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PubMed1999

Neocognitron's parameter tuning by genetic algorithms.

The further study on the sensitivity analysis of Neocognitron is discussed in this paper. Fukushima's Neocognitron is capable of recognizing distorted patterns as well as tolerating positional shift. Supervised learning of the Neocognitron is fulfilled by training patterns layer by layer. However, many parameters, such as selectivity and receptive fields are set manually. Furthermore, in Fukushima's original Neocognitron, all the training patterns are designed empirically. In this paper, we use Genetic Algorithms (GAs) to tune the parameters of Neocognitron and search its reasonable training pattern sets. Four contributions are claimed: first, by analyzing the learning mechanism of Fukushima's original Neocognitron, the correlations amongst the training patterns are claimed to affect the performance of Neocognitron, tuning the Neocognitron's number of planes is equivalent to searching reasonable training patterns for its supervised learning; second, a GA-based supervised learning of the Neocognitron is carried out in this way, searching the parameters and training patterns by GAs but specifying the connection weights by training the Neocognitron; third, other than traditional GAs which are unsuitable for the large searching space of training patterns set, the cooperative coevolution is incorporated to play this role; fourth, an effective fitness function is given out when applying the above methodology into numeral recognition. The evolutionary computation in our initial experiments is implemented based on the original training pattern set, e.g. the individuals of the population are generated from Fukushima's original training patterns during initialization of GAs. The results prove that our correlation analysis is reasonable, and show that the performance of a Neocognitron is sensitive to its training patterns, selectivity and receptive fields, especially, the performance is not monotonically increasing with respect to the number of training patterns, and this GA-based supervised learning is able to improve Neocognitron's performance.

Cognition↗

PubMed2005

Computer simulation studies of microcrystalline cellulose Ibeta.

Molecular mechanics (MM) simulations have been used to model two small crystals of cellulose Ibeta surrounded by water. These small crystals contained six different extended surfaces: (110), (11 0), two types of (100), and two types of (010). Significant changes took place in the crystal structures. In both crystals there was an expansion of the unit cell, and a change in the gamma angle to almost orthogonal. Both microcrystals developed a right-hand twist of about 1.5 degrees per cellobiose unit, similar to the twisting of beta-sheets in proteins. In addition, in every other layer, made up of the unit cell center chains, a tilt of the sugar rings of 14.8 degrees developed relative to the crystal plane as a result of a transition of the primary alcohol groups in these layers away from the starting TG conformation to GG. In this conformation, these groups made interlayer hydrogen bonds to the origin chains above and below. No change in the primary alcohol conformations or hydrogen-bonding patterns in the origin chain layers was observed. Strong localization of the adjacent water was found for molecules in the first hydration layer of the surfaces, due to both hydrogen bonding to the hydroxyl groups of the sugar molecules and also due to hydrophobic hydration of the extensive regions of nonpolar surface resulting from the axial aliphatic hydrogen atoms of the 'tops' of the glucose monomers. Significant structuring of the water was found to extend far out into the solution. It is hypothesized that the structured layers of water might present a barrier to the approach of cellulase enzymes toward the cellulose surfaces in enzyme-catalyzed hydrolysis, and might inhibit the escape of soluble products, contributing to the slow rates of hydrolysis observed experimentally. Since the water structuring is different for the different surfaces, this might result in slower hydrolysis rates for some surfaces compared to others.

Carbohydrate Conformation↗

PubMed1996

Cultural aspects of African American eating patterns.

The high mortality from diet-related diseases among African Americans strongly suggests a need to adopt diets lower in total fat, saturated fat and salt and higher in fiber. However, such changes would be contrary to some traditional African American cultural practices. Focus group interviews were used to explore cultural aspects of eating patterns among low- and middle-income African Americans recruited from an urban community in Pennsylvania. In total, 21 males and 32 females, aged 13-65+ years were recruited using a networking technique. Participants identified eating practices commonly attributed to African Americans and felt that these were largely independent of socioeconomic status. They were uncertain about links between African American eating patterns and African origins but clear about influences of slavery and economic disadvantage. The perception that African American food patterns were characteristically adaptive to external conditions, suggest that, for effective dietary change in African American communities, changes in the food availability will need to precede or take place in parallel with changes recommended to individuals. Cultural attitudes about where and with whom food is eaten emerged as being equivalent in importance to attitudes about specific foods. These findings emphasize the importance of continued efforts to identify ways to increase the relevance of cultural context and meanings in dietary counseling so that health and nutrition interventions are anchored in values as perceived, in this case, by African Americans.

