Clinical utility of 64-row multislice CT angiography in the detection of cerebral aneurysms in acute subarachnoid haemorrhage

CT angiography (CTA) is a fast examination performed with a time-optimised contrast injection to enhance the cerebral arteries. Being a new imaging modality in our hospital, evaluation of the effectiveness of 64-row multislice CTA in detecting intracranial aneurysms in ruptured subarachnoid haemorrhage (SAH) cases is necessary. We conducted a descriptive prospective study by recruiting 30 consecutively operated SAH cases from May 2005 until November 2006. CTA findings were studied by radiologist and neurosurgeon and these were compared with operative findings. The sensitivity and specificity of CTA were 94.4% and 97.2% respectively. Approximately half of the patients were scanned within four hours and operated within 24 hours. In conclusion, CTA proves to be highly sensitive and specific in the diagnosis of intracranial aneurysms in our study.

Dose-dependent response of FGF-2 for lymphangiogenesis

Spatio-temporal studies on the growth of capillary blood vessels and capillary lymphatic vessels in tissue remodeling have suggested that lymphangiogenesis is angiogenesis-dependent. We revisited this concept by using fibroblast growth factor 2 (FGF-2) (80 ng) to stimulate the growth of both vessel types in the mouse cornea. When we lowered the dose of FGF-2 in the cornea 6.4-fold (12.5 ng), the primary response was lymphangiogenic. Further investigation revealed that vascular endothelial growth factor-C and -D are required for this apparent lymphangiogenic property of FGF-2, and when the small amount of accompanying angiogenesis was completely suppressed, lymphangiogenesis remained unaffected. Our findings demonstrate that there is a dose-dependent response of FGF-2 for lymphangiogenesis, and lymphangiogenesis can occur in the absence of a preexisting or developing vascular bed, i.e., in the absence of angiogenesis, in the mouse cornea.

Mitochondrial involvement in the point of no return in neuronal apoptosis

Programmed cell death (PCD) contributes to development, maintenance, and pathology in various tissues, including the nervous system. Many molecular, biochemical, and genetic events occur within cells undergoing PCD. Some of these events are incompatible with long-term cell survival because they have irreversible, catastrophic consequences. The onset of such changes marks the point of no return, a decisive regulatory event termed 'the commitment-to-die.' In this review, we discuss events that underlie the commitment-to-die in nerve growth factor-deprivation-induced death of sympathetic neurons. Findings in this model system implicate the mitochondrion as an important site of regulation for the commitment-to-die in the presence or absence of caspase inhibition.

The impact of herbal medicines on dermatologic surgery

BACKGROUND

In recent years herbal medicines and supplements have become increasingly popular. With their increased popularity, more publications are warning about the potential harmful effects of some of these products.

OBJECTIVE

To present scientific evidence of the benefits and surgical risks of herbal products.

METHODS

A Medline search and review of the literature was performed.

RESULTS

Many herbal medicines are relevant in dermatologic surgery since Ginkgo biloba, garlic, ginger, ginseng, feverfew, and vitamin E may increase the risk of bleeding, and ephedra may potentiate the side effects of epinephrine.

CONCLUSION

Dermatologists should be aware of these herbal products and their uses. Many of these products prescribed by alternative medicine physicians or purchased over the counter should be discontinued prior to dermatologic surgery to minimize the risk of surgical complications.

A randomized trial of the efficacy of a new micronized formulation versus a standard formulation of isotretinoin in patients with severe recalcitrant nodular acne

BACKGROUND

Isotretinoin is very frequently the drug of choice for the management of severe recalcitrant nodular acne. Recently, a new micronized and more bioavailable formulation of isotretinoin has been developed that permits once-daily administration in lower doses than usually used with standard isotretinoin (Accutane), regardless of whether it is taken with or without food.

OBJECTIVE

Our purpose was to determine whether micronized isotretinoin and standard isotretinoin are clinically equivalent.

METHODS

In this multicenter, double-blind, double-dummy study, 600 patients with severe recalcitrant nodular acne were treated with either 0.4 mg/kg of micronized isotretinoin once daily without food (n = 300) or 1.0 mg/kg per day of standard isotretinoin in two divided doses with food (n = 300). Lesion counts were monitored over 20 weeks.

RESULTS

Both treatment groups in this well-controlled clinical trial experienced an equivalent reduction in the number of total nodules (facial plus truncal). In addition, an equivalent proportion of patients achieved 90% clearance of the total number of nodules. Both formulations had similar results for other efficacy variables.

CONCLUSION

Once-daily use of the micronized and more bioavailable formulation of isotretinoin under fasted conditions is clinically equivalent to the standard twice-daily formulation under fed conditions in the treatment of severe recalcitrant nodular acne.

