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PubMed1995

Chondrogenic potential of chick embryonic calvaria: I. Low calcium permits cartilage differentiation.

Calvaria from day-14 calcium-deficient chick embryos produced by long-term maintenance in shell-less culture, exhibit a cartilage-like phenotype (Jacenko and Tuan [1986] Dev. Biol. 115:215-232), which is restored to an osteogenic phenotype upon calcium repletion to the embryo. The expression of cartilage markers in a typically osteogenic tissue under calcium deficiency implies the presence of chondrogenic cells, and questions the conditions associated with calcium deficiency which may cause their divergent pathway of differentiation. In the present study, by explanting normal and shell-less embryonic calvarial pairs in organ culture in vitro and experimentally regulating their calcium supply, the calcium status of the calvaria was modulated as a function of medium calcium. Histological and immunoblotting analyses demonstrated for the first time that calvaria possess cells which can form genuine cartilage. This chondrogenic potential is expressed only in a low-calcium environment, where cartilage forms in both normal and shell-less calvarial pairs; their calcium-supplemented counterparts, however, develop as fully osteogenic tissues. Furthermore, chondrogenesis in both normal and shell-less calvaria indicates that the chondrogenic cells must be endogenous constituents of the calvaria, rather than being derived elsewhere in response to systemic calcium deficiency. Finally, the correlation between matrix under-calcification and cartilage expression in the embryonic calvarium suggests that calcium, perhaps in the form of matrix mineral, may modulate cell differentiation during skeletogenesis.

Animals↗

PubMedDate not supplied

Abnormal matrix recognition by Morris hepatomas correlates with low glucagon binding capacity.

Liver biomatrix contains a group of connective tissue components needed for attachment, survival, and maintenance of liver-specific functions of adult rat hepatocytes in culture. An acidic extract of liver biomatrix that contains a group of glycoproteins can replace intact biomatrix in promoting attachment and survival of hepatocytes. However, except for albumin synthesis, liver-specific functions have not been tested. Acidic extracts of biomatrices prepared from heart, kidney, lung, and spleen (heterologous) contain a similar group of glycoproteins, but differ with respect to liver glycoproteins in their capacity to sustain hepatocyte binding. Normal hepatocytes attach poorly to heterologous glycoprotein extracts, although regenerating and tumoral hepatocytes attach to liver glycoproteins and adhere equally well or with greater efficiency to heterologous glycoprotein extracts. The increased efficiency of hepatocytes to attach to kidney biomatrix-derived glycoproteins showed a linear correlation with the decreased glucagon binding capacity of their isolated plasma membranes. An epithelioid cell-line derived from kidney (MDCK) attached with higher efficiency to kidney than to liver glycoproteins. These results suggest that biomatrices may contain specific glycoproteins needed for attachment and survival of their epithelial cells. This specificity is lost during the proliferative state of regenerating and tumoral hepatocytes and could be important in the general mechanism of tumor dissemination and metastases.

Animals↗

PubMed2005

Analysis and elimination of artifacts in indirect covariance NMR spectra via unsymmetrical processing.

Indirect covariance NMR offers an alternative method of extracting spin-spin connectivity information via the conversion of an indirect-detection heteronuclear shift-correlation data matrix to a homonuclear data matrix. Using an IDR (inverted direct response)-HSQC-TOCSY spectrum as a starting point for the indirect covariance processing, a spectrum that can be described as a carbon-carbon COSY experiment is obtained. These data are analogous to the autocorrelated 13C-13C double quantum INADEQUATE experiment except that the indirect covariance NMR spectrum establishes carbon-carbon connectivities only between contiguous protonated carbons. Cyclopentafuranone and the complex polynuclear heteroaromatic naphtho[2',1':5,6]-naphtho[2',1':4,5]thieno[2,3-c]quinoline are used as model compounds. The former is a straightforward example because of its well-resolved proton spectrum, while the latter, which has considerable resonance overlap in its congested proton spectrum, gives rise to two types of artifact responses that must be considered when using the indirect covariance NMR method.

Journal Article↗

PubMed1992

Beyond Campbell and Fiske: assessment of convergent and discriminant validity.

While it is not an innovation in the more established social sciences, the multitrait multimethod (MTMM) technique (Campbell & Fiske, 1959) and additional, more powerful statistical methods of interpreting a MTMM matrix of correlations, have not been used extensively in nursing to assess construct validity of new instruments. This article reviews the Campbell and Fiske method for the assessment of convergent and discriminant validity, reviews the application of the method in the nursing literature, and describes the limitations of the original method. In addition, the procedures, strengths, and limitations of the analysis of variance and confirmatory factor analytic approaches to the quantification of Campbell and Fiske's criteria are described.

