[Sarcoidosis : Dermatological view of a rare multisystem disease]

Sarcoidosis is a rare multisystem inflammatory disease of largely unknown etiology. While pulmonary sarcoidosis is the most abundant organ manifestation, involvement of the skin that occurs in up to 30% of patients is the most common extrapulmonary presentation of the disease. Dermatologists therefore play an important role not only for establishing the diagnosis and delineating it from potential differential diagnoses but also for the interdisciplinary care of the patient. The clinical presentation of skin sarcoidosis is manifold, which occasionally aggravates making the final diagnosis. Specific skin lesions (with granulomas) and nonspecific skin manifestations (without granulomas) can be differentiated. Since a variety of organ systems can be affected, multidisciplinary cooperation is mandatory. Therapy of sarcoidosis is difficult; evidence-based studies and therapy guidelines are widely lacking. Our review intends to outline the characteristic clinical presentations of cutaneous sarcoidosis, describe the diagnostic approach and how to assure or exclude extracutaneous manifestations of sarcoidosis, and suggest a therapy algorithm for the treatment of skin sarcoidosis.

An Examination of Semantic Impairment in Amnestic MCI and AD: What Can We Learn From Verbal Fluency?

Introduction

The Verbal Fluency Test (VF) is commonly used in neuropsychology. Some studies have demonstrated a marked impairment of semantic VF compared to phonemic VF in Alzheimer’s disease (AD). Since amnestic Mild Cognitive Impairment (aMCI) is associated with increased risk of conversion to incident AD, it is relevant to examine whether a similar impairment is observed in this population. The objective of the present empirical study is to compare VF performance of aMCI patients to those of AD and elderly controls matched one-to-one for age and education.

Method

Ninety-six participants divided into three equal groups (N = 32: AD, aMCI and Controls) were included in this study. Participants in each group were, on average, 76 years of age and had 13 years of education. A repeated measures ANOVA with the Group (AD, aMCI, NC) as between-subject factor and the Fluency condition (“P” and “animals”) as within-subject factor was performed. T-tests and simple ANOVAs were also conducted to examine the interaction.

Results

There was a significant interaction between the groups and the verbal fluency condition. In AD, significantly fewer words were produced in both conditions. In contrast, participants with aMCI demonstrated a pattern similar to controls in the phonemic condition, but generated significantly fewer words in the semantic condition.

Conclusion

These results indicate a semantic memory impairment in aMCI revealed by a simple, commonly-used neuropsychological test. Future studies are needed to investigate if semantic fluency deficits can help predict future conversion to AD.

Die Sarkoidose aus dermatologischer Perspektive

Die Sarkoidose ist eine seltene Multisystemerkrankung, welche durch nicht-verkäsende Granulome charakterisiert ist, die sich an verschiedenen Organen manifestieren können. Die Pathogenese der Sarkoidose ist nicht vollständig geklärt, neben genetischen Faktoren spielen auch infektiöse Triggerfaktoren sowie Umwelteinflüsse eine Rolle. Die Lunge ist bei über 90 % der Patienten betroffen und damit das am häufigsten involvierte Organ. Es folgt die Haut, die bei bis zu einem Drittel der Sarkoidose-Patienten Auffälligkeiten aufweist, welche anderen Organbeteiligungen häufig vorausgehen. Es ist daher wichtig, die Sarkoidose der Haut frühzeitig zu diagnostizieren, damit eine symptomorientierte Durchuntersuchung und Therapie in die Wege geleitet werden können. Letztere gestaltet sich oft schwierig, da evidenzbasierte Therapieempfehlungen weitgehend fehlen.

In dieser Übersichtarbeit werden die dermatologische Vielgestaltigkeit der Erkrankung, die empfohlenen fachspezifischen und fachübergreifenden Untersuchungen sowie die Therapiemöglichkeiten vorgestellt und diskutiert.

Prospective study in bullous pemphigoid: association of high serum anti-BP180 IgG levels with increased mortality and reduced Karnofsky score

BACKGROUND

Bullous pemphigoid (BP) is a subepidermal blistering disease characterized by autoantibodies against the two hemidesmosomal proteins, BP180 (type XVII collagen) and BP230. The multicentre prospective BLISTER (Bullous Pemphigoid Steroids and Tetracyclines) trial randomized 253 patients with BP to compare the benefits and harms between initial treatment with doxycycline or prednisolone.

