Interleukin 10 (IL-10) and viral IL-10 strongly reduce antigen-specific human T cell proliferation by diminishing the antigen-presenting capacity of monocytes via downregulation of class II major histocompatibility complex expression

Interleukin 10 (IL-10) and viral IL-10 (v-IL-10) strongly reduced antigen-specific proliferation of human T cells and CD4+ T cell clones when monocytes were used as antigen-presenting cells. In contrast, IL-10 and v-IL-10 did not affect the proliferative responses to antigens presented by autologous Epstein-Barr virus-lymphoblastoid cell line (EBV-LCL). Inhibition of antigen-specific T cell responses was associated with downregulation of constitutive, as well as interferon gamma- or IL-4-induced, class II MHC expression on monocytes by IL-10 and v-IL-10, resulting in the reduction in antigen-presenting capacity of these cells. In contrast, IL-10 and v-IL-10 had no effect on class II major histocompatibility complex (MHC) expression on EBV-LCL. The reduced antigen-presenting capacity of monocytes correlated with a decreased capacity to mobilize intracellular Ca2+ in the responder T cell clones. The diminished antigen-presenting capacities of monocytes were not due to inhibitory effects of IL-10 and v-IL-10 on antigen processing, since the proliferative T cell responses to antigenic peptides, which did not require processing, were equally well inhibited. Furthermore, the inhibitory effects of IL-10 and v-IL-10 on antigen-specific proliferative T cell responses could not be neutralized by exogenous IL-2 or IL-4. Although IL-10 and v-IL-10 suppressed IL-1 alpha, IL-1 beta, tumor necrosis factor alpha (TNF-alpha), and IL-6 production by monocytes, it was excluded that these cytokines played a role in antigen-specific T cell proliferation, since normal antigen-specific responses were observed in the presence of neutralizing anti-IL-1, -IL-6, and -TNF-alpha mAbs. Furthermore, addition of saturating concentrations of IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha to the cultures had no effect on the reduced proliferative T cell responses in the presence of IL-10, or v-IL-10. Collectively, our data indicate that IL-10 and v-IL-10 can completely prevent antigen-specific T cell proliferation by inhibition of the antigen-presenting capacity of monocytes through downregulation of class II MHC antigens on monocytes.

Standards of Care for the Health of Transgender and Gender Diverse People, Version 8

Background: Transgender healthcare is a rapidly evolving interdisciplinary field. In the last decade, there has been an unprecedented increase in the number and visibility of transgender and gender diverse (TGD) people seeking support and gender-affirming medical treatment in parallel with a significant rise in the scientific literature in this area. The World Professional Association for Transgender Health (WPATH) is an international, multidisciplinary, professional association whose mission is to promote evidence-based care, education, research, public policy, and respect in transgender health. One of the main functions of WPATH is to promote the highest standards of health care for TGD people through the Standards of Care (SOC). The SOC was initially developed in 1979 and the last version (SOC-7) was published in 2012. In view of the increasing scientific evidence, WPATH commissioned a new version of the Standards of Care, the SOC-8. Aim: The overall goal of SOC-8 is to provide health care professionals (HCPs) with clinical guidance to assist TGD people in accessing safe and effective pathways to achieving lasting personal comfort with their gendered selves with the aim of optimizing their overall physical health, psychological well-being, and self-fulfillment. Methods: The SOC-8 is based on the best available science and expert professional consensus in transgender health. International professionals and stakeholders were selected to serve on the SOC-8 committee. Recommendation statements were developed based on data derived from independent systematic literature reviews, where available, background reviews and expert opinions. Grading of recommendations was based on the available evidence supporting interventions, a discussion of risks and harms, as well as the feasibility and acceptability within different contexts and country settings. Results: A total of 18 chapters were developed as part of the SOC-8. They contain recommendations for health care professionals who provide care and treatment for TGD people. Each of the recommendations is followed by explanatory text with relevant references. General areas related to transgender health are covered in the chapters Terminology, Global Applicability, Population Estimates, and Education. The chapters developed for the diverse population of TGD people include Assessment of Adults, Adolescents, Children, Nonbinary, Eunuchs, and Intersex Individuals, and people living in Institutional Environments. Finally, the chapters related to gender-affirming treatment are Hormone Therapy, Surgery and Postoperative Care, Voice and Communication, Primary Care, Reproductive Health, Sexual Health, and Mental Health. Conclusions: The SOC-8 guidelines are intended to be flexible to meet the diverse health care needs of TGD people globally. While adaptable, they offer standards for promoting optimal health care and guidance for the treatment of people experiencing gender incongruence. As in all previous versions of the SOC, the criteria set forth in this document for gender-affirming medical interventions are clinical guidelines; individual health care professionals and programs may modify these in consultation with the TGD person.

