Effect of deletions in the α-globin gene on the phenotype severity of ß-thalassemia.

Thalassemia is the most common inherited hemoglobinopathy worldwide. Variation of clinical symptoms in this hemoglobinopathy entails differences in disease-onset and transfusion requirements. The aim of this study was to investigate the role of α-globin gene deletions in modulating the clinical heterogeneity of ß-thalassemia (ß-thal) syndromes. A total number 270 ß-thal subjects were enrolled. Hematological parameters were recorded. ß-Globin mutations were determined by amplified refractory mutation system-polymerase chain reaction (ARMS-PCR), gap-PCR and Sanger sequencing. α-Globin gene deletions were determined by multiplex PCR. Out of 270 ß-thal subjects, 19 carried ß+/ß+, 74 had ß0/ß0 and 177 had the ß0/ß+ genotype. When we determined the severity of the different ß-thal subjects in coinherited with the α gene deletion, it was revealed that, 84.2% ß+/ß+ subjects carried a non severe phenotype and did not have an α gene deletion. Of the ß0/ß0 individuals, 95.9% presented a severe phenotype, irrespective of α-globin gene deletions. In cases with the ß0/ß+ genotype, 19.2% subjects also carried a deletion on the α gene. Of these, 61.8% presented a non severe phenotype and 38.2% were severely affected. Only in the ß0/ß+ category did α gene deletions make a significant contribution (p < 0.001) toward alleviation of clinical severity. Therefore, it can be stated that α-globin gene deletions play a role in ameliorating the phenotype in patients with a ß+/ß0 genotype.

An analytical approach to the effect of finite-sized end reservoirs on electroosmotic transport through narrow confinements.

The presence of end reservoirs often alters the electrical potential distributions inside narrow fluidic confinements of electrokinetically actuated miniaturized devices to a significant extent. This paper examines the influence of finite size effect of the end reservoirs on the concerned potential distribution analytically, using the Schwarz-Christoffel conformal mapping. The effective electric field directly acting across the channel is accordingly represented by a calibration curve, which sums up the role of the key geometric parameters (reservoir-to-channel height and length ratios) on the potential distribution. The analytical model is further augmented to assess the flow characteristics through the channel. The results indicate that the alterations in the flow characteristics due to alterations in the effective electric field on account of the finite size effects of the end reservoirs can turn out to be significantly more prominent than the corresponding alterations due to the axial pressure gradients induced by the sudden contraction and expansion effects associated with the end reservoirs. The derived results can be further utilized to facilitate the practical design of miniaturized fluidic devices, using conveniently tractable analytical tools.

Scaling laws for external fluid flow induced by controlled periodic heating of a solid boundary.

We demonstrate that considerable variation of mean Prandtl number (Pr_{0}) from unity brings in an additional length scale (called the viscous penetration depth, δ_{v}) into the dynamics of instantaneous as well as time-averaged (mean) flow induced by thermoviscous expansion along a periodically heated solid wall. We investigate the limiting cases of high and low Prandtl numbers (Pr_{0}≫1 and Pr_{0} â‰ª 1) through detailed order-of-magnitude analysis. Our study reveals that the viscous penetration depth scales universally with Pr_{0} so long as such depth remains small compared to the wavelength of the applied thermal wave. While a high Pr_{0} is found to obstruct the mean flow, the converse is not necessarily true. Subsequent analysis clearly shows that a low-Pr_{0} flow can induce negative thermoviscous force within the thermal boundary layer and thus retard the mean motion, leading to a nontrivial reduction of net mass flow along the plate. Numerical prediction of friction factor variation with Pr_{0} agrees well with the scaling estimates for both high-Pr_{0} and low-Pr_{0} fluids. The findings may very well act as fundamental design basis for engineering devices that may potentially be developed for thermal molecular trapping and particle sorting and accumulation based on unsteady heating.

New regimes of dispersion in microfluidics as mediated by travelling temperature waves.

We unveil new regimes of dispersion in miniaturized fluidic devices, by considering fluid flow triggered by a travelling temperature wave. When a temperature wave travels along a channel wall, it alters the density and viscosity of the adjacent fluid periodically. Successive expansion-contraction of the fluid volume through a spatio-temporally evolving viscosity field generates a net fluidic current. Based on the temporal evolution of the axial dispersion coefficient, new regimes of dispersion-such as a short-time 'oscillating regime' and a large-time 'stable regime'-have been identified, which are absent in traditionally addressed flows through miniaturized fluidic devices. Our analysis reveals that the oscillation of axial dispersion persists until the variance of species concentration becomes equal to half of the square of the wavelength of the thermal wave. The time period of oscillation in the dispersion coefficient turns out to be a unique function of the thermal wavelength and net flow velocity induced by thermoviscous pumping. The results of this study are likely to contribute towards the improvement of microscale systems that are subjected to periodic temperature variations, including microreactors and DNA amplification devices.

Role of Histomorphology and Chronic Inflammation Score in Chronic Dacryocystitis.

