Mn-induced modifications of Ga 3d photoemission from (Ga, Mn)As: evidence for long range effects

Using synchrotron based photoemission, we have investigated the Mn-induced changes in Ga 3d core level spectra from as-grown Ga(1-x)Mn(x)As. Although Mn is located in Ga substitutional sites, and therefore does not have any Ga nearest neighbors, the impact of Mn on the Ga core level spectra is pronounced even at Mn concentrations in the region of 0.5%. The analysis shows that each Mn atom affects a volume corresponding to a sphere with around 1.4 nm diameter.

Increased vascular tone due to sympathovagal imbalance in normotensive and prehypertensive offspring of hypertensive parents

AIM

Prehypertension has recently been observed as a potent cardiovascular risk factor. Though prehypertension has a strong familial predisposition, the pathophysiological mechanisms that cause its progression to prehypertension in normotensive sibling of hypertensive parents have not yet been fully elucidated. Therefore, the present study was conducted in normotensive and prehypertensive sibling by spectral analysis of heart rate variability (HRV) to understand the nature of change in sympathovagal balance (SVB) in this condition.

METHODS

Body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP) and spectral indices of HRV were assessed in three groups of subjects: Group I (normotensive offspring of normotensive parents, N.=231); Group II (normotensive offspring of hypertensive parents, N.=113); and Group III (prehypertensives offspring of hypertensive parents, N.=52). SVB was analyzed and correlated with BMI, WHR, BHR, BP and RPP in all the groups.

RESULTS

Sympathovagal imbalance (SVI) was observed to be present in both normotensive and prehypertensive sibling of hypertensive parents. In normotensive sibling, SVI was mild in the form of proportionate increase in sympathetic and decreased vagal activity. In prehypertensive sibling, SVI was prominent with more of vagal withdrawal. Though LF-HF ratio, the indicator of SVB was correlated with all parameters in groups II and III, the significance was more with diastolic pressure and WHR.

CONCLUSION

It was concluded that vagal inhibition plays a critical role in modulation of SVB for progression into prehypertension in normotensive sibling of hypertensive parents and WHR is a prominent marker of SVI in these subjects.

A report on the prevalence of gastrointestinal parasites in yaks (Bos poephagus) in the cold desert area of North Sikkim, India

Faecal samples were collected from 348 yaks(Bos poephagus) in and around Gurudogmer Plateau, a cold desert area in North Sikkim, India. The prevalence of gastrointestinal parasitic infection was recorded at 10.05% in both the organized and traditionally managed farms of yak. The pattern of infection was either single (2.58%) or mixed (7.47%) with a faecal egg count range of 100-200 eggs per gram of faeces in positive animals. Among the helminths, Haemonchus spp. infection was predominant (6.89%) followed by Nematodirus spp. (1.72%), Cooperia spp. (1.43%) and Dicrocoelium spp. (0.29%).

Multiple ways of C/EBPalpha inhibition in myeloid leukaemia

Transcription factors play a crucial role in myeloid differentiation and lineage determination. Tumour suppressor protein C/EBPalpha is a key regulator of granulocytic differentiation whose functional inactivation has become a pathophysiological signature of myeloid leukaemia. In this review we describe various mechanisms such as antagonistic protein-protein interaction, mutation and posttranslational modifications of C/EBPalpha which lead to its transcriptional inhibition and render C/EBPalpha inactive in its functions.

Minimal model for kinetic arrest

To elucidate slow dynamics in glassy materials, we introduce the figure-8 model in which N hard blocks undergo Brownian motion around a circuit in the shape of a figure 8. This system undergoes kinetic arrest at a critical packing fraction phi=phi g<1 , and for phi approximately phi g long-time diffusion is controlled by rare, cooperative, "junction-crossing" particle rearrangements. We find that the average time between junction crossings tau JC, and hence the structural relaxation time, does not simply scale with the configurational volume Omega c of transition states, because tau JC also depends on the time to complete a junction crossing. The importance of these results in understanding cage-breaking dynamics in glassy systems is discussed.

