Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Origination patterns”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources

Shapes and sounds as self-objects in learning geography.

The pleasure which some children find in maps and map reading is manifold in origin. Children cathect patterns of configuration and color and derive joy from the visual mastery of these. This gratification is enhanced by the child's knowledge that the map represents something bigger than and external to itself. Likewise, some children take pleasure in the pronunciation of names themselves. The phonetic transcription of multisyllabic names is often a plearurable challenge. The vocalized name has its origin in the self, becomes barely external to self, and is self-monitored. Thus, in children both the configurations and the vocalizations associated with map reading have the properties of "self=objects" (Kohut, 1971). From the author's observation the delight which some children take in sounding out geographic names on a map may, in some instances, indicate pre-existing gratifying sound associations. Childish amusement in punning on cognomens may be an even greater stimulant for learning than visual configurations or artificial cognitive devices.

Auditory Perception↗

Selection of a Borrelia burgdorferi antigenic variant by cultivation in the presence of increasing amounts of homologous immune serum.

This investigation was undertaken to select antigenic variants of a Borrelia burgdorferi strain in vitro. The original strain BITS was cultivated in BSK medium supplemented with increasing concentrations of homologous hyperimmune serum raised in rabbits. After a few serial passages starting from a subinhibitory serum dilution of 1:800 in BSK up to 1:200, a variant named BITSv was obtained; it grew abundantly like the control culture in the presence of hyperimmune serum. Analysis of the antigenic pattern of the original and derived variants by Western blotting revealed that BITSv, compared to the original strain BITS, had lost the reactivity with the immune serum at the level of the oligosaccharide moiety. These experiments, designed to mimic the possible action of antibodies that arise during a Borrelia infection, suggest that lipopolysaccharides are surface located and that they play a role in the integrity of the outer membrane during the multiplication of Borrelia burgdorferi.

Antibodies, Bacterial↗

A novel method of time series analysis, and an application to the study of human sleep electroencephalogram.

A new mathematical method was developed to analyze time series. Applications of this method to the delta component of all-night sleep electroencephalogram (EEG) revealed new variations with double-rapid eye movement (REM)-sleep interval. The proposed method entails repeated application of the least squares spectrum. First, the conventional least squares spectrum calculation is applied to the time series. Using the parameters of the peak components in the obtained spectrum, an intermediate time series is reconstructed. The residual time series is made by subtracting the intermediate time series from the previous time series. Next, the least squares calculation is again applied to the residual time series. These procedures are repeated until the component cannot be detected. We named this new method the Repeated Least Squares Spectrum for the Residual (RLSSR). The remarkably similar time series pattern to the original time series can be reconstructed using the obtained parameters of all components. The EEG was recorded during all-night sleep on five consecutive nights in five healthy adults, by a total of 25 recordings. The variations of the height of successive 1-min delta components in the EEG were analyzed. In addition, two autocorrelograms were made for two time series patterns. These were reconstructed from two specific sets of the components obtained by the proposed analysis method. These autocorrelograms demonstrated a long-span variation with near double-REM-sleep interval in not a few records. Based on these data, it appears that the delta component of sleep EEG does not always demonstrate a simple gradually decreasing trend.

Adult↗

Similarity of the structure of DNA from a variety of sources.

