Biomedical subjects

S A Jackson

Publications and source records attributed to S A Jackson.

At least 37 records · Page 2Linked to original sources

PubMed2000

Comparative fluorescence in situ hybridization mapping of a 431-kb Arabidopsis thaliana bacterial artificial chromosome contig reveals the role of chromosomal duplications in the expansion of the Brassica rapa genome.

Comparative genome studies are important contributors to our understanding of genome evolution. Most comparative genome studies in plants have been based on genetic mapping of homologous DNA loci in different genomes. Large-scale comparative physical mapping has been hindered by the lack of efficient and affordable techniques. We report here the adaptation of fluorescence in situ hybridization (FISH) techniques for comparative physical mapping between Arabidopsis thaliana and Brassica rapa. A set of six bacterial artificial chromosomes (BACs) representing a 431-kb contiguous region of chromosome 2 of A. thaliana was mapped on both chromosomes and DNA fibers of B. rapa. This DNA fragment has a single location in the A. thaliana genome, but hybridized to four to six B. rapa chromosomes, indicating multiple duplications in the B. rapa genome. The sizes of the fiber-FISH signals from the same BACs were not longer in B. rapa than those in A. thaliana, suggesting that this genomic region is duplicated but not expanded in the B. rapa genome. The comparative fiber-FISH mapping results support that chromosomal duplications, rather than regional expansion due to accumulation of repetitive sequences in the intergenic regions, played the major role in the evolution of the B. rapa genome.

Arabidopsis↗

PubMed2000

The relation of residential segregation to all-cause mortality: a study in black and white.

OBJECTIVES: This study investigated the influence of an aggregate measure of the social environment on racial differences in all-cause mortality. METHODS: Data from the National Longitudinal Mortality Study were analyzed. RESULTS: After adjustment for family income, age-adjusted mortality risk increased with increasing minority residential segregation among Blacks aged 25 to 44 years and non-Blacks aged 45 to 64 years. In most age/race/gender groups, the highest and lowest mortality risks occurred in the highest and lowest categories of residential segregation, respectively. CONCLUSIONS: These results suggest that minority residential segregation may influence mortality risk and underscore the traditional emphasis on the social underpinnings of disease and death.

Adult↗

PubMed1999

Digital mapping of bacterial artificial chromosomes by fluorescence in situ hybridization.

The bacterial artificial chromosome (BAC) has become the most popular tool for cloning large DNA fragments. The inserts of most BAC clones average 100-200 kilobases (kb) and molecular characterization of such large DNA fragments is a major challenge. Here we report a simple and expedient technique for physical mapping of BAC inserts. Individual BAC molecules were immobilized on glass slides coated with Poly-L-lysine. The intact circular BAC molecules were visualized by fluorescence in situ hybridization using BAC DNA as a probe. The 7.4 kb BAC vector was extended to approximately 2.44 kb per micrometer. Digitally measured linear distances can be transformed into kilobases of DNA using the extension of BAC vector as a standard calibration. We mapped DNA fragments as small as 2 kb directly on circular BAC molecules. A rice BAC clone containing both tandem and dispersed repeats was analyzed using this technique. The distribution and organization of the different repeats within the BAC insert were efficiently determined. The results showed that this technique will be especially valuable for characterizing BAC clones that contain complex repetitive DNA sequences.

Arabidopsis↗

PubMed1999

The flow experience: a Rasch analysis of Jackson's Flow State Scale.

Jackson and Marsh (1996) reported the development of a Flow State Scale (FSS) for use in sport and physical activity. The FSS contains 36 items measuring the nine dimensions of flow described by Csikszentmihalyi (1990, 1993). Jackson and Marsh reported high internal consistency estimates for the subscales and evidence for nine first-order factors and one second-order factor when confirmatory factor analytic techniques were used. The present study extended this validation work by subjecting the data from the original sample (N = 394) of elite younger athletes and a subsequent sample (N = 398) of older athletes to Rasch analysis. These Rasch analyses showed quite clearly that the flow dimensions may be conceptualised as a continuum with "autotelic experience" being experienced more readily than dimensions such as "transformation of time", a state that may only be encountered at the height of a deep flow experience. The Rasch analyses provide useful additional information about the areas of the flow continuum tapped by the items and scales of the FSS and, in so doing, help to confirm the construct validity and generalisability of the scale itself.

Adolescent↗

PubMed1998

Rice (Oryza sativa) centromeric regions consist of complex DNA.

