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PubMed2003

Control of water uptake by rice ( Oryza sativa L.): role of the outer part of the root.

A new pressure-perfusion technique was used to measure hydraulic and osmotic properties of the outer part of roots (OPR) of 30-day-old rice plants (lowland cultivar: IR64, and upland cultivar: Azucena). The OPR comprised rhizodermis, exodermis, sclerenchyma and one cortical cell layer. The technique involved perfusion of aerenchyma of segments from two different root zones (20-50 mm and 50-100 mm from the tip) at precise rates using aerated nutrient solution. The hydraulic conductivity of the OPR (Lp(OPR)=1.2x10(-6) m s(-1) MPa(-1)) was larger by a factor of 30 than the overall hydraulic conductivity (Lp(r)=4x10(-8) m s(-1) MPa(-1)) as measured by pressure chamber and root pressure probe. Low reflection coefficients were obtained for mannitol and NaCl for the OPR (sigma(sOPR)=0.14 and 0.09, respectively). The diffusional water permeability ( P(dOPR)) estimated from isobaric flow of heavy water was smaller by three orders of magnitude than the hydraulic conductivity (Lp(OPR)/ P(fOPR)). Although detailed root anatomy showed well-defined Casparian bands and suberin lamellae in the exodermis, the findings strongly indicate a predominantly apoplastic water flow in the OPR. The Lp(OPR) of heat-killed root segments increased by a factor of only 2, which is in line with the conclusion of a dominating apoplastic water flow. The hydraulic resistance of the OPR was not limiting the passage of water across the root cylinder. Estimations of the hydraulic properties of aerenchyma suggested that the endodermis was rate-limiting the water flow, although the aerenchyma may contribute to the overall resistance. The resistance of the aerenchyma was relatively low, because mono-layered cortical septa crossing the aerenchyma ('spokes') short-circuited the air space between the stele and the OPR. Spokes form hydraulic bridges that act like wicks. Low diffusional water permeabilities of the OPR suggest that radial oxygen losses from aerenchyma to medium are also low. It is concluded that in rice roots, water uptake and oxygen retention are optimized in such a way that hydraulic water flow can be kept high in the presence of a low efflux of oxygen which is diffusional in nature.

Biological Transport↗

PubMed2004

[Comparison of costs-of-illness in a year before and after inpatient and outpatient rehabilitation in persons with spinal disorders].

The present economic analyses of orthopaedic inpatient and outpatient rehabilitation (IPR resp. OPR) focus but on the evaluation of the expenses from the cost carrier's perspective. Lower intervention costs were related to OPR, whereas comparable social and clinical outcome was achieved. Comprehensive assessment of the economic consequences (resource utilization and lost productivity) of low back pain have not been performed up to now. Therefore, as part of a prospective follow-up study (1) a comparison of overall cost-of-illness and cost components 12 months prior and after IPR and OPR, respectively, was carried out in patients with low back pain and (2) the relative changes of these cost components were compared in a full-cost-analysis from a societal perspective. A total of 150 matched pairs (SR and AR) were followed prospectively over 12 months. Disease related costs in the year prior to the intervention were evaluated retrospectively. Prior to IPR and OPR overall costs amounted to 7010 and 7710 Euro, respectively, per person and year in patients with low back pain. As the main cost component of overall costs, sick leave (SL) periods account for 74% (IPR) and 76% (OPR), respectively. Inpatient costs represent the main component of direct costs. In the year after the intervention the costs due to sick leave periods still represent the major cost component (46 and 52%, resp.) of overall costs (3370 and 3600 Euro, resp.). Disease related cessation of work including work disability accounts for about 10% of productivity costs after IPR and OPR. Indirect costs still make up for the major part of overall costs (58 and 62%, resp.). No differences of cost components and their relative changes can be seen between patients participating in IPR and OPR, respectively, within both time frames. The comparison of overall costs in the 12 months before and after IPR and OPR reveals a cost reduction of 52% (IPR) and 53% (OPR), resp. This decrease of costs is mainly related to the reduction of SL periods, though costs due to inpatient treatment decrease as well. Summarizing, the present full-cost-analysis from a societal perspective shows no differences of cost components and cost changes between orthopaedic IPR and OPR in the 12 months prior to and after the intervention. Comprehensive cost-analyses reveal no obstacles for further implementation of OPR in the treatment of low back pain. Future development and diversification of rehabilitation measures should aim at evaluating real resource consumption during the intervention in detail as a basis for further allocational decision making.