DNA's from diverse cells of different species and from diverse tissues give the same x-ray diffraction pattern. The presently observable structure of DNA appears, then, to be the same in all cells. Thus, DNA in the resting state-the stored genetic material, from sperm of Paracentrotus lividus, Arbacia lixula, and salmon and from T(2) and T(7) bacteriophage-gives a pattern indistinguishable from DNA from very rapidly dividing cells, e.g., human acute leukemic leukocytes, human leukemic myeloid cells, mouse sarcoma 180, and bacteria-E. coli and pneumococci-during their logarithmic growth. The same x-ray patterns are given by DNA's from more slowly dividing tissues, e.g. calf liver, calf thymus, and human normal and leukemic lymphatic tissue. DNA from chicken erythrocytes-a DNA presumably metabolically inert-gives a similar picture. DNA's from several sources with a wide range in nitrogen base ratios, prepared independently by different workers using various methods, have given final products in varying yield; these all gave the same x-ray pattern, suggesting that all DNA is in the double-helical configuration. Finally, separation of the DNA molecule into a number of fractions with a varying adenine + thymine:guanine + cytosine ratio, but a constant adenine:thymine and guanine:cytosine ratio, each giving the same x-ray pattern as the original whole molecule, suggests that DNA cannot exist in significant amounts in forms other than the double-helix. X-ray diffraction photographs of sperm heads, extracted nucleoprotamine, calf thymus nuclei and extracted nucleohistone, and of chicken erythrocyte nuclei, are not all as well defined as those given by extracted DNA, but it is clear from the general characteristics of the pattern that much of the DNA bound to protein in these nuclei has the usual helical configuration, and that the double-helical structure of DNA exists in the cell and is not an artifact.

Adenine↗

[Biochemistry of brain lipids (especially fatty acids). In situ synthesis and exogenous origin during development. Various aspects of nutritional effects].

In contrast with other tissues, the nervous system is very rich in lipids, most of which are found in membranes. Fatty acids thus play a role in membrane structure and function: sphingolipids are essentially found in myelin and present original fatty acid patterns. Saturated and monounsaturated fatty acids are synthesized in microsomes by 3 different systems which differ at the level of the condensing enzyme. The activities of these systems are directly related to myelination. Mitochondria are also able to synthesize fatty acids but the pathways are totally different and unrelated to myelination. Moreover, the brain does not elaborate all its membrane fatty acids whose exogenous origin is demonstrated by injecting labelled non-essential fatty acids. The relationship between blood and brain vary during brain development; the uptake of fatty acids is quantitatively very important during glial cell multiplication and myelination. Nutrition alters the fatty acid composition of brain membranes; the fatty acids are largely altered in an opposite way in the neurons and oligodendrocytes of hypotrophic animals.

Animals↗

Characterization of an animal model of metastatic colon carcinoma.

Although numerous animal tumor models have been used to study colon carcinoma, few display metastatic properties. We have characterized an animal tumor model that has 3 properties essential for the study of metastasis of colon carcinoma cells: epithelial cell origin; a reproducible pattern of metastatic behavior and the ability to be propagated both in vitro and in vivo to facilitate identification of biochemical correlates of metastasis. The K12/TR cell line was derived from a transplantable colon carcinoma induced by dimethylhydrazine in the BD-1X rat strain. Transmission electron microscopy of K12/TR cells demonstrated junctional complexes, desmosomes and surface microvilli characteristic of gastrointestinal epithelial cells. The epithelial cell origin of K12/TR was confirmed by demonstrating the presence of keratin, a marker of epithelial cells, but not vimentin, a constituent of mesenchymal cells. Secretion of CEA and Ca19-9 antigens by K12/TR cells in vitro was below the sensitivity of the assays (1 ng/ml and 6 U/ml respectively). K12/TR cells produced tumors following s.c. injection into syngeneic BD-1X rats, allogeneic RNU/rnuDF rats and xenogeneic CRL:nu/nuBR mice. Macroscopic lung metastases were observed in animals from all 3 groups. Distal lymph node metastases were more frequent in BD-1X rats than in nude rats or mice. The histological appearances of all tumors and metastases were similar, showing a moderate to poorly differentiated glandular carcinoma. Intrasplenic injections of K12/TR cells in nude mice resulted in liver colonization. Preferential growth of tumor cells at sites of trauma was also observed. The results show that the K12/TR system can be used as a model to study metastasis of colon carcinoma cells and may find utility in the testing of chemotherapeutic agents against metastatic lesions.

Animals↗

Origination and innovation in the vertebrate limb skeleton: an epigenetic perspective.

