Optimising adjacent membrane segmentation and parameterisation in multicellular aggregates by piecewise active contours.

In fluorescence microscopy imaging, the segmentation of adjacent cell membranes within cell aggregates, multicellular samples, tissue, organs, or whole organisms remains a challenging task. The lipid bilayer is a very thin membrane when compared to the wavelength of photons in the visual spectra. Fluorescent molecules or proteins used for labelling membranes provide a limited signal intensity, and light scattering in combination with sample dynamics during in vivo imaging lead to poor or ambivalent signal patterns that hinder precise localisation of the membrane sheets. In the proximity of cells, membranes approach and distance each other. Here, the presence of membrane protrusions such as blebs; filopodia and lamellipodia; microvilli; or membrane vesicle trafficking, lead to a plurality of signal patterns, and the accurate localisation of two adjacent membranes becomes difficult. Several computational methods for membrane segmentation have been introduced. However, few of them specifically consider the accurate detection of adjacent membranes. In this article we present ALPACA (ALgorithm for Piecewise Adjacent Contour Adjustment), a novel method based on 2D piecewise parametric active contours that allows: (i) a definition of proximity for adjacent contours, (ii) a precise detection of adjacent, nonadjacent, and overlapping contour sections, (iii) the definition of a polyline for an optimised shared contour within adjacent sections and (iv) a solution for connecting adjacent and nonadjacent sections under the constraint of preserving the inherent cell morphology. We show that ALPACA leads to a precise quantification of adjacent and nonadjacent membrane zones in regular hexagons and live image sequences of cells of the parapineal organ during zebrafish embryo development. The algorithm detects and corrects adjacent, nonadjacent, and overlapping contour sections within a selected adjacency distance d, calculates shared contour sections for neighbouring cells with minimum alterations of the contour characteristics, and presents piecewise active contour solutions, preserving the contour shape and the overall cell morphology. ALPACA quantifies adjacent contours and can improve the meshing of 3D surfaces, the determination of forces, or tracking of contours in combination with previously published algorithms. We discuss pitfalls, strengths, and limits of our approach, and present a guideline to take the best decision for varying experimental conditions for in vivo microscopy.

Actualización sobre hiperglucemia posprandial: fisiopatología, prevalencia, consecuencias e implicaciones para el tratamiento de la diabetes / Update on postprandial hyperglycaemia: the pathophysiology, prevalence, consequences and implications of treating diabetes

Para alcanzar un control glucémico adecuado, la hiperglucemia posprandial y basal debe reducirse. Diversos estudios epidemiológicos sugieren una asociación de las fluctuaciones de glucemia posprandial con el riesgo cardiovascular. Sin embargo, los estudios de intervención realizados hasta el momento no demuestran que el control selectivo de la hiperglucemia posprandial se asocie con beneficios cardiovasculares. En consecuencia, una adecuada combinación de fármacos, que controlen tanto la hiperglucemia basal como la posprandial, de forma individualizada según las características de cada paciente, es la mejor estrategia para alcanzar un buen control glucémico. Esta revisión pretende acercar a los clínicos el concepto de hiperglucemia posprandial, analizando las causas, cómo puede medirse, su prevalencia, sus consecuencias y, finalmente, qué estrategias terapéuticas existen para el control preferente de la misma junto a la hiperglucemia basal

To achieve appropriate glycaemic control, postprandial and baseline hyperglycaemia should be reduced. Various epidemiological studies have suggested an association between fluctuations in postprandial blood glucose and cardiovascular risk. However, studies of interventions performed to date have not shown that selective control of postprandial hyperglycaemia is associated with cardiovascular benefits. Accordingly, an appropriate combination of drugs that control both baseline and postprandial hyperglycaemia (individually based on each patient's characteristics) is the best strategy for achieving good glycaemic control. This review seeks to impart to clinicians the concept of postprandial hyperglycaemia, analysing its causes, how to measure it, its prevalence, its consequences and, ultimately, the available therapeutic strategies for the preferential control of the postprandial hyperglycaemia along with baseline hyperglycaemia

Update on postprandial hyperglycaemia: the pathophysiology, prevalence, consequences and implications of treating diabetes. / Actualización sobre hiperglucemia posprandial: fisiopatología, prevalencia, consecuencias e implicaciones para el tratamiento de la diabetes.