Lassa fever. Effective therapy with ribavirin

In a study of Lassa fever in Sierra Leone, West Africa, we identified two variables associated with a high risk of death, and we evaluated the efficacy of ribavirin and Lassa virus-convalescent plasma for the treatment of Lassa fever. A serum aspartate aminotransferase level greater than or equal to 150 IU per liter at the time of hospital admission was associated with a case-fatality rate of 55 percent (33 of 60). Patients with the same risk factor who were treated for 10 days with intravenous ribavirin, begun within the first 6 days after the onset of fever, had a case-fatality rate of 5 percent (1 of 20) (P = 0.0002 by Fisher's exact test). Patients whose treatment began seven or more days after the onset of fever had a case-fatality rate of 26 percent (11 of 43) (P = 0.01). Viremia with levels greater than or equal to 10(3.6) TCID50 per milliliter on admission was associated with a case-fatality rate of 76 percent (35 of 46). Patients with this risk factor who were treated with intravenous ribavirin within the first six days after onset of fever had a case-fatality rate of 9 percent (1 of 11) (P = 0.006), whereas those treated after seven days or more of illness had a fatality rate of 47 percent (9 of 19) (P = 0.035). Oral ribavirin was also effective in patients at high risk of death. Lassa-convalescent plasma did not significantly reduce mortality in any of the high-risk groups. We conclude that ribavirin is effective in the treatment of Lassa fever and that it should be used at any point in the illness, as well as for postexposure prophylaxis.

The child PTSD Symptom Scale: a preliminary examination of its psychometric properties

Reports on the development and preliminary validation of the Child PTSD Symptom Scale (CPSS) for children and adolescents. The CPSS is a new instrument that was developed to assess the severity of Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) posttraumatic stress disorder symptoms in children exposed to trauma. The CPSS was administered to 75 school-age children approximately 2 years after the 1994 Northridge, California, earthquake. The psychometric properties of the CPSS show high internal consistency and test-retest reliability for both the total score and the three subscales. Convergent validity with the Child Post-Traumatic Stress Disorder Reaction Index (CPTSD-RI) was established. As expected, the correlations of the CPSS with depression and anxiety measures were lower than those with the CPTSD-RI, providing some support for discriminant validity of the CPSS. These results suggest that the CPSS is a useful tool for the assessment of posttraumatic stress disorder (PTSD) severity and for the screening of PTSD diagnosis among traumatized children.

Tumor necrosis factor identified in multiple sclerosis brain

Frozen brain specimens from patients with multiple sclerosis (MS) and other neurologic diseases were analyzed using immunocytochemical techniques for the presence of TNF. In brain lesions in MS, and subacute sclerosing panencephalitis, TNF+ cells were demonstrated. At the lesion site in MS, TNF+ staining is associated with both astrocytes and macrophages. These observations were not made in Alzheimer's disease or normal brain tissue. The presence of TNF in MS lesions suggests a significant role for cytokines and the immune response in disease progression.

Isolation of the etiologic agent of Korean Hemorrhagic fever

Lung tissues from 73 rodents (Apodemus agrarius coreae) gave specific immunofluorescent reactions when they reacted with sera from patients convalescing from Korean hemorrhagic fever. Similar staaining was observed in the lungs of A. agrarius inoculated with acute-phase sera obtained from two patients with this disease. The unidentified agent was successfully propagated in adult A. agrarius through eight passages representing a cumulative dilution of greater than 10(-17). Experimentally inoculated rodents developed specific fluorescent antigen in the lung, kidney, liver, parotid glands, and bladder. Organs, especially lungs, were positive beginning 10 days and continuing through 69 days after inoculation. The agent could not be cultivated in several types of cell cultures nor in laboratory animals. No fluorescence was observed when infected A. agrarius lung tissues were reacted with antisera to Marburg virus, Ebola virus, and serval arenaviruses. Diagnostic increases in immunofluorescent antibodies occurred in 113 of 116 severe and 11 of 34 milder cases of clinically suspected Korean hemorrhagic fever. Antibodies were present during the first week of symptoms, reached a peak at the end of the second week, and persisted for up to 14 years. Convalescent-phase sera from four persons suffering a similar disease in the Soviet Union were also positive for antibodies.