Adolescent↗

PubMed2002

Anatomical variations of the arterial pattern in the right hemiliver.

The arterial supply to the right hemiliver was studied in 80 liver casts. The arteries were divided into 10 groups according to their origin and branching pattern. The right hemiliver was supplied by one artery in 96% of cases and by two arteries in 4%. When there was only one artery it originated from the proper hepatic artery in 73/77 cases and from the superior mesenteric artery in 4/77 cases. The replacing right hepatic artery which originated from the superior mesenteric vessel supplied the whole right hemiliver in 5% of cases. The incomplete replacing right hepatic artery which supplied only a part of the right hemiliver was found in 4% of cases. The anterior section (segments 5 and 8) was supplied by one artery in 61%, by two arteries in 30% and by three arteries in 9% of cases. The posterior section (segments 6 and 7) was supplied by one artery in 66%, by two arteries in 31% and by three arteries in 3% of cases. Segments 5 and 7 were predominantly supplied by one artery, whereas segments 6 and 8 by two arteries.

Autopsy↗

PubMed2002

Anatomical variations of the arterial pattern in the left hemiliver.

The arterial supply to the left hemiliver was studied in 70 liver casts. The arteries were divided into 15 groups according to their origin and branching pattern. The left hemiliver was supplied by one artery in 53% of cases, by two arteries in 40% and by three arteries in 7%. The left hepatic artery, which originated from the proper hepatic artery, supplied all three left segments in 39% of specimens. The replacing left hepatic artery, which originated from the left gastric artery, supplied the whole left hemiliver in 3% of cases. The incomplete, replacing left hepatic artery supplied segments 2, 3 and a part of segment 4 in 6% of cases, and only segments 2 and 3 in 11%. There was one segmental artery for segment 2 in 86%, and two in 14%. Segment 3 was supplied by one artery in 87%, and by two in 13%. Segment 4 was supplied by one artery in 39% of cases, by two arteries in 43%, by three in 14% and by four arteries in 4%.

Arteries↗

PubMed1980

Glial-released proteins in clonal cultures and their modulation by hydrocortisone.

Rat glial C6 cells release into the culture medium a reproducible spectrum of soluble proteins of 12 major peaks over a broad molecular weight range as determined by fractionation on SDS-gel electrophoresis. Exposing C6 monolayers to hydrocortisone (HC) results in a selective alteration in the pattern of glial-released protein (GRP). The selective HC-induced increase or decrease in GRP peaks is specific to HC in that 17 beta-estradiol, dibutyryl cyclic AMP, isoproterenol and melatonin exert either no detectable or a qualitatively different influence on the GRP pattern. The HC influence is dose dependent over a physiological range of concentrations from 10(-9) to 10(-6) M. Differences in culture age and in subclones of C6 can influence both the normal and the HC-induced pattern of GRP. The origin of th GRP is unknown, but pattern reproducibility, viability tests, surface labeling studies and metabolic labeling studies of soluble and particulate compartment proteins and glycoproteins support the position that cell lysis is not an important source of GRP. More importantly, these studies indicate that GRP and HC-induced changes in GRP pattern are physiologically significant aspects of glial cell behavior.

Animals↗

PubMed1988

Patterning of connective tissues in the head: discussion report.

The three papers presented by Noden, Thorogood and Lumsden in this session encompassed the connective tissues as broadly defined, i.e. soft (fibrous) connective tissue, cartilage, bone, muscle and the dental tissues, enamel and dentine, and utilized a variety of experimental techniques on both avian and mammalian embryos to explore specificity and patterning of the vertebrate head. Whether similar developmental processes pattern homologous structures in different Vertebrate classes (Amphibia, Aves, Mammalia) was discussed with reference to patterning of the cranial musculature, chondrocranium and dental tissues. A number of challenging ideas emerged during this session. Does the premigratory neural crest consist of a homogenous population of totipotent cells or of subpopulations of bi- or tripotential cells? Is fundamental patterning of the head an early embryonic event, perhaps specified during primary embryonic induction or the consequence of neuroepithelial folding, brain growth, inductive interactions and/or spatially and temporally distributed extracellular matrix products? Can the fact that mesoderm and angioblasts do not display distinctive patterning that relates to their particular embryologic origins be extrapolated to patterning in general? How does the documentation of an odontogenic trunk neural crest in mammals affect our theories of how patterning mechanisms arose or were modified during vertebrate evolution?