To achieve appropriate glycaemic control, postprandial and baseline hyperglycaemia should be reduced. Various epidemiological studies have suggested an association between fluctuations in postprandial blood glucose and cardiovascular risk. However, studies of interventions performed to date have not shown that selective control of postprandial hyperglycaemia is associated with cardiovascular benefits. Accordingly, an appropriate combination of drugs that control both baseline and postprandial hyperglycaemia (individually based on each patient's characteristics) is the best strategy for achieving good glycaemic control. This review seeks to impart to clinicians the concept of postprandial hyperglycaemia, analysing its causes, how to measure it, its prevalence, its consequences and, ultimately, the available therapeutic strategies for the preferential control of the postprandial hyperglycaemia along with baseline hyperglycaemia.

Unravelling Receptor and RGD Motif Dependence of Retargeted Adenoviral Vectors using Advanced Tumor Model Systems.

Recent advances in engineering adenoviruses are paving the way for new therapeutic gene delivery approaches in cancer. However, there is limited knowledge regarding the impact of adenoviral retargeting on transduction efficiency in more complex tumor architectures, and the role of the RGD loop at the penton base in retargeting is unclear. To address this gap, we used tumor models of increasing complexity to study the role of the receptor and the RGD motif. Employing tumor-fibroblast co-culture models, we demonstrate the importance of the RGD motif for efficient transduction in 2D through the epithelial cell adhesion molecule (EpCAM), but not the epidermal growth factor receptor (EGFR). Via optical clearing of co-culture spheroids, we show that the RGD motif is required for transduction via both receptors in 3D tumor architectures. We subsequently employed a custom-designed microfluidic model containing collagen-embedded tumor spheroids, mimicking the interplay between interstitial flow, extracellular matrix and adenoviral transduction. Image analysis of on-chip cleared spheroids indicated the importance of the RGD motif for on-chip adenoviral transduction. Together, our results show the interrelationship between receptor characteristics, the RGD motif, the 3D tumor architecture and retargeted adenoviral transduction efficiency. The findings are important for the rational design of next-generation therapeutic adenoviruses.

Experimento de Harvey: caso clínico, diagnóstico y cirugía vascular / Harvey's experiment: clinical case, diagnosis and vascular surgery

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Aristóteles y Harvey: antecesores de la angiología y la cirugía vascular / Aristotle and Harvey: predecessors of angiology and vascular surgery

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Computational methods for analysis of dynamic events in cell migration.

Cell migration is a complex biological process that involves changes in shape and organization at the sub-cellular, cellular, and supra-cellular levels. Individual and collective cell migration can be assessed in vitro and in vivo starting from the flagellar driven movement of single sperm cells or bacteria, bacterial gliding and swarming, and amoeboid movement to the orchestrated movement of collective cell migration. One key technology to access migration phenomena is the combination of optical microscopy with image processing algorithms. This approach resolves simple motion estimation (e.g. preferred direction of migrating cells or path characteristics), but can also reveal more complex descriptors (e.g. protrusions or cellular deformations). In order to ensure an accurate quantification, the phenomena under study, their complexity, and the required level of description need to be addressed by an adequate experimental setup and processing pipeline. Here, we review typical workflows for processing starting with image acquisition, restoration (noise and artifact removal, signal enhancement), registration, analysis (object detection, segmentation and characterization) and interpretation (high level understanding). Image processing approaches for quantitative description of cell migration in 2- and 3-dimensional image series, including registration, segmentation, shape and topology description, tracking and motion fields are presented. We discuss advantages, limitations and suitability for different approaches and levels of description.

[Renal compromise in HIV/AIDS in patients attended at a Chilean children hospital]. / Compromiso renal e infección por VIH/SIDA en pacientes atendidos en un hospital pediátrico chileno.

UNLABELLED: The aim of this study was to determine the frequency of renal abnormalities in HIV positive children hospitalized in one pediatric hospital in Chile. METHOD: a cross sectional study was performed during April 2007. RESULTS: A total of 18 patients were evaluated, ten male and eight female ranging in age from 4 to 19 years. The average age at the time of HIV diagnosis and nephrologic evaluations were 2,69 and 10,7 years respectively. All patients had acquired HIV infection by vertical transmission. Uriñe samples of two children had microalbuminuria; two had monosymptomatic hematuria, and ten had ¿squamous? cells. Hypercalciuria was detected in one patient, renal lithiasis in another and two patients had abnormal renal ultrasonography. All 19 patients had normal blood pressures. Overall 7 patients (39%) had a renal abnormality. CONCLUSIONS: The relatively high incidence of renal abnormalities in our series support the need for a nation-wide screening program to assess the incidence of renal impairment in pediatric HIV positive patients.

