Differential expression and cellular distribution of γ‐tubulin and βIII‐tubulin in medulloblastomas and human medulloblastoma cell lines

The breakdown of the blood–brain barrier (BBB) has been considered to be a key step in the disease process of a number of neurological disorders such as cerebral ischemia and Alzheimer's disease. Many in vitro BBB models derived from animal tissues have been established to elucidate the mechanism of BBB insufficiency. However, only a few human immortalized in vitro BBB models have been reported. In the present study, a temperature‐sensitive SV40‐T antigen was introduced to immortalize cells using a retrovirus to obtain a better human in vitro BBB model which sustains physiological properties. This endothelial cell (EC) line, termed TY08, showed a spindle‐shaped morphology. The cells expressed all key tight junctional proteins, such as occludin, claudin‐5, zonula occludens (ZO)‐1 and ZO‐2 at their cell‐to‐cell boundaries, and had low permeability to inulin across its monolayer. The cells also expressed various influx and efflux transporters and exhibited the functional expression of p‐glycoprotein. Furthermore, the TY08 cells grew and proliferated well under the permissive temperature and stopped growing under the non‐permissive temperature to serve as physiological ECs forming the BBB. Thus, conditionally immortalized TY08 cells retaining the in vivo BBB functions should facilitate analyses for determining the pathophysiology of various neurological diseases. J. Cell. Physiol. 225: 519–528, 2010. © 2010 Wiley‐Liss, Inc.     

Maternal melatonin influences rates of somatic and reproductive organs postnatal development of male rat offspring

Female rat dams, housed in 12L:12D photoperiod, were pinealectomized or injected daily 1(1/2) h before onset of darkness with 250 mg melatonin/100 g BW., during pregnancy; control and pinealectomized dams received a placebo. Somatic, reproductive organs and gonadotropins levels luteinizing hormone (LH) and follicle stimulating hormone (FSH) of male offspring were examined at the following phases of their sexual development: neonate, infantile, juvenile or prepubertal and pubertal periods. Pinealectomy of the mother produced an altered developmental pattern in the offspring (PIN-X offspring). During the infantile period when pups are lacking maternal melatonin and their own melatonin rhythm is not yet established, a delayed growth of body and testis weights was observed. After the second week of life, from 15 to 25 days of age, coinciding with the initiation of the melatonin rhythm, a speed-up growth of body and testes was observed, followed by a delayed growth from 25 to 30 days, in the juvenile period; this also coinciding with reduced LH levels observed at 30 days of age. Indeed, in PIN-X offspring significantly greater growth rate was observed during the pubertal period than in control offspring, which could be due to the increase in LH secretion up to normal values observed in the PIN-X offspring. Seminal vesicles of the PIN-X offspring also showed delayed growth, which was overcome at the pubertal period. Melatonin (MEL) treatment during pregnancy produced minor alterations in postnatal development of the reproductive tract. Only increased pituitary gland weight was observed at 15 and decreased at 25 days of age. At 25 days of age, MEL offspring reached the highest LH values, and at 30 days of age, PIN-X offspring still show low values. Which suggests that other factors than the endocrine activity of the gland are affecting the somatic growth of the pituitary gland. Seminal vesicles weight was delayed at 25 days of age in the MEL offspring. These results indicate that maternal melatonin is necessary for a normal somatic growth and postnatal development of reproductive organs of the offspring.     

Cytologic features of solitary fibrous tumor of the parotid gland. A case report

BACKGROUND: Solitary fibrous tumor (SFT) is a rare neoplasm that most commonly involves the pleura but is increasingly recognized at other locations, including lung, liver, thyroid and parotid glands, with only a few reports describing its cytologic features. CASE: The fine needle aspiration biopsy (FNAB) features of an SFT located in the left parotid gland of a 34-year-old woman were compared to the histologic and immunohistochemical aspects of the lesion. CONCLUSION: This case confirms that SFT has distinct cytomorphologic features and that FNAB can be helpful in its diagnosis.     

