Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

On September 14, 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

Properties of the Binary Black Hole Merger GW150914

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 36_{-4}^{+5}M_{⊙} and 29_{-4}^{+4}M_{⊙}; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black hole is bound to be <0.7 (at 90% probability). The luminosity distance to the source is 410_{-180}^{+160}  Mpc, corresponding to a redshift 0.09_{-0.04}^{+0.03} assuming standard cosmology. The source location is constrained to an annulus section of 610  deg^{2}, primarily in the southern hemisphere. The binary merges into a black hole of mass 62_{-4}^{+4}M_{⊙} and spin 0.67_{-0.07}^{+0.05}. This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

Tests of General Relativity with GW150914

The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳30M_{⊙}, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω_{GW}(f=25  Hz)=1.1_{-0.9}^{+2.7}×10^{-9} with 90% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO and Advanced Virgo detectors operating at their projected final sensitivity.

GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of 10^{-23}/sqrt[Hz] at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914.

Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg2 to 20 deg2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

Persistent pro-inflammatory cytokines following the initiation of pegylated IFN therapy in hepatitis C infection is associated with treatment-induced depression

Pegylated interferon (IFN), the basis for chronic hepatitis C virus (HCV) treatment, causes depression in 30-40% of patients. The potential for cytokine mRNA patterns from baseline into early treatment to associate with the onset of treatment-induced depression (TID) was examined. Depression was measured by the Beck Depression Inventory at baseline and weeks 2, 4, 8 and 12 of treatment (n = 38). At baseline and weeks 2 and 4, peripheral blood mononuclear cell (PMBC, n = 28), isolated ex vivo, were examined for tumour neurosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-10 mRNA expression. In patients that developed treatment-induced depression, pro-inflammatory TNF-alpha mRNA levels from baseline into week 4 of therapy remained constant (1.1-fold increase); whereas IL-1beta transcripts decreased 3.5 fold. However, corresponding TNF-alpha (3-fold, P < 0.05) and IL-1beta (7.5-fold) transcript expression diminished to a greater extent in the absence of TID. Changes in TNF-alpha mRNA values correlated to the average change in BDI scores over the 12 weeks (r = 0.56, P < 0.05). Concomitantly, anti-inflammatory IL-10 transcript levels decreased in (TID), relative to increased expression in the absence of TID (P < 0.05). The potential influence of IL-10 was observed upon calculation of individual pro- verses anti-inflammatory mRNA ratios. Stable in the presence of depression, TNF-alpha/IL-10 and IL-1beta/IL-10 mRNA ratios declined significantly over time in its absence (P < 0.05). This study suggests that in chronic HCV infection, upon pegylated IFN administration persistent pro-inflammatory cytokine MRNA expression associates with TID. In contrast, therapeutic activation of mechanisms that decrease pro-inflammatory immunity may protect against depression during therapy.

[Epidemiology and management in emergency room patients with maxillofacial fractures]

OBJECTIVE

To minimize overall mortality and optimise reconstructive and cosmetic outcome in severely injured patients with maxillofacial injuries the interdisciplinary coordination of several surgical disciplines is required. It is still discussed controversy whether patients with maxillofacial fractures benefit from early fracture repair or if delayed operative management also yields in good results.

METHODS

Herein we analysed the data of 1252 severely injured patients between May 1998 through June 2002 in our trauma department regarding fractures of the maxillofacial region, injury severity, length of ICU stay and postoperative complications in patients with either early (within 72 hours) or delayed ( > 3 days) facial fracture repair.

RESULTS

147 patients had severe facial fractures. Average age was 39.8 years (3-87 years), mean ICU was 25 (+/- 16) and the overall mortality 12% (n = 18). The most common cause for the injuries were traffic accidents in 45%. 78 patients (53%) underwent surgical repair of the maxillofacial fractures; 18 patients had early fracture repair and 60 patients had delayed operative repair. We found 4 complications (22%) in the early repair group and 13 local complications (21%) in the group with delayed surgical repair.

CONCLUSION

Delayed repair of maxillofacial injuries in severely injured patients is feasible and yields in good results compared to early fracture repair.

