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PubMed2006

A maternal-offspring coadaptation theory for the evolution of genomic imprinting.

Imprinted genes are expressed either from the maternally or paternally inherited copy only, and they play a key role in regulating complex biological processes, including offspring development and mother-offspring interactions. There are several competing theories attempting to explain the evolutionary origin of this monoallelic pattern of gene expression, but a prevailing view has emerged that holds that genomic imprinting is a consequence of conflict between maternal and paternal gene copies over maternal investment. However, many imprinting patterns and the apparent overabundance of maternally expressed genes remain unexplained and may be incompatible with current theory. Here we demonstrate that sole expression of maternal gene copies is favored by natural selection because it increases the adaptive integration of offspring and maternal genomes, leading to higher offspring fitness. This novel coadaptation theory for the evolution of genomic imprinting is consistent with results of recent studies on epigenetic effects, and it provides a testable hypothesis for the origin of previously unexplained major imprinting patterns across different taxa. In conjunction with existing hypotheses, our results suggest that imprinting may have evolved due to different selective pressures at different loci.

Adaptation, Biological↗
PubMedDate not supplied

DNA fingerprinting as an indicator of active transmission of multidrug-resistant tuberculosis in Poland.

OBJECTIVES: To use genetic fingerprinting to investigate the epidemiology of tuberculosis (TB) caused by Mycobacterium tuberculosis in Poland, a country with a relatively high incidence of tuberculosis, to improve TB control. DESIGN: One hundred M. tuberculosis isolates from 98 patients in the Institute of Tuberculosis and Lung Diseases in Warsaw from 1993 to 1995 and 85 isolates obtained from 50 patients in the Hospital of Lung Diseases in Lodz in 1996 were subjected to DNA restriction fragment length polymorphism (RFLP) analysis, using the insertion sequence IS6110 as a probe. RESULTS: IS6110-associated banding patterns of the M. tuberculosis isolates originating from different localities varied considerably, but isolates from Lodz had a higher degree of similarity. Strains with identical RFLP types were identified in patients of the same family or patients living in the same area, indicating active transmission. Of strains isolated in Warsaw, 45% were resistant to at least one drug, and 35% were resistant to two or more drugs and were classified as multidrug-resistant (MDR). Some drug-resistant isolates were found to have identical banding patterns and originated from epidemiologically linked cases. CONCLUSIONS: Active transmission of TB, including MDR TB, is occurring in Poland. Active measures must be taken to prevent the spread of drug-resistant TB in Poland and potentially, the rest of Europe.

Adolescent↗
PubMed1993

Pleomorphic ventricular tachycardia arising from a new site during antiarrhythmic drug therapy.

UNLABELLED: We analyzed the site of VT origin and the induction mode of VT in 9 patients who showed new VT morphologies with different bundle branch block patterns after administering antiarrhythmic drug(s). In all patients, VT exhibiting the clinical morphology was induced in the drug free state. (1) VT origin: In 6 patients, VTs showing LBBB pattern had a site of origin at the right ventricular free wall, and VTs with RBBB pattern originated from the left ventricular free wall. VT from the intraventricular septum of the right ventricle showed RBBB pattern in two patients and VT with LBBB pattern arose from the posteroseptum of the left ventricle in one patient. (2) VTs with new morphologies: After administering drug(s), VTs with new morphologies were induced in 18 studies and the mean cycle length of these VTs was not different from that in the control study. Among them, the induction mode was less aggressive in 4 of 7 drug studies and more aggressive in 1 study. (3) VTs with the same morphology: VTs with morphologies identical to those of the clinical VTs were induced in 15 studies. However, the drugs' effect was evident. The mean cycle length of these VTs was significantly prolonged, and VTs were induced by less aggressive modes or at longer coupling intervals. IN CONCLUSION: (1) After administering drug(s), different electrophysiologic characteristics were observed between the VTs with new morphologies and the VTs with the same morphology. (2) If a new VT was induced by less aggressive modes after administering drug(s), the drug(s) might act to facilitate inducibility: proarrhythmic effect.

Adolescent↗
PubMed1989

Identification of product-substrate pattern for erythrocyte membranes self-digestion using the original two-dimensional electrophoretic technique.

Ghost proteins immobilized in polyacrylamide gel after SDS-PAGE (first dimension) were degraded by endogenous membrane proteases. Fragments of the gels were submitted to SDS-PAGE (second dimension). Undigested proteins appeared on a diagonal, whereas products of proteolysis were evident below the substrates on electropherograms. The typical product patterns for spectrin, band 3, 4.1 and 4.2 proteins for human and bovine ghosts, are described.

