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At least 1,567 records · Page 87Linked to original sources
PubMed1989

Evaluation of cerebral blood flow data in stroke patients using a mapping system.

We retrospectively examined regional cerebral blood flow values in 78 patients in the stabilized phase of stroke to evaluate the consistency of lateralization compared with computed tomographic imaging. Examinations were performed using the xenon-133 inhalation technique, and the data were processed and displayed by a computer-assisted system of our own design that allows statistical analysis in real time and is suitable for clinical use. The consistency of lateralization correlated with computed tomographic findings was tested for absolute values, percent distribution, and asymmetries. The latter yielded the highest degree of sensitivity (in 83.3% of the patients the affected hemisphere was correctly identified). Absolute values showed at least one hypoperfused area in the affected hemisphere in 48.7% of the patients, and percent distribution did so in 57.7%. Furthermore, the combination of the three methods of data analysis yielded a sensitivity of 91%; the remaining 9% of the patients, however, exhibited some abnormalities of regional cerebral blood flow (bilateral or contralateral hypoperfusion). Although good agreement was found for lateralization by computed tomography and by the combined use of the three methods of analysis, a complete overlap between functional and structural examinations should not be expected. Problems concerning the sensitivity of the xenon-133 inhalation technique under conditions of low blood flow and the statistical analysis of regional cerebral blood flow data are discussed.

Administration, Inhalation↗
PubMed1997

A direct comparison of PET activation and electrocortical stimulation mapping for language localization.

Mapping eloquent language cortex in presurgical patients typically is accomplished using highly invasive direct cortical stimulation techniques. Functional imaging during language activation using positron emission tomography (PET) is a promising, noninvasive alternative that requires validation. In seven patients undergoing surgical evaluation for intractable epilepsy, we performed both direct cortical stimulation and PET activation mapping of language cortex using identical tasks. MRI, PET, and CT scans were coregistered to directly compare the location of language centers determined by cortical stimulation versus activation PET. We found that cortical regions that showed increased cerebral blood flow during both visual and auditory naming tasks were located in the same regions as subdural electrodes which disrupted language during electrical stimulation. Cortical regions underlying electrodes that did not disrupt language also showed no consistent changes in regional cerebral blood flow during PET activation. Used cautiously, PET activation produces language maps similar to those obtained with direct cortical stimulation, with more complete brain coverage and considerably less invasion.

Adolescent↗
PubMedDate not supplied

Ras family signaling: therapeutic targeting.

Mutationally activated and oncogenic versions of the ras genes were first identified in human tumors in 1982. This discovery prompted great interest in the development of anti-Ras strategies as novel, target-based approaches for cancer treatment. The three human ras genes represent the most frequently mutated oncogenes in human cancers. Consequently, a considerable research effort has been made to define the function of Ras in normal and neoplastic cells and to target Ras for cancer treatment. Among the anti-Ras strategies that are under evaluation in the clinic are pharmacologic inhibitors designed to prevent: (1) association with the plasma membrane (farnesyltransferase inhibitors), (2) downstream signaling (Raf and MEK protein kinase inhibitors), (3) autocrine growth factor signaling (EGF receptor inhibitors), or (4) gene expression (H-ras and c-raf-1). Although a number of these inhibitors have demonstrated potent anti-tumor activities in preclinical models, phase l-lll clinical trials have revealed unexpected complexities in Ras function and in the clinical development of target-based therapies. We review the current status of anti-Ras drug development, issues that have complicated their progression to the clinic, and possible future strategies for targeting Ras.

Alkyl and Aryl Transferases↗
PubMedDate not supplied

The evidence base for complementary and alternative medicine: methods of Evidence Mapping with application to CAM.

BACKGROUND: There is widespread concern regarding the adequacy of evidence for specific practices under the rubric of "complementary and alternative medicine" (CAM). OBJECTIVE: To map the evidence pertaining to many commonly used CAM practices. DESIGN: In 2000, the Yale Prevention Research Center was funded by the Centers for Disease Control and Prevention to conduct a "systematic review" of the evidence underlying CAM. The investigative team, working in collaboration with CAM practitioners, developed a systematic and replicable 9-step process termed evidence mapping. The process stipulates means for specifying the boundaries of the subject to be mapped in MeSH terms, and the characteristics used to situate retrieved articles in the overall map of evidence. SETTING: Yale Prevention Research Center, Derby, CT. RESULTS: Steps completed thus far have led to the identification of over 4,000 papers distributed across 207 condition-treatment pairs. Of these pairs, 58% (n = 121) have been studied with one or more RCTs (1,070 total RCTs), and 23% (n = 47) have been the subject of one or more meta-analyses (86 total meta-analyses). Thirty-seven condition/treatment pairs (18%) had no identifiable supporting studies. CONCLUSIONS: The novel methods of evidence mapping reported are useful and practical in characterizing the extent, distribution, and methodologic quality of research pertaining to a broad topic in medicine. Applied to CAM, they suggest that summary judgments about the quantity or quality of underlying evidence are overly simplistic.

Complementary Therapies↗
PubMed1992

Magnetic resonance imaging of the heart and the great vessels: morphology, function, and perfusion.