Drosophila Mad binds to DNA and directly mediates activation of vestigial by Decapentaplegic

The TGF-beta (transforming growth factor-beta)-related signalling proteins, including Decapentaplegic (Dpp) in Drosophila-and bone morphogenic proteins and activin in vertebrates, affect the growth and patterning of a great variety of structures. However, the mechanisms by which these ligands regulate gene expression are not understood. Activation of complexes of type I with type II receptors results in the phosphorylation and nuclear localization of members of the SMAD protein family, which are thought to act as co-activators of transcription, perhaps in conjunction with sequence-specific cofactors. Here we show that the amino-terminal domain of the Drosophila Mothers against dpp protein (Mad), a mediator of Dpp signalling, possesses a sequence-specific DNA-binding activity that becomes apparent when carboxy-terminal residues are removed. Mad binds to and is required for the activation of an enhancer within the vestigial wing-patterning gene in cells across the entire developing wing blade. Mad also binds to Dpp-response elements in other genes. These results suggest that Dpp signalling regulates gene expression by activating Mad binding to target gene enhancers.

A prospective study of the epidemiology and ecology of Lassa fever

In studies of Lassa fever in Sierra Leone, the prevalence of human antibody to Lassa virus ranged from 8% to 52%. Mastomys natalensis, the reservoir of Lassa virus, constituted 50%-60% of the rodents captured in houses but only 10%-20% of those captured in surrounding agriculture and bush areas (chi 2 = 90.2, P less than 10(-6), df = 1), a finding suggesting that houses are the most-important location for transmission of Lassa virus. Viral infection of Mastomys from houses ranged from 0% to 80%. The incidence of seroconversions in susceptible persons ranged from 5% to 22% per year; the ratio of illness to infection ranged from 9% to 26%, and the proportion of febrile illness associated with seroconversion was 5%-14%. Eightfold rises in titer of antibody occurred in 1%-18% of the antibody-positive population, a result suggesting reinfection. We estimate the ratio of fatalities to infection to be 1%-2%, a rate lower than estimates based on hospitalized cases. The high incidence of Lassa fever makes it a major problem in West Africa.

Head injury and the risk of AD in the MIRAGE study

OBJECTIVES

It has been suggested in some studies that head injury is a risk factor for AD, and that this risk is heightened among carriers of the APOE-epsilon4 allele. We examined the effects of head injury and APOE genotype on AD risk in a large family study.

SUBJECTS

A total of 2,233 probands who met criteria for probable or definite AD and their 14,668 first-degree family members (4,465 parents, 7,694 siblings, and 2,509 spouses) were ascertained at 13 centers in the United States, Canada, and Germany participating in the MIRAGE (Multi-Institutional Research in Alzheimer Genetic Epidemiology) project. Information on head injury was collected by interview of multiple informants and review of medical records. Nondemented relatives and spouses served as control subjects for this study.

METHODS

Odds of AD for head trauma with or without loss of consciousness were computed by comparing probands with unaffected spouses using conditional logistic regression analysis. To account for the unique biologic relationship between probands and their parents and siblings, odds of AD were computed using a generalized estimating equation (GEE) Poisson regression approach. GEE logistic regression was used to examine the joint effects of APOE genotype and head injury on the odds of AD in probands and a control group comprised of unaffected siblings and spouses.

RESULTS

Comparison of probands with their unaffected spouses yielded odds ratios for AD of 9.9 (95% CI, 6.5 to 15.1) for head injury with loss of consciousness and 3.1 (2.3 to 4.0) for head injury without loss of consciousness. The corresponding odds derived from the comparison of probands with their parents and sibs were 4.0 (2.9 to 5.5) for head injury with loss of consciousness and 2.0 (1.5 to 2.7) for head injury without loss of consciousness. Head injury without loss of consciousness did not significantly increase the risk of AD in spouses (OR = 1.3; 95% CI, 0.4 to 4.1). The joint effects of head injury and APOE genotype were evaluated in a subsample of 942 probands and 327 controls (spouses and siblings). Head injury increased the odds of AD to a greater extent among those lacking epsilon4 (OR = 3.3) than among epsilon4 heterozygotes (OR = 1.8) or homozygotes (OR = 1.3).

