Dual adaptation and adaptive generalization of the human vestibulo-ocular reflex

In two experiments, we examined the possibility that the human vestibulo-ocular reflex (VOR) is subject to dual adaptation (the ability to adapt to a sensory rearrangement more rapidly and/or more completely after repeated experience with it) and adaptive generalization (the ability to adapt more readily to a novel sensory rearrangement as a result of prior dual adaptation training). In Experiment 1, the subjects actively turned the head during alternating exposure to a visual-vestibular rearrangement (target/head gain = 0.5) and the normal situation (target/head gain = 0.0). These conditions produced both adaptation and dual adaptation of the VOR but no evidence of adaptive generalization when tested with a target/head gain of 1.0. Experiment 2, in which exposure to the 0.5 gain entailed externally controlled (i.e., passive) whole body rotation, resulted in VOR adaptation but no dual adaptation. As in Experiment 1, no evidence of adaptive generalization was found.

Synthetic, implantable polymers for local delivery of IUdR to experimental human malignant glioma

PURPOSE

Recently, polymeric controlled delivery of chemotherapy has been shown to improve survival of patients with malignant glioma. We evaluated whether we could similarly deliver halogenated pyrimidines to experimental intracranial human malignant glioma. To address this issue we studied the in vitro release from polymers and the in vivo drug delivery of IUdR to experimental human U251 glioblastoma xenografts.

METHODS AND MATERIALS

In vitro: To measure release, increasing (10%, 30%, 50%) proportions of IUdR in synthetic [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) polymer discs were serially incubated in buffered saline and the supernatant fractions were assayed. In vivo: To compare local versus systemic delivery, mice bearing flank xenografts had intratumoral or contralateral flank IUdR polymer (50% loading) treatments. Mice bearing intracranial (i.c.) xenografts had i.c. versus flank IUdR polymer treatments. Four or 8 days after implantation of polymers, mice were sacrificed and the percentage tumor cells that were labeled with IUdR was measured using quantitative microscopic immunohistochemistry.

RESULTS

In vitro: Increasing percentage loadings of IUdR resulted in higher percentages of release: 43.7 + 0.1, 70.0 + 0.2, and 90.2 + 0.2 (p < 0.001 ANOVA) for the 10%, 30%, and 50% loadings, respectively. In vivo: For the flank tumors, both the ipsilateral and contralateral IUdR polymers resulted in similarly high percentages labeling of the tumors versus time. For the ipsilateral IUdR polymers, the percentage of tumor cellular labeling after 4 days versus 8 days was 45.8 +/- 7.0 versus 40.6 +/- 3.9 (p = NS). For the contralateral polymer implants, the percentage of tumor cellular labeling were 43.9 +/- 10.1 versus 35.9 +/- 5.2 (p = NS) measured 4 days versus 8 days after implantation. For the i.c. tumors treated with extracranial IUdR polymers, the percentage of tumor cellular labeling was low: 13.9 +/- 8.8 and 11.2 +/- 5.7 measured 4 and 8 days after implantation. For the i.c. tumors having the i.c. IUdR polymers, however, the percentage labeling was comparatively much higher: 34.3 +/- 4.9 and 35.3 +/- 4.0 on days 4 and 8, respectively. For the i.c. tumors, examination of the percentage cellular labeling versus distance from the implanted IUdR polymer showed that labeling was highest closest to the polymer disc.

CONCLUSION

Synthetic, implantable biodegradable polymers provide the local, controlled release of IUdR and result in the high, local delivery of IUdR to experimental intracranial human malignant glioma. This technique holds promise for the local delivery of IUdR for radiosensitization of human brain tumors.

A role for the p38 mitogen-activated protein kinase/Hsp 27 pathway in cholecystokinin-induced changes in the actin cytoskeleton in rat pancreatic acini

