In silico biophysics and hemorheology of blood hyperviscosity syndrome

Hyperviscosity syndrome (HVS) is characterized by an increase of the blood viscosity by up to seven times the normal blood viscosity, resulting in disturbances to the circulation in the vasculature system. HVS is commonly associated with an increase of large plasma proteins and abnormalities in the properties of red blood cells, such as cell interactions, cell stiffness, and increased hematocrit. Here, we perform a systematic study of the effect of each biophysical factor on the viscosity of blood by employing the dissipative particle dynamic method. Our in silico platform enables manipulation of each parameter in isolation, providing a unique scheme to quantify and accurately investigate the role of each factor in increasing the blood viscosity. To study the effect of these four factors independently, each factor was elevated more than its values for a healthy blood while the other factors remained constant, and viscosity measurement was performed for different hematocrits and flow rates. Although all four factors were found to increase the overall blood viscosity, these increases were highly dependent on the hematocrit and the flow rates imposed. The effect of cell aggregation and cell concentration on blood viscosity were predominantly observed at low shear rates, in contrast to the more magnified role of cell rigidity and plasma viscosity at high shear rates. Additionally, cell-related factors increase the whole blood viscosity at high hematocrits compared with the relative role of plasma-related factors at lower hematocrits. Our results, mapped onto the flow rates and hematocrits along the circulatory system, provide a correlation to underpinning mechanisms for HVS findings in different blood vessels.     

Iterative cooperation between parallel pathways for object and background motion

In a typical visual scene, one or more objects move relative to a larger background, which can itself be in motion as a result of the observer’s eyes moving with respect to the outside world. Here we show that accurate estimation of the background motion from an image velocity field can be accomplished through an iterative cooperation between two modules: one that specializes in calculating a weighted average velocity and another one calculating a velocity contrast map. We build on our analysis to provide a model for the tectum-pretectum loop in the nonmammalian midbrain. Our model accounts for some of the known properties of the tectal neurons (sensitivity to relative motion) and pretectal neurons (sensitivity to whole-field motion). It also agrees with our knowledge of the pretectotectal projection (divergent and inhibitory), and with the results of lesion studies in which the pretectal input to the tectum was removed, leading to hyperactivity of the tectal neurons and the animal. Our model also makes a testable prediction regarding the tectopretectal projection, i.e., that the presence of a larger object and a bigger discrepancy between the directions of motion for the object and the background lead to a larger error by the pretectum in estimating the background motion when the tectal input is abolished.     

Process development for production of human granulocyte-colony stimulating factor by high cell density cultivation of recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis>

The fed-batch process using glucose as the sole source of carbon and energy with exponential feeding rate was carried out for high cell density cultivation of recombinant Escherichia coli BL21 (DE3) expressing human granulocyte-colony stimulating factor (hG-CSF). IPTG was used to induce the expression of hG-CSF at 48 g dry cell wt l⁻¹ during high cell density culture of recombinant E. coli BL21 (DE3) [pET23a-g-csf]. The final cell density, specific yield and overall productivity of hG-CSF were obtained as ~64 g dry cell wt l⁻¹, 223 mg hG-CSF g⁻¹ dry cell wt and 775 mg hG-CSF l⁻¹ h⁻¹, respectively. The resulting purification process used cell lysis, inclusion body (IB) preparation, refolding, DEAE and Butyl-Sepharose. Effects of different process conditions such as cell lysis and washing of IB were evaluated. The results reveal that the cells lyzed at 1,200 bar, 99.9% and Triton removed about 64% of the LPS but sarcosyl had no effect on removal of nucleic acids and LPS. Further analysis show that DEAE column removes DNA about 84%. Cupper concentration was identified as parameter that could have a significant impact on aggregation, as an unacceptable pharmaceutical form that decrease process yields. The purity of purified hG-CSF was more than 99%. Also the comparison of activity between purified hG-CSF and commercial form do not show valuable decrease in activity in purified form.     

Surface topography of kenaf (Hibiscus cannabinus) sized papers

Bleached kenaf handsheets sized with different polymers such as chitosan, polyvinyl alcohol and cationic starch, were used for the determination of surface topography. A non-contact profilometer, the AltiSur 500, was used to characterize the topography of structural details in the paper surface. Numerical and visual characterization of surface roughness indicated that the surface of chitosan-sized paper was less rough than other surfaces, and all the sized papers were commonly smoother than the unsized paper. One property of bio-polymer of chitosan is its ability to form films that improve the surface properties of paper when it is applied to the surface of the sheet.     