Data Interpretation, Statistical↗

PubMed2002

Mitogen-induced, FAK-dependent tyrosine phosphorylation of the SSeCKS scaffolding protein.

The ability of mitogens to rapidly induce tyrosine phosphorylation of cellular proteins has been taken as evidence of participation in subsequent signaling pathways. SSeCKS, a major protein kinase C (PKC) substrate with protein scaffolding and tumor suppressive properties, becomes tyrosine phosphorylated in NIH3T3 and rodent embryo fibroblasts after short-term treatment with epidermal growth factor (EGF), platelet-derived growth factor (PDGF), or fetal calf serum in the presence of pervanadate, but not by treatment with insulin or insulin-like growth factor-1. The relative phosphotyrosine level on SSeCKS was higher in actively dividing cells than in confluent cultures. Tyrosine phosphorylation of SSeCKS was apparent in cells deficient in Src, Fyn, Yes, or Abl tyrosine kinases or in NIH3T3 cells expressing a temperature-sensitive v-Src allele, but not in FAK-deficient embryo fibroblasts. Purified FAK or Src enzyme failed to directly phosphorylate SSeCKS in vitro. EGF failed to induce SSeCKS tyrosine phosphorylation in FAK-/- fibroblasts, indicating that the EGF receptor is probably not the direct kinase of SSeCKS. Phosphorylation under these conditions was rescued by the transient reexpression of wt-FAK but not FAK mutated at Y397, a major autophosphorylation and SH2-based docking site. Adhesion of FAK+/+ cells to fibronectin failed to significantly induce SSeCKS tyrosine phosphorylation although FAK was activated, suggesting that SSeCKS phosphorylation is mediated through a growth factor receptor-FAK rather than an integrin-FAK pathway. Moreover, PDGF could induce SSeCKS tyrosine phosphorylation in the absence of FAK activation, suggesting a role for FAK SH2-based docking rather than kinase activity. Immunofluorescence analysis showed that in FAK-/- cells, SSeCKS costains along F-actin stress fibers, in contrast to FAK+/+ cells, where most SSeCKS stains at the cell edge and along a cortical cytoskeletal matrix. This correlated with increased coprecipitation of SSeCKS with biotin-phalloidin-bound F-actin from FAK-/- compared to FAK+/+ cell lysates. Similarly, bacterially expressed, unphosphorylated SSeCKS cosedimented with F-actin in ultracentrifugation assays. These data suggest that mitogen-induced, FAK-dependent tyrosine phosphorylation of SSeCKS modulates its binding to the actin-based cytoskeleton, suggesting a role for SSeCKS in mitogen-induced cytoskeletal reorganization.

3T3 Cells↗

PubMed1997

XTT-colorimetric assay as a marker of viability in cryoprocessed cardiac valve.

This study sought to evaluate the use of tetrazolium salt XTT reduction as an indicator of valvular viability in a cryoprocessed porcine cardiac homograft model. The XTT tetrazolium assays was based on the metabolic reduction of Sodium 3'-[1-(phenylamino-carbonyl)-3,4-Tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate. The relationship between XTT reduction and: (1) leaflet tissue with various weight (n = 24); (2) morphometric evaluation (n = 30); (3) cadaveric ischemic intervals (n = 30); (4) freeze-thawing (n = 30) has been studied. The measurement of XTT reduction were significantly correlated with the weight of cardiac leaflets, in the range of 30 to 180mg (y=0.015x-0.063; r=0.99). Compared to morphometry of valvular damage, the reduction of mitochondrial enzymatic activity in cardiac leaflets was correlated with matrix cells without irreversible damage (r=0.89, P<0.005). The depletion of XTT reduction occurred dependent of ischemic time intervals. In general, freeze-thawing reduced more than 20% activity of mitochondrial dehydrogenase. We concluded that XTT tetrazolium assay is highly sensitive to determine valvular injury. The study demonstrated its potential for testing of cryopreserved cardiac valve.

Animals↗

PubMed1982

[Principle factors and symptom complexes in delirium tremens, factor and a group analytic study].

