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Biomedical subjects

S Moon

Publications and source records attributed to S Moon.

At least 19 recordsLinked to original sources
PubMed2006

Nuclear isomers in superheavy elements as stepping stones towards the island of stability.

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the 'island of stability'; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons--the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

Journal Article↗
PubMed2005

Plasma conditions for improved energy coupling into the gain region of the Ni-like Pd transient collisional x-ray laser.

We have directly probed the conditions in which the Ni-like Pd transient collisional x-ray laser is generated and propagates by measuring the near-field image and by utilizing picosecond resolution soft x-ray laser interferometry of the preformed Pd plasma gain medium. The electron density and gain region of the plasma have been determined experimentally and are found to be in good agreement with simulations. We observe a strong dependence of the laser pump-gain medium coupling on the laser pump parameters. The most efficient coupling occurs with the formation of lower density gradients in the preformed plasma and when the duration of the main heating pulse is comparable to the gain lifetime (approximately 10 ps for mid- Z Ni-like schemes). This increases the output intensity by more than an order of magnitude relative to the commonly utilized case where the same pumping energy is delivered within a shorter heating pulse duration (<3 ps) . In contrast, the higher intensity heating pulses are observed to be absorbed at higher electron densities and in regions where steep density gradients limit the effective length of the gain medium.

Journal Article↗
PubMed2005

Determination of environmental factors influencing methane oxidation in a sandy landfill cover soil.

It is advantageous to use coarse soils as landfill cover because they allow better aeration of the biologically active zone. In this study, therefore, patterns of methane oxidation were investigated under various environmental conditions including soil moisture content, temperature, and the addition of NH4+ in a sandy landfill cover soil. The kinetics of CH4 oxidation was also studied at different moisture contents and temperatures. Soil moisture content of 10% (wt/wt) resulted in the maximum CH4 oxidation rate (19.2-22.4 nmol gsoil DW(-1) min(-1)). A Vmax value was not significantly different when the moisture content was more than 10%, but a Km value increased from 5.23 to 75.24 microM as the moisture content increased. The ratio of Vmax to Km was the highest at 10% moisture content. The CH4 oxidation rate increased as the incubation temperature increased, and Q10 values and optimum temperature were determined to be 2.57-2.69 and 30 degrees C, respectively. Both Vmax and Km values decreased at the temperatures below and above 30 degrees C. The addition of various levels of NH4+ resulted in increased or decreased CH4 oxidation rates, however, the initiation of appreciable CH4 oxidation was delayed with increasing amounts of NH4+ application in all samples tested. Among the environmental variables tested, moisture content control seems to be the most important and an efficient means of managing methane oxidation when sandy soils are used in landfill cover.

Bacteria, Anaerobic↗
PubMed2002

Picosecond x-ray laser interferometry of dense plasmas.

We present the first results from picosecond interferometry of dense laser-produced plasmas using a soft x-ray laser. The picosecond duration and short wavelength of the 14.7 nm Ni-like Pd laser mitigates effects associated with motion blurring and refraction through millimeter-scale plasmas. This enables direct measurement of the electron-density profile to within 10 microm of the target surface. A series of high-quality two-dimensional (2D) density measurements provide unambiguous characterization of the time evolution in a fast-evolving plasma suitable for validation of existing 1D and 2D hydrodynamic codes.

Journal Article↗
PubMed2001

A novel fibroblast growth factor receptor-5 preferentially expressed in the pancreas(1).

Using the polymerase chain reaction on human embryonic cDNAs, we isolated a cDNA encoding a novel 504 amino acid protein, termed fibroblast growth factor receptor (FGFR)-5, which is highly homologous to known FGFRs. The NH(2)-terminal portion of FGFR5 contains a putative secretory signal sequence, three typical immunoglobulin-like domains, six cysteines, and an acidic box, but no HAV motif. The COOH-terminal portion of FGFR5 contains one transmembrane domain but no intracellular kinase domain. Recombinant FGFR5 expressed in COS-7 cells is not secreted, but recombinant truncated FGFR5 lacking the predicted transmembrane domain is secreted. Acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) do not bind to FGFR5. Among 23 adult human tissues, FGFR5 mRNA is preferentially expressed in the pancreas. These results suggest that FGFR5 may provide a binding site for some other fibroblast growth factors and may regulate some pancreatic function.