The vertebrate limb has provided evolutionary and developmental biologists with grist for theory and experiment for at least a century. Its most salient features are its pattern of discrete skeletal elements, the general proximodistal increase in element number as development proceeds, and the individualization of size and shape of the elements in line with functional requirements. Despite increased knowledge of molecular changes during limb development, however, the mechanisms for origination and innovation of the vertebrate limb pattern are still uncertain. We suggest that the bauplan of the limb is based on an interplay of genetic and epigenetic processes; in particular, the self-organizing properties of precartilage mesenchymal tissue are proposed to provide the basis for its ability to generate regularly spaced nodules and rods of cartilage. We provide an experimentally based "core" set of cellular and molecular processes in limb mesenchyme that, under realistic conditions, exhibit the requisite self-organizing behavior for pattern origination. We describe simulations that show that under limb bud-like geometries the core mechanism gives rise to skeletons with authentic proximodistal spatiotemporal organization. Finally, we propose that evolution refines skeletal templates generated by this process by mobilizing accessory molecular and biomechanical regulatory processes to shape the developing limb and its individual elements. Morphological innovation may take place when such modulatory processes exceed a threshold defined by the dynamics of the skeletogenic system and elements are added or lost.

Animals↗

Multiple variations of the hepatobiliary vasculature including double cystic arteries, accessory left hepatic artery and hepatosplenic trunk: a case report.

Anatomical variations in the origins and branching patterns of the hepatobiliary arterial system may be encountered during both conventional surgical and laparoscopic cholecystectomy. We report a rare case of double cystic arteries arising from both the right hepatic artery and the proximal part of the posterior superior pancreaticoduodenal artery. Additional variations consisting of an accessory left hepatic artery arising from a left gastric which in turn arose from the descending aorta superior to the origin of the celiac trunk and a small left hepatic artery arising from the hepatic proper artery were also noted. The celiac trunk bifurcated into the splenic artery and the common hepatic artery forming a hepatosplenic or lienohepatic trunk. The possible clinical implications are discussed.

Cadaver↗

Different pattern of chromosomal allele loss in multiple hepatocellular carcinomas as evidence of their multifocal origin.

One of the most problematic aspects of surgery for hepatocellular carcinoma (HCC) is the frequent development of multiple tumors. Determination of the origin of multiple tumors, i.e., multifocal or metastatic, is important for predicting the clinical course of the disease after surgery. In order to clarify the origin of multiple tumors of HCC genetically, we examined patterns of loss of heterozygosity (LOH) on chromosome 16 for DNA isolated from 43 HCCs resected from 19 patients by analysis of restriction fragment length polymorphism. The cases were classified macro- and microscopically into 3 groups: multifocal origin; metastatic origin; and undetermined. Classification based on morphological features was shown to be well correlated with patterns of LOH in multiple tumors of HCC. Different patterns of LOH on chromosome 16 were detected in 8 of 11 patients with tumors of morphologically multifocal origin, whereas they were detected in none of 5 patients with tumors of morphologically metastatic origin. Among five patients with tumors of morphologically undetermined origin, a difference of LOH pattern among the tumors was detected in two, whereas in the other three, the pattern was identical between the tumors. A different pattern of LOH among HCCs arising in situ showed that they were composed of different clones, strongly suggesting their independent clonal origin and multifocal development. These results show that not only appropriate morphological observation but also examination of the LOH pattern on a particular chromosome is useful in diagnosis of multifocal HCC.

Alleles↗

Non-linearities in the focal ERG evoked by pattern and uniform-field stimulation. Their variation in retinal and optic nerve dysfunction.

The amplitude of the second harmonic of the focal electroretinogram (ERG) in response to either modulation of the luminance of the uniform-field or the spatial contrast of a patterned field (pattern-reversal ERG) was measured in a group of normal subjects as well as in patients with two different types of unilateral dysfunctions, namely optic atrophy or temporary retinal ischemia. Such patients had a reduced visual acuity in their affected eyes but normal full-field flicker (20 Hz) ERG. In normal eyes, for the same stimulation area and modulation depth, the second harmonic of the uniform-field response is smaller (mean value 62%) than that of the optimal pattern (around 1.5 cycles/degree). The results on patients show that the second harmonic of the pattern response, but not that of the uniform-field response, is reduced in cases of optic atrophy secondary to trauma or optic neuritis. This result suggests generators different, at least in part, for the second harmonic evoked by modulation of either luminance or spatial contrast. By contrast, both responses are reduced in cases of temporary retinal ischemia. These findings are discussed in light of the recent literature on the origin of the pattern ERG. The possible clinical applications of the technique are outlined.