Rice bacterial artificial chromosome clones containing centromeric DNA were isolated by using a DNA sequence (pSau3A9) that is present in the centromeres of Gramineae species. Seven distinct repetitive DNA elements were isolated from a 75-kilobase rice bacterial artificial chromosome clone. All seven DNA elements are present in every rice centromere as demonstrated by fluorescence in situ hybridization. Six of the elements are middle repetitive, and their copy numbers range from approximately 50 to approximately 300 in the rice genome. Five of these six middle repetitive DNA elements are present in all of the Gramineae species, and the other element is detected only in species within the Bambusoideae subfamily of Gramineae. All six middle repetitive DNA elements are dispersed in the centromeric regions. The seventh element, the RCS2 family, is a tandem repeat of a 168-bp sequence that is represented approximately 6,000 times in the rice genome and is detected only in Oryza species. Fiber-fluorescence in situ hybridization analysis revealed that the RCS2 family is organized into long uninterrupted arrays and resembles previously reported tandem repeats located in the centromeres of human and Arabidopsis thaliana chromosomes. We characterized a large DNA fragment derived from a plant centromere and demonstrated that rice centromeres consist of complex DNA, including both highly and middle repetitive DNA sequences.

Base Sequence↗

PubMed1998

Radiological appearances of lymphomas arising from mucosa-associated lymphoid tissue (MALT) in the lung.

We review the radiological findings in 13 patients with histologically proven (n = 10) or clinically diagnosed (n = 3) lymphomas arising in mucosa-associated lymphoid tissue (MALT) of the lung. These rare B-cell lymphomas typically follow an indolent course, and many cases are still being incorrectly described in current radiological literature under the term pseudolymphoma. The patients frequently give a history of autoimmune disease involving the affected organ, and involvement of another mucosal site as part of a disseminated MALT lymphoma, is common. The radiographic patterns of pulmonary parenchymal involvement in lung MALT lymphomas have been reviewed, and correlation made with their clinical behaviour.

Adult↗

PubMed1998

The role of cadherin endocytosis in endothelial barrier regulation: involvement of protein kinase C and actin-cadherin interactions.

We have previously reported that exposure of endothelial monolayers to low (0.12 mM) extracellular calcium significantly decreased the endothelial solute barrier, and that this effect was reversed by restoring 'normal' (1.2 mM) calcium (1). This effect was shown to be dependent on cadherins, however the molecular mechanisms through which barrier was altered by low calcium were not characterized. Here we investigated the mechanism of increased endothelial permeability produced by low calcium exposure. Endothelial permeability was significantly increased by exposure to low (0.12 mM) calcium; this effect was attenuated by pre-treatment with the protein kinase C (PKC) inhibitor, staurosporine (2 x 10(-7) M) for 30 min. Cell border retraction and gap formation produced by low calcium was also prevented by staurosporine. Treatment of monolayers with 0.12 mM calcium also stimulated the endocytosis of endothelial cadherins. This low calcium mediated cadherin endocytosis was also prevented by pretreatment with staurosporine. Low calcium mediated endocytosis was also prevented by the actin filament toxin, cytochalasin D (1 ug/ml, 30 min). We conclude that the mechanism of low calcium mediated loss of endothelial barrier function is mediated in part by a PKC dependent endocytosis of endothelial cadherins, which may involve interactions with the actin cytoskeleton. Physiological regulation of the in vivo endothelial barrier may also involve PKC dependent-actin mediated endocytosis of cadherin junctional elements.

Actins↗

PubMed1998

Retrotransposon-related DNA sequences in the centromeres of grass chromosomes.

Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.

Amino Acid Sequence↗

PubMed1998

Application of fiber-FISH in physical mapping of Arabidopsis thaliana.

Arabidopsis thaliana has become a model plant species for genetic studies because of its small genome and short juvenility period. However, the small chromosomes of this species are not suitable for classical cytogenetic studies. Here we demonstrate that the fluorescence in situ hybridization (FISH) technique using extended DNA fibers can be a powerful tool in the physical mapping of the A. thaliana genome. Using a refined fiber-FISH technique we were able to measure DNA clusters as long as 1.71 Mb, more than 1% of the A. thaliana genome. Several small DNA loci, including the telomeres and a dispersed repetititve DNA sequence, mi167, were also analyzed with this technique. The results show that without known adjacent DNA markers such small DNA loci cannot be mapped precisely using fiber-FISH. One of the most difficult obstacles in physical mapping by contig assembly is closing the gaps that are present between adjacent contigs. Currently available molecular techniques are not sufficient to accurately estimate the physical sizes of these gaps. We isolated bacterial artificial chromosome (BAC) clones bordering gaps 2 and 3 on the physical contig map of A. thaliana chromosome II. The BAC clones were used in fiber-FISH analysis and the physical sizes of the two gaps were estimated as 31 kb and more than 500 kb, respectively. Thus, we have demonstrated that fiber-FISH is an efficient technique for determining the physical size of gaps on molecular contig maps.

