Wolbachia effects in natural populations of Chorthippus parallelus from the Pyrenean hybrid zone.

We evaluate for the first time the effect of Wolbachia infection, involving two different supergroups, on the structure and dynamics of the hybrid zone between two subspecies of Chorthippus parallelus (Orthoptera) in the Pyrenees. Wolbachia infection showed no effects on female fecundity or a slight increment in females infected by F supergroup, although in the last case it has to be well established. Cytoplasmic incompatibility (CI) is confirmed in crosses carried out in the field between individuals from a natural hybrid population. This CI, registered as the relative reduction in embryo production (sh ), was of sh = 0.355 and sh = 0.286 in unidirectional crosses involving B and F supergroups, respectively. CI also occurred in bidirectional crosses (sh = 0.147) but with a weaker intensity. The transmission rates of the two Wolbachia strains (B and F) were estimated by the optimization of a theoretical model to reach the infection frequencies observed in certain population. To fit this scenario, both supergroups should present transmission rates close to 1. Further, we have simulated the infection dynamics, and hence, the capacity of Wolbachia to structure the population of the host insects and to affect to reproduction and genetic introgression in the hybrid zone. This represents a first example of the influence of Wolbachia in an insect natural hybrid zone.

New insight into Wolbachia epidemiology: its varying incidence during the host life cycle can alter bacteria spread.

Wolbachia is an obligate endosymbiont whose spread depends mainly on its capacity to alter host reproduction by, for instance, cytoplasmic incompatibility. Several mathematical models have been developed to explain the dynamics of bacterial spread, because of its applied interest. However, some aspects of the host's and bacterium's biology have not been considered in modelling: for instance, changes in Wolbachia proportions during the host's life cycle have been observed in several species, including Drosophila sp., Nasonia sp. and Aedes sp. (Diptera), but also in the grasshopper Chorthippus parallelus (Orthoptera), the species studied in this article. These changes influence the proportion of incompatible crosses and, consequently, infection prevalence in subsequent generations. In this paper, we are interested in ascertaining whether these changes in the infection proportions during the host's life cycle can influence the dynamics of the spread of these bacteria. We have examined its consequences using a mathematical model to predict the evolution of Wolbachia infection frequencies. The simulations were validated by experimental field data from C. parallelus. The main outcome is that those changes above mentioned might affect long-term infection spread, with possible consequences for the current distribution of Wolbachia and the way it affects its host's reproduction.

Wolbachia induced cytogenetical effects as evidenced in Chorthippus parallelus (Orthoptera).

The cytoplasmic incompatibility induced by the bacterial endosymbiont Wolbachia is attributed to chromatin modification in the sperm of infected individuals and is only 'rescued' by infected females after fertilization. Chorthippus parallelus is a grasshopper with 2 subspecies that form a hybrid zone in the Pyrenees in which this Wolbachia-generated cytoplasmic incompatibility has recently been described. The analysis of certain cytogenetic traits (sex chromosome-linked heterochromatic bands, nucleolar organizing region expression, spermatid size and morphology, and number of chiasmata formed) in pure and hybrid Chorthippus parallelus that are infected and not infected by this bacterium indicates that the infection affects some of these traits and, in the case of the spermatids, reveals a synergism between the infection and the hybrid condition. These results are interpreted as being secondary effects of the chromatin modification induced by Wolbachia which thereby support this model of modification/rescue. The possible effects of these cytogenetic variations on affected individuals are also considered.

Detection of Spiroplasma and Wolbachia in the bacterial gonad community of Chorthippus parallelus.

