Best anesthetics for assessing left ventricular systolic function by echocardiography in mice.

Our review of the literature of the major cardiovascular journals for the past three years showed that for all studies using anesthesia for mouse echocardiography, the predominant anesthetic was isoflurane, which was used in 76% of the studies. The goal of this investigation was to determine if isoflurane is indeed the best anesthetic. Accordingly, we compared isoflurane with 2,2,2-tribromoethanol (Avertin), ketamine-xylazine, and ketamine on different days in the same 14 mice, also studied in the conscious state without anesthesia. A randomized crossover study design was employed to compare the effects on left ventricular (LV) systolic function and heart rate of the four different anesthetic agents assessed by transthoracic echocardiography. As expected, each anesthetic depressed LV ejection fraction and heart rate when compared with values in conscious mice. Surprisingly, isoflurane was not the best, but actually second to last in maintaining normal LV function and heart rate. The anesthetic with the least effect on LV function and heart rate was ketamine alone at a dose of 150 mg/kg, followed by Avertin at 290 mg/kg, isoflurane at 3% induction and 1 to 2% maintenance, and lastly ketamine-xylazine at 100 and 10 mg/kg, respectively. In summary, these results indicate that ketamine alone exerts the least depressant effects on LV function and heart rate, with Avertin second, suggesting that these anesthetics should be used when it is not feasible to study the animals in the conscious state as opposed to the most commonly used anesthetic, isoflurane.

Cocaine is pharmacologically active in the nonhuman primate fetal brain.

Cocaine use during pregnancy is deleterious to the newborn child, in part via its disruption of placental blood flow. However, the extent to which cocaine can affect the function of the fetal primate brain is still an unresolved question. Here we used PET and MRI and show that in third-trimester pregnant nonhuman primates, cocaine at doses typically used by drug abusers significantly increased brain glucose metabolism to the same extent in the mother as in the fetus (approximately 100%). Inasmuch as brain glucose metabolism is a sensitive marker of brain function, the current findings provide evidence that cocaine use by a pregnant mother will also affect the function of the fetal brain. We are also unique in showing that cocaine's effects in brain glucose metabolism differed in pregnant (increased) and nonpregnant (decreased) animals, which suggests that the psychoactive effects of cocaine are influenced by the state of pregnancy. Our findings have clinical implications because they imply that the adverse effects of prenatal cocaine exposure to the newborn child include not only cocaine's deleterious effects to the placental circulation, but also cocaine's direct pharmacological effect to the developing fetal brain.

Left ventricular systolic and diastolic function in healthy adult bonnet macaques (Macaca radiata). New echocardiographic indices in Old World monkeys.

OBJECTIVES: Macaques are used in cardiovascular and metabolic research. We determined echocardiographic-derived reference values of left ventricular (LV) systolic and diastolic function in healthy adult bonnet macaques (Macaca radiata). METHODS: Transthoracic echocardiography was performed during ketamine sedation in 83 (67% female) healthy monkeys (age 7-26 years). RESULTS: Technically adequate studies were obtained in all subjects and required 10.1 +/- 1.3 min of scanning time. Age correlated inversely with the following Doppler indices: E (r = -0.44, p < 0.001), E/A (r = -0.26, p = 0.02), E' (r = -0.45, p < 0.001, E'/A' (r = -0.44, p < 0.001), E/E' (r -0.25, p = 0.03), S' (r = -0.33, p = 0.003), Vp (r = -0.26, p = 0.049). LV mass was more strongly correlated with crown rump length (r = 0.72, p < 0.001) and body surface area (r = 0.70, p < 0.001) than with body mass index (r = 0.47, p < 0.001) and weight (r = 0.63, p < 0.001). CONCLUSIONS: This study demonstrates echocardiography is feasible for characterizing LV function. Age-related changes in Doppler indices in primates are similar to those in humans. LV mass is more closely related to fat-free mass indices. We provide reference values for LV systolic and diastolic function in adult bonnet macaques across the captive life span.

Antidepressant-induced neurogenesis in the hippocampus of adult nonhuman primates.

