Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303

Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar orbital phase, which suggests that the emission is periodic. The strongest gamma-ray emission is not observed when the two stars are closest to one another, implying a strong orbital modulation of the emission or absorption processes.

Feline immunodeficiency virus: an interesting model for AIDS studies and an important cat pathogen

The lentivirus feline immunodeficiency virus (FIV) is a widespread pathogen of the domestic cat that is mainly transmitted through bites, although other means of transmission are also possible. Its prevalence ranges from 1 to 10% in different cat populations throughout the world, thus representing a large reservoir of naturally infected animals. FIV resembles the human immunodeficiency virus (HIV) in many respects. Similarities include the structural features of the virion, the general organization and great variability of the genome, the life cycle in the infected host, and most importantly, the pathogenic potential. Infection is associated with laboratory signs of immunosuppression as well as with a large variety of superinfections, tumors, and neurological manifestations. Our understanding of FIV is steadily improving and is providing important clues to the pathogenesis of immunodeficiency-inducing lentiviruses. The cellular receptor for FIV is different from the feline equivalent of the human CD4 molecule used by HIV; nevertheless, the major hallmark of infection is a progressive loss of CD4+ T lymphocytes as in HIV infection. The mechanisms by which FIV escapes the host's immune responses are being actively investigated. FIV causes lysis of infected T cells and also appears to predispose these cells to apoptosis. Infection of macrophages and other cell types has also been documented. For reasons yet to be understood, antibody-mediated neutralization of fresh FIV isolates is very inefficient both in vitro and in vivo. Vaccination studies have provided some encouraging results, but the difficulties encountered appear to match those met in HIV vaccine development. FIV susceptibility to antiviral agents is similar to that of HIV, thus providing a valuable system for in vivo preclinical evaluation of therapies. It is concluded that in many respects FIV is an ideal model for AIDS studies.

Anti-oxidant status and lipid peroxidation in patients with essential hypertension

BACKGROUND

Lipid peroxidation and derived oxidized products are being intensively investigated, because of their potential to cause injury and their pathogenetic role in several clinically significant diseases. The view that an excess of lipid peroxidation products is present and relevant in the pathogenesis of human essential hypertension or in hypertension-induced damage has still not received definitive support.

OBJECTIVE

To evaluate both the extent of lipoperoxidation in essential hypertensive patients and the status of enzymatic and non-enzymatic antioxidants that potentially are able to modulate it

METHODS

We selected 105 newly diagnosed essential hypertensives among those referred to our hypertension outpatient clinic and compared them with 100 normotensive controls matched for age. Plasma malondialdehyde was measured by high-performance liquid chromatography after reaction with thiobarbituric acid, as an end product of lipid peroxidation; serum selenium (Se), plasma copper (Cu) and zinc (Zn), vitamins A and E, erythrocyte superoxide dismutase and glutathione peroxidase levels were evaluated as indices of oxidant balance. Differences between the groups were tested by Student's t test and chi2 test.

RESULTS

Compared with controls, essential hypertension patients had higher malondialdehyde and glutathione peroxidase activities (P<0.05 for both) and Zn concentrations (P<0.001) and lower superoxide dismutase activities (P<0.005), vitamin A (P<0.05) and E (P<0.001) levels and Cu concentrations (P<0.005). We found no difference between Se levels of essential hypertensive and control subjects.

CONCLUSIONS

Essential hypertension is associated with greater than normal lipoperoxidation and an imbalance in anti-oxidant status, suggesting that oxidative stress is important in the pathogenesis of essential hypertension or in arterial damage related to essential hypertension.

The Metabolic Syndrome is an independent predictor of cardiovascular disease in Type 2 diabetic subjects. Prospective data from the Verona Diabetes Complications Study

AIMS

To evaluate the cardiovascular risk associated with the presence of the Metabolic Syndrome in Type 2 diabetic subjects.

