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Biomedical subjects

D Patterson

Publications and source records attributed to D Patterson.

At least 109 records · Page 6Linked to original sources
PubMed1989

Aging: effect on hepatic metabolism and transport of folate in the rat.

Effects of aging on hepatic folate metabolism and transport were assessed in male Fisher 344 rats. Total serum and hepatic folate levels were measured. Hepatic folates were measured by high-performance liquid chromatography and by Lactobacillus casei assay. Transport of 5-methyltetrahydrofolate (5-CH3-H4PteGlu) was measured in isolated hepatocytes. Serum folate declined with aging; however, neither the total folate level nor the distribution of hepatic folate coenzymes was affected by the aging process. The level of liver folate monoglutamates was not significantly different in any group. The initial rate of uptake of 5-CH3-H4PteGlu was significantly decreased in hepatocytes from the 24-mo-old rats, as was the ability to concentrate this folate from the medium. Aged rats maintain apparently normal levels of hepatic folates despite decreased serum levels and decreased ability to take up folates, suggesting that membrane transport of folates may not be a limiting factor in hepatic folate assimilation.

Aging↗
PubMed1989

Effects of extracorporeal shock wave lithotripsy on single chamber rate response and dual chamber pacemakers.

This study evaluated effects of extracorporeal shock wave lithotripsy on four models of Medtronic implantable cardiac pacemakers. In vitro testing consisted of: (1) unsynchronized pacemaker strapped on the patient with extracorporeal shock synchronized to the patient's native heart rate; and (2) pacemakers suspended alone in water 6 inches from the focal point, synchronizing the extracorporeal shock to pacemaker output. Unsynchronized shocks affected each model of pacemaker differently, i.e., single chamber constant rate pacemakers experienced extended periods of inhibition for more than three pacing cycles while activity-triggered rate response pacemakers exhibited rate increases to the upper rate setting. Dual chamber synchronous pacemakers exhibited intermittently a 59% decrease and a 20% increase in ventricular rate due to inhibition and triggering, respectively, from shock oversensing. Synchronized shocks did not alter the rate of single chamber constant rate pacemakers, but did cause the rate to increase to the upper rate setting for activity-triggered rate response pacemakers. The shock was synchronized to the initial atrial output from the dual chamber pacemaker and caused frequent inhibition of the ventricular stimulus when the ventricular-safety-pace (VSP) feature was programmed off. Programming VSP on reduced the incidence of ventricular inhibition resulting in near normal pacemaker operation. There was neither observable damage to pacemaker components nor spurious reprogramming of pacemaker parameters during the tests. Our studies with one manufacturer's pacemakers suggests that lithotripsy shock effects on implantable pacemakers can be tolerated provided: (1) the single chamber pacemaker is programmed to the demand constant rate modality; (2) the dual chamber pacemaker is programmed to VSP on or to the VVI mode; and (3) the pacemaker distance to the focal point is greater than 6 inches.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗
PubMed1988

Resolution of the intermediates of de novo purine biosynthesis by ion-pair reversed-phase high-performance liquid chromatography.

An ion-pair reversed-phase high-performance liquid chromotographic procedure capable of resolving twelve of the fourteen intermediates of de novo purine biosynthesis is presented. The method utilizes isocratic elution and detection by ultraviolet light absorption. Separation of all twelve intermediates can be achieved in 90 min.

Chromatography, High Pressure Liquid↗
PubMed1988

Isolation of DNA sequences on human chromosome 21 by application of a recombination-based assay to DNA from flow-sorted chromosomes.

By merging two efficient technologies, bivariate flow sorting of human metaphase chromosomes and a recombination-based assay for sequence complexity, we isolated 28 cloned DNA segments homologous to loci on human chromosome 21. Subregional mapping of these DNA segments with a somatic cell hybrid panel showed that 26 of the 28 cloned DNA sequences are distributed along the long arm of chromosome 21, while the other 2 hybridize with sequences on the short arm of both chromosome 21 and other chromosomes. This new collection of probes homologous to chromosome 21 should facilitate molecular analyses of trisomy 21 by providing DNA probes for the linkage map of chromosome 21, for studies of nondisjunction, for chromosome walking in clinically relevant subregions of chromosome 21, and for the isolation of genes on chromosome 21 following the screening of cDNA libraries.

