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Results for “multiple clustering”

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At least 235 records · Page 13Linked to original sources
PubMed1999

Granulomatous mastitis: mammographic and sonographic appearances.

OBJECTIVE: The objective of our study is to describe the mammographic and sonographic appearances of granulomatous mastitis. CONCLUSION: Granulomatous mastitis can mimic breast carcinoma clinically and mammographically, but the sonographic appearance of multiple clustered, often contiguous tubular hypoechoic lesions that are sometimes associated with a large hypoechoic mass should suggest the possibility of granulomatous mastitis.

Adult↗
PubMed1993

Multiple transcription start sites in the rat insulin-like growth factor-I gene give rise to IGF-I mRNAs that encode different IGF-I precursors and are processed differently in vitro.

Two distinct class 1 and class 2 rat liver IGF-I mRNAs contain different 5' leader exons, 1 and 2. RNase protection, primer extension, RACE PCR and ribonuclease H mapping established the complete structure of the 5' end of class 1 and class 2 IGF-I mRNAs. Two major transcription start sites in exon 1 yield class 1 IGF-I mRNAs, including 345 or 245 bases of exon 1. Multiple, clustered transcription start sites in exon 2 yield class 2 IGF-I mRNAs with 84-50 bases of exon 2. Cell-free translation of in vitro transcribed IGF-I mRNAs suggests that class 1 and class 2 mRNAs preferentially initiate translation at distinct AUG codons to result in IGF-I precursors with either 48 residue class 1 pre-peptides or 32 residue class 2 pre-peptides. Some translation initiation also occurs at a downstream AUG common to class 1 and 2 mRNAs to yield IGF-I precursors with a 22 residue pre-peptide. Inclusion of microsomal membranes in translations suggests that the three different pre-peptides each function as co-translationally cleaved signal peptides. However, treatment of processed precursors with endoglycosidase H indicates that co-translational processing of precursors with 22 and 32 residue pre-peptides leads to glycosylation of downstream IGF-I precursor sequences whereas co-translational processing of precursors with 48 residue pre-peptide is not associated with glycosylation.

Animals↗
PubMed2005

[Prevalence rate and factors of myopia in preschool children].

PURPOSE: This study was aimed at providing basic data for developing a nursing intervention program which enables systematic and correct visual acuity care by discovering out visual acuity conditions, prevalence rate of myopia, and the factors related to myopia with Preschool children. METHOD: The subjects of this study consisted of 519 children between 3 and 6 years of age from 12 kindergartens in Seoul which were selected through multiple cluster sampling. Myopia was defined as the spherical equivalent (SE) of more than -0.5 diopters (D) in the right eye. The data was analyzed by t-test, chi(2)-test, ANOVA, and logistic regression by using the SAS program. RESULT: The prevalence rate of myopia was 8.7%. the odds ratio of child myopia when one parent had myopia was 2.2 times higher than when neither parent had myopia. The odds ratio of child myopia when reading more than three books per week was 0.27 times higher than reading less than three books. CONCLUSION: Myopia should be continuously and intensively managed from the age of 3.

Child↗
PubMed2000

Tumors arising in DNA mismatch repair-deficient mice show a wide variation in mutation frequency as assessed by a transgenic reporter gene.

We reported previously that thymic lymphomas arising in mice lacking the DNA mismatch repair (MMR) gene, Msh2(-/-), exhibited striking elevations in the mutation frequency of a transgenic lacI reporter gene when compared with normal Msh2(-/-) tissues. To investigate whether hypermutation was a feature of all tumors arising in MMR-deficient mice, lacI transgene mutation frequencies were obtained from several different mouse tumors deficient for PMS2 and/or MSH2. While lacI gene hypermutation was again clearly evident in Msh2 +/- ms2(-/-) and Msh2(-/-)Pms2(-/-) thymic lymphomas, three non-thymic MSH2-deficient tumors failed to show lacI gene mutation frequency elevations when compared with a normal tissue of MMR-deficient mice. The elevated mutation frequencies in the lymphoid tumors, and the finding of multiple clustered mutations in lacI genes rescued from these tumors, suggest that they are possibly generated by a lymphoma-specific hypermutational mechanism.