Animals↗

PubMed2001

Cardiovascular mortality in twins and the fetal origins hypothesis.

The intrauterine growth patterns for twins are characterized by normal development during the first two trimesters and reduced growth during the third trimester. According to the fetal origins hypothesis this growth pattern is associated with risk factors for cardiovascular morbidity and mortality. We studied cause-specific mortality of 19,986 Danish twin individuals from the birth cohorts 1870-1930 followed from 1952 through 1993. Despite the large sample size and follow-up period we were not able to detect any difference between twins and the general population with regard to all-cause mortality or cardiovascular mortality. Hence, the intrauterine growth retardation experienced by twins does not result in any "fetal programming" of cardiovascular diseases. There is still an important role for twins (and other sibs) to play in the testing of the fetal origins hypothesis, namely in studies of intra-pair differences, which can assess the role of genetic confounding in the association between fetal growth and later health outcome.

Aged↗

PubMed1996

Porocarcinoma of the heel. A case report with unusual histologic features.

BACKGROUND: Eccrine porocarcinoma is an uncommon neoplasm of the intraepidermal sweat gland duct. METHODS: A case of porocarcinoma of the right heel in a male age 51 years is described with a review of pertinent literature. The surgically excised neoplasm was evaluated by routine histology and transmission electron microscopy. RESULTS: The porocarcinoma showed extensive nuclear pleomorphisms with frequent, multinucleated tumor giant cells, focal epidermotrophic spread within the epidermis, a peripheral, eccrine syringofibroadenoma-like growth pattern, and an origin in a contiguous eccrine poroma. Ultrastructurally, the squamous tumor cells contained rare intracytoplasmic lumens. CONCLUSIONS: The extensive nuclear pleomorphism with frequent tumor giant cells was an unusual feature of the porocarcinoma. Its epidermotrophic spread within the epidermis and its origin in a contiguous eccrine poroma supported the diagnosis of porocarcinoma. The eccrine syringofibroadenoma-like growth pattern in the periphery of the tumor was a unique and previously undescribed feature of the porocarcinoma. The presence of intracytoplasmic lumens in squamous tumor cells mimicked embryonic development of the intraepidermal sweat gland duct.

Acrospiroma↗

PubMed2006

Combining genetics and population history in the study of ethnic diversity in the People's Republic of China.

Genomic data have increasingly been used to complement linguistic, archeological, and anthropological evidence in reconstructing the origins and migratory patterns of modern humans. East Asia is a particular hotspot of human migration, especially mainland China, where a large number of human fossils have been unearthed and more than 20% of the world's population now resides. There are 56 officially recognized ethnic populations (minzu) in China. In the present study we investigated the ancestry and genetic diversity of nine populations: the majority Han of Liaoning Province; the Miao, Yao, Kucong, and Tibetan communities of Yunnan Province in southwest China; and four Muslim populations, the Hui, Bonan, Dongxiang, and Sala from central and northern China. We used both biparental and uniparental markers to determine patterns of diversity at autosomal, mitochondrial, and Y-chromosome loci. The study populations displayed several paternal origins but restricted maternal ancestries. From the Y-chromosome data in particular, major demographic changes, such as the Neolithic population expansion and more recent historical events including migration along the Silk Road, could be inferred. Specific aspects of the internal structure and organization of the study populations, including endogamy and consanguinity, were uncovered using autosomal markers. However, we encountered interpretive problems in terms of the definition of the present-day ethnic study populations in China, which appear to reflect past and present political as well as genetic influences.

China↗

PubMed1999

Bilateral double axillary artery: embryological basis and clinical implications.

An unusual bilateral variation in the arterial pattern of the axilla was observed in an embalmed cadaver. Each axilla contained two axillary arteries of similar origins but different patterns of branching and fate. The first part of each axillary artery was a single vessel as is the norm. It gave off a supreme thoracic artery and then bifurcated into two medium-sized arteries hence referred to as regular and variant. The variant artery ran in an antero-medial course, partly covered by the one axillary vein. The regular artery gave off the thoracoacromial and two posterior branches from its second part, the anterior and posterior humeral circumflex arteries from its third part, and then continued as the brachial artery with all the usual branches except the profunda brachii on the right side. The variant gave off five arteries from the second part, a thoracoacromial artery, two separate long thoracic arteries each with a branch that ran along the intercostobrachial nerve to the arm, and two posterior branches. In the third part of the variant, the subscapular artery arose with its usual branches plus a common origin for two additional humeral circumflex arteries. The variant terminated as the profunda brachii artery to the right side while on the left side it terminated in muscular branches to the triceps. Hence, the arterial blood supply to the upper limb, and the axillary region in particular, was shared on both sides by two major arteries instead of one. These two arteries emanated from the first part of the axillary artery and may represent persisting branches of the capillary plexus of the developing limb buds. The findings have an embryological basis and clinical relevance considering the frequency of procedures in this region.