Safety of a new micronized formulation of isotretinoin in patients with severe recalcitrant nodular acne: A randomized trial comparing micronized isotretinoin with standard isotretinoin

BACKGROUND

Isotretinoin is a very effective drug for treating severe recalcitrant nodular acne. A new micronized formulation of isotretinoin has been shown to be clinically equivalent to standard isotretinoin with improved bioavailability and minimal food effect. The safety profile of the micronized formulation has not been described previously.

OBJECTIVE

The objective of this article is to report the incidence and intensity of adverse events found in a comparative, double-blind efficacy study that showed clinical equivalence of the new micronized formulation of isotretinoin and the standard isotretinoin formulation (Accutane).

METHODS

Six hundred patients with severe recalcitrant nodular acne were treated with micronized isotretinoin (n = 300) under fasted conditions or standard isotretinoin (n = 300) under fed conditions. One cohort received single daily doses of 0.4 mg/kg of micronized isotretinoin without food and the other cohort received 1.0 mg/kg per day of standard isotretinoin in two divided doses with food. Adverse events were monitored during 20 weeks of drug therapy.

RESULTS

The proportion of adverse events in most body systems was generally lower in patients receiving micronized isotretinoin than in those receiving standard isotretinoin.

CONCLUSION

Micronized isotretinoin appears to have a safety profile similar to that of standard isotretinoin and to carry a lower risk of mucocutaneous events and hypertriglyceridemia.

Lipopolysaccharide-induced gastroprotection is independent of the vagus nerve

This study was done to examine the role of the vagus nerve in a model of gastric injury during endotoxemia. In conscious rats, lipopolysaccharide (LPS; 20 mg/kg i.p.) treatment for 5 hr prevented macroscopic gastric injury caused by acidified ethanol (150 mM HCl/50% ethanol). In addition, LPS enhanced gastric luminal fluid accumulation, decreased gastric mucosal blood flow (laser Doppler), and increased plasma gastrin levels (radioimmunoassay). Subdiaphragmatic truncal vagotomy, performed 7 days prior to LPS inhibited LPS-induced fluid accumulation, further reduced gastric mucosal blood flow following LPS, and augmented LPS-induced gastrin release compared to those in pyloroplasty controls. Atropine (1 mg/kg i.p.) prevented LPS-induced fluid accumulation but did not influence the effects of LPS on blood flow or gastrin release. Neither vagotomy nor atropine negated LPS-induced gastroprotection. This is the first report to examine the role of cholinergic nerves in the stomach during endotoxemia. The data indicate that LPS causes accumulation of gastric luminal fluid in part through its effects on cholinergic nerves. In contrast, the effects of vagotomy on blood flow and gastrin release following LPS involve a noncholinergic pathway. However, LPS-induced gastroprotection is independent of the vagus nerve.

Activation of the BRLF1 promoter and lytic cycle of Epstein-Barr virus by histone acetylation

Histone acetylation alters the chromatin structure and activates the genes that are repressed by histone deacetylation. This investigation demonstrates that treating P3HR1 cells with trichostatin A (TSA) activates the Epstein-Barr virus (EBV) lytic cycle, allowing the virus to synthesize three viral lytic proteins-Rta, Zta and EA-D. Experimental results indicate that TSA and 12-O:-tetradecanoylphorbol-13-acetate synergistically activate the transcription of BRLF1, an immediate-early gene of EBV. Chromatin immunoprecipitation assay reveals that histone H4 at the BRLF1 promoter is acetylated after P3HR1 cells are treated with TSA, suggesting that histone acetylation activates BRLF1 transcription. Furthermore, results in this study demonstrate that mutation of a YY1-binding site in the BRLF1 promoter activates BRLF1 transcription 1.6- and 2.3-fold in P3HR1 cells and C33A cells, respectively. Real time PCR analysis reveals that the mutation also increases the histone acetylation level of the nucleosomes at the BRLF1 promoter 1. 64- and 3.08-fold in P3HR1 and C33A cells, respectively. Results presented herein suggest that histone deacetylation plays an important role in maintaining the viral latency and histone acetylation at the BRLF1 promoter allows the virus to express Rta and to activate the viral lytic cycle.

[A study on thermal decomposition mechanism and quality analysis of pearl powder]

OBJECTIVE

To establish a rapid and convenient method for distinguishing genuine from sham of pearl powder as well as appraising its quality preliminarily.

METHOD

Thermogravimetry and differential thermogravimetry.