The Wzz (Cld) Protein in Escherichia coli: Amino Acid Sequence Variation Determines O-Antigen Chain Length Specificity

The O antigen is a polymer with a repeated unit. The chain length in most Escherichia coli strains has a modal value of 10 to 18 O units, but other strains have higher or lower modal values. wzz (cld/rol) mutants have a random chain length distribution, showing that the modal distribution is determined by the Wzz protein. Cloned wzz genes from E. coli strains with short (7 to 16), intermediate (10 to 18), and long (16 to 25) modal chain lengths were transferred to a model system, and their effects on O111 antigen were studied. The O111 chain length closely resembled that of the parent strains. We present data based on the construction of chimeric wzz genes and site-directed mutagenesis of the wzz gene to show that the modal value of O-antigen chain length of E. coli O1, O2, O7, and O157 strains can be changed by specific amino acid substitutions in wzz. It is concluded that the O-antigen chain length heterogeneity in E. coli strains is the result of amino acid sequence variation of the Wzz protein.     

High-throughput film-densitometry: an efficient approach to generate large data sets

A film-handling machine (robot) has been built which can, in conjunction with a commercially available film densitometer, exchange and digitize over 300 electron micrographs per day. Implementation of robotic film handling effectively eliminates the delay and tedium associated with digitizing images when data are initially recorded on photographic film. The modulation transfer function (MTF) of the commercially available densitometer is significantly worse than that of a high-end, scientific microdensitometer. Nevertheless, its signal-to-noise ratio (S/N) is quite excellent, allowing substantial restoration of the output to "near-to-perfect" performance. Due to the large area of the standard electron microscope film that can be digitized by the commercial densitometer (up to 10,000 x 13,680 pixels with an appropriately coded holder), automated film digitization offers a fast and inexpensive alternative to high-end CCD cameras as a means of acquiring large amounts of image data in electron microscopy.     

Relationships between quantitative and reproductive fitness traits in animals

The relationships between quantitative and reproductive fitness traits in animals are of general biological importance for the development of population genetic models and our understanding of evolution, and of great direct economical importance in the breeding of farm animals. Two well investigated quantitative traits--body weight (BW) and litter size (LS)--were chosen as the focus of our review. The genetic relationships between them are reviewed in fishes and several mammalian species. We have focused especially on mice where data are most abundant. In mice, many individual genes influencing these traits have been identified, and numerous quantitative trait loci (QTL) located. The extensive data on both unselected and selected mouse populations, with some characterized for more than 100 generations, allow a thorough investigation of the dynamics of this relationship during the process of selection. Although there is a substantial positive genetic correlation between both traits in unselected populations, caused mainly by the high correlation between BW and ovulation rate, that correlation apparently declines during selection and therefore does not restrict a relatively independent development of both traits. The importance of these findings for overall reproductive fitness and its change during selection is discussed.     

Thrombomodulin changes the molecular surface of interaction and the rate of complex formation between thrombin and protein C

The interaction of thrombin with protein C triggers a key down-regulatory process of the coagulation cascade. Using a panel of 77 Ala mutants, we have mapped the epitope of thrombin recognizing protein C in the absence or presence of the cofactor thrombomodulin. Residues around the Na(+) site (Thr-172, Lys-224, Tyr-225, and Gly-226), the aryl binding site (Tyr-60a), the primary specificity pocket (Asp-189), and the oxyanion hole (Gly-193) hold most of the favorable contributions to protein C recognition by thrombin, whereas a patch of residues in the 30-loop (Arg-35 and Pro-37) and 60-loop (Phe-60h) regions produces unfavorable contributions to binding. The shape of the epitope changes drastically in the presence of thrombomodulin. The unfavorable contributions to binding disappear and the number of residues promoting the thrombin-protein C interaction is reduced to Tyr-60a and Asp-189. Kinetic studies of protein C activation as a function of temperature reveal that thrombomodulin increases >1,000-fold the rate of diffusion of protein C into the thrombin active site and lowers the activation barrier for this process by 4 kcal/mol. We propose that the mechanism of thrombomodulin action is to kinetically facilitate the productive encounter of thrombin and protein C and to allosterically change the conformation of the activation peptide of protein C for optimal presentation to the thrombin active site.     