OBJECTIVES

To analyse distinct autoantibody profiles for the prediction of the disease course in a well-characterized cohort of BP sera.

METHODS

One hundred and forty-three patients of the BLISTER trial consented to participate in this serological study. Sera taken at baseline were analysed by (i) indirect immunofluorescence, (ii) anti-BP180 NC16A (16th noncollagenous domain) and anti-BP230 enzyme-linked immunosorbent assay and (iii) immunoblotting with various substrates. Results were then linked with clinical parameters including age, Karnofsky score, number of blisters, related adverse events and mortality.

RESULTS

Disease activity correlated with immunoglobulin (Ig)G anti-BP180 levels but not with levels of anti-BP230 IgG and anti-BP180 IgE. High levels of both anti-BP180 IgG and anti-BP230 IgG were associated with a low Karnofsky score. The presence of anti-BP230 IgG was more frequent in older patients. Those with higher total IgE serum levels suffered from fewer adverse events. Higher IgG anti-BP180 levels were associated with an increased 1-year mortality rate.

CONCLUSIONS

Analysis of the autoantibody profile is not only of diagnostic relevance but may also be helpful in predicting the course of the disease.

Clinical and genetic heterogeneity in familial steroid-sensitive nephrotic syndrome

BACKGROUND

Familial steroid-sensitive nephrotic syndrome (SSNS) is a rare condition. The disease pathophysiology remains elusive. However, bi-allelic mutations in the EMP2 gene were identified, and specific variations in HLA-DQA1 were linked to a high risk of developing the disease.

METHODS

Clinical data were analyzed in 59 SSNS families. EMP2 gene was sequenced in families with a potential autosomal recessive (AR) inheritance. Exome sequencing was performed in a subset of 13 families with potential AR inheritance. Two variations in HLA-DQA1 were genotyped in the whole cohort.

RESULTS

Transmission was compatible with an AR (n = 33) or autosomal dominant (AD, n = 26) inheritance, assuming that familial SSNS is a monogenic trait. Clinical features did not differ between AR and AD groups. All patients, including primary (n = 7) and secondary steroid resistant nephrotic syndrone (SRNS), (n = 13) were sensitive to additional immunosuppressive therapy. Both HLA-DQA1 variations were found to be highly linked to the disease (OR = 4.34 and OR = 4.89; p < 0.001). Exome sequencing did not reveal any pathogenic mutation, neither did EMP2 sequencing.

CONCLUSIONS

Taken together, these results highlight the clinical and genetic heterogeneity in familial SSNS. Clinical findings sustain an immune origin in all patients, whatever the initial steroid-sensitivity. The absence of a variant shared by two families and the HLA-DQA1 variation enrichments suggest a complex mode of inheritance.

Effect of transmembrane pressure control on energy efficiency during skim milk concentration by ultrafiltration at 10 and 50°C

The efficiency of the ultrafiltration process during skim milk concentration was studied using both dynamic and constant (465 or 672kPa) transmembrane pressure experiments at refrigerated temperature (10°C) and high temperature (50°C). The pilot-scale module was equipped with a 10-kDa polyethersulfone spiral-wound membrane element with a surface area of 2.04m². Permeation flux, resistance-in-series model, mineral and protein rejection, and energy consumption were studied as a function of temperature and transmembrane pressure applied. Higher permeation flux values were systematically obtained at 50°C. Also, a significant temperature effect was found for calcium rejection, which was lower at 10°C compared with 50°C. Total hydraulic resistance and reversible fouling resistance were higher at 50°C than at 10°C. No change in protein rejection was observed, depending on the operating mode studied. Permeation flux, which was higher at 50°C, had lower pumping energy consumption compared with ultrafiltration at the colder temperature. Also, the low ultrafiltration temperature required a higher total energy consumption to reach the 3.6× retentate compared with ultrafiltration at 50°C. Overall, our study shows that the operating parameters and temperature can be optimized using an energy efficiency ratio.

