Medical response times to major incidents: potential benefits of a regional air ambulance mutual aid scheme.

In the event of major incidents, neighbouring air ambulances can be used to assist. To assess the potential benefit of this cooperation, three fictitious major incidents were described to emergency service dispatch desks to assess the availability and response times for neighbouring air ambulances. A medical infrastructure at each site could be in place in a shorter time when the mutual aid scheme was used. This short study demonstrates the increased availability of doctors and flight paramedics that can be achieved by cooperation schemes. The costs of such schemes are minimal where air ambulances already exist. Ambulance services can use this type of scheme rapidly to place a comprehensive medical infrastructure for major incidents.

Diazoxide-induced cardioprotection requires signaling through a redox-sensitive mechanism.

Diazoxide, a selective opener of the mitochondrial ATP-sensitive potassium channel, has been shown to elicit tolerance to ischemia in cardiac myocytes and in perfused heart. However, the mechanism of this cardioprotection is poorly understood. Because reactive oxygen species (ROS) are recognized as important intracellular signaling molecules and have been implicated in ischemic preconditioning, we examined diazoxide-induced ROS production in adult cardiomyocytes. Cells treated with 50 micromol/L diazoxide showed a 173% increase in ROS production relative to baseline. 5-Hydroxydecanoate was found to attenuate the diazoxide-induced increase in ROS generation. The diazoxide-induced increase in ROS also was abrogated by the addition of either the antioxidant N-acetylcysteine (NAC) or N-mercaptopropionylglycine. We also examined the ability of NAC to block the protective effects of diazoxide in the perfused rat heart. After 20 minutes of global ischemia and 20 minutes of reflow, hearts perfused with 100 micromol/L diazoxide before ischemia showed significantly improved postischemic contractile function relative to untreated hearts (84% versus 29% of initial left ventricular developed pressure, respectively). Hearts treated with diazoxide in the presence of 4 mmol/L NAC recovered 53% of initial left ventricular developed pressure, whereas hearts treated with NAC alone recovered 46% of preischemic function. Using (31)P NMR spectroscopy, we found that, similar to preconditioning, diazoxide significantly attenuated ischemia-induced intracellular acidification and enhanced post- ischemic recovery of phosphocreatine levels, both of which were blocked by cotreatment with NAC. These data suggest that the cardioprotective actions of diazoxide are mediated by generation of a pro-oxidant environment.

Characterization of the solid state: quantitative issues.

Quantitative analysis of solid state composition is often used to ensure the safety and efficacy of drug substances or to establish and validate the control of the pharmaceutical production process. There are a number of common techniques that can be applied to quantify the phase composition and numerous different methods for each technique. Each quantitative option presents its own issues in ensuring accuracy and precision of the solid state method. The following article describes many of the common techniques that are used for quantitative phase analysis and many of the considerations that are necessary for the development of such methods.

Dexamethasone for the treatment of depression: a preliminary report.

BACKGROUND: This preliminary uncontrolled trial of intravenous dexamethasone addresses the question of the utility of a glucocorticoid for the treatment of depression. METHOD: Patients with a DSM-III-R (SCID confirmed) diagnosis of major depression or bipolar disorder, depressed type, and a Hamilton Rating Scale for Depression (HAM-D) score of greater than or equal to 20 were selected. Baseline HAM-D scores were compared with scores within 10 days after intravenous infusion of dexamethasone; data were analyzed by t tests. Control subjects (no psychiatric illness and HAM-D scores less than 5) were given intravenous dexamethasone to test for its mood-altering effect. RESULTS: The mean HAM-D scores in 16 depressed subjects 10 days after intravenous dexamethasone dropped by 56% (p less than .0001), and 75% of the patients experienced a greater than 50% reduction in HAM-D scores. Additionally, 6 nonpsychiatric, nondepressed control subjects were given intravenous dexamethasone and found to have no changes in mental status examination. CONCLUSIONS: Intravenous dexamethasone may be an effective treatment for depressive illnesses. Because this was an uncontrolled, unblinded trial, further studies need to be done in nonpsychiatric and psychiatric controls to ascertain the validity of this finding.

Modification of kainate-induced behavioral and electrographic seizures following inhibition of nitric oxide synthase in mice.

We assessed the effects of N(omega)-nitro-L-arginine-methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), on behavioral and electrographic seizures elicited in mice by convulsant doses of kainate. In Expt. 1, L-NAME dose-dependently potentiated the convulsant effects of kainate (44 mg/kg s.c.), transforming long-latency clonic convulsions into short-latency fits of wild-running, and increased the incidence of kainate-induced mortality. The proconvulsant effects of L-NAME (5 mg/kg i.p.) did not reflect shortened latency to kainate-induced epileptiform afterdischarge recorded via electrodes chronically implanted into the hippocampus, amygdala, frontal cortex or mesencephalic reticular formation (Expt. 2). We also observed a dramatic uncoupling of behavioral and electrographic seizures in mice treated with L-NAME 30 min prior to kainate: 4/6 mice treated with L-NAME failed to express afterdischarge from any of the sites assessed during fits of wild-running. The proconvulsant effects of L-NAME were dependent on the route of administration of kainate, as the inhibitor of NOS failed to alter behavioral (clonic) or electrographic seizures elicited by intrahippocampal kainate (1 nmol, Expt. 3) yet shortened latency to fits of wild-running following i.c.v. kainate (1 nmol, Expt. 4) and reduced the dose of systemic kainate required for either clonic convulsions or wild-running (Expt. 5). The observations that L-NAME potentiates kainate-induced wild-running but not necessarily clonus suggest the involvement of tectopontine mechanisms.

A method for measuring potency of narasin extracts using near-IR spectroscopy.