Animals↗
PubMed1998

Continuing evolution of the pattern of quinolone resistance in Neisseria gonorrhoeae isolated in Sydney, Australia.

BACKGROUND AND OBJECTIVES: Multiple phenotypes of quinolone-resistant Neisseria gonorrhoeae isolated in Sydney since 1984 originated in Asia and increased in number and level of resistance in 1995. GOAL: To study the origins, characteristics, and infection pattern of quinolone-resistant Neisseria gonorrhoeae in Sydney from 1995 to 1997 and to compare these results with prior findings. STUDY DESIGN: Quinolone minimal inhibitory concentrations, phenotype, and geographic source of quinolone-resistant Neisseria gonorrhoeae isolated in Sydney from 1995 to 1997 were analyzed. RESULTS: Two hundred nineteen episodes of infection with quinolone-resistant Neisseria gonorrhoeae from 2,236 gonococcal isolates occurred during 1995 through 1997. The rate of isolation of quinolone-resistant Neisseria gonorrhoeae increased significantly at the end of 1996 and was maintained through 1997. The increase resulted from sustained domestic transmission of a limited number of phenotypes in heterosexual patients. CONCLUSION: The pattern of isolation of quinolone-resistant Neisseria gonorrhoeae in Sydney changed from the sporadic isolation of multiple phenotypes of imported quinolone-resistant Neisseria gonorrhoeae to a higher rate of endemic disease caused by a few subtypes. Alterations in antibiotic treatment regimens in the affected patient group were required.

Anti-Infective Agents↗
PubMed1987

Ultrasonographic differentiation of hepatocellular carcinoma from metastatic liver cancer.

Ultrasonographic features of tumor nodules in 64 patients with hepatocellular carcinoma and 87 with metastatic liver cancer were analyzed for differential diagnosis. Sonographic characteristics of hepatocellular carcinoma were the mosaic, posterior echo enhancement, and lateral shadow patterns, which were rarely observed in metastatic liver cancers. Small hepatocellular carcinomas, less than 3 cm in diameter, showed a hypoechoic pattern. Metastatic liver cancers originating from the gastrointestinal tract were frequently hyperechoic irrespective of their size and the bull's-eye-like pattern was specific for metastases from the lung. These results indicate that ultrasonography is useful for the differential diagnosis of hepatocellular carcinoma and metastatic liver cancer.

Carcinoma, Hepatocellular↗
PubMed2006

Prevalence and surgical significance of a high-origin anterior tibial artery.

PURPOSE: To assess the prevalence of proximal high-origin anterior tibial artery and its surgical significance. METHODS: 100 knees were prospectively studied using colour Doppler ultrasonography. No patient had a history of lower-limb arterial pathology or previous knee surgery. All ultrasound images were assessed by a single experienced vascular technician to eliminate inter-observer variability. RESULTS: The mean age of the patients was 56 years (range, 21-96 years). Prevalence of the high-origin anterior tibial arterial pattern was 6%, greater than that reported by previous angiographic or cadaveric studies. In all patients with high-origin anterior tibial artery, the artery was in direct contact with the posterior cortex of the tibia. CONCLUSION: This highlights the danger of using sharp instruments in knee procedures that involve extension of osteotomy to the posterior tibial cortex, particularly high-tibial osteotomy and total knee replacement. Knowledge of the anatomical variations in the branching of the popliteal artery is important because damage to its branches can be limb- or life-threatening.

Adult↗
PubMed1997

Limb deformity proteins: role in mesodermal induction of the apical ectodermal ridge.

During early limb development, distal tip ectoderm is induced by the underlying mesenchyme to form the apical ectodermal ridge. Subsequent limb growth and patterning depend on reciprocal signaling between the mesenchyme and ridge. Mice that are homozygous for mutations at the limb deformity (ld) locus do not form a proper ridge and the anteroposterior axis of the limb is shortened. Skeletal analyses reveal shortened limbs that involve loss and fusion of distal bones and digits, defects in both anteroposterior and proximodistal patterning. Using molecular markers and mouse-chick chimeras we examined the ridge-mesenchymal interactions to determine the origin of the ld patterning defects. In the ld ridge, fibroblast growth factor 8 (Fgf8) RNA is decreased and Fgf4 RNA is not detected. In the ld mesenchyme, Sonic hedgehog (Shh), Evx1 and Wnt5a expression is decreased. In chimeras between ld ectoderm and wild-type mesenchyme, a ridge of normal morphology and function is restored, Fgf8 and Shh are expressed normally, Fgf4 is induced and a normal skeletal pattern arises. These results suggest that the ld mesenchyme is unable to induce the formation of a completely functional ridge. This primary defect causes a disruption of ridge function and subsequently leads to the patterning defects observed in ld limbs. We propose a model in which ridge induction requires at least two phases: an early competence phase, which includes induction of Fgf8 expression, and a later differentiation phase in which Fgf4 is induced and a morphological ridge is formed. Ld proteins appear to act during the differentiation phase.

