Catastrophic outcomes of noncardiac surgery soon after coronary stenting

OBJECTIVES

To assess the clinical course of patients who have undergone coronary stent placement less than six weeks before noncardiac surgery.

BACKGROUND

Surgical and percutaneous transluminal coronary angioplasty revascularization performed before high-risk noncardiac surgery is expected to reduce perioperative cardiac morbidity and mortality. Perioperative and postoperative complications in patients who have undergone coronary stenting before a noncardiac surgery have not been studied.

METHODS

Forty patients who underwent coronary stent placement less than six weeks before noncardiac surgery requiring a general anesthesia were included in the study (1-39 days, average: 13 days). The records were screened for the occurrence of adverse clinical events, including myocardial infarction, stent thrombosis, peri- and postoperative bleeding and death.

RESULTS

In 40 consecutive patients meeting the study criteria, there were seven myocardial infarctions (MIs), 11 major bleeding episodes and eight deaths. All deaths and MIs, as well as 8/11 bleeding episodes, occurred in patients subjected to surgery fewer than 14 days from stenting. Four patients expired after undergoing surgery one day after stenting. Based on electrocardiogram, enzymatic and angiographic evidence, stent thrombosis accounted for most of the fatal events. The time between stenting and surgery appeared to be the main determinant of outcome.

CONCLUSIONS

Postponing elective noncardiac surgery for two to four weeks after coronary stenting should permit completion of the mandatory antiplatelet regimen, thereby reducing the risk of stent thrombosis and bleeding complications.

Drosophila rhomboid-1 defines a family of putative intramembrane serine proteases

The polytopic membrane protein Rhomboid-1 promotes the cleavage of the membrane-anchored TGFalpha-like growth factor Spitz, allowing it to activate the Drosophila EGF receptor. Until now, the mechanism of this key signaling regulator has been obscure, but our analysis suggests that Rhomboid-1 is a novel intramembrane serine protease that directly cleaves Spitz. In accordance with the putative Rhomboid active site being in the membrane bilayer, Spitz is cleaved within its transmembrane domain, and thus is, to our knowledge, the first example of a growth factor activated by regulated intramembrane proteolysis. Rhomboid-1 is conserved throughout evolution from archaea to humans, and our results show that a human Rhomboid promotes Spitz cleavage by a similar mechanism. This growth factor activation mechanism may therefore be widespread.

Functional neuroimaging studies of reading and reading disability (developmental dyslexia)

Converging evidence from a number of neuroimaging studies, including our own, suggest that fluent word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo-parietal) circuit and a ventral (occipito-temporal) circuit. This posterior system is functionally disrupted in developmental dyslexia. Reading disabled readers, relative to nonimpaired readers, demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers the dorsal circuit predominates at first, and is associated with analytic processing necessary for learning to integrate orthographic features with phonological and lexical-semantic features of printed words. The ventral circuit constitutes a fast, late-developing, word identification system which underlies fluent word recognition in skilled readers.

Mutations in a gene encoding a novel protein tyrosine phosphatase cause progressive myoclonus epilepsy

Lafora's disease (LD; OMIM 254780) is an autosomal recessive form of progressive myoclonus epilepsy characterized by seizures and cumulative neurological deterioration. Onset occurs during late childhood and usually results in death within ten years of the first symptoms. With few exceptions, patients follow a homogeneous clinical course despite the existence of genetic heterogeneity. Biopsy of various tissues, including brain, revealed characteristic polyglucosan inclusions called Lafora bodies, which suggested LD might be a generalized storage disease. Using a positional cloning approach, we have identified at chromosome 6q24 a novel gene, EPM2A, that encodes a protein with consensus amino acid sequence indicative of a protein tyrosine phosphatase (PTP). mRNA transcripts representing alternatively spliced forms of EPM2A were found in every tissue examined, including brain. Six distinct DNA sequence variations in EPM2A in nine families, and one homozygous microdeletion in another family, have been found to cosegregate with LD. These mutations are predicted to cause deleterious effects in the putative protein product, named laforin, resulting in LD.