Mutation Update of the CLCN5 Gene Responsible for Dent Disease 1

Dent disease is a rare X-linked tubulopathy characterized by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressive renal failure, and variable manifestations of other proximal tubule dysfunctions. It often progresses over a few decades to chronic renal insufficiency, and therefore molecular characterization is important to allow appropriate genetic counseling. Two genetic subtypes have been described to date: Dent disease 1 is caused by mutations of the CLCN5 gene, coding for the chloride/proton exchanger ClC-5; and Dent disease 2 by mutations of the OCRL gene, coding for the inositol polyphosphate 5-phosphatase OCRL-1. Herein, we review previously reported mutations (n = 192) and their associated phenotype in 377 male patients with Dent disease 1 and describe phenotype and novel (n = 42) and recurrent mutations (n = 24) in a large cohort of 117 Dent disease 1 patients belonging to 90 families. The novel missense and in-frame mutations described were mapped onto a three-dimensional homology model of the ClC-5 protein. This analysis suggests that these mutations affect the dimerization process, helix stability, or transport. The phenotype of our cohort patients supports and extends the phenotype that has been reported in smaller studies.

Relationship of opioid prescription sales and overdoses, North Carolina

BACKGROUND

In the United States, fatal drug overdoses have tripled since 1991. This escalation in deaths is believed to be driven primarily by prescription opioid medications. This investigation compared trends and patterns in sales of opioids, opioid drug overdoses treated in emergency departments (EDs), and unintentional overdose deaths in North Carolina (NC).

METHODS

Our ecological study compared rates of opioid sales, opioid related ED overdoses, and unintentional drug overdose deaths in NC. Annual sales data, provided by the Drug Enforcement Administration, for select opioids were converted into morphine equivalents and aggregated by zip code. These opioid drug sales rates were trended from 1997 to 2010. In addition, opioid sales were correlated and compared to opioid related ED visits, which came from a Centers for Disease Control and Prevention syndromic surveillance system, and unintentional overdose deaths, which came from NC Vital Statistics, from 2008 to 2010. Finally, spatial cluster analysis was performed and rates were mapped by zip code in 2010.

RESULTS

Opioid sales increased substantially from 1997 to 2010. From 2008 to 2010, the quarterly rates of opioid drug overdoses treated in EDs and opioid sales correlated (r=0.68, p=0.02). Specific regions of the state, particularly in the southern and western corners, had both high rates of prescription opioid sales and overdoses.

CONCLUSIONS

Temporal trends in sales of prescription opioids correlate with trends in opioid related ED visits. The spatial correlation of opioid sales with ED visit rates shows that opioid sales data may be a timely way to identify high-risk communities in the absence of timely ED data.

Adjuvant treatment of recalcitrant bullous pemphigoid with immunoadsorption

Elimination of pathogenic autoantibodies by immunoadsorption (IA) has been described as an effective adjuvant treatment in severe bullous autoimmune diseases, especially in pemphigus. There is much less experience in the treatment of bullous pemphigoid (BP). BP was diagnosed in a 62-year-old Caucasian woman presenting a pruritic rash with multiple tense blisters. Standard treatments with topical and oral corticosteroids, steroid-sparing agents including dapsone, azathioprine, mycophenolate mofetil (MMF) and intravenous immunoglobulins were ineffective or had to be discontinued due to adverse events. An immediate clinical response could be achieved by two treatment cycles of adjuvant protein A immunoadsorption (PA-IA) in addition to continued treatment with MMF (2 g/day) and prednisolone (1 mg/kg/day). Tolerance was excellent. Clinical improvement remained stable after discontinuation of IA and went along with sustained reduction of circulating autoantibodies. Our data demonstrate that PA-IA might be a safe and effective adjuvant treatment in severe and recalcitrant BP.

[Dyskeratosis congenita in a 40-year-old patient]

A 40-year-old patient with a 3-year history of thrombocytopenia was admitted with reticulated and speckled hyper- and hypopigmentations especially on the upper trunk. Aplasia or dystrophy of the fingernails and toenails as well as atresia of the lacrimal ducts were noted. Examination of the oropharynx revealed multiple mucosal leukoplakias and loss of almost all teeth. Based on these observations the diagnosis of X-linked dyskeratosis congenita (Zinsser-Cole-Engman syndrome, OMIM #305000) was made and confirmed by sequencing of the dyskerin 1 (DKC1) gene which revealed a missense mutation in exon 11.

Rituximab in autoimmune bullous diseases: mixed responses and adverse effects

BACKGROUND

Intolerably high doses of systemic corticosteroids and additional immunosuppressants may be required to control disease activity in autoimmune bullous skin diseases. New therapeutic options are needed for such patients.

OBJECTIVES

To determine the efficacy and adverse effects of adjuvant rituximab.

METHODS

Seven patients with refractory autoimmune blistering diseases (pemphigus vulgaris, PV, n = 4; bullous pemphigoid, BP, n = 2; mucous membrane pemphigoid, MMP, n = 1) were treated four times with rituximab at an individual dose of 375 mg m(-2) at weekly intervals.

