Novel sequence variants in the TMC1 gene in Pakistani families with autosomal recessive hearing impairment

Though many hearing impairment genes have been identified, only a few of these genes have been screened in population studies. For this study, 168 Pakistani families with autosomal recessive hearing impairment not due to mutations in the GJB2 (Cx26) gene underwent a genome scan. Two-point and multipoint parametric linkage analyses were carried out. Twelve families had two-point or multipoint LOD scores of 1.4 or greater within the transmembrane cochlear expressed gene 1 (TMC1) region and were subjected to further screening with direct DNA sequencing. Five novel putatively functional non-synonymous sequence variants, c.830A>G (p.Y277C), c.1114G>A (p.V372M), c.1334G>A (p.R445H), c.2004T>G (p.S668R), and c.2035G>A (p.E679K), were found to segregate within seven families, but were not observed in 234 Pakistani control chromosomes. The variants c.830A>G (p.Y277C), c.1114G>A (p.V372M), and c.1334G>A (p.R445H) occurred at highly conserved regions and were predicted to lie within hydrophobic transmembrane domains, while non-synonymous variants c.2004T>G (p.S668R) and c.2035G>A (p.E679K) occurred in extracellular regions that were not highly conserved. There is evidence that the c.2004T>G (p.S668R) variant may have occurred at a phosphorylation site. One family has the known splice site mutation c.536 -8T>A. The prevalence of non-syndromic hearing impairment due to TMC1 in this Pakistani population is 4.4% (95%CI: 1.9, 8.6%). The TMC1 protein might have an important function in K(+) channels of inner hair cells, which would be consistent with the hypothetical structure of protein domains in which sequence variants were identified.     

Differences in regional wash-in and wash-out time constants for xenon-CT ventilation studies

Xenon-enhanced computed tomography (Xe-CT) has been used to measure regional ventilation by determining the wash-in (WI) and wash-out (WO) rates of stable Xe. We tested the common assumption that WI and WO rates are equal by measuring WO-WI in different anatomic lung regions of six anesthetized, supine sheep scanned using multi-detector-row computed tomography (MDCT). We further investigated the effect of tidal volume, image gating (end-expiratory EE versus end-inspiratory EI), local perfusion, and inspired Xe concentration on this phenomenon. RESULTS: WO time constant was greater than WI in all lung regions, with the greatest differences observed in dependent base regions. WO-WI time constant difference was greater during EE imaging, smaller tidal volumes, and with higher Xe concentrations. Regional perfusion did not correlate with WI-WO. We conclude that Xe-WI rate can be significantly different from the WO rate, and the data suggest that this effect may be due to a combination of anatomic and fluid mechanical factors such as Rayleigh-Taylor instabilities set up at interfaces between two gases of different densities.     

Cross-regulation of CD86 by CD80 differentially regulates T helper responses from Mycobacterium tuberculosis secretory antigen-activated dendritic cell subsets

We report that stimulation of Mycobacterium tuberculosis secretory antigen- and tumor necrosis factor alpha-matured BALB/c mouse bone marrow dendritic cells (BMDCs) with anti-CD80 monoclonal antibody up-regulated CD86 levels on the cell surface. Coculture of these BMDCs with na?ve, allogeneic T cells now down-regulated T helper cell type 1 (Th1) responses and up-regulated suppressor responses. Similar results were obtained with splenic CD11c(+)/CD8a(-) DCs but not to the same extent with CD11c(+)/CD8a(+) DCs. Following coculture with T cells, only BMDCs and CD11c(+)/CD8a(-) DCs and not CD11c(+)/CD8a(+) DCs displayed increased levels of surface CD86, and further, coculturing these DCs with a fresh set of T cells attenuated Th1 responses and increased suppressor responses. Not only na?ve but even antigen-specific recall responses of the Th1-committed cells were modulated by DCs expressing up-regulated surface CD86. Further analyses showed that stimulation with anti-CD80 increased interleukin (IL)-10 and transforming growth factor-beta-1 levels with a concomitant reduction in IL-12p40 and interferon-gamma levels from BMDCs and CD11c(+)/CD8a(-) DCs and to a lesser extent, from CD11c(+)/CD8a(+) DCs. These results suggest that cross-talk between costimulatory molecules differentially regulates their relative surface densities leading to modulation of Th responses initiated from some DC subsets, and Th1-committed DCs such as CD11c(+)/CD8a(+) DCs may not allow for such modulation. Cognate antigen-presenting cell (APC):T cell interactions then impart a level of polarization on APCs mediated via cross-regulation of costimulatory molecules, which govern the nature of subsequent Th responses.     