Amino Acid Sequence↗
PubMed2001

Exposure to endosulfan in farmers: two case studies.

BACKGROUND: Endosulfan is not a restricted use organochlorine insecticide and is currently under re-registration review. In 1993, one confirmed case and one possible case of endosulfan poisoning in agricultural workers occurred in two southeastern states. METHODS: Two cases of suspected endosulfan poisoning were investigated utilizing record reviews, blood samples, a site visit, and clothing analysis. RESULTS: Case 1 was fatal; Case 2 resulted in permanent neurological impairment. Additionally, Case 1 mixed and applied two less toxic pesticides, acephate and maleic hydrazide to tobacco plants. Both farm owners had ample opportunity for endosulfan exposure while mixing concentrated endosulfan with water and applying the solution to tobacco with boom sprayers pulled by tractors. CONCLUSIONS: Estimates of the absorbed dose of endosulfan were not available because methods to determine actual personal exposure that would be found in fat or tissue samples were not used. Health and safety issues associated with endosulfan require a closer examination. A cooperative multi-disciplinary approach to providing timely accurate education is needed to prevent pesticide poisonings.

Adult↗
PubMed2000

No objective benefit from steroids inhaled via a spacer in infants recovering from bronchiolitis.

A double-blind randomized placebo-controlled trial was conducted to investigate the efficacy of 3 months' inhaled steroids delivered via a spacer device with face mask attachment to infants recovering from bronchiolitis. Forty-eight previously healthy infants recovering from their first documented episode of acute bronchiolitis were randomized to receive 150 microg fluticasone propionate (FP) b.i.d. or placebo delivered via the Babyhaler spacer. Longitudinal assessments were performed on seven occasions over 1 yr based on symptom diaries and health records, clinical examinations, overnight cough recordings and oxygen saturation readings. Lung function was measured 6 months after hospital discharge. Forty-three infants completed the trial (FP 21, placebo 22). There were no significant differences in the three objective end-points measured, recorded night cough, oxygen saturation and lung function test results. Symptom scores were low in both the FP and placebo groups with the absence of (0) or mild (1) symptoms > or =90% of the trial days. No statistical differences in symptom frequency, use of rescue respiratory medications or hospital admissions between treatment groups were found throughout the trial or follow-up periods. In conclusion, the use of inhaled fluticasone propionate in infants recovering from acute bronchiolitis cannot be recommended.

Administration, Inhalation↗
PubMed2000

The nutrition transition in South Korea.

BACKGROUND: An accelerating shift from infectious to noncommunicable diseases and concurrent shifts in diet, activity, and body composition are universal trends but are especially apparent in middle- and lower-income countries. A unique nutrition transition has occurred in South Korea, a country that modernized earlier than most Asian countries did. OBJECTIVE: The purpose of this analysis was to describe the South Korean nutrition transition, focusing on specific features that other countries might follow to retain the healthful elements of their traditional diets. DESIGN: We used secondary data on economics, dietary intake, anthropometry, and causes of death, including a series of comparable nationally representative dietary surveys (the National Nutrition Survey). RESULTS: The structure of South Korea's economy, along with the country's dietary and disease patterns, began an accelerated shift in the 1970s. Major dietary changes included a large increase in the consumption of animal food products and a fall in total cereal intake. Uniquely, the amount and rate of increase in fat intake have remained low in South Korea. South Korea also has a relatively low prevalence of obesity compared with other Asian countries with similar or much lower incomes. CONCLUSIONS: The nutrition transition in South Korea is unique. National efforts to retain elements of the traditional diet are thought to have shaped this transition in South Korea in the midst of rapid economic growth and the introduction of Western culture.

Adolescent↗
PubMed1999

Iodine content of human milk and dietary iodine intake of Korean lactating mothers.