RESULTS

All lesions cleared in three patients (two PV, one BP), while they were reduced by more than 50% in three others (two PV, one BP). The concomitant immunosuppressive medication was reduced in five patients (four PV, one BP). The patient with MMP developed bilateral blindness while nasopharyngeal lesions resolved. Three patients (two BP, one PV) experienced severe adverse events including fatal pneumonia.

CONCLUSIONS

Adjuvant B-cell depletion by rituximab is effective in otherwise therapy-resistant bullous autoimmune disorders but may be associated with substantial adverse effects including fatal outcomes.

Elevated serum levels of calcium-binding S100 proteins A8 and A9 reflect disease activity and abnormal differentiation of keratinocytes in psoriasis

BACKGROUND

The expression of calcium-binding S100 molecules organized within the epidermal differentiation complex on chromosome 1q21 is disturbed in hyperproliferative skin diseases such as psoriasis.

OBJECTIVES

We studied whether serum levels of S100 proteins A8 (S100A8) and A9 (S100A9) are elevated in psoriasis, correlated their amounts with disease activity and identified potential cellular sources.

METHODS

Serum obtained from psoriasis patients or from healthy individuals was studied for S100A8 and S100A9 levels by enzyme-linked immunosorbent assay. Data were correlated to disease activity as reflected by the Psoriasis Area and Severity Index (PASI). Cellular sources of S100A8 and S100A9 were identified by in situ hybridization and immunohistochemistry of lesional psoriatic and nonlesional, nonpsoriatic skin.

RESULTS

A significant increase of S100A8/S100A9 serum levels was found in patients with psoriasis compared with healthy controls. Grading the patients into two groups of severity, individuals with a PASI of <15 showed serum levels of 705+/-120 ng mL-1 (mean+/-SEM, n=18), those with a PASI of >or=15 showed levels of 1315+/-150 ng mL-1 (n=32) while controls presented with 365+/-50 ng mL-1. Performing in situ hybridization of lesional psoriatic skin we detected a dramatic induction of both S100A8 and S100A9 mRNA and protein primarily in the suprabasal layers of the epidermis while expression was negligible in nonlesional, nonpsoriatic interfollicular epidermis.

CONCLUSIONS

Our data demonstrate that hyperproliferation and abnormal differentiation of psoriatic skin is associated with a massive upregulation and secretion of S100A8 and S100A9, suggesting not only a prominent role of these molecules during intracellular calcium-dependent signalling but also implying distinct extracellular functions.

Borrelia burgdorferi bb0728 encodes a coenzyme A disulphide reductase whose function suggests a role in intracellular redox and the oxidative stress response

The cellular responses of Borrelia burgdorferiTo reactive oxygen species (ROS) encountered during the different stages of its infective cycle are poorly understood. Few enzymes responsible for protecting proteins, DNA/RNA and lipids from damage by ROS have been identified and characterized. Data presented here suggest that bb0728 encodes an enzyme involved in this process. Biochemical analyses on purified recombinant BB0728 indicated that it functioned as a coenzyme A disulphide reductase (CoADR) (specific activity approximately 26 units per mg of protein). This enzyme was specific for coenzyme A (CoA) disulphide, required NADH and had no significant activity against other disulphides, such as oxidized glutathione or thioredoxin. The high intracellular concentration of reduced CoA (CoASH) in B. burgdorferi cells ( approximately 1 mM) and absence of glutathione suggest that CoA is the major low-molecular-weight thiol in this spirochete. Interestingly, CoASH was able to reduce H(2)O(2) and be regenerated by CoADR suggesting one role for the system may be to protect B. burgdorferi from ROS. Further, mobility-shift assays and transcriptional fusion data indicated that bb0728 was positively regulated by the Borrelia oxidative stress response regulator, BosR. Taken together, these data suggest a role for BB0728 in intracellular redox and the oxidative stress response in B. burgdorferi.

Pleuro-pneumopathie à Trichomonas tenax

INTRODUCTION

Trichomonas is a protozoan rarely incriminated in pulmonary or pleural disorders.

CASE

An 84-year-old man, under treatment for chronic lymphoid leukemia with hypogammaglobulinemia, was hospitalized for respiratory distress and fever due to bilateral pulmonary and pleural disorders. Direct examination of the bronchoalveolar lavage fluid revealed a flagella protozoan identified as Trichomonas tenax.