We have recently detected the endosymbiont Wolbachia in multiple individuals and populations of the grasshopper Chorthippus parallelus (Orthoptera: acrididae). This bacterium induces reproductive anomalies, including cytoplasmic incompatibility. Such incompatibilities may help explain the maintenance of two distinct subspecies of this grasshopper, C. parallelus parallelus and C. parallelus erythropus, which are involved in a Pyrenean hybrid zone that has been extensively studied for the past 20 years, becoming a model system for the study of genetic divergence and speciation. To evaluate whether Wolbachia is the sole bacterial infection that might induce reproductive anomalies, the gonadal bacterial community of individuals from 13 distinct populations of C. parallelus was determined by denaturing gradient gel electrophoresis analysis of bacterial 16S rRNA gene fragments and sequencing. The study revealed low bacterial diversity in the gonads: a persistent bacterial trio consistent with Spiroplasma sp. and the two previously described supergroups of Wolbachia (B and F) dominated the gonad microbiota. A further evaluation of the composition of the gonad bacterial communities was carried out by whole cell hybridization. Our results confirm previous studies of the cytological distribution of Wolbachia in C. parallelus gonads and show a homogeneous infection by Spiroplasma. Spiroplasma and Wolbachia cooccurred in some individuals, but there was no significant association of Spiroplasma with a grasshopper's sex or with Wolbachia infection, although subtle trends might be detected with a larger sample size. This information, together with previous experimental crosses of this grasshopper, suggests that Spiroplasma is unlikely to contribute to sex-specific reproductive anomalies; instead, they implicate Wolbachia as the agent of the observed anomalies in C. parallelus.

Treatment of diastolic dysfunction in hypertension.

Diastolic dysfunction is present in half of patients with hypertension and has been shown to be associated with increased cardiovascular morbidity and mortality, as well as the development of heart failure. With the high prevalence of hypertension and its associated complications, treatment of diastolic dysfunction in hypertension is an important and desirable goal. Angiotensin converting enzyme inhibitors and angiotensin receptor blockers have been shown to be effective in improvement of measures of diastolic function and are recommended as first-line agents in the control of hypertension in patients with diastolic heart failure. Beta-blockers, calcium channel blockers, and diuretics have also shown some efficacy in improved indices of diastolic filling. However, the independent impact of these pharmacologic interventions on prognosis and outcome in diastolic dysfunction has yet to be clarified. The Irbesartan in Heart Failure with Preserved Ejection Fraction (I-PRESERVE) study, Candesartan in Heart Failure: Assessment in Reduction of Mortality and Morbidity (CHARM-Preserved) trial and the Losartan Intervention For End-point Reduction in Hypertension (LIFE) Study all failed to show improved morbidity and mortality with these drugs although, the LIFE study showed reduced heart failure hospitalization in hypertensive patients with normal in-treatment diastolic function. The Trial Of Preserved Cardiac function heart failure with an Aldosterone anTagonist (TOPCAT) is an on-going large, international study evaluating the effect of spironolactone on cardiovascular mortality, aborted cardiac arrest, or hospitalization for diastolic heart failure. This and other studies will provide further insight into the pathophysiology and management of patients with diastolic dysfunction.

Distribution of Wolbachia infection in Chorthippus parallelus populations within and beyond a Pyrenean hybrid zone.

Two subspecies of the meadow grasshopper Chorthippus parallelus meet in a secondary hybrid zone in the Pyrenees. We have recently detected Wolbachia infection in this extensively studied species. C. p. parallelus (Cpp) and C. p. erythropus (Cpe) harbour bacteria from the B and F supergroups, but they differ noticeably in the incidence and type of infection present in their populations. We can distinguish different regional infection patterns that are associated with the distribution of pure and hybrid C. parallelus individuals. The northern pattern of low-level infection characterizes Cpp populations, whereas the southern pattern of high-level infection affects Cpe locations. These patterns converge in the hybrid zone and generate a third infection pattern featuring an extremely high degree of co-infection with the two Wolbachia types in hybrids. The distribution of Wolbachia among the studied populations encourages us to consider the possibility that this bacterium has a significant influence on the origin, maintenance and dynamics of this hybrid zone, given the reproductive alterations that are often associated with Wolbachia.

Sources of viral respiratory infections in Canadian acute care hospital healthcare personnel.