Korea's food culture includes the consumption of seaweed, which is abundant and has a high iodine content. Because it is customary to serve seaweed soup to new mothers, the consumption of seaweed increases dramatically when a woman is lactating. The present study was undertaken for the purpose of determining the iodine content in human milk of Korean lactating mothers according to dietary iodine intake. The iodine content of human milk and dietary iodine intake from 50 lactating mothers were analyzed at 2 to 5 days and at 4 weeks postpartum. The dietary iodine intake was assessed by the 24-hour recall method. The iodine content in human milk was analyzed by neutron activation analysis (NAA). The average daily iodine intake of lactating mothers was 2744 micrograms at 2 to 5 days postpartum, decreasing significantly to 1295 micrograms at 4 weeks postpartum. The major sources of iodine were seaweed (87%) and cows' milk (7%). The average iodine content in colostrum and mature milk was 2170 micrograms/l and 892 micrograms/l, respectively. There was a significant reduction in the levels of iodine in human milk depending on the lactation period. A significant correlation between maternal iodine intake and iodine content of human milk was observed (P < 0.0001). The frequency of seaweed soup intake in lactating mothers seems to be a modifying factor in the iodine intake level and the iodine content in human milk. The level of dietary iodine intake and the iodine content of breast milk of Korean lactating mothers is found to be much higher than in other countries.

Adult↗
PubMed1997

Always single and single again women: a qualitative study.

What is it like to be a single woman today? Are the experiences of women who have always been single different from those who find themselves single again after having been married? How can family therapists promote the development of single women both individually and relationally? The purpose of this phenomenological, multiple-case study was to investigate perceptions of being single among heterosexual single women between the ages of 30 and 65. Nine focus group interviews and a semistructured, mailed questionnaire were used to collect the data. Constant comparative analyses were used to develop the findings. The findings were organized around the most salient theme that emerged from the analyses: single women have unresolved or unrecognized ambivalences about being single. This overarching theme was supported by three subassertions: (a) single women are aware of both the advantages and the drawbacks of being single; (b) single women are ambivalent about the reasons for their singleness; (c) although content with being single, many women simultaneously experience feelings of loss and grief. Implications for the clinical practice of family therapy and future research on single women are discussed.

Adult↗
PubMed1997

Most basal I(SC) in Calu-3 human airway cells is bicarbonate-dependent Cl- secretion.

Serous cells secrete antibiotic-rich fluid, but secretion is impaired in cystic fibrosis. We are investigating Calu-3 cells as a serous cell model. Basal short-circuit current (I[SC]) in Calu-3 cells grown at air interface had a basal I(SC) approximately six times larger than submerged cultures (69 +/- 22 vs. 11 +/- 10 microA/cm2). Basal I(SC) in either condition was reduced only 7 +/- 5% by bumetanide and was unaffected by apical amiloride, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), or calixarene but was reduced 77 +/- 18% by N-phenylanthranilic acid. Three transport mechanisms accounted for almost all basal I(SC). The largest component is HCO3(-)-dependent Cl- secretion. Replacement of Krebs-Henseleit solution with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered solution and changing gassing from 95% O2-5% CO2 to air reduced the basal I(SC) by 61 +/- 10%. Acetazolamide decreased basal I(SC) by 33 +/- 6%, whereas acetazolamide + basolateral DNDS eliminated 42-58% of the bumetanide-insensitive basal I(SC). Neither DNDS nor acetazolamide had any effect when applied in HCO3(-)-free solution. Apical phlorizin, a blocker of Na+-glucose cotransport, eliminated one-half of the remaining I(SC). Cl- replacement with gluconate eliminated all I(SC) except the phlorizin-sensitive component. Unlike basal I(SC), 80 +/- 24% of stimulated I(SC) was inhibited by bumetanide. Thus basal and stimulated secretions are mediated by different mechanisms.

Amiloride↗
PubMed1997

Calcium-stimulated Cl- secretion in Calu-3 human airway cells requires CFTR.