DISCUSSION

Although Trichomonas is rare in pulmonary disorders, when it occurs, T. tenax appears to be the most common species. Treatment with metronidazole was effective.

Requirement of hydD, hydE, hypC and hypE genes for hydrogenase activity in Helicobacter pylori

Helicobacter pylori possesses a membrane-bound, nickel containing, hydrogen uptake hydrogenase enzyme; its synthesis requires structural as well as accessory proteins, the latter needed for the complete maturation of the enzyme. Our lab previously characterized mutants in the accessory hyp genes, hypA, hypB, hypD and hypF that were all severely affected for hydrogenase activity, and in some cases (hypA and hypB mutants) also affected for urease activity. This finding prompted us to disrupt the two remaining unstudied hyp genes of H. pylori, hypC and hypE, in order to see if the same pleiotropic effect would be observed. In both mutants hydrogenase activity was abolished but urease activity remained unaffected. Addition of 5 microM nickel into the growth medium partially restored the hydrogenase activity in the hypE mutant and to a lesser extent in the hypC mutant. In addition, we also disrupted the genes HP0634 (referred as hydD in the H. pylori 26695 genome database) and HP0635 (whose function was unknown, referred to here as hydE) to address their possible roles in the hydrogenase synthesis/maturation process. In both cases, hydrogenase activities were abolished and addition of nickel could not restore the activity, suggesting that these proteins are involved in the hydrogenase synthesis process rather than in nickel mobilization/insertion steps.

Treatment of recalcitrant pustular psoriasis with infliximab: effective reduction of chemokine expression

Tumour necrosis factor (TNF)-alpha is thought to play a major role in the pathophysiology of psoriasis. Good clinical responses of psoriasis to anti-TNF-alpha-based therapies have recently been demonstrated. We studied the effect of infliximab, a monoclonal antibody against TNF-alpha, on chemokine expression in pustular psoriasis. A 61-year-old man with a 2-year history of severe pustular psoriasis of von Zumbusch type who did not respond to conventional therapies responded rapidly to treatment with infliximab. The clinical response was reflected by an immediate and effective reduction of the neutrophil-attractant chemokines interleukin (IL)-8 and growth-related oncogene (Gro)-alpha as well as of monocyte chemoattractant protein (MCP)-1, as determined by mRNA in situ hybridization of lesional skin. No expression before or after treatment was seen for monokine induced by interferon (IFN)-gamma (MIG) and IFN-inducible protein (IP)-10. Thus, in pustular psoriasis the chemokine expression pattern is dominated by neutrophil-attractant chemokines and MCP-1 while, in contrast to plaque psoriasis, IFN-gamma-inducible lymphocyte-attractant chemokines such as IP-10 and MIG are not abundant. We conclude that anti-TNF-alpha treatment with infliximab is an effective therapy in severe pustular psoriasis which is reflected by downregulation of disease-promoting chemokines such as IL-8, Gro-alpha and MCP-1.

Roles of conserved nucleotide-binding domains in accessory proteins, HypB and UreG, in the maturation of nickel-enzymes required for efficient Helicobacter pylori colonization

Helicobacter pylori synthesizes two nickel-containing enzymes (urease and hydrogenase), both of which are important pathogenesis factors. Among the many accessory proteins needed for maturation of these Ni-enzymes, are two proteins, HypB and UreG, each of which contain a conserved nucleotide-binding domain (GSGKT). To address the role of this domain in the maturation process, site-directed mutations were introduced in both hypB and ureG. The hypB site-directed mutant strain (Lys59 to Ala59) lacked hydrogenase activity and had less than 1% of the parental urease activity. Hydrogenase activity was partially, and urease activity was fully restored in the hypB mutant strain when grown on nickel supplemented media. The hydrogenase activity of the ureG site-directed mutant strain (Lys14 to Ala14) was comparable to that of the parental strain. However, the ureG mutant strain lacked urease activity, and this deficiency could not be suppressed even when the strain was grown on nickel supplemented media. The expression of immunologically detectable HypB and UreG in the mutants was similar to the parental strain. Expression of the UreA and UreB subunits of urease in both the mutants was also normal. Purified UreG parental and mutant (Lys14 to Ala14) proteins had molecular masses of 27 kDa, but possessed negligible GTP hydrolyzing activity.