Characterization of leukocytotoxic and superantigen-like factors produced by Staphylococcus aureus isolates from milk of cows with mastitis

Staphylococcus aureus is a major pathogen for cattle, causing various forms of subclinical and clinical mastitis. Two groups of virulence factors (leukotoxins and superantigens) are supposed to play an important role in the initiation and/or the exacerbation of this disease. In order to detect all known and putative members of leukotoxins and SAgs (superantigens), we tested secreted factors of different S. aureus isolates in flow cytometry-based assays. Isolates were sampled from 68 cows of different farms and cultured for 24h in vitro. Supernatants were then coincubated with purified polymorphonuclear granulocytes (PMN) or combinations of blood mononuclear cells (MNC) and PMN. Viable PMN and MNC were determined by quantitative flow cytometry. In addition, we recorded the proliferation-inducing potential of isolate supernatants for bovine MNC. Based on these criteria, the supernatants of S. aureus isolates fell in three groups. The first group (n=32), termed LT-SNs (leukotoxin-containing supernatants), killed purified granulocytes (neutrophils and eosinophils) in vitro. The second group of supernatants (n=20), termed SAg-SN (superantigen-containing supernatants), induced activation and proliferation of mononuclear cells (MNC) and, only in the presence of MNC, resulted in a selective depletion of neutrophils after 24h in vitro. The third group of supernatants (n=16) contained neither LTs or SAgs. Functionally, SAg-SNs behaved like purified staphylococcal enterotoxin A (SEA) or SEB tested in parallel. The absence of SAg-like activity in LT-SNs was confirmed by heat treatment of LT-SNs, which destroyed the leukocytotoxic activity, but did not reveal any MNC-activating potential. This study, therefore, suggests, that pathogenic S. aureus isolates either produce leukotoxins or superantigens and that both groups of virulence factors can easily be differentiated by the functional assays described. The prevalence of leukotoxin- or superantigen-producing isolates was comparable among cattle with subclinical (LT=41%; SAg=30.8%) mastitis. The higher frequency of LT-producing isolates in cases of clinical mastitis (LT=55.2%; SAg=27.6%) was not significant. At least, these findings argue against the dominant role of superantigens or leukotoxins in S. aureus-induced bovine mastitis.

Echocardiographic quantification of left ventricular asynergy in coronary artery disease with Fourier phase imaging

BACKGROUND

Visual evaluation of wall motion is subjective and may be difficult in patients with impaired left ventricular function. Current algorithms used to analyze wall motion usually neglect motion asynchrony that may be profoundly altered in coronary artery disease. This study was to investigate whether the extent of left ventricular asynergy can be used to quantify the severity of regional myocardial dysfunction by the use of Fourier phase imaging.

METHODS

Echocardiographic cine loops of 21 patients with ischemic cardiomyopathy (EF < or = 40%) were mathematically transformed using a first-harmonic Fourier algorithm displaying the sequence of wall motion as phase angles in parametric images and regional phase histograms. Segmental fractional area shortening (FAC) and qualitative assessment of regional wall motion based on visual inspection served as reference method.

RESULTS

There was an inverse linear relationship between FAC and phase angles (r = -0.75, p < 0.01). Normal endocardial motion yielded low phase angles (mean 16 +/- 15 degrees SD). With an increase in wall motion abnormalities, phase angles were progressively delayed by 56 +/- 38 degrees in hypokinetic, by 88 +/- 38 degrees in akinetic, and by 143 +/- 33 degrees (p < 0.001) in dyskinetic segments.

CONCLUSIONS

These results demonstrate that left ventricular asynchrony is an indicator of regional myocardial dysfunction in coronary artery disease. Echocardiographic Fourier phase imaging can be used to quantify wall motion displaying contraction sequence in a simple and objective format.

Prognostic value of Doppler echocardiographic mitral inflow patterns: implications for risk stratification in patients with chronic congestive heart failure

OBJECTIVES

This prospective study tested whether transmitral flow patterns add incremental value to peak oxygen consumption (VO2) in determining the prognosis of patients with chronic congestive heart failure (CHF) and systolic dysfunction.

BACKGROUND

Peak VO2 is an objective marker of functional capacity and is routinely used as a criterion to identify heart transplant candidates. Diastolic dysfunction limits functional capacity, but its prognostic importance relative to that of peak VO2 is unknown.

METHODS

Peak VO2 and mitral inflow velocities were prospectively measured in 311 consecutive patients (mean age 54 years, 84% male) with impaired left ventricular function (ejection fraction <40%; 88 patients with ischemic and 223 with dilated cardiomyopathy) who were evaluated for heart transplant candidacy.

RESULTS

During a mean follow-up period of 512 +/- 314 days, 65 patients died and 43 patients underwent heart transplantation. Diastolic filling patterns, peak VO2 and left ventricular end-diastolic diameters were independent predictors of cardiac mortality. In patients with peak VO2 < or = 14 ml/min per kg body weight, the outcome was markedly poorer in the presence of restrictive filling patterns as compared with their absence (two-year survival rate 52% vs. 80%). Similarly, despite peak VO2 levels >14 ml/min per kg, the outcome was less favorable in the presence of restrictive filling patterns (two-year survival rate 80% vs. 94%). A risk-stratification model based on the identified independent noninvasive predictors separated groups into those with high (93%), intermediate (65%) and low (39%) two-year survival rates.