New neurons are generated in the adult hippocampus of many species including rodents, monkeys, and humans. Conditions associated with major depression, such as social stress, suppress hippocampal neurogenesis in rodents and primates. In contrast, all classes of antidepressants stimulate neuronal generation, and the behavioral effects of these medications are abolished when neurogenesis is blocked. These findings generated the hypothesis that induction of neurogenesis is a necessary component in the mechanism of action of antidepressant treatments. To date, the effects of antidepressants on newborn neurons have been reported only in rodents and tree shrews. This study examines whether neurogenesis is increased in nonhuman primates after antidepressant treatment. Adult monkeys received repeated electroconvulsive shock (ECS), which is the animal analog of electroconvulsive therapy (ECT), the most effective short-term antidepressant. Compared with control conditions, ECS robustly increased precursor cell proliferation in the subgranular zone (SGZ) of the dentate gyrus in the monkey hippocampus. A majority of these precursors differentiated into neurons or endothelial cells, while a few matured into glial cells. The ECS-mediated induction of cell proliferation and neurogenesis was accompanied by increased immunoreactivity for the neuroprotective gene product BCL2 (B cell chronic lymphocytic lymphoma 2) in the SGZ. The ECS interventions were not accompanied by increased hippocampal cell death or injury. This study demonstrates that ECS is capable of inducing neurogenesis in the nonhuman primate hippocampus and supports the possibility that antidepressant interventions produce similar alterations in the human brain.

Effects of Acute Confinement Stress-induced Hypothalamic-Pituitary Adrenal Axis Activation and Concomitant Peripheral and Central Transforming Growth Factor-ß1 Measures in Nonhuman Primates.

Transforming growth factor-ß1 (TGF-ß1) is a multifunctional cytokine with anti-inflammatory, immunosuppressive and neuroprotective properties. The hypothalamic-pituitary-adrenal (HPA) axis and immune system exert bidirectional influences on each other, via cortisol and TGF-ß1, but the exact nature of the interaction is not well characterized. The current study examined the effects, in bonnet macaques (Macaca radiata), of two consecutive acute confinement stress periods in an unfamiliar room while mildly restrained, first without and then with dexamethasone pretreatment (0.01 mg/kg IM). Preceding the confinement studies, a non-stress control condition obtained contemporaneous levels of cortisol and TGF-ß1 in both plasma and cerebrospinal fluid (CSF) to match the confinement stress studies. Subjects were reared under either normative or variable foraging demand (VFD) conditions. Since there were no rearing effects at baseline or for any of the conditions tested -- either for cortisol or TGF-ß -- the study analyses were conducted on the combined rearing groups. The stress condition increased both plasma and CSF cortisol levels whereas dexamethasone pretreatment decreased cortisol concentrations to below baseline levels despite stress. The stress condition decreased TGF-ß1 concentrations only in CSF but not in serum. Together the data suggested that stress-induced reductions of a centrally active neuroprotective cytokine occurs in the face of HPA axis activation, potentially facilitating glucocortoid-induced neurotoxicity. Stress-induced reductions of neuroprotective cytokines prompts exploration of protective measures against glucocorticoid-induced neurotoxicity.

Maternal and fetal 11C-cocaine uptake and kinetics measured in vivo by combined PET and MRI in pregnant nonhuman primates.

UNLABELLED: Cocaine use during pregnancy has been shown to be deleterious to the infant. This may reflect reduction of flow to placenta or effects on the fetal brain. Methods to assess pharmacokinetics of drugs of abuse in vivo would be useful to investigate the mechanisms underlying the fetal adverse effects. We recently reported that combined MRI and PET technology allows the measurement of radioisotope distribution in maternal and fetal organs in pregnant Macaca radiata. Here, we evaluate the utility of PET to measure the uptake and distribution of (11)C-cocaine in the third-trimester fetus. METHODS: Six pregnant M. radiata weighing 3.8-9.0 kg were anesthetized and MR images were acquired on a 4-T MRI instrument. In all 6 animals, dynamic PET scans were subsequently acquired using 148-259 MBq of (11)C-cocaine. Time-activity curves for both maternal and fetal organs were obtained simultaneously with the pregnant animal positioned transverse in the PET scanner. Distribution volume ratios for maternal and fetal brain for (11)C-cocaine were calculated. RESULTS: Coregistration of PET and MR images allowed identification of fetal organs and brain regions and demonstrated that (11)C-cocaine or its labeled metabolites readily cross the placenta and accumulate mainly in fetal liver and to a lesser extent in the brain. Time to reach peak (11)C uptake in brain was shorter for the mother than for the fetus. The distribution volume ratios of the maternal striatum were higher than those of the fetus. Placenta was clearly visible on the early time frames and showed more rapid uptake and clearance than other fetal tissues. CONCLUSION: The pregnant M. radiata model allows the noninvasive measurement of radioisotope pharmacokinetics in maternal and fetal brain and other organs simultaneously. Although the uptake of radioactivity into the fetal brain after the injection of (11)C-cocaine is lower and slower than in the maternal brain, a measurable quantity of (11)C-cocaine (or its labeled metabolites) accumulates in the fetal brain at early times after injection. The highest accumulation of (11)C occurs in the fetal liver. Rapid radioisotope accumulation and clearance in the placenta offer potential as an input function for kinetic modeling for future studies of binding site availability.

Maternal-fetal in vivo imaging: a combined PET and MRI study.