Neurobiological studies of reading and reading disability

Evidence from neuroimaging studies, including our own, suggest that skilled word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo-parietal) circuit and a ventral (occipito-temporal) circuit. This posterior system appears to be functionally disrupted in developmental dyslexia. Relative to nonimpaired readers, reading-disabled individuals demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers, the dorsal circuit predominates at first, and in conjunction with premotor systems, is associated with analytic processing necessary for learning to integrate orthographic with phonological and lexical semantic features of printed words. The ventral circuit constitutes a fast, late-developing, word form system, which underlies fluency in word recognition.

LEARNING OUTCOMES

As a result of this activity, (1) the participant will learn about a model of lexical processing involving specific cortical regions. (2) The participant will learn about evidence which supports the theory that two dorsal LH systems may be disrupted in developmental dyslexia. (3) The participant will learn that individuals with reading impairment may rely on other regions of the brain to compensate for the disruption of posterior function.

The gene mutated in adult-onset type II citrullinaemia encodes a putative mitochondrial carrier protein

Citrullinaemia (CTLN) is an autosomal recessive disease caused by deficiency of argininosuccinate synthetase (ASS). Adult-onset type II citrullinaemia (CTLN2) is characterized by a liver-specific ASS deficiency with no abnormalities in hepatic ASS mRNA or the gene ASS (refs 1-17). CTLN2 patients (1/100,000 in Japan) suffer from a disturbance of consciousness and coma, and most die with cerebral edema within a few years of onset. CTLN2 differs from classical citrullinaemia (CTLN1, OMIM 215700) in that CTLN1 is neonatal or infantile in onset, with ASS enzyme defects (in all tissues) arising due to mutations in ASS on chromosome 9q34 (refs 18-21). We collected 118 CTLN2 families, and localized the CTLN2 locus to chromosome 7q21.3 by homozygosity mapping analysis of individuals from 18 consanguineous unions. Using positional cloning we identified a novel gene, SLC25A13, and found five different DNA sequence alterations that account for mutations in all consanguineous patients examined. SLC25A13 encodes a 3.4-kb transcript expressed most abundantly in liver. The protein encoded by SLC25A13, named citrin, is bipartite in structure, containing a mitochondrial carrier motif and four EF-hand domains, suggesting it is a calcium-dependent mitochondrial solute transporter with a role in urea cycle function.

Regulated intracellular ligand transport and proteolysis control EGF signal activation in Drosophila

The membrane proteins Star and Rhomboid-1 have been genetically defined as the primary regulators of EGF receptor activation in Drosophila, but their molecular mechanisms have been elusive. Both Star and Rhomboid-1 have been assumed to work at the cell surface to control ligand activation. Here, we demonstrate that they control receptor signaling by regulating intracellular trafficking and proteolysis of the ligand Spitz. Star is present throughout the secretory pathway and is required to export Spitz from the endoplasmic reticulum to the Golgi apparatus. Rhomboid-1 is localized in the Golgi, where it promotes the cleavage of Spitz. This defines a novel growth factor release mechanism that is distinct from metalloprotease-dependent shedding from the cell surface.

Risk of recurrent seizures after two unprovoked seizures

BACKGROUND

Patients with a single unprovoked seizure have about a 35 percent risk of recurrence in the subsequent five years. We studied the risk of recurrence after two unprovoked seizures.

METHODS

We prospectively followed 204 patients with a first unprovoked seizure from the day of the initial seizure. Information was obtained from patients (and verified by a review of their medical records) about the dates and circumstances of any subsequent seizures. The risk of a second, third, and fourth seizure was estimated by the Kaplan-Meier method.

RESULTS

Of the 204 patients, 63 had a second seizure, 41 a third seizure, and 26 a fourth seizure. The mean age of the patients was 36 years, 10 percent were less than 16 years of age, 70 percent were male, 71 percent had epilepsy of unknown cause, and 66 percent had generalized seizures. The risk of a second unprovoked seizure was 33 percent. Among those with a second seizure, the risk of a third unprovoked seizure was 73 percent; among those with a third unprovoked seizure, the risk of a fourth was 76 percent. Most recurrences occurred within one year of the second or third seizure. The risk of a third seizure was higher in those with a presumed cause of epilepsy (relative risk, 1.9; 95 percent confidence interval, 1.0 to 3.4).