Arabidopsis↗

PubMed1997

Dog-bite induced sepsis: a report of four cases.

Occasionally, a dog-bite is complicated by a systemic overwhelming infection. We report four consecutive patients who were admitted to our intensive care unit because of sepsis syndrome following dog-bites. The history of these patients did not reveal any immunocompromising conditions. Capnocytophaga canimorsus (C. canimorsus) was cultured from the blood culture of 2 patients. Our data illustrate that in patients with lack of immune-deficiency severe sepsis may develop.

Animals↗

PubMed1997

Rhythm and language in children with moderate learning difficulties.

The relationship between rhythmic ability, syllabic structure in the production of single words and two-word phrases, and overall language ability was assessed in a group of 22 children, aged between 4;0-8;0, with moderate learning difficulties in the absence of gross sensory, motor or behavioural difficulties. It was predicted that rhythmic ability would correlate significantly both with syllable production and with overall language attainment. We further predicted that clapping to highlight syllable number and rhythm would significantly improve syllable production. The first hypothesis was supported in so far as rhythmic ability correlated significantly with syllable production. However, rhythmic ability did not correlate significantly with overall language attainment. The second hypothesis was supported. The results are discussed in terms of their theoretical implications for our understanding of language development in children with moderate learning difficulties and in terms of their practical implications for therapy.

Child↗

PubMed1997

Postoperative management of hypothermia of intra-operative origin--experience with a forced-air convective warming device.

Hypothermia develops during the intra-operative period partly as a result of disordered thermoregulation induced by anaesthesia, and partly because of the nature of the operation or injury and the surgical environment. Both the hypothermic state and the consequences of physiological attempts to return the core temperature to normal, which take place during the postoperative period, are associated with non-beneficial effects. Attempts to prevent an intra-operative decline in core temperature are a part of anaesthesia management. However, most of the traditional options available are inefficient or ineffective, especially if used as a single intervention and particularly in adults. This study evaluates the performance of a new device, the forced-air convective warmer, in the management of the postoperative hypothermic state. Results show that the device made a significant difference to the thermal state of a group of hypothermic postoperative patients when compared with a hypothermic control group, but only if used for at least 2 hours after the operation.

Adolescent↗

PubMed1996

Toward a conceptual understanding of the flow experience in elite athletes.

An in-depth investigation into flow state was conducted in order to understand how this optimal state is experienced by elite athletes. Twenty-eight elite-level athletes, representing 7 sports, were interviewed on their perceptions of flow state during performance of their sport. Csikszentmihalyi's (1990) model of the flow state was examined for its applicability to elite athletes. Correspondence was found between the dimensions of flow, as described by Csikszentmihalyi (1990), and the athletes' descriptions of their experience of flow; some dimensions received greater support through the qualitative analysis of the athletes' descriptions than did other dimensions. Those dimensions of flow most represented across the group's data were the autotelic experience of flow, total concentration on the task at hand, merging of action and awareness, and the paradox of control. The analyses provided a detailed, sport-specific picture of flow state in elite athletes.

Adolescent↗

PubMed1996

Does post-laparoscopy pain relate to residual carbon dioxide?

We studied 20 day case gynaecological laparoscopy patients, who had an erect chest X ray taken before discharge. Patients were telephoned the next day for a semi-structured interview. Particular note was made of shoulder tip pain and pain relieved by changing posture. The X ray was analysed for measurements of the length of arc and height of the gas bubble under each hemi-diaphragm, from which an estimation of bubble volume was also made. We found statistically significant correlations between both the length of arc (p = 0.005) and volume of gas bubble (p = 0.008) on the right side, with the pain score. Residual gas can be a prominent cause of post-laparoscopy pain.

Carbon Dioxide↗

PubMed1995

Platelet GPIIb/IIIa receptor occupancy studies using a novel fluoresceinated cyclic Arg-Gly-Asp peptide.