CONCLUSIONS

Transmitral flow patterns add incremental value to peak VO2 in determining the prognosis of patients with CHF and impaired systolic function.

Intrauterine insemination in sows with reduced sperm number

Usually 2-3 x 10(9) sperm per insemination are used in pigs. In other species it has been shown that changing the site of insemination allows a reduction in the amount of sperm per insemination dose. The goal of this study was to determine the minimal number of sperm that can be used, without a reduction in either the pregnancy rate or the mean litter size, using surgical deep intrauterine insemination in sows after weaning. Three different sperm concentrations (5 x 10(8), 1 x 10(8) and 1 x 10(7) sperm cells extended in 0.5 mL Androhep) were inseminated into the tip of each uterine horn. In addition two groups of control sows were inseminated once intracervically 24-32 h after the first signs ofoestrus with 1 x 10(9) and 3 x 10(9) sperm in 80 mL Androhep extender. Animals that became pregnant were allowed to farrow normally. No significant differences were observed between groups inseminated surgically with the three different sperm dosages with respect to pregnancy or farrowing rate. There was also no significant difference between the results of these groups and the results obtained from the non-surgically inseminated control groups. Neither the mean number of live-born nor stillborn piglets was significantly different between the surgically inseminated groups and the control groups. The total number of piglets born in each group was also not statistically different. The data show that the sperm number to be used for surgical insemination can be lowered without loss of the fertilization potential and may be used in the field as soon as a suitable insemination device is available.

Size comparisons among integral membrane transport protein homologues in bacteria, Archaea, and Eucarya

Integral membrane proteins from over 20 ubiquitous families of channels, secondary carriers, and primary active transporters were analyzed for average size differences between homologues from the three domains of life: Bacteria, Archaea, and Eucarya. The results showed that while eucaryotic homologues are consistently larger than their bacterial counterparts, archaeal homologues are significantly smaller. These size differences proved to be due primarily to variations in the sizes of hydrophilic domains localized to the N termini, the C termini, or specific loops between transmembrane alpha-helical spanners, depending on the family. Within the Eucarya domain, plant homologues proved to be substantially smaller than their animal and fungal counterparts. By contrast, extracytoplasmic receptors of ABC-type uptake systems in Archaea proved to be larger on average than those of their bacterial homologues, while cytoplasmic enzymes from different organisms exhibited little or no significant size differences. These observations presumably reflect evolutionary pressure and molecular mechanisms that must have been operative since these groups of organisms diverged from each other.

Superantigen-dependent accelerated death of bovine neutrophilic granulocytes in vitro is mediated by blood mononuclear cells

While classical interactions of bacterial superantigens (SAgs) with antigen presenting cells and T cells have been studied intensively, the potential interactions of SAgs with granulocytes (PMNs) have gained much less attention. We investigated if in the bovine system SAgs have any direct or indirect influence on the fate of granulocytes, which are among those cells primarily responsible for the elimination of superantigen-producing bacteria. The tested SAgs (SEA, SEB) had no apparent direct effect on PMN viability (neutrophils and eosinophils). However, in the presence of blood mononuclear cells (MNCs), SAgs led to an accelerated death of neutrophils but not of eosinophils. Compared to medium controls, in SAg-stimulated cultures only about 20-50% of the neutrophils survived after 24 hours in vitro. Accelerated death of neutrophils required the presence of at least 10% MNC and started between 2.5-24 h after initiation of the co-culture between MNC and PMN. Minimal effective SEA concentrations ranged between 10-100 pg/l (SEB 0.1-10 ng/l). The effect could be mimicked by culture supernatants of SAg-stimulated MNCs, suggesting that direct cell-cell interactions are not required for the killing. In the human system, where we tested the role of TNF-alpha, an antibody specific for this cytokine was not able to abolish the death of human neutrophils. Brefeldin A, an inhibitor of golgi transport and cytokine secretion, which blocked the SAg-induced activation of bovine MNC did not abolish the killing of neutrophils. Blocking of nitric oxide generation or PGE2 synthesis also could not alter the SAg-induced killing of bovine neutrophils. The observed indirect negative effects of SAgs on neutrophils may provide new insights in mechanisms by which superantigens modulate the hosts immune response.