The capability of MR imaging to evaluate cardiovascular disease is developing faster than ever, as is well documented by the numerous contributions that have been made to the literature during the past year. As the field progresses, MR imaging will probably become one of the preferred investigational methods for the evaluation of cardiac function. The first stage of MR imaging development emphasized replication of commonly used methods for studying morphology and analyzing global ventricular performance. Thus, validated MR imaging methods exist for the assessment of ventricular' volume, ejection fraction, and mean wall stress. More recently, emphasis has been directed toward the evaluation of regional function and perfusion, using novel methods and attracting increasing interest from the cardiovascular research community. Studies reviewed here focus on both clinical results obtained using well-established MR imaging techniques and new results using innovative methods, further extending the usefulness of MR imaging. Topics discussed include congenital and ischemic heart disease and disease of the great vessels. Technical advances in flow and velocity mapping and in the evaluation of ventricular performance are also discussed.

Aortic Diseases↗
PubMedDate not supplied

Identifying genetic risk factors for osteoporosis.

Over the past decades epidemiological research of so-called "complex" diseases, i.e., common age-related disorders such as cancer, cardiovascular disease, diabetes, and osteoporosis, has identified anthropometric, behavioural, and serum parameters as risk factors. Recently, genetic polymorphisms have gained considerable interest, propelled by the Human Genome Project and its sequela that have identified most genes and uncovered a plethora of polymorphic variants, some of which embody the genetic risk factors. In all fields of complex disease genetics (including osteoporosis) progress in identifying these genetic factors has been hampered by often controversial results. Because of the small effect size for each individual risk polymorphism, this is mostly due to low statistical power and limitations of analytical methods. Genome-wide scanning approaches can be used to find the responsible genes. It is by now clear that linkage analysis is not suitable for this, but genome-wide association analysis has much better possibilities, as is illustrated by successful identification of risk alleles for several complex diseases. Candidate gene association analysis followed by replication and prospective multi-centred meta-analysis, is currently the best way forward to identify genetic markers for complex traits, such as osteoporosis. To accomplish this, we need large (global) collaborative studies using standardized methodology and definitions, to quantify by meta-analysis the subtle effects of the responsible gene variants.

Animals↗
PubMed1990

Synthesis of a recombinant DNA-derived HBV e antigen and its application in diagnosis.

The gene coding for HBV e antigen (HBeAg) and core antigen (HBeAg) are located in the C region of the HBV genome. In this paper 1.8 kb BamHI-EcoRI DNA fragment carrying HBc gene from adw2 HBV DNA was digested with Bal31 and HapII, a series of fragment with different length were produced and inserted into pUR222 and pUC18 vectors to construct various recombinant plasmids. Two new recombinants able to direct high level synthesis of HBeAg in E. coli were obtained. Recombinant HBeAg was then purified by DEAE chromatography and affinity chromatography. The preparation obtained were identified by electrophoresis and immunochemical analysis. Molecular weight of the recombinant HBeAg determined by SDS-PAGE was about 38 kd. It is considered to be a dimer of two fused antigen molecules in size of 19 kd. Bacterial extracts prepared from cells harboring one of the constructed plasmids have been used successfully as a diagnostic reagent for the detection of HBeAg and anti-HBe in human sera by ELISA.

Cloning, Molecular↗
PubMed1991

[Neurogenetics--the challenge for neurology. Part 1. Gene mapping and gene diagnostics].

Recent advances in gene mapping have provided distinct chromosomal locations for a number of neurological disease genes. Mapping strategies include the identification of chromosomal aberrations associated with disorders and the candidate gene approach which requires correct assumptions about the primary biochemical defect. The most successful strategy, linkage analysis, relies on family studies and allows the mapping of genes without knowledge of the molecular cause of a disorder. Once the chromosomal position for a disease gene is known, indirect DNA diagnosis becomes available, providing risk estimates for individuals in affected families. Identification of the disease gene itself allows the characterization of the protein involved and direct diagnosis at DNA and protein level, thus leading to a greater understanding of the molecular pathology of neurogenetic disorders.

Chromosome Mapping↗
PubMed1987

Multipoint gene mapping using seriation. I. General methods.

Initial and accurate inference of locus order and estimates of interlocus distances and interference can be obtained using seriation techniques. The analysis requires a matrix of recombination values that can be estimated by standard pairwise linkage analysis. This allows combination of results from individual investigators without reanalysis of basic pedigree material. Seriation can be performed without the use of a computer.

Chromosome Mapping↗
PubMed1987

The use of map functions in multipoint mapping.

The analysis of multipoint data in humans involves detection of linkage, inferences about order, and estimation of map lengths. In order to calculate likelihoods, it is necessary to have predictive formulas for multiple recombination frequencies. In the present study the Markovian assumption of Morton and MacLean is generalized to give predictive formulas for multiple-region recombination using realistic map functions. The best-fitting map functions have been determined by fitting the nine-locus data of Morgan et al. and the seven-locus data of Weinstein on the Drosophila X chromosome. Two map functions fit the data better than other published functions: that of Rao et al. with a map parameter of P = .33 and a new function suggested in the present paper. The close agreement of the estimate of the mapping parameter with a previous estimate inferred from human male meiosis suggests that the map function is robust. A further improvement in the fit to the data can be obtained by the addition of a second parameter to reduce the expected number of multiple recombinants. By comparison with the map functions recommended in the present paper, the assumption of no interference gives a poor fit to the data.

Chromosome Mapping↗