Animals↗
PubMed1988

Mapping of bovine PRGS and PAIS genes in hybrid somatic cells: syntenic conservation with human chromosome 21.

Somatic cell genetics coupled with enzyme electrophoresis has facilitated the mapping of PRGS and PAIS genes in cattle. Individual cow-hamster hybrid cell lines established by fusion of mutant CHO cells, ade-C and ade-G, with cattle leukocytes required complementing bovine genes for PRGS and PAIS, respectively, when propogated on selective media. Homogenates of 12 PRGS+ hybrid clones and 12 PAIS+ hybrid clones retained the bovine electromorph of SOD1 while extensively segregating 14 biochemical markers of other cattle syntenic groups. Secondary cattle-hamster hybrid subclones which segregated bovine PRGS and PAIS in late passages on nonselective media concordantly segregated bovine SOD1. These data support a syntenic relationship among PRGS, PAIS, and SOD1 on cattle syntenic group U10. An interferon receptor locus, IFREC, is also syntenic with SOD1. This synteny represents an extensive conservation of bovine U10 and the "Down syndrome region" of human chromosome 21.

Animals↗
PubMed1988

Irradiation-reduced human chromosome 21 hybrids.

Rodent-human somatic cell hybrids have been constructed which contain fragments of human chromosome 21 as their only human material. This was done by irradiating rodent-human somatic cell hybrids containing a complete chromosome 21 to fragment the genome and then rescuing human GAR synthetase and various amounts of flanking chromosome 21 DNA by fusing with GAR synthetase-deficient hamster cells and selecting for growth in purine-free medium. Four irradiation-reduction hybrids were produced by this method and contain the distal, proximal, and central portions of the long arm of human chromosome 21, all centered about GAR synthetase. These irradiation-reduction hybrids were used as a panel to regionally map single-copy and individual copies of repetitive sequences. Using these hybrids along with another independently constructed hybrid, the GAR synthetase gene was mapped distal to SOD-1 and proximal to CP21G1(D21S60). Of special interest is the regional mapping of the gene for the amyloid beta-protein distal to pPW236B(D21S11) and proximal to SOD-1.

Animals↗
PubMed1988

Partial physical map of human chromosome 21.

The long arm of human chromosome 21 has been analyzed with unique sequence DNA probes, using an expanded panel of somatic cell hybrids containing defined regions of the chromosome, and both standard and pulsed field gel electrophoresis. Each member of the hybrid cell panel contains either a normal chromosome 21, or one of 11 different translocations or deletions within the long arm. Together, these now include 11 breakpoints, defining 11 long arm regions. Thirty-two unique sequence probes have been localized to these regions by standard gel electrophoresis. Analysis by pulsed field gels indicates that 27 of these identify a total of 18 Not1 restriction fragments, which together account for approximately 17 million base pairs, over half the long arm. Five physical linkage groups have been identified, as well as patterns in the distribution of unique sequences and GC-rich chromosomal regions. This information can be correlated with that obtained by other methods and contributes to the construction of a detailed physical map of this chromosome.

Chromosome Mapping↗
PubMed1988

The ETS genes on chromosome 21 are distal to the breakpoint of the acute myelogenous leukemia translocation (8;21).

The definition of the genetic linkage map of human chromosomes may be helpful in the analysis of cancer-specific chromosome abnormalities. In the translocation (8;21)(q22;q22), a nonrandom cytogenetic abnormality of acute myelogenous leukemia (AML), we previously observed the transposition of the ETS2 gene located at the 21q22 region from chromosome 21 to chromosome 8. However, no ETS2 rearrangements were detected in the DNA of t(8;21)-positive AML cells. Genetic linkage analysis has allowed us to locate the ETS2 gene relative to other loci and to establish that the breakpoint is at an approximate genetic distance of 17 cM from ETS2. When the information from the linkage map is combined with that from molecular studies, it is apparent that (a) the t(8;21) breakpoint does not affect the ETS2 gene structure or the structure of the other four loci proximal to ETS2: D21S55, D21S57, D21S17, and ERG, and ETS-related gene; and (b) the actual DNA sequence involved in the t(8;21) must reside in a 3-cM genetic region between the D21S58 and the D21S55/D21S57 loci, and remains to be identified.

