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At least 919 records · Page 51Linked to original sources
PubMed1997

Contrast-enhanced magnetic resonance imaging in a spinal epidural tumor model.

RATIONALE AND OBJECTIVES: A spinal epidural tumor model was developed, using the VX-2 adenocarcinoma in rabbits, to assess the strengths and weaknesses of magnetic resonance (MR) as a cross-sectional imaging modality for the evaluation of epidural neoplastic disease. High-resolution MR images were acquired both before and after intravenous gadolinium chelate injection, assessing lesion detectability and efficacy of imaging technique. METHODS: An adenocarcinoma tumor (VX-2) was produced in the epidural space of six New Zealand White rabbits and subsequently studied on a 1.5 tesla whole body MR scanner. VX-2 tumor tissue was removed from the thigh of a carrier rabbit, minced, and screened. Under fluoroscopic guidance, 0.2 mL of the tumor preparation was then injected into the epidural space of the experimental rabbits. The injection was performed at the L5-6 level using an epidural needle and polyethylene tubing sleeved within the needle. The rabbits were imaged using a circular small parts surface coil 5 to 15 days after the epidural injection. In all six animals, one complete MR exam was obtained within the time frame of days 9 to 11. T1- and T2-weighted axial scans were obtained before contrast injection, with the T1 scans acquired both with and without fat saturation. Postcontrast T1 scans also were obtained, using fat saturation, after the injection of 0.1 and 0.3 (cumulative dose) mmol/kg gadoteridol (Gd HP-DO3A; ProHance) in all animals. The film images were interpreted in a prospective fashion by a single neuroradiologist who was masked to imaging technique and contrast dosing. The digital data was analyzed by region of interest measurement. At the end of the imaging studies, the animals were sacrificed and the epidural lesion confirmed by gross and microscopic exam. RESULTS: On a prospective masked read of the MR films, epidural tumor was depicted best on postcontrast fat saturation T1-weighted scans using a cumulative contrast dose of 0.3 mmol/kg. Substantial contrast enhancement of the tumor was observed in all instances on postcontrast scans. The precontrast T1-weighted scan was least efficacious for lesion identification and differentiation from the compressed spinal cord. Depending on the pulse sequence used, one (T2-weighted) to three (T1-weighted without fat saturation) of the lesions could not be identified prospectively on precontrast scans. Lesion growth with time after implantation was chronicled by MR imaging, accompanied by progression of symptoms. On region of interest analysis, differentiation of epidural tumor from normal cord was greatest (11.6 +/- 6.1) on postcontrast scans using a cumulative contrast dose of 0.3 mmol/kg. The level of differentiation achieved was twice that of postcontrast scans using a contrast dose of 0.1 mmol/kg (5.9 +/- 3.6). These results were superior on statistical analysis to that with all other scan techniques (P = 0.002-0.0005). Cord and tumor could not be differentiated on the basis of signal intensity, with any statistical significance, using precontrast T1 and T2 scans. The lesions were confirmed in each animal by gross and microscopic exam. On inspection of the gross specimen, the tumors were noted to be located in the epidural space and to cause cord compression. On microscopic exam, the tumor was composed of epithelial cells that were moderately pleomorphic. CONCLUSIONS: In the New Zealand White rabbit, an epidural tumor could be created consistently using the described percutaneous approach. These lesions are suitable for MR imaging studies, examining lesion detectability and efficacy of imaging technique. The lesions created in the current study could not be diagnosed prospectively in all cases on precontrast T1 and T2 scans images. Postcontrast scans were most efficacious for diagnosis and lesion delineation, with high-dose (0.3 mmol/kg) scans superior to standard dose (0.1 mmol/kg).

Adenocarcinoma↗
PubMed2002

Cloning and characterization of Ehox, a novel homeobox gene essential for embryonic stem cell differentiation.

