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Biomedical subjects

D Weaver

Publications and source records attributed to D Weaver.

At least 19 recordsLinked to original sources
PubMed1992

Effect of an anterior wall motion abnormality on the results of single-plane and biplane left ventriculography.

Although the biplane area-length method would be optimal for all left ventriculograms, 2 contrast injections are needed in laboratories with single-plane imaging equipment. The purpose of this study was to develop practical guidelines to identify the need for biplane left ventriculography in laboratories with single-plane equipment. From a retrospective analysis of 91 consecutive biplane ventriculograms (group 1), guidelines were identified that predicted when the ejection fraction calculated by the biplane method would differ significantly from the single-plane value. These guidelines were derived from information immediately available to the operator in the laboratory at the time of the procedure. Patients in group 1 were divided into 3 subgroups: biplane exceeding single-plane ejection fraction by greater than or equal to 0.05 (n = 20); single-plane exceeding biplane ejection fraction by greater than or equal to 0.05 (n = 14); and ejection fractions within +/- 0.04 by the 2 methods (n = 57). By multivariate analysis, the only predictor of a higher ejection fraction calculated by the biplane method was an anterior wall motion abnormality. This finding was tested prospectively in a separate group of 60 patients (group 2). Left ventriculograms in group 2 patients were stratified before analysis by the presence or absence of an anterior wall motion abnormality. In patients with anterior wall motion abnormalities, the biplane ejection fraction was greater than the single-plane value by 0.05 +/- 0.04 (range -0.03 to +0.15). In contrast, this difference in patients without anterior wall motion abnormalities was -0.01 +/- 0.04 (range -0.09 to +0.06; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1992

Marketing nursing beyond the walls.

Nurse self-actualization and service to the community are two key concepts that nurse administrators must address in developing the vision for the future direction of the nursing department. A marketing venture at a university teaching hospital demonstrated a cost-effective mechanism to meet these goals.

Adolescent↗
PubMed1991

Phenotypic inhibition of the renin-angiotensin system, emergence of the Ren-2 gene, and adaptive radiation of mice.

The renin-angiotensin system in sub-genus Mus displays unique features including duplication of the renin gene in most strains, strong expression of the second gene in submandibular gland of males, and inhibited responses to injected renin. Our findings indicate that this inhibition results from a paucity of renin substrate and is consistent with first-order kinetics. We find substrate paucity to be a feature of both sexes and all sub-species and strains of Mus irrespective of gene duplication. Attempts to increase the level of substrate in blood by intravenous injection caused marked increases in blood pressure in Mus, suggesting that substrate paucity was a phenotypic prerequisite for successful emergence of enhanced renin expression in salivary gland. We propose that these phenomena are linked to salivary "lethal factor", possibly transferred by biting, in an evolutionary sequence that has provided a major selective advantage for Mus and influenced the ecology and evolution of rodents.

Angiotensinogen↗
PubMed1991

A prospective evaluation of hepatic resection for colorectal carcinoma metastases to the liver: Gastrointestinal Tumor Study Group Protocol 6584.

We report here the results of the first multiinstitutional prospective evaluation of patients considered to have potentially resectable hepatic metastases from colorectal carcinoma. One hundred fifty-six patients were enrolled from 15 institutions. Six patients were subsequently excluded. One hundred fifty patients underwent surgery and are evaluable for analysis (median follow-up time, 3.1 years; range, 4 months to 5.1 years). Curative resection could be performed on 46% of patients (69 of 150), noncurative resection on 12% (18 of 150), while 42% were found to be unresectable (63 of 150). Thirty-day surgical mortality and morbidity rates in patients with attempted resection were 2.7% and 13%, respectively. The curative resection group was observed to have an improved median survival (37.1 months) compared with the noncurative resection group (21.2 months) and the unresectable group (16.5 months) (P less than .01). Computed tomographic (CT) scan was a poor predictor for resectability, and age was not a contraindication to curative resection. Preoperative carcinoembryonic antigen (CEA) values were also a poor predictor for resectability. However, the median CEA value 61 to 180 days postsurgery was significantly higher in unresectable patients compared with median CEA levels in noncuratively and curatively resected groups (P less than .01). Our results imply that curative resection leads to an increase in median survival. Noncurative resection provides no benefit to asymptomatic patients, since unresectable and noncurative resection groups have similar life expectancies. Longer follow-up will be needed to demonstrate the ultimate impact of curative resection on survival.