Blotting, Northern↗
PubMed1988

Mapping of the gene encoding the beta-amyloid precursor protein and its relationship to the Down syndrome region of chromosome 21.

The gene encoding the beta-amyloid precursor protein has been assigned to human chromosome 21, as has a gene responsible for at least some cases of familial Alzheimer disease. Linkage studies strongly suggest that the beta-amyloid precursor protein and the product corresponding to familial Alzheimer disease are from two genes, or at least that several million base pairs of DNA separate the markers. The precise location of the beta-amyloid precursor protein gene on chromosome 21 has not yet been determined. Here we show, by using a somatic-cell/hybrid-cell mapping panel, in situ hybridization, and transverse-alternating-field electrophoresis, that the beta-amyloid precursor protein gene is located on chromosome 21 very near the 21q21/21q22 border and probably within the region of chromosome 21 that, when trisomic, results in Down syndrome.

Alzheimer Disease↗
PubMed1988

Effects of carvedilol on blood pressure in patients with mild to moderate hypertension. A dose response study.

Carvedilol 12.5, 25 and 50 mg was administered once daily for 4 weeks to patients with mild to moderate hypertension. The purpose of the study was to investigate the antihypertensive action of carvedilol when administered once daily and to investigate the pharmacokinetics of carvedilol in patients with mild to moderate hypertension. Measurable decreases in blood pressure (BP) occurred within 1 hour after the first dose. Peak decreases in supine diastolic blood pressure (DBP) were 9.0 +/- 6.8, 15.5 +/- 6.7, 14.7 +/- 10.6 and 22.5 +/- 7.6mm Hg (+/- SD) for the placebo, 12.5, 25 and 50mg carvedilol groups, respectively, and occurred between 3 and 7 hours after the dose. Administration of carvedilol once daily for 4 weeks kept supine DBP below baseline levels for 24 hours. Trough supine DBP after 4 weeks of treatment were 0.6 +/- 6.5, 7.3 +/- 7.9, 8.8 +/- 7.4 and 12.1 +/- 3.8mm Hg (+/- SD) below baseline. Serum levels of carvedilol were proportional to the dose. Peak serum levels were 39 +/- 27, 75 +/- 38 and 161 +/- 131 mu/L for carvedilol 12.5, 25 and 50mg. The kinetics of carvedilol did not change with repeated administration. Carvedilol was well tolerated; 2 patients experienced dizziness associated with postural hypotension after administration of the 50mg dose. Carvedilol 12.5, 25 and 50mg effectively reduced BP for 24 hours when administered once daily.

Adrenergic beta-Antagonists↗
PubMed1988

Use of the Candela laser in the ureter.

The Candela pulsed dye laser is safe and effective. Complications are few and related more to the ureteroscopy than to the laser. Current results in the lower ureter utilizing primarily ultrasound as a method of power lithotripsy have been excellent, and it is difficult to see how lasertripsy will improve on these. The importance of the laser is related to its small size and its flexibility. This will permit simpler access to the stone employing instruments such as small-caliber rigid ureteroscopes and small steerable flexible instruments. If these instruments can be passed without ureteral dilatation, access to the stone will be safer, and they may well extend the range of stones regularly susceptible to ureteroscopic removal.

Endoscopy↗
PubMed1988

Lactobacillus casei microbiological assay of folic acid derivatives in 96-well microtiter plates.

Microbiological assay is still widely used for estimating folic acid derivatives in serum and other biological samples. We describe here a modification of this procedure involving use of 96-well microtiter plates. This procedure, used with modern, computer-interfaced microtiter-plate readers and data-reduction software, greatly shortens the time and minimizes reagent costs for this assay. Under the conditions of our assay procedures, all folic acid derivatives tested gave equal growth response for Lactobacillus casei. Results for assays of rat liver extracts showed excellent agreement between the standard bioassay and the 96-well procedure.