RESULT

The TG and DTG curves can be divided into two characteristic regions. The first step ranges from 250 to 380 degrees C with a weight loss of about 3%, resulting from the denaturalization and decomposition of organic matter in the powder; and the second step from 600 to 780 degrees C with a weight loss of about 40% resulting from the decomposition of calcium carbonate in the powder.

CONCLUSION

According to the two characteristic regions on TG and DTG curves along with corresponding parameters, pearl powder can be appropriately authenticated. Being related directly to the contents of organic matter in pearl powder, the first step is an important criterion for quality appraisal.

Nitric oxide synthase inhibition negates bombesin-induced gastroprotection

BACKGROUND

Bombesin prevents gastric injury primarily by the release of endogenous gastrin. Gastroprotection by exogenous gastrin is negated by nitric oxide synthase inhibition, which implicates a role for nitric oxide as a protective mediator. Because both endothelial and inducible isoforms of this enzyme can play a role in mucosal defense, this study was done to examine the contrasting effects of 2 nitric oxide synthase inhibitors on bombesin-induced gastroprotection.

METHODS

Rats were given subcutaneous saline or bombesin (10-100 microg/kg) 30 minutes before they received a 1-mL orogastric bolus of acidified ethanol (150 mmol/L of hydrochloric acid/50% ethanol) and rats were killed 5 minutes later for assessment of macroscopic injury (mm(2)). Gastric mucosal blood flow was measured by laser Doppler. Endothelial, neural, and inducible nitric oxide synthase were assessed by using Western immunoblot.

RESULTS

Bombesin decreased gastric mucosal damage, and dose-dependently increased blood flow when compared with saline-treated rats. Endothelial but not neural or inducible nitric oxide synthase immunoreactivity was increased by bombesin. In additional studies, intraperitoneal administration of N(G)-nitro-l-arginine methyl ester (l-NAME, 5-10 mg/kg), a nonselective nitric oxide synthase inhibitor, negated bombesin-induced gastroprotection and hyperemia, whereas the selective inducible inhibitor aminoguanidine (45 mg/kg) did not. Subcutaneous (SC) l-arginine (300 mg/kg), but not d-arginine, abolished the effects of l-NAME.

CONCLUSIONS

Taken together, these data suggest that nitric oxide produced by the endothelial isoform of nitric oxide synthase plays an important role in mediating the gastroprotective and hyperemic actions associated with bombesin.

Injectability and tissue compatibility of poly-(N-vinyl-2-pyrrolidone) in the skin of rats: a pilot study

BACKGROUND

Filling substances have been used in dermatologic surgery for decades, but an ideal agent has yet to be discovered. Poly-(N-vinyl-2-pyrrolidone) is a hydrogel that has been used in medical settings for more than 50 years, but not as a cutaneous filling agent.

OBJECTIVE

We investigated the intracutaneous injectability and tissue compatibility of this hydrogel in a rat model. Particular attention was paid to ease of injection through small needles, volume retention of the implant, clinical course, and histocompatibility.

METHODS

The shaved backs of 12 anesthetized Sprague-Dawley rats were injected with the sterilized hydrogel and the rats closely observed. The rats were sacrificed in groups of four at 2, 4, and 12 weeks after implantation. Implant size was measured, volume calculated, and biopsies taken at each time interval.

RESULTS

Poly-(N-vinyl-2-pyrrolidone) is easily injected through 30-gauge needles. All rats tolerated the implants well clinically. Histopathology revealed well-circumscribed implants with pseudoencapsulation, neoangiogenesis, and mixed inflammatory cells predominating at the periphery. Volume calculations revealed an average of 33% reduction at 4 weeks and 35% reduction at 12 weeks.

CONCLUSION

Poly-(N-vinyl-2-pyrrolidone) is easy to inject intracutaneously and is well tolerated in the rat model. Short-term volume retention is good. Histopathology suggests a subclinical inflammatory reaction expected with implantation of a synthetic substance into the skin. Additional studies are necessary to investigate the continued persistence of the hydrogel and its long-term effects on surrounding tissue.