Patterns of parasitic infections in faecal samples from stray cat populations in Qatar

The parasite fauna of stray cat populations, comprising mainly helminth parasites, is described for the first time from the arid environment of the Qatar peninsula. During the winter and summer months of 2005, 824 faecal samples were examined from six sites in Qatar. Up to seven species of parasites were identified, six of which were nematodes - Strongyloides stercoralis as the most prevalent (18.4%), followed by Aelurostrongylus abstrusus (7.5%), Toxocara cati (6.1%), Ancylostoma tubaeforme (5.9%) and Physaloptera sp. (4.8%) and Toxascaris leonina (0.7%) - and one sporozoan species, Isospora felis (0.5%). Unidentified cestode eggs were also recovered from 10.7% of samples examined. The parasite species were found to be highly overdispersed in faecal samples from all sites, whereas the prevalence and intensity of infections were influenced by site and season. Infection levels tended to be higher during the winter season, especially in the case of A. abstrusus and A. tubaeforme, when conditions of temperature and humidity were more favourable for the development of egg and/or larval stages of parasites compared with the extremely hot and dry summer months. The results are discussed in relation to the distribution of the cat population in the vicinity of Doha and its outskirts and the potential threat of parasite transmission to human communities in Qatar.

Parasite aggregations in host populations using a reformulated negative binomial model

The negative binomial distribution model is reformulated and used to demarcate a host population at a specific level of infection by defining an attribute spanning a range of parasite aggregations. The upper limit of the range specifies the boundary for the classification of the host population and provides a technique to determine the cumulative probability at any level of parasite infection to a high degree of accuracy. This approach also leads to the evaluation of thekparameter, i.e. an inverse measure of dispersion of parasite aggregation, for each fraction of the host population with a discrete level of infection. The basic mathematical premise of the negative binomial function is unaltered in developing this reformulation which was applied to data on the distribution of the trichostrongylid nematodeHeligmosomoides polygyrusin populations of the field mouse,Apodemus sylvaticus.

Multiple schwannomas: report of two cases

In this paper authors present two cases of multiple schwannomas without the features of neurofibromatosis (NF). The authors retrospectively reviewed the hospital charts, radiology films, operative notes and pathology slides of these two patients. There was no family history of neurofibromatosis. The two patients had contrast enhanced MRI, which was negative for vestibular schwannomas. Both underwent surgical excision of symptomatic lesions. Histopathology confirmed these lesions as schwannomas. Molecular genetic analysis in case 1 demonstrated two distinct mutations of the NF2 gene in two different schwannomas, with concomitant loss of heterozygosity in both tumours. In contrast peripheral blood lymphocytes did not reveal mutations of NF2. The authors recommend surgery for symptomatic lesions. Asymptomatic tumours can be monitored. Regular follow up is essential as they may develop fresh lesions at any time. The relevant literature is discussed.

Expression of survivin, platelet-derived growth factor A (PDGF-A) and PDGF receptor α in primary central nervous system lymphoma

PURPOSE

Primary central nervous system lymphomas (PCNSL) are rare tumours occurring in the brain. Their biology and the factors predicting survival are not well known. This study investigated expression of the antiapoptotic protein survivin and platelet-derived growth factor A (PDGF-A) and receptor (PDGFRalpha) in PCNSL.

EXPERIMENTAL DESIGN

A total of 44 patients with histologically confirmed PCNSL treated between 1992 and 2004 were included in this study, and tumour specimens were investigated immunohistochemically for expression of survivin, PDGF-A and PDGFRalpha. Protein expression and clinical variables were analyzed statistically.

RESULTS

Of the 44 tumours 43(98%) were diffuse large B-cell non-Hodgkin's lymphomas (NHL) and one was a T-cell NHL. Around 37 (84%) of the examined PCNSL specimens showed expression of survivin, 16 (36%) of PDGF-A and 34 (77%) of PDGFRalpha. Tumours expressing surviving co-expressed PDGFRalpha frequently and PDGF-A occasionally. Expression of the above proteins was not predictive for survival in this patient group. Except for age and therapy, no other clinical variables correlated significantly with overall survival.

CONCLUSIONS

PCNSL express survivin and PDGFRalpha in the majority of investigated cases. PDGF-A is expressed less frequently. Immunohistochemical detection of these proteins does not correlate with overall survival and cannot be used as a prognostic factor.

TGFBR1*6A is not associated with prostate cancer in men of European ancestry

The TGFBR1*6A (*6A) variant in exon 1 of the TGFBR1 gene has been postulated as a putative tumor susceptibility allele in several studies. We have performed a case-control study in 537 men with histologically verified prostate cancer and in 488 unrelated controls to investigate the association of *6A with prostate cancer. Our results revealed that the frequency of the (*)6A allele does not differ in men with prostate cancer compared to healthy controls, even in a subset of age-matched cases and controls. There is no compelling evidence for an association of the *6A variant with prostate cancer.