We report here the identification and characterization of a novel paired-like homeobox-containing gene (Ehox). This gene, identified in embryonic stem (ES) cells, is differentially expressed during in vitro ES cell differentiation. We have assessed Ehox function using the ES cell in vitro differentiation system. This has involved molecular and biological analyses of the effects of sense or antisense Ehox expression (using episomal vectors) on ES cell differentiation. Analysis of antisense Ehox-expressing ES cells indicates that they are unable to express marker genes associated with hematopoietic, endothelial, or cardiac differentiation following removal of leukemia inhibitory factor. In contrast, overexpression of Ehox using the sense construct accelerated the appearance of these differentiation markers. ES cell self-renewal and differentiation assays reveal that inhibition of Ehox activity results in the maintenance of a stem cell phenotype in limiting concentrations of leukemia inhibitory factor and the almost complete impairment of the cardiomyocyte differentiation capacity of these cells. We therefore conclude that Ehox is a novel homeobox-containing gene that is essential for the earliest stages of murine ES cell differentiation.

Amino Acid Sequence↗
PubMed2004

Comparative study of proteome between primary cancer and hepatic metastatic tumor in colorectal cancer.

AIM: To identify the differential proteins associated with colorectal cancer genesis and hepatic metastasis. METHODS: Hydrophobic protein samples were extracted from normal colorectal mucosa, primary cancer lesion and hepatic metastatic foci of colorectal cancer. With two-dimensional electrophoresis and image analysis, differentially expressed protein spots were detected, and the proteins were identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry and peptide mass fingerprint analysis. RESULTS: Significant alterations of the proteins in number and expression levels were discovered in primary cancer and hepatic metastatic foci, the expression of a number of proteins was lost in 25-40 ku, but protein spots was increased in 14-21 ku, compared with normal mucosa. Nine differentially expressed protein spots were identified. Three proteins expressed in normal mucosa, but lost in primary cancer and hepatic metastasis, were recognized as calmodulin, ribonuclease 6 precursor and mannosidase-alpha. Proapolipoprotein was expressed progressively from normal mucosa to primary cancer and hepatic metastasis. The differentially expressed protein of beta-globin was found in normal mucosa and hepatic metastatic tumor, but lost in primary cancer lesion. Cdc 42, a GTP-binding protein, was identified in hepatic metastasis. The protein spots of C4 from primary cancer, M7 and M9 from hepatic metastasis had less homology with the proteins in database. CONCLUSION: Variations of hydrophobic protein expression in colorectal cancer initiation and hepatic metastasis are significant and can be observed with two-dimensional electrophoresis. The expression of calmodulin, ribonuclease 6 precursor and mannosidase-alpha is lost but the expression of proapolipoprotein is enhanced which is associated with colorectal cancer genesis and hepatic metastasis. Cdc 42 and beta-globin are expressed abnormally in hepatic metastasis. Protein C4, M7 and M9 may be associated with colorectal cancer genesis and hepatic metastasis.

Adult↗
PubMed2001

Analysis of single-cell differences by use of an on-chip microculture system and optical trapping.

A method is described for continuous observation of isolated single cells that enables genetically identical cells to be compared; it uses an on-chip microculture system and optical tweezers. Photolithography is used to construct microchambers with 5-microm-high walls made of thick photoresist (SU-8) on the surface of a glass slide. These microchambers are connected by a channel through which cells are transported, by means of optical tweezers, from a cultivation microchamber to an analysis microchamber, or from the analysis microchamber to a waste microchamber. The microchambers are covered with a semi-permeable membrane to separate them from nutrient medium circulating through a "cover chamber" above. Differential analysis of isolated direct descendants of single cells showed that this system could be used to compare genetically identical cells under contamination-free conditions. It should thus help in the clarification of heterogeneous phenomena, for example unequal cell division and cell differentiation.

Bacteria↗
PubMed1988

Identification of ventricular tachycardia using intracavitary ventricular electrograms: analysis of time and frequency domain patterns.

