Numerical simulations of deformation and aggregation of red blood cells in shear flow.

This article reviews numerical simulations of red blood cells (RBCs) mainly using the lattice Boltzmann method (LBM), focusing on the 2-dimensional deformation and aggregation of the cells in simple shear flow. We outline the incorporation of the immersed boundary method into the LBM, in which the membrane forces are obtained from the membrane model. The RBCs are simulated as a single biconcave capsule and as a doublet of biconcave capsules. The transition from swinging to tumbling motions of the RBCs, as induced by reducing the shear rate or increasing the membrane bending stiffness, is discussed. Also discussed is the aggregation tendency of the doublet of RBCs, for which homogenous deformability maintained RBC aggregation, whereas an increased deformability difference resulted in RBC dissociation.

Effect of different dietary fiber-rich extenders on the quality attributes of functional restructured buffalo meat fillets.

Background: The ever-increasing market of functional meat products demanded especially by modern health conscious consumers has prompted researchers to develop healthier meat products. Aims: This experiment was conducted to improve the dietary fiber-deficient buffalo meat with natural functional fiber-rich extenders. Methods: Meat obtained from the carcass of adult female buffalo (>10 years of age) was procured from the local market within 5-6 h of slaughter, conditioned for 24 h, and then processed by incorporating the dietary fiber-rich extenders at their optimum levels viz. 12% barley flour, 12% maize flour, 10% pea hull powder, and 8% wheat bran (hydrated as 1:1, w/w) for the development of functional restructured buffalo meat fillets (FRBMF). Results: Results revealed higher cooking yield, pH, moisture content, lower protein, and fat percentage for most of the treated samples compared with the control group. The ash percentage of FRBMF prepared with the optimum level of pea hull powder and wheat bran was significantly higher (P<0.05) than in control and other treatments. Shear force values for FRBMF were lower than the control. Total dietary fiber (TDF) percentage of all the treatment products was significantly higher (P<0.05) than the control. Texture profile analysis revealed no significant differences (P>0.05) between FRBMF and the control. The sensory scores for most of the attributes of FRBMF incorporated with the optimum level of extenders were lower but comparable to the control. Conclusion: It was concluded that the functionality of the product had improved, especially in terms of total dietary fiber, as compared to the control. Pea hull powder and wheat bran proved to be excellent sources of dietary fibers, followed by barley and maize flours, respectively.

Comparative efficacy of pour-on eprinomectin and ivermectin against Sarcoptes scabiei in buffaloes.

The efficacy of eprinomectin and ivermectin pour-on was evaluated against Sarcoptes scabiei in naturally infested buffaloes. Eighteen animals were allocated into three groups (A, B and C) of six animals each. Animals in group A were treated with eprinomectin (pour-on) @ 0.5 mg/kg; group B with ivermectin (pour-on) @ 0.2 mg/kg while group C served as untreated controls. Skin scrapings were examined on days 0, 7, 14, 21, 28 and 42 post-treatment (PT). Skin scrapings were found free for mites on day 21 PT, with marked clinical improvement in the lesions after day 28 of treatment. Untreated control group continued to show severe progressive lesions throughout the study period. No clinical side-effects of the tested drugs were observed after treatment. This preliminary report on the efficacy of eprinomectin (pour-on) against S. scabiei in buffaloes is encouraging and results could be of considerable importance.

Human intestinal anion exchanger isoforms: expression, distribution, and membrane localization.