Therapeutic versus neuroinflammatory effects of passive immunization is dependent on Aβ/amyloid burden in a transgenic mouse model of Alzheimer's disease

Background

Passive immunization with antibodies directed to Aβ decreases brain Aβ/amyloid burden and preserves memory in transgenic mouse models of Alzheimer's disease (AD). This therapeutic strategy is under intense scrutiny in clinical studies, but its application is limited by neuroinflammatory side effects (autoimmune encephalitis and vasogenic edema).

Methods

We intravenously administered the monoclonal Aβ protofibril antibody PFA1 to aged (22 month) male and female 3 × tg AD mice with intermediate or advanced AD-like neuropathologies, respectively, and measured brain and serum Aβ and CNS cytokine levels. We also examined 17 month old 3 × tg AD female mice with intermediate pathology to determine the effect of amyloid burden on responses to passive immunization.

Results

The 22 month old male mice immunized with PFA1 had decreased brain Aβ, increased serum Aβ, and no change in CNS cytokine levels. In contrast, 22 month old immunized female mice revealed no change in brain Aβ, decreased serum Aβ, and increased CNS cytokine levels. Identical experiments in younger (17 month old) female 3 × tg AD mice with intermediate AD-like neuropathologies revealed a trend towards decreased brain Aβ and increased serum Aβ accompanied by a decrease in CNS MCP-1.

Conclusions

These data suggest that passive immunization with PFA1 in 3 × tg AD mice with intermediate disease burden, regardless of sex, is effective in mediating potentially therapeutic effects such as lowering brain Aβ. In contrast, passive immunization of mice with a more advanced amyloid burden may result in potentially adverse effects (encephalitis and vasogenic edema) mediated by certain proinflammatory cytokines.     

Antidiabetic and haematinic effects of Parquetina nigrescens on alloxan induced type-1 diabetes and normocytic normochromic anaemia in Wistar rats

Background

The plant, Parquetina nigrescens is used in folklore medicine to treat diabetes mellitus and its complications in several parts of West Africa.

Objective

To determine the effect of Parquetina nigrescens extract on fasting blood glucose in alloxan-induced diabetic rats.

Methods

The blood glucose levels, complete blood count, erythrocyte indices and osmotic fragility, body and organ weights were evaluated.

Results

Diabetic rats treated with the extract showed significant (P<0.01) reduction of the blood glucose to levels comparable to that of the non-diabetic control and those treated with chlorpropamide (standard drug). Similarly, there was significant (P<0.01) reduction in the complete blood count in the diabetic rats.

Discussion

The anaemia, leucopenia and thrombocytopenia associated with the diabetes were corrected in the animals treated with the extract and chlorpropamide. The extract also reduced the erythrocyte osmotic fragility, body and organ weights. Parquetina nigrescens demonstrated antidiabetic property by reducing the elevated blood glucose in alloxan treated rats which is comparable to animals that received the standard drug.

Conclusion

Paraquetina nigrescens stabilized the erythrocyte membrane, decreased the body weight probably by lowering lipogenesis. However, the mechanism underlying the antidiabetic and haematinic properties of Parquetina nigrescens remains to be elucidated.     