Dependence of Helicobacter pylori urease activity on the nickel-sequestering ability of the UreE accessory protein

The Helicobacter pylori ureE gene product was previously shown to be required for urease expression, but its characteristics and role have not been determined. The UreE protein has now been overexpressed in Escherichia coli, purified, and characterized, and three altered versions were expressed to address a nickel-sequestering role of UreE. Purified UreE formed a dimer in solution and was capable of binding one nickel ion per dimer. Introduction of an extra copy of ureE into the chromosome of mutants carrying mutations in the Ni maturation proteins HypA and HypB resulted in partial restoration of urease activity (up to 24% of the wild-type levels). Fusion proteins of UreE with increased ability to bind nickel were constructed by adding histidine-rich sequences (His-6 or His-10 to the C terminus and His-10 as a sandwich fusion) to the UreE protein. Each fusion protein was overexpressed in E. coli and purified, and its nickel-binding capacity and affinity were determined. Each construct was also expressed in wild-type H. pylori and in hypA and hypB mutant strains for determining in vivo urease activities. The urease activity was increased by introduction of all the engineered versions, with the greatest Ni-sequestering version (the His-6 version) also conferring the greatest urease activity on both the hypA and hypB mutants. The differences in urease activities were not due to differences in the amounts of urease peptides. Addition of His-6 to another expressed protein (triose phosphate isomerase) did not result in stimulation of urease, so urease activation is not related to the level of nonspecific protein-bound nickel. The results indicate a correlation between H. pylori urease activity and the nickel-sequestering ability of the UreE accessory protein.

Acute renal failure as initial presentation of visceral leishmaniasis in an HIV-1-infected patient

We report the case of an HIV-infected patient who presented with acute renal failure due to visceral leishmaniasis (VL). Although renal failure is the leading cause of death in dogs, the natural reservoir of Leishmania infantum, renal involvement is usually absent in human VL. However, L. infantum can be considered a cause of renal failure in HIV-infected patients.

Plasma therapy in von Willebrand factor protease deficiency

We report a patient with relapsing hereditary hemolytic uremic syndrome (HUS) that began in the neonatal period with life-threatening jaundice and hemolytic anemia. He progressed to end-stage renal failure at 14 years of age and had a cerebrovascular accident while on dialysis. The cause of HUS was a constitutional deficiency in the von Willebrand factor cleaving protease. Hematological features of HUS significantly improved following bilateral nephrectomy. After renal transplantation, he had an early recurrence of HUS associated with two episodes of retinal and cerebral ischemia. Long-term treatment with fresh-frozen plasma exchanges prevented recurrence of HUS, cerebrovascular attacks, and early loss of the graft.

Treponema pallidum 3-phosphoglycerate mutase is a heat-labile enzyme that may limit the maximum growth temperature for the spirochete

In the causative agent of syphilis, Treponema pallidum, the gene encoding 3-phosphoglycerate mutase, gpm, is part of a six-gene operon (tro operon) that is regulated by the Mn-dependent repressor TroR. Since substrate-level phosphorylation via the Embden-Meyerhof pathway is the principal way to generate ATP in T. pallidum and Gpm is a key enzyme in this pathway, Mn could exert a regulatory effect on central metabolism in this bacterium. To study this, T. pallidum gpm was cloned, Gpm was purified from Escherichia coli, and antiserum against the recombinant protein was raised. Immunoblots indicated that Gpm was expressed in freshly extracted infective T. pallidum. Enzyme assays indicated that Gpm did not require Mn(2+) while 2,3-diphosphoglycerate (DPG) was required for maximum activity. Consistent with these observations, Mn did not copurify with Gpm. The purified Gpm was stable for more than 4 h at 25 degrees C, retained only 50% activity after incubation for 20 min at 34 degrees C or 10 min at 37 degrees C, and was completely inactive after 10 min at 42 degrees C. The temperature effect was attenuated when 1 mM DPG was added to the assay mixture. The recombinant Gpm from pSLB2 complemented E. coli strain PL225 (gpm) and restored growth on minimal glucose medium in a temperature-dependent manner. Increasing the temperature of cultures of E. coli PL225 harboring pSLB2 from 34 to 42 degrees C resulted in a 7- to 11-h period in which no growth occurred (compared to wild-type E. coli). These data suggest that biochemical properties of Gpm could be one contributing factor to the heat sensitivity of T. pallidum.