Before treatment 80 unselected patients suffering from delirium tremens were examined with regard to 13 psychopathological criteria. For the data a matrix of correlation was computed and it was factor analyzed according to the principal-component method. In consideration of the course of the value-curve two factors were interpreted. The result, however, is an undetailed classification. In addition to that, the data were cluster-analyzed according Ward. The results of the multivariate statistical analysis admit the assumption of two great, though heterogenous groups of symptoms (hallucination/vigilance). Factor I comprises the symptoms, disorder of orientation and consciousness, sweating, agitation and tremor on its positive pole, the duration of the delirant state on its negative pole. Factor II combines paranoid-hallucinatory symptoms, fearful affects and suggestibility on its positive pole, while on its negative, there are happy affect and grand-mal seizures. The bipolarity of this factor and additional diagnoses show that paranoid-hallucinatory symptoms without disorder of consciousness and grand-mal seizures mutually exclude each other. From this a differential therapy treating patients suffering from paranoid-hallucinatory symptoms with neuroleptics (e.g. Haloperidol) can be deduced, while the danger of grand-mal seizures has to be considered when disorders of consciousness appear.

Alcohol Withdrawal Delirium↗

PubMed1982

[Neurophysiologic aspects of psychoorganic deficiency problems of depressive disorders of the involutional age].

From a multidimensional viewpoint 40 depressive patients of involutional age (mean age 55 years) were evaluated in terms of an operationally defined deficiency syndrome, i.e. vital reduction per organic brain coloration to establish a neurobiologic matrix of correlation between the level of clinical psychopathology and neurophysiology. A subtle diagnosis by means of evoked potentials (SEP and VEP) measuring the neuronal infrastructure allows for a global evaluation of sensory-specific "cortical-subcortical functional integrity", otherwise missed in terms of the conventional EEG. In both vitally reduced patients and in probands who were diagnosed as having an organic brain syndrome because of clinical psychopathologic phenomenology, impaired bioelectric signal processing, increased neuropsychological deficits, risk factors and enlargement of the third ventricle were measured together with a chronic course of the nosologically classified disease. Compared with depressive patients who may have any deficiency factor, and healthy elderly probands (mean age 86 years), a deficiency syndrome is suggested as being defined as a polysystemic aging process which is dynamically induced by endogenous and exogenous factors, thus, being time dependent. Although there are correlative results between the disciplines, an abnormal (neuronal) functional diagram should only be used in a pathoplastic sense as an indicative and associative reaction of the CNS to premature aging processes at various levels.

Aged↗

PubMed1991

The effect of malate on propionate mitochondrial toxicity.

Propionic acidemia occasionally produces a toxic encephalopathy resembling Reye's syndrome, indicating disruption of mitochondrial metabolism. Liver mitochondria respiratory control ratios were reduced 46% by 5 mM propionate; inhibition correlated with matrix propionyl-CoA levels. L-Malate prevented the toxic effect of propionate and reduced the propionyl-CoA matrix concentration by 62%. The beneficial effect of L-malate is apparently due to stimulation of succinate efflux because the effect is blocked by benzylmalonate, an inhibitor of the dicarboxylate carrier. Matrix concentration of label from [1-14C]propionate was not affected by L-malate and/or benzylmalonate. L-Malate may be useful in the treatment of patients with propionic acidemia.

Acyl Coenzyme A↗

PubMed2006

The recognition and prediction of sigma70 promoters in Escherichia coli K-12.

Based on the conservation analysis of the 683 latest experimentally verified sigma(70)-promoter sequences of Escherichia coli K-12, it is found that the conservative hexamers segments in different sites play a key role of promoter regions, a novel position-correlation scoring matrix (PCSM) algorithm for predicting sigma(70) promoter is presented. The predictive capacity of the algorithm is tested by 10-cross validation test. The results show that the overall prediction accuracies (sensitivity) and specificity are 91% and 81%, respectively. By selecting the 683 experimentally verified sigma(70) promoters as training set and searching for the complete sequence in E. coli K-12 with 4639221bp. Results show that the 100% of the 683 experimentally verified sigma(70) promoters have been identified and some possible promoters are predicted.

Algorithms↗

PubMed2005

Repair after cholestatic liver injury correlates with neutrophil infiltration and matrix metalloproteinase 8 activity.