Cholecystokinin (CCK) and other pancreatic secretagogues have recently been shown to activate signaling kinase cascades in pancreatic acinar cells, leading to the activation of extracellular signal-regulated kinases and Jun N-terminal kinases. We now show the presence of a third kinase cascade activating p38 mitogen-activated protein (MAP) kinase in isolated rat pancreatic acini. CCK and osmotic stress induced by sorbitol activated p38 MAP kinase within minutes; their effects were dose-dependent, with maximal activation of 2.8- and 4.4-fold, respectively. The effects of carbachol and bombesin on p38 MAP kinase activity were similar to those of CCK, whereas phorbol ester, epidermal growth factor, and vasoactive intestinal polypeptide stimulated p38 MAP kinase by 2-fold or less. Both CCK and sorbitol also increased the tyrosyl phosphorylation of p38 MAP kinase. Using the specific inhibitor of p38 MAP kinase, SB 203580, we found that p38 MAP kinase activity was required for MAP kinase-activated protein kinase-2 activation in pancreatic acini. SB 203580 reduced the level of basal phosphorylation and blocked the increased phosphorylation of Hsp 27 after stimulation with either CCK or sorbitol. CCK treatment induced an initial rapid decrease in total F-actin content of acini, followed by an increase after 40 min. Preincubation with SB 203580 significantly inhibited these changes in F-actin content. Staining of the actin cytoskeleton with rhodamine-conjugated phalloidin and analysis by confocal fluorescence microscopy showed disruption of the actin cytoskeleton after 10 and 40 min of CCK stimulation. Pretreatment with SB 203580 reduced these changes. These findings demonstrate that the activation of p38 MAP kinase is involved not only in response to stress, but also in physiological signaling by gastrointestinal hormones such as CCK, where activation of Gq-coupled receptors stimulates a cascade in which p38 MAP kinase activates MAP kinase-activated protein kinase-2, resulting in Hsp 27 phosphorylation. Activation of p38 MAP kinase, most likely through phosphorylation of Hsp 27, plays a role in the organization of the actin cytoskeleton in pancreatic acini.

Dosimetric properties of a novel brachytherapy balloon applicator for the treatment of malignant brain-tumor resection-cavity margins

PURPOSE

This paper characterizes the dosimetric properties of a novel balloon brachytherapy applicator for the treatment of the tissue surrounding the resection cavity of a malignant brain tumor.

METHODS AND MATERIALS

The applicator consists of an inflatable silicone balloon reservoir attached to a positionable catheter that is intraoperatively implanted into the resection cavity and postoperatively filled with a liquid radionuclide solution. A simple dosimetric model, valid in homogeneous media and based on results from Monte Carlo photon-transport simulations, was used to determine the dosimetric characteristics of spherical geometry balloons filled with photon-emitting radionuclide solutions. Fractional depth-dose (FDD) profiles, along with activity densities, and total activities needed to achieve specified dose rates were studied as a function of photon energy and source-containment geometry. Dose-volume histograms (DVHs) were calculated to compare idealized balloon-applicator treatments to conventional 125I seed volume implants.

RESULTS

For achievable activity densities and total activities, classical low dose rate (LDR) treatments of residual disease at distances of up to 1 cm from the resection cavity wall are possible with balloon applicators having radii between 0.5 cm and 2.5 cm. The dose penetration of these applicators increases approximately linearly with balloon radius. The FDD profile can be made significantly more or less penetrating by combining selection of radionuclide with source-geometry manipulation. Comparisons with 125I seed-implant DVHs show that the applicator can provide a more conformal therapy with no target tissue underdosing, less target tissue overdosing, and no healthy tissue "hot spots;" however, more healthy tissue volume receives a dose of the prescribed dosage or less.

CONCLUSIONS

This device, when filled with 125I solution, is suitable for classical LDR treatments and may be preferable to 125I interstitial-seed implants in several respects. Manipulation of the dosimetric properties of the device can improve its characteristics for brain tumor treatment and may make it suitable for boosting the lumpectomy margins in conservative breast cancer treatment.

Regulation of protein synthesis by cholecystokinin in rat pancreatic acini involves PHAS-I and the p70 S6 kinase pathway

BACKGROUND & AIMS

Cholecystokinin (CCK) stimulates protein synthesis in pancreatic acini at the translational level, although the signaling mechanisms involved remain uncharacterized. Two intermediates controlling translation are p70 S6 kinase and PHAS-I. We previously showed that CCK activates p70 S6K in pancreatic acini through phosphatidylinositol 3-kinase (PI 3K). In the present study we investigated the role of PI 3K, p70 S6K, and PHAS-I in mediating CCK-stimulated protein synthesis.

METHODS

Protein synthesis was measured by [35S]methionine incorporation into pancreatic protein using acini from rats with streptozotocin-induced diabetes. p70 S6 K activity was measured. PHAS-I was identified by Western analysis. PHAS-I/eIF-4E association was measured as the amount of PHAS-I recovered after purification of translation factor eIF-4E by 7-methyl guanosine triphosphate-Sepharose.

RESULTS

Rapamycin and PI 3K inhibitors, wortmannin and LY294002, blocked CCK-stimulated p70 S6K activity. Rapamycin inhibited basal protein synthesis and blocked the increase to all CCK concentrations. Wortmannin and LY294002 dose-dependently inhibited basal and CCK-stimulated protein synthesis and also blocked insulin-stimulated protein synthesis. CCK dose-dependently increased PHAS-I phosphorylation via a rapamycin- and LY294002-sensitive pathway and decreased the amount of PHAS-I associated with eIF-4E. Rapamycin and LY294002 eliminated this effect of CCK.