Tachycardia detection by implantable antitachycardia devices using rate alone has major limitations. Several alternative methods have been proposed to distinguish ventricular tachycardia or ventricular fibrillation from normal sinus rhythm using intracardiac electrograms. These methods have not been tested, however, for recognition of ventricular tachycardia in patients with abnormal surface QRS conduction during sinus rhythm or with antiarrhythmic drug therapy. In this study, three techniques for the identification of ventricular tachycardia from intracavitary bipolar ventricular electrograms were examined and compared: correlation waveform analysis, amplitude distribution analysis, and spectral analysis using Fast Fourier transformation. Thirty episodes of induced monomorphic ventricular tachycardia were analyzed and compared sinus rhythm in four groups of patients with: I. Normal surface QRS conduction during sinus rhythm without antiarrhythmic drug therapy (five episodes); II. Intraventricular conduction delay or bundle branch block during sinus rhythm without antiarrhythmic drug therapy (nine episodes); III. Normal surface QRS conduction during sinus rhythm with antiarrhythmic therapy (six episodes); and IV. Intraventricular conduction delay or bundle branch block during sinus rhythm with antiarrhythmic drug therapy (ten episodes). Correlation waveform analysis had 100% sensitivity and specificity in distinguishing ventricular tachycardia from sinus rhythm, even in the presence of an intraventricular conduction delay, bundle branch block, and antiarrhythmic drug therapy. In contrast, amplitude distribution analysis differentiated 15/30 episodes (50.0%) of ventricular tachycardia from sinus rhythm, and a maximum of 18/30 episodes (60.0%) of ventricular tachycardia were identified by special analysis using Fast Fourier transformation. Correlation waveform analysis appears to be a reliable technique to discriminate ventricular tachycardia from sinus rhythm using intracavitary ventricular electrograms. Its computational demands are modest, making it suitable for consideration in an implantable antitachycardia device.

Adolescent↗
PubMed1995

The C-terminal zinc finger of GATA-1 or GATA-2 is sufficient to induce megakaryocytic differentiation of an early myeloid cell line.

The GATA-1 and GATA-2 transcription factors, which each contain two homologous zinc fingers, are important hematopoietic regulators expressed within the erythroid, mast cell, and megakaryocytic lineages. Enforced expression of either factor in the primitive myeloid line 416B induces megakaryocytic differentiation. The features of their structure required for this activity have been explored. The ability of 12 GATA-1 mutants to promote 416B maturation was compared with their DNA-binding activity and transactivation potential. Differentiation did not require any of the seven serine residues that are phosphorylated in vivo, an N-terminal region bearing the major transactivation domain, or a C-terminal segment beyond the fingers. Removal of a consensus nuclear localization signal following the second finger did not block differentiation or nuclear translocation. The N-terminal finger was also dispensable, although its removal attenuated differentiation. In contrast, the C-terminal finger was essential, underscoring its distinct function. Remarkably, only 69 residues spanning the C-terminal finger were required to induce limited megakaryocytic differentiation. Analysis of three GATA-2 mutants led to the same conclusion. Endogenous GATA-1 mRNA was induced by most mutants and may contribute to differentiation. Because the GATA-1 C-terminal finger could bind its target site but not transactivate a minimal reporter, it may direct megakaryocytic maturation by derepressing specific genes and/or by interacting with another protein which provides the transactivation function.

3T3 Cells↗
PubMed1988

Quantification of cells recovered by bronchoalveolar lavage. Comparison of cytocentrifuge preparations with the filter method.

Controversy exists as to the appropriate methods to use in the processing of bronchoalveolar lavage (BAL) fluid for total cell numbers and cellular differential analysis. It has been shown that cell losses (primarily lymphocytes) occur by the most commonly employed methods. Therefore, we examined the total cell and differential counts obtained by several methods of cytocentrifuge preparation and by the filter preparation in 46 consecutive patients with interstitial lung disease and 29 healthy volunteers undergoing bronchoalveolar lavage. The retrieved lavage fluid was pooled, and an aliquot was used to determine the total cell count, cell viability, and the differential cell count by the filter and cytocentrifuge techniques. The remaining fluid was centrifuged (800 g for 10 min), and the cell pellet was resuspended in Hank's balanced salt solution without Ca2+ and Mg2+. An aliquot of these centrifuged and resuspended cells was used for repeat determination of the cell viability, total cell count, and cellular differential by cytocentrifuge technique. Autologous serum was added to another aliquot of these centrifuged and resuspended cells to arrive at a 10% protein solution, and the cellular differential obtained by cytocentrifuged preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

[Memory strategies in the elderly].