Unique lipoproteins secreted by primary astrocytes from wild type, apoE (-/-), and human apoE transgenic mice

Composition of central nervous system lipoproteins affects the metabolism of lipoprotein constituents within the brain. The epsilon4 allele of apolipoprotein E (apoE) is a risk factor for Alzheimer's disease via an unknown mechanism(s). As glia are the primary central nervous system cell type that synthesize apoE, we characterized lipoproteins secreted by astrocytes from wild type (WT), apoE (-/-), and apoE transgenic mice expressing human apoE3 or apoE4 in a mouse apoE (-/-) background. Nondenaturing size exclusion chromatography demonstrates that WT, apoE3, and apoE4 astrocytes secrete particles the size of plasma high density lipoprotein (HDL) composed of phospholipid, free cholesterol, and protein, primarily apoE and apoJ. However, the lipid:apoE ratio of particles containing human apoE is significantly lower than WT. ApoE localizes across HDL-like particle sizes. ApoJ localizes to the smallest HDL-like particles. ApoE (-/-) astrocytes secrete little phospholipid or free cholesterol despite comparable apoJ expression, suggesting that apoE is required for normal secretion of astrocyte lipoproteins. Further, particles were not detected in apoE (-/-) samples by electron microscopy. Nondenaturing immunoprecipitation experiments indicate that apoE and apoJ reside predominantly on distinct particles. These studies suggest that apoE expression influences the unique structure of astrocyte lipoproteins, a process further modified by apoE species.

Functional and transcriptional analyses of a fengycin synthetase gene, fenC, from Bacillus subtilis

A 37-kb DNA fragment containing five fengycin synthetase genes, including fenC, fenD, fenE, fenA, and fenB, was cloned and sequenced. Among these genes, fenC encodes a fengycin synthetase 2,560 amino acids long with an estimated molecular mass of 287 kDa. This protein contains two amino acid activation modules, FenC1 and FenC2, which activate L-glutamic acid and L-ornithine, respectively. Primer extension, using mRNA isolated from the log-phase cells, identified a transcription start site located 86 nucleotides upstream from the initiation codon of fenC, implying that a promoter is located upstream from the start site. Primer extension using total RNA isolated from stationary-phase cells also identified a transcription start site located 61 nucleotides upstream from the initiation codon of fenC. Gene fusion studies demonstrated that in nHA medium, the cells transcribe the fengycin synthetase genes at two different stages of cell growth. The promoter is active during the log phase, and the activity reaches the highest level during the late log phase. The activity decreases sharply but is maintained at a low level for approximately 24 h after cells enter the early stationary phase. The results of this investigation also suggest that the transcription of fenC is positively regulated during the late log phase. Results presented herein provide further insight into fengycin synthesis by B. subtilis F29-3.

RS-127445: a selective, high affinity, orally bioavailable 5-HT2B receptor antagonist

Efforts to define precisely the role of 5-HT2B receptors in normal and disease processes have been hindered by the absence of selective antagonists. To address this deficiency, we developed a series of naphthylpyrimidines as potentially useful 5-HT2B receptor antagonists. RS-127445 (2-amino-4-(4-fluoronaphth-1-yl)-6-isopropylpyrimidine) was found to have nanomolar affinity for the 5-HT2B receptor (pKi = 9.5+/-0.1) and 1,000 fold selectivity for this receptor as compared to numerous other receptor and ion channel binding sites. In cells expressing human recombinant 5-HT2B receptors, RS-127445 potently antagonized 5-HT-evoked formation of inositol phosphates (pK(B) = 9.5+/-0.1) and 5-HT-evoked increases in intracellular calcium (pIC50 = 10.4+/-0.1). RS-127445 also blocked 5-HT-evoked contraction of rat isolated stomach fundus (pA2 = 9.5+/-1.1) and (+/-)alpha-methyl-5-HT-mediated relaxation of the rat jugular vein (pA2 = 9.9+/-0.3). RS-127445 had no detectable intrinsic activity in these assays. In rats, the fraction of RS-127445 that was bioavailable via the oral or intraperitoneal routes was 14 and 60% respectively. Intraperitoneal administration of RS-127445 (5 mg kg(-1)) produced plasma concentrations predicted to fully saturate accessible 5-HT2B receptors for at least 4 h. In conclusion, RS-127445 is a selective, high affinity 5-HT2B receptor antagonist suitable for use is vivo. The therapeutic potential of this molecule is being further evaluated.

Expression of human apolipoprotein E reduces amyloid-beta deposition in a mouse model of Alzheimer's disease

The epsilon4 allele of apolipoprotein E (apo E) is associated with an increased risk for developing Alzheimer's disease (AD). This may be due to interactions between apo E and the amyloid-beta protein (Abeta). To assess the effects of human apo E isoforms on Abeta deposition in vivo, we bred apo E3 and apo E4 hemizygous (+/-) transgenic mice expressing apo E by astrocytes to mice homozygous (+/+) for a mutant amyloid precursor protein (APPV717F) transgene that develop age-dependent AD neuropathology. All mice were on a mouse apo E null (-/-) background. By nine months of age, APPV717F+/-, apo E-/- mice had developed Abeta deposition, and, as reported previously, the quantity of Abeta deposits was significantly less than that seen in APPV717F+/- mice expressing mouse apo E. In contrast to effects of mouse apo E, similar levels of human apo E3 and apo E4 markedly suppressed early Abeta deposition at nine months of age in APPV717F+/- transgenic mice, even when compared with mice lacking apo E. These findings suggest that human apo E isoforms decrease Abeta aggregation or increase Abeta clearance relative to an environment in which mouse apo E or no apo E is present. The results may have important implications for understanding mechanisms underlying the link between apo E and AD.