Adolescent↗

Identification and expansion of human colon-cancer-initiating cells.

Colon carcinoma is the second most common cause of death from cancer. The isolation and characterization of tumorigenic colon cancer cells may help to devise novel diagnostic and therapeutic procedures. Although there is increasing evidence that a rare population of undifferentiated cells is responsible for tumour formation and maintenance, this has not been explored for colorectal cancer. Here, we show that tumorigenic cells in colon cancer are included in the high-density CD133+ population, which accounts for about 2.5% of the tumour cells. Subcutaneous injection of colon cancer CD133+ cells readily reproduced the original tumour in immunodeficient mice, whereas CD133- cells did not form tumours. Such tumours were serially transplanted for several generations, in each of which we observed progressively faster tumour growth without significant phenotypic alterations. Unlike CD133- cells, CD133+ colon cancer cells grew exponentially for more than one year in vitro as undifferentiated tumour spheres in serum-free medium, maintaining the ability to engraft and reproduce the same morphological and antigenic pattern of the original tumour. We conclude that colorectal cancer is created and propagated by a small number of undifferentiated tumorigenic CD133+ cells, which should therefore be the target of future therapies.

AC133 Antigen↗

Molecular analysis of cases of Italian sheep scrapie and comparison with cases of bovine spongiform encephalopathy (BSE) and experimental BSE in sheep.

Concerns have been raised about the possibility that the bovine spongiform encephalopathy (BSE) agent could have been transmitted to sheep populations via contaminated feedstuffs. The objective of our study was to investigate the suitability of molecular strain typing methods as a surveillance tool for studying scrapie strain variations and for differentiating PrP(Sc) from sheep scrapie, BSE, and sheep BSE. We studied 38 Italian sheep scrapie cases from 13 outbreaks, along with a British scrapie case, an experimental ovine BSE, and 3 BSE cases, by analyzing the glycoform patterns and the apparent molecular masses of the nonglycosylated forms of semipurified, proteinase-treated PrP(Sc). Both criteria were able to clearly differentiate sheep scrapie from BSE and ovine experimental BSE. PrP(Sc) from BSE and sheep BSE showed a higher glycoform ratio and a lower molecular mass of the nonglycosylated form compared to scrapie PrP(Sc). Scrapie cases displayed homogeneous PrP(Sc) features regardless of breed, flock, and geographic origin. The glycoform patterns observed varied with the antibody used, but either a monoclonal antibody (MAb) (F99/97.6.1) or a polyclonal antibody (P7-7) was able to distinguish scrapie from BSE PrP(Sc). While more extensive surveys are needed to further corroborate these findings, our results suggest that large-scale molecular screening of sheep populations for BSE surveillance may be eventually possible.

Animals↗

Vascular casts of experimental subretinal neovascularization in monkeys.

The origin, course, and pattern of experimental subretinal neovascularization (SRN) in monkeys were studied with scanning electron microscopy (SEM) of Mercox preparations of the choroidal vascular bed. This technique allowed visualization of the entire circulation of the SRN lesion from both the retinal and scleral aspects. The SEM data is comparable to that of fluorescein angiography, but provides details not detectable by angiography. The afferent arteriole was traced back to the posterior ciliary artery of origin. In the early stages, the efferent vessels appeared to connect with the choriocapillaris; whereas later the efferent vessels connected directly to the choroidal venous system. The study of such plastic casts enables more accurate assessment of some aspects of the vascular architecture of the SRN frond.

Animals↗

Analysis of polymorphic variation in drug metabolism: II. Effects of data transformation on the sensitivity and specificity of modal detection.