CONCLUSION

Head injury is a risk factor for AD. The magnitude of the risk is proportional to severity and heightened among first-degree relatives of AD patients. The influence of head injury on the risk of AD appears to be greater among persons lacking APOE-epsilon4 compared with those having one or two epsilon4 alleles, suggesting that these risk factors may have a common biologic underpinning.

The uptake and intracellular fate of PLGA nanoparticles in epithelial cells

Biodegradable polymer nanoparticles (NPs) are a promising approach for intracellular delivery of drugs, proteins, and nucleic acids, but little is known about their intracellular fate, particularly in epithelial cells, which represent a major target. Rhodamine-loaded PLGA (polylactic-co-glycolic acid) NPs were used to explore particle uptake and intracellular fate in three different epithelial cell lines modeling the respiratory airway (HBE), gut (Caco-2), and renal proximal tubule (OK). To track intracellular fate, immunofluorescence techniques and confocal microscopy were used to demonstrate colocalization of NPs with specific organelles: early endosomes, late endosomes, lysosomes, endoplasmic reticulum (ER), and Golgi apparatus. Confocal analysis demonstrated that NPs are capable of entering cells of all three types of epithelium. NPs appear to colocalize with the early endosomes at short times after exposure (approximately 2 h), but are also found in other compartments within the cytoplasm, notably Golgi and, possibly, ER, as time progressed over the period of 4-24 h. The rate and extent of uptake differed among these cell lines: at a fixed particle/cell ratio, cellular uptake was most abundant in OK cells and least abundant in Caco-2 cells. We present a model for the intracellular fate of particles that is consistent with our experimental data.

Operational implementation of prospective genotyping for personalized medicine: the design of the Vanderbilt PREDICT project

The promise of "personalized medicine" guided by an understanding of each individual's genome has been fostered by increasingly powerful and economical methods to acquire clinically relevant information. We describe the operational implementation of prospective genotyping linked to an advanced clinical decision-support system to guide individualized health care in a large academic health center. This approach to personalized medicine entails engagement between patient and health-care provider, identification of relevant genetic variations for implementation, assay reliability, point-of-care decision support, and necessary institutional investments. In one year, approximately 3,000 patients, most of whom were scheduled for cardiac catheterization, were genotyped on a multiplexed platform that included genotyping for CYP2C19 variants that modulate response to the widely used antiplatelet drug clopidogrel. These data are deposited into the electronic medical record (EMR), and point-of-care decision support is deployed when clopidogrel is prescribed for those with variant genotypes. The establishment of programs such as this is a first step toward implementing and evaluating strategies for personalized medicine.

Characterization of degP, a gene required for proteolysis in the cell envelope and essential for growth of Escherichia coli at high temperature

The degP gene, required for proteolysis in the cell envelope of Escherichia coli, maps at approximately 3.5 min on the chromosome. Null mutations in degP result in temperature-sensitive growth. In certain genetic backgrounds, expression of abnormal periplasmic or inner membrane proteins (protein fusions or proteins with internal deletions) enhances the temperature-sensitive phenotype. Such growth defects were used as a selection for cloning the degP gene into Mud4042 and pACYC184 plasmid vectors, and a restriction map was determined. Analysis of deletion and insertion mutations on one of these plasmids showed that the degP gene is approximately 1.5 kilobases in size. The plasmid-encoded DegP protein had an apparent molecular weight of 50,000, as determined by maxicell analysis. Protein fusions between DegP and alkaline phosphatase had high alkaline phosphatase enzymatic activity, indicating that DegP is a periplasmic or membrane protein.