Animals↗
PubMed1988

The human erg gene maps to chromosome 21, band q22: relationship to the 8; 21 translocation of acute myelogenous leukemia.

There is accumulating evidence to support that genes on chromosome 21 play an important role in the development of pathologies associated with leukemia, Down's syndrome, and Alzheimer's disease. We have previously described erg, a human gene related to the ets oncogene. In this study, we have regionally assigned the erg gene to chromosome 21q22.3 by using somatic cell hybrids and in situ hybridization analysis. In light of this chromosome assignment, the relationship of erg to the 21q translocation breakpoint characteristic of acute myelogenous leukemia (AML) was considered. By using a DNA probe that is specific for the erg gene, a panel of rodent-human cell hybrids was analyzed by the Southern technique to study specific chromosome translocations occurring in acute myeloblastic leukemia. The erg gene was found to translocate from chromosome 21 to 8 in the t(8; 21) (q22; q22), a non-random translocation found in patients with acute myelogenous leukemia of the subgroup M2 (AML-M2). The localization of the erg gene to chromosome 21q22 raises the possibility that this gene may be involved in the pathogenesis of AML-M2.

Animals↗
PubMed1987

Complete interruption of the aortic arch in a dog.

Complete interruption of the aortic arch was diagnosed by angiocardiography in a dog with exercise intolerance, a cardiac murmur, polycythemia, and cardiomegaly. The defect was accompanied by a patent ductus arteriosus, ventricular septal defect, and subaortic stenosis. The dog was euthanatized, and the clinical diagnosis was documented by gross dissection of the heart. The site of aortic interruption was between the left carotid and left subclavian arteries, which is the most common location in human beings. The similarity with the pathologic findings of interrupted aortic arch in human beings suggests a similar mechanism responsible for the abnormal cardiac morphogenesis. The defect may be confused with other cardiac anomalies that can result in exercise intolerance, polycythemia, and cardiac murmur. This defect is amenable to surgical treatment, which emphasizes the importance of a correct anatomic diagnosis in clinical patients.

Animals↗
PubMed1987

Amyloid beta protein gene: cDNA, mRNA distribution, and genetic linkage near the Alzheimer locus.

The amyloid beta protein has been identified as an important component of both cerebrovascular amyloid and amyloid plaques of Alzheimer's disease and Down syndrome. A complementary DNA for the beta protein suggests that it derives from a larger protein expressed in a variety of tissues. Overexpression of the gene in brain tissue from fetuses with Down syndrome (trisomy 21) can be explained by dosage since the locus encoding the beta protein maps to chromosome 21. Regional localization of this gene by both physical and genetic mapping places it in the vicinity of the genetic defect causing the inherited form of Alzheimer's disease.

Alzheimer Disease↗
PubMed1987

Confirmation of assignment of the human alpha 1-crystallin gene (CRYA1) to chromosome 21 with regional localization to q22.3.

The crystallins are highly conserved structural proteins universally found in the eye lens of all vertebrate species. In mammals, three immunologically distinct classes are present, alpha-, beta-, and gamma-crystallins, and each class represents a multigene family. The alpha-crystallin gene family consists of alpha 1-crystallin (CRYA1) and alpha 2-crystallin (CRYA2) genes (previously designated alpha A- and alpha B-crystallin, respectively), which show extensive sequence homology. We constructed a synthetic oligonucleotide probe of 25 bases corresponding to a specific region of the human alpha 1-crystallin gene sequence. This 25-mer probe bears little sequence homology to human alpha 2-crystallin gene and does not cross-hybridize to alpha 2-crystallin sequences in Southern blot analysis. Using this unique synthetic probe, we have demonstrated the identity of the alpha 1-crystallin gene in human genomic DNA. In addition, we have also confirmed its chromosomal location on human chromosome 21. Finally, we have regionally localized the gene to q22.3 by using both Southern blot analysis of a panel of cell hybrids containing different parts of human chromosome 21, and in situ hybridization to metaphase chromosomes. The use of synthetic oligonucleotide probes specific for individual genes should be useful in identifying and mapping members of multigene families.

Animals↗