Animals↗
PubMed1999

Developmental expression and cellular origin of the laminin alpha2, alpha4, and alpha5 chains in the intestine.

Laminins are extracellular matrix glycoproteins that are involved in various cellular functions, including adhesion, proliferation, and differentiation. In this study, we examine the expression patterns and the cellular origins of the laminin alpha2, alpha4, and alpha5 chains in the developing mouse intestine and in in vitro mouse/chick or chick/mouse interspecies hybrid intestines. In situ hybridization and Northern blot analysis revealed that mRNA levels for all three laminin alpha chains are highest in the fetal intestine undergoing intense morphogenetic movements. Laminin alpha4 mRNA and polypeptide are associated with mesenchyme-derived cell populations such as endothelium and smooth muscle. In contrast, laminin alpha2 and alpha5 chains participate in the structural organization of the subepithelial basement membrane and, in the mature intestine, show a complementary pattern of expression. All three laminin alpha chains occur in the smooth muscle basement membrane, with a differential expression of laminin alpha5 chain in the circular and longitudinal smooth muscle layers. The cellular origin of laminin alpha2 and alpha5 chains found in the subepithelial cell basement membrane was studied by immunocytochemical analysis of mouse/chick or chick/mouse interspecies hybrid intestines at various stages of development using mouse-specific antibodies. Laminin alpha2 was found to be deposited into the basement membrane exclusively by mesenchymal cells, while the laminin alpha5 chain was deposited by both epithelial and mesenchymal cells in an apparently developmentally regulated pattern. We conclude that (1) multiple laminin alpha chains are expressed in the intestine, implying specific roles for individual laminin isoforms during intestinal development, and (2) reciprocal epithelial/mesenchymal interactions are essential for the formation of a structured subepithelial basement membrane.

Animals↗
PubMed1992

Mechanisms of spontaneous shift of surface electrocardiographic configuration during ventricular tachycardia.

OBJECTIVES: The aim of this study was to examine, with multichannel direct cardiac mapping techniques, the mechanisms of spontaneous shift of the QRS configuration in the surface electrocardiogram during episodes of ventricular tachycardia. BACKGROUND: Ventricular tachycardias demonstrating a spontaneous shift in their surface electrocardiographic (ECG) features are occasionally encountered. It is not known whether such changes in configuration are primarily due to a significant change in the tachycardia site of origin or represent alterations in patterns of endocardial and epicardial activation. Knowledge of these features would be helpful, particularly when ablative therapy is considered for the arrhythmias. METHODS: During map-directed cardiac surgery, episodes of ventricular tachycardia were mapped from 224 epicardial and endocardial sites. Episodes of pleomorphic tachycardia were identified and isochronal maps of endocardial and epicardial activation were constructed from representative beats before and after the change in configuration. RESULTS: From 52 consecutive patients who underwent detailed intraoperative mapping, 9 patients with pleomorphic ventricular tachycardia were identified in whom 14 episodes of spontaneous shift occurred. An analysis of the epicardial activation patterns revealed that the sites of earliest epicardial breakthrough showed significant alteration at the time of QRS shift in all occurrences. In 10 of these shift episodes, however, the sites of tachycardia origin, located on the endocardial surface, remained closely adjacent (< 2 cm apart). Although these sites of origin remained relatively constant, significant alterations in the patterns of endocardial activation were seen in most episodes. These included changes in the direction of propagation of the wave front of activation and shifts between monoregional and figure eight patterns of activation. CONCLUSIONS: In most episodes of pleomorphic ventricular tachycardia, the arrhythmia site of origin remains relatively constant. However, patterns of epicardial activation do undergo significant change and appear to be the major determinant of the QRS configuration on the surface ECG.

Cardiac Pacing, Artificial↗
PubMed1992

Computer-assisted pattern recognition model for the identification of slowly growing mycobacteria including Mycobacterium tuberculosis.