CONCLUSIONS

CCK stimulation of protein synthesis in pancreatic acini is sensitive to rapamycin and PI 3K inhibitors and involves PHAS-I phosphorylation and its association with eIF-4E.

Effect of N-methyl-D-aspartate receptor blockade on the control of cerebral O2 supply/consumption balance during hypoxia in newborn pigs

Using dizocilpine (MK-801), we tested the hypothesis that N-methyl-D-aspartate (NMDA) receptors are important controllers of cerebral O2 supply/consumption balance in newborn piglets both during normoxia and hypoxia. Twenty-five 2 to 7-day-old piglets were anesthetized and divided into four groups: (1) Normoxia (n = 6), (2) Normoxia + MK-801 (n = 6), (3) Hypoxia (n = 6), and (4) Hypoxia + MK-801 (n = 7). Regional cerebral blood flow (rCBF) in ml/min/100 g was measured using 14C-iodoantipyrine, and we determined arterial and venous O2 saturations by microspectrophotometry, calculating cerebral O2 consumption (VO2) in ml O2/min/100 g in the cortex, hypothalamus and pons. MK-801 did not significantly affect regional VO2 or rCBF in normoxic piglets. Hypoxia resulted in an increase in local rCBF compared to controls: from 41 +/- 6 to 103 +/- 18 in the cortex; 34 +/- 7 to 101 +/- 20 in the hypothalamus; and 45 +/- 10 to 95 +/- 11 in the pons. Pretreatment with MK-801 abolished this hypoxic flow effect in the cortex (51 +/- 2) and hypothalamus (49 +/- 5), but not in the pons (91 +/- 17). Similar results were observed for VO2 with control values of 1.9 +/- 0.3, 1.6 +/- 0.2 and 2.1 +/- 0.3 for the cortex, hypothalamus and pons respectively. Hypoxia resulted in an increase in the VO2 to 3.9 +/- 0.4 (cortex), 3.8 +/- 0.6 (hypothalamus) and 3.9 +/- 0.8 (pons). Pretreatment with MK-801 prior to hypoxia abolished these effects in the cortex (2.1 +/- 0.2) and hypothalamus (2.1 +/- 0.2), but not in the pons (2.9 +/- 0.2). These findings suggest that NMDA receptors may play a role in the control of cerebral metabolism during hypoxia in this immature porcine model.

Purification and characterization of a novel physiological substrate for calcineurin in mammalian cells

Although the calcium/calmodulin-regulated protein phosphatase calcineurin has been shown to play a role in a number of intracellular processes, relatively few of the downstream phosphoproteins that are dephosphorylated by this enzyme in cells have been described. Calcineurin was previously shown to play a role in amylase secretion by rat pancreatic acinar cells and to specifically dephosphorylate a 24-kDa cytosolic protein. The present study describes the purification and characterization of this novel phosphoprotein, termed CRHSP-24 (calcium-regulated heat-stable protein with a molecular mass of 24 kDa). Microgram quantities of CRHSP-24 were purified from a large-scale rat pancreas preparation in a procedure involving heat and acid precipitation, anion-exchange chromatography, preparative electrophoresis, electroelution, and two-dimensional electrophoresis. Internal amino acid sequence was obtained from two peptides following trypsin digestion and high pressure liquid chromatography. Both sequences matched with 100% identity nucleotide sequences of expressed sequence tags from human placenta and rat PC-12 cells. Two CRHSP-24 transcripts of 0.7 and 2. 9 kilobases were detected in multiple rat tissues by Northern analysis, whereas a single 24-kDa protein was observed by Western blotting. The CRHSP-24 protein is 147 amino acids in length, is composed of nearly 14% proline, and is phosphorylated entirely on serine residues. Western analysis and 32P metabolic labeling of acini revealed CRHSP-24 to be maximally phosphorylated in control cells and to undergo a rapid sustained dephosphorylation on at least 3 serine residues in response to calcium-mobilizing stimuli. Dephosphorylation of CRHSP-24 was completely inhibited by pretreatment of acini with cyclosporin A or FK506. Furthermore, the inhibitory effects of FK506 were blocked by excess rapamycin. The ubiquitous expression of CRHSP-24 in rat tissues suggests that this novel calcineurin substrate plays a common role in calcium-mediated signal transduction.