UNLABELLED: An understanding of how drugs are transferred between mother and fetus during the gestational period is an important medical issue of relevance to both therapeutic drugs and drugs of abuse. Though there are several in vitro and in vivo methods to examine this issue, all have limitations. Furthermore, ethical and safety considerations generally preclude such studies in pregnant humans. PET and appropriately labeled compounds have the ability to provide information on both maternal-fetal drug pharmacokinetics and pharmacodynamics. We present here a nonhuman primate animal model and the methodology for combining PET and MRI to identify fetal organs and to measure maternal and fetal isotope distribution using (18)F-FDG and a whole-body imaging protocol to demonstrate proof-of-principle. METHODS: One nonpregnant nonhuman primate was used for determination of the anesthesia protocol and MRI methods and 3 pregnant nonhuman primates (Macaques radiata) weighing 4.5-7 kg were used for the imaging study and anesthetized with propofol (160-300 micro g/kg/min). Anatomic T2-weighted MR images were acquired on a 4-T MR instrument. Subsequently, whole-body PET images were acquired 35 min after injection of (18)F-FDG, and standardized uptake values (SUVs) were calculated. Image processing and coregistration were performed using commercial software. RESULTS: All animals underwent uneventful general anesthesia for a period of up to 7 h. Coregistration of PET and MR images allowed identification of fetal organs and demonstrated that (18)F-FDG readily crosses the placenta and that (18)F accumulates in both maternal and fetal brain, heart, and bladder. Brain SUVs averaged 1.95 +/- 0.08 (mean +/- SD) and 1.58 +/- 0.11 for mothers and fetuses, respectively. Monkeys delivered healthy babies after a normal gestational term of 170 d following the PET/MRI study. CONCLUSION: The pregnant macaque in combination with PET and MRI technology allows the measurement of radioisotope distribution in maternal and fetal organs. This demonstrates the potential for noninvasively measuring the transfer of drugs across the placenta and for measuring the fetal drug distribution. It also opens up the possibility for studying binding and elimination as well as the effects of a drug on specific cellular elements and physiologic processes during the gestational period in a primate model.

Differing concentrations of corticotropin-releasing factor and oxytocin in the cerebrospinal fluid of bonnet and pigtail macaques.

The two neuropeptides corticotropin-releasing-factor (CRF) and oxytocin (OT) may produce opposing behavioral effects - elevations of the former have been associated with anxiety and social vigilance and reductions of the latter with reduced social affiliation. We sought to test the hypothesis that, within the primate macaque genus, the more gregarious, affiliative, and affectively stable bonnet species (Macaca radiata) would exhibit lower cerebrospinal fluid (CSF) CRF and higher CSF OT concentrations in comparison to its close relative, the temperamentally volatile and socially distant pigtail (Macaca nemestrina). Cisternal CSF samples were obtained from young adult male and female pigtail and bonnet macaques, and CRF and OT concentrations were measured by radioimmunoassay. Pigtail macaques exhibited significantly higher concentrations of CSF CRF and significant lower concentrations of CSF OT than bonnet macaques. Results were not attributable to age or sex differences in group composition. When included together in a multiple regression, CRF and OT showed a multiple R of 0.76, accounting for more than half of the species variance. Although species differences in the bioeffectiveness of these peptides may possibly confound the observed biobehavioral relationships, in the absence of any existing data to that effect, the current findings appear in accordance with the hypothesis and consistent with previously reported species-typical behaviors observed in these macaques.

Percutaneous transcricoid jet ventilation compared with surgical cricothyroidotomy in a sheep airway salvage model.

BACKGROUND: We developed a large animal model of the "cannot intubate/cannot ventilate" (CNI/V) scenario to compare percutaneous transcricoid manual jet ventilation (MJV) with surgical cricothyroidotomy (SC). METHODS: Twelve sheep weighing 40-80 kg were assigned to MJV or SC groups. After sedation, intubation, and line placement, CNI/V was simulated by removing the tracheal tube and inducing paralysis with vecuronium. When SaO2 reached 80% (t=0), MJV catheter insertion or SC was initiated. Upon successful airway placement, ventilation began using 100% oxygen at 20 breaths/min. MJV was administered at 50 psi. HR, BP, SaO2, pH, PCO2, and PO2 were recorded at t=0, 30, 60, 90, 120, 150, 180, 300, 600, and 1200 s. Data were reported as mean+/-S.E.M. over the whole observation period. Baseline values were compared using Student's t-tests. Repeated-values ANOVA was used for post-procedure group comparisons. Statistical tests were two-tailed and alpha was set at 0.05. RESULTS: Body weights were not significantly (P=0.08) different between MJV (65+/-6 kg) and SC (52+/-3 kg) groups. Baseline respiratory and hemodynamic variables were also not significantly different. Median procedure time for MJV (20 s) and SC (24 s) was not significantly (P=0.69) different. Post-procedure values were not significantly different for SaO2 (P=0.65), pH (P=0.70), PCO2 (P=0.47), PO2 (P=0.84), MAP (P=0.09), or HR (P=0.16) over the entire 20 min resuscitation period. CONCLUSION: Using a realistic model of CNI/V we found no difference in respiratory or hemodynamic variables between MJV and SC. Adequate ventilation and perfusion was maintained solely by MJV for up to 20 min.