The frequency and preference of memory strategies were investigated in a group of independently living older adults (N = 111, 45-85 year) who were interested in memory training because of subjective and objective memory problems. Mokken scale analysis identified, besides the use of 'no strategy', four strategy scales, viz. encoding, retrieval, general, and external strategies. These five scales allowed for a differentiated analysis of strategy use. Frequency judgments showed that external strategies were used most frequently, followed by retrieval strategies. Encoding strategies were used least often. Reports on the preference of strategies in specific situations showed that subjects reported to use specific strategies in the majority of situations, although here too external strategies were used most generally. Strategy reports were more related to psychological variables (mental speed, primary memory ability, need for cognition and memory complaints) than to demographic characteristics (age, educational level and sex). The explained variances, however, were low which suggests substantial individual differences in use and preference of memory strategies.

Adaptation, Psychological↗
PubMed2005

Clonal multilineage differentiation of murine common pluripotent stem cells isolated from skeletal muscle and adipose stromal cells.

Pluripotent stem cells (PSCs) with transdifferentiation capacity may provide useful therapeutic modalities in the areas of cellular restoration and regenerative medicine. The utility of PSCs depends on their ability to respond to different stimuli and to adapt to tissue-specific differentiation conditions. Given that a number of cells possessing characteristics of PSCs have been identified and isolated from several adult murine tissues, we hypothesized that a common PSC may exist in multiple murine tissues and that these cells may either reside permanently in specific sites or continue to circulate and colonize tissues as needed. Previous data from our laboratory suggest that PSCs exhibiting an immunophenotype of CD45(-)Sca-1(+)c-kit(-)Thy-1(+) can be isolated from multiple murine tissues and may represent putative common PSCs (CoPSCs). To investigate whether the multiple tissue differentiation potential observed with these cells resulted from the presence of different tissue-restricted progenitors within CD45(-)Sca-1(+)c-kit(-)Thy-1(+) cells or was the product of clonal differentiation of CoPSCs, clonality studies were performed. Single skeletal muscle (SM)-derived CoPSCs were expanded for 10 days, and progeny cells were split into three culture conditions designed to stimulate myogenic, adipogenic, and neurogenic differentiation. Analysis of 600 clones indicated that 2.16%, 0.83%, and 0.33% of the total number of plated single cells were capable of unipotent, bipotent, and tripotent differentiation, respectively, into combinations of myocytes, adipocytes, and neuronal cells. Given that SM-derived CoPSCs represent 4.78% of the total cells analyzed, tripotent CoPSCs made up 0.016% of the total muscle cells. Similar results were obtained in clonal analyses using adipose stromal cell (ASC)-derived CoPSCs, suggesting that both SM- and ASC-derived CoPSCs may be phenotypically and functionally identical. Taken together, these data demonstrate that a common PSC can be identified in different murine tissues and suggest that a small fraction of these cells are capable of clonal differentiation into multiple cell types.

Adipocytes↗
PubMedDate not supplied

Identification of differentially expressed genes associated with colorectal cancer liver metastasis.

The molecular mechanisms underlying successful metastasis of primary colorectal tumour to the liver remain unknown. We have used suppression subtractive hybridisation (SSH) and reverse Northern dot blot analysis to profile the mRNA expression patterns of a primary colorectal cancer and its liver metastasis. After SSH and reverse Northern dot blot analysis, differential expression was confirmed in 17 clones from the forward, and 13 clones from the reverse subtracted cDNA library. Four clones showed no significant sequence identities with any known sequences in the GenBank data base and likely to represent novel genes whose up- or down-regulation is associated with colorectal liver metastasis. Interestingly, one of the 13 down-regulated clones displayed 99% sequence identity with the BRCA1 tumour suppressor gene. Since promoter methylation is a direct cause of transcription silencing of the BRCA1 gene in approximately 10-20% of human breast cancer we further investigated its promoter methylation status in ten primary colorectal tumour samples, but revealed no evidence of promoter methylation.

Adult↗
PubMed1993

[Presbycusis].