Nitric oxide regulates cyclic GMP-dependent protein kinase phosphorylation in rat brain

Nitric oxide (NO) acts via soluble guanylyl cyclase to increase cyclic GMP (cGMP), which can regulate various targets including protein kinases. Western blotting showed that type II cGMP-dependent protein kinase (cGK II) is widely expressed in various brain regions, especially in the thalamus. In thalamic extracts, the phosphorylation of several proteins, including cGK II, was increased by exogenous NO or cGMP. In vivo pretreatment with a NO synthase inhibitor reduced the phosphorylation of cGK II, and this could be reversed by exogenous NO or cGMP. Conversely, brainstem electrical stimulation, which enhances thalamic NO release, caused a NO synthase-dependent increase in the phosphorylation of thalamic cGK II. These results indicate that endogenous NO regulates cGMP-dependent protein phosphorylation in the thalamus. The activation of cGKII by NO may play a role in thalamic mechanisms underlying arousal.

Constitutional balanced translocations in alveolar rhabdomyosarcoma

Chromosomal analysis of tumor tissue from two children with alveolar rhabdomyosarcoma revealed t(1;5)(q32;q31) and t(1;22)(q21;q11.2) in all metaphases examined, respectively. Peripheral blood lymphocytes carried the same cytogenetic abnormality as that of the tumor cells in both patients. Parental lymphocytes were karyotypically normal in the patient with t(1;22), indicating a de novo constitutional translocation, but t(1;5) was paternally inherited in the other patient. The presence of constitutional translocations in these two children might have contributed to the development of alveolar rhabdomyosarcoma.

Effect of moisture protective coatings on the strength of a modern metal-reinforced glass-ionomer cement

The strength of a modern, low metal:glass ratio, metal-reinforced glass-ionomer cement was measured evaluating a number of protective barriers: one light-cured resin, two solvent-based dental varnishes and petroleum jelly. The cement was exposed to water at 10 and 60 min from start of mix. The results obtained with these protecting agents were compared with those obtained where no protection was applied. A comparison of uniaxial flexural strength and biaxial flexural strength showed the latter to be more discriminating. Proprietary dental varnishes were superior to petroleum jelly, producing similar strengths of 50 MPa. Petroleum jelly was, however, preferable to no protection. Moisture protection during the first 30 min was found to be beneficial, thereafter no further strength increase was found. A second material, a cement which has a high metal:glass ratio, was found to be more moisture resistant but weaker in strength than the modern material, with a biaxial strength of 39 MPa.

The contribution of subtle oocyte or sperm dysfunction affecting fertilization in endometriosis-associated or unexplained infertility: a controlled comparison with tubal infertility and use of donor spermatozoa

This study aims to determine the relative contribution of oocyte and/or sperm dysfunction to the reduction of fertilization rates in vitro in cases of minor endometriosis and prolonged unexplained infertility. The results of in-vitro fertilization (IVF) treatment with ovarian stimulation have been compared between couples with the above conditions and women with tubal infertility (as control for oocyte function) and the use of donor spermatozoa (as control for sperm function). Fertilization and cleavage rates using husband's spermatozoa were significantly reduced in endometriosis couples (56%, n = 194, P < 0.001) and further significantly reduced in couples with unexplained infertility (52%, n = 327, P < 0.001) compared with tubal infertility (60%, n = 509). Using donor spermatozoa the rates were the same as using husband's spermatozoa in tubal infertility (61%, n = 27) or endometriosis (55%, n = 21) but significantly though only partly improved with unexplained infertility (57%, n = 60, P < 0.02). In unexplained infertility, a significantly increased proportion of couples experienced complete failure of fertilization and cleavage in a cycle (5-6% versus 2-3%). However, complete failure was not usually repetitive, and the affected couples did not account for the overall reduction in fertilization and cleavage rates, which remained significantly lower in the rest of the unexplained and endometriosis groups. Implantation and pregnancy rates appeared similar in all groups. The benefit of IVF treatment in cases of minor endometriosis and prolonged unexplained infertility is due to superabundance of oocytes obtained by stimulation. The reduction in natural fertility associated with endometriosis appears to be at least partly due to a reduced fertilizing ability of the oocyte. In unexplained infertility, there is distinct impairment due to otherwise unsuspected sperm dysfunction but probably also oocyte dysfunction.

7-Oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridines as novel inhibitors of human eosinophil phosphodiesterase

High-throughput file screening against inhibition of human lung PDE4 led to the discovery of 3-ethyl-1-(4-fluorophenyl)-6-phenyl-7-oxo-4, 5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine (11) as a novel PDE4 inhibitor. Subsequent SAR development, using an eosinophil PDE assay, led to analogues up to 50-fold more potent than 11 with IC50 values of 0.03-1.6 microM. One such compound, CP-220,629 (22) (IC50 = 0.44 microM), was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 2.0 mg/kg, po) and demonstrated a significant reduction in eosinophil (55%), neutrophil (65%), and IL-1beta (82%) responses to antigen challenge in atopic monkeys (10 mg/kg, po).