We present a method for extracting the active component from granulated narasin samples using chloroform with subsequent quantitation by near-infrared absorption spectroscopy (NIRS). A multiple linear regression (MLR) calibration equation was developed using a set of 41 calibration samples. The potencies obtained using NIR analysis exhibit no larger than an 8% (3.03 mg/g) error when compared to results based on the primary HPLC reference method. We estimate the detection limit using this method to be 400 ppm narasin (20 mg/g potency), and the standard deviation for five independent extractions of the same sample is approximately 24 ppm (approximately 1.2 mg/g potency or approximately 1%). We also present the results from a robustness study based upon a full factorial experimental design in which we varied extraction and measurement parameters. This study indicates that sample mass causes the most variation in the results. Bottle-to-bottle variations in the chloroform used for the extraction also proved significant. Variations in sample batch, number of spectral scans, and the interactions between sample hatch*soneration time, no. Scans*time in NIR, and sample batch*sample mass were borderline significant.

Development and validation of analytical methodology for near-infrared conformance testing of pharmaceutical intermediates.

An approach was developed to create and validate analytical methods to perform near-infrared (NIR) conformance testing on two isolated intermediates used in the manufacture of loracarbef monohydrate bulk drug substance. Method calibration sets were developed from second-derivative NIR reflectance spectra for 30 representative batches of each intermediate. In conformance testing, second-derivative NIR spectra for samples from newly manufactured batches are compared with the calibration set. If the new spectrum is not statistically different to the average of the calibration set, the sample passes the conformance test. Using authentic batch samples of typical and low-potency lots, the methods were validated for accuracy, selectivity, ruggedness and repeatability of the methods.

Measurement of potency and lipids in monensin fermentation broth by near-infrared spectroscopy.

A transmission near-infrared (NIR) spectroscopic method for quantification of potency and lipids in monensin fermentation broth was developed and validated. Two multiple linear regression calibration curves were established for a set of 100 fermentation samples, correlating the appropriate absorption bands in the NIR spectrum to the laboratory reference methods; high-performance liquid chromatography for potency, and chloroform extraction for lipids. During method development, potency was found to be well correlated to NIR absorbances specific for monensin. While acceptable, correlation of NIR absorbances characteristic of oil to the chloroform lipid method was weaker due to a greater amount of relative variation in the lipid measurements. Following establishment of the optimal calibration curves, the NIR method for potency and lipids was validated for selectivity, accuracy, precision, and robustness. In order to investigate long-term drift in the measurement system, samples were tested both by the NIR and the reference methods over a 7-month period. The differences between results from the two measurements were calculated and statistically analyzed.

Herpes simplex virus-1 replication in histiotypic rotation-mediated reaggregated murine brain.

Inbred mouse strains exhibit varying susceptibilities to severe herpes simplex virus (HSV)-1-related neurologic disease. HSV-1 replication was examined in neural tissue obtained from mouse strains susceptible (A/J, SJL), moderately resistant (Balb/c), or resistant (C57BL/6) to severe HSV-1 disease. Reaggregated brain cultures were prepared from mechanically dissociated fetal mouse brains maintained with constant rotation. The resulting aggregates each contain neurons, astrocytes, oligodendrocytes, and microglia. These were inoculated with 10(-2)-10(4) plaque-forming units (pfu) HSV-1 MacIntyre/aggregate. Aggregates and media were harvested at 24, 48, 72, and 96 hr post-inoculation (p.i.) and assayed for virus production by plaque titration. Brain cultures prepared from A/J, SJL, Balb/c, and C57BL/6 mice supported HSV-1 replication equally well: by 96 hr p.i., titers of 10(6) pfu/ml were produced by each strain at each inoculum. ID50s were similar for A/J and C57BL/6 cultures. There was no increased capacity for HSV-1 replication or for permissiveness for HSV-1 infection in histiotypic brain cultures from mouse strains susceptible to severe HSV-1 disease.

Elevated calcium in preneoplastic cells activates NF-kappa B and confers resistance to apoptosis.

Early preneoplastic cells (sup+) exhibit increased susceptibility to apoptosis, which is lost in late stage preneoplastic cells (sup-). Sup+ cells, which undergo apoptosis when cultured in low serum, show little or no DNA binding activity to nuclear factor (NF)-kappa B either in 10% or 0.2% serum. In contrast sup- cells, which are resistant to apoptosis in low serum, show a sustained constitutive activation of NF-kappa B. The constitutive activation of NF-kappa B observed in sup- cells is not due to loss of I kappa B alpha. We considered that the activation of NF-kappa B in sup- cells might be secondary to an increase in cytosolic Ca(2+), since sup- cells have a cytosolic Ca(2+) level that is double that in sup+ cells. In support of a role for Ca(2+), lowering cytosolic Ca(2+) in sup- cells by addition of the cell-permeable Ca(2+) chelator 1,2 bis(O-aminophenoxy)ethane-N, N, N', N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) reduced cytosolic Ca(2+) by approximately 31% relative to untreated sup- cells, concomitant with a 65% reduction in NF-kappa B DNA binding activity and a reduction in I kappa B kinase (IKK) activity. In sup- cells in low serum, addition of BAPTA-AM also resulted in a significant ( approximately 50%) increase in caspase-3 activity. Raising extracellular Ca(2+) in sup+ cells resulted in a slight activation of I kappa B kinase and in enhanced NF-kappa B DNA binding activity. Using proteasome and calpain inhibitors, we determined that the basal activity of NF-kappa B in sup- cells is largely proteasome-independent, but sensitive to calpain inhibitors. Taken together these data suggest that the elevated Ca(2+) in sup- cells causes a modest activation of IKK, which likely contributes to the enhanced basal activation of NF-kappa B in sup- cells; however, the predominant effect of Ca(2+) appears to be mediated by Ca(2+)-enhanced degradation by calpain.