Hearing loss in the elderly is the most common type of hearing impairment. The term presbyacusis has been used to describe this category of hearing loss when there are no other etiological factors. However, the term is not precise, because any of several locations along the auditory pathway may be involved to produce the symptoms. The diagnosis is based more on the course of the hearing loss and the associated biological signs of aging than on specific criteria. The loss of speech-understanding ability is one of the most important indicators for a therapeutic intervention, which generally aims at amplification using a personal hearing aid. An improvement in speech-understanding ability with a hearing aid depends on several complex factors, and there is a large amount of intersubject variability in the benefit derived from amplification, even when the magnitude of the hearing loss is comparable. The aim of research on presbyacusis over the next several years--keeping in mind the demographic development in the industrialized countries--will be to further the differential analysis of the factors contributing to auditory communication disorders in the aging population.

Aged↗
PubMedDate not supplied

Statistical analysis in the differentiation between cases of serious acute pancreatitis and generalized peritonitis due to a perforated peptic ulcer.

Serious acute pancreatitis was considered by the authors as one of the diseases which must be distinguished from generalized peritonitis due to perforated peptic ulcer. An attempt was made to differentiate between these two conditions without reference to two factors, namely amylase value and intraperitoneal free air. Differential diagnosis by linear discriminant analysis, making full use of information such as the history of the present illness, general and abdominal findings and laboratory data, was undertaken. This resulted in a satisfactory predictive value, at least for sample cases. Lastly, items which seem to be important for differentiation between the diseases are discussed.

Acute Disease↗
PubMedDate not supplied

[Contribution of proteomic analysis to study cardiovascular physiopathology].

Proteomic is an innovative approach for determining without any priori the coordinated changes in protein levels contained in a biological sample. This technique now constitutes a powerful tool for revealing, in particular by differential analysis, biological responses and regulation of proteins. This field is becoming essential in each domain for fundamental and clinical biology, mainly in human medicine. It leads to improve the understanding of complex physiopathological processes like those involved in human pathologies, but also for identifying new biomarkers in order to consider new diagnostic and prognostic approaches and original therapeutic targets. The different proteomic techniques, essentially bi-dimensional electrophoresis and mass spectrometry, which benefit from recent technological developments, are presented in this article. A literature review summarize data obtained from proteomic works performed to have better understanding of mechanisms involved in cardiovascular diseases, first cause of morbidity and mortality in the world. Proteomic analysis performed in this area of research are promising, because of the lack of knowledge in the molecular interactions and the complexity of mechanisms involved, and of the impact of environmental risk factors. This impact is being generally only detectable at protein level. These works are only at the beginning and these approaches applied in cardiovascular field will meet a large success in the immediate future and should be promising.

Cardiovascular Diseases↗
PubMed1987

Evaluation of BCDE, a microcomputer program to analyze automated blood counts and differentials.

A microcomputer program (BCDE) has been developed to analyze automated blood cell counts and differentials' similarity to normal values or to 36 disease categories. In 50 normal subjects, the analytic program listed the correct diagnosis as the first diagnosis in 49 cases (the only diagnosis in 44) and second of two diagnoses in one case. In 182 subjects with known hematologic disorders, the correct diagnosis was listed first in 134 and second or third in an additional 40. Subjects with iron deficiency, heterozygous thalassemia, immune thrombocytopenia, anemia of chronic disease, reactive thrombocytosis, acute infection, and chronic leukemia had the disorder identified as the most likely one by the analytic program with both sensitivity greater than 80% and specificity greater than 98%. Subjects with acute leukemia, folate deficiency, sickle cell anemia, cytotoxic chemotherapy, and chronic liver disease had the disorder identified as most likely by the program with a sensitivity less than 80%. In a different 11 cases with known hematologic status, a panel of 37 physicians identified the disorder(s) or normality only 72% of the time, whereas the analytic program listed the correct diagnosis first in 10 of 11 (91%). The analytic program appears useful for both triage of normal from abnormal data and for the initial differential analysis of abnormal data.

Blood Cell Count↗
PubMed2026

Genomic hallmarks of depot medroxyprogesterone acetate-associated meningiomas.