CONCLUSIONS

Although only about one third of patients with a first unprovoked seizure will have further seizures within five years, about three quarters of those with two or three unprovoked seizures have further seizures within four years.

Adenocarcinoma of the stomach: review of 1,497 cases

The records of 1,497 patients with histologically proven adenocarcinoma of the stomach were reviewed from Charity Hospital over the 25-year period, 1948 to 1973. The operability rate was 82% and the resectability rate was 48%. In this series gastric carcinoma predominated in males and Negroes. Necropsy studies indicate a similar frequency of involvement of various organs in patients not operated upon as well as those subjected to a prior operation, which suggests the need for some therapeutic endeavors aimed at a wider base than the primary organ. The five-year survival rate, 7.4 overall, varied from 2.0% after esophagogastrectomy to 22.1% after radical subtotal gastrectomy, and to 30.3% for those with localized disease. One hundred one patients survived five years or more, and 5.4% survived ten years or more after the diagnosis of gastric cancer. Radical subtotal gastrectomy gave the best results in this series, whether measured in terms of median survival, five-year survival, or operative mortality. Esophagogastrectomy and by-pass procedures had high mortality and low survival rates, and should be reserved for special conditions.

Incidence of acute symptomatic seizures in Rochester, Minnesota, 1935-1984

We determined the incidence of seizures due to acute CNS insults for residents of Rochester, Minnesota, U.S.A., from 1935 through 1984. The age-adjusted incidence rates for 1955-1984, the period of most complete case ascertainment, was 39.0/100,000 person-years (United States 1970 population as standard). The age-adjusted incidence was considerably higher in men: 52.0 as compared with 29.5 in women. The 3.6% risk of experiencing an acute symptomatic seizure in an 80-year lifespan approaches that of developing epilepsy. The major causes of acute symptomatic seizures were traumatic brain injury, cerebrovascular disease, drug withdrawal, and CNS infections. Each type of acute symptomatic seizure has age, gender, and time period patterns that reflect the occurrence of the underlying cause.

Molecular characterization of a common fragile site (FRA7H) on human chromosome 7 by the cloning of a simian virus 40 integration site

Common fragile sites are chromosomal loci prone to breakage and rearrangement, hypothesized to provide targets for foreign DNA integration. We cloned a simian virus 40 integration site and showed by fluorescent in situ hybridization analysis that the integration event had occurred within a common aphidicolin-induced fragile site on human chromosome 7, FRA7H. A region of 161 kb spanning FRA7H was defined and sequenced. Several regions with a potential unusual DNA structure, including high-flexibility, low-stability, and non-B-DNA-forming sequences were identified in this region. We performed a similar analysis on the published FRA3B sequence and the putative partial FRA7G, which also revealed an impressive cluster of regions with high flexibility and low stability. Thus, these unusual DNA characteristics are possibly intrinsic properties of common fragile sites that may affect their replication and condensation as well as organization, and may lead to fragility.

Integration of T cell receptor-dependent signaling pathways by adapter proteins

The initiation of biochemical signal transduction following ligation of surface receptors with intrinsic cytoplasmic tyrosine kinase activity is common for many cell types. T lymphocytes also require activation of tyrosine kinases following T cell receptor (TCR) ligation for maximal stimulation. However, the TCR has no intrinsic tyrosine kinase activity. Instead, the TCR must rely on cytoplasmic tyrosine kinases that localize to the TCR complex and initiate TCR-mediated signaling events. Although much has been learned regarding how these cytosolic tyrosine kinases are activated and recruited to the TCR complex, relatively little is understood about how these initial events are translated into transcriptional activation of genes that regulate cytokine production, cell proliferation, and cell death. Recently, it has become clear that the class of intracellular molecules known collectively as adapter proteins, molecules with modular domains capable of recruiting additional proteins but that exhibit no intrinsic enzymatic activity, serve to couple proximal biochemical events initiated by TCR ligation with more distal signaling pathways.