Effect of interstitial and/or systemic delivery of tirapazamine on the radiosensitivity of human glioblastoma multiforme in nude mice

The purpose of this study was to investigate the feasibility and the efficacy of administering tirapazamine by a slow-releasing polymer disc that was implanted interstitially into a U251 (human glioblastoma multiforme) tumor grown in nude mice. Tumor-bearing animals, with a tumor nodule 0.8 cm3 in size, were distributed to groups receiving combinations of empty or drug-containing polymer implants in the tumor or contralateral leg, intraperitoneal (i.p.) drug, and/or irradiation. The drug (i.p.) alone (14 mg/kg x6) or in combination with tumor drug implant (2 mg) did not significantly increase the tumor volume doubling time compared to that of control animals. Given with 12 Gy of irradiation in twice a day 2-Gy fractions, combined i.p. drug and tumor drug implant significantly delayed tumor growth compared to irradiation alone, which was not achieved with either drug treatment alone added to irradiation. Toxicity, as manifested by transient weight loss, was primarily seen in animals receiving radiation and i.p. tirapazamine. These results indicated that a slow-releasing tirapazamine disc can be produced and the addition of an interstitially implanted tirapazamine disc further increased the effectiveness of i.p. tirapazamine.

Interindividual variation in the metabolic activation of heterocyclic amines and their N-hydroxy derivatives in primary cultures of human mammary epithelial cells

The heterocyclic amines, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are pyrolysis products formed when meat is cooked and are rodent mammary carcinogens. They are thought to be metabolically activated by N-hydroxylation, catalysed by cytochrome P450 (CYP), followed by O-acetylation catalysed by N-acetyltransferases. Primary cultures of human mammary epithelial cells (HMECs) prepared from up to 26 individuals for each compound, were treated with IQ, MeIQ, or PhIP (500 microM) or with N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP) or N-hydroxy-2-amino-3-methylimidazo[4,5-f]quinoline (N-OH-IQ) (20 microM) and the levels of adduct formation in their DNA analysed by 32P-post-labelling. In order to investigate whether pharmacogenetic polymorphisms influence DNA adduct formation, the NAT2 genotype of each individual was determined by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method that distinguishes between the wild-type and four variant alleles. Presence of two variant alleles designates a slow NAT2 acetylator, whereas individuals with one or two wild-type alleles are designated fast NAT2 acetylators. Interindividual variations in total DNA adduct levels ranged for IQ from 0.64-63.1 DNA adducts per 10(8) nucleotides (mean 7.80), for MeIQ from 1.99-17.8 (mean 6.63), for PhIP from 0.13-4.0 (mean 0.96), for N-OH-PhIP from 6.32-497 (mean 176) and for N-OH-IQ from 0.92-30.6 (mean 9.24). The higher adduct levels observed in cells treated with the N-OH metabolites suggests that N-hydroxylation is the rate-limiting step in HMECs and this may be due to low CYP levels. In contrast, the Phase II reaction catalysed by N-acetyltransferases is probably the major step in the metabolic activation of heterocyclic amines that occurs in the breast. Higher mean levels of heterocyclic amine-DNA adduct formation were detected in the cells of NAT2 fast acetylators compared with slow acetylators, with mean adduct levels per 10(8) nucleotides following IQ treatment, of 12.74 and 3.57 respectively, following PhIP treatment, of 1.20 and 0.74, respectively, following MeIQ treatment, of 7.90 and 5.08, respectively and following N-OH-PhIP-treatment, of 243.1 and 130.0, respectively. However, due to the large variations in adduct levels, these differences in mean values were not statistically significant with the limited number of individuals studied. This appears to be the first pilot study to demonstrate interindividual variations in the metabolic activation of heterocyclic amines and their metabolic intermediates in primary cultures of HMECs in vitro.

Antibodies to recombinant Clostridium difficile toxins A and B are an effective treatment and prevent relapse of C. difficile-associated disease in a hamster model of infection

Clostridium difficile causes antibiotic-associated diarrhea and colitis in humans through the actions of toxin A and toxin B on the colonic mucosa. At present, broad-spectrum antibiotic drugs are used to treat this disease, and patients suffer from high relapse rates after termination of treatment. This study examined the role of both toxins in pathogenesis and the ability of orally administered avian antibodies against recombinant epitopes of toxin A and toxin B to treat C. difficile-associated disease (CDAD). DNA fragments representing the entire gene of each toxin were cloned, expressed, and affinity purified. Hens were immunized with these purified recombinant-protein fragments of toxin A and toxin B. Toxin-neutralizing antibodies fractionated from egg yolks were evaluated by a toxin neutralization assay in Syrian hamsters. The carboxy-terminal region of each toxin was most effective in generating toxin-neutralizing antibodies. With a hamster infection model, antibodies to both toxins A and B (CDAD antitoxin) were required to prevent morbidity and mortality from infection. In contrast to vancomycin, CDAD antitoxin prevented relapse and subsequent C. difficile reinfection in the hamsters. These results indicate that CDAD antitoxin may be effective in the treatment and management of CDAD in humans.

