Association between carotid plaque characteristics and cerebral white matter lesions: one-year follow-up study by MRI

Objective

To prospectively assess the relation between carotid plaque characteristics and the development of new cerebral white matter lesions (WMLs) at MRI.

Methods

Fifty TIA/stroke patients with ipsilateral 30–69% carotid stenosis underwent MRI of the plaque at baseline. Total plaque volume and markers of vulnerability to thromboembolism (lipid-rich necrotic core [LRNC] volume, fibrous cap [FC] status, and presence of intraplaque hemorrhage [IPH]) were assessed. All patients also underwent brain MRI at baseline and after one year. Ipsilateral cerebral WMLs were quantified with a semiautomatic method.

Results

Mean WML volume significantly increased over a one-year period (6.52 vs. 6.97 mm³, P = 0.005). WML volume at baseline and WML progression did not significantly differ (P>0.05) between patients with 30–49% and patients with 50–69% stenosis. There was a significant correlation between total plaque volume and baseline ipsilateral WML volume (Spearman ρ = 0.393, P = 0.005). There was no significant correlation between total plaque volume and ipsilateral WML progression. There were no significant associations between LRNC volume and WML volume at baseline and WML progression. WML volume at baseline and WML progression did not significantly differ between patients with a thick and intact FC and patients with a thin and/or ruptured FC. WML volume at baseline and WML progression also did not significantly differ between patients with and without IPH.

Conclusion

The results of this study indicate that carotid plaque burden is significantly associated with WML severity, but that there is no causal relationship between carotid plaque vulnerability and the occurrence of WMLs.     

Chorioallantoic and yolk sac placentation in Thrichomys laurentinus (Echimyidae) and the evolution of hystricognath rodents

The evolutionary history of Hystricognathi is associated with major transformations in their placental system. Data so far indicate that key characters are independent from size dimensions in medium to very large species. To better understand the situation in smaller species, we analyzed placental development in a spiny rat, Thrichomys laurentinus. Fourteen individuals ranging from early implantation to near term were investigated by histology, immunohistochemistry, proliferation activity and electron microscopy. Placentation in Thrichomys revealed major parallels to the guinea pig and other hystricognath rodents with respect to the early and invasive implantation, the process of trophoblast invasion, the internal organization of the labyrinth and the trophospongium as well as the establishment of the complete inverted yolk sac placenta. In contrast to systematically related small-sized species, the placental regionalization in Thrichomys was characterized by a remarkable lobulated structure and associated growing processes. Reverse to former perspectives, these conditions represented ancient character states of hystricognaths. The subplacenta was temporarily supplied by both the maternal and fetal blood systems, a rare condition among hystricognaths. The extraplacental trophoblast originating from the subplacenta was partly proliferative in mid gestation. In conclusion, the presented results indicated that only minor variations occurred in small-sized hystricognath species, independent of their systematic interrelationships. Previous views were supported that placentation in hystricognaths followed an extraordinary stable pattern, although the group had distinct habitats in South America and Africa that were separated 30-40 million years ago.     

Chorioallantoic placentation in Galea spixii (Rodentia,Caviomorpha, Caviidae)

Background  

Placentas of guinea pig-related rodents are appropriate animal models for human placentation because of their striking similarities to those of humans. To optimize the pool of potential models in this context, it is essential to identify the occurrence of characters in close relatives.     

New solvent-producing Clostridium sp. strains, hydrolyzing a wide range of polysaccharides, are closely related to Clostridium butyricum

Thirteen new Clostridium strains, previously isolated from soil and found to produce high amounts of solvents from glucose, hydrolyzed a great variety of α- and β-glycans, including raw starch, xylan, pectin, inulin and cellulose. The sequences of the PCR-amplified DNA fragments containing the variable 3′ part of one of the 16S rRNA genes were 99.5% identical. The macrorestriction pattern of two endonucleolytic digests of chromosomal DNA in the pulsed-field gel electrophoresis (PFGE) confirmed their high homogeneity on the DNA level. The complete 16S rRNA gene sequence of three selected strains was 99.8% identical to the 16S rRNA gene sequence from Clostridium butyricum and separates them from C. acetobutylicum. To the closely related four species of solventogenic clostridia a new group of strains has to be added, which has a great potential for the direct fermentation of biomass. Journal of Industrial Microbiology & Biotechnology (2001) 27, 329–335. Received 12 September 2000/ Accepted in revised form 25 July 2001     

Evolutionary transformations of chorioallantoic placental characters in rodentia with special reference to hystricognath species

