Adult females of the white-back planthopper, Sogatella furcifera, showed characteristic behavior of stylet sheath deposit on a parafilm membrane when fed on a 2% aqueous crude rice leaf and stem extract containing 15% sucrose. Subsequent bioassays revealed that the butanol-soluble fraction of the extract was highly active against the insects. When the butanol fraction was chromatographed on an ODS open column and eluted in sequence with a mixture of an increasing concentration of methanol in water, the 40 % methanol fraction was separated as the most active. A further bioassay of the HPLC components in the active fraction revealed that two major components (1 and 3) stimulated the high probing activity of the white-back planthopper only when they were combined. Of the active components, one component (3) was identified to be tricin 5-O-glucoside by spectroscopic analyses.

Animals↗

PubMed2000

Cytochrome b6/f complex as an indigenous photodynamic generator of singlet oxygen in thylakoid membranes.

Possible association of photodynamic sensitization by cytochrome b6/f complex (cyt b6/f) via singlet oxygen (1O2) mechanism with photoinhibition damage to photosystem II (PS II) was studied using such subthylakoid preparations as photosystem I (PS I) particles, PS II core complex and cyt b6/f from spinach leaves. Upon exposure to bright light, PS II core complex lost photosynthetic electron transport activity to a certain extent, whose-spectral dependence implied that pheophytin a is likely involved in photoinactivation of PS II core complex in itself. The presence of PS I particles exerted virtually no effect on PS II core photoinactivation. However, the inclusion of cyt b6/f in samples resulted in a marked exacerbation of the photoinactivation, particularly in UV-A and blue light. Such effect of cyt b6/f was suppressed by azide and enhanced by the medium deuteration. Photogeneration of 1O2 from cyt b6/f was confirmed by ESR and spectrophotometry, chemically trapping 1O2. Action spectra for both 1O2 photoproduction and PS II core photoinactivation by cyt b6/f bore a close resemblance to each other, seemingly carrying the absorption characteristics of the Rieske Fe-S protein. A complex deficient in the Rieske protein prepared from intact cyt b6/f showed virtually no generation of 1O2 in light, whereas an efficient photoformation of 1O2 was seen in the Rieske protein preparation. The results suggest that cyt b6/f, rather specifically the Rieske center, may play a prominent role in photoinhibition processes through type II photosensitization in thylakoids.

Cytochrome b Group↗

PubMed2000

Prolonged swimming exercise training induce hypophosphatemic osteopenia in stroke-prone spontaneously hypertensive rats (SHRSP).

Stroke-prone spontaneously hypertensive rats (SHRSP) induce spontaneous osteoporosis. To elucidate the specific characteristics of bone metabolism, the SHRSP was compared with age matched Wistar-Kyoto (WKY) rats. We investigated the effects of prolonged swimming exercise training on bone mineral density (BMD) and metabolism in the SHRSP. Seven-week-old male SHRSP and WKY were divided into three groups; the sedentary control WKY group (n = 6, WKY), the sedentary control SHRSP group (n = 6, SP) and the swimming exercise training SHRSP group (n = 6, SWIM) (in pool with 60 min./day, 5 days/week for 12 weeks). The femoral BMD, bone mineral content (BMC), strength, Ca and P contents (%) of SHRSP were approximately 17, 27, 25, 20 and 9%, respectively, lower than that of WKY (p < 0.001). Serum alkaline phosphatase (AlP) had not changed between both of SP and WKY, but tartrate-resistant acid phosphatase (TrAcP) of SP approximately 3-fold higher than that of WKY (p < 0.05). Both serum calcium (Ca) and intact parathyroid hormone (i-PTH) were similar between SP and WKY. However, serum phosphate (P) of SP was approximately 18% lower than that of WKY (N.S.). These results suggested that SHRSP induces osteopenia by the bone turnover of the promoted osteoclast activity with disturbed phosphate homeostasis. On the other hand, the femoral BMD and strength were approximately 7% and 20%, respectively, decreased in the SWIM (p < 0.001), and femoral bone Ca and P contents (%) were also approximately 11% and 14%, respectively, lower than that of SP (p < 0.001). There were no significant difference between SWIM and SP on serum Ca, but serum P of SWIM was significantly lower than that of SP (p < 0.05). These results suggested that the prolonged swimming exercise training in the SHRSP induces more cruelly hypophosphatemia, and leading to osteopenia eventually. We conclude that SHRSP induces osteopenia with disturbance of phosphate homeostasis, and the prolonged swimming exercise in the SHRSP might deteriorate hypophosphatemia and osteopenia.

Animals↗

PubMed2000

Consensus statement: aerosols and delivery devices. American Association for Respiratory Care.

Explore the source record for details and available documents.

Aerosols↗

PubMed2000

Methods of calculating lung delivery and deposition of aerosol particles.

Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monodisperse aerosols. However, for polydisperse and/or unstable hygroscopic aerosols, measurement methods are limited and often unreliable. Regional deposition is assessed primarily by gamma scintigraphy. The scintigraphic method is useful for a general description of deposition patterns, but may not be adequate for quantitative regional dose estimation. New emerging three-dimensional lung imaging methods such as SPECT and PET, and innovative bolus aerosol delivery methods, have great potential for measuring detailed regional deposition. An accurate assessment of regional lung dose is difficult to achieve by the current methods. A multi-prong approach may be needed, with various methods and techniques, both in theory and experiment, to measure site-specific deposition dose.

Aerosols↗

PubMed2000

Vasoconstrictive eicosanoid responses to extracorporeal circulation with or without an oxygenator in fetal lambs.

INTRODUCTION: This study measured levels of vasoconstrictive eicosanoids during ovine fetal cardiac bypass and compared the measurements between two groups: (1) a group in which the placenta functioned as the only source of oxygen supply during the bypass (the placenta group), and (2) a group in which an artificial oxygenator, instead of the placenta, was included in the bypass circuit (the oxygenator group). MATERIALS AND METHODS: A total of 16 fetal lambs were randomly assigned into either the oxygenator group or the placenta group. Following anesthesia, the fetal cardiac bypass procedure was performed. The placenta group used a centrifugal pump as the pumping device without an oxygenator during the bypass. The bypass circuit in the oxygenator group consisted of a roller pump and a membrane oxygenator. The fetal cardiac bypass procedure was performed for 30 minutes at normothermia in both groups. For the measurements of thromboxane B2(TXB2) and prostaglandin E2 (PGE2), blood samples were taken before the bypass, at 5 minutes, 15 minutes, and 30 minutes after the start of cardiac bypass, and at 15 minutes after weaning from the bypass. TXB2 and PGE2 levels were determined by radioimmunoassay with PGE2(125I) and TXB2(125I) assay systems. Hemodynamic observations and arterial blood gas analyses were done every 10 minutes. RESULTS: The mean arterial pressure and heart rate ranged from 69.8 to 82.6 mmHg and 169 to 182/min during the bypass in the oxygenator group, and from 14.4 to 44.7 mmHg and 64.3 to 75/min in the placenta group. Arterial blood gas analysis showed severe hypercapnia and hypoxemia with acidosis during and after the bypass in the placenta group. Bypass flow rates were maintained at 140.3-164.0 ml/kg/min in the oxygenator group, while flow rates were suboptimal (74.3-97.0 ml/kg/min) in the placenta group. There were no statistically significant differences in PGE2 concentrations before, during, or after bypass, although the placenta group displayed a tendency to higher measurements during bypass, compared to the oxygenator group. The placenta group also showed higher TXB2 measurements than the oxygenator group during the bypass (p = 0.0457). CONCLUSIONS: We have demonstrated increase measurements of PGE2 and TXB2 in the placenta group when compared with the oxygenator group in an ovine fetal cardiac bypass model, although the PGE2 difference failed to reach statistical significance.

Animals↗

PubMed2000

Can peer-comparison feedback improve patient functional status?

OBJECTIVE: To determine whether providing physicians with peer-comparison feedback can improve patient functional status. STUDY DESIGN: Randomized, controlled, comparative study. METHODS: Forty-eight primary care physicians at Kaiser Permanente Woodland Hills, a group-model health maintenance organization in southern California, were randomly assigned to an intervention group or a control group. All physicians were informed that their elderly patients (randomly selected patients aged 65 to 75) would be monitored. Physicians in the intervention group received aggregated peer-comparison feedback data (physician "report cards") on the functional status of their elderly patients. Physicians in the control group received only general information that their patients' functional status would be monitored. The effect of the intervention on patients' functional status was determined by comparing responses to surveys completed by the patients at baseline and after the intervention. RESULTS: Patients in both the control and intervention groups had a statistically significant decrease in functional status, including decreases in their ability to complete daily activities and increases in pain. In addition, patients in the control group reported a significant decrease in social activities, physical fitness, and feelings. In the intervention group, patients also experienced a significant decrease in social support. CONCLUSIONS: Educational interventions, including peer-comparison feedback, did not result in improvements in patient functional status. Research is desperately needed to identify interventions that can lead to improved health for elderly patients.

Activities of Daily Living↗

PubMed2000

Effect of Korean red ginseng on blood pressure and nitric oxide production.