Comparison of North American Symptomatic Carotid Endarterectomy Trial and population-based outcomes for carotid endarterectomy

PURPOSE

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) advocated the use of carotid endarterectomy (CEA) for transient ischemic attacks (TIAs), nondisabling strokes, and ipsilateral high-grade stenosis in highly selected patients. Whether similar results are achieved when CEA is applied to an entire geographically defined population is unknown but important if the NASCET recommendations are to be applied broadly to all community patients.

METHODS

To determine the survival rate to ipsilateral stroke after CEA for all symptomatic patients in a defined population, we reviewed the medical records of all patients residing in Olmsted County, Minn. (approximately 100,000), who underwent a CEA for TIA or nondisabling stroke between 1970 and 1995. Their outcomes were compared with the NASCET results.

RESULTS

In the community of Olmsted County, 297 patients (108 women and 189 men) underwent 322 CEAs during the study period. TIAs or nondisabling stroke was the indication in 254 patients (86%), whereas the remaining 14% had asymptomatic stenosis. After CEA for symptomatic lesions, survival rate free of ipsilateral stroke was 97% at 2 years, 93% at 5 years, and 92% at 10 years. These results are similar to the NASCET survival rates free of ipsilateral stroke at 2 years (91%). However, the 30-day postoperative stroke rate for patients older than 80 years was significantly higher than that for patients younger than 80 years.

CONCLUSIONS

When the NASCET results are compared with a population-based experience in which all symptomatic patients undergoing CEA were analyzed, the early outcomes were similar. Our population-based data also document the remarkably durable long-term results of CEA in preventing stroke and present another benchmark for carotid stent angioplasty.

Benzodiazepine receptor antagonists modulate the actions of ethanol in alcohol-preferring and -nonpreferring rats

The pyrazoloquinoline CGS 8216 (2-phenylpyrazolo-[4,3-c]-quinolin-3 (5H)-one, 0.05-2 mg/kg) and the beta-carboline ZK 93426 (ethyl-5-isopropyl-4-methyl-beta-carboline-3-carboxylate, 1-10 mg/kg) benzodiazepine receptor antagonists were evaluated for their capacity to modulate the behavioral actions of ethanol in alcohol preferring and -nonpreferring rats. When alcohol-preferring rats were presented with a two-bottle choice test between ethanol (10% v/v) and a saccharin (0.0125% g/v) solution, both antagonists dose-dependently reduced intake of ethanol by 35-92% of control levels on day 1 at the initial 15 min interval of the 4 h limited access. Saccharin drinking was suppressed only with the highest doses. CGS 8216 (0.25 mg/kg) and ZK 93426 (4 mg/kg) unmasked the anxiolytic effects of a hypnotic ethanol dose (1.5 g/kg ethanol) on the plus maze test in alcohol-preferring rats, but potentiated the ethanol-induced suppression in alcohol-nonpreferring rats. CGS 8216 (0.25 mg/kg) and ZK 93426 (4 mg/kg) attenuated the ethanol (0.5 and 1.5 g/kg)-induced suppression in the open field in alcohol-nonpreferring rats; however, CGS 8216 potentiated the depressant effects of the lower ethanol dose (0.5 g/kg) in alcohol-preferring rats. These findings provide evidence that benzodiazepine receptor antagonists may differentially modulate the behavioral actions of ethanol in alcohol-preferring and-nonpreferring rats. It is possible that the qualitative pharmacodynamic differences seen in the present study may be related to selective breeding for alcohol preference. The findings indicate the potential for development of receptor specific ligands devoid of toxic effects which may be useful in the treatment of alcohol abuse and alcoholism.