Animals↗
PubMed1999

Visual phenomena and headache in occipital epilepsy: a review, a systematic study and differentiation from migraine.

This is a systematic-prospective study of occipital seizures with elementary visual hallucinations in 18 patients with symptomatic occipital epilepsy. Qualitative and chronological analysis showed that visual seizures usually lasted for seconds to 1-3 minutes. Three patients also had longer visual seizures of 20-150 minutes. Elementary visual hallucinations mainly consisted of coloured and small circular patterns flashing or multiplying in a temporal hemifield. Flashing lights or non-circular patterns were rare. Three patients experienced achromatic flickering lights. None of the patients had the over 4 minute, linear, zigzag, and achromatic or black and white patterns characteristic of migraine visual aura. Blurring of vision could precede visual hallucinations. Visual seizures were usually frequent, often occurring in multiple clusters daily or weekly. They usually occurred alone but they often advanced to other occipital and extra-occipital ictal symptoms. In 7 patients they progressed to temporal lobe seizure manifestations, and in 6 to motor partial seizures or ipsilateral hemiconvulsions. All but 2 had secondary generalised tonic clonic convulsions. Ictal blindness ab initio occurred in 2 and ictal, mainly orbital headache in another 2 patients. One patient had ictal vomiting as an occasional symptom. Postictal headache, often severe and indistinguishable from migraine, occurred in two thirds of the patients, even after brief visual seizures without convulsions. Despite relevant structural lesions in brain imaging, 10 patients had a normal mental and neurological state. In 8 patients, EEG was also normal or nonspecific. Misdiagnosis of visual seizures as visual aura of migraine was common and 3 patients were misdiagnosed as suffering from migraine. The differential diagnosis between migraine and the occipital epilepsies is reviewed. It is concluded that elementary visual hallucinations, blindness or both, alone or followed by headache and vomiting of symptomatic occipital epilepsy are identical to those of idiopathic occipital epilepsy. Progress to temporal lobe structures is different and consistent with symptomatic occipital lobe epilepsy. The clinical diagnosis of visual seizures is easy if individual elements of duration, colour, shape, size, location, movement, speed of development and progress are identified. They are markedly different from visual aura of migraine, although they often trigger migrainous headache, probably by activating trigeminovascular or brain stem mechanisms.

Adolescent↗
PubMed1992

[Are disturbances of small intestinal motility associated with hyperglucagonemia in patients with liver cirrhosis?].

Patients with liver cirrhosis develop marked abnormalities in small bowel motility and high plasma glucagon levels. Disturbances in small intestinal motor activity could be related to hyperglucagonemia. To investigate the relationship between fasting plasma glucagon levels and changes in small bowel motility in patients with liver cirrhosis, eighteen cirrhotic patients and ten controls were studied. Plasma glucagon was measured by RIA. Mouth to cecum transit time was estimated by lactulose hydrogen breath test. Fasting small bowel motility was investigated by means of intraluminal manometry. Plasma glucagon levels were significantly higher in patients with cirrhosis (61 +/- 5 pmol/l) than in controls (32 +/- 3 pmol/l); p < 0.01. In patients with liver disease, plasma glucagon levels were not significantly correlated to mouth to cecum transit time (r: -0.32), duration of migrating motor complex (r: -0.24), nor to the frequency of multiple clustered contractions (r: -0.26). The degree of small bowel dysmotility is not related to plasma glucagon levels in patients with hepatic cirrhosis. These results do not support the hypothesis that hyperglucagonemia plays an important pathogenic role in the abnormalities of gut motility in cirrhosis.

Adult↗
PubMed1992

Structure and function of murine TIMP gene.