BACKGROUND: Viral respiratory illnesses are common causes of outbreaks and can be fatal to some patients. AIM: To investigate the association between laboratory-confirmed viral respiratory infections and potential sources of exposure during the previous 7 days. METHODS: In this nested case-control analysis, healthcare personnel from nine Canadian hospitals who developed acute respiratory illnesses during the winters of 2010/11-2013/14 submitted swabs that were tested for viral pathogens. Associated illness diaries and the weekly diaries of non-ill participants provided information on contact with people displaying symptoms of acute respiratory illness in the previous week. Conditional logistic regression assessed the association between cases, who were matched by study week and site with controls with no respiratory symptoms. FINDINGS: There were 814 laboratory-confirmed viral respiratory illnesses. The adjusted odds ratio (aOR) of a viral illness was higher for healthcare personnel reporting exposures to ill household members [7.0, 95% confidence interval (CI) 5.4-9.1], co-workers (3.4, 95% CI 2.4-4.7) or other social contacts (5.1, 95% CI 3.6-7.1). Exposures to patients with respiratory illness were not associated with infection (aOR 0.9, 95% CI 0.7-1.2); however, healthcare personnel with direct patient contact did have higher odds (aOR 1.3, 95% CI 1.1-1.6). The aORs for exposure and for direct patient contact were similar for illnesses caused by influenza. CONCLUSION: Community and co-worker contacts are important sources of viral respiratory illness in healthcare personnel, while exposure to patients with recognized respiratory infections is not associated. The comparatively low risk associated with direct patient contact may reflect transmission related to asymptomatic patients or unrecognized infections.

Corneal densitometry and topography in patients with primary congenital glaucoma.

OBJECTIVE: To compare corneal densitometry and topography variables in patients with primary congenital glaucoma (PCG) and healthy subjects. MATERIAL AND METHODS: Cross sectional study, consecutive recruitment with gender- and age-matched control group. Forty eyes of 40 patients in each group were studied with Pentacam corneal topography. The variables compared between the two groups were: intraocular pressure (IOP), visual acuity (VA) and Pentacam (Oculus, Wetzlar, Germany) corneal topography measurements: mean and maximum keratometry (Km, Kmax), cylinder (Cyl), anterior elevation apex (AEA), central anterior elevation (CAE), maximum anterior elevation (MAE), posterior elevation apex (PEA), central posterior elevation (CPE), maximum posterior elevation (MPE), pachymetry and anterior, mid-stromal and posterior corneal densitometry in the 0-2mm, 2-6mm, 6-10mm zones. RESULTS: Significant differences between patients and healthy controls were detected in the topographic variables MAE (P=0.002) and MPE (P<0.001), and in all the densitometry variables (anterior, mid-stromal, posterior for the 0-2mm, 2-6mm and 6-10mm zones) (P<0.001 each). In the PCG group, negative correlation was observed between VA and total densitometry (r=-0.49; P=0.004). CONCLUSION: Patients with PCG and healthy subjects display differences in corneal densitometry and topographic measurements. PCG patients show greater corneal density with an inverse relationship between visual acuity and higher elevation (anterior and posterior values).

Crystal and molecular structure of a collagen-like peptide at 1.9 A resolution.

The structure of a protein triple helix has been determined at 1.9 angstrom resolution by x-ray crystallographic studies of a collagen-like peptide containing a single substitution of the consensus sequence. This peptide adopts a triple-helical structure that confirms the basic features determined from fiber diffraction studies on collagen: supercoiling of polyproline II helices and interchain hydrogen bonding that follows the model II of Rich and Crick. In addition, the structure provides new information concerning the nature of this protein fold. Each triple helix is surrounded by a cylinder of hydration, with an extensive hydrogen bonding network between water molecules and peptide acceptor groups. Hydroxyproline residues have a critical role in this water network. The interaxial spacing of triple helices in the crystal is similar to that in collagen fibrils, and the water networks linking adjacent triple helices in the crystal structure are likely to be present in connective tissues. The breaking of the repeating (X-Y-Gly)n pattern by a Gly-->Ala substitution results in a subtle alteration of the conformation, with a local untwisting of the triple helix. At the substitution site, direct interchain hydrogen bonds are replaced with interstitial water bridges between the peptide groups. Similar conformational changes may occur in Gly-->X mutated collagens responsible for the diseases osteogenesis imperfecta, chondrodysplasias, and Ehlers-Danlos syndrome IV.