LAT is required for tyrosine phosphorylation of phospholipase cgamma2 and platelet activation by the collagen receptor GPVI

In the present study, we have addressed the role of the linker for activation of T cells (LAT) in the regulation of phospholipase Cgamma2 (PLCgamma2) by the platelet collagen receptor glycoprotein VI (GPVI). LAT is tyrosine phosphorylated in human platelets heavily in response to collagen, collagen-related peptide (CRP), and FcgammaRIIA cross-linking but only weakly in response to the G-protein-receptor-coupled agonist thrombin. LAT tyrosine phosphorylation is abolished in CRP-stimulated Syk-deficient mouse platelets, whereas it is not altered in SLP-76-deficient mice or Btk-deficient X-linked agammaglobulinemia (XLA) human platelets. Using mice engineered to lack the adapter LAT, we showed that tyrosine phosphorylation of Syk and Btk in response to CRP was maintained in LAT-deficient platelets whereas phosphorylation of SLP-76 was slightly impaired. In contrast, tyrosine phosphorylation of PLCgamma2 was substantially reduced in LAT-deficient platelets but was not completely inhibited. The reduction in phosphorylation of PLCgamma2 was associated with marked inhibition of formation of phosphatidic acid, a metabolite of 1,2-diacylglycerol, phosphorylation of pleckstrin, a substrate of protein kinase C, and expression of P-selectin in response to CRP, whereas these parameters were not altered in response to thrombin. Activation of the fibrinogen receptor integrin alpha(IIb)beta(3) in response to CRP was also reduced in LAT-deficient platelets but was not completely inhibited. These results demonstrate that LAT tyrosine phosphorylation occurs downstream of Syk and is independent of the adapter SLP-76, and they establish a major role for LAT in the phosphorylation and activation of PLCgamma2, leading to downstream responses such as alpha-granule secretion and activation of integrin alpha(IIb)beta(3). The results further demonstrate that the major pathway of tyrosine phosphorylation of SLP-76 is independent of LAT and that there is a minor, LAT-independent pathway of tyrosine phosphorylation of PLCgamma2. We propose a model in which LAT and SLP-76 are required for PLCgamma2 phosphorylation but are regulated through independent pathways downstream of Syk.

Fetal hemorrhage and platelet dysfunction in SLP-76-deficient mice

The adapter protein SLP-76 is expressed in T lymphocytes and hematopoietic cells of the myeloid lineage, and is known to be a substrate of the protein tyrosine kinases that are activated after ligation of the T-cell antigen receptor. Transient overexpression of SLP-76 in a T-cell line potentiates transcriptional activation after T-cell receptor ligation, while loss of SLP-76 expression abrogates several T-cell receptor-dependent signaling pathways. Mutant mice that lack SLP-76 manifest a severe block at an early stage of thymocyte development, implicating SLP-76 in signaling events that promote thymocyte maturation. While it is clear that SLP-76 plays a key role in development and activation of T lymphocytes, relatively little is understood regarding its role in transducing signals initiated after receptor ligation in other hematopoietic cell types. In this report, we describe fetal hemorrhage and perinatal mortality in SLP-76-deficient mice. Although megakaryocyte and platelet development proceeds normally in the absence of SLP-76, collagen-induced platelet aggregation and granule release is markedly impaired. Furthermore, treatment of SLP-76-deficient platelets with collagen fails to elicit tyrosine phosphorylation of phospholipase C-gamma2 (PLC-gamma2), suggesting that SLP-76 functions upstream of PLC-gamma2 activation. These data provide one potential mechanism for the fetal hemorrhage observed in SLP-76-deficient mice and reveal that SLP-76 expression is required for optimal receptor-mediated signal transduction in platelets as well as T lymphocytes.

Interaction of the von Willebrand factor (vWF) with collagen. Localization of the primary collagen-binding site by analysis of recombinant vWF a domain polypeptides