Specific inhibitors of metalloproteinases, such as TIMP, are potential regulators of tissue integrity. In order to understand their exact role in both normal and pathological processes we have initiated molecular studies on the TIMP gene and its product(s). We have used cDNA and genomic clones corresponding to the murine TIMP gene to define the intron-exon structure of the gene and to map multiple clustered sites where transcription is initiated; we have also partially characterized the cis-acting DNA sequences required for transcriptional activity. The murine TIMP cDNA has also been used in transcription/translation experiments to produce polypeptides which can be processed by endoplasmic reticulum membranes and which are biochemically active in inhibition of fibroblast interstitial collagenase. As a result of our analysis of the expression of the TIMP gene in different cell types and under varied conditions, we have observed an important increase of TIMP mRNA levels in mouse fibroblasts in response to physiological modulators (whole serum and double-stranded RNA) as well as a pathogen (NewCastle Disease Virus). In addition, an analysis of TIMP mRNA in several variants of a cell line derived from a spontaneous mammary adenocarcinoma, which possess different levels of metastatic potential indicated that the serum dependence of TIMP mRNA accumulation is different in metastatic as compared to nonmetastatic cells. The significance of these results in view of the role of TIMP in matrix maintenance is discussed.

Adenocarcinoma↗
PubMed1986

Transcription at bacteriophage T4 variant late promoters. An application of a newly devised promoter-mapping method involving RNA chain retraction.

Bacteriophage T4 late promoters display a conserved sequence that extends over about 18 base pairs, in which the central 8-base pair sequence (TATAAATA in the nontranscribed strand) is absolutely conserved. Transcription by T4-modified RNA polymerase in vitro nevertheless initiates within a cluster of 6 overlapping variant T4 late promoters that deviate from the absolutely conserved sequence at one or two positions. One of these variant promoters is dominant, and its sequence implies that two of the absolutely conserved nucleotides (underlined above) are not essential. Three other variant promoters that contain only one of the deviations found in the dominant variant promoter are, at best, utilized weakly, suggesting that sequences outside the absolutely conserved segment are important for promoter function. A newly devised method, based on arrest of RNA chain elongation with ribonucleotide analogs and its reversal, has been used to precisely map initiation within the overlapping promoter cluster. Multiple cycles of RNA chain arrest, pyrophosphorolysis, and resynthesis can be executed. This process permits a precise stepwise control of the advance of a transcription complex through a gene.

Base Sequence↗
PubMed1985

Molecular cloning and DNA sequence analysis of genes encoding cytotoxic T lymphocyte-defined HLA-A3 subtypes: the E1 subtype.

Influenza-specific cytotoxic T cells restricted by HLA-A3 and allogeneic CTL specific for HLA-A3 recognize differences between serologically indistinguishable HLA-A3 antigens. Previous biochemical studies have indicated that such differential recognition can be explained by alterations in the primary structure of class I heavy chains. Characterization of these sequence differences may therefore identify portions of the class I molecule that form determinants recognized by CTL. In this study, we describe the cloning and sequencing of an HLA-A3 subtype from donor E1 (E1-A3). Cloning of the gene encoding E1-A3 was simplified by determining that a 15.5-kb BamHI fragment contains the complete gene and is characteristic of HLA-A3 and only one other class I gene (HLA-A11). Comparison of the E1-A3 sequence to that of a previously sequenced HLA-A3 gene for exons encoding extracellular class I domains revealed three nucleotide differences. All of these differences were located within a discrete region of exon 3 (encoding the alpha 2 domain) and result in a change of two amino acids, at positions 152 (Glu----Val) and 156 (Leu----Gln). This finding suggests that these amino acids are crucial for the information of a determinant recognized by CTL. Furthermore, the altered nucleotide sequence of E1-A3 is identical to the sequence of the HLA-Aw24 gene for codons 128 to 161. These observations of multiple clustered changes in the E1-A3 subtype (relative to the prototype sequence) and identity of the altered sequence with the sequence of another class I gene support the concept that gene conversion is a primary mechanism for the generation of class I polymorphism.