DMP 728 is a potent and specific platelet GPIIb/IIIa antagonist. Like all GPIIb/IIIa antagonists, DMP 728 has a steep dose-response relationship in inhibiting platelet aggregation. In this study the relationships between receptor occupancy, platelet aggregation and bleeding time was determined in anesthetized dogs after intravenous infusion of DMP 728 (0.01 and 0.1 mg/kg/2h). Receptor occupancy was determined by flow cytometry using XL086, a novel fluorescent cyclic RGD peptide that binds to GPIIb/IIIa with high specificity and affinity (kd approximately 55 nM). Mean number of GPIIb/IIIa as determined by flow cytometric assay was approximately 53,8000 and 79,000 on unactivated and ADP-activated platelets respectively. After DMP 728 intravenous infusion, there was a dose- and time-dependent increase in receptor occupancy, inhibition of platelet aggregation and bleeding time. The two methods of receptor occupancy determination correlate with each other with an r2 = 0.78. The present data suggest that blockade of only 40-60% (approximately 40,000 receptors) of the total platelet GPIIb/IIIa was required to achieve > 90% inhibition of platelet aggregation and > 15 min bleeding time. Our results showed the potential clinical utility of this approach in the study of GPIIb/IIIa dose-response relationship.

Amino Acid Sequence↗

PubMed1995

Nuclear-cytoplasmic translocations of protein p26 during aerobic-anoxic transitions in embryos of Artemia franciscana.

Embryos of the crustacean Artemia franciscana survive continuous anoxia for periods of years, during which their metabolism comes to a reversible stand-still. A question of some interest concerns the maintenance of cellular integrity in the absence of biosynthesis and an ongoing energy metabolism. The present paper continues previous work on an abundant protein (p26) that undergoes extensive intracellular translocation during aerobic-anoxic transitions, exhibits several characteristics of stress proteins, and might be involved in metabolic regulation during aerobic-anoxic transitions. Since it has been established that intracellular pH (pHi) plays a major role in aerobic-anoxic transitions in this system we examined the pH-dependence of nuclear-cytoplasmic translocations of p26. In unincubated and aerobic-incubated embryos (pHi > or = 7.9) p26 was located in the "soluble" fraction, whereas in anoxic embryos (pH about 6.3) roughly 50% was translocated into the nucleus as shown by immunocolloidal gold electron microscopy. These nuclear translocations also took place in vitro, simply by manipulating buffer pH in a physiologically appropriate fashion. Immunostaining of Western blots prepared after two-dimensional electrophoresis revealed several isoforms of native p26. The isoelectric point of the major isoform was 7.10 +/- 0.05, a value close to the pH at which p26 translocation into the nucleus was first initiated in vitro. 31P-NMR measurements indicated that pHi was maintained at acidic levels (about 6.3) during prolonged anoxia. We also found that pHi of hydrated (0 degree C) but otherwise unincubated embryos was alkaline, allowing for rapid resumption of metabolism under permissive conditions. The significance of these pH-dependent translocations of p26 is discussed.

Aerobiosis↗

PubMed1994

Extensive intracellular translocations of a major protein accompany anoxia in embryos of Artemia franciscana.

Cells of encysted gastrula embryos of the crustacean Artemia franciscana exhibit extraordinary stability during prolonged anoxia. We find that they contain an abundant protein (referred to as "26-kDa protein") that undergoes translocation to the nucleus during anoxia. The reverse translocation rapidly occurs when anoxic embryos are returned to aerobic conditions. A similar translocation appears to take place in embryos exposed to 42 degrees C aerobic heat shock and prolonged exposure to low temperature (0-2 degrees C), and in diapause embryos. Gel filtration and Western immunoblotting indicate that the 26-kDa protein is translocated to other cellular compartments and may also be associated with a wide variety of "soluble" proteins during anoxia. This protein makes up roughly 15% of the total nonyolk embryo protein and is, by far, most abundant in the encysted embryo stage of the life cycle. The hypothesis is advanced that the 26-kDa protein may play the role of a metabolic regulator and/or a protective molecular chaperone during prolonged anoxia and other forms of stress.

Aerobiosis↗

PubMed1994

Multiple cavitating pulmonary lesions in non-Hodgkin's lymphoma.

We report two patients with multiple cavitating lung lesions caused by large cell non-Hodgkin's lymphoma. This pattern of disease has rarely been reported in non-Hodgkin's lymphoma and is more commonly described in Hodgkin's disease. The patterns of pulmonary parenchymal involvement in non-Hodgkin's lymphoma are reviewed with particular reference to cavitary lesions.

Adult↗