A family of anion exchangers (AEs) including AE1, AE2 and AE3 has been described. AE3 gene has been shown to encode two alternatively spliced isoforms termed as bAE3 (brain subtype) and cAE3 (cardiac subtype). The identity of the AE(s) involved in the human intestinal NaCl absorption is not fully understood. Current studies were undertaken to identify the AE isoforms expressed in the human intestine, to define their regional and vertical axis (crypt vs. surface cells) distribution, and to elucidate their membrane localization in the epithelial cells along the entire length of the human intestine. Our studies utilizing reverse transcription (RT)-PCR with total RNA extracted from pinch biopsies from various regions of the human intestine demonstrate that AE2 and bAE3 but not AE1 or cAE3 were expressed in all the regions of the human intestine. Utilizing in situ RT-PCR, we demonstrated that the message of AE2 was expressed throughout the vertical surface--crypt axis of the colon. Our Western blotting studies demonstrated that AE2 and bAE3 are localized to the basolateral but not the apical membranes of the intestinal epithelial cells from the human ileum and colon. In conclusion, our results demonstrated that in the human intestine, AE2 and bAE3, but not AE1 or cAE3, are expressed throughout the tract with the highest expression in the colon compared to the ileum and jejunum. Both the isoforms were found to be localized to the basolateral but not the apical membranes of the epithelial cells. We speculate that, in the human intestine, AE2 and bAE3 may be the 'housekeeping' isoforms, and the apical AE, the potential candidate for chloride absorption, remains to be identified.

Effects of lateral masking and spatial precueing on gap-resolution in central and peripheral vision.

The data made available by this experiment add two points to the information obtained by previous studies on eccentric vision and lateral masking. First, they demonstrate a clear effect of target-mask similarity on visual gap-resolution in eccentric vision: increasing target-mask similarity systematically decreases resolution performance. Second, spatial precueing has no effect on gap-resolution performance. One implication of this experiment is that with the present stimulus configurations, visual resolution should decrease much more strongly with eccentricity than it does with classical isolated or bar-masked optotypes.

Eye movement control in reading unspaced text: the case of the Japanese script.

The present study examines the landing-site distributions of the eyes during natural reading of Japanese script: a script that mixes three different writing systems (Kanji, Hiragana, and Katakana) and that misses regular spacing between words. The results show a clear preference of the eyes to land at the beginning rather than the center of the word. In addition, it was found that the eyes land on Kanji characters more frequently than on Hiragana or Katakana characters. Further analysis for two- and three-character words indicated that the eye's landing-site distribution differs depending on type of the characters in the word: the eyes prefer to land at the word beginning only when the initial character of the word is a Kanji character. For pure Hiragana words, the proportion of initial fixations did not differ between character positions. Thus, as already indicated by Kambe (National Institute of Japanese Language Report 85 (1986) 29), the visual distinctiveness of the three Japanese scripts plays a role in guiding eye movements in reading Japanese.

Detection of Cl--HCO3- and Na+-H+ exchangers in human airways epithelium.

Molecular species of the Na(+)-H(+) exchanger (NHE) and anion exchanger (AE) gene families and their relative abundance in the human airway regions were assessed utilizing RT-PCR and the RNase protection assay, respectively. Organ donor lung epithelia from various bronchial regions (small, medium, and large bronchi and trachea) were harvested for RNA extraction. Gene-specific primers for the human NHE and AE isoforms were utilized for RT-PCR. Our results demonstrated that NHE1, AE2, and brain AE3 isoforms were expressed in all regions of the human airway, whereas NHE2, NHE3, AE1, and cardiac AE3 were not detected. RNase protection studies for NHE1 and AE2, utilizing glyceraldehyde-3-phosphate dehydrogenase as an internal standard, demonstrated that there were regional differences in the NHE1 mRNA levels in human airways. In contrast, the levels of AE2 mRNA remained unchanged. Differential regional expression of NHE1 isoform may be related to a higher acid load in the tracheal epithelial cells than in epithelia of distal airways. Fluctuations in PCO(2) during inspiration and expiration are probably larger in the tracheal lumen than in the lumen of distal airways with associated larger swings in intracellular pH with each respiratory cycle. Immunohistochemical staining for AE2 protein demonstrated localization to the epithelial cells of human bronchial mucosa.

From "logographic" to normal reading: the case of a deaf beginning reader.

Visual word recognition of a profoundly deaf girl (AH) with developmental reading disorders was explored using an experimental technique that measures performance as a function of eye fixation within a word. AH's fixation-dependent word recognition profile revealed that she was inferring the identity of words using a "logographic" reading strategy (i. e., using salient visual features). Following this observation a special training program that enhances the understanding of grapheme-phoneme relations was applied. After few months of training, AH's reading skills improved, while her fixation-dependent performance changed to become like that of normal readers. We discuss the impact of our technique for the early diagnosis of reading impairments.