Ambulatory Care↗

PubMed2003

Characterization of specific opioid binding sites in neural membranes from the myenteric plexus of porcine small intestine.

Delta- and kappa-opioid receptors (OPRs), but not micro-OPRs, are expressed in the myenteric plexus of the porcine distal small intestine. In a subpopulation of myenteric neurons, delta- and kappa-OPRs seem to be colocalized and may functionally interact. In this study, radioligand binding was used to characterize myenteric OPR populations in detail. The nonselective OPR antagonist [3H]diprenorphine bound to a single, high-affinity site in myenteric neural membrane homogenates. Naloxone displaced 65 and 59% of [3H]diprenorphine binding from this site in Na(+)-free Tris and Krebs-HEPES buffers, respectively. Naltrexone-derived delta- and kappa-OPR antagonists, including naltriben, 7-benzylidenenaltrexone, nor-binaltorphimine, and 5'-guanidinonaltrindole, displaced [3H]diprenorphine from two distinct binding sites to levels similar to that of naloxone. The selective delta-OPR ligands Tyr-1,2,3,4-tetrahydroisoquinoline-Phe-Phe-OH (TIPP), [D-Pen2,D-Pen5]enkephalin (DPDPE), [D-Ala2, Glu4]deltorphin II, and (+)-4-[(alphaR)-alpha((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl-3-methoxybenzyl)-N,N-diethylbenzamide (SNC-80) and the kappa-OPR agonist (D-(5alpha,7alpha,8beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1-oxoaspiro-(4,5)dec-8-yl) benzeneacetamide (U-69,593) displaced [3H]diprenorphine from three independent binding sites; these included high-affinity delta- and kappa-OPR sites, and a residual binding site. Residual [3H]diprenorphine binding was displaced by the selective kappa-OPR antagonist nor-binaltorphimine after saturation of delta and kappa sites, respectively, with DPDPE and U-69,593. The residual binding site displayed low affinity for delta- and kappa-OPR agonists and TIPP, as well as moderate affinity for naltrexone-derived ligands, properties reminiscent of delta-/kappa-OPR heterodimers.

Animals↗

PubMed1996

A single residue, Lys108, of the delta-opioid receptor prevents the mu-opioid-selective ligand [D-Ala2,N-MePhe4,Gly-ol5]enkephalin from binding to the delta-opioid receptor.

Previously, we found that replacement of the region around the first extracellular loop of the delta-opioid receptor (OPR) with the corresponding region of the mu-OPR gives the high affinity for [D-Ala2,N-MePhe4,Gly-ol5]enkephalin (DAMGO), a mu-opioid-selective ligand, to the resultant chimeric receptor, DMDD, suggesting that the difference in the amino acid sequence within this region between the mu- and delta-OPRs is critical for the discrimination between these receptors by DAMGO. In the current study, we carried out systematic replacements of seven non-conserved residues in this region of the delta-OPR with the corresponding amino acid found in the mu-OPR. Among the seven mutant receptors, only one mutant receptor, delta K108N, showed high affinity (Ki = 18.68 +/- 5.27 nM) for DAMGO, which was comparable to that of the DMDD receptor (Ki = 23.77 +/- 4.27 nM) and 75-fold higher than that of the wild-type delta-OPR (Ki = 1405 +/- 161 nM). Lys108 in the delta-OPR was systematically replaced with 19 kinds of amino acids other than lysine. Among the resultant mutant receptors, 14 mutants bound DAMGO with Ki values comparable to those of the DMDD receptor, ranging from 4.20 to 43.38 nM. These findings suggest that Lys108 of the delta-OPR prevents DAMGO from binding to the delta-OPR rather than that the asparagine residue at the corresponding position in the mu-OPR is necessary for DAMGO binding. In addition, the replacement of Lys108 of the delta-OPR with asparagine dramatically increased the affinity for other peptidic mu receptor-selective ligands, such as dermorphin and D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2.

Adenylyl Cyclases↗

PubMed1999

Protection of mice against P. aeruginosa infections by large-scale affinity-purified human IgG specific to P. aeruginosa outer membrane proteins.

