Citations

Nimodipine is known to improve postischemic cerebral blood flow (CBF) and neurologic outcome in experimental animals. Whether or not the two observations are related is unknown. This study searched for a possible improved rate of brain metabolic recovery in animals treated with nimodipine postischemia. Complete cerebral ischemia was produced for 11 min in 16 dogs, followed by reperfusion for 70 min. Prior to ischemia, glucose was administered (0.75 g · kg −1 ) in 12 dogs. Half of the glucose-treated dogs were given i.v. nimodipine, beginning 5 min postischemia (10 μg · kg −1 bolus followed by 1 μg · kg −1 · min −1 ). The other half were given only saline postischemia. The remaining four dogs were given no glucose and received saline only postischemia. In all dogs, serial brain biopsies were taken at 2, 20, 40, and 70 min postischemia. In 5 dogs, the integrity of the blood–brain barrier (BBB) was tested by injection of Evans blue dye and postmortem examination of the brains. Brain biopsies were assayed for concentrations of phosphocreatine, ATP, ADP, AMP, glucose, lactate, and pyruvate. In all dogs, there was rapid restoration of a normal brain energy state following reperfusion. Brain lactate had returned to near normal in all dogs by 70 min postischemia, and the rate of lactate depletion was not different between groups. The integrity of the BBB was only minimally affected. A portion of the brain lactate was converted to pyruvate rather than crossing the BBB. If lactate is a valid marker of the washout of metabolic products postischemia, there is no apparent benefit resulting from a nimodipine-induced increase in CBF during the initial 70 min following ischemia.

Regional cerebral ischemia was produced in the rabbit by unilateral transorbital occlusion of the middle cerebral artery (procedure I); the middle cerebral and azygos anterior cerebral or anterior communicating artery (procedure II); or the middle cerebral, azygos anterior cerebral or anterior communicating, and internal carotid artery (procedure III). Evolution of ischemic lesions was examined with the immunohistochemical reaction for tubulin. With procedure I, ischemic lesions did not become constantly visible for 6 h in the basal ganglia and for 8 h in the frontoparietal region of the cerebral cortex. With procedure II, it was shortened to 3 h in the basal ganglia and to 6 h in the cerebral cortex. With procedure III, the ischemic lesions were observed in 1 h both in the basal ganglia and in the cerebral cortex as loss of the reaction for tubulin in the neuropil, nerve cell bodies, and dendrites. The evidence of neuronal damage became apparent in the same areas later by staining with hematoxylin–eosin. The experimental model presented here may be suitable for investigation of the mechanism that shifts reversible ischemia to cerebral infarction and for evaluation of the effectiveness of pharmacological intervention.

Intracellular brain pH and indicator tissue perfusion were measured with a lipid-soluble, pH-sensitive fluorescent indicator in 10 rabbits who had either severe or moderate focal ischemia depending on whether the middle cerebral artery was occluded at its main trunk or bifurcation. Preocclusion tissue indicator perfusion was 50.1 ml/100 g/min and intracellular brain pH was 7.03. In severe focal ischemia, immediate postocclusion tissue perfusion was 12.7 ml/100 g/min and intracellular brain pH was 6.64. Four hours after occlusion, the perfusion was 5.2 ml/100 g/min and intracellular brain pH was 6.08. There was EEG and histological confirmation of infarction. In the moderate focal ischemia group, immediate postocclusion flow was 20.0 ml/100 g/min and intracellular brain pH was 6.92. At 3 h, postocclusion tissue perfusion was 22.6 ml/100 g/min and intracellular brain pH was 6.86. Therefore, for the first 3 h, this ischemic penumbra was stable. At the fourth hour, both cerebral tissue perfusion and intracellular brain pH worsened. This suggests that the ischemic penumbra is a dynamic state. The rabbit is a good experimental model for the production of both severe and moderate focal ischemia.

Ten minutes of complete cerebral ischemia was produced in 26 dogs by temporary ligation of the aorta and the venae cavae. Twenty dogs received nimodipine, a calcium entry blocker, 10 μg kg −1 i. v. 2 min after the ischemic period, followed by 1 μg kg −1 min −1 for 2–3 h. Six dogs received only the solvent used for nimodipine. Fourteen dogs received nimodipine for 3 h and were subsequently evaluated neurologically up to 48 h postischemia. In the 12 other dogs, CBF and metabolism were followed for 2 h postischemia while either nimodipine or the solvent only was infused. The results were compared to previously published results for untreated dogs and dogs given nimodipine before the ischemic event. Nimodipine had the same effect on postischemic CBF whether started before or after the ischemic event, nearly doubling the flow when compared with untreated controls, whereas the solvent alone caused only a slight increase in CBF over control. By contrast, nimodipine initiated in the preischemic period significantly improved the neurologic outcome, but when initiated in the post-ischemic period the results were equivocal, such that the outcome was not significantly different from either the untreated group or the group in which nimodipine was initiated preischemia. Metabolic measurements did not give any indication of a specific effect of nimodipine, nor could the metabolic results be used as an indicator of neurologic outcome. The results are consistent with a beneficial effect of nimodipine following complete cerebral ischemia; however, evaluation of neurologic functional effects will require a more sensitive model.