The von Willebrand factor (vWF) mediates platelet adhesion to the vascular subendothelium by binding to collagen, other matrix constituents, and the platelet receptor glycoproteins Ib/IX and IIb/IIIa. Although substantial progress has been made in defining vWF structure-function relationships, there are conflicting data regarding the location of its collagen-binding site(s). Possible collagen-binding sites have been localized in the A1 and A3 domains of vWF. To study the proposed binding sites, we have expressed cDNA sequences encoding the A1 and A3 domains of vWF in Escherichia coli and purified the resulting proteins from bacterial inclusion bodies. In addition, a chimeric molecule containing residues 465-598 of the vWF A1 domain polypeptide (vWF-A1) fused in frame to residues 1018-1114 of the vWF A3 domain polypeptide (vWF-A3) was also expressed. Each of the three recombinant proteins purified as a monomer and contained a single disulfide bond. As previously reported (Cruz, M. A., Handin, R. I., and Wise, R. J. (1993) J. Biol. Chem. 268, 21238-21245), recombinant vWF-A1 inhibited ristocetin-induced platelet agglutination, but did not compete with vWF multimers for collagen binding. In contrast, vWF-A3 inhibited the binding of multimeric vWF to immobilized collagen, but did not inhibit ristocetin-induced platelet agglutination. Metabolically labeled vWF-A3 bound to immobilized collagen in a saturable and reversible manner with a Kd of 1.8 x 10(-6) M. The vWF-A1/A3 chimera was bifunctional. It inhibited vWF binding to platelet glycoprotein Ib/IX with an IC50 of 0.6 x 10(-6) M and inhibited vWF binding to collagen with an IC50 of 0.5-1.0 x 10(-6) M. These results, taken together, provide firm evidence that the major collagen-binding site in vWF resides in the A3 domain.

Gastrointestinal autonomic nerve tumor: immunohistochemical and molecular identity with gastrointestinal stromal tumor

Gastrointestinal autonomic nerve tumor (GANT) is a gastrointestinal neoplasm that ultrastructurally recapitulates the enteric neural plexus. This study identifies and defines the features of 10 cases of this rare mesenchymal tumor and compares its clinicopathologic and molecular genetic features with the data on gastrointestinal stromal tumor (GIST). The majority of patients in this series presented at an older age (mean 64 years). Tumors arose from the stomach (6), small intestine (2), and retroperitoneum (2). Mean tumor size was 14 cm; however, four neoplasms were <6 cm. Histologically, tumors were spindled or epithelioid; one epithelioid tumor demonstrated a previously undescribed rhabdoid histologic phenotype. All tumors were positive for CD117 (KIT), while eight of 10 were positive for CD34. In contrast, only two were positive for S-100, and all were negative for actin and desmin. Five GANTs demonstrated GIST-specific gain-of-function mutations in the juxtamembrane domain of the c-kit gene (50%). Three of 10 patients died of disease in 22-30 months, one patient died in the postoperative period, and one patient died of complications of CML. The clinicopathologic, histologic, immunohistologic, and molecular features of GANT are similar to GIST, indicating that GANT merely represents a phenotypic variant of GIST.

Prognosis of amyotrophic lateral sclerosis and the effect of referral selection

We followed two cohorts of Amyotrophic Lateral Sclerosis (ALS) patients to examine the survival and prognostic factors of ALS and the impact of selective referral on prognosis of ALS. The first cohort consisted of population-based incident ALS cases from Harris County, Texas, first diagnosed between 1985 and 1988. The second was a clinical series from a tertiary care center in Houston, Texas, diagnosed between 1977 and 1989. The overall 3-year survival was 29% in the incidence cohort and 32% in the referral cohort; however, the 5-year survival was much lower for the incidence cohort than the referral cohort (4% vs 21%). The large difference in 5-year survival was not explained by the distributions of prognostic factors in the two cohorts but due to stronger unfavorable effects of prognostic factors in the incidence cohort than the referral cohort. In both cohorts, older age at diagnosis, bulbar onset, and positive family history of ALS were unfavorable prognostic factors while blacks had better survival than whites or hispanics. We confirmed that longer duration from onset to diagnosis was a favorable prognostic factor in both cohorts but the effect was more pronounced in the referral series.

Effect of Fiber-Polymer Interactions on Fracture Toughness Behavior of Carbon Fiber-Reinforced Epoxy Matrix Composites

The effect of anodic oxidation on high-strength polyacrylonitrile-based carbon fibers has been studied in terms of fiber surface energetics and fracture toughness of the composites. According to contact angle measurements based on the wicking rate of a test liquid, anodic oxidation leads to an increase in surface free energy, mainly due to the increase of its specific (or polar) component. For the carbon-fiber-reinforced epoxy resin matrix system, a direct linear relationship is shown between the specific component and the critical stress intensity factor measured by the single edge notched beam fracture toughness test. From a surface-energetic point of view, the anodic treatment may be suitable for carbon fibers incorporated in a polar organic matrix, resulting in an increased specific component of the surface free energy. Good wetting plays an important role in improving the degree of adhesion at interfaces between fibers and matrices of the resulting composites. Copyright 2000 Academic Press.

