of varied aerobic activities at varying intensities.

Adult↗