METHODS

Subjects with the Metabolic Syndrome, defined by WHO criteria, were identified in a large sample of non-insulin-treated Type 2 diabetic patients examined within the Verona Diabetes Complications Study (n = 946). At baseline and after a mean of 4.5 years follow-up, cardiovascular disease (CVD) was assessed by medical history, physical examination, electrocardiogram (ECG) and echo-duplex of carotid and lower limb arteries. Death certificates and medical records of subjects who died during the follow-up were scrutinized in order to identify CVD deaths. In statistical analyses, CVD was considered as an aggregate end-point, including fatal and non-fatal coronary, cerebrovascular and peripheral vascular disease as well as ischaemic ECG abnormalities and vascular lesions at the echo-duplex.

RESULTS

The proportion of subjects with the Metabolic Syndrome was very high (92.3%). At the baseline, 31.7% of subjects were coded positive for CVD, which was more prevalent in subjects with the Metabolic Syndrome (32.9 vs. 17.8%, P = 0.005). Among subjects free of CVD at the baseline (n = 559), CVD events during the follow-up were significantly increased in patients with the Metabolic Syndrome as compared with those without it (19.9% vs. 3.9%, P < 0.001). Multiple logistic regression analysis showed that, along with sex, age, smoking and HbA1c, the presence of the Metabolic Syndrome independently predicted prevalent (OR 2.01, P = 0.045) and incident CVD (OR 4.89, P = 0.031).

CONCLUSIONS

In Type 2 diabetes, the presence of the Metabolic Syndrome is associated with an almost 5-fold increase in CVD risk.

Plasma glucose levels throughout the day and HbA(1c) interrelationships in type 2 diabetes: implications for treatment and monitoring of metabolic control

OBJECTIVE

To evaluate the extent of plasma glucose excursions with meals, the relations between plasma glucose levels at different times of the day, and the relations between the latter and HbA(1c) in non-insulin-treated type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Daily glucose profiles were assessed in non-insulin-treated type 2 diabetic patients. Outpatients at the diabetes clinic (n = 371; one daily plasma glucose profile) and at home (n = 30; five daily blood glucose profiles over 1 month) as well as inpatients (n = 455; profile of plasma glucose on the day of admission) were examined. Subjects had plasma/blood glucose assessment before and 2-3 h after breakfast, lunch, and dinner. HbA(1c) was also measured.

RESULTS

After the meals many subjects had glucose levels >8.9 mmol/l (160 mg/dl) and/or glucose excursions >2.2 mmol/l (40 mg/dl). This was also often found when HbA(1c) was satisfactory (<7%). The coefficients of simple correlation among plasma/blood glucose at different times of the day ranged from 0.52 to 0.88. Correlations between HbA(1c) and plasma/blood glucose at different times of the day ranged from 0.44 to 0.67. The strongest correlation was between HbA(1c) and mean daily glucose (r = 0.57-0.69). Multiple regression analyses showed that premeal but not postmeal plasma/blood glucose levels were independent predictors of HbA(1c).

CONCLUSIONS

These results suggest that 1) the majority of non-insulin-treated type 2 diabetic patients have exaggerated plasma/blood glucose excursions with meals, and many of them have higher-than-recommended glucose concentrations 2 h after the meals; 2) plasma/blood glucose levels throughout the day are not as strongly interrelated as one might believe; and 3) HbA(1c) is more related to preprandial than postprandial plasma/blood glucose levels. These findings have potential implications for treatment and monitoring of metabolic control in type 2 diabetes.

Knowledge sharing in knowledge-intensive manufacturing firms. An empirical study of its enablers

Purpose

– This paper aims to investigate, following previous studies on knowledge-sharing (KS) processes that consist of knowledge donating (KD) and knowledge collecting (KC), the relationship between KS processes and KS enablers to understand the effect of organizational, individual and technological factors.

Design/methodology/approach

– The study is based on a Web survey. Data were collected from a sample of 759 knowledge workers selected from 23 knowledge-intensive manufacturing companies exposed to international markets and located in Tuscany (Italy). The analysis is based on multivariate regression models considering KD and KC as dependent variables.

Findings

– The results show that individual, organizational and technological factors matter to KS. Specifically, the paper reports that individual-level enablers and supportive leadership have a positive effect on both sub-processes of knowledge sharing. Further, the organic management system has a strong and positive impact on KD, while the efficacy of information and communication technology solutions is positively related to KC.