In order to develop an effective means to treat Pseudomonas aeruginosa infections, we designed a large-scale process for purification of human IgG specific to P. aeruginosa outer membrane proteins (Oprs) from normal human sera. The process we developed includes affinity column chromatography using P. aeruginosa Oprs as ligands, protein A column chromatography and ultrafiltration, which enriched P. aeruginosa Oprs-specific IgG antibody by 500-fold. The purified anti-Oprs IgG was specific to the Oprs as confirmed by an ELISA competition assay and retained opsonophagocytic-killing capacity. In vivo protective efficacy of anti-Oprs IgG was evaluated by passive protection assays in mice where the 50% protective dose of anti-Oprs IgG against P. aeruginosa infections was 41 microg/kg, which was 20 times lower than that of normal serum IgG. When administered to mice 3 h after bacterial challenge, only anti-Oprs IgG afforded protection. These data demonstrate the feasibility of use of the purification process in producing functionally active target-specific human antibodies for clinical use and provide a rationale for use of anti-Oprs IgG as a valuable adjunct to treat P. aeruginosa infections.

Animals↗

PubMed2000

[Molecular neuropharmacology of nociceptive transmission and opioid receptors].

This review summarizes our studies using pharmacological, neurochemical and molecular biological methods on the nociception in the CNS and opioid receptors (OPRs). We designed an in vitro fluorometric on-line monitoring system including an immobilized glutamate dehydrogenase column, and for the first time actually demonstrated that capsaicin induced the release of glutamate from rat dorsal horn slices containing the terminal area of primary afferents, in concentration-dependent, extracellular Ca(2+)-dependent and tetrodotoxin-resistant manners. Further, such a release was shown to be inhibited through mu- and delta-opioid receptors and alpha 2-adrenoceptors. On the other hand, we found that intracerebroventricular injections of interleukin (IL)-1 beta in rats produced biphasic effects on the mechanical nociception in rats (hyperalgesia in lower concentrations but analgesia in higher ones) and that similar injections of cytokine-induced neutrophil chemoattractant-1 (CINC-1) facilitated mechanical nociception in rats. The above described facts suggest that glutamate and some sorts of cytokines (IL-1 beta and CINC-1) contribute to nociception at least from the primary afferents to the spinal dorsal horn neurons and in higher brain, respectively. We have cloned rat kappa- and mu-opioid receptors. Using cloned cDNA for OPRs, we demonstrated (1) the distribution of mRNAs for OPRs in the rat central nervous system, (2) coexistence of each type of mRNA for mu-, delta- and kappa-OPRs and pre-protachykinin A mRNA in the dorsal root ganglion neurons, (3) an increased expression of mu- and kappa-OPR mRNAs in the I-II layers of rat lumbar dorsal horn with an adjuvant arthritis in the hind limb, (4) the inhibitions of N- and Q-types of Ca2+ channels by mu- and kappa-OPR agonists and (5) cross-desensitization of the inhibition through a common intracellular phosphorylation-independent mechanism, (6) pharmacological characterization of "antagonist analgesics" as partial agonists at every type of OPRs, and (7) the key-structure(s) of OPRs for discriminative binding of DAMGO to mu-OPR.

Analgesics, Opioid↗

PubMed2001

Reduction of oscillatory pressure along the endotracheal tube is indicative for maximal respiratory compliance during high-frequency oscillatory ventilation: a mathematical model study.

We hypothesized that during high-frequency oscillatory ventilation (HFOV), a reduction of peak-to-peak oscillatory pressure along the endotracheal tube is maximal when respiratory system compliance is maximal. We made a mathematical model of the endotracheal tube and the respiratory system of a neonate suffering from idiopathic respiratory distress syndrome (IRDS). The model consisted of linear viscous and inertive elements, a non-linear endotracheal tube resistance, and a non-linear compliance allowing for alveolar recruitment and overdistention. Respiratory compliance was maximal at the transition between maximal recruitment and minimal overdistention. A new variable, the oscillatory pressure ratio (OPR), was defined as the ratio between peak-to-peak oscillatory pressures at the distal end and the proximal opening of the endotracheal tube, respectively. The respiratory variables of four patients were fed into the model, and the relationship between respiratory system compliance and OPR was determined. OPR decreased as compliance increased, except for very low compliances below where 0.08 mL. cm H2O(-1), and OPR increased with increasing compliance. The relationship between mean airway pressure P(aw) and OPR revealed that the minimal OPR (range, 0.37-0.78) and maximal respiratory compliance coincided at the same P(aw). However, the relationship did depend on oscillation frequency, applied oscillatory pressure, and endotracheal tube resistance, parameters that may change during clinical application of HFOV. When 81 permutations of nominal and extreme respiratory variables were used in the model, the minimum OPR (0.60 +/- 0.23) and maximum compliance coincided in all cases. These model experiments support our hypothesis. The results indicate that the OPR may be a useful index to optimize lung expansion, where lung recruitment is maximal and overdistention minimal. In vivo tests will be needed to reveal the feasibility and reliability of such an index for biomedical and clinical application.