Efficacy of eprinomectin pour-on against Rhipicephalus (Boophilus) microplus on buffaloes.

A trial was conducted on 12 buffaloes naturally infested with Rhipicephalus (Boophilus) microplus to evaluate the efficacy of eprinomectin pour-on at a dose of 0.5 mg/kg body weight. A reduction in live tick count by 45.94, 63.96, 81.53, 90.54, 98.19 and 100 % was observed on days 3, 5, 7, 10, 14 and 21 post-treatment, respectively. The reinfestation of ticks was not observed up to 42 days of trial period. On the basis of the present trial of eprinomectin pour-on, it can be recommended for use in dairy buffaloes against Rhipicephalus (Boophilus) microplus infestation.

Role of short chain fatty acids in mesenteric ischemia reperfusion injury in rats.

AIM: The aim of this study was to evaluate the role of short chain fatty acid administration in mesenteric ischemia reperfusion in rats. METHODS: Sixteen 60-day-old male Wistar rats were divided into two groups of eight each. In group I (n=8) normal saline (10 ml/kg) was injected into the ileal lumen. Ischemia reperfusion was achieved by clamping the superior mesenteric artery (SMA) for 30 min and then releasing it for another 30 min. The ileum was harvested for histopathological examination. In group II (n=8) a mixture of short chain fatty acids (10 ml/kg) was injected into the ileal lumen. Ischemia reperfusion was achieved in a similar fashion and the ileum harvested for histopathological examination. Injury was graded according to Chiu's score. RESULTS: The ileum in rats from group II showed a lower injury score (0.013+/-0.354) compared to ileum from rats in group I (4.631+/-0.521), and this difference was significant (p<0.001). CONCLUSION: Short chain fatty acids significantly decreased the degree of reperfusion injury in the gut in a rat model of mesenteric ischemia reperfusion.

Chromogenic in situ hybridization analysis of melastatin mRNA expression in melanomas from American Joint Committee on Cancer stage I and II patients with recurrent melanoma.

OBJECTIVE: To determine whether loss of melastatin (MLSN) is a universal phenomenon in American Joint Committee on Cancer (AJCC) stage I and II melanoma patients who experienced recurrence. MATERIAL AND METHODS: Paraffin blocks of primary melanomas (PMs) were retrieved from 30 patients who had a negative sentinel lymph node biopsy and developed recurrent melanoma (AJCC stage I and II). Chromogenic in situ hybridization (CISH) methods were utilized to evaluate the expression of MLSN mRNA. These results were correlated with clinicopathologic data. RESULTS: Variable, heterogeneous expression of MLSN mRNA was identified in normal, in situ and invasive melanocytes within and between cases. For the invasive PM component, 24 (80%) had focal, regional or complete loss of MLSN mRNA. The remaining 20% had either regional or total partial downregulation of MLSN mRNA. Intact MLSN mRNA expression was present regionally in 14/30 (47%), with mean relative tumor area of 38%, range 5-85%. Increasing loss of MLSN mRNA significantly correlated with increasing tumor depth and microsatellites (r = 0.1/0.4, p = 0.04). However, thin, AJCC T stage 1a PM had higher relative mean loss than intermediate AJCC T stage 2a/2b/3a thickness PM (65% vs. 34%/48%/25%). Increasing loss of MLSN mRNA significantly impacted on disease free survival (DFS) by multivariate analysis (58 vs. 0% 2 years DFS, < or = 75 vs. > 75% mRNA loss, p = 0.02). Decreased overall survival significantly correlated with increasing age and vascular invasion on multivariate analysis. CONCLUSION: Extensive loss of MLSN in PM correlated with aggressive metastatic melanoma. Ancillary testing for MLSN mRNA expression by CISH could offer a means to more accurately identify AJCC stage I and II patients at risk for metastatic disease, who could benefit from adjuvant therapy.