The aim of this paper is to reconstruct the evolution of chorioallantoic placental characters in Rodentia. The analysis is based on pre-existing hypotheses of rodent relationships and the tracing of character evolution. Data on 64 rodent species of 49 genera are derived from the literature. New results refer to the hystricognath species Petromus typicus A. Smith, 1831 and Octodon degus (Molina, 1782). This comprehensive analysis confirms that the stem species pattern of Rodentia is characterised by a haemochorial placenta which is divided horizontally. Inside the placental labyrinth, fetal vessels and their trophoblastic external border build up a network through which the maternal blood flows. The trophoblastic tissue is one-layered, syncytial and possess a considerable surface extension. Within Rodentia, evolutionary transformations occurred on the macroscopic as well as the fine structural level. The results suggest that the stem species of Hystricognathi underwent transformations only on the macroscopic level, i.e., forming a ring-shaped arrangement of placental regions with centrally situated maternal arteries and the acquisition of a subplacenta. By contrast, in Muridae the chorioallantoic placenta shows derived features only in regard to the fine structure of the labyrinth, i.e. the interhaemal membrane is modified in composition, and the fetal capillary endothelium is fenestrated. Geomyoidea underwent transformations on both levels. Macroscopically, their placenta is modified into a hillock shape. Microscopically, the interhaemal membrane is formed by the cytotrophoblast. In addition to the mentioned transformations, some aspects of other fetal membrane differentiation in Rodentia are briefly discussed.     

msmsEval: tandem mass spectral quality assignment for high-throughput proteomics

Background  

In proteomics experiments, database-search programs are the method of choice for protein identification from tandem mass spectra. As amino acid sequence databases grow however, computing resources required for these programs have become prohibitive, particularly in searches for modified proteins. Recently, methods to limit the number of spectra to be searched based on spectral quality have been proposed by different research groups, but rankings of spectral quality have thus far been based on arbitrary cut-off values. In this work, we develop a more readily interpretable spectral quality statistic by providing probability values for the likelihood that spectra will be identifiable.     

Zell- und Zellkernveränderungen in den Nuclei habenulae und einigen Hypothalamuskernen bei experimentellen Eingriffen an der Schilddrüse

Zusammenfassung Histologische Beobachtungen und variationsstatistische Erhebungen über die Kerngröße im Diencephalon nach Thyreoidektomie, Thiouracilbehandlung und Thyroxinzufuhr an Albinoratten zeigten, daß eine Verhinderung der Thyroxin-Synthese bzw. Herabsetzung des Thyroxinspiegels im Blute zu hochgradigen Zell- und Zellkernveränderungen im Nucleus medialis habenulae führt. Die Veränderungen bestehen in einer Chromatolyse der Nervenzellen, einer hochgradigen Schrumpfung ihrer Kerne und in einigen Fällen auch in Zellausfall.Gleichzeitig ausgeführte kernvariationsstatistische Aufnahmen in verschiedenen Hypothalamusgebieten und im Hippocampus ergaben entweder überhaupt keine Kernveränderungen (Hippocampus, Nucleus suprachiasmaticus, Nucleus arcuatus) oder Veränderungen mit Dissoziation des Effektes nach Thyreoidektomie und Thiouracilbehandlung, nämlich Kernschwellung im Nucleus paraventricularis nach Thyreoidektomie, Kernschrumpfung im Nucleus dorsomedialis nach Thiouracilbehandlung.Diese Befunde werden als direkter histologischer Beweis für die Annahme gewertet, daß den Nuclei habenulae eine besondere Rolle bei der Steuerung der thyreotropen Hormonsekretion des Vorderlappens zukommt.     

The cDNA cloning and molecular evolution of reptile and pigeon lactate dehydrogenase isozymes

The cDNAs encoding lactate dehydrogenase isozymes LDH-A (muscle) and LDH-B (heart) from alligator and turtle and LDH-A, LDH-B, and LDH-C (testis) from pigeon were cloned and sequenced. The evolutionary relationships among vertebrate LDH isozymes were analyzed. Contrary to the traditional belief that the turtle lineage branched off before the divergence between the lizard/alligator and bird lineages, the turtle lineage was found to be clustered with either the alligator lineage or the alligator-bird clade, while the lizard lineage was found to have branched off before the divergence between the alligator/turtle and bird lineages. The pigeon testicular LDH-C isozyme was evidently duplicated from LDH-B (heart), so it is not orthologous to the mammalian testicular LDH-C isozymes.      

Bias-corrected paralinear and LogDet distances and tests of molecular clocks and phylogenies under nonstationary nucleotide frequencies

The statistical properties of the paralinear and LogDet distances under nonstationary nucleotide frequencies were studied. First, we developed formulas for correcting the estimation biases of the paralinear and LogDet distances, i.e., the bias-corrected distance is estimated by dc = d - 2var(d), where d and var(d) are the estimated distance and sampling variance, respectively. The performances of these formulas and the formulas for sampling variances were examined by computer simulation. Second, we developed a method for estimating the variance- covariance matrix of paralinear distances, so that statistical tests of DNA phylogenies can be conducted in the nonstationary case. Third, a new LogDet-based method for testing the molecular clock hypothesis was developed under nonstationary nucleotide frequencies.