INTRODUCTION: Diseases of lacrimal drainage system account for nearly 3% of visits to eye clinic. Chronic dacryocystitis is a frequently encountered disorder among these patients. Histomorphology of specimens obtained after Dacryocystorhinostomy (DCR) is a pertinent indicator of prognostic outcome. AIM: The aim of the study was to evaluate histopathology of specimens obtained after DCR and to elucidate patterns and score of chronic inflammation encountered. MATERIALS AND METHODS: The study was conducted for a period of one year. Total of 50 patients who were clinically diagnosed as Chronic Dacryocystitis and underwent DCR were included. Following DCR, specimens of lacrimal sac, nasal mucous membrane and nasal bone were collected. Histopathological slides were examined for chronic inflammatory cell infiltration, fibrosis and capillary proliferation and were graded according to severity, in each specimen. A Chronic Inflammation Score (CIS) was recorded for each case. RESULTS: The average age of patients was 39.04±14.22 years and their age ranged between 13 and 62 years. There were 28 (56%) females and 22 (44%) males in the study group. The nasal bone did not reveal any abnormality in any case. The nasal mucous membrane showed mild chronic inflammatory cell infiltration in 46 (92%) cases and moderate degree in 4 (8%) patients. Chronic inflammation with granulation tissue formation was noted in lacrimal sacs of all patients. The CIS revealed that 14 (28%) cases belonged to "mild" group, 26 (52%) to "moderate" group and 10 (20%) to "severe" category. CONCLUSION: The inclusion of CIS in histomorphological evaluation of DCR specimens is recommended since it is one of the parameters that influence course of the disease.

Analysis of regions within the bacteriophage T4 AsiA protein involved in its binding to the sigma70 subunit of E. coli RNA polymerase and its role as a transcriptional inhibitor and co-activator.

Bacteriophage T4 AsiA, a protein of 90 amino acid residues, binds to the sigma(70) subunit of Escherichia coli RNA polymerase and inhibits host or T4 early transcription or, together with the T4 MotA protein, activates T4 middle transcription. To investigate which regions within AsiA are involved in forming a complex with sigma(70) and in providing transcriptional functions we generated random mutations throughout AsiA and targeted mutations within the C-terminal region. We tested mutant proteins for their ability to complement the growth of T4 asiA am phage under non-suppressing conditions, to inhibit E. coli growth, to interact with sigma(70) region 4 in a two-hybrid assay, to bind to sigma(70) in a native protein gel, and to inhibit or activate transcription in vitro using a T4 middle promoter that is active with RNA polymerase alone, is inhibited by AsiA, and is activated by MotA/AsiA. We find that substitutions within the N-terminal half of AsiA, at amino acid residues V14, L18, and I40, rendered the protein defective for binding to sigma(70). These residues reside at the monomer-monomer interface in recent NMR structures of the AsiA dimer. In contrast, AsiA missing the C-terminal 44 amino acid residues interacted well with sigma(70) region 4 in the two-hybrid assay, and AsiA missing the C-terminal 17 amino acid residues (Delta74-90) bound to sigma(70) and was fully competent in standard in vitro transcription assays. However, the presence of the C-terminal region delayed formation of transcriptionally competent species when the AsiA/polymerase complex was pre-incubated with the promoter in the absence of MotA. Our results suggest that amino acid residues within the N-terminal half of AsiA are involved in forming or maintaining the AsiA/sigma(70) complex. The C-terminal region of AsiA, while not absolutely required for inhibition or co-activation, aids inhibition by slowing the formation of transcription complexes between a promoter and the AsiA/polymerase complex.

Spatially uniform microflows induced by thermoviscous expansion along a traveling temperature wave: analogies with electro-osmotic transport.

We discover that thermoviscous expansion along a traveling wave in a microfluidic channel may be capable of generating a spatially uniform flow profile in a time-averaged sense. We further delineate that the resultant complex flow characteristics, realized by virtue of an intricate interplay between thermal compression-expansion waves and temperature-dependent viscosity variations and controlled by an external heating, may be remarkably characterized by a unique thermal penetration depth scale (analogous to Debye length in electro-osmosis) and a velocity scale (analogous to the Helmholtz Smulochowski velocity in electro-osmosis) that in turn depends on the considerations of "thin" and "thick" microchannel limits, as dictated by the thermal penetration depth as compared to the lateral extent of the microfluidic channel. We show that, when the thermal penetration depth is small as compared to the channel height, a uniform velocity profile is generated in the channel in a time-averaged sense. The velocity scale characterizing this uniform flow may be represented by a function of the thermal diffusivity, volumetric expansion coefficient and thermal viscosity coefficient of the fluid, characteristic amplitude and speed of the thermal wave, as well as the channel height. Results from the present study are expected to provide valuable insights towards arresting hydrodynamic dispersion in microchannels by nonelectrochemical means, following a pH-independent route.

Ribosome-DnaK interactions in relation to protein folding.

Bacterial ribosomes or their 50S subunit can refold many unfolded proteins. The folding activity resides in domain V of 23S RNA of the 50S subunit. Here we show that ribosomes can also refold a denatured chaperone, DnaK, in vitro, and the activity may apply in the folding of nascent DnaK polypeptides in vivo. The chaperone was unusual as the native protein associated with the 50S subunit stably with a 1:1 stoichiometry in vitro. The binding site of the native protein appears to be different from the domain V of 23S RNA, the region with which denatured proteins interact. The DnaK binding influenced the protein folding activity of domain V modestly. Conversely, denatured protein binding to domain V led to dissociation of the native chaperone from the 50S subunit. DnaK thus appears to depend on ribosomes for its own folding, and upon folding, can rebind to ribosome to modulate its general protein folding activity.