Aged↗

PubMed1986

Paper chromatography of urinary amino acids. A 30 year survey of dietary influences on the normal pattern, and patients' results.

In the clinical laboratory, paper chromatography is still the most useful, simple, inexpensive procedure for initial identification of abnormalities of amino acid excretion. The results of its use for more than 8000 paediatric and adult renal patients is surveyed. Nonspecific generalized aminoaciduria was the most frequent abnormality found, comprising some 70% of abnormal results, with cystine-lysinuria the next most common. The identification of the abnormal excretory pattern of amino acids as distinct from the normal was complicated by the effects of the New Zealand diet. In particular, valine, citrulline, hydroxyproline and glutamic acid are found in considerable amounts as part of the normal pattern. Their dietary origin is discussed. Varying mixtures of monosaccharides and disaccharides occurred in association with a range of amino acid patterns.

Adult↗

PubMed1992

Pattern dependent form of synaptic modification and its quantal origins.

Presynaptic mechanisms of post-activation changes of synaptic efficacy have been quantitatively reconstructed via computer simulations with the previously suggested double-barrier quantal model of a chemical synapse. Successful in predicting the global changes in synaptic efficacy during and after short trains of presynaptic impulses, computer reconstructions have revealed in the post-activation period the stimulus dependent form of synapse modification from short-term to longer-term plasticity. An analysis of the quantal origins of the phenomenon suggests semantic or S-pattern as the trigger of the phenomenon. The property of a semantic pattern to modify synaptic plasticity is presented in the form of the rule of S-pattern dependent synaptic modification or S-modification.

Kinetics↗

PubMed2004

Topology and robustness in the Drosophila segment polarity network.

A complex hierarchy of genetic interactions converts a single-celled Drosophila melanogaster egg into a multicellular embryo with 14 segments. Previously, von Dassow et al. reported that a mathematical model of the genetic interactions that defined the polarity of segments (the segment polarity network) was robust (von Dassow et al. 2000). As quantitative information about the system was unavailable, parameters were sampled randomly. A surprisingly large fraction of these parameter sets allowed the model to maintain and elaborate on the segment polarity pattern. This robustness is due to the positive feedback of gene products on their own expression, which induces individual cells in a model segment to adopt different stable expression states (bistability) corresponding to different cell types in the segment polarity pattern. A positive feedback loop will only yield multiple stable states when the parameters that describe it satisfy a particular inequality. By testing which random parameter sets satisfy these inequalities, I show that bistability is necessary to form the segment polarity pattern and serves as a strong predictor of which parameter sets will succeed in forming the pattern. Although the original model was robust to parameter variation, it could not reproduce the observed effects of cell division on the pattern of gene expression. I present a modified version that incorporates recent experimental evidence and does successfully mimic the consequences of cell division. The behavior of this modified model can also be understood in terms of bistability in positive feedback of gene expression. I discuss how this topological property of networks provides robust pattern formation and how large changes in parameters can change the specific pattern produced by a network.

Animals↗

PubMed1997

Development-dependent inheritance of 5-azacytidine-induced epimutations in triticale: analysis of rDNA expression patterns.

Genomic imprinting of rye origin rDNA sequences in triticale is modulated by DNA methylation responsible for ontogenic expression patterns of those sequences. Considering the dynamic nature of these phenomena, we evaluated the influence of plant development on the inheritance of modified rye rDNA expression patterns. DNA hypomethylation was induced in triticale by 5-azacytidine (5AC) treatments at distinct developmental stages of M1 plants, and expression patterns were analysed in M2. The activity of rye origin rRNA genes in progeny of untreated and 5AC-treated plants was evaluated by silver staining in meristematic root tip cells and in meiocytes at diplotene. In the progeny of 5AC-treated plants, a significant increase in rye rDNA expression was observed, contrasting with the residual activity in untreated plants. Significant differential effects of 5AC treatments were observed in M2 plants and correlated with the M1 plant developmental stage in which DNA hypomethylation was induced. Hypotheses to explain the origin of those differences are discussed here.