On the role of refixations in letter strings: the influence of oculomotor factors.

Recent studies of reading and word recognition have shown that eye-movement behavior depends strongly on the position in the word that the eye first fixates; the probability of refixating in a word is lowest with the eye near the middle of the word, and it increases as the eye fixates to either side. It has generally been assumed that the cause for this optimal landing position phenomenon lies in the very strong drop-off of visual acuity even within the fovea; refixation should be more likely when the eye starts from a noncentral position, because here less information can be extracted during one fixation. It may, however, be the case that the phenomenon is caused not by acuity drop-off, but by differences in within-word oculomotor scanning tactics as a function of the position that the eye initially fixates. To test this, in the present experiment we kept visual information constant while we varied the initial fixation position. We used homogeneous strings of letters of different length. One letter in each string was different from the rest (e.g., kkkkkok), and this was the letter that the subject initially fixated. This target letter had to be identified before saccading to a comparison string. The position of the target letter in the string was varied from trial to trial. If, owing to acuity limitations, refixations reflect insufficient information extraction, then, because the target letter is always directly fixated, the pattern of refixations in this condition should be independent of the first fixation position. However, the obtained refixation probability showed a strong dependence on the position of first fixation. The number of refixations was independent of the absolute length of the letter strings, but it seemed to be influenced by the proportion of the string over which the eye had to pass. The larger this proportion, the higher the probability of refixation. The results suggest that to a certain extent refixations in letter strings (or words) reflect properties of the oculomotor system rather than visual information extraction.

The effects of target discriminability and retinal eccentricity on saccade latencies: an analysis in terms of variable-criterion theory.

Two experiments are reported that studied changes in saccade latencies (SLs) in a target-identification task as a function of target discriminability and eccentricity. SLs were found to be longer when target discriminability was low and eccentricity was large, both factors showing a significant interaction. Variable-criterion theory (Grice, 1968) was used to derive a working model of the perceptual and decisional processes influencing SLs in the present task. Application of the measurement operations of the theory provided a good quantitative description of individual SL distributions. The analyses in terms of variable-criterion theory suggest that the perceptual process influencing SLs starts earlier and operates at a faster rate when the saccade target can be discriminated on the basis of global-visual features (e.g., size) than when local features (e.g., gaps) have to be extracted.

Anaesthetists' attitudes to monitoring instrument design options.

A survey into the attitudes of anaesthetists to features in monitoring instruments, particularly the design of alarms, visual warnings, alarm limits and the general instrument interface is reported. Questions in the survey had short introductions outlining a clinical scenario followed by items that proposed alternative design features that an instrument might have. Participants were asked to grade their responses to these alternatives on a scale of 1 (strongly disagree) to 5 (strongly agree). The results suggest that anaesthetists would welcome the use of more advanced technology in instrument design. They prefer context-specific messages and alarms. They reject overt control systems for delivering anaesthesia, except for use in exceptional circumstances. Generally, the preferences of anaesthetists are consistent with known principles of safe, ergonomic design.

Developing normal reading skills: aspects of the visual processes underlying word recognition.

Visual word recognition performance of first graders (mean age: 6.6 years) through fifth graders (mean age: 10.8 years) was investigated using an experimental technique that is known to elicit the "viewing position effect" in skilled readers. The results showed that this effect, which consists of a systematic variation of performance as a function of fixation position within words, emerged early at the end of the 1st year of reading instruction. Visual field asymmetries in recognizing individual letters in words were also observed starting from first grade. Effects of word familiarity were obtained as early as in second grade. In contrast to skilled readers, children showed a marked word-length effect, which persisted through the first 5 years of instruction. No other qualitative differences between beginning and skilled readers were apparent. Hence, the basics of reading skills, as measured by the present technique, seem to be attained very early during acquisition. Further experience mainly reduces the time a reader needs to extract visual information from print.