Research limitations/implications

– Although based on a geographically bounded perimeter, the analysis allows some generalizations. In fact, the paper proposes a set of enablers that empirically link micro- and macro-organizational mechanisms to KS.

Practical implications

– The evidence described can help improve the organizational management of KS and, consequently, support managers dealing with organizational design aimed at successful KS.

Originality/value

– The paper presents original results by combining individual, organizational and technological variables in the explanation of KS. It could be a basis for further studies.

Prevalence and levels of antibodies to the circumsporozoite protein of Plasmodium falciparum in an endemic area and their relationship to resistance against malaria infection

A study on malaria transmission, prevalence of infection and anti-sporozoite antibodies was carried out in Burkina Faso (West Africa). The prevalence and the levels of antibodies to (NANP)3 were found to be related to the entomological sporozoite inoculation rates measured at the same time in a defined area. The major inducer of anti-(NANP)3 antibody production under field conditions is sporozoite inoculation by infected mosquitoes. Levels of antibodies to (NANP)3 vary considerably with age and transmission season. High levels of anti-(NANP)3 antibodies raised under field conditions might offer protection against small inocula of sporozoites.

A neutralizing antibody-inducing peptide of the V3 domain of feline immunodeficiency virus envelope glycoprotein does not induce protective immunity

Specific-pathogen-free cats, immunized with a 22-amino-acid synthetic peptide designated V3.3 and derived from the third variable region of the envelope glycoprotein of the Petaluma isolate of feline immunodeficiency virus (FIV), developed high antibody titers to the V3.3 peptide and to purified virus, as assayed by enzyme-linked immunoassays, as well as neutralizing antibodies, as assayed by the inhibition of syncytium formation in Crandell feline kidney cells. V3.3-immunized animals and control cats were challenged with FIV and then monitored for 12 months; V3.3 immunization failed to prevent FIV infection, as shown by virus isolation, anti-whole virus and anti-p24 immunoglobulin G antibody responses, and positive PCRs for gag and env gene fragments. Sequence analysis of the V3 region showed no evidence for the emergence of escape mutants that might have contributed to the lack of protection. The sera of the V3.3-hyperimmunized cats and two anti-V3.3 monoclonal antibodies neutralized FIV infectivity for Crandell feline kidney cells at high antibody dilutions but paradoxically failed to completely neutralize FIV infectivity at low dilutions. Moreover, following FIV challenge, V3.3-immunized animals developed a faster and higher antiviral antibody response than control cats. This was probably due to enhanced virus replication, as also suggested by quantitative PCR data.

Identification of a linear neutralization site within the third variable region of the feline immunodeficiency virus envelope

Synthetic peptides have been used to map linear B-cell epitopes of the third variable (V3) region of the feline immunodeficiency virus (FIV) external membrane glycoprotein gp120. The analysis of sera from naturally and experimentally FIV-infected cats by Pepscan and enzyme immunoassay with four partially overlapping peptides evidenced three antibody-binding domains, two of which mapped in the carboxyl-terminal half of V3. In particular, the V3.3 sequence (Gly-392-Phe-413) turned out to be important for in vitro neutralization of the virus in that the peptide inhibited the FIV-neutralizing activity of pooled immune cat sera, and on the other hand, cat sera raised against this peptide effectively neutralized FIV infectivity for Crandell feline kidney cells.

Exploring different cultural configurations: how do they affect subsidiaries’ knowledge sharing behaviors?

Purpose

– The purpose of this paper is to explore the impact of different cultural typologies (i.e. innovative, competitive, bureaucratic and community) on employees’ knowledge-sharing processes within multinational corporations (MNCs) by taking a subsidiary perspective. It particularly applies the competing values framework to the study of individuals’ orientations toward sharing knowledge with others while also investigating the influence of top management support on such orientations.

Design/methodology/approach

– To test the proposed hypotheses, in this paper, survey data of 389 employees from six Italian subsidiaries are empirically analyzed by running hierarchical regressions on the two dimensions of knowledge-sharing processes, i.e. knowledge donating and knowledge collecting.