Adult↗
PubMed1993

Phosphorylation weakens DNA binding by peptides containing multiple "SPKK" sequences.

Sea urchin testis-specific H1 and H2B histones (Sp H1 and Sp H2B) are characterized by reversibly phosphorylated N-terminal regions consisting largely of multiple clustered "SPKK" tetrapeptides (serine-proline adjacent to two basic amino acids). This report presents data showing differences in DNA affinities between peptides containing dephosphorylated and phosphorylated N-terminal regions. Sp H1 and its phosphorylated derivative (pSp H1) were purified by hydroxylapatite chromatography. Peptides containing the N-terminal regions of Sp H1 and pSp H1 (NP and pNP, respectively) were produced by digestion with Staphylococcus aureus protease. NP and two forms of pNP differing in phosphate content were purified by DNA-cellulose chromatography. The DNA affinities of the peptides were compared using several criteria. NP was bound more tightly by DNA-cellulose than pNPs. NP precipitated DNA under a broad range of NaCl concentrations; pNPs did not. Both NP and pNPs protected DNA against thermal denaturation, but NP created a more stable DNA-peptide complex. Thirty to sixty times more pNP than NP was required to obtain equivalent inhibition of Hoechst 33258 binding to DNA. NP did not behave as a competitive inhibitor of DNA binding by Hoechst 33258 binding to DNA. We conclude that during spermatogenesis, dephosphorylation of the Sp H1 N-terminal region increases its basicity and thus its affinity for DNA.

Amino Acid Sequence↗
PubMed1994

Microcalcifications associated with ductal carcinoma in situ: mammographic-pathologic correlation.

Because of the large scale use of mammography, the incidence of ductal carcinoma in situ (DCIS) has been increased fivefold to sixfold. The majority of these tumors are detected by mammographically significant microcalcifications. Their mammographic and histologic appearance is rather characteristic for the different types of DCIS. Microcalcifications associated with poorly differentiated DCIS appear on the mammogram as either linear, often branching, or as granular microcalcifications which are usually coarse. They correspond to the amorphous type calcifications on histology. Microcalcifications associated with well-differentiated DCIS appear on the mammogram usually as multiple clusters of fine granular microcalcifications, which correspond to the clusters of laminated, crystalline calcifications on histology. The distribution of DCIS is typically unicentric and segmental. In a series of 119 mastectomies, only a single case had a multicentric distribution. Based on the extent of microcalcifications, mammography usually underestimates the size of DCIS; although this discrepancy is less than 2 cm in 80% to 85% of the cases if state-of-the-art mammography, including magnification views, is used. Close co-operation between radiologist, pathologist, and surgeon is essential for the optimum management of patients with DCIS.

Breast Neoplasms↗
PubMedDate not supplied

Combined adenovirus and rotavirus enteritis with Escherichia coli septicemia in an emu chick (Dromaius novaehollandiae).

A 2-week-old emu chick (Dromaius novaehollandiae) of approximately 200 g body weight was presented for necropsy with a history of weakness, diarrhea, pallor of the head, and acute death. Hemorrhagic enteritis with mild hepatomegaly was noted on gross examination. Microscopic examination revealed necrohemorrhagic enteritis with intralesional intranuclear basophilic viral inclusion bodies in intestinal epithelial cells; splenic lymphoid necrosis and fibrin exudation; hepatocellular vacuolar change; and multiple clusters of small gram-negative bacilli in the liver, spleen, yolk sac, and intestine. Transmission electron microscopy of negatively stained fecal specimens and thin sections of small intestine revealed clusters of viral particles consistent with adenovirus and rotavirus. Attempts at viral isolation from pooled tissue specimens were unsuccessful. Escherichia coli was isolated from specimens of liver and intestine and from an abdominal swab.