Lethargy, ulcers, bronchopneumonia and death in two aged female bonnet macaques presumed to be caused by Cercopithicine herpes virus I.

Over the course of 4 weeks, two female aged bonnet macaque (Macaca radiata) group-housed females died after the dominant male was removed from the group and the newly dominant male persistently chased, caught and bred all females in the pen. The two aged affected females were observed exhibiting lethargy, dyspnea, with widespread necroulcerative lesions in and around the mouth, muzzle and bridge of their noses. Extensive ulcerative glossitis, necrotic bronchopneumonia with intra-nuclear inclusions and the absence of other evidence is highly suggestive that death was caused by an alphaherpes virus commonly known as herpes B virus. Herpes B virus is a potentially zoonotic disease periodically shed by macaques, which is structurally related to herpes simplex viruses I and II of humans. The emergence of fatal B virus to primates in this pen may have been associated with the combination of age and stress in the affected individuals.

PNC-28, a p53-derived peptide that is cytotoxic to cancer cells, blocks pancreatic cancer cell growth in vivo.

PNC-28 is a p53 peptide from its mdm-2-binding domain (residues 17-26), which contains the penetratin sequence enabling cell penetration on its carboxyl terminal end. We have found that this peptide induces necrosis, but not apoptosis, of a variety of human tumor cell lines, including several with homozygous deletion of p53, and a ras-transformed rat acinar pancreatic carcinoma cell line, BMRPA1. Tuc3. On the other hand, PNC-28 has no effect on untransformed cells, such as rat pancreatic acinar cells, BMRPA1, and human breast epithelial cells and no effect on the differentiation of human stem cells. In this study, we now test PNC-28 in vivo for its ability to block the growth of BMRPA1. Tuc3 cells. When administered over a 2-week period in the peritoneal cavities of nude mice containing simultaneously transplanted tumors, PNC-28 causes complete destruction of these tumors. When delivered concurrently with tumor explantation at a remote site, PNC-28 causes a complete blockade of any tumor growth during its 2-week period of administration and 2 weeks posttreatment, followed by weak tumor growth that plateaus at low tumor sizes compared with tumor growth in the presence of a control peptide. When administered after tumor growth has occurred at a site remote from the tumor, PNC-28 causes a decrease in tumor size followed by a slow increase in tumor growth that is significantly slower than growth in the presence of control peptide. These results suggest that PNC-28 may be effective in treating cancers especially if delivered directly to the tumor.

Cerebrospinal fluid concentrations of biogenic amines and corticotropin-releasing factor in adolescent non-human primates as a function of the timing of adverse early rearing.

Adolescent bonnet macaques nursed as infants by mothers facing unpredictable requirements for food procurement (variable foraging demand, VFD) display persistent neurobiological disturbances. This study examined the long-term neurochemical and behavioral effects of adverse rearing initiated later in infancy than in previous cohorts of subjects to test the hypothesis that the timing of an early adverse experience would influence patterns of biobehavioral outcome. Cisternal cerebrospinal fluid (CSF) monoamine and corticotropin-releasing factor (CRF) concentrations were obtained from 20 bonnet macaques (11 VFD-reared and 9 normally reared controls) approximately 2 years after the end of differential rearing. VFD-reared primates displayed on multiple samplings significantly lower CSF CRF concentrations and higher CSF 5-hydroxyindoleacetic acid (5-HIAA) concentration compared to controls. In the VFD-reared, significant inverse correlations between CRF and all three monoamines were found (5-HIAA, 3-methoxy-4-hydroxyphenethyleneglycol and homovanillic acid), most prominently for 5-HIAA. In controls, but not VFD-reared subjects, CSF CRF was positively correlated with changes in "gregariousness" upon presentation of a fear stimulus. VFD-reared subjects displayed greater baseline hierarchical engagement than controls. In contrast to prior findings, in which rearing under VFD conditions at an earlier age led to increased CSF CRF compared with controls, CSF CRF was lower after later exposure to VFD rearing than in controls. Thus, the timing of exposure to VFD conditions early in life evidently determines whether CSF CRF was found to be elevated or decreased, within the context of increased serotonin metabolism, during the course of primate maturation.