Compromiso renal e infección por VIH/SIDA en pacientes atendidos en un hospital pediátrico chileno / Renal compromise in HIV/AIDS in patients attended at a Chilean children hospital

The aim of this study was to determine the frequency of renal abnormalities in HIV positive children hospitalized in one pediatric hospital in Chile. Method: a cross sectional study was performed during April 2007. Results: A total of 18 patients were evaluated, ten male and eight female ranging in age from 4 to 19 years. The average age at the time of HIV diagnosis and nephrologic evaluations were 2,69 and 10,7 years respectively. All patients had acquired HIV infection by vertical transmission. Uriñe samples of two children had microalbuminuria; two had monosymptomatic hematuria, and ten had ¿squamous? cells. Hypercalciuria was detected in one patient, renal lithiasis in another and two patients had abnormal renal ultrasonography. All 19 patients had normal blood pressures. Overall 7 patients (39 percent) had a renal abnormality. Conclusions: The relatively high incidence of renal abnormalities in our series support the need for a nation-wide screening program to assess the incidence of renal impairment in pediatric HIV positive patients.

El objetivo de este estudio fue evaluar la función renal de pacientes infectados con virus de inmuno-deficiencia humana (VIH) que se controlan en un hospital pediátrico chileno. Método: estudio de corte transversal. Resultados: Se evaluaron 18 pacientes, 10 varones y 8 mujeres; edad: entre 4 y 19 años, la edad promedio al diagnóstico de la infección por VIH y al momento de la evaluación fue 2,69 y 10,7 años, respectivamente. Todos nuestros pacientes adquirieron la infección vía vertical. Dos presentaron microalbuminuria y dos hematuria monosintomática. En 10 (55 por ciento) se encontraron células descamativas, en uno hiper-calciuria y en otro litiasis renal. Todos tuvieron presión arterial normal. La ecotomograña renal fue anormal en dos. Se han descrito varias anormalidades renales en pacientes con infección por VIH; en nuestro estudio, 7 pacientes (39 por ciento) tuvieron alteraciones en los exámenes de laboratorio. Conclusión: La alta frecuencia de afectación renal encontrada en pacientes pediátricos con infección por VIH hace necesario plantear un tamizaje nacional para determinar la incidencia de nefropatía asociada en nuestros pacientes.

Altered beta-amyloid precursor protein isoforms in Mexican Alzheimer's Disease patients.

OBJECTIVE: To determine the beta-amyloid precursor protein (betaAPP) isoforms ratio as a risk factor for Alzheimer's Disease and to assess its relationship with demographic and genetic variables of the disease. METHODS: Blood samples from 26 patients fulfilling NINCDS-ADRDA diagnostic criteria for AD and 46 healthy control subjects were collected for Western blotting for betaAPP. A ratio of betaAPP isoforms, in optical densities, between the upper band (130 Kd) and the lower bands (106-110 Kd) was obtained. Odds ratios were obtained to determine risk factor of this component. RESULTS: betaAPP ratio on AD subjects was lower than that of control subjects: 0.3662 +/- 0.1891 vs. 0.6769 +/- 0.1021 (mean +/- SD, p<0.05). A low betaAPP ratio (<0.6) showed an OR of 4.63 (95% CI 1.45-15.33). When onset of disease was taken into account, a betaAPP ratio on EOAD subjects of 0.3965 +/- 0.1916 was found vs. 0.3445 +/- 0.1965 on LOAD subjects (p>0.05). CONCLUSIONS: Altered betaAPP isoforms is a high risk factor for Alzheimer's disease, although it has no influence on the time of onset of the disease.

Comparative sequence analysis of spa gene of Staphylococcus aureus isolated from bovine mastitis: characterization of an unusual spa gene variant.

The protein A encoding gene spa of four Staphylococcus aureus strains isolated from bovine clinical mastitis was amplified by PCR and sequenced. The four strains were selected after an initial screening of spa gene of 41 strains isolated from mastitic cows and were subjected to detailed investigations. According to the sequencing results the spa gene of three strains (M1, M2, M3) appeared with gene segments encoding five (E, D, A, B and C) and four (E, A, B and C) IgG binding domains for two (M1, M3) and one (M2) strain, respectively and with gene segments encoding four, two and two repeats of the octapeptide Xr-repeats for the strains M1, M2 and M3, respectively. For the remaining Staph. aureus strain (M4) gene segments encoding IgG binding domains E, D and A and a new domain BC with a size of 219 bp could be observed. The BC domain appears, with a deletion of a 123 bp segment from the border region between both domains, as fused domain of both previously characterized domains. The Xr-region of this strain had 11 octapeptide repeats.