AIM: To investigate the effect of crude saponin and nonsaponin fraction of Korean red ginseng (KRG) on the blood pressure and nitric oxide (NO) production in the conscious rats and cultured endothelial cell line, ECV 304 cells. METHODS: Systolic blood pressure and heart rate were monitored in the conscious rats. Nitric oxide levels and the expression of nitric oxide synthase were measured by a spectrophotometric assay using Griess reagents and Western blotting, respectively. Nitric-oxide synthase activity was measured based on the conversion rate of [3H]arginine to [3H]citrulline. RESULTS: Systolic blood pressure was decreased by crude saponin (100 mg/kg, i.v.) of KRG in the conscious control and one-kidney, one-clip Goldblatt hypertensive (1K, 1C-GBH) rats. The hypotensive effect induced by crude saponin of KRG reached maximum at 2-4 min and slowly recovered after 20 min to the initial level in both groups. Crude saponin of KRG induced tachycardia in the conscious rats but induced bradycardia in the anesthetized rats. In contrast to crude saponin of KRG, hypotensive effect induced by saponin-free fraction was minimal. Nitric oxide concentrations were increased by the treatment of crude saponin in conscious rats as well as in the cultured ECV 304 cells. The protein expression level of endothelial constitutive nitric-oxide synthase (eNOS) in the aorta of rats was not increased by crude saponin (100 mg/kg, i.p. for 3 d). However, nitric-oxide synthase activity was increased by crude saponin of KRG in the aortic homogenate of rats. CONCLUSION: The hypotensive effect of red ginseng is mainly due to saponin fraction of KRG in the conscious rats, and this effect may be due to an increase in the nitric-oxide production by KRG.

Animals↗

PubMed2000

Immobilization on the day 14th does not disrupts the basic diurnal rhythm of bone resorption.

Weight bearing and physical activity are important mechanical stimuli to bone growth and metabolism, and microgravity, such a space flight and/or bed rest, induces bone resorption and bone loss. An increased excretion of urinary Ca, an increased bone resorption and a decreased bone mineral density (BMD) have been observed in bed rest experiment of healthy subjects. Bone resorption markers show the specific circadian rhythms in human. Cross-linked carboxyl-terminal telopeptide of type I collagen (ICTP) and the urinary excretion of deoxypyridinoline (Dpy) are the highest in the early morning and the lowest late at night. Bed rest immobilization might influence these rhythms, due to no mechanical loading with loss of daily life activity. Bone resorption markers in healthy subjects had been compared between before and during bed rest to determine disruption of diurnal rhythms of bone resorption.

Acid Phosphatase↗

PubMed2000

Evaluation of psychological effects due to bed rest.

The psychological condition of astronauts is an important factor for ensuring mission success in limited space. Head-down tilting bed rest is a well-accepted method by which to simulate an acute stage of human adaptation to the weightless state in space flight. In our previous studies, the enhancement of depressive and neurotic levels occurred during a 20-day horizontal bed rest. In this study, we attempted to examine the depressive and neurotic levels, the mood status, and behavioral tendency of the subjects and to analyze the changes of 24-hour urinary excretion of 17-hydroxycorticosteroid-glucronides (17-OHCS) for an indicator of changes in the endocrine system due to physical and psychological stress during a 20-day 6-degrees head-down tilting bed rest (BR).

17-Hydroxycorticosteroids↗

PubMed1999

Dual mechanisms for glucose 6-phosphate inhibition of human brain hexokinase.

Brain hexokinase (HKI) is inhibited potently by its product glucose 6-phosphate (G6P); however, the mechanism of inhibition is unsettled. Two hypotheses have been proposed to account for product inhibition of HKI. In one, G6P binds to the active site (the C-terminal half of HKI) and competes directly with ATP, whereas in the alternative suggestion the inhibitor binds to an allosteric site (the N-terminal half of HKI), which indirectly displaces ATP from the active site. Single mutations within G6P binding pockets, as defined by crystal structures, at either the N- or C-terminal half of HKI have no significant effect on G6P inhibition. On the other hand, the corresponding mutations eliminate product inhibition in a truncated form of HKI, consisting only of the C-terminal half of the enzyme. Only through combined mutations at the active and allosteric sites, using residues for which single mutations had little effect, was product inhibition eliminated in HKI. Evidently, potent inhibition of HKI by G6P can occur from both active and allosteric binding sites. Furthermore, kinetic data reported here, in conjunction with published equilibrium binding data, are consistent with inhibitory sites of comparable affinity linked by a mechanism of negative cooperativity.

Allosteric Site↗

PubMed1999

Alterations of Fas (APO-1/CD95) gene in transitional cell carcinomas of urinary bladder.

Fas (Apo-1/CD95) is a cell-surface receptor involved in cell death signaling. The key role of the Fas system in negative growth regulation has been studied mostly within the immune system, and somatic mutations of Fas in cancer patients have been described solely in lymphoid-lineage malignancies. We analyzed somatic mutations and loss of heterozygosity of Fas gene in 43 transitional cell carcinomas of urinary bladder. Overall, 12 tumors (28%) were found to have Fas mutations, including 11 missense mutations and 1 frameshift mutation. Ten of the 12 mutations were located in the death domain known to be involved in the transduction of an apoptotic signal, and 8 of these 10 mutations showed an identical G to A transition at bp 993, indicating a potential hotspot in bladder cancers. Three of eight (38%) informative tumors carrying Fas mutations showed LOH at polymorphic sites in the promoter region. This is the first report on the Fas gene mutations in nonlymphoid malignancies, and our data suggest that alterations of the Fas gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some bladder cancers.

Amino Acid Substitution↗