Findings

– The results show that the four types of organizational culture differently affect the knowledge-sharing sub-processes and confirm the importance of a strong top management support to facilitate interpersonal relationships.

Research limitations/implications

– Despite the cross-sectional nature of the data and the limitations arising from the subsidiaries’ position in the country, the findings suggest managers to pay great attention to the positive side of bureaucracy by emphasizing the need for order and efficiency while, at the same time, providing employees with a constant and encouraging support toward knowledge-sharing activities.

Originality/value

– The paper adds empirical evidence to the limited existing research on knowledge-sharing sub-processes of knowledge donating and collecting, extends the understanding of how different organizational cultures affect such processes, and contributes to the literature on MNCs’ knowledge-based activities by adopting a subsidiary perspective.

IgG subclass switching and clonal expansion in cutaneous melanoma and normal skin

B cells participate in immune surveillance in human circulation and tissues, including tumors such as melanoma. By contrast, the role of humoral responses in cutaneous immunity is underappreciated. We report circulating skin-homing CD22+CLA+B cells in healthy volunteers and melanoma patients (n = 73) and CD22+ cells in melanoma and normal skin samples (n = 189). Normal and malignant skin featured mature IgG and CD22 mRNA, alongside mRNA for the transiently-expressed enzyme Activation-induced cytidine Deaminase (AID). Gene expression analyses of publically-available data (n = 234 GEO, n = 384 TCGA) confirmed heightened humoral responses (CD20, CD22, AID) in melanoma. Analyses of 51 melanoma-associated and 29 normal skin-derived IgG sequence repertoires revealed lower IgG1/IgG_total representation compared with antibodies from circulating B cells. Consistent with AID, comparable somatic hypermutation frequencies and class-switching indicated affinity-matured antibodies in normal and malignant skin. A melanoma-associated antibody subset featured shorter complementarity-determining (CDR3) regions relative to those from circulating B cells. Clonal amplification in melanoma-associated antibodies and homology modeling indicated differential potential antigen recognition profiles between normal skin and melanoma sequences, suggesting distinct antibody repertoires. Evidence for IgG-expressing B cells, class switching and antibody maturation in normal and malignant skin and clonally-expanded antibodies in melanoma, support the involvement of mature B cells in cutaneous immunity.

Predictors of insulin sensitivity in Type 2 diabetes mellitus

AIMS

To identify the independent predictors of insulin sensitivity in Type 2 diabetes, and to establish whether isolated Type 2 diabetes (i.e. diabetes without overweight, dyslipidaemia and hypertension) is a condition of insulin resistance.

METHODS

We examined 45 patients with non-insulin-treated Type 2 diabetes undergoing a 4-h euglycaemic hyperinsulinaemic clamp (20 mU/m2 per min) combined with 3H-3-D-glucose and 14C-U-glucose infusions and indirect calorimetry. We also examined 1366 patients with non-insulin-treated Type 2 diabetes randomly selected among those attending the Diabetes Clinic and in whom insulin resistance was estimated by Homeostasis Model Assessment (HOMA-IR).

RESULTS

In the 45 patients undergoing glucose clamp studies, insulin-mediated total glucose disposal (TGD) was independently and negatively associated with systolic blood pressure (standardized beta coefficient = -0.407, P = 0.003), plasma triglycerides (beta= -0.355, P = 0.007), and HbA1c (beta= -0.350, P = 0.008). The overall variability of TGD explained by these variables was 53%. Overweight diabetic subjects with central fat distribution, hypertension, hypertriglyceridaemia and poor glycometabolic control had insulin-mediated TGD values markedly lower than their lean counterparts without hypertension, with normal triglycerides, and with good glycometabolic control (16 +/- 5 vs. 31 +/- 10 micromol/min per kg lean body mass, P < 0.01). Nevertheless, the latter still were markedly insulin-resistant when compared with sex- and age-matched non-diabetic control subjects (31 +/- 10 vs. 54 +/- 13 micromol/min per kg lean body mass, P < 0.01). In the 1366 Type 2 diabetic patients of the epidemiological study, HOMA-IR value was independently associated with HbA1c (beta = 0.283, P < 0.0001), plasma triglycerides (beta = 0.246, P < 0.0001), body mass index (beta = 0.139, P < 0.001), waist girth (beta = 0.124, P < 0.001) and hypertension (beta = 0.066, P = 0.006).