Analysis of a novel mechanism of neuronal toxicity produced by an apolipoprotein E-derived peptide

The apolipoprotein E (apoE)-derived peptide (141-155)2 has a neurotoxic effect, implying that apoE itself could be a source of toxicity in Alzheimer's disease brain. We characterized the toxicity of this peptide on superior cervical ganglion (SCG) neurons and compared the death with the apoptotic death that occurs after nerve growth factor (NGF) deprivation in these cells. A dose of 10 microM apoE (141-155)2 resulted in the death of approximately 50% of the neurons within 24 h. Nuclear condensation and DNA fragmentation preceded the death. However, most inhibitors of NGF deprivation-induced death, including the caspase inhibitor Boc-aspartyl(O-methyl)fluoromethyl ketone and genetic deletion of bax-/-, had no effect on the toxicity. Inclusion of depolarizing levels of potassium did block the toxicity. Receptor-associated peptide (RAP), an antagonist for apoE receptors, did not protect cells in either SCG or hippocampal cultures. In addition, RAP had no effect on internalization of the apoE peptide. These data support the observation that apoE (141-155)2 is neurotoxic but suggest that the neurotoxicity is distinct from classical apoptosis or necrosis. Furthermore, these results indicate that the toxic effect may occur independently of members of the low-density lipoprotein receptor gene family.

Dual activation and inhibition of adenylyl cyclase by cannabinoid receptor agonists: evidence for agonist-specific trafficking of intracellular responses

Cannabinoid receptors couple to both Gs and Gi proteins and can consequently stimulate or inhibit the formation of cAMP. To test whether there is specificity among cannabinoid receptor agonists in activating Gs- or Gi-coupled pathways, the potency and intrinsic activity of various cannabinoid receptor ligands in stimulating or inhibiting cAMP accumulation were quantified. The rank order of potencies of cannabinoid receptor agonists in increasing or inhibiting forskolin-stimulated cAMP accumulation, in CHO cells expressing hCB1 receptors, was identical (HU-210 > CP-55,940 > THC > WIN-55212-2 > anandamide). However, the activities of these agonists were different in the two assays with anandamide and CP-55,940 being markedly less efficacious in stimulating the accumulation of cAMP than in inhibiting its formation. Studies examining the effects of forskolin on cannabinoid receptor mediated stimulation of adenyly cyclase also revealed differences among agonists in as much as forskolin enhanced the potency of HU-210 and CP-55,940 by approximately 100-fold but, by contrast, had no effect on the potency of WIN-55212-2 or anandamide. Taken together these findings demonstrate marked differences among cannabinoid receptor agonists in their activation of intracellular transduction pathways. This provides support for the emerging concept of agonist-specific trafficking of cellular responses and further suggests strategies for developing receptor agonists with increased therapeutic utility.

Gene therapy with HSP72 is neuroprotective in rat models of stroke and epilepsy

Brain areas damaged by stroke and seizures express high levels of the 72-kd heat shock protein (HSP72). Whether HSP72 represents merely a marker of stress or plays a role in improving neuron survival in these cases has been debated. Some induced tolerance experiments have provided correlative evidence for a neuroprotective effect, and others have documented neuroprotection in the absence of HSP72 synthesis. We report that gene transfer therapy with defective herpes simplex virus vectors overexpressing hsp72 improves neuron survival against focal cerebral ischemia and systemic kainic acid administration. HSP72 overexpression improved striatal neuron survival from 62.3 to 95.4% in rats subjected to 1 hour of middle cerebral artery occlusion, and improved survival of hippocampal dentate gyrus neurons after systemic kainic acid administration, from 21.9 to 64.4%. We conclude that HSP72 may participate in processes that enhance neuron survival during transient focal cerebral ischemia and excitotoxin-induced seizures.

Delayed repair of congenital diaphragmatic hernia with early high-frequency oscillatory ventilation during preoperative stabilization

PURPOSE

The authors reviewed their experience in the management of CDH after the introduction of early high-frequency oscillatory ventilation (HFOV) during the preoperative stabilization period and delayed CDH repair.