Helminth infracommunity structure of the sympatric garter snakes Thamnophis eques and Thamnophis melanogaster from the Mesa Central of Mexico

Seventy-two Mexican garter snakes (Thamnophis eques) and 126 black-bellied garter snakes (T. melanogaster) were collected from 4 localities of the Mesa Central of Mexico between July 1996 and February 1998 and examined for helminths. Both species of garter snakes occurred sympatrically in every locality except in Lake Cuitzeo. Both species of snakes shared 9 helminth species, and in general, T. melanogaster hosted a larger number of species than T. eques. In each locality, a different helminth species showed the highest levels of prevalence and abundance (Spiroxys susanae in Ciénaga de Lerma, Telorchis corti in Lago de Pátzcuaro, Proteocephalus variabilis in Lago de Cuitzeo, and Contracaecum sp. in Lago de Chapala). Helminth communities in garter snakes of the Mesa Central are depauperate and dominated by a single parasite species. In those localities where the snakes occurred in sympatry, helminth communities were, in general, more diverse and species-rich in T. melanogaster. Differences in the ecology and physiology of these species of garter snakes may explain this pattern because black-bellied garter snakes (T. melanogaster) are more aquatic than Mexican garter snakes (T. eques) and primarily eat aquatic prey, potentially exposing themselves to a larger number of helminths transmitted by predator-prey infection. The helminth infracommunities of garter snakes in the Mesa Central of Mexico show a strong Nearctic influence because most of the species infecting these hosts have been recorded in other Nearctic colubrid snakes. However, the helminth infracommunities of these garter snakes are less species-rich and less diverse than those in colubrid snakes in more temperate latitudes. The widespread ecological perturbation of sampling sites in the Mesa Central because of human activity, and geographic differences in foraging ecology of the hosts and, thus, exposure to parasites transmitted by intermediate hosts may help to explain these patterns.     

Rural-Urban Differences in Household Treatment-Seeking Behaviour for Suspected Malaria in Children at Bata District,Equatorial Guinea

BackgroundMalaria remains a major cause of morbidity and mortality among children under five years old in Equatorial Guinea. However, little is known about the community management of malaria and treatment-seeking patterns. We aimed to assess symptoms of children with reported malaria and treatment-seeking behaviour of their caretakers in rural and urban areas in the Bata District.MethodologyA cross-sectional study was conducted in the district of Bata and 440 houses were selected from 18 rural villages and 26 urban neighbourhoods. Differences between rural and urban caregivers and children with reported malaria were assessed through the chi-squared test for independence of categorical variables and the t-Student or the non-parametric Mann-Whitney test for normally or not-normally distributed continuous variables, respectively.ResultsDifferences between rural and urban households were observed in caregiver treatment-seeking patterns. Fever was the main symptom associated with malaria in both areas. Malaria was treated first at home, particularly in rural areas. The second step was to seek treatment outside the home, mainly at hospital and Health Centre for rural households and at hospital and private clinic for urban ones. Artemether monotherapy was the antimalarial treatment prescribed most often. Households waited for more than 24 hours before seeking treatment outside and delays were longest in rural areas. The total cost of treatment was higher in urban than in rural areas in Bata.ConclusionsThe delays in seeking treatment, the type of malaria therapy received and the cost of treatment are the principal problems found in Bata District. Important steps for reducing malaria morbidity and mortality in this area are to provide sufficient supplies of effective antimalarial drugs and to improve malaria treatment skills in households and in both public and private sectors.