Airway Resistance↗

PubMed2006

Performance following prolonged sub-maximal cycling at optimal versus freely chosen pedal rate.

It was tested whether cyclists perform better during all-out cycling following prolonged cycling at the pedal rate resulting in minimum oxygen uptake (VO(2)), i.e. the energetically optimal pedal rate (OPR) rather than at the freely chosen pedal rate (FCPR). Nine trained cyclists cycled at 180 W to determine individual OPR and FCPR. Baseline performance was determined by measuring mean power output (W(5min)) and peak VO(2) during 5-min all-out cycling at FCPR. Subsequently, on two separate days, the cyclists cycled 2.5 h at 180 W at OPR and FCPR, with each bout followed by a 5-min all-out trial. FCPR was higher (P < 0.05) than OPR at 180 W (95 +/- 7 and 73 +/- 11 rpm, respectively). During the prolonged cycling, VO(2), heart rate (HR), and rate of perceived exertion (RPE) were 7-9% higher (P < 0.05) at FCPR than at OPR and increased (P < 0.05) 2-21% over time. During all-out cycling following prolonged cycling at OPR and FCPR, W(5min) was 8 and 10% lower (P < 0.05) than at baseline, respectively. Peak VO(2) was lower (P < 0.05) than at baseline only after FCPR. The all-out trial power output was reduced following 2.5 h of cycling at 180 W at both OPR and FCPR. However, this aspect of performance was similar between the two pedal rates, despite a higher physiological load (i.e. VO(2), HR, and RPE) at FCPR during prolonged cycling. Still, a reduced peak VO(2) only occurred after cycling at FCPR. Therefore, during prolonged sub-maximal cycling, OPR is at least as advantageous as FCPR for performance optimization in subsequent all-out cycling.

Adult↗

PubMed2005

Prediction of costs-of-illness in patients with low back pain undergoing orthopedic outpatient rehabilitation.

The objectives of this study were (1) to assess societal costs-of-illness and their changes in the year prior to and after outpatient rehabilitation (OPR) in initially gainfully employed persons with low back pain and (2) to identify predictors (cost drivers) for high overall costs in the year after the intervention. The health economical analysis is part of a prospective clinical trial investigating patients participating in orthopedic OPR. In all gainfully employed patients (n=244) resource consumption and productivity losses were assessed prior to OPR and 12 months afterwards. Overall annual medical costs per person were estimated. Parameters associated with high overall costs in the 12 months after OPR were predicted by multivariate logistic regression analysis. All sociodemographic, motivational, clinical, psychological, therapeutic and vocational variables were included as possible predictors. Costs due to sick leave periods represent the major component (83%/58%) of overall costs in both periods. The comparison of costs 12 months before and after OPR reveals a significant reduction from 8050 to 3200 per person, primarily caused by decreasing sick leave costs and the reduction of costs related to inpatient treatment. The prediction analysis reveals that patients with limited functional abilities, with problems due to strenuous labour, with low expectations in terms of possible improvement after OPR, with a high pain score or with limited satisfaction with working colleagues have a significantly higher risk for costs exceeding 2200 after OPR. The identified cost drivers can be used to develop multimodal therapeutic measures, which should be employed during the OPR intervention in order to prevent future costs.

Adult↗

PubMed1999

Human anti-Pseudomonas aeruginosa outer membrane proteins IgG cross-protective against infection with heterologous immunotype strains of P. aeruginosa.