Overexpression of Rab3D enhances regulated amylase secretion from pancreatic acini of transgenic mice

Rab3D, a member of the ras-related GTP-binding protein Rab family, is localized to secretory granules of various exocrine tissues such as acinar cells of the pancreas, chief cells of the stomach, and parotid and lacrimal secretory cells. To elucidate the function of Rab3D in exocytosis, we have generated transgenic mice that over-express Rab3D specifically in pancreatic acinar cells. Hemagglutinin-tagged Rab3D was localized to zymogen granules by immunohistochemistry, and was shown to be present on zymogen granule membranes by Western blotting; both results are similar to previous studies of endogenous Rab3D. Secretion measurements in isolated acinar preparations showed that overexpression of Rab3D enhanced amylase release. Amylase secretion from intact acini of transgenic mice 5 min after 10 pM cholecystokinin octapeptide (CCK) stimulation was enhanced by 160% of control. In streptolysin-O-permeabilized acini of transgenic mice, amylase secretion induced by 100 microM GTP-gamma-S was enhanced by 150%, and 10 microM Ca2+-stimulated amylase secretion was augmented by 206% of that of the control. To further elucidate Rab3D involvement in stimulus-secretion coupling, we examined the effect of CCK on the rate of GTP binding to Rab3D. Stimulation of permeabilized acini with 10 pM CCK increased the incorporation of radiolabeled GTP into HA-tagged Rab3D. These results indicate that overexpression of Rab3D enhances secretagogue-stimulated amylase secretion through both calcium and GTP pathways. We conclude that Rab3D protein on zymogen granules plays a stimulatory role in regulated amylase secretion from pancreatic acini.

Stimulation of both CCK-A and CCK-B receptors activates MAP kinases in AR42J and receptor-transfected CHO cells

It was recently found that cholecystokinin (CCK) activates mitogen-activated protein kinases (MAPK) in isolated rat pancreatic acini. The present study evaluates whether one or both types of CCK receptors are capable of MAPK activation in pancreatic AR42J acinar cells as well as CHO cells transfected with CCK-A or CCK-B receptors. CCK significantly increased p44 MAPK and p42 MAPK activities in AR42J cells. Minimal, half-maximal, and maximal responses were observed at 30 and 500 pM and 10 nM, respectively, after CCK-8 stimulation and at 100 pM and 1.5 and 30 nM, respectively, after gastrin stimulation. Glycine-extended gastrin had no effect at 100 nM and a small but significant effect at 1 microM. The CCK-B receptor antagonist L365,260 almost totally blocked MAPK activation in AR42J cells after stimulation with gastrin and glycine-extended gastrin and substantially reduced the activation of both kinases by CCK-8, while the CCK-A receptor antagonist L364,718 was much less effective. The CCK-A-selective agonist A71376, however, was an effective stimulant of MAPK activity. In an alternative approach, stably transfected CHO cells bearing either CCK-A or CCK-B receptors were stimulated with CCK-8. Each receptor induced a time-dependent increase in activity of both MAPKs by five- to sixfold in CCK-A- and CCK-B-bearing cells. In conclusion, both CCK-A and CCK-B receptors activate MAPK in AR42J cells and in transfected CHO cells.

Cholecystokinin and EGF activate a MAPK cascade by different mechanisms in rat pancreatic acinar cells

The effects of activating the Gq protein-coupled cholecystokinin (CCK) receptor on different proteins/signaling molecules in the mitogen-activated protein kinase (MAPK) cascade in pancreatic acinar cells were analyzed and compared with the effects of activating the tyrosine kinase-coupled epidermal growth factor (EGF) receptor. Both EGF and CCK octapeptide rapidly increased the activity of the MAPKs [extracellular signal-regulated kinase (ERK) 1 and ERK2], reaching a maximum within 2.5 min when 3.9- and 8.5-fold increases, respectively, were observed. The EGF-induced increase of MAPK activity was transient, with only a slight elevation after 30 min, whereas CCK-stimulated MAPK remained at a high level of activation to 60 min. The protein kinase C inhibitor GF-109203X abolished the activation by phorbol ester and inhibited the effect of CCK by 78% but had no effect on EGF-activated MAPK activity. EGF and CCK activated both forms of MAPK kinase (MEK), with CCK having a much larger effect, activating MEK1 by 6-fold and MEK2 by 10-fold, whereas EGF activated both MEKs by only 2-fold. Immunoblotting revealed three different forms of Raf in pancreatic acinar cells. Of the total basal Raf kinase activity, 3.7% was Raf-A, 89.0% was Raf-B, and 7.3% was c-Raf-1. All three forms of Raf were stimulated to a greater extent by CCK than by EGF, which was especially evident for Raf-A and c-Raf-1. The effect of CCK in activating Rafs was at least partially mimicked by stimulation with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. EGF significantly increased GTP-bound Ras by 183 and 164% at 2.5 and 10 min, respectively; CCK and TPA had no measurable effect. Our study suggests that CCK and EGF activate the MAPK cascade by distinct mechanisms in pancreatic acinar cells.