Localization of the malignant hyperthermia susceptibility locus to human chromosome 19q12-13.2

Malignant hyperthermia (MH) is an inherited human skeletal muscle disorder and is one of the main causes of death due to anaesthesia. The reported incidence of MH varies from 1 in 12,000 in children to 1 in 40,000 in adults. MH is triggered in susceptible people by all commonly used inhalational anaesthetics; it is characterized by a profoundly accelerated muscle metabolism, contractures, hyperthermia and tachycardia. Susceptibility to MH (MHS) is predicted by contracture tests on muscle tissue obtained by biopsy. An almost identical disorder known as porcine MH exists in pigs. The genetics of the porcine syndrome have been extensively studied; the locus controlling expression of porcine MH is genetically linked to the glucose phosphate isomerase locus (GPI). In man, GPI has been mapped to the q12-13.2 region of chromosome 19 (refs 10-12). We have now investigated genetic linkage in several extended Irish pedigrees in which MHS is segregating as an autosomal dominant trait. Here we show linkage between MHS and DNA markers from the GPI region of human chromosome 19 with a maximum log likelihood ratio (lod score) of 5.65 at the CYP2A locus. These results indicate that human and porcine MH are most probably due to mutations in homologous genes, and also provide a potentially accurate and noninvasive method of diagnosis for MHS.

Noncompetitive excitatory amino acid receptor antagonists

In the first article in this series, Watkins, Krogsgaard-Larsen and Honoré outlined the structure-activity requirements at the receptor sites for excitatory amino acids in the mammalian CNS. The postsynaptic depolarizing actions of glutamate are thought to be mediated by NMDA, AMPA and kainate receptors. Here David Lodge and Kenneth M. Johnson review some of the recent developments in the pharmacology of other means by which the function of these receptors may be modulated. Divalent cations, phencyclidine-like drugs, glycine analogues and polyamines all modulate NMDA receptors whereas barbiturates and some arthropod toxins reduce channel responses to non-NMDA receptor agonists. Modes of action and implications for physiology and pathophysiology are discussed.

Comparison and reproducibility of visual echocardiographic and quantitative radionuclide left ventricular ejection fractions

Left ventricular (LV) ejection fraction (EF) is commonly assessed by equilibrium radionuclide angiography and echocardiography. These methods are presumed to be interchangeable for this purpose. This study (1) compares quantification of LVEF by equilibrium radionuclide angiography with visual estimation of LVEF by echocardiography, (2) determines the reproducibility of both methods, and (3) evaluates whether differences in determinations of LVEF are of clinical relevance. Seventy-three clinically stable patients had both equilibrium radionuclide angiography and echocardiography performed within a 4-day period. LVEF by both techniques was compared after blinded analysis by 3 echocardiographers and 3 nuclear technologists. Reproducibility was assessed by blinded repeat analysis after a 1-week interval. The frequency of differences in repeat assessments of EF that the authors considered to be of potential clinical relevance (i.e., difference > or = 10% EF units) was assessed for both techniques. Correlation of LVEF determined by both methods was good (r = 0.81, SEE = 3.5) but with substantial differences in individual patients (limits of agreement, 23.6%). Intra- and inter-observer reproducibility was good for both methods, but better for radionuclide LVEF than for echocardiographic LVEF. Limits of agreement were substantially better for radionuclide LVEF than for echocardiographic LVEF (1.8% to 3.6% versus 13.4% to 17.4%, respectively). Clinically relevant differences did not occur on repeat processing of equilibrium radionuclide angiography. In contrast, potentially clinically relevant differences occurred in 8% to 26% of studies on repeat analysis of echocardiography. Thus, LVEF determined by equilibrium radionuclide angiography and echocardiography show good agreement. Both methods provide clinically valuable measurements for LV function. However, when a precisely reproducible measurement is required for patient management decisions, equilibrium radionuclide angiography is the method of choice.

Transcriptomic profiling across the nonalcoholic fatty liver disease spectrum reveals gene signatures for steatohepatitis and fibrosis