Phase II study of capecitabine plus cisplatin as first-line chemotherapy in advanced biliary cancer

BACKGROUND

A phase II study was conducted to assess the efficacy and tolerability of substituting capecitabine for 5-fluorouracil in combination with cisplatin in patients with advanced biliary cancer.

PATIENTS AND METHODS

Patients with previously untreated metastatic or unresectable measurable biliary adenocarcinoma received oral capecitabine 1250 mg/m(2) twice daily on days 1-14, and intravenous cisplatin 60 mg/m(2) on day 1. This cycle was repeated every 21 days.

RESULTS

Forty-two patients were enrolled in this study. Of these, 38 were assessable for efficacy and 41 were assessable for safety. A median of three cycles of treatment (range one to eight) were administered. One patient achieved a complete response, and eight had partial responses, giving an overall response rate of 21.4% in the intention-to-treat population (95% confidence interval 9.1% to 33.9%). The median response duration was 5.1 months. The median time to progression and median overall survival were 3.7 and 9.1 months, respectively. The most common grade 3/4 adverse events were neutropenia (20% of patients), vomiting (12%), diarrhea (7%) and stomatitis (5%). There were no treatment-related deaths.

CONCLUSIONS

The combination of capecitabine and cisplatin has promising antitumor activity and is well tolerated in patients with advanced biliary cancer.

How does the striate cortex begin the reconstruction of the visual world?

The striate cortex transforms the topographic representation of visual space in the lateral geniculate body into a Fourier transform or frequency representation at the complex cell level via the intermediary simple cell stage of "strip integration." Each of these three stages contains essentially the same amount of information, which expresses a conservation of information principle; however, the form of the information is changed. In the transform domain, invariant descriptions of visual objects can be derived to serve as the basic sets required for pattern recognition and memory. We believe that our experimental and theoretical findings are fundamental for understanding the functional organization of the striate cortex.

Commensal Gut Bacteria Convert the Immunosuppressant Tacrolimus to Less Potent Metabolites

Tacrolimus exhibits low and variable drug exposure after oral dosing, but the contributing factors remain unclear. Based on our recent report showing a positive correlation between fecal abundance of Faecalibacterium prausnitzii and oral tacrolimus dose in kidney transplant patients, we tested whether F. prausnitzii and other gut abundant bacteria are capable of metabolizing tacrolimus. Incubation of F. prausnitzii with tacrolimus led to production of two compounds (the major one named M1), which was not observed upon tacrolimus incubation with hepatic microsomes. Isolation, purification, and structure elucidation using mass spectrometry and nuclear magnetic resonance spectroscopy indicated that M1 is a C-9 keto-reduction product of tacrolimus. Pharmacological activity testing using human peripheral blood mononuclear cells demonstrated that M1 is 15-fold less potent than tacrolimus as an immunosuppressant. Screening of 22 gut bacteria species revealed that most Clostridiales bacteria are extensive tacrolimus metabolizers. Tacrolimus conversion to M1 was verified in fresh stool samples from two healthy adults. M1 was also detected in the stool samples from kidney transplant recipients who had been taking tacrolimus orally. Together, this study presents gut bacteria metabolism as a previously unrecognized elimination route of tacrolimus, potentially contributing to the low and variable tacrolimus exposure after oral dosing.

Tyrosine phosphorylation of SLP-76 is downstream of Syk following stimulation of the collagen receptor in platelets