We present a computerized pattern recognition model used to speciate mycobacteria based on their restriction fragment length polymorphism (RFLP) banding patterns. DNA fragment migration distances were normalized to minimize lane-to-lane variability of band location both within and among gels through the inclusion of two internal size standards in each sample. The computer model used a library of normalized RFLP patterns derived from samples of known origin to create a probability matrix which was then used to classify the RFLP patterns from samples of unknown origin. The probability matrix contained the proportion of bands that fell within defined migration distance windows for each species in the library of reference samples. These proportions were then used to compute the likelihood that the banding pattern of an unknown sample corresponded to that of each species represented in the probability matrix. As a test of this process, we developed an automated, computer-assisted model for the identification of Mycobacterium species based on their normalized RFLP banding patterns. The probability matrix contained values for the M. tuberculosis complex, M. avium, M. intracellulare, M. kansasii and M. gordonae species. Thirty-nine independent strains of known origin, not included in the probability matrix, were used to test the accuracy of the method in classifying unknowns: 37 of 39 (94.9%) were classified correctly. An additional set of 16 strains of known origin representing species not included in the model were tested to gauge the robustness of the probability matrix. Every sample was correctly identified as an outlier, i.e. a member of a species not included in the original matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA, Bacterial↗
PubMed1990

Development of the mechanoreceptive lateral-line system in the axolotl: placode specification, guidance of migration, and the origin of neuromast polarity.

The mechanosensory lateral-line system offers a unique opportunity to study a wide variety of developmental phenomena, including cell migration, the origin of polarity, and pattern formation. In this study, we use a series of transplantation experiments to examine some of the factors affecting the origin of the lateral-line placodes, the establishment of sensory organ polarity and placement, and the guidance of cell migration in the Mexican axolotl (Ambystoma mexicanum). We find that placode-forming ectoderm is at least partially specified as early as the beginning of neurulation, and we suggest that this may be a result of early processes involved in neural induction. Furthermore, we find that the migration of the primordia on the body depends on the presence of both the ectoderm and the subjacent mesoderm for guidance. Sensory organ polarity on the body appears to be the result of an interaction between the primordia, which deposit organs of set polarity relative to the direction of migration, and the substrate, which determines the direction of migration. Spacing of the organs is independent of the substrate, and may be due to an intrinsic property of either the primordia or the emerging organs themselves. Finally, we suggest that the lateral-line primordia are guided, as they migrate, by a contact guidance mechanism.

Ambystoma↗
PubMed2004

Gliosarcoma arising from an anaplastic ependymoma: a case report of a rare entity.

We report the first case of a gliosarcoma arising from an anaplastic ependymoma and the second case of gliosarcoma arising from any type of ependymal neoplasm. The patient was a 48-year-old woman with a solid and cystic, peripherally enhancing, 7-cm right frontal mass lesion. Histologically, the lesion displayed characteristics of anaplastic ependymoma (grade III, World Health Organization scale). The tumor recurred despite multiple cycles of postoperative radiation and chemotherapy. After the fourth recurrence, the tumor displayed a biphasic pattern of differentiation. The first pattern was similar to the original anaplastic ependymoma, whereas there was a second new sarcomatous pattern resembling fibrosarcoma that was admixed with and overrunning the ependymal component. The spectrum of gliosarcoma is therefore expanded to include not only astrocytic and oligodendroglial components but ependymal components as well.

Brain Neoplasms↗
PubMed2005

Orientation effects on indexing of electron backscatter diffraction patterns.

Automated Electron Backscatter Diffraction (EBSD) has become a well-accepted technique for characterizing the crystallographic orientation aspects of polycrystalline microstructures. At the advent of this technique, it was observed that patterns obtained from grains in certain crystallographic orientations were more difficult for the automated indexing algorithms to accurately identify than patterns from other orientations. The origin of this problem is often similarities between the EBSD pattern of the correct orientation and patterns from other orientations or phases. While practical solutions have been found and implemented, the identification of these problem orientations generally occurs only after running an automated scan, as problem orientations are often readily apparent in the resulting orientation maps. However, such an approach only finds those problem orientations that are present in the scan area. It would be advantageous to identify all regions of orientation space that may present problems for automated indexing prior to initiating an automated scan, and to minimize this space through the optimization of acquisition and indexing parameters. This work presents new methods for identifying regions in orientation space where the reliability of the automated indexing is suspect prior to performing a scan. This methodology is used to characterize the impact of various parameters on the indexing algorithm.

Journal Article↗
PubMed2003

Origin and evolution of Schistosoma japonicum.

In his hypothesis on the coevolution of Asian schistosomes and snails, Davis implies that the ancestors of the Schistosoma japonicum and S. indicum species group were African and arrived in Asia via the Indian plate. This paper briefly reviews molecular phylogenetic relationships among species of the genus Schistosoma to test Davis' theory about the origin and evolution of S. japonicum. All analyses using DNA base sequences, mitochondrial genome gene order and C-banding patterns suggest that Schistosoma originated in Asia and not Africa.