BACKGROUND: Although timely surgical treatment of liver disease can interrupt inflammation and reduce fibrosis, the mechanisms of repair are unknown. We questioned whether these mechanisms of repair include changes in the inflammatory infiltrate and associated biological activity of matrix metalloproteinases (MMPs) 8 and 2. METHODS: Rats (n >or= 3) underwent biliary ductal suspension for 7 days followed by decompression. Livers were collected after 7 days of obstruction (d0) and after 2, 5, and 7 days of repair (d2, d5, d7, respectively), and assessed morphometrically for collagen, polymorphonuclear cells (PMNs), Kupffer cells (KCs), and inflammatory mononuclear phagocytes (MNPs). In situ zymography was performed by using fluorogenic substrates for MMP-8 and MMP-2 to spatially localize enzymatic activity. RESULTS: Cholestatic injury resulted in significantly elevated (P <or= .001) collagen deposition (3-fold), and elevated numbers of MNPs (10-fold), KCs (5-fold), and PMNs (4-fold), compared with shams. PMNs remained elevated through d7, while collagen deposition, KCs, and MNPs returned to sham levels by d2. In situ zymography showed no significant changes in MMP-2 activity after cholestatic injury and repair. MMP-8 activity was significantly (P <or= .05) elevated only during repair. Activity was localized to fibrotic portal triads containing PMNs. CONCLUSIONS: Cholestatic injury results in increased fibrosis, MNPs, KCs, and PMNs but no MMP-2 or MMP-8 activity. Biliary decompression results in increased MMP-8 activity co-localized to areas of portal fibrosis and PMN accumulation. We conclude that secretion of MMP-8 by neutrophils may play a critical role in resolving the fibrotic scar generated during cholestasis.

Animals↗

PubMed1979

Conservation of chain reversal regions in proteins.

Using the bend frequencies based on 29 proteins in the previous paper (Chou and Fasman, 1979), beta-turn probability profiles were calculated for the C-peptides of 10 mammalian proinsulins, for 7 proteinase inhibitors, and for 12 species of pancreatic ribonucleases. Beta-turn correlation coefficient matrix tables were also computed to obtain the statistical mean between 45 pairs of proinsulin C-peptides, less than Ct greater than = 0.57 +/- 0.31; 21 pairs of proteinase inhibitors, less than Ct greater than = 0.73 +/- 0.13; and 66 pairs of ribonucleases, less than Ct greater than = 0.83 +/- 0.08. Despite relatively low sequence conservation in these three sets of proteins, beta-turns were predicted to be highly conserved: 33% sequence vs. 78% bend for the proinsulins, 20% sequence vs. 85% bend for the proteinase inhibitors, and 65% sequence vs. 92% bend for the ribonucleases. These results suggest that chain reversal regions play an essential role in keeping the active structural domains in hormones and enzymes intact for their specific biological function.

Amino Acid Sequence↗

PubMed2003

Altered morphology in cultured rat intestinal epithelial IEC-6 cells is associated with alkaline phosphatase expression.

Non-transformed, rat intestinal epithelial cells (IEC-6), and human intestinal colonic carcinoma cells (CACO-2) have both been used to study processes of epithelial cell differentiation. However, only CACO-2 cells have been described as spontaneously expressing phenotypic changes of differentiation in culture. We report here that when IEC-6 cells are grown in post-confluent culture, they develop structural changes similar to those seen in cells induced to differentiate by culture on Englebreth-Holm-Swarm (EHS) extracellular matrix proteins. Correlated with this morphological change is loss of nuclear localization of c-myc protein and development of cell surface alkaline phosphatase (ALP) enzymatic activity. Messenger RNAs for liver and intestinal isoforms of ALP were expressed in both pre- and post-confluent cells. Inhibition of ALP activity in post-confluent cells by levamisole indicated the expressed ALP activity to be of the liver isoform. We suggest the expression of ALP activity, which occurs concomitantly with morphological alterations in post-confluent IEC-6 cells, represents increased expression and localization to the cell surface of the liver isoform of ALP. Cultured IEC-6 cells may provide a non-transformed, in vitro alternative to CACO-2 cells for study of epithelial cell differentiation.

Alkaline Phosphatase↗

PubMed2003

Wear performance of ultrahigh molecular weight polyethylene/quartz composites.

Ultrahigh molecular weight polyethylene (UHMWPE)/quartz composites were compression molded in the presence of organosiloxane, and then hydrolyzed. The used organosiloxane is vinyl tri-ethyloxyl silane. The gelation, the melting behavior, the crystallinity, the mechanical properties and the wear resistance of UHMWPE/quartz composites were investigated. The results showed that organosiloxane can act as a cross-linking agent for UHMWPE matrix and serve as a coupling agent for improving the bonding between the quartz particles and the UHMWPE matrix. The correlation between the various properties and the morphology of the composites has been discussed. At about 0.5phr organsiloxane while the degree of crystallinity of the composite is at the peak value of 57%, the mechanical properties and the wear resistance of UHMWPE/quartz composites reaches their maximum.