Human airway serous cells secrete antibiotic-rich fluid, but, in cystic fibrosis (CF), Cl(-)-dependent fluid secretion is impaired by defects in CF transmembrane conductance regulator (CFTR) Cl- channels. Typically, CF disrupts adenosine 3',5'-cyclic monophosphate (cAMP)-mediated Cl- secretion but spares Ca(2+)-mediated secretion. However, in CF airway glands, Ca(2+)-mediated secretion is also greatly reduced. To determine the basis of Ca(2+)-mediated Cl- secretion in serous cells, we used thapsigargin to elevate intracellular Ca2+ concentration ([Ca2+]i) in Calu-3 cells, an airway cell line bearing some similarities to serous cells. Cells were cultured using conventional and air interface methods. Short-circuit current (Isc) and transepithelial conductance (Gte) were measured in confluent cell layers. Thapsigargin stimulated large, sustained changes (delta) in Isc and Gte, whereas forskolin stimulated variable and smaller increases. delta Isc was decreased by basolateral bumetanide, quinidine, barium, or diphenylamine-2-carboxylate (DPAC) but was unaffected by high apical concentrations of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 4,4'-dinitrostilbene-2,2'-disulfonic acid, and calixarene. Isc was measured after permeabilizing the basolateral membrane and establishing transmembrane ion gradients. Unstimulated apical membranes displayed high Cl- conductance (GCl) that was decreased by DPAC but not by DIDS. Apical GCl could be increased by elevating intracellular cAMP concentration but not [Ca2+]i. We conclude that CFTR channels are the exclusive GCl pathway in the apical membrane and display approximately 60% of maximum conductance at rest. Thus elevated [Ca2+]i increases K+ conductance to force Cl- through open CFTR channels. We hypothesize that loss of CFTR channels causes diminution of cholinergically mediated gland secretions in CF.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1996

Measurement of retinal blood flow with fluorescein leucocyte angiography using a scanning laser ophthalmoscope in rabbits.

AIMS: To measure blood flow in the rabbit retinal circulation with fluorescein leucocyte angiography using a scanning laser ophthalmoscope. METHODS: Blood was withdrawn from the ear vein of a rabbit (New Zealand White), mixed with fluorescent dye in a test tube and centrifuged. The yellow-brown layer containing fluorescein stained leucocytes was collected and injected into the ear vein of the same rabbit while performing fluorescein angiography with a scanning laser ophthalmoscope. The image of retinal angiography displaying circulating fluorescent leucocytes was recorded on video tape. From each frame of the video tape, the consecutive positions of fluorescein stained leucocytes were digitised using an image analysis system and the velocity of blood flow was calculated. RESULTS: Fluorescent leucocytes were clearly visualised in the retinal arteries, capillaries, and veins which allowed measurement of blood flow. The mean capillary velocity was 0.69 (SD 0.21) mm/s. The mean velocities of leucocytes measured in different sized vessels were as follows: 5.83 (2.42) mm/s in arteries over 50 microns, 3.33 (0.62) mm/s in those 35-50 microns, and 2.42 (1.08) mm/s in arteries under 35 microns, 3.08 (1.56) mm/s in veins over 50 microns, 2.79 (1.49) mm/s in those 35-50 microns, and 1.21 (0.50) mm/s in veins under 35 microns. Blood flow pulsation occurs in arteries, arterioles, veins, and venules but not capillaries. CONCLUSION: Fluorescein leucocyte angiography can be used for simultaneous measurement of the blood flow in retinal arteries, veins, and capillaries.

Animals↗
PubMed1995

Treatment of neuropathic urinary and faecal incontinence with synchronous bladder reconstruction and the antegrade continence enema procedure.

OBJECTIVES: To report our experience with synchronous bladder reconstruction and the antegrade continence enema (ACE) procedure in the management of neuropathic urinary and faecal incontinence. PATIENTS AND METHODS: Eight patients (four boys, four girls) with a median age of 9 years 10 months (range 4.5-17) were treated. Five had spina bifida, two high ano-rectal malformations and one had been successfully treated for a spinal neuroblastoma. The appendix was used for the ACE procedure in five patients and a tubularized caecal or colonic flap in the other three. Seven patients had an augmentation cystoplasty and one a cystectomy with a continent diversion. A bladder neck reconstruction or an urethral lengthening procedure was performed in five patients and the bladder outlet was closed in two. Six patients required some form of revision. Four patients underwent a simultaneous Mitrofanoff procedure. RESULTS: The median length of follow-up was 11.5 months (range 3-29). Five patients were completely clean and the remaining three experienced minor faecal soiling only. They were all delighted with the result. Six patients were dry day and night, one was wet at night only while the final patient was wet day and night. CONCLUSIONS: Synchronous surgical procedures to make patients with neuropathic incontinence both clean and dry is effective, but most patients require revision surgery. Patient motivation and selection and the availability of a nurse specialist is crucial in obtaining satisfactory results.

Adolescent↗