Presence of human papilloma virus in tumor tissue from children with retinoblastoma: an alternative mechanism for tumor development.

Epidemiological studies have shown that the use of barrier methods of contraception is associated with a decreased incidence of papilloma virus infection and reduced risk of having a child with retinoblastoma. Thirty-nine primary retinoblastomas were analyzed for the presence of papilloma virus sequences. Tumor tissue sections were also used to assess the expression of the retinoblastoma protein and proliferative index. Papilloma sequences were detected in 14 of 39 (36%) tumors. Tumors in which viral sequences were detected were associated with a lower proliferative index (68% versus 78%; P = 0.015). Children with tumors containing viral sequences had a lower risk of extraocular disease (odds ratio, 9.0; 95% confidence interval, 1.6-49; P = 0.008) and a lower birth weight (2.9 versus 3.5 kg; P = 0.030). Based on these data, it is our hypothesis that papilloma viruses may play a role in the development of sporadic retinoblastoma. Detection of papilloma virus sequences and retinoblastoma protein in certain primary lesions suggests an alternative mechanism of tumor development for sporadic retinoblastoma.

Relación entre tacto rectal, antígeno prostático específico y estudio anatomopatológico para el diagnóstico de tumores prostáticos / Correlation between digital rectal examination, prostate specific antigen and anatomopathological studies for the diagnosis of pancreatic tumor

Para establecer el diagnóstico de tumores de próstata, se deben aplicar tres criterios: epidemiológico, clínico y de laboratorio. Aquí fueron evaluados los dos últimos en hiperplasia* benigna (HBP) y cáncer de próstata (Ca. prostático). Se midió la exactitud del tacto rectal (TR) y del antígeno prostático específico (APE) cmo pruebas para la detección de tumores prostáticos en pacientes del Hospital General de Enfermedades del Instituto Guatemalteco de Seguridad Social (IGSS). Fueron recopilados los datos de 251 pacientes, a quienes se les realizó TR, APE y estudio anatomopatológico durante el 1-1-1994 al 31-12-1997. Los resulados mostraron que el TR es superior al APE como método diagnóstico único para detección de HBP, mientras que para detección de Ca. prostático, el APE fue superior al TR. La importancia del APE radica en la detección precoz del cáncer donde la cirugía ofrece posibilidades de control. La mayor precisión se obtuvo al combinar el TR con el APE. Por lo tanto se recomienda su aplicación combinada para pacientes con sospecha de un tumor prostático, y para tamizar población en riesgo

Cloning, sequencing and expression in MEL cells of a cDNA encoding the mouse ribosomal protein S5.

We describe the isolation and characterization of a cDNA encoding the mouse S5 ribosomal protein. It was isolated from a MEL (murine erythroleukemia) cell cDNA library by differential hybridization as a down regulated sequence during HMBA-induced differentiation. Northern series analysis showed that S5 mRNA expression is reduced 5-fold throughout the differentiation process. The mouse S5 mRNA is 760 bp long and encodes for a 204 amino acid protein with 94% homology with the human and rat S5.

H3.3A variant histone mRNA containing an alpha-globin insertion: modulated expression during mouse gametogenesis correlates with meiotic onset.

Replacement-variant H3.3 histones have been isolated and sequenced in different eukaryotes, but no functional H3.3A gene has been characterized in the mouse so far. We have cloned an H3.3A cDNA from a mouse fetal ovary library, differentially screened with testis versus somatic cDNA probes. We showed this gene contains a region homologous to the reverse and complementary alpha-globin gene. We believe such a structure could have been generated by retroposition during the evolution of both globin and histone gene families. The sequence coding for H3.3A is 76.6% homologous to the mouse H3.3B gene at the nucleotide level and differs in only one amino acid at the protein level. The high degree of homology between these genes and the H3.3 variant histones from other eukaryotes reveals the conservation of these replication-independent class of histones throughout evolution. Analysis of gene expression reveals a developmental regulation concurrent with meiotic progression, with the highest level of transcript detection coincident with meiotic onset during both oogenesis and spermatogenesis.