Simulations were conducted for a model of drug metabolism involving 2 parallel competing pathways of elimination, wherein the effects of variability in 1 enzyme pathway were examined with respect to variability in recovery of its metabolite and recovery of metabolite through the second, nonvaried, co-eliminating route. Expression of metabolite recoveries as fractions of the total recoverable drug yielded a statistic possessing variability similar to the pattern of variability induced in the enzyme itself. However, the transformation was subject to a "distributive" effect, in that the magnitude of variation in the downstream metabolite was reduced and transferred through reciprocal variations in availability of unmetabolized drug to other nonvaried pathways. The sensitivity and specificity of the fractional recovery statistic were thereby diminished. Expression of recoveries as metabolic ratios, on the other hand, limited variability to the pathway in which it was originally induced. The pattern of variation was skewed and exaggerated, particularly towards the rightward, "poor metabolizer" tail of the distribution, and this caused problems with visual interpretations as well as more objective approaches like the kernel density estimate. Additional transformation to the log metabolic ratio provided considerable improvement in this regard. Thus, log metabolic ratios are the most sensitive and specific of the data transformations and are the preferred manner of expression in all multipathway metabolite analyses.

Biotransformation↗

Time distribution of the recurrence risk for breast cancer patients undergoing mastectomy: further support about the concept of tumor dormancy.

PURPOSE: To gather information on metastatic growth from the time-distribution of first treatment failure in breast cancer patients undergoing mastectomy alone. METHODS: The risk of recurrence at a given time after surgery was studied utilizing the cause-specific hazard function. Recurrence was categorized as first treatment failure at any site, local-regional recurrence, distant metastases, and contralateral tumor. The risk distribution was assessed relative to tumor size, axillary lymph node involvement, and menopausal status. RESULTS: A total of 1173 patients treated between 1964 and 1980 with mastectomy alone and no adjuvant therapy were studied. The hazard function for first failure presented an early peak at about 18 months after surgery, a second peak at about 60 months and then a tapered plateau-like tail extending up to 15 years. A similar risk pattern was detectable for both local recurrence and distant metastases, while the curve of contralateral breast tumors showed a near flat plateau. The risk of early local-regional and distant recurrences was much lower for tumors less than 2 cm in diameter than for larger tumors; the risk of late recurrence was similar for small and large primaries. Node-positive patients showed peaks four to five times higher than node-negative patients. Sub-dividing node-positive patients into 1-3 and > 3 node-positive subsets did not substantially change the general picture of tumor recurrence. The hazard functions for premenopausal and postmenopausal patients were virtually superimposable. CONCLUSIONS: The multipeak hazard curve suggests that the process resulting in overt clinical metastases may have discrete features. Primary tumor size could affect in different ways early and late metastases, while axillary node status should be related to the risk level, not to the risk pattern, and menopausal status does not seem to significantly affect the hazard distribution. Moreover, contralateral breast tumors, occurring at constant risk throughout the time, should be considered as second primary cancers. These findings could be reasonably explained by a tumor dormancy hypothesis, which assumes that micrometastases may be in different biological steady states, most of which do not imply tumor growth. Tumor or microenvironment changes could induce metastatic growth after given mean transition times from surgery and originate a discrete pattern of the hazard function.

Adult↗

The epsilon-sarcoglycan gene (SGCE), mutated in myoclonus-dystonia syndrome, is maternally imprinted.

Myoclonus-dystonia syndrome (MDS) is a non-degenerative neurological disorder that has been described to be inherited in an autosomal dominant mode with incomplete penetrance. MDS is caused by loss of function mutations in the epsilon-sarcoglycan gene. Reinvestigation of MDS pedigrees provided evidence for a maternal imprinting mechanism. As differential methylated regions (DMRs) are a characteristic feature of imprinted genes, we studied the methylation pattern of CpG dinucleotides within the CpG island containing the promoter region and the first exon of the SGCE gene by bisulphite genomic sequencing. Our findings revealed that in peripheral blood leukocytes the maternal allele is methylated, while the paternal allele is unmethylated. We also showed that most likely the maternal allele is completely methylated in brain tissue. Furthermore, CpG dinucleotides in maternal and paternal uniparental disomy 7 (UPD7) lymphoblastoid cell lines show a corresponding parent-of-origin specific methylation pattern. The effect of differential methylation on the expression of the SGCE gene was tested in UPD7 cell lines with only a weak RT-PCR signal observed in matUPD7 and a strong signal in patUPD7. These results provide strong evidence for a maternal imprinting of the SGCE gene. The inheritance pattern in MDS families is in agreement with such an imprinting mechanism with the exception of a few cases. We investigated one affected female that inherited the mutated allele from her mother. Surprisingly, we found the paternal wild type allele expressed whereas the mutated maternal allele was not detectable in peripheral blood cDNA.