Adenocarcinoma↗
PubMed1989

Routine excretory urography in follow-up of superficial transitional cell carcinoma of bladder.

To determine cost-effective guidelines for the follow-up of patients with superficial transitional cell carcinoma of the bladder (STCCAB), we reviewed clinical histories, pathology reports, and intravenous pyelography results in 84 patients with Stage Ta or T1 disease. In 4 patients (4.8%) subsequent upper tract tumors developed with an average interval from initial presentation to the development of upper tract disease of 5.4 years. Three of these patients were treated successfully. We recommend upper tract surveillance in this group of patients with intravenous pyelography at diagnosis and every twenty-four months thereafter, or selection of those patients who are at high risk for development of upper tract disease (i.e., ureteral-vesical reflux) with voiding cystourethrography one month following each resection of tumors near a ureteral orifice. Refluxing patients should then either undergo surgical repair of their reflux or yearly pyelography.

Carcinoma, Transitional Cell↗
PubMed1988

Regional creatine kinase, adenylate kinase, and lactate dehydrogenase in normal canine brain.

Following acute stroke, creatine kinase and other enzymes are released into the cerebrospinal fluid and blood from injured brain tissue. To determine whether regional differences in brain enzyme activity might exist and therefore affect the amount of enzyme released, we quantified the levels of creatine kinase, adenylate kinase, and lactate dehydrogenase in 12 regions of normal canine brain (n = 4). Adenylate kinase activity varied the least among regions (49 +/- 7 units/g), followed by lactate dehydrogenase activity (122 +/- 28 units/g). The pattern for both adenylate kinase and lactate dehydrogenase was higher activity in predominantly gray matter areas, lower activity in white matter, and intermediate activity in mixed regions. The distribution of creatine kinase brain isoenzyme and mitochondrial creatine kinase in canine brain was less predictable, showing wider variations among regions (isoenzyme, 462 +/- 116 units/g; mitochondrial, 42 +/- 20 units/g). Even cerebral gray matter demonstrated substantial regional variations in creatine kinase brain isoenzyme, ranging from 606 units/g in the parietal cortex to 329 units/g in the temporal cortex. We conclude that the content of creatine kinase brain isoenzyme varies more than twofold among areas of brain. This regional variation may be important in the interpretation of creatine kinase brain isoenzyme measurements in cerebrospinal fluid and serum used to assess neurologic injury following stroke.

Adenylate Kinase↗
PubMed1988

Flow cytometric DNA analysis of colon adenocarcinomas: a comparative study of preparatory techniques.

DNA quantitation of solid tumors requires either nuclear extraction or disaggregation into single cells for flow cytometric (FCM) analysis. We investigated methods for disaggregating colon carcinomas comparing mechanical and enzymatic techniques in fresh tumors and compared these to extraction of nuclei from paraffin blocks. Mechanical dissociation resulted in the highest yield of tumor cells, especially tumor cells with abnormal DNA content. In addition, mechanically disaggregated intact cells, particularly when dual labeled with cytokeratin, produced optimum DNA histograms. Cytokeratin staining allowed gating on epithelial cell populations and excluded contaminating diploid inflammatory and stromal cells, improving our ability to calculate synthesis phase fractions (SpF). Human colon tumor nuclei extracted from paraffin-embedded tissue resulted in greater variation of DNA histograms and less sensitivity in identifying aneuploid cells compared to mechanically dissociated intact cells from fresh tumors. The quality of the histograms and the ability to identify aneuploid cell populations were improved by modifying the standard "Hedley" technique by additional enzyme incubation. Mechanical dissociation of fresh tumors was the preferred technique for FCM DNA analysis. Nuclear extraction from paraffin blocks resulted in some loss of sensitivity in identifying aneuploid cell lines and decreased ability to measure SpF.

Adenocarcinoma↗
PubMed1987

Aromatase inhibition by 5-substituted pyrimidines and dihydropyrimidines.

The inhibition of estrogen biosynthesis has been suggested to be an effective treatment of hormone-dependent diseases, particularly breast cancer. Several series of 5-substituted pyrimidine derivatives have been synthesized and tested for their ability to inhibit the enzyme aromatase (estrogen synthetase). Compounds were evaluated in an in vitro assay that measured the inhibition of rat ovarian microsomal aromatase activity. Greatest inhibitory activity was achieved in the cases of diarylpyrimidinemethanols and diarylpyrimidinyl methanes which were substituted in the 4- and 4'-positions with electron-withdrawing substituents, particularly Cl.

