PubMed Health⌕ Search

Biomedical subjects

D Atkinson

Publications and source records attributed to D Atkinson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Cryoelectron microscopy of low density lipoprotein in vitreous ice.

In this report, images of low density lipoprotein (LDL) in vitreous ice at approximately 30 A resolution are presented. These images show that LDL is a quasi-spherical particle, approximately 220-240 A in diameter, with a region of low density (lipid) surrounded by a ring (in projection) of high density believed to represent apolipoprotein B-100. This ring is seen to be composed of four or five (depending on view) large regions of high density material that may represent protein superdomains. Analysis of LDL images obtained at slightly higher magnification reveals that areas of somewhat lower density connect these regions, in some cases crossing the projectional interiors of the LDL particles. Preliminary image analysis of LDL covalently labeled at Cys3734 and Cys4190 with 1.4-nm Nanogold clusters demonstrates that this methodology will provide an important site-specific marker in studies designed to map the organization of apoB at the surface of LDL.

Centrifugation, Density Gradient↗
PubMed1995

Hepatic cryosurgery in the treatment of unresectable metastases.

The treatment of unresectable hepatic metastases has generally been limited to systemic or intra-arterial chemotherapy. Cryosurgery has the advantage of potentially ablating such unresectable tumours. From November 1987 to August 1994, 140 patients underwent 155 procedures using hepatic cryosurgery with and without resection for documented metastatic disease. Intra-operative ultrasound was used for monitoring the freezing zone. The tumours were frozen using liquid nitrogen cooled to -196 degrees C for 15 min. The median number of lesions treated was three. Median hospital stay was 10 days. The operative mortality was 4%. Complications included coagulopathy, hypothermia, myoglobinuria, pleural effusions, ATN and infection. The median survival for all patients was 22 months. Of those patients followed for more than 2 years, the median survival was 25 months. Of the 65 patients that are still alive, the median follow-up is 27 months.

Adolescent↗
PubMed1995

Arbuscular mycorrhizal induced changes to plant growth and root system morphology in Prunus cerasifera.

We compared root system morphogenesis of micropropogated transplants of Prunus cerasifera L. inoculated with either of the arbuscular mycorrhizal (AM) fungi Glomus mosseae or Glomus intraradices or with the ericoid mycorrhizal species Hymenoscyphus ericae. All plants were grown in sand culture, irrigated with a nutrient solution that included a soluble source of phosphorus, for 75 days after transplanting. Arbuscular mycorrhizal colonization increased both the survival and growth (by over 100%) of transplants compared with either uninoculated controls or transplants inoculated with H. ericae. Arbuscular mycorrhizal colonization increased root, stem and leaf weights, leaf area, root length and specific leaf area, and it decreased root length/leaf area ratio, root/shoot weight ratio and specific root length. Both uptake of phosphorus and its concentration in leaves were increased by AM infection, although the time course of the relationships between intensity of AM infection and P nutrition were complex and suggested a role for factors other than nutrition. The time course for the development of infection varied. It was most rapid with G. mosseae, but it was ultimately higher with G. intraradices. None of the treatments significantly affected the lengths of adventitious roots or the first-, second- or third-order laterals that developed from them. Arbuscular mycorrhizal colonization increased the intensity of branching in all root orders with the effect being most obvious on first-order lateral roots where the number of branches increased from under 100 to over 300 brances m(-1). As a result, although first-order laterals made up 55% of the root systems of control plants, the comparable value was 36% in AM-infected plants. In contrast, second-order laterals represented 25% of control root systems, but 50% of AM-colonized root systems. Glomus intraradices but not G. mosseae increased root diameter. Anatomical studies revealed no changes in the overall form of the root tip, although there were changes in the diameter of the root cap, cell numbers and cell size. Hymenoscyphus ericae increased the duration of the metaphase index. Both AM fungal treatments increased the concentrations of soluble proteins in root extracts and modified the protein profiles by the elimination and addition of protein bands detected by PAGE analysis. We conclude that AM fungal inoculation influenced processes in the root system at different levels, but not all effects were due to improved P nutrition or increased physiological age.