5-Methylcytosine↗

Rural implications of Medicare's post-acute-care transfer payment policy.

CONTEXT: Under the Medicare post-acute-care (PAC) transfer policy, acute-care hospitals are reimbursed under a per-diem formula whenever beneficiaries are discharged from selected diagnosis-related groups (DRGs) to a skilled nursing facility, home health care, or a prospective payment system (PPS)-excluded facility. Total per-diem payments are below the full DRG payment only when the patient's length of stay (LOS) is short relative to the geometric mean LOS for the DRG; otherwise, the full DRG payment is received. This policy originally applied to 10 DRGs beginning in fiscal year 1999 and was expanded to additional DRGs in FY2004. The Secretary may include other DRGs and types of PAC settings in future expansions. PURPOSE: This article examines how the initial policy change affected rural and urban hospitals and investigates the likely impact of the FY2004 expansion and other possible future expansions. METHODS: The authors used 1998-2001 Medicare Provider Analysis and Review (MEDPAR) data to investigate changes in hospital discharge patterns after the original policy was implemented, compute the change in Medicare revenue resulting from the payment change, and simulate the expected revenue reductions under expansions to additional DRGs and swing-bed discharges. FINDINGS: Neither rural nor urban hospitals appear to have made a sustained change in their discharge behavior so as to limit their exposure to the transfer policy. Financial impacts from the initial policy were similar in relative terms for both types of hospitals and would be expected to be fairly similar for an expansion to additional DRGs. On average, including swing-bed discharges in the transfer policy would have a very small financial impact on small rural hospitals; only hospitals that make extensive use of swing beds after a short inpatient stay might expect large declines in total Medicare revenue. CONCLUSION: Rural hospitals are not disproportionately harmed by the PAC transfer policy. An expanded policy may even benefit rural hospitals by recognizing their lower use of post-acute-care and readjusting DRG weights so that they are paid more appropriately when providing the full course of inpatient care.

Aftercare↗

A single amphioxus and sea urchin runt-gene suggests that runt-gene duplications occurred in early chordate evolution.

Runt-homologous molecules are characterized by their DNA binding runt-domain which is highly conserved within bilaterians. The three mammalian runt-genes are master regulators in cartilage/bone formation and hematopoiesis. Historically these features evolved in Craniota and might have been promoted by runt-gene duplication events. The purpose of this study was therefore to investigate how many runt-genes exist in the stem species of chordates, by analyzing the number of runt-genes in what is likely to be the closest living relative of Craniota-amphioxus. To acquire further insight into the possible role of runt-genes in early chordate evolution we have determined the number of runt-genes in sea urchins and have analyzed the runt-expression pattern in this species. Our findings demonstrate the presence of a single runt-gene in amphioxus and sea urchin, which makes it highly likely that the stem species of chordates harbored only a single runt-gene. This suggests that runt-gene duplications occurred later in chordate phylogeny, and are possibly also associated with the evolution of features such as hematopoiesis, cartilage and bone development. In sea urchin embryos runt-expression involves cells of endodermal, mesodermal and ectodermal origin. This complex pattern of expression might reflect the multiple roles played by runt-genes in mammals. A strong runt-signal in the gastrointestinal tract of the sea urchin is in line with runt-expression in the intestine of nematodes and in the murine gastrointestinal tract, and seems to be one of the phylogenetically ancient runt-expression domains.

Amino Acid Sequence↗