METHODS

This is a retrospective analysis of 24 consecutive infants with CDH treated at University of California, Irvine Medical Center (UCIMC) during a 36-month period from January 1993 to December 1996.

RESULTS

Two patients were excluded from the study: one fetus with a prenatal diagnosis was referred for fetal surgery; one infant received CDH repair at another institution 2 weeks before transfer to UCIMC. Eight (36%) infants were inborn, and nine (41%) had a prenatal diagnosis of CDH. Median gestational age was 40 weeks (range, 29 to 42 weeks). Median birth weight was 3,019 g (range, 1,205 to 4,337 g). The defect was left sided in 18 infants (86%). Twenty-one infants were intubated within 5 hours of life, 15 had an AaDO2 greater than 610, 11 had an oxygenation index greater than 40, and 11 had a pH of less than 7.2. The median ratio of pulmonary artery pressure to systemic blood pressure was 0.93 (range, 0.51 to 1.15) in 12 infants. Eighteen infants were placed on HFOV within a median of 1 hour of life. Nitric oxide was given to six infants and surfactant to eight. Four infants were referred for extracorporeal membrane oxygenation (ECMO). Repair of CDH was performed on infants at a median age of 33.5 hours (range, 5.5 to 322). Six (30%) received a prosthetic patch. Overall 18 of 22 infants survived (81%); three survivors received ECMO. Two infants of the survivor group had congenital heart anomalies: one ventricular septal defect (VSD) and one double-outlet right ventricle with a VSD. Of the four nonsurvivors, one had lethal cardiac anomalies and bilateral CDH, two had severe bilateral pulmonary hypoplasia (one received ECMO), and one infant was a 29-week premature baby who did not qualify for ECMO.

CONCLUSION

We report a survival rate of 81% (18 of 22) with the management of CDH by delayed surgical repair, early postnatal HFOV, and selective referral for ECMO.

Ligand efficacy and potency at recombinant alpha2 adrenergic receptors: agonist-mediated [35S]GTPgammaS binding

Alpha-2 adrenergic receptors (alpha2 AR) mediate incorporation of guanosine 5'-O-(gamma-thio)triphosphate ([35S]GTPgammaS) into isolated membranes via receptor-catalyzed exchange of [35S]GTPgammaS for GDP. In the current study, we used [35S]GTPgammaS incorporation to characterize the intrinsic activity and potency of agonists and antagonists at the cloned mouse alpha2a/d and human alpha2a, alpha2b, and alpha2c ARs. Full agonists increased [35S]GTPgammaS binding to membranes by 2- to 3-fold. Antagonists did not increase [35S]GTPgammaS binding but competitively inhibited agonist-stimulated [35S]GTPgammaS binding. Compounds with intrinsic activities less than that of the full agonists norepinephrine (NE) or epinephrine (EPI) were capable of antagonizing agonist-stimulated [35S]GTPgammaS binding. The agonistic properties of a number of alpha2 AR ligands were characterized at each alpha2 AR subtype. The rank order of agonist potency for selected compounds at the human receptors (with intrinsic activity compared with NE, defined as 1.0) was: alpha2a: Dexmedetomidine (0.73) > guanabenz (0.38) > UK-14304 (1.02) > clonidine (0.32) > ST-91 (0.63) > NE (1.00). alpha2b: Dexmedetomidine (1.10) > clonidine (0.18) > guanabenz (0.71) > NE (1.00) > ST-91 (0.44) > UK-14304 (0.59). alpha2c: Dexmedetomidine (1.03) > NE (1.00) > UK-14304 (0.75) > ST-91 (0.32) > or = clonidine (0.23) >> guanabenz (0). This report provides a functional characterization of adrenergic receptor ligands at human and mouse alpha2a/d AR. It also illustrates the utility of [35S]GTPgammaS incorporation as a functional marker of receptor activation.

Defective herpes simplex virus vectors expressing the rat brain stress-inducible heat shock protein 72 protect cultured neurons from severe heat shock

Recently, preinduction of the heat shock response has been shown to protect CNS neurons undergoing various stressful insults, e.g., heat, ischemia, or exposure to excitotoxins. However, it is not known which of the proteins induced by the heat shock response mediate the protective effects. Previous correlative evidence points to a role for the highly stress-induced 72-kDa heat shock protein (hsp72). However, it is not known whether hsp72 expression alone can protect against a range of acute neuronal insults. We constructed a herpes simplex virus-1 vector carrying the rat brain stress-inducible hsp72 gene and the Escherichia coli lacZ (marker) gene. Infection with the vector caused hippocampal neurons to coexpress hsp72 and beta-galactosidase. Infection with a control vector led to marker gene expression only. Overexpression of hsp72 protected cultured hippocampal neurons against a heat shock but not against the metabolic toxin 3-nitropropionic acid or the excitotoxin glutamate. This is the first published report of protection following heat shock protein transfection in CNS neurons.