Cutaneous melanoma: fishing with chips

DNA microarray technology is a versatile platform that allows rapid genetic analysis to take place on a genome-wide scale and has revolutionized the way cancers are studied. This platform has enabled researchers to characterize mechanisms central to tumorigenesis and understand important molecular events in the multi-step tumor progression model of cutaneous melanoma and other cancers. In melanoma, multiple global gene expression profiling studies using various DNA microarray platforms and various experimental designs have been performed. Each study has been able to capture and characterize either the involvement of a novel pathway or a novel cause-effect-relationship. The use of microarrays to define subclasses, to identify differentially regulated genes within a mutational context to analyze epigenetically regulated genes has resulted in an unprecedented understanding of the biology of cutaneous melanoma that may lead to more accurate diagnosis, more comprehensive prognosis, prediction and more effective therapeutic interventions. Related DNA microarray platforms like array-comparative genomic hybridization (CGH) have also been instrumental to identify many non-random chromosomal alterations; however, studies identifying validated targets as a result of CGH are limited. Thus, there exists significant opportunity to discover novel melanoma genes and translate such discoveries into meaningful clinical endpoints. In this review, we focus on various DNA microarray-based studies performed in cutaneous melanoma and summarize our current understanding of the genetics and biology of melanoma progression derived from accumulating genomic information.     

Enantioselective determination of tramadol and its main phase I metabolites in human plasma by high-performance liquid chromatography

A sensitive and relatively rapid reversed-phase HPLC method was applied to the enantiomeric separation of tramadol and its two main metabolites, O-desmethyltramadol (M1) and N-desmethyltramadol (M2) in plasma samples. Chromatography was performed on an AGP column containing alpha1-acid glycoprotein as chiral selector with a mobile phase of 30 mM diammonium hydrogen phosphate buffer-acetonitrile-triethylamine (98.9:1:0.1, v/v), adjusted to pH 7 by phosphoric acid, and a flow rate of 0.5 ml/min. The fluorescence of analytes was detected at excitation and emission wavelengths of 200 and 301 nm, respectively. The sample preparation was a simple extraction with ethyl acetate using fluconazol as internal standard (IS). The enantiomers of all analytes and IS peaks eluted within 32 min, without any endogenous interference. The calibration curves were linear (r(2) > 0.993) in the concentration range of 2-200, 2.5-100 and 2.5-75 ng/ml for tramadol, M1, and M2 enantiomers, respectively. The within- and between-day variation determined by the measurement of quality control samples at four tested concentrations, showed acceptable values. The lower limit of quantitation was 2 ng/ml for tramadol enantiomers and 2.5 ng/ml for M1 or M2 enantiomers. Mean recoveries of enantiomers from plasma samples were > 81% for all analytes. The procedure was applied to assess the pharmacokinetics of the enantiomers of tramadol and its two main metabolites following oral administration of single 100-mg doses to healthy volunteers.     

Early antibiotic administration but not antibody therapy directed against IL-6 improves survival in septic mice predicted to die on basis of high IL-6 levels

Elevated interleukin (IL)-6 levels correlate with increased mortality following sepsis. IL-6 levels >14,000 pg/ml drawn 6 h after cecal ligation and puncture (CLP) are associated with 100% mortality in ND4 mice, even if antibiotic therapy is initiated 12 h after septic insult. Our first aim was to see whether earlier institution of antibiotic therapy could improve overall survival in septic mice and rescue the subset of animals predicted to die on the basis of high IL-6 levels. Mice (n = 184) were subjected to CLP, had IL-6 levels drawn 6 h later, and then were randomized to receive imipenem, a broad spectrum antimicrobial agent, beginning 6 or 12 h postoperatively. Overall 1-wk survival improved from 25.5 to 35.9% with earlier administration of antibiotics (P < 0.05). In mice with IL-6 levels >14,000 pg/ml, 25% survived if imipenem was started at 6 h, whereas none survived if antibiotics were started later (P < 0.05). On the basis of these results, we examined whether targeted antibody therapy could improve survival in mice with elevated IL-6 levels. A different cohort of mice (n = 54) had blood drawn 6 h after CLP, and then they were randomized to receive either monoclonal anti-IL-6 IgG or irrelevant rat IgG. Anti-IL-6 antibody failed to improve either overall survival or outcome in mice with IL-6 levels >14,000 pg/ml. These results demonstrate that earlier systemic therapy can improve outcome in a subset of mice predicted to die in sepsis, but we are unable to demonstrate any benefit in similar animals using targeted therapy directed at IL-6.     