Low dose insemination in synchronized gilts

Conventional insemination techniques in pigs require 2 to 3 x 10(9) sperm/dose. When using the latest high-speed sperm-sorting technology, one can still sort only about 5 to 6 million sperm of each sex per hour. The objective of the present study was to find the minimal sperm concentration at a low-insemination volume in pigs without diminishing fertilization rate and litter size using surgical deep intra-uterine insemination (IUI). Semen from 3 boars was collected and diluted with Androhep to 5 x 10(8), 1 x 10(8), 1 x 10(7), 5 x 10(6) or 1 x 10(6) sperm/0.5 ml. In trial 1, 109 prepuberal gilts were synchronized and surgically inseminated into the tip of each uterine horn 32 h or 38 h after hCG treatment or at the time of ovulation, respectively. Pregnant gilts were allowed to go to term. Pregnancy and farrowing rates did not differ significantly except at the lowest sperm concentration if inseminated 32 h or 38 h after hCG treatment (p < 0.05). No differences were found among insemination groups for the total number of piglets, number of piglets born alive, stillborn piglets, and mummified fetuses. In trial 2, 34 gilts were inseminated as described above 32 h after hCG. Additionally, 9 gilts were inseminated once nonsurgically with 1 x 10(9) sperm as controls. Gilts were slaughtered 48 h after insemination, and embryos were recovered. Embryos were cultured in NCSU 23 (120 h), evaluated morphologically and stained with fluorescent dye (Hoechst 33342) to visualize nuclei. Recovery rates varied between 71.4% and 84.4%. Fertilization rate of the lowest sperm concentration (1 x 10(6) sperm/horn) differed significantly (p < 0.05) from all other groups. Cleavage rates at specific developmental stages did not differ. After 5 days of in vitro culture, embryos developed to morulae and blastocysts. No differences were found for these stages. In conclusion, no major differences were found between insemination groups as long as the sperm dosage was at least 10 million sperm per gilt. The low volume was sufficient for successful deep intra-uterine insemination. Embryo development was comparable to the controls.

Production of 15-HETE by cultured smooth muscle cells from cerebral artery

Hydroperoxyeicosatetraenoic acids (HPETEs) are potent vasoconstrictors which have been implicated in the pathogenesis of the delayed cerebrovascular spasm which follows subarachnoid haemorrhage. We have previously shown that one of their stable breakdown products, 15-hydroxyeicosatetraenoic acid (15-HETE), is the major lipoxygenase product released from isolated cerebral arteries. To investigate the vascular cell type responsible for their production we have established the culture of smooth muscle cells from cerebral arteries and have measured their release of HETEs upon stimulation with arachidonic acid. The cultured cells isolated from bovine cerebral arteries expressed smooth muscle phenotype as they stained positively for smooth muscle alpha-actin and not factor VIII-related antigen. Furthermore, these cells possessed the calcium and potassium conductances characteristic of smooth muscle cells. Upon incubation with arachidonic acid, the major lipoxygenase product was 15-HETE; no leukotrienes were detected. The formation of 15-HETE was concentration-dependent and was attenuated by nordihydroguaiaretic acid, but not by indomethacin. Similar to intact cerebral artery, cultured cerebrovascular smooth muscle cells have lipoxygenase activity, the major product of which is 15-HETE. These results are consistent with a possible role of the HPETEs in the pathogenesis of cerebral vasospasm.

Glibenclamide relaxes vascular smooth muscle constriction produced by prostaglandin F2 alpha

The present study has demonstrated: (1) glibenclamide can reduce resting tension in canine cerebral arteries but has no effect on resting tension in the rat aorta; (2) glibenclamide can relax prostaglandin F2 alpha-induced contractions in the rat aorta, and in canine femoral, mesenteric, renal, coronary, basilar and middle cerebral arteries; (3) the relaxation produced by glibenclamide in rat aorta is comparable to that of glyceryl trinitrate and stronger than that of papaverine; (4) canine femoral arteries are less sensitive to glibenclamide than the other arteries; (5) in cerebral arteries glibenclamide was as effective as papaverine, but less effective than glyceryl trinitrate; (6) the actions of glibenclamide on cerebral arteries are not mediated by cGMP as they were not blocked by methylene blue, an inhibitor of guanylate cyclase; (7) the effects of glibenclamide are not endothelium-dependent. The mechanism by which glibenclamide produces relaxation is not clear; while the drug is known to block ATP-dependent potassium channels, in vascular smooth muscle this would cause contraction, not dilation. The action of glibenclamide may be at the level of the receptor or the signal transduction process.