CCK-B receptors produce similar signals but have opposite growth effects in CHO and Swiss 3T3 cells

Rat cholecystokinin-B (CCK-B) receptors were transfected into Chinese hamster ovary (CHO)-K1 (CHO-CCK-B) and Swiss 3T3 (Swiss 3T3-CCK-B) cells, and the effects of receptor activation on cell proliferation and intracellular signaling were investigated. CCK octapeptide (CCK-8) treatment had no effect on cell growth in quiescent CHO-CCK-B cells but inhibited DNA synthesis, proliferation, and colony formation when the cells were grown in fetal bovine serum (FBS). In contrast, CCK-8 stimulated DNA synthesis in quiescent Swiss 3T3-CCK-B cells and had no effect when the cells were grown in FBS. These differences in growth responses were not due to differences in the level of receptor expression, as similar numbers of receptors were present in both cell types. To determine whether the different growth effects were due to differences in receptor coupling to common second messenger pathways, we investigated the effects of CCK-8 on several known intracellular signals. In both cell types, CCK-8 stimulated increases in intracellular Ca2+ concentration and polyphosphoinositide hydrolysis with similar potencies and efficacies. CCK-8 also stimulated arachidonate release from both cell types, although the potency was higher in the CHO cells. Adenosine 3',5'-cyclic monophosphate generation was observed at high agonist concentrations in both cell types and was much greater in cells with higher receptor density. In summary, receptor activation had opposite effects on growth parameters in CHO and Swiss 3T3 cells, but only minor differences were observed in the characteristics of CCK-B receptor coupling to specific second messengers in the two cell types. Thus cellular context is a principal determinant of the biological effects of CCK-B receptor activation, and differences in biological responses may occur independently of major differences in receptor coupling.

Regulation of macrophage cytokine production by prostaglandin E2. Distinct roles of cyclooxygenase-1 and -2

Prostaglandin E2 (PGE2) modulates a variety of physiological processes including the production of inflammatory cytokines. There are two cyclooxygenase (Cox) enzymes, Cox-1 and Cox-2, that are responsible for initiating PGE2 synthesis. These isozymes catalyze identical biosynthetic reactions but are regulated by different mechanisms in the cell. This report examines differences in the roles of Cox-1 and Cox-2 in regulating cytokine synthesis in macrophages. We employed agents that selectively modulate the activity of each isozyme and measured their effects on synthesis of interleukin (IL)-6, IL-1, and tumor necrosis factor-alpha by peritoneal macrophages. Among these three cytokines, only IL-6 synthesis was stimulated by production of endogenous PGE2. This effect was specifically linked to activation of Cox-2 and not Cox-1. The specificity derives, partly, from the timing of the production of PGE2 following stimulation of each isozyme and from induction of ancillary signals that control the response to PGE2. The experimental findings demonstrate that the effects of Cox-1 and Cox-2 activity on macrophage IL-6 synthesis are segregated. This provides a mechanism for IL-6 to be induced selectively during inflammation.

Fabrication of multipassband moiré resonators in fibers by the dual-phase-mask exposure method

We report on the fabrication of in-fiber moiré filters by dual exposure of a nondedicated chirped phase mask. This simple technique produces broadband filters whose structure depends only on an intermediate stretch between two identical UV exposures. We demonstrate moiré filters with as many as four narrow passbands within a 2-nm stopband.

Is the outcome of in-vitro fertilization and embryo transfer treatment improved by spontaneous or surgical drainage of a hydrosalpinx?

A pilot study was designed to examine whether the outcome of embryo transfer in women with a hydrosalpinx might be improved by surgical drainage of the hydrosalpinx at the time of oocyte collection for in-vitro fertilization treatment. A comparative, controlled but retrospective analysis of the results was performed of all women with infective tubal damage aged <40 years old, who had ovulatory cycles, a normal uterus and a partner with normal spermatozoa. A standardized treatment regimen was used. A maximum of three embryos were transferred. Hydrosalpinx was defined by prior hysterosalpingography and/or laparoscopy with transcervical dye injection. A total of 237 embryo transfer cycles in women with hydrosalpinges (tubal distension not visible in 151, visible but not drained in 30 and drained in 56) were compared with 705 embryo transfer cycles in women with tubal disease but no hydrosalpinx. Results were analysed in the first three cycles but also separately in the first cycle to check for bias. Success rates were higher in the first cycle, but did not significantly influence overall differences. Implantation rates were significantly reduced overall in the hydrosalpinx group (8.0 versus 13.2% for controls; P < 0.001), being 8.3% (P < 0.01) in the subgroup without evident tubal distension and 7.5% (not significant) in the drained hydrosalpinx group. This study shows that tubal damage with distal occlusion is associated with a marked reduction in embryo implantation, even in the absence of obvious fluid distension. Surgical drainage of distended hydrosalpinges appears to offer no benefit.