Intracellular brain pH was measured with a lipid-soluble, pH-sensitive fluorescent indicator in 16 squirrel monkeys. Eight of these were under halothane anesthesia and eight under barbiturate anesthesia. Measurements were taken before, during, and after focal incomplete ischemia. Brain pH following 3 h of cerebral focal ischemia changed from a normal value of 7.0 to 6.5 and 6.2 in animals studied under barbiturate and halothane anesthesia, respectively. Brain pH returned toward normal after flow was restored in animals under barbiturate anesthesia but continued to deteriorate in animals under halothane anesthesia.

There are conflicting reports regarding the effects of hypoxemia on the cerebral metabolic rate for oxygen (CMRO 2 ). Accordingly, we examined the changes in CMRO 2 during normoxia, progressive hypoxia (P a O 2 of 37, 27, and 23 mm Hg), and normoxic recovery from hypoxia, Measurements were made in dogs anesthetized with nitrous oxide (60–70%) and halothane (<0.1%) in oxygen. Arterial-cerebral venous blood oxygen content differences and cerebral blood flow (CBF) were measured simultaneously, the latter by a technique (collection of sagittal sinus outflow) previously validated for conditions of near-maximal CBF, The duration of each of the three hypoxic exposures was approximately 10 min. CMRO 2 was significantly decreased (14%) only when the arterial blood oxygen tension was reduced to 23 mm Hg. CBF increased progressively to a maximum of 153% of control. Posthypoxemic brain biopsy values for cerebral metabolites obtained 40 min after normoxemia had been restored were normal. These results, in conjunction with an unchanged CMRO 2 at 40 min normoxic recovery, suggest that no gross irreversible brain cell damage occurred. We conclude that with progressive hypoxemia. CMRO 2 remains stable until oxygen demand exceeds oxygen delivery, resulting there after in a progressive reduction in CMRO 2 .

Abstract Earlier, we demonstrated the essential role of Kruppel-like transcription factor, TIEG1, in TGF-β–induced regulatory T cell (Treg) development. In this article, we demonstrate that IL-6, which promotes Th17 development, abrogated TIEG1 nuclear translocation and inhibited TGF-β–induced Treg development. Tyrosine kinase Tyk2-mediated phosphorylation of TIEG1 at Tyr179 promoted noncanonical K-27–linked polyubiquitination, which inhibited TIEG1 nuclear translocation. To test the role of TIEG1-regulated Treg/Th17 development in antitumor immunity, we analyzed TRAMP-C2 tumor growth in TIEG1−/− mice. The defective Treg development and elevated Th17 response resulted in enhanced immune reactivity in the tumor and inhibition of TRAMP-C2 tumor growth in TIEG1−/− mice. Thus, our results uncovered a novel regulatory mechanism that modulates Tregs and may regulate tumor progression.

The goal of health care is to provide high-quality care at an affordable cost for its patients. However, the population it serves has changed dramatically since the popularization of hospital-based health care. With available new technology, alternative health care delivery methods can be designed and tested. This study examines scalable office-based health care for small business, where health care is delivered to the office floor. This delivery was tested in 18 individuals at a small business in Minneapolis, Minnesota. The goal was to deliver modular health care and mitigate conditions such as diabetes, hyperlipidaemia, obesity, sedentariness and metabolic disease. The modular health care system was welcomed by employees – 70% of those eligible enrolled. The findings showed that the modular health care deliverable was feasible and effective. The data demonstrated significant improvements in weight loss, fat loss and blood variables for at risk participants. This study leaves room for improvement and further innovation. Expansion to include offerings such as physicals, diabetes management, smoking cessation and prenatal treatment would improve its utility. Future studies could include testing the adaptability of delivery method, as it should adapt to reach rural and under-served populations.

To test the postulate that sex difference, sex steroids, and peptidyl secretagogues control GH autofeedback, 11 healthy postmenopausal women and 14 older men were each given 1) a single iv pulse of GH to enforce negative feedback and 2) continuous iv infusion of saline vs. combined GHRH/GHRP-2 to drive feedback escape during pharmacological estradiol (E2; women) or testosterone (T; men) supplementation vs. placebo in a double-blind, prospectively randomized crossover design. By three-way ANCOVA, sex difference, sex hormone treatment, peptide stimulation, and placebo/saline responses (covariate) controlled total (integrated) GH recovery during feedback (each P < 0.001). Both sex steroid milieu ( P = 0.019) and dual-peptide stimulation ( P < 0.001) determined nadir (maximally feedback-suppressed) GH concentrations. E2/T exposure elevated nadir GH concentrations during saline infusion ( P = 0.003), whereas dual-peptide infusion did so independently of T/E2 and sex difference ( P = 0.001). All three of sex difference ( P = 0.001), sex steroid treatment ( P = 0.005), and double-peptide stimulation ( P < 0.001) augmented recovery of peak (maximally feedback-escaped) GH concentrations. Peak GH responses to dual-peptidyl agonists were greater in women than in men ( P = 0.016). E2/T augmented peak GH recovery during saline infusion ( P < 0.001). Approximate entropy analysis corroborated independent effects of sex steroid treatment ( P = 0.012) and peptide infusion ( P < 0.001) on GH regularity. In summary, sex difference, sex steroid supplementation, and combined peptide drive influence nadir, peak, and entropic measurements of GH release under controlled negative feedback. To the degree that the pharmacological sex steroid, GH, and dual-peptide clamps provide prephysiological regulatory insights, these outcomes suggest major determinants of pulsatile GH secretion in the feedback domain.