Africa↗
PubMed2004

Origin of nasal polyps: an endoscopic autopsy study.

OBJECTIVES/HYPOTHESIS: To further elucidate the natural history, etiology, and pathogenesis of nasal polyps, the present study of their anatomical site of origin was undertaken. The possibility for preferred areas or certain patterns in the places of origin was also considered. STUDY DESIGN: Autopsies were examined consecutively. METHODS: Endoscopic examination of the nasal cavity and paranasal sinuses, including endoscopic sinus surgery, was performed in 69 autopsies. The place of origin and attachment of each polyp was meticulously described. Polyps were photographically documented in situ and removed, together with the corresponding mucosa, for later histological examination. The cause of death of the patients was either cardiopulmonary disease or malignant diseases. Median age was 73 years (age range, 47-94 y). RESULTS: Nasal polyps were found in 22 of the 69 autopsies, corresponding to a frequency of 32%. In all, 54 polyps were found. Thirty-nine polyps were small (length, 2-5 mm), 10 were medium-sized, and 5 were large. No complaints of symptoms from the nasal polyps were registered. Most of the polyps (40 of 54 [74%]) originated in relation to sinus outlets. Most of these (34 of 54 [63%]) were found in the middle or superior meatus (13 of 54 [24%]). CONCLUSION: The results seemed to indicate that the frequency of nasal polyps is high and that most of the polyps originate from the mucosa of the ostia, clefts, and recesses in the ostiomeatal complex where the initial stage of sinonasal polyposis seems to take place. Continuous postmortem studies in autopsy materials and systematic endoscopic examinations for "silent," asymptomatic nasal polyps in various groups of patients will lead to a better understanding of the natural history of nasal polyps.

Aged↗
PubMed1989

[Anatomic study of the coronary arteries in transposition of great vessels].

The authors studied 64 hearts presenting transposition of the great arteries, in order to evaluate the pattern of distribution and origin of the main coronary arteries. Regarding the origin in each sinus of Valsalva, there was no significant difference with the data from the literature. It was also evaluated the precise site of origin inside the sinuses, which were divided in three thirds: the medial and those adjacent to the valvar commissures. We observed that, although the coronary ostia took origin from the medial third in more than half of the cases, there was some variation when considering the different patterns of distribution. This observations is relevant, since, when Jatene's procedure is considered, the surgical disinsertion of a coronary artery may put at risk the valvar leaflet, when the ostium is near the commissure.

Child↗
PubMed1994

Cutaneous melanoma.

Between the early 1960s and the late 1980s, the incidence of melanoma increased at a rate of 3-7% per year in populations of mainly European origin. Corresponding trends were observed in mortality. Higher rates of increase in incidence were observed in a few populations (eg 8.9% per year in Hawaii whites). With the exception of Japan and possibly Puerto Rico, incidence rates of melanoma have remained stable in the few populations of mainly non-European origin for which reliable incidence data were available. A comparison of age specific trends in incidence and mortality in populations of mainly European origin showed two general patterns: a continuous increase in incidence in all age groups but with moderation or cessation of the previous rising trend in mortality in younger people in more recent time periods (eg Canada, continental USA, Denmark and the UK) and recent moderation or cessation of both incidence and mortality trends in younger people (eg New Zealand and, possibly, Hawaii whites). The first of these two patterns appeared to be the most common. Studies of site specific trends in incidence in 13 populations indicate that the highest rates of increase have generally been for melanomas on the trunk and the lowest for those on the head and neck. There is weak evidence to suggest that the rate of increase on the lower limbs has been greater in women than in men. Studies of incidence trends in the 1980s by thickness of melanoma in seven populations show that relative and absolute incidence has increased most for the thinnest melanomas and least for the thickest lesions. Increasing detection, earlier diagnosis and a real rise may together explain the increase in incidence of melanoma. The increases in mortality suggest that incidence has really increased, and the recent moderation in mortality trends may be explained by improved survival from melanoma due, most likely, to increasingly early diagnosis. In some populations, it may also indicate that the incidence increases are coming to an end. The disproportionately increasing incidence of thin melanoma, the divergence between incidence and mortality trends and the recent sharp increases in incidence in some populations suggest that earlier diagnosis or greater detection of less aggressive melanomas may have contributed to the incidence trends. A progressive change from predominantly occupational to predominantly recreational patterns of sun exposure is the most likely cause of increasing real incidence of melanoma in populations of mainly European origin.

Adolescent↗