CONCLUSION

Overweight, central fat distribution, dyslipidaemia, hypertension and poor glycometabolic control are strong independent predictors of insulin resistance in Type 2 diabetes. However, reduced insulin sensitivity can be found even when Type 2 diabetes is isolated and well controlled.

Aldehyde dehydrogenase and estrogen receptor define a hierarchy of cellular differentiation in the normal human mammary epithelium

INTRODUCTION

Although estrogen and progesterone play a key role in normal mammary development and in breast cancer, the potential for proliferation and lineage differentiation as well as origin of cells that express the estrogen receptor (ER) in normal breast epithelium are not known. Some evidence suggests that normal human mammary stem/progenitor cells are ER-, but the identity of these cells and the cellular hierarchy of breast epithelium are still subjects of controversy. It is likely that elucidation of these aspects will bring insight into the cellular origin of breast cancer subtypes.

METHODS

We used fluorescence-activated cell sorting of primary human mammary epithelial cells along with in vitro and in vivo functional assays to examine the hierarchic relation between cells with aldehyde dehydrogenase enzymatic activity (ALDH+ cells) and ER+ cells in the normal human breast epithelium. We assessed the proliferation and lineage differentiation potential of these cells in vitro and in vivo. A gene reporter assay was used to separate live ER+ and ER- mammary epithelial cells. With shRNA-mediated knockdown, we investigated the role of ALDH isoforms in the functionality of mammary epithelial progenitor cells.

RESULTS

We describe a cellular hierarchy in the normal human mammary gland in which ER-/ALDH+ cells with functional properties of stem/progenitor cells generate ER+ progenitor cells, which in turn give rise to cells of luminal lineage. We show that the ALDH1A1 isoform, through its function in the retinoic acid metabolism, affects the proliferation and/or early differentiation of stem/progenitor cells and is important for branching morphogenesis.

CONCLUSIONS

This study presents direct evidence that ER+ cells are generated by ER-/ALDH+ stem/progenitor cells. We also show that ER+ cells are able to generate cell progeny of luminal lineage in vitro and in vivo. Loss of ALDH1A1 function impairs this process, as well as branching morphogenesis and clonogenicity in suspension culture. This latter effect is reversed by treatment with retinoic acid.

Development of the human immune response against the major surface protein (gp190) of Plasmodium falciparum

The 190-kilodalton glycoprotein (gp190) of Plasmodium falciparum, the precursor of the major surface proteins of merozoites, is considered a promising candidate for a blood stage malaria vaccine. DNA sequences specific for the gp190 of the two isolates K1 and MAD20 were subcloned and expressed in Escherichia coli. The panel of fusion proteins obtained represents about 80% of the polymorphic sequences observed so far within various isolates of P. falciparum. Sera from individuals living in a malaria-endemic area of West Africa were tested in immunoblots against the gp190 fusion proteins, and antibody reactivity was mapped to defined regions of the gp190. Depending on the age of the individual and on the presence of parasites in the blood, distinct regions of gp190 were differentially recognized by the respective antibodies. Similarly, the analysis of sera from German patients with acute malaria revealed a distinct pattern. When grouped according to age and to parasitemia, the reactivity of the sera of people living in malaria-endemic areas may indicate a correlation between certain gp190 regions and protective immune response.

Growth hormone is secreted by normal breast epithelium upon progesterone stimulation and increases proliferation of stem/progenitor cells

Using in vitro and in vivo experimental systems and in situ analysis, we show that growth hormone (GH) is secreted locally by normal human mammary epithelial cells upon progesterone stimulation. GH increases proliferation of a subset of cells that express growth hormone receptor (GHR) and have functional properties of stem and early progenitor cells. In 72% of ductal carcinoma in situ lesions, an expansion of the cell population that expresses GHR was observed, suggesting that GH signaling may contribute to breast cancer development.