Biocompatible Materials↗

PubMed2003

Electrochemiluminescent biosensors array for the concomitant detection of choline, glucose, glutamate, lactate, lysine and urate.

A multifunctional bio-sensing chip was designed based on the electrochemiluminescent (ECL) detection of enzymatically produced hydrogen peroxide. Six different oxidases specific for choline, glucose, glutamate, lactate, lysine and urate were non-covalently immobilised on imidodiacetic acid chelating beads (glucose oxidase only) or on diethylaminoethyl (DEAE) anion exchanger beads, and spotted on the surface of a glassy carbon foil (25 mm(2) square), entrapped in PVA-SbQ photopolymer. The chip measurement was achieved by applying during 3 min a +850 mV potential between the glassy carbon electrode and a platinum pseudo-reference, while capturing a numeric image of the multifunctional bio-sensing chip with a CCD camera. The use of luminol supporting beads (DEAE-Sepharose) included in the sensing layer was shown to enable the achievement of spatially well defined signals, and to solve the hydrogen peroxide parasite signal which appeared between contiguous spots using luminol free in solution. The detection limits of the different biosensor were found to be 1 microM for glutamate, lysine and uric acid, 20 microM for glucose and 2 microM for choline and lactate. The detection ranges were 1-25 microM (uric acid), 1 microM-0.5 mM (glutamate and lysine), 20 microM-2 mM (glucose) and 2 microM-0.2 mM (choline and lactate). The ECL chip was used for the detection of glucose, lactate and uric acid in human serum matrix. Good correlations between measured and expected values were found without the need of internal calibration of the sample, demonstrating the potentiality of the ECL multifunctional bio-sensing chip.

Biosensing Techniques↗

PubMed1996

The "equal environments assumption" in MZ-DZ twin comparisons: an untenable premise of psychiatric genetics?

The comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA--the "equal environments assumption"--as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called "path analysis". It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the "heritability" estimate--often taken to mean the influence of trait-specific genes--is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that "heritability" does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called "heritability".

Humans↗

PubMed2004

Cartesian-structure analysis in cast films by advanced infrared multiple-angle incidence resolution spectroscopy.

Multiple-angle incidence resolution spectroscopy (MAIRS) has been improved to be an advanced algorithm so that the Cartesian structure in organic thin films can be analyzed. The infrared MAIRS technique was originally proposed as a totally new spectroscopic technique to reveal structural anisotropy in thin films on an infrared-transparent substrate, which yields both in-plane- (IP; X and Y) and out-of-plane (OP; Z)-mode spectra from an identical sample. Since this technique employs an analytical concept based on a signal decomposition of light intensity (not absorbance spectra), the algorithm intrinsically has high potential for further development. In the present study, the theoretically deduced matrix that correlates the light intensity to the angle of incidence has been modified to further decompose the IP-mode spectrum into X and Y components. As a result, anisotropic measurements of infrared spectra of thin film have become possible for the X, Y, and Z directions (Cartesian coordinate) simultaneously. With this advanced algorithm, the Cartesian structural changes in a cast film prepared on a germanium substrate have readily been analyzed, and a change from the biaxial to the uniaxial film structure with aging has spectroscopically been revealed.

Journal Article↗

PubMed2002

Poly(vinyl alcohol) hydrogels as hydrophilic matrices for the release of lipophilic drugs loaded in PLGA nanoparticles.

Poly(vinyl alcohol) (PVA) hydrogels prepared by a freeze-thawing procedure were evaluated as matrices for the release of water-insoluble drugs such as dexamethasone. As it is impossible to directly entrap a lipophilic drug into a hydrophilic matrix, a novel mechanism has been designed based on producing biodegradable nanoparticles loaded with the drug, that could then be entrapped into the hydrogels. Nanoparticles were prepared by a solvent evaporation technique using a biodegradable copolymer of poly(lactic acid)-poly(glycolic acid) (PLGA). The effects of several processing parameters on particle properties were investigated. The drug release from free nanoparticles was compared to that from the nanoparticles entrapped into the PVA matrices. It was observed that the release profile of the drug is not significantly affected by the PVA matrix. A correlation was found between the amount of drug released and the PVA concentration in the hydrogels: the percentage of drug released, as a function of time, decreased by increasing PVA concentration, indicating that PVA concentration can be used as a tool in modulating the release of the drug.

Journal Article↗