Journal Article↗
PubMed1995

The development of integrated public health information systems: a statement by the Joint Council of Governmental Public Health Agencies.

To truly enjoy the benefits of the information age, public health agencies at each level of government must work together to plan and implement integrated information systems that meet the needs of our dynamic profession. The Joint Council of Governmental Public Health Agencies, comprised of state and local health officials, has worked to identify the solutions to public health's information needs. Investments in integrated systems that support service delivery to clients will improve program management and enhance accountability for public funds. The ability to produce good, client-centered data will be essential as the nation's health and welfare systems change.

Data Collection↗
PubMed1994

Polymerase chain reaction heteroduplex polymorphism analysis by entangled solution capillary electrophoresis.

Heteroduplex DNA polymorphism analysis (HPA) makes use of conformational polymorphisms to alter electrophoretic mobility of fragments and can be used to detect non-restrictable loci. We have developed a novel application of entangled solution capillary electrophoresis (ESCE) to separate heteroduplex and homoduplex DNA molecules. The addition of ethidium bromide and glycerol to the free solution sieving buffer resulted in the improved peak resolution and good reproducibility. Reannealed polymerase chain reaction products could be used directly for mutation screening and with fully automated ESCE the entire HPA may be completed in less than 30 min including sample handling. This technology could provide a rapid and highly efficient way for screening rare mutations among large numbers of individuals.

Base Sequence↗
PubMed1994

Two long QT syndrome loci map to chromosomes 3 and 7 with evidence for further heterogeneity.

Cardiac arrhythmias cause sudden death in 300,000 United States citizens every year. In this study, we describe two new loci for an inherited cardiac arrhythmia, long QT syndrome (LQT). In 1991 we reported linkage of LQT to chromosome 11p15.5. In this study we demonstrate further linkage to D7S483 in nine families with a combined lod score of 19.41 and to D3S1100 in three families with a combined score of 6.72. These findings localize major LQT genes to chromosomes 7q35-36 and 3p21-24, respectively. Linkage to any known locus was excluded in three families indicating that additional heterogeneity exists. Proteins encoded by different LQT genes may interact to modulate cardiac repolarization and arrhythmia risk.

Base Sequence↗
PubMed1994

Improved MR angiography: magnetization transfer suppression with variable flip angle excitation and increased resolution.

Results at conventional magnetic resonance (MR) angiography were compared with results at MR imaging with a sequence combining optimized magnetization transfer (MT) saturation and tilted optimized nonsaturating excitation (TONE). Forty images were obtained of five healthy volunteers and five patients with known intracranial vascular abnormalities (four men and six women, aged 22-72 years). Four blinded readers found improved vessel penetration, enhanced vessel-to-background contrast, the better vessel detail in the MT saturation-TONE images than in the conventional three-dimensional time-of-flight MR angiograms.

Adult↗
PubMed1994

Supravalvular aortic stenosis associated with a deletion disrupting the elastin gene.

Supravalvular aortic stenosis (SVAS) is an inherited vascular disease that can cause heart failure and death. SVAS can be inherited as an autosomal dominant trait or as part of a developmental disorder, Williams syndrome (WS). In recent studies we presented evidence suggesting that a translocation disrupting the elastin gene caused SVAS in one family while deletions involving the entire elastin locus caused WS. In this study, pulsed-field, PCR, and Southern analyses showed that a 100-kb deletion of the 3' end of the elastin gene cosegregated with the disease in another SVAS family. DNA sequence analysis localized the breakpoint between elastin exons 27 and 28, the same region disrupted by the SVAS-associated translocation. These data indicate that mutations in the elastin gene cause SVAS and suggest that elastin exons 28-36 may encode critical domains for vascular development.

Aortic Stenosis, Subvalvular↗
PubMed1994

Magnetic resonance angiography.

Magnetic resonance (MR) angiography is a broad and expanding field. The technology of MR angiograms is evolving to produce higher spatial resolution, faster acquisition times, and reduced artifact. Rather than a straight, linear evolution, this progress is going forward in a number of areas inherent to the MR imaging process. Considerable progress has been demonstrated in such diverse areas as flow-sensitized radiofrequency pulses, reduced background signal with off-resonance pulses, improved vessel depiction with reduced echo times via improved hardware and reconstruction techniques, and improved display with more powerful computer algorithms. This review is a brief survey and comparison of available techniques for the visualization of blood vessels within the human body.