[Interaction effects in the lateral visual field: an extension of Bouma's (1970) approach]. / Interaktionseffekte im seitlichen Gesichtsfeld: Eine Erweiterung des Ansatzes von Bouma (1970).

The recognizability of a letter is impaired by the presence of additional letters. This phenomenon is called lateral masking. Proceeding on the assumption of Bouma (1970) lateral masking can be described in terms of retinal eccentricity of the target letter and the distance between target and flanking stimuli. In this paper, we will address to the question if these kinds of parameters are adequate for describing lateral masking effects. For this purpose, characteristics of the string like its length and its homogenity are varied. The subject's task is to identify the central letter of a tachistoscopically presented string. The targets in the string are flanked both by only x and by different randomly selected letters. Additionally, we varied the length of the string. The data show that these variations influence the strength of the masking effect. It is concluded that a pure sensorical approach is not sufficient for an explanation of lateral masking effects.

Some results on translation invariance in the human visual system.

Four experiments were conducted to study the nature of visual translation invariance in humans. In all the experiments, subjects were trained to discriminate between a previously unknown target and two non-target distractors presented at a fixed retinal location to one side of the fixation point. In a subsequent test phase, this performance was compared with the performance when the patterns were presented either centrally at the fixation point or at a location on the other side of the fixation point, opposite to the location where the patterns were learned, but where acuity was identical to what it was at the learned location. Two different experimental paradigms were used. One used an eye movement control device (Experiment 1) to ensure the eye could not move relative to the patterns to be learned. In the other three experiments, presentation duration of the patterns was restricted to a short enough period to preclude eye movements. During the training period in Experiments 1 and 2, presentation location of the patterns was centered at 2.4 deg in the periphery, whereas in Experiments 3 and 4 presentation eccentricity was reduced to 0.86 and 0.49 deg. In all four experiments performance dropped when the pattern had to be recognized at new test positions. This result suggests that the visual system does not apply a global transposition transformation to the retinal image to compensate for translations. We propose that, instead, it decomposes the image into simple features which themselves are more-or-less translation invariant. If in a given task, patterns can be discriminated using these simple features, then translation invariance will occur. If not, then translation invariance will fail or be incomplete.

Letter visibility and word recognition: the optimal viewing position in printed words.

It has repeatedly been shown that the time and accuracy of recognizing a word depend strongly on where in the word the eye is fixating. Word-recognition performance is maximal when the eye fixates a region near the word's center, and decreases to both sides of this "optimal viewing position." The reason for this phenomenon is assumed to be the strong drop-off of visual acuity: the visibility of letters decreases with increasing eccentricity from fixation location. Consequently, fewer letters can be identified when the beginning or ending of a word is fixated than when its center is fixated. The present study is a test of this visual acuity hypothesis. If the phenomenon is caused by letter visibility, then it should be sensitive to variations of visual conditions in which the letters are presented. By increasing the interletter distances of the word (e.g., a_t_t_e_m_p_t), letter visibility was decreased. As expected from our hypothesis, the viewing-position effect became more exaggerated. An additional experiment showed that destroying word-shape information (e.g., aTtEmPt) decreased overall word-recognition performance but had no influence on the viewing-position effect. Varying the viewing position in words might thus be used as a paradigm, allowing one to separate out the contribution of letter information and supraletter information to word recognition.

Lateral masking: limitations of the feature interaction account.

Recognition performance for a target letter embedded in a string of characters is worse than that for targets presented in isolation. This lateral masking (LM) effect is known to depend on target eccentricity and spacing between target and flankers (Bouma, 1970), indicating that LM arises in early visual processing due to interactions among visual features. The feature interaction account would predict that flankers consisting of similar features produce similar LM effects and that differences in LM produced by different types of flanker diminish with increasing target eccentricity and decreasing spacing. However, in a series of six experiments, this prediction was shown not to be true. Flankers that did not access a higher level code (e.g., pseudoletters or rotated letters) produced more LM than standard letter flankers. Moreover, effects of different flanker types were most pronounced for medium target eccentricities and medium spacings for which recognition performance scores ranged between 40% and 60%.