The mechanisms that drive nonalcoholic fatty liver disease (NAFLD) remain incompletely understood. This large multicenter study characterized the transcriptional changes that occur in liver tissue across the NAFLD spectrum as disease progresses to cirrhosis to identify potential circulating markers. We performed high-throughput RNA sequencing on a discovery cohort comprising histologically characterized NAFLD samples from 206 patients. Unsupervised clustering stratified NAFLD on the basis of disease activity and fibrosis stage with differences in age, aspartate aminotransferase (AST), type 2 diabetes mellitus, and carriage of PNPLA3 rs738409, a genetic variant associated with NAFLD. Relative to early disease, we consistently identified 25 differentially expressed genes as fibrosing steatohepatitis progressed through stages F2 to F4. This 25-gene signature was independently validated by logistic modeling in a separate replication cohort (n = 175), and an integrative analysis with publicly available single-cell RNA sequencing data elucidated the likely relative contribution of specific intrahepatic cell populations. Translating these findings to the protein level, SomaScan analysis in more than 300 NAFLD serum samples confirmed that circulating concentrations of proteins AKR1B10 and GDF15 were strongly associated with disease activity and fibrosis stage. Supporting the biological plausibility of these data, in vitro functional studies determined that endoplasmic reticulum stress up-regulated expression of AKR1B10, GDF15, and PDGFA, whereas GDF15 supplementation tempered the inflammatory response in macrophages upon lipid loading and lipopolysaccharide stimulation. This study provides insights into the pathophysiology of progressive fibrosing steatohepatitis, and proof of principle that transcriptomic changes represent potentially tractable and clinically relevant markers of disease progression.

A case-control study of the clinical diagnosis and course of Lassa fever

A prospective case-control study of Lassa fever was established in Sierra Leone to measure the frequency and case-fatality ratio of Lassa fever among febrile hospital admissions and to better delineate the clinical diagnosis and course of this disease. Lassa fever was responsible for 10%-16% of all adult medical admissions and for approximately 30% of adult deaths in the two hospitals studied. The case-fatality ratio for 441 hospitalized patients was 16.5%. We found the best predictor of Lassa fever to be the combination of fever, pharyngitis, retrosternal pain, and proteinuria (predictive value together, .81); of outcome, the best predictor was the combination of fever, sore throat, and vomiting (relative risk of death, 5.5). Complications included mucosal bleeding (17%), bilateral or unilateral eighth-nerve deafness (4%), and pleural (3%) or pericardial (2%) effusion. Lassa fever is endemic in this area and is a more-common cause of hospital admission and death than has previously been described; this disease must be considered when diagnosing febrile illness in West Africa.

Cadherin function is required for axon outgrowth in retinal ganglion cells in vivo

The cell-cell adhesion molecule N-cadherin strongly promotes neurite outgrowth in cultured retinal neurons. To test whether cadherins regulate process outgrowth in retinal neurons in vivo, we have blocked cadherin function in single cells by expression of a dominant negative N-cadherin mutant. We report that when cadherin function is inhibited, axon and dendrite outgrowth are severely impaired, particularly in retinal ganglion cells. Laminar migration and cell type specification, by contrast, appear unaffected. Further, expression of the catenin-binding domain of N-cadherin, which blocks cadherin-mediated adhesion in early embryos, does not affect axon outgrowth, suggesting that outgrowth and adhesion are mediated by distinct regions of the cytoplasmic domain. These findings indicate that cadherins play an essential role in the initiation and extension of axons from retinal ganglion cells in vivo.

PC-1 nucleoside triphosphate pyrophosphohydrolase deficiency in idiopathic infantile arterial calcification

Inogranic pyrophosphate (PPi) inhibits hydroxyapatite deposition, and mice deficient in the PPi-generating nucleoside triphosphate pyrophosphohydrolase (NTPPPH) Plasma cell membrane glycoprotein-1 (PC-1) develop peri-articular and arterial calcification in early life. In idiopathic infantile arterial calcification (IIAC), hydroxyapatite deposition and smooth muscle cell (SMC) proliferation occur, sometimes associated with peri-articular calcification. Thus, we assessed PC-1 expression and PPi metabolism in a 25-month-old boy with IIAC and peri-articular calcifications. Plasma PC-1 was <1 ng/ml by enzyme-linked immunosorbent assay in the proband, but 10 to 30 ng/ml in unaffected family members and controls. PC-1 functioned to raise extracellular PPi in cultured aortic SMCs. However, PC-1 was sparse in temporal artery lesion SMCs in the proband, unlike the case for SMCs in atherosclerotic carotid artery lesions of unrelated adults. Proband plasma and explant-cultured dermal fibroblast NTPPPH and PPi were markedly decreased. The proband was heterozygous at the PC-1 locus, and sizes of PC-1 mRNA and polypeptide, and the PC-1 mRNA-coding region sequence were normal in proband fibroblasts. However, immunoreactive PC-1 protein was relatively sparse in proband fibroblasts. In conclusion, deficient extracellular PPi and a deficiency of PC-1 NTPPPH activity can be associated with human infantile arterial and peri-articular calcification, and may help explain the sharing of certain phenotypic features between some IIAC patients and PC-1-deficient mice.