Congenital hypertrichosis, osteochondrodysplasia, and cardiomegaly: further delineation of a new genetic syndrome.

The hypertrichosis and osteochondrodysplasia syndrome is a rare entity with clinical findings including macrosomia at birth cardiomegaly. Autosomal recessive inheritance is presumed based on the report of two affected sibs born to healthy parents. Here we report on four new patients with their follow-up data, as well as on one of the four cases from the original report. Comparison of all eight cases indicates that they share 50% of clinical and radiological changes. This report contributes to the further delineation of this newly recognized syndrome.

Developmental expression of H3.3A variant histone mRNA in mouse.

Cloning and characterization of H3.3A variant histone expression has recently been reported to be associated with meiotic development in mouse testis and ovary. Using Northern analysis and in situ hybridization, the pattern of H3.3A expression was studied during the development of different tissues. In addition to the differential expression detected in male and female meiosis, H3.3A was found to be highly expressed in preantral follicles of adult ovaries and in the basal regions of seminiferous epithelium corresponding to spermatogonia. Different patterns of expression were observed in somatic tissues, which also differed with respect to the developmental stage of the tissue. The lowest expression was detected in adult skeletal muscle. High expressions were found in foetal liver and spinal cord. These different expressions might reflect a possible function of H3.3A in cell differentiation as detected in MEL cells.

Genetic evidence in melanoma and bladder cancers that p16 and p53 function in separate pathways of tumor suppression.

The 9p21 region of human chromosome 9 is a hot spot for chromosomal aberrations in both cultured cell lines and primary tumors. This region contains a gene, P16 (also called MTS1, CDKN2 and p16INK4), that encodes a presumptive negative cell cycle regulator called p16. P16 is deleted or mutated at high frequency in a variety of tumor cell lines including melanoma and bladder carcinoma lines. As such, it is likely to be a tumor suppressor gene. Here we show that P16 is mutated in primary bladder carcinomas (3 of 33) and melanomas (5 of 34). These findings support studies that show P16 mutations are not solely a product of growth in tissue culture but rather are involved in formation of tumors in viva. Some bladder primary tumors and some bladder and melanoma tumor cell lines contain mutations in both P16 and P53 at frequencies that suggest that p53 and p16 function in different pathways, each of which is important in suppressing malignant transformation.

Inhibition of posterior capsule opacification: the effect of colchicine in a sustained drug delivery system.

We investigated the effect of colchicine in a sustained drug delivery system on posterior capsule opacification (PCO) in rabbit eyes. A polymer matrix wafer, which diffused colchicine at a steady rate, was implanted in the capsular bag of 34 eyes after the lens material was removed by endocapsular phacoemulsification. Three different drug concentrations were used in the rabbit eyes, which were compared with control eyes containing the polymer matrix wafer without colchicine. The mean PCO score was highest in the control group without colchicine and increased steadily over 12 weeks. The rate of PCO formation in all eyes treated with colchicine was significantly lower than in the control group. There was no statistically significant improvement in PCO inhibition with the higher colchicine dosages. Side effects included inflammatory anterior chamber reaction and corneal and retinal complications and were most notable with the highest drug concentration. Slow release of colchicine reduces PCO formation in the rabbit. The optimal biocompatible dosage must be carefully determined and warrants further investigation.

Clinicopathologic study of the effect of radial tears and loop fixation on intraocular lens decentration.

PURPOSE: The purpose of this study is to determine the effect of loop fixation and anterior capsular tears on intraocular lens (IOL) decentration. METHODS: A retrospective measurement of IOL decentration was performed on 144 human eyes with posterior chamber (PC) IOLs obtained after death. RESULTS: Decentration in eyes with asymmetrical bag-sulcus fixation (mean +/- standard deviation, 0.64 +/- 0.39 mm) was significantly higher than eyes with symmetrical fixation. In the presence of radial tears, symmetrically fixated IOLs in either the capsular bag or the ciliary sulcus decentered to a similar degree, 0.35 +/- 0.25 mm and 0.4 +/- 0.26 mm, respectively. The least decentration was observed with capsular fixation and no radial tears (0.18 +/- 0.09 mm). This was significantly less decentration than with any other form of fixation in the presence of radial tears. CONCLUSION: This study shows that capsular fixation with no radial tears, as can be achieved by using the continuous curvilinear capsulorhexis, is associated with the least decentration.