BACKGROUND: Population-based studies have linked progestin exposure to increased meningioma risk. However, the molecular basis of meningiomas associated with depot medroxyprogesterone acetate (DMPA)-a common injectable contraceptive-remains undefined. METHODS: We performed an integrated clinicopathologic and genomic analysis of meningiomas from 10 women with long-term DMPA exposure. Tumors underwent histopathological analysis, targeted sequencing, and DNA methylation profiling. Data were integrated with reference cohorts (Baylor and Heidelberg) and analyzed through classifier assignment, consensus clustering, copy number analysis, differential methylation testing, and dimensionality reduction. RESULTS: Depot medroxyprogesterone acetate-associated meningiomas were all newly diagnosed, World Health Organization grade 1 tumors with a predilection for the anterior and central skull base (n = 6). Nine patients harbored multiple meningiomas. Four experienced regression of untreated meningiomas following DMPA cessation, while 5 demonstrated stabilization. Histopathology demonstrated relative overrepresentation of metaplastic morphology, an uncommon meningioma subtype. All DMPA-associated meningiomas mapped to benign molecular groups, and most exhibited low copy number alteration burden. Targeted sequencing revealed enrichment for TRAF7 mutations (n = 5), with no NF2 mutations detected. Eight tumors shared consensus cluster identity, with cohesive grouping on principal component analysis and t-distributed stochastic neighbor embedding. No differential methylation was identified at the progesterone receptor locus. CONCLUSIONS: Depot medroxyprogesterone acetate-associated meningiomas represent a recognizable phenotype within the broader NF2-wildtype/TRAF7-enriched spectrum of benign meningiomas, characterized by chromosomal stability, a shared methylation profile, tumor multiplicity, and regression or stabilization following DMPA cessation. While derived from a small single-institution cohort, these findings provide a molecular framework for understanding progestin-associated meningioma biology, reinterpreting epidemiologic literature, and informing population-level risk stratification.

Humans↗
PubMed1996

The noninvasive measurement of absolute cerebral deoxyhemoglobin concentration and mean optical path length in the neonatal brain by second derivative near infrared spectroscopy.

We have used second differential near infrared spectroscopy of water to determine the mean optical path length of the neonatal brain. By obtaining the ratio of the second differential features of deoxyhemoglobin to those of water, the absolute cerebral concentration of deoxyhemoglobin can be monitored continuously and noninvasively. Nineteen neonates were studied; the gestational age at birth varied from 23 to 38 wk, and the postconceptual age, when the spectra were recorded, ranged from 35 to 48 wk. The calculated mean deoxyhemoglobin concentration was 14.6 +/- 4.0 microM; the differential path length factor (mean optical path length/optode separation) calculated from the water peak at 730 nm was 4.66 +/- 1.01, and that calculated at the 830-nm peak was 3.91 +/- 0.75. These values are consistent with path length measurements using laser time-of-flight spectroscopy on postmortem neonates and phase-resolved spectroscopy on live neonates. Induced arterial oxygen saturation decreases from 98 to 93% showed no significant change in the mean optical path length, despite significant cerebral desaturation. Changes in the deoxyhemoglobin concentration after this procedure were identical, whether measured by second differential analysis at 760 nm or by multilinear regression over the wavelength range 740-900 nm. When combined with existing methods of measuring total cerebral hemoglobin concentration, second differential near infrared spectroscopy can be used to derive the mean cerebral oxygen saturation. A preliminary experiment outlined the feasibility of this approach and yielded a saturation value of 63%, consistent with near infrared sampling of a predominantly venous pool in the brain.

Brain↗
PubMed1978

[Analysis of gallstones by infrared spectrophotometry. Advantages and limits of the method (author's transl)].

Numerous clinicians criticise the insufficiency and imprecision, and the incoherency of the analyses of biological calculations by the usual clinical methods and thus frequently avoid prescribing such an examination. The authors propose the application of a physical method, infrared spectrophotometry for the qualitative and semi-quantitative determination of the composition of stones of all origins. They recall the often heterogeneous structure of the stones and emphasise the importance which they attribute of differential analysis by separate zones during careful dissection, the results of which may orient the therapeutic attitude of the clinician. The differentiation of a few crystalline structures and the study of complex mixtures are dealt with in the form of characteristic infrared spectra. The advantages and limits of the method compared with other technics of analysis are discussed.

Bilirubin↗