Animals↗
PubMed1987

B lymphocyte-specific protein binding near an immunoglobulin kappa-chain gene J segment.

Nuclear extracts from pre-B and B cell lines contain a nuclear DNA binding protein (kappa locus protein, KLP) that specifically recognizes a DNA sequence in the immunoglobulin kappa light chain joining (J) segment gene region. KLP is not observed in mature B cells, T cells, or nonlymphoid cell types. Two tandem binding sites for KLP designated KI and KII have been identified by methylation interference analysis to be immediately proximal to the J kappa 1 nonamer-heptamer recognition sequences and separated by 38 base pairs from each other. Fragments of DNA containing KI and KII sites compete for binding to KLP, and both protein-DNA complexes have the same electrophoretic mobility. Other flanking sequences of immunoglobulin gene fragments do not bind to KLP. The position of KLP-DNA binding and its tissue-specific expression suggest that it may be involved in the regulation of lymphoid gene DNA rearrangements by targeting recombinase to the kappa-chain gene region.

Animals↗
PubMed1986

Altered repertoire of endogenous immunoglobulin gene expression in transgenic mice containing a rearranged mu heavy chain gene.

C57BL/6 mice transgenic for a mu heavy chain gene, the VDJ region of which came from the BALB/c hybridoma 17.2.25, expressed high levels of antibody carrying determinants specific for the transgene (idiotypes). The individual antibodies made by hybridomas from transgenic mice, however, were generally encoded by endogenous genes; in most cases the transgene was present but not expressed. The endogenous, idiotype-positive antibodies had heavy chains that were notable for the high frequencies of JH4 (as in the transgene) and VH segments from the VH81X family (unrelated to the transgene). The expression of endogenous genes mimicking the idiotype of the transgene suggests that a rearranged gene introduced into the germ line can activate powerful cellular regulatory influences.

Animals↗
PubMed1986

Effect of pleurotomy on pulmonary function after median sternotomy.

To determine whether pleurotomy during median sternotomy worsens postoperative pulmonary function, patients whose pleurae remained intact (N = 7) were compared with those whose pleural spaces were entered during median sternotomy (N = 31). Thirty-eight adults performed spirometry and N2 washout to determine functional residual capacity preoperatively and 2, 24, 48, and 72 hours after extubation. Two mediastinal drainage tubes were placed in every patient; no pleural drainage tubes were inserted. Chest roentgenograms were performed preoperatively and 24 and 72 hours after extubation. Preoperatively, functional residual capacity, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC did not differ between groups. Postoperatively, in all patients developed a restrictive pulmonary defect, but mean functional residual capacity, FVC, FEV1 and FEV1/FVC did not differ between groups. In contrast to earlier reports, entering the pleural space did not worsen the restrictive pulmonary defect that results from median sternotomy when direct pleural drainage was avoided.

Adult↗
PubMed1986

Captopril antagonizes the hypotensive action of atrial natriuretic peptide in the anaesthetized rat.

Atrial natriuretic peptide (8-33; ANP) caused a prolonged hypotensive response following intravenous injection in anaesthetized rats. This response was abolished by captopril treatment and restored by concomitant angiotensin II infusion. These results suggest that ANP exerts its hypotensive action in the anaesthetized rat by the antagonism of the vasoconstrictor action of endogenous angiotensin II.

Anesthesia↗
PubMed1985

A transgenic immunoglobulin mu gene prevents rearrangement of endogenous genes.

Transgenic mice containing a microinjected rearranged immunoglobulin (Ig) mu heavy chain gene were examined for the effects on DNA rearrangement of the endogenous Ig genes. Abelson murine leukemia virus (A-MuLV) cell lines were isolated from pre-B cells of transgenic mice and of normal littermates. Microinjected mu gene RNA and a mu heavy chain protein were synthesized in every transgenic A-MuLV cell line. Only 10% of normal mouse A-MuLV transformants synthesized mu protein. A germ-line JH allele was observed in 40% of the transgenic lines, demonstrating that the block to endogenous Ig DNA rearrangement occurred at the first step of heavy chain DNA joining. All alleles were rearranged in normal mouse A-MuLV lines. Germline JH alleles were also detected in 10% of the transgenic hybridomas derived from proliferating B cells. Our results support a model of active prevention of rearrangement by the product of successfully rearranged mu genes.

Abelson murine leukemia virus↗