Antimetabolites, Antineoplastic↗

PubMed1996

Characterization of Trichuris skrjabini by isoenzyme gel electrophoresis: comparative study with Trichuris ovis.

Morphological and biometric studies were performed in Trichuris skrjabini (Baskakov, 1924) collected from the caecum of Capra hircus. The LDH (EC 1.1.1.27.), G6PD (EC 1.1.1.49.), GPI (EC 5.3.1.9.), MDH (EC 1.1.1.37) and malic enzyme (ME) (EC 1.1.1.40) isoenzymatic patterns of T. skrjabini were determined by starch gel electrophoresis. The G6PD and GPI isoenzymatic patterns of T. skrjabini displayed two anodic bands for both enzymes: one fast migration band and one band near the origin. This isoenzymatic pattern was interpreted as two gene loci encoding both enzymes. The LDH isoenzymatic pattern of T. skrjabini was characterized by the presence of a cathodically migrating band, while the MDH isoenzymatic pattern showed a very slow cathodic band. These two phenotypes were interpreted as the expression of a homozygous state of a gene locus for LDH and MDH in T. skrjabini. The ME isoenzymatic pattern was characterized by the presence of a single anodic band. Further, comparative isoenzymatic studies were carried out between T. skrjabini and T. ovis. The different G6PD, GPI, LDH, MDH and ME isoenzymatic patterns observed for both species allowed us to distinguish them and therefore to use isoenzymatic patterns as a diagnostic tool to differentiate species of Trichuris.

Animals↗

PubMed1996

Chondrocytic cell differentiation in clear cell chondrosarcoma.

Clear cell chondrosarcoma is a rare mesenchymal neoplasm of unclear differentiation. Besides having a chondrogenic nature, an osteogenic differentiation was also proposed. In this study, expression analysis of extracellular matrix genes, which are specific for different mesenchymal cell differentiation pathways, were used to get a better understanding of origin and differentiation pattern of the clear cell chondrosarcoma tumor cells. Our in situ analysis of two cases shows that (1) chondrocytic cell differentiation as marked by the expression of cartilage collagen type II and proteoglycans is a characteristic feature within the development of the neoplasm, (2) multifocal chondrocyte hypertrophy as shown by the expression of type X collagen does occur, and (3) no significant expression of collagen type I, the main gene product of osteoblastic cells, is found by the neoplastic cells. Thus, our study indicates that clear cell chondrosarcoma shows a chondrogenic, but not osteogenic, differentiation and represents a true chondrosarcoma. The unusual scarcity of its extracellular and the multifocal expression of type X collagen marks clear cell chondrosarcoma as a chondrosarcoma tumor entity of a particular cell differentiation pattern. The expression of cartilage type collagens represents a distinct marker from bone metastases of clear cell neoplasms of other origins.

Adult↗

PubMed2005

Characterization of Mycobacterium caprae isolates from Europe by mycobacterial interspersed repetitive unit genotyping.

Mycobacterium caprae, a recently defined member of the Mycobacterium tuberculosis complex, causes tuberculosis among animals and, to a limited extent, in humans in several European countries. To characterize M. caprae in comparison with other Mycobacterium tuberculosis complex members and to evaluate genotyping methods for this species, we analyzed 232 M. caprae isolates by mycobacterial interspersed repetitive unit (MIRU) genotyping and by spoligotyping. The isolates originated from 128 distinct epidemiological settings in 10 countries, spanning a period of 25 years. We found 78 different MIRU patterns (53 unique types and 25 clusters with group sizes from 2 to 9) but only 17 spoligotypes, giving Hunter-Gaston discriminatory indices of 0.941 (MIRU typing) and 0.665 (spoligotyping). For a subset of 103 M. caprae isolates derived from outbreaks or endemic foci, MIRU genotyping and IS 6110 restriction fragment length polymorphism were compared and shown to provide similar results. MIRU loci 4, 26, and 31 were most discriminant in M. caprae, followed by loci 10 and 16, a combination which is different than those reported to discriminate M. bovis best. M. caprae MIRU patterns together with published data were used for phylogenetic inference analysis employing the neighbor-joining method. M. caprae isolates were grouped together, closely related to the branches of classical M. bovis, M. pinnipedii, M. microti, and ancestral M. tuberculosis, but apart from modern M. tuberculosis. The analysis did not reflect geographic patterns indicative of origin or spread of M. caprae. Altogether, our data confirm M. caprae as a distinct phylogenetic lineage within the Mycobacterium tuberculosis complex.

Animals↗