Functional studies on the ATM intronic splicing processing element

In disease-associated genes, the understanding of the functional significance of deep intronic nucleotide variants may represent a difficult challenge. We have previously reported a new disease-causing mechanism that involves an intronic splicing processing element (ISPE) in ATM, composed of adjacent consensus 5′ and 3′ splice sites. A GTAA deletion within ISPE maintains potential adjacent splice sites, disrupts a non-canonical U1 snRNP interaction and activates an aberrant exon. In this paper, we demonstrate that binding of U1 snRNA through complementarity within a ~40 nt window downstream of the ISPE prevents aberrant splicing. By selective mutagenesis at the adjacent consensus ISPE splice sites, we show that this effect is not due to a resplicing process occurring at the ISPE. Functional comparison of the ATM mouse counterpart and evaluation of the pre-mRNA splicing intermediates derived from affected cell lines and hybrid minigene assays indicate that U1 snRNP binding at the ISPE interferes with the cryptic acceptor site. Activation of this site results in a stringent 5′–3′ order of intron sequence removal around the cryptic exon. Artificial U1 snRNA loading by complementarity to heterologous exonic sequences represents a potential therapeutic method to prevent the usage of an aberrant CFTR cryptic exon. Our results suggest that ISPE-like intronic elements binding U1 snRNPs may regulate correct intron processing.     

Coexistence of atrioventricular nodal reentrant tachycardia and idiopathic left ventricular outflow-tract tachycardia

Double tachycardia is a relatively rare condition. We describe a 21 year old woman with history of frequent palpitations. In one of these episodes, she had wide complex tachycardia with right bundle branch and inferior axis morphology. A typical atrioventricular nodal tachycardia was induced during electrophysiologic study, aimed at induction of clinically documented tachycardia. Initially no ventricular tachycardia was inducible. After successful ablation of slow pathway, a wide complex tachycardia was induced by programmed stimulation from right ventricular outflow tract. Mapping localized the focus of tachycardia in left ventricular outflow tract and successfully ablated via retrograde aortic approach. During 7 month's follow-up, she has been symptom free with no recurrence. This work describes successful ablation of rare combination of typical atrioventricular nodal tachycardia and left ventricular outflow tract tachycardia in the same patient during one session.     

Metabolic and endocrinologic complications in beta-thalassemia major: a multicenter study in Tehran

ABSTRACT : BACKGROUND : The combination of transfusion and chelation therapy has dramatically extended the life expectancy of thalassemic patients. The main objective of this study is to determine the prevalence of prominent thalassemia complications. METHODS : Two hundred twenty patients entered the study. Physicians collected demographic and anthropometric data and the history of therapies as well as menstrual histories. Patients have been examined to determine their pubertal status. Serum levels of 25(OH) D, calcium, phosphate, iPTH were measured. Thyroid function was assessed by T3, T4 and TSH. Zinc and copper in serum were determined by flame atomic absorption spectrophotometry. Bone mineral density (BMD) measurements at lumbar and femoral regions have been done using dual x-ray absorptiometry. The dietary calcium, zinc and copper intakes were estimated by food-frequency questionnaires. RESULTS : Short stature was seen in 39.3% of our patients. Hypogonadism was seen in 22.9% of boys and 12.2% of girls. Hypoparathyroidism and primary hypothyroidism was present in 7.6% and 7.7% of the patients. About 13 % of patients had more than one endocrine complication with mean serum ferritin of 1678 +/- 955 micrograms/lit. Prevalence of lumbar osteoporosis and osteopenia were 50.7% and 39.4%. Femoral osteoporosis and osteopenia were present in 10.8% and 36.9% of the patients. Lumbar BMD abnormalities were associated with duration of chelation therapy. Low serum zinc and copper was observed in 79.6% and 68% of the study population respectively. Serum zinc showed significant association with lumbar but not femoral BMD. In 37.2% of patients serum levels of 25(OH) D below 23 nmol/l were detected. CONCLUSION : High prevalence of complications among our thalassemics signifies the importance of more detailed studies along with therapeutic interventions.