Collagen-related peptide (CRP), a collagen homologue, induces platelet activation through a tyrosine kinase-dependent pathway, leading to sequential tyrosine phosphorylation of Fc receptor (FcR) gamma-chain, Syk, and phospholipase C-gamma2. Here we report that CRP and the platelet low affinity immune receptor FcgammaRIIA stimulate tyrosine phosphorylation of the T cell adapter SLP-76, whereas the G protein-coupled receptor agonist thrombin induces only minor tyrosine phosphorylation. This suggests that SLP-76 has a specific role downstream of receptors that signal via an immunoreceptor tyrosine-based activation motif. Immunoprecipitation studies demonstrate association of SLP-76 with SLAP-130, Vav, Fyn, Lyn, and the FcR gamma-chain in CRP-stimulated platelets. Several of these proteins, including SLP-76, undergo tyrosine phosphorylation in in vitro kinase assays performed on SLP-76 immunoprecipitates. Tyrosine phosphorylation of all of these proteins in the in vitro kinase assay was abrogated by the Src family kinase inhibitor PP1, suggesting that it is mediated by either Fyn or Lyn. The physiological significance of this is uncertain, however, since tyrosine phosphorylation of SLP-76 in vivo is not altered in either Fyn- or Lyn-deficient platelets. CRP stimulation of Syk-deficient platelets demonstrated that in vivo tyrosine phosphorylation of SLP-76 is downstream of Syk. The absence of Syk in the SLP-76 immunoprecipitates raises the possibility that another protein is responsible for bringing SLP-76 to Syk. Candidates for this include those proteins that co-immunoprecipitate with SLP-76, including the FcR gamma-chain. Tyrosine phosphorylation of PLC-gamma2 and Ca2+ mobilization is markedly attenuated in SLP-76-deficient platelets following CRP stimulation, suggesting that the adapter plays a critical role in the regulation of the phospholipase. The increase in tyrosine phosphorylation of SLAP-130 in response to CRP is also inhibited in SLP-76-deficient platelets, placing it downstream of SLP-76. This work identifies SLP-76 as an important adapter molecule that is regulated by Syk and lies upstream of SLAP-130 and PLC-gamma2 in CRP-stimulated platelets.

Incidence and prevalence of amyotrophic lateral sclerosis in Harris County, Texas, 1985-1988

The incidence of amyotrophic lateral sclerosis was determined in Harris County, Texas, for the period 1985 through 1988. Amyotrophic lateral sclerosis cases were ascertained from four sources: area neurologists, hospitals, death certificates, and the Muscular Dystrophy Association. The age-adjusted incidences of 1.27 per 100,000 person-years in males and 1.03 per 100,000 person-years in females were lower than recent rates in the northern US, Canadian, and northern European studies but higher than rates in southern European studies. Comparisons with other recent incidence studies show less uniformity in occurrence of amyotrophic lateral sclerosis, in both the overall rates and in the age- and sex-specific patterns, than was suggested by mortality studies. The incidence of amyotrophic lateral sclerosis among blacks and whites was similar. Hispanic males had incidences similar to white males, although a deficit of female Hispanic cases was found in Harris County. The prevalence of amyotrophic lateral sclerosis peaked in the 65- to 74-year age group at 33 per 100,000 population among males and 19 per 100,000 population for females.

Rice 1Cys-peroxiredoxin over-expressed in transgenic tobacco does not maintain dormancy but enhances antioxidant activity

Possible functions that have been proposed for the plant 1Cys-peroxiredoxin, include activity as a dormancy regulator and as an antioxidant. The transcript level of rice 1Cys-peroxiredoxin (R1C-Prx) rapidly decreased after imbibition of rice seeds, but the protein was detected for 15 days after imbibition. To investigate the function of this protein, we generated transgenic tobacco plants constitutively expressing the R1C-Prx gene. The transgenic R1C-Prx plants showed a germination frequency similar to control plants. However, the transgenic lines exhibited higher resistance against oxidative stress, suggesting that antioxidant activity may be its primary function.

Modification of morphine analgesia by drugs affecting adrenergic and tryptaminergic mechanisms

The effects of drugs that modify adrenergic or tryptaminergic mechanisms were tested on the analgesic action of morphine in mice. Analgesia was assessed by the hot plate method and phenylquinonewrithing method. Reserpine antagonized the analgesic action of morphine in both tests, the maximal effects occurring 6–8 h after the administration of reserpine. p-Chlorophenylalanine antagonized the analgesic action of morphine as assessed by the writhing method but not by the hot plate method. The analgesic action of morphine was not modified in either test by pretreatment with α-methyl-p-tyrosine, propranolol, phentolamine or methysergide. These results suggest that the analgesic action of morphine, as measured in the writhing test, may be mediated by 5-hydroxytryptamine but that other mechanisms may be involved in the hot plate test.