Adenoviridae Infections↗
PubMed1996

Ig light chain gene in the Siberian sturgeon (Acipenser baeri).

Elasmobranch and teleost fish have their Ig light (L) chain loci organized in multiple clusters (VL-JL-CL). The VL segments of teleosts are in opposite transcriptional orientation to the CL genes, suggesting that in teleosts and elasmobranchs there may have been separate evolutionary events leading to this organization. To address this problem, the IgL locus from the Siberian sturgeon (Acipenser baeri) (representative of a branch between elasmobranchs and teleosts) was investigated. Sequence analysis of cDNA clones shows that sturgeon VL genes are most similar to those of teleosts, but that sturgeon CL genes are more similar to those of the sharks. Southern blot analyses of sturgeon erythrocyte DNA with VL- and CL-specific probes showed that there are more than 20 VL segments in both the tetraploid Siberian sturgeon and the diploid sterlet (Acipenser ruthenus), but only a few CL segments in the genome of the Siberian sturgeon and up to four CL segments in that of the sterlet. Screening of an unamplified genomic library gave more than 300 VL-positive and four CL-positive clones. None of these contained inserts positive for both probes. PCR analysis of a genomic CL clone using IC and CL-specific primers suggested that upstream of the CL segment there are at least seven JL segments. it is concluded that sturgeons have a kappa-like organization of their IgL locus and that the clustered organization of IgL loci in bony fish and sharks arose from two distinct evolutionary events.

Amino Acid Sequence↗
PubMed1996

Methyltransferase-specific domains within VP-39, a bifunctional protein that participates in the modification of both mRNA ends.

VP39 is a bifunctional vaccinia virus protein that acts as both a cap- dependent 2'-O-Methyltransferase and a poly(A) polymerase processivity factor. An analysis of C-terminal truncation mutants of a GST-VP39 fusion protein indicated the presence of a protease-sensitive C-terminal "tail" 36-43 amino acids in length that is non-essential for VP39 function. Fourteen new VP39 pointmutants, containing either single or multiple-clustered amino acid substitutions, were expressed in Escherichia coli. Of the eight that retained either one or both of the activities of VP39, seven were specifically methyltransferase-defective. None was specifically defective in adenylyltransferase stimulation. The nature of the methyltransferase defects in 10 of the methyltransferase-specific defectives, identified both herein and in a previous study (Schnierle BS, Gershon PD, Moss B, 1994, J biol Chem 269:20700-20706), was investigated using two novel substrate-binding assays. Three of the mutants (and possible a fourth), whose lesions were juxtaposed and centrally located within VP39, exhibited anomalous S-adenosyl-(L)-methionine (AdoMet) binding behavior, identifying residues important for AdoMet binding and possible also for catalysis. A surface plasmon resonance-based assay measured the interaction of VP39 with uncapped and 5'-cap 0-terminated oligo(A). A cap 0- dependent association-rate enhancement was observed for wild-type VP39 and 4 of the 10 mutant proteins. Two others were identified as defective in cap binding, and a third as partially defective. The lesions within the latter three mutants were closely apposed, and located toward the N-terminus of VP39. We have thus identified regions of VP39 important for interaction with its two substrates for cap-dependent methyltransferase activity: AdoMet and cap 0.

Amino Acid Sequence↗
PubMed1997

Identification of caveolin and caveolin-related proteins in the brain.