X-ray crystallographic structure of the Norwalk virus capsid.

Norwalk virus, a noncultivatable human calicivirus, is the major cause of epidemic gastroenteritis in humans. The first x-ray structure of a calicivirus capsid, which consists of 180 copies of a single protein, has been determined by phase extension from a low-resolution electron microscopy structure. The capsid protein has a protruding (P) domain connected by a flexible hinge to a shell (S) domain that has a classical eight-stranded beta-sandwich motif. The structure of the P domain is unlike that of any other viral protein with a subdomain exhibiting a fold similar to that of the second domain in the eukaryotic translation elongation factor-Tu. This subdomain, located at the exterior of the capsid, has the largest sequence variation among Norwalk-like human caliciviruses and is likely to contain the determinants of strain specificity and cell binding.

Idiopathic intracranial hypertension associated with anaemia, secondary to antiretroviral drug in a human immunodeficiency virus positive patient.

Papilledema in a patient with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome is an alarming finding. Any condition giving rise to raised intracranial tension (ICT) can cause papilledema, and in these patients, it could be secondary to opportunistic infections like meningitis to neoplasm. We report a case of a 28-year old female with HIV on antiretroviral therapy, who presented to us, with papilledema. Her fundus examination revealed superficial hemorrhages and Roth's spots along with papilledema. Patient was diagnosed with idiopathic intracranial hypertension (IIH), and all other possible systemic associations were ruled out. Her blood tests showed severe anemia. The papilledema and retinal changes resolved with treatment of anemia. This is a rare presentation of IIH in HIV positive patient due to anemia, secondary to zidovudine adverse effect.

Integrin-collagen complex: a metal-glutamate handshake.

The recently determined crystal structure of the complex between an integrin I domain and a synthetic collagen peptide shows a collagen triple-helix engaged in specific macromolecular recognition and binding. This structure confirms a previously proposed binding mechanism for integrin I domains and has important implications for integrin activation and signalling.

Hydration structure of a collagen peptide.

BACKGROUND: The collagen triple helix is a unique protein motif defined by the supercoiling of three polypeptide chains in a polyproline II conformation. It is a major domain of all collagen proteins and is also reported to exist in proteins with host defense function and in several membrane proteins. The triple-helical domain has distinctive properties. Collagen requires a high proportion of the post-translationally modified imino acid 4-hydroxyproline and water to stabilize its conformation and assembly. The crystal structure of a collagen-like peptide determined to 1.85 Angstrum showed that these two features may be related. RESULTS: A detailed analysis of the hydration structure of the collagen-like peptide is presented. The water molecules around the carbonyl and hydroxyprolyl groups show distinctive geometries. There are repetitive patterns of water bridges that link oxygen atoms within a single peptide chain, between different chains and between different triple helices. Overall, the water molecules are organized in a semi-clathrate-like structure that surrounds and interconnects triple helices in the crystal lattice. Hydroxyprolyl groups play a crucial role in the assembly. CONCLUSIONS: The roles of hydroxyproline and hydration are strongly interrelated in the structure of the collagen triple helix. The specific, repetitive water bridges observed in this structure buttress the triple-helical conformation. The extensively ordered hydration structure offers a good model for the interpretation of the experimental results on collagen stability and assembly.

«Poppers maculopathy?¼ in Spain. A new ophthalmological disease. / «Maculopatía por poppers¼ en España. Una nueva enfermedad oftalmológica.

INTRODUCTION: The term «poppers¼ refers to products made of volatile alkyl nitrites used for recreational practices. CLINICAL CASE: 40 year old man reported blurred vision in both eyes and photophobia, and admitted regular use of «poppers¼. Best corrected visual acuity was 0.63/1 in both eyes. Bilateral yellowish vitelliform macular lesions were present in both eyes in the funduscopy, as well as a disruption of the IS/OS line in the optical coherence tomography. DISCUSSION: This is the first case of «poppers maculopathy¼ registered in Spain. Clinical findings and symptoms are similar to previous reported cases.