The role of a stress-response protein in Salmonella typhimurium virulence

We recently described the use of selective transposon mutagenesis to generate a series of avirulent mutants of a pathogenic strain of Salmonella typhimurium. Cloning and sequencing of the insertion sites from two of these mutants reveals that both have identical locations within an open reading frame that is highly homologous to a gene, htrA, encoding a heat-shock protein in Escherichia coli. DNA sequence analysis of S. typhimurium htrA reveals the presence of a gene capable of encoding a protein with a calculated Mr of 49316 that has 88.7% protein:protein homology with its E. coli counterpart. In E. coli, lesions in this gene, also known as degP, reduce proteolytic degradation of aberrant periplasmic proteins. Characteristics of the S. typhimurium htrA mutants, 046 and 014, in vivo and in vitro suggested that they are avirulent because of impaired ability to survive and/or replicate in host tissues. In vitro, the S. typhimurium htrA mutants 046 and 014 are not temperature-sensitive but were found to be more susceptible to oxidative stress than the parent, suggesting that they may be less able to withstand oxidative killing within macrophages.

Neurobiology of cocaine abuse

The recent escalation of cocaine abuse has increased awareness of the need to understand the behavioral effects of cocaine and the determinants of those effects. Cocaine alters both conditioned and unconditioned behavior, and has prominent reinforcing and subjective effects that are particularly relevant to its abuse. An increase in CNS dopamine neurotransmission, resulting from a competitive blockade of high-affinity dopamine uptake mediated by both D1 and D2 dopamine receptors, is a primary determinant of the behavioral effects of cocaine. Either tolerance or sensitization may develop with repeated administration of cocaine. Dependence also develops, although the behavioral changes associated with cocaine withdrawal are subtle. Although numerous CNS changes have been associated with repeated administration of cocaine, the neuropharmacological mechanisms that underlie the behavioral changes that occur with repeated administration remain to be firmly established. Bill Woolverton and Ken Johnson stress that continued collaboration between behavioral pharmacologists and neuroscientists is critical for a complete understanding of the effects of cocaine.

Nitric oxide induces neurotransmitter release from hippocampal slices

Hydroxylamine (1-300 microM), a nitric oxide generator, stimulated the release of [3H]norepinephrine ([3H]NE) and [14C]acetylcholine ([14C]ACh) from rat hippocampal slices in a concentration-dependent manner (EC50 approximately 30 microM). A maximally effective concentration of hydroxylamine (300 microM) produced a 24-fold increase in the basal [3H]NE and 3.6-fold increase in the in the basal [14C]ACh efflux. Sodium nitroprusside (SNP), also stimulated the release of [3H]NE, but only at high concentrations (10-30 mM). Calcium-free experimental buffer (1 mM EGTA) abolished the response. Hemoglobin (0.3 microM) inhibited the effect of 100 microM hydroxylamine in a manner which was specific for nitric oxide. In addition, 100 microM hydroxylamine increased the efflux of endogenous GABA and glutamate by 3- and 6-fold, respectively.

Highly constrained backprojection for time-resolved MRI

Recent work in k-t BLAST and undersampled projection angiography has emphasized the value of using training data sets obtained during the acquisition of a series of images. These techniques have used iterative algorithms guided by the training set information to reconstruct time frames sampled at well below the Nyquist limit. We present here a simple non-iterative unfiltered backprojection algorithm that incorporates the idea of a composite image consisting of portions or all of the acquired data to constrain the backprojection process. This significantly reduces streak artifacts and increases the overall SNR, permitting decreased numbers of projections to be used when acquiring each image in the image time series. For undersampled 2D projection imaging applications, such as cine phase contrast (PC) angiography, our results suggest that the angular undersampling factor, relative to Nyquist requirements, can be increased from the present factor of 4 to about 100 while increasing SNR per individual time frame. Results are presented for a contrast-enhanced PR HYPR TRICKS acquisition in a volunteer using an angular undersampling factor of 75 and a TRICKS temporal undersampling factor of 3 for an overall undersampling factor of 225.