In order to develop an effective means to treat and prevent Pseudomonas aeruginosa infections, we have purified P. aeruginosa outer membrane protein (Oprs)-specific human IgG antibody using a large-scale affinity column. In this study, we investigated the cross-protective activity of the purified anti-Oprs IgG against various immunotype strains of P. aeruginosa. The anti-Oprs IgG reacted with Oprs isolated from seven Fisher-Devlin immunotype strains of P. aeruginosa and was able to promote opsonophagocytic killing of all seven immunotype strains by human phagocytic cells. Administration of 500 microg anti-Oprs IgG to mice raised the LD50 of the P. aeruginosa strains by 8-250-fold, indicating the protective capacity against heterologous P. aeruginosa strains as well as homologous strains. In contrast, despite high titers against P. (aeruginosa Oprs, total serum IgG isolated from burn patient sera was no better than normal serum IgG in protecting mice from infection with P. aeruginosa. These data demonstrate that the affinity-purified human anti-Oprs IgG could afford protection against heterologous immunotype P. aeruginosa strains and provide a rationale to use anti-Oprs IgG as an adjunct for treatment of P. aeruginosa infections in humans.

Animals↗

PubMed1995

DAMGO, a mu-opioid receptor selective agonist, distinguishes between mu- and delta-opioid receptors around their first extracellular loops.

The structural basis of mu-opioid receptor (OPR) for the specificity in its ligand binding was investigated using chimeric mu/delta-OPRs. Replacement of the region around the first extracellular loop of delta-OPR with the corresponding region of mu-OPR gave the resultant chimeric receptor the similar affinity to DAMGO compared with the native mu-OPR. The reciprocal replacement deprived the high affinity to DAMGO from mu-OPR. These results indicate that the difference(s) in the structure around the first extracellular loop is critical for DAMGO to distinguish between mu- and delta-OPRs. Furthermore, displacement studies revealed that this region is partly involved in the discrimination between mu- and delta-OPRs by other peptidic mu-selective ligands, such as dermorphin, morphiceptin and CTOP, but not by non-peptidic ligands, such as morphine and naloxone.

Amino Acid Sequence↗

PubMed1988

Orosomucoid:prealbumin ratio--a marker of the host-tumor relationship in head and neck cancer.

The OPR was studied in 203 patients with squamous cell carcinoma of the head and neck at the time of diagnosis, before any specific treatment. The mean initial OPR value was significantly higher in cancer patients than in 63 healthy controls: 5.29 +/- 3.09 vs. 2.63 +/- 1.07; P less than 0.001. There was no significant difference by anatomic site, but the OPR was significantly lower in stage I-II disease than in stage III-IV: 5.10 +/- 3.85 vs. 3.23 +/- 1.99, P less than 0.001. An initial OPR under or over 6 seems to be an important prognostic factor: at 2 years, 51% of patients with an OPR less than 6 were alive vs. only 24.5% of those with an OPR greater than 6, P less than 0.001. The difference was also noted in patients with stage III-IV disease (mean survival: 16 months vs. 7 months, P less than 0.001) and in 89 of the patients who received chemotherapy (mean survival 16 months vs. 6 months, P less than 0.001) whatever the response to chemotherapy. The OPR index, which explores nutritional and acute phase reactant proteins, seems to reflect the host-tumor relationship. Its initial value is strongly related to prognosis at 2 years.

Adult↗

PubMed2004

Cross-talk of opioid peptide receptor and beta-adrenergic receptor signalling in the heart.

Opioid peptide receptor (OPR) and beta-adrenergic receptor (beta-AR) are well-established members of G-protein-coupled receptor (GPCR) superfamily and are involved in regulating cardiac contractility, energy metabolism, myocyte survival or death. OPRs are typical Gi/Go-coupled receptors and activated by opioid peptides derived from the endorphin, dynorphin and enkephalin families, whereas beta-AR stimulated by catecholamines is the model system for Gs-coupled receptors. While it is widely accepted that beta-AR stimulation serves as the most powerful means to increase cardiac output in response to stress or exercise, we have only begun to appreciate functional roles of OPR stimulation in regulating cardiovascular performance. Cardiovascular regulatory effects of endogenous opioids were initially considered to originate from the central nervous system and involved the pre-synaptic co-release of norepinephrine with enkephalin from sympathetic neuronal terminals in the heart. However, opioid peptides of myocardial origin have been shown to play important roles in local regulation of the heart. Notably, OPR stimulation not only inhibits cardiac excitation-contraction coupling, but also protects the heart against hypoxic and ischemic injury via activation of Gi-mediated signalling pathways. Further, OPRs functionally and physically cross-talk with beta-ARs via multiple hierarchical mechanisms, including heterodimerization of these receptors, counterbalance of functional opposing G protein signalling, and interface at downstream signalling events. As a result, the beta-AR-mediated positive inotropic effect and increase in cAMP are markedly attenuated by OPR activation in isolated cardiomyocytes as well as sympathectomized intact rat hearts. This brief review will focus on the interaction between beta-AR and OPR and its potential physiological and pathophysiological relevance in the heart.