Effects of once-daily angiotensin-converting enzyme inhibition and calcium channel blockade-based antihypertensive treatment regimens on left ventricular hypertrophy and diastolic filling in hypertension: the prospective randomized enalapril study evaluating regression of ventricular enlargement (preserve) trial.

BACKGROUND: The Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement (PRESERVE) study was designed to test whether enalapril achieves greater left ventricular (LV) mass reduction than does a nifedipine gastrointestinal treatment system by a prognostically meaningful degree on a population basis (10 g/m(2)). METHODS AND RESULTS: An ethnically diverse population of 303 men and women with essential hypertension and increased LV mass at screening echocardiography were enrolled at clinical centers on 4 continents and studied by echocardiography at baseline and after 6- and 12-month randomized therapy. Clinical examination and blinded echocardiogram readings 48 weeks after study entry in an intention-to-treat analysis of 113 enalapril-treated and 122 nifedipine-treated patients revealed similar reductions in systolic/diastolic pressure (-22/12 versus -21/13 mm Hg) and LV mass index (-15 versus -17g/m(2), both P>0.20). No significant between-treatment difference was detected in population subsets defined by monotherapy treatment, sex, age, race, or severity of baseline hypertrophy. Similarly, there was no between-treatment difference in change in velocities of early diastolic or atrial phase transmitral blood flow. More enalapril-treated than nifedipine-treated patients required supplemental treatment with hydrochlorothiazide (59% versus 34%, P<0.001) but not atenolol (27% versus 22%, NS). CONCLUSIONS: Once-daily antihypertensive treatment with enalapril or long-acting nifedipine, plus adjunctive hydrochlorothiazide and atenolol when needed to control blood pressure, both had moderately beneficial and statistically indistinguishable effects on regression of LV hypertrophy.

Effect of type 2 diabetes mellitus on left ventricular geometry and systolic function in hypertensive subjects: Hypertension Genetic Epidemiology Network (HyperGEN) study.

BACKGROUND: Type 2 diabetes is a cardiovascular risk factor. It remains to be elucidated in a large, population-based sample whether diabetes is associated with changes in left ventricular (LV) structure and systolic function independent of obesity and systolic blood pressure (BP). METHODS AND RESULTS: Among 1950 hypertensive participants in the HyperGEN Study without overt coronary heart disease or significant valve disease, 20% (n=386) had diabetes. Diabetics were more likely to be women, black, older, and have higher BMI and waist/hip ratio than were nondiabetics. After adjustment for age and sex, diabetics had higher systolic BP, pulse pressure, and heart rate; lower diastolic BP; and longer duration of hypertension than nondiabetics. LV mass and relative wall thickness were higher in diabetic than nondiabetic subjects independent of covariates. Compared with nondiabetic hypertensives, diabetics had lower stress-corrected midwall shortening, independent of covariates, without difference in LV EF. Insulin levels and insulin resistance were higher in non-insulin-treated diabetics (n=195) than nondiabetic (n=1439) subjects (both P:<0.01). Insulin resistance positively but weakly related to LV mass and relative wall thickness. CONCLUSIONS: In a relatively healthy, population-based sample of hypertensive adults, type 2 diabetes was associated with higher LV mass, more concentric LV geometry, and lower myocardial function, independent of age, sex, body size, and arterial BP. structural and functional abnormalities in addition to, and independent of, atherosclerosis.(13) (14) In the Framingham cohort, diabetes was associated with higher LV mass in women but not men.(15) High blood pressure (BP), obesity, and abnormal lipid profile, which often coexist with diabetes, tend to be associated with preclinical cardiovascular abnormalities(16) and may contribute to the association of diabetes with cardiovascular events. Cardiac features of diabetic and nondiabetic hypertensive subjects remain incompletely described in population-based samples. Therefore, we compared clinical and metabolic characteristics, LV geometry, and systolic function between diabetic and nondiabetic hypertensive participants in the Hypertension Genetic Epidemiology Network (HyperGEN) Study.