Caveolae are 50-100 nm, nonclathrin-coated, flask-shaped plasma membrane microdomains that have been identified in most mammalian cell types, except lymphocytes and neurons. To date, multiple functions have been ascribed to caveolae, including the compartmentalization of lipid and protein components that function in transmembrane signaling events, biosynthetic transport functions, endocytosis, potocytosis, and transcytosis. Caveolin, a 21-24 kDa integral membrane protein, is the principal structural component of caveolae. We have initiated studies to examine the relationship of detergent-insoluble complexes identified in astrocytes to the caveolin-caveolae compartment detected in cells of peripheral tissues. Immunolocalization studies performed in astrocytes reveal caveolin immunoreactivity in regions that correlate well to the distribution of caveolae and caveolin determined in other cell types, and electron microscopic studies reveal multiple clusters of flask-shaped invaginations aligned along the plasma membrane. Immunoblot analyses demonstrate that detergent-insoluble complexes isolated from astrocytes are composed of caveolin-1alpha, an identification verified by Northern blot analyses and by the cloning of a cDNA using reverse transcriptase-PCR amplification from total astrocyte RNA. Using a full-length caveolin-1 probe, Northern blot analyses suggest that the expression of caveolin-1 may be regulated during brain development. Immunoblot analyses of detergent-insoluble complexes isolated from cerebral cortex and cerebellum identify two immunoreactive polypeptides with apparent molecular weight and isoelectric points appropriate for caveolin. The identification of caveolae microdomains and caveolin-1 in astrocytes and brain, as well as the apparent regulation of caveolin-1 expression during brain development, identifies a cell compartment not detected previously in brain.

Animals↗
PubMed1976

A test for randomness.

A procedure is proposed for studying the hypothesis that a sequence of dichotomous random variables are independent and identically (randomly) distributed. The procedure is relatively sensitive to departures from randomness involving multiple clustering. An application to testing for Schwann cell disease is discussed. The distrubution of the sample coefficient of variation from an exponential distribution, a useful statistic in testing randomness for a continuous model, is also studied.

Biometry↗
PubMed1998

Anatomic evidence of a three-dimensional mosaic pattern of tonotopic organization in the ventral complex of the lateral lemniscus in cat.

The ventral complex of the lateral lemniscus (VCLL, i.e., the ventral and intermediate nuclei) is composed of cells embedded in the fibers of the lateral lemniscus. These cells are involved in the processing of monaural information and receive input from the collaterals of the fibers ascending to the inferior colliculus. Whereas tonotopic organization is a feature of all other nuclei of the auditory system, this functional principle is debated in the VCLL. We have made focal injections of the tracer biotinylated dextran amine into different frequency band representations of the inferior colliculus in cat. Retrogradely labeled cells and terminal fibers (collaterals of efferent local axons and other ascending lemniscal fibers) were found in the ipsilateral VCLL. The spatial distribution of the labeling was analyzed using three-dimensional (3-D) reconstruction and computer graphical visualization techniques. A complex topographic organization was found. In all cases, labeled fibers and cells were distributed in multiple clusters throughout the dorsoventral extent of the VCLL. The shape, size, and location of the labeled clusters suggest an interdigitation of clusters assigned to different frequency-band representations. But an overall mediolateral distribution gradient was observed, with high frequencies represented medially and lower frequencies progressively more laterally. We conclude that the clusters may represent discontinuous frequency-band compartments as a counterpart to the continuous laminar compartments in the remaining auditory nuclei. The 3-D orderly mosaic pattern indicates that the VCLL preserves the spectral decomposition originated in the cochlea in a way that facilitates across-frequency integration.

Animals↗
PubMed2000

A test for spatial disease clustering adjusted for multiple testing.

Tango (1995) proposed a test statistic C for detecting spatial disease clusters. However, like most other methods, it requires a value of the scale parameter which adjusts for the size of cluster to be detected in advance of its use. When an appropriate size of cluster cannot be predicted and many clustered areas are expected, we usually repeat the procedure by changing the size parameter, but this practice clearly faces a multiple testing problem. In this paper, to ameliorate this problem, we propose an extended test statistic which searches the minimum of the profile P-value of C for the parameter on cluster size which varies continuously from a small value near zero upwards until it reaches to about half the size of the whole study area. Monte Carlo simulation study shows that the power of the proposed method is shown to be reasonably high compared with the best power attained by C unadjusted for multiple testing in all the cluster models considered. The proposed procedure is illustrated with some disease maps simulated in the Tokyo Metropolitan Area.

Humans↗