Enhanced functions of vascular cells on nanostructured Ti for improved stent applications

Vascular tissue possesses numerous nanostructured surface features, but most metallic vascular stents proposed to restore blood flow are smooth at the nanoscale. Thus, the objective of the present study was to determine in vitro vascular cell functions on nanostructured titanium (Ti) compared to conventional commercially pure (c.p.) Ti. Results of this study showed for the first time greater competitive adhesion of endothelial versus vascular smooth muscle cells on nanostructured Ti compared to conventional Ti after 4 hours. Moreover, when cultured separately, increased endothelial and vascular smooth muscle cell density was observed on nanostructured Ti compared to conventional c.p. Ti after 1, 3, and 5 days; endothelial cells formed confluent monolayers before vascular smooth muscle cells on nanostructured Ti. Results also showed greater total amounts of collagen and elastin synthesis by vascular cells when cultured on nanostructured Ti. Since a major mode of failure of conventional vascular stents is the overgrowth of smooth muscle cells compared to endothelial cells, these results suggest that while the functions of both types of vascular cells were promoted on nanostructured c.p. Ti, endothelial cell functions (of particular importance, cell density or confluence) were enhanced over that of vascular smooth muscle cells. Thus, the present in vitro study showed that vascular stents composed of nanometer c.p. Ti particles may invoke advantageous cellular responses for improved stent applications.     

Malignant peritoneal mesothelioma presented as peritoneal adenocarcinoma or primary ovarian cancer: case series and review of the clinical and immunohistochemical features

Diffuse peritoneal malignant mesothelioma is a rare, progressive, and ultimately fatal disease and it can present as primary peritoneal carcinoma or ovarian cancer. Differential diagnosis is important to establish appropriate management. In this article the clinical presentation, immunuhistochemical and histopathological features of 8 diffuse peritoneal malignant mesothelioma cases presented as peritoneal carcinoma or ovarian cancer are evaluated. According to findings of all reported cases, we concluded that clinical distinction of malignant mesothelioma from ovarian cancer or peritoneal adenocarcinoma is very difficult. Differential diagnosis is reliably achieved by immune profile of the tumors with a systematic approach of both positive and negative mesothelioma markers.     

The structure of the avian fast skeletal muscle troponin T gene: seven novel tandem-arranged exons in the exon x region

To elucidate the mechanism that produces enormous molecular diversity in troponin T (TnT) of fast skeletal muscle, we determined the 5-half genomic sequence of the chicken fast muscle TnT gene. The sequence of ca. 16 kb included seven exons (exons 1, 2, 3, 4, w, 5, and 6), which have been reported previously and presumed by sequencing TnT cDNAs. Additionally we found six 15 nt and one 18 nt sequences in the region between exons 5 and 6 (i.e. the exon x region). They were encompassed by consensus splice donor and acceptor sites and preceded by putative branch sites, and designated herein as exons xa to xg. Our result shows that the sequence derived from exons x1, x2, and x3, the exons presumed previously by cDNA sequencing, is actually encoded by the seven exons xa to xg, establishing the precise gene structure in the exon x region. Based on our data, together with that on the 3-half genomic sequence of the quail fast muscle TnT gene, we conclude that the avian fast skeletal muscle TnT gene includes 27 exons, 16 of which are alternatively spliced.     

Lanthanides stimulate [3H]tyramine binding in the rat striatum

Low (up to 100 nM) and high (approximately 100 microM) concentrations of lanthanides and Ca2+-ions, respectively, stimulated [3H]tyramine binding ([3H]TY) to rat striatal membranes, a putative marker for the vesicular transporter of dopamine. On the other hand, lanthanides (approximately 100 microM) inhibited or stimulated TY binding in striatal and extrastriatal (cortex, cerebellum) tissues, respectively. The binding increases by lanthanum (La3+) appeared to depend on endogenous Ca2+, whereas, those induced in EDTA-pretreated membranes were Ca2+-independent. The La3+-induced, apparent increase in the Bmax for [3H]TY binding seemed to reflect a retarded rate of dissociation of the ligand from its targets, rather than a larger availability of functionally-relevant, vesicular transport-related TY sites. This indicates uncertain mechanisms of present La3+ effects.