Mechanisms of arachidonic acid-induced contractions of canine cerebral arteries

The effects of arachidonic acid in cerebral blood vessels has been examined using rings of canine cerebral arteries. Arachidonic acid produced dose-dependent contractions of this preparation even after mechanical removal of the endothelium. The contractions were not blocked by indomethacin or acetylsalicylic acid, both of which inhibit cyclooxygenase, but were inhibited by nordihydroguaiaretic acid which is a lipoxygenase inhibitor, BW 755c which blocks both pathways, and FPL 55712 which is an antagonist at leukotriene receptors. These data imply that arachidonic acid-induced contractions are mediated by products of the lipoxygenase pathway. Leukotrienes and cyclooxygenase products are generated by this preparation as shown by HPLC and radioimmunoassay and both LTC4 and LTD4 produce contractions in cerebral arteries lending further evidence in support of this suggestion.

Nimodipine and chronic vasospasm in monkeys: Part 1. Clinical and radiological findings

The efficacy of the calcium channel blocker nimodipine in the prevention of chronic cerebral vasospasm (VSP) and delayed ischemia after subarachnoid hemorrhage (SAH) in monkeys was examined in a blind, randomized, placebo-controlled trial. The primate model developed in this laboratory reliably induces chronic cerebral vasospasm and can induce pathologically proven delayed ischemic neurological deficits (DINDs). With standard microsurgical procedures, an average 6.4-ml autologous hematoma was placed directly against the major anterior cerebral vessels in the right basal subarachnoid spaces of 24 monkeys. The monkeys were randomized to one of four groups and were treated orally q8h for 7 days with nimodipine (3, 6, or 12mg/kg)or placebo. An additional 2 monkeys underwent the surgical procedure without clot placement. Drug administration began between 14 and 20 hours after clot placement. Indices monitored before and after SAH included neurological status, angiographic cerebral vessel caliber, and cerebral blood flow. Significant VSP (25 to 100% reduction in vessel caliber) was present on Day 7 on the clot side in 83% of the animals (P less than or equal to 0.001). There was no significant difference (P greater than 0.05) in the incidence of VSP among the four groups. Similarly, there was no significant difference (P greater than 0.05) in the mean vessel caliber reduction after SAH among the four treatment groups. There was no VSP present on Day 7 in the sham-operated animals. One animal receiving high dose nimodipine (12 mg/kg p.o. q8h) developed a DIND on Day 5 after SAH. A second animal in the 12-mg/kg group developed a transient neurological deficit between Days 4 and 7.

Nimodipine and chronic vasospasm in monkeys: Part 2. Pharmacological studies of vessels in spasm

The effect of nimodipine on the in vitro reactivity of cerebral vessels after subarachnoid hemorrhage (SAH) was studied. With the use of a primate model of chronic cerebral vasospasm, 12 female cynomolgous monkeys underwent the induction of a SAH by the direct placement of an average 6.4-ml autologous hematoma against the major anterior cerebral vessels in the right basal subarachnoid spaces (Day 0). The animals were then randomized to one of four groups and within 14 to 20 hours after clot placement were started on oral q8h therapy with nimodipine (3, 6, or 12 mg/kg) or placebo. On Day 7, the animals were killed and the right and left middle cerebral arteries (MCAs) were immediately resected and placed in oxygenated Krebs' solution. Ring preparations from the arteries were suspended in organ baths, and dose-effect curves to varying concentrations of norepinephrine, 5-hydroxytryptamine, and potassium chloride were obtained. There was a highly significant reduction in the response of the MCA on the clot side (right) relative to the nonclot side (left) to all three agonists. The clot side contractility was not influenced by nimodipine treatment at any of the four doses tested. The nonclot side arteries of the 12-mg/kg treatment group demonstrated significantly enhanced reactivity for all three agonists. Oral treatment with high dose nimodipine enhances the reactivity of normal cerebral vessels to the agonists tested, but it does not seem to affect the reactivity of arteries in chronic spasm at any of the four doses tested.

Irreversible blockade of responses to a partial agonist acting at the histamine H1-receptor

N,N-Diethyl-2-(1-pyridyl)-ethylamine (E-2-P) has been shown previously to behave as a simple partial agonist at the histamine H1-receptor of guinea-pig ileum. When isolated longitudinal muscle strips from this preparation were tested with E-2-P before and after blockade with 2-haloalkylamines, it was found that these agents produced an irreversible shift to the right in the dose-response curve without significant depression of the maximum response even at very high antagonist concentrations. Under these circumstances the maximum response to the partial agonist may exceed the maximum response to histamine itself since the latter shows a much diminished maximum response at a very high concentrations of antagonist. These findings are not readily explicable in terms the usual "receptor-reserve' model of the histamine receptor system in ileum. A tentative explanation is provided, involving interaction with the antagonist at more than one site.