Humans↗
PubMed1994

Skin simulation for minor surgical procedures.

A simulated skin preparation is described which is made by bonding siliconized rubber to a latex foam base. This composite material, which simulates both the dermis/epidermis and subcutaneous fat, provides a realistic model which can be used to teach excision of skin lesions and a variety of suturing methods. We believe that this simulator is of value not only for surgeons in-training but also will allow general practitioners to improve their technical skills in performing minor surgical procedures.

Dermatologic Surgical Procedures↗
PubMed1993

Hepatic cryosurgery with and without the Bair Hugger.

Hypothermia is a significant clinical problem during hepatic cryosurgery, which at times causes the procedure to be halted until the patient's body temperature can be raised. This study examines the effects of the Bair Hugger (a warming device) on body temperature during hepatic cryosurgery. Twenty-eight cases of hepatic cryosurgery were performed without the Bair Hugger, while 44 cases included the Bair Hugger. The lowest mean temperature was significantly lower in the group without the Bair Hugger (34.2 degrees C vs. 35.3 degrees C; P < 0.0001). In addition, this group showed a significantly greater mean change in temperature during the procedure (1.81 degrees C vs. 0.73 degrees C; P < 0.0001). No patient in the Bair Hugger group reached the point of clinically significant hypothermia. In conclusion, the Bair Hugger is safe and very effective in regulating body temperature and it is an essential piece of equipment performing hepatic cryosurgery.

Cryosurgery↗
PubMed1993

Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome.

Williams syndrome (WS) is a developmental disorder affecting connective tissue and the central nervous system. A common feature of WS, supravalvular aortic stenosis, is also a distinct autosomal dominant disorder caused by mutations in the elastin gene. In this study, we identified hemizygosity at the elastin locus using genetic analyses in four familial and five sporadic cases of WS. Fluorescent in situ hybridization and quantitative Southern analyses confirmed these findings, demonstrating inherited and de novo deletions of the elastin gene. These data indicate that deletions involving one elastin allele cause WS and implicate elastin hemizygosity in the pathogenesis of the disease.

Adult↗
PubMed1993

Locus heterogeneity of autosomal dominant long QT syndrome.

Autosomal dominant long QT syndrome (LQT) is an inherited disorder that causes syncope and sudden death from cardiac arrhythmias. In genetic linkage studies of seven unrelated families we mapped a gene for LQT to the short arm of chromosome 11 (11p15.5), near the Harvey ras-1 gene (H ras-1). To determine if the same locus was responsible for LQT in additional families, we performed linkage studies with DNA markers from this region (H ras-1 and MUC2). Pairwise linkage analyses resulted in logarithm of odds scores of -2.64 and -5.54 for kindreds 1977 and 1756, respectively. To exclude the possibility that rare recombination events might account for these results, we performed multipoint linkage analyses using additional markers from chromosome 11p15.5 (tyrosine hydroxylase and D11S860). Multipoint analyses excluded approximately 25.5 centiMorgans of chromosome 11p15.5 in K1756 and approximately 13 centiMorgans in K1977. These data demonstrate that the LQT gene in these kindreds is not linked to H ras-1 and suggest that mutations in at least two genes can cause LQT. While the identification of locus heterogeneity of LQT will complicate genetic diagnosis, characterization of additional LQT loci will enhance our understanding of this disorder.

Chromosome Mapping↗
PubMed1993

Effects of argon laser light, alternate source light, and cyanoacrylate fuming on DNA typing of human bloodstains.

Restriction fragment length polymorphism (RFLP) profile results were obtained from deoxyribonucleic acid (DNA) isolated from human bloodstains that had been subjected to cyanoacrylate ester ("superglue") fuming, argon ion laser light and alternate light sources. All RFLP profile results obtained from treated samples were consistent with the DNA pattern from untreated bloodstains.

Argon↗