Basal and meal-stimulated colonic absorption

PURPOSE

Few quantitative experiments evaluating colonic absorption of water and electrolytes have been performed using an awake, conscious animal model. The purpose of these experiments was to develop this type of model and evaluate both basal and meal-stimulated colonic absorption of water and electrolytes.

METHODS

Canine Thiry-Vella fistulas were created using a 20 cm segment of distal colon under general anesthesia. Colonic absorption studies were performed using infusion of the Thirty-Vella fistulas with a buffer solution containing [14C]polyethylene glycol. Electrolyte analysis and concentration of radioactivity in the effluent were obtained and used to calculate the net flux of water, sodium, and chloride. Each study consisted of an one-hour basal period and a three-hour experimental period divided into two groups. Group 1 received no meal. Group 2 orally ingested a mixed meal at the completion of the basal hour.

RESULTS

In the basal state, water and electrolytes are absorbed from the distal colon at a steady and constant rate. An orally ingested meal produces a statistically significant increase in the rate of absorption, independent of direct colonic luminal contact with the nutrients of the meal given.

CONCLUSIONS

These studies demonstrate an in vivo quantitative and qualitative measure of mammalian colonic water and electrolyte absorption. An increase in absorption rate occurs in response to a meal that is probably the result of an unidentified neural or humoral signal.

Transposon mutagenesis and cloning of the genes encoding the enzymes of fengycin biosynthesis in Bacillus subtilis

A total of 20 Bacillus subtilis F29-3 mutants defective in fengycin biosynthesis was obtained by Tn917 mutagenesis. Cloning and mapping results showed that the transposon in these mutants was inserted in eleven different locations on the chromosome. We were able to use the chromosomal sequence adjacent to the transposon as a probe to screen for cosmid clones containing the fengycin biosynthesis genes. One of the clones obtained, pFC660, was 46 kb long. Eight transposon insertion sites were mapped within this plasmid. Among the eleven different mutants analyzed, four mutants had Tn917 inserted in regions which encoded peptide sequences similar to part of gramicidin S synthetase, surfactin synthetase, and tyrocidine synthetase. Our results suggest that fengycin is synthesized nonribosomally by the multienzyme thiotemplate mechanism.

Construction of Tn917ac1, a transposon useful for mutagenesis and cloning of Bacillus subtilis genes

A Tn917 derivative was constructed for the purposes of mutagenesis and cloning of Bacillus subtilis genes. This transposon, Tn917ac1 (4.6 kb), consisted of terminal inverted repeats of Tn917, the res sequence, a ColE1 origin of replication (ori) and two drug-resistance genes. The plasmid carrying this transposon, named pD917, contained the erm-tnpR-tnpA gene cluster of Tn917 and a temperature-sensitive ori of pE194. For the purpose of mutagenesis, transposition of Tn917ac1 was induced by culturing strains harboring pD917 in a medium containing a low concentration of erythromycin. Cells with a Tn917ac1 insertion in the chromosome were selected on agar containing chloramphenicol after heat treatment to eliminate the plasmidic form of pD917. DNA fragments adjacent to Tn917ac1 could be cloned by restriction digestion of the chromosomal DNA and by transforming the self-ligated restriction fragments into Escherichia coli. Sequence analysis revealed that Tn917ac1 was integrated into the chromosome of B. subtilis by transposition in a recE strain and by transposition or integration of pD917 in a wild-type strain. Tn917ac1 has been demonstrated to be useful for mutating and cloning of the genes involved in the biosynthesis of fengycin in B. subtilis F29-3.

Usefulness and limitations of transesophageal echocardiography in the assessment of proximal coronary artery stenosis