Induction of vap genes encoded by the virulence plasmid of Rhodococcus equi during acid tolerance response

The response of the intracellular pathogen Rhodococcus equi to acid shock, a stress potentially encountered after phagocytosis by macrophages, was analyzed. The wild-type and its avirulent plasmid-cured strain acquired increased acid tolerance during the exponential growth phase upon exposure to sublethal acid stress, a response referred to as the acid tolerance response. Maximal adaptation was observed when cells were pretreated for 90 min at pH 5.0 before exposure to the pH challenge. Search for plasmid-encoded proteins regulated by an acidic pH was performed using two-dimensional gel electrophoresis, and enabled us to detect several membrane and cytoplasmic proteins with altered expression during the adaptation phase, but none of them were plasmid-encoded. However, using a strategy based on plasmid-encoded gene expression, we showed that two operons located on the virulence plasmid of strain 85F were upregulated by acid pHs with a maximal induction at pH 5.0. One operon, containing vapA, was monocistronic whereas the other was polycistronic composed of vapD and an unknown open reading frame. Our combined results suggest that these genes may play an important role in the pathogenicity of R. equi.

CNS melanocortin system involvement in the regulation of food intake

Accumulating evidence indicates that the central melanocortin (MC) system plays a key role in the regulation of food intake and energy balance. This evidence includes findings that either spontaneous genetic mutations or targeted gene deletions that impair melanocortin signaling cause disrupted food intake and body-weight control. In addition, expression of the mRNA that encodes the endogenous agonists and antagonists for CNS melanocortin receptors is regulated by changes in energy balance and body-adiposity signals. Finally, administration of both natural and synthetic ligands to MC receptors produces changes in food intake. The data collectively suggest a critical role for melanocortin signaling in the control of energy balance.

Resistance of Rhodococcus equi to acid pH

Rhodococcus equi is an important gram-positive intracellular facultative pathogen in foals of less than 3 months of age, that causes suppurative bronchopneumonia, lymphadenitis and/or enteritis. The disease in young foals mainly occurs in spring and summer when weather conditions are favorable for survival and multiplication of the bacteria in the environment. R. equi is widespread in the environment of horsebreeding farms: it has been isolated from the soil of paddocks and from the feces of adult horses and foals. Aerosol infection via dust of paddocks seems to be the major route of foal infections. The molecular mechanisms associated with the pathogenesis are not well understood and little is known about the markers or factors associated with virulence of R. equi. However, the discovery of a large plasmid in virulent strains and its association with virulence in mice and in young foals was reported. In this report, we studied the acid resistance of virulent R. equi in comparison with its avirulent plasmid-free isogene.

Enoxaparin, a low molecular weight heparin, inhibits platelet-dependent prothrombinase assembly and activity by factor-Xa neutralization

BACKGROUND

The available evidence suggests strongly that intravascular thrombosis is mediated predominantly by tissue-factor and its activation of factor X, which in the presence of factor Va, calcium, and phospholipid (prothrombinase complex) effectively converts prothrombin to thrombin. In vitro experiments have shown that low molecular weight heparins (LMWHs) have greater anti-Xa activity than unfractionated heparin; however, it remains unclear as to whether their antithrombotic effects in vivo are determined by a similar mechanism. We determined the ability of plasma obtained from patients with either unstable angina or non-ST segment elevation myocardial infarction (MI) receiving the LMWH enoxaparin (anti Xa:IIa ratio 3:1) to inhibit tissue factor-mediated thrombin generation and to inactivate platelet prothrombinase.

METHODS

Platelet rich plasma was prepared by suspending washed donor platelets in the plasma of 7 patients participating in the TIMI 11A study. Samples were obtained before, 1 hour after a 30-mg IV bolus of enoxaparin and 6 hours after the third subcutaneous injection (1. 0-1.25 mg/kg given subcutaneously every 12 hrs). Tissue factor (0.1 ng/ml) and 10 mM CaCl(2) were added to initiate extrinsic coagulation. At timed intervals prothrombin activation fragment 1.2 (F1.2) levels (thrombin generation) were measured using an ELISA technique. Inactivation of reformed platelet prothrombinase by samples obtained at the same time points was also determined.

RESULTS

Patient plasma obtained 1 hr after treatment initiation and 6 hours after the third subcutaneous injection inhibited tissue factor mediated prothrombinase assembly by 31% and 11%, respectively and platelet prothrombinase activity by 27% and 22%, respectively.

