Plasma glucose levels and leverpress avoidance versus escape behaviors in rats.

The relationship between performance in an avoidance conditioning paradigm and the plasma glucose levels of Sprague-Dawley rats was examined in two experiments. In Experiment 1 we investigated whether glucose levels varied with the animal's relative success at acquiring the avoidance task. Results indicated that animals classified as avoiders (60% avoidance and above) had lower glucose levels than animals classified as escapers (30% avoidance and below). In Experiment 2 we looked at whether glucose levels showed within-subject changes with avoidance acquisition. Results demonstrated that glucose levels showed reductions if an animal learned the avoidance response. Subjects that did not learn the response showed no such reduction. Such results suggest that the physiological response to stress is attenuated by acquisition of successful coping behaviors that exercise control over the onset of aversive events.     

The rate of absorption and relative bioavailability of caffeine administered in chewing gum versus capsules to normal healthy volunteers

OBJECTIVE:The purpose of this study was to evaluate the rate of absorption and relative bioavailability of caffeine from a Stay Alert chewing gum and capsule formulation. METHODS: This was a double blind, parallel, randomized, seven treatment study. The treatment groups were: 50, 100, and 200 mg gum, 50, 100, and 200 mg capsule, and a placebo. Subjects consisted of 84 (n=12 per group); healthy, non-smoking, males who had abstained from caffeine ingestion for at least 20 h prior to dosing and were randomly assigned to the treatment groups. Blood samples were collected pre-dose and at 5, 15, 25, 35, 45, 55, 65, 90 min and 2, 3, 4, 6, 8, 12, 16 and 29 h post administration. Plasma caffeine levels were analyzed by a validated UV-HPLC method. RESULTS: Mean Tmax for the gum groups ranged from 44.2 to 80.4 min as compared with 84.0-120.0 min for the capsule groups. The Tmax, for the pooled data was significantly lower (P<0.05) for the gum groups as compared with the capsule groups. Differences in Tmax were significant for the 200 mg capsule versus 200 mg gum (P<0.05). The mean ka values for the gum group ranged from 3.21 to 3.96 h-1 and for the capsule groups ranged from 1.29 to 2.36 h-1. Relative bioavailability of the gum formulation after the 50, 100 and 200 mg dose was 64, 74 and 77%, respectively. When normalized to the total drug released from the gum (85%), the relative bioavailability of the 50, 100 and 200 mg dose were 75, 87, and 90%, respectively. No statistical differences were found for Cmax and AUCinf for comparisons of the gum and capsule formulations at each dose. Within each dose level, there were no significant formulation related differences in Cmax. No significant differences were observed in the elimination of caffeine after the gum or capsule. CONCLUSIONS: The results suggest that the rate of drug absorption from the gum formulation was significantly faster and may indicate absorption via the buccal mucosa. In addition, for the 100 and 200 mg groups, the gum and capsule formulations provide near comparable amounts of caffeine to the systemic circulation. These findings suggest that there may be an earlier onset of pharmacological effects of caffeine delivered as the gum formulation, which is advantageous in situations where the rapid reversal of alertness and performance deficits resulting from sleep loss is desirable.     

GFAP-expressing cells in the postnatal subventricular zone display a unique glial phenotype intermediate between radial glia and astrocytes

Neural stem cells in the adult subventricular zone (SVZ) derive from radial glia and express the astroglial marker glial fibrillary acidic protein (GFAP). Thus, they have been termed astrocytes. However, it remains unknown whether these GFAP-expressing cells express the functional features common to astrocytes. Using immunostaining and patch clamp recordings in acute slices from transgenic mice expressing green fluorescent protein (GFP) driven by the promoter of human GFAP, we show that GFAP-expressing cells in the postnatal SVZ display typical glial properties shared by astrocytes and prenatal radial glia such as lack of action potentials, hyperpolarized resting potentials, gap junction coupling, connexin 43 expression, hemichannels, a passive current profile, and functional glutamate transporters. GFAP-expressing cells express both GLAST and GLT-1 glutamate transporters but lack AMPA-type glutamate receptors as reported for dye-coupled astrocytes. However, they lack 100 microM Ba2+-sensitive inwardly rectifying K+ (K(IR)) currents expressed by astrocytes, but display delayed rectifying K+ currents and 1 mM Ba2+-sensitive K+ currents. These currents contribute to K+ transport at rest and maintain hyperpolarized resting potentials. GFAP-expressing cells stained positive for both K(IR)2.1 and K(IR)4.1 channels, two major K(IR) channels in astrocytes. Ependymal cells, which also derive from radial glia and express GFAP, display typical glial properties and K(IR) currents consistent with their postmitotic nature. Our results suggest that GFAP-expressing cells in concert with ependymal cells can perform typical astrocytic functions such as K+ and glutamate buffering in the postnatal SVZ but display a unique set of functional characteristics intermediate between astrocytes and radial glia.     

Takotsubo syndrome

The Takotsubo Syndrome was first described by Japanese investigators approximately 20 years ago and has been increasingly recognized in all countries. It occurs almost exclusively in postmenopausal women and is triggered by a severe emotional stress. Severe chest pain is common and the electrocardiogram often mimics that seen with an acute myocardial infarction. An echocardiogram or a left ventriculogram resembles a Takotsubo, a Japanese octopus fishing pot. In Japanese 'Takotsubo' means a 'fishing pot for trapping octopus.' These traps have a round bottom with a narrow neck. When the octopus enters the Takotsubo it is most often trapped while the fisherman pulls the device to the surface. The syndrome is reversible and over the next several weeks to months all electrocardiographic and echocardiographic changes revert to normal. It is likely that the emotionally induced catecholamine surge in an estrogen-deficient woman causes a combination of epicardial coronary artery constriction, constriction of the myocardial microvasculature, and direct cardiomyocyte toxicity producing a temporary stunning effect on the left ventricular myocardium.     

Incidence and significance of a positive troponin test in bacteremic patients without acute coronary syndrome

Background

Since the introduction of troponin for the diagnosis of myocardial infarction, several studies have shown additional conditions in which troponin is elevated, including sepsis. The objective of this study was to determine the incidence of an elevated troponin in patients with bacteremia and its significance.

Methods

This was a prospective, noninterventional study. Patients with a positive blood culture were included. Cardiac troponin I (cTnI) was determined within 4 days of blood culture. A repeat electrocardiogram was obtained in a sample of patients with elevated cTnI and in patients with a negative troponin test. Demographic, clinical, and microbiological data were obtained for all patients.

Results

A total of 159 bacteremic patients were included. Positive cTnI was detected in 69 patients (43%). Elevated cTnI was associated with a number of underlying diseases, hospitalization ward, severity of the systemic inflammatory condition, and kidney function (P <.05-.001). A repeat electrocardiogram was performed in 39 patients with a positive cTnI and in 28 patients with a negative cTnI. Two of 39 patients (5%) in the positive cTnI group had ischemic changes and 2 patients (5%) had nonspecific changes, whereas only 1 patient (4%) with a negative cTnI had nonspecific changes. Bivariate analysis revealed a statistically significant association for positive cTnI and mortality; however, on multivariate analysis this was no longer significant.

Conclusion

Forty-three percent of bacteremic patients had an elevated cTnI. Risk factors for elevated cTnI were severity of the underlying infection, renal function, and underlying cardiac disease. Increased cTnI was found to be a dependent risk factor and a surrogate marker for death.     

Patterns and Outcomes of Care in Children With Advanced Heart Disease Receiving Palliative Care Consultation

Context

Although access to subspecialty pediatric palliative care (PPC) is increasing, little is known about the role of PPC for children with advanced heart disease (AHD).