To assess the usefulness of transesophageal echocardiography in the evaluation of proximal coronary artery stenosis, 111 consecutive patients (mean age 61 years) who had intraoperative transesophageal echocardiography and coronary angiography within 1 week of surgery were studied. Transesophageal echocardiography visualized the entire length of the left main artery (0.2 to 2.2 cm, mean 0.93), 0.2 to 2.2 cm of the proximal left anterior descending artery and 0.1 to 3.4 cm of the proximal left circumflex artery in 103 patients (93%) and 0.1 to 4.6 cm of the proximal right coronary artery in 55 patients (49%). In the coronary artery segments visualized by echocardiography and compared with the corresponding angiographic segments, transesophageal echocardiography correctly identified 23 (96%) of 24 left main stenoses, 11 (78%) of 14 stenoses involving the left anterior descending artery, 6 (75%) of 8 left circumflex stenoses and all 7 stenoses (100%) of the right coronary artery. In all seven patients with ostial stenosis (left main artery in five and right coronary artery in two), the condition was correctly diagnosed by this technique. The sensitivity and specificity of transesophageal echocardiography in the overall evaluation of proximal coronary artery stenosis as customarily defined by angiography were 96% and 99% for the left main artery, 48% and 99% for the left anterior descending artery, 67% and 100% for the left circumflex artery and 37% and 100% for the right coronary artery, respectively. The distance of the stenotic lesion from the origin of the vessel by transesophageal echocardiography also correlated well with that measured by angiography (r = 0.63 to 0.99).(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple secundum type atrial septal defects: identification by transthoracic color Doppler echocardiography

This case illustrates the utility of two-dimensional color Doppler echocardiography in detecting and localizing multiple atrial septal defects not consistently demonstrated by standard two-dimensional echocardiography.

Histamine regulation of adenylyl cyclase of enriched rat gastric parietal cells

Rat gastric parietal cells were isolated to 90% or greater purity by discontinuous gradient ultracentrifugation in sucrose-Ficoll. Adenylyl cyclase activity was initiated by histamine in the presence of 5'-guanylyl imidodiphosphate, but not by pentagastrin or acetylcholine. The concentration of histamine needed for half-maximal activation of adenylyl cyclase was 38 microM. The histamine H2-receptor antagonist, metiamide, inhibited histamine (100 microM) activation with a Ki of 0.9 microM. The effects of other histamine agonists and antagonists suggest that presence of H2-type histaminic receptors on parietal cells. Adenylyl cyclase activity was also stimulated by isoproterenol, norepinephrine, and epinephrine, but not by methoxamine. Half-maximal activation by isoproterenol occurred at 0.5 microM. Propranolol, but not phentolamine, prevented activation by these agents, indicating the presence of beta-adrenergic receptors on parietal cells. Prostaglandins E2 stimulated adenylyl cyclase of partially purified (30%), but not the enriched (90%), parietal cell populations.

Rat gastric mucosal adenylyl cyclase

Prostaglandin E1, epinephrine, secretin, and glucagon are known inhibitors of gastric acid secretion, and each agent stimulated mucosal membrane (600 X g pellet) adenylyl cyclase activity from the corpus of the rat stomach. This adenylyl cyclase activity was also stimulated by 5'-guanylyl-imidodiphosphate and sodium fluoride but not by guanosine-5'-triphosphate. By contrast, the gastric acid secretagogues, pentagastrin, histamine, and carbachol, had no effect on basal or prostaglandin E1-stimulated mucosal adenylyl cyclase activity. Most of the sodium fluoride- and hormone-stimulated adenylyl cyclase of the corpus mucosa was contained in the 600 X g membrane fraction. The enzyme exhibited Michaelis-Menten kinetics with respect to the concentration of ATP, with an apparent Km of 0.25 mM. Histamine did not stimulate rat mucosal adenylyl cyclase activity under a variety of conditions, but did stimulate the same enzyme in guinea pig gastric fundic mucosa, an enzyme also activated by prostaglandin E1. These studies do not support the hypothesis that cyclic AMP mediates the actions of gastric acid secretagogues on the parietal cell in the rat.

Activation of rat gastric mucosal adenylyl cyclase by secretory inhibitors

Prostaglandin (PG) E1, E2, A1, and A2 stimulated rat gastric corpus mucosal membrane adenylyl cyclase activity. PGE1 (Kalpha congruent to 8 muM) affected the maximum velocity but not the affinity of the enzyme for ATP and maximum PGE1 activation was not affected by histamine H1 or H2 receptor antagonists. 5'-Guanylyl-diphosphoimide (Gpp(NH)p), but not GTP, stimulated both the basal and PGE1-stimulated adenylyl cyclase activities, although the percentage stimulation by maximal PGE was the same with or without Gpp(NH)p. NaF stimulation was also additive to that of PGE1. Secretin also stimulated gastric mucosal adenylyl cyclase activity (Kalpha congruent to 30 nM). Maximal secretin activation was not additive to that of PGE1, suggesting a coupling to the same adenylyl cyclase catalytic site. These studies suggest that mucosal membranes may contain beta-adrenergic receptors. The adenylyl cyclase activating agents used in this study, PGE1, secretin, and the catecholamines, are all known inhibitors of gastric acid secretion, suggesting a possible involvement of cyclic AMP in the inhibition of acid secretion in the rat stomach.