CONCLUSION

We conclude that enoxaparin in plasma concentrations achieved routinely in clinical practice is able to: (1) inhibit tissue factor mediated extrinsic coagulation by preventing platelet surface prothrombinase assembly, and (2) inactivate platelet prothrombinase activity and resulting thrombin generation. These observations suggest that a LMWH's anti-Xa activity (and anti-Xa:IIa profile) is important in determining its overall antithrombotic potential. Clinical trials comparing agents with differing anti-Xa:IIa properties will be required, however, to provide proof of concept.

The role of CNS glucagon-like peptide-1 (7-36) amide receptors in mediating the visceral illness effects of lithium chloride

Peripheral administration of large doses of lithium chloride (LiCl) to rats causes a spectrum of effects that are consistent with visceral illness. LiCl reduces food intake, decreases salt ingestion after sodium depletion, induces pica, and produces robust conditioned taste aversions. Because some of the effects of peripheral LiCl are mimicked by centrally administered glucagon-like peptide-1 (7-36) amide (GLP-1), we hypothesized that this peptide is involved in the neural pathways by which LiCl causes visceral illness. To test this hypothesis, we pretreated rats with a selective and potent GLP-1 receptor antagonist given directly into the third ventricle via an indwelling cannula before administration of peripheral LiCl. The GLP-1 receptor antagonist completely blocked the effect of LiCl to reduce food intake, induce pica, and produce a conditioned taste aversion. The same dose of GLP-1 receptor antagonist did not reverse the LiCl-induced reduction in NaCl intake. The data indicate a role for GLP-1 receptors in the CNS pathway that mediates some of the effects of visceral illness.

Nitric oxide inhibits thrombin receptor-activating peptide-induced phosphoinositide 3-kinase activity in human platelets

Although nitric oxide (NO) has potent antiplatelet actions, the signaling pathways affected by NO in the platelet are poorly understood. Since NO can induce platelet disaggregation and phosphoinositide 3-kinase (PI3-kinase) activation renders aggregation irreversible, we tested the hypothesis that NO exerts its antiplatelet effects at least in part by inhibiting PI3-kinase. The results demonstrate that the NO donor S-nitrosoglutathione (S-NO-glutathione) inhibits the stimulation of PI3-kinase associated with tyrosine-phosphorylated proteins and of p85/PI3-kinase associated with the SRC family kinase member LYN following the exposure of platelets to thrombin receptor-activating peptide. The activation of LYN-associated PI3-kinase was unrelated to changes in the amount of PI3-kinase physically associated with LYN signaling complexes but did require the activation of LYN and other tyrosine kinases. The cyclic GMP-dependent kinase activator 8-bromo-cyclic GMP had similar effects on PI3-kinase activity, consistent with a model in which the cyclic nucleotide mediates the effects of NO. Additional studies showed that wortmannin and S-NO-glutathione have additive inhibitory effects on thrombin receptor-activating peptide-induced platelet aggregation and the surface expression of platelet activation markers. These data provide evidence of a distinct and novel mechanism for the inhibitory effects of NO on platelet function.

Topological analysis of the aerobic membrane-bound formate dehydrogenase of Escherichia coli

Besides formate dehydrogenase N (FDH-N), which is involved in the major anaerobic respiratory pathway in the presence of nitrate, Escherichia coli synthesizes a second isoenzyme, called FDH-O, whose physiological role is to ensure rapid adaptation during a shift from aerobiosis to anaerobiosis. FDH-O is a membrane-bound enzyme complex composed of three subunits, alpha (FdoG), beta (FdoH), and gamma (FdoI), which exhibit high sequence similarity to the equivalent polypeptides of FDH-N. The topology of these three subunits has been studied by using blaM (beta-lactamase) gene fusions. A collection of 47 different randomly generated Fdo-BlaM fusions, 4 site-specific fusions, and 3 sandwich fusions were isolated along the entire sequence of the three subunits. In contrast to previously reported predictions from sequence analysis, our data suggested that the alphabeta catalytic dimer is located in the cytoplasm, with a C-terminal anchor for beta protruding into the periplasm. As expected, the gamma subunit, which specifies cytochrome b, was shown to cross the cytoplasmic membrane four times, with the N and C termini exposed to the cytoplasm. Protease digestion studies of the 35S-labelled FDH-O heterotrimer in spheroplasts add further support to this model. Consistently, prior studies regarding the bioenergetic function of formate dehydrogenase provided evidence for a mechanism in which formate is oxidized in the cytoplasm.