Aging↗

PubMedDate not supplied

[Prognosis of labour force participation after multidisciplinary outpatient and inpatient rehabilitation for chronic back pain].

UNLABELLED: In a one-year prospective study of patients participating in a multidisciplinary outpatient or inpatient rehabilitation program (OPR/IPR) for chronic back pain the following issues were investigated: (i) the frequency of low labour force participation (LFP), i. e., work loss due to the disease or total duration of sick leave (SL) of 6 weeks or more; (ii) prognostic indicators at the beginning of the rehabilitation program (T1) for low LFP after one year (T2); (iii) the significance of the type of rehabilitation IPR vs. OPR in relation to the identified prognostic indicators for LFP. A total of 413 patients participating in OPR (n = 299) or IPR (n = 114) for chronic back pain returned a postal questionnaire after one year. Low LFP was found in 30 % of all patients without significant differences between OPR (32 %) and IPR (25 %). Compared to the year before T1 the proportion of patients without SL between T1 and T2 increased from 12 % to 48 % after OPR, from 15 % to 47 % after IPR, respectively. In multivariate logistic regression analyses adjusted for type of rehabilitation the following prognostic indicators of T1 for low LFP were identified (p </= 0,05): SL of 6 weeks or more in the year before T1 with an odds ratio (OR) of 11.1; intended termination of employment (OR = 3.2), household income of less than 3300 DM per month (OR = 2.2); reduced social functioning (SF-36) (OR = 2.0). Regarding LFP no significance of the type of rehabilitation (IPR vs. OPR) was found in relation to the identified prognostic indicators or after adjustment for differences (i) in the characteristics of the patients at T1, and (ii) in the duration and number of single measures of the rehabilitation program. CONCLUSIONS: One year after IPR or OPR the rate of return to work is similar (about seven out of ten patients). The identified prognostic indicators may stimulate further research of the improvement of the rehabilitation processes. No evidence was found against the expansion of OPR.

Adult↗

PubMed2004

Water permeability and reflection coefficient of the outer part of young rice roots are differently affected by closure of water channels (aquaporins) or blockage of apoplastic pores.

The relative contribution of the apoplastic and cell-to-cell paths to the overall hydraulic conductivity of the outer part of rice roots (LpOPR) was estimated using a pressure perfusion technique for 30-d-old rice plants (lowland cultivar, IR64, and upland cultivar, Azucena). The technique was based on the perfusion of aerenchyma of root segments from two different zones (20-50 mm and 50-100 mm from the root apex) with aerated nutrient solution using precise pump rates. The outer part of roots (OPR) comprised an outermost rhizodermis, an exodermis, sclerenchyma fibre cells, and the innermost unmodified cortical cell layer. No root anatomical differences were observed for the two cultivars used. Development of apoplastic barriers such as Casparian bands and suberin lamellae in the exodermis were highly variable. On average, matured apoplastic barriers were observed at around 50-70 mm from the root apex. Lignification of the exodermis was completed earlier than that of sclerenchyma cells. Radial water flow across the OPR was impeded either by partially blocking off the porous apoplast with China ink particles (diameter 50 nm) or by closing water channels (aquaporins) in cell membranes with 50 micro M HgCl2. The reduction of LpOPR was relatively larger in the presence of an apoplastic blockage with ink ( approximately 30%) than in the presence of the water channel blocker ( approximately 10%) suggesting a relatively larger apoplastic water flow. The reflection coefficient of the OPR (sigmasOPR) for mannitol significantly increased during both treatments. It was larger when pores of the apoplast were closed, but absolute values were low (overall range of sigmasOPR=0.1-0.4), which also suggested a large contribution of the non-selective, apoplastic path to overall water flow. The strongest evidence in favour of a predominantly apoplastic water transport came from the comparison between diffusional (PdOPR, measured with heavy water, HDO) and osmotic water permeability (PfOPR) or hydraulic conductivity (LpOPR). PfOPR was larger by a factor of 600-1400 compared with P(dOPR). The development of OPR along roots resulted in a decrease of PdOPR by a factor of three (segments taken at 20-50 and 50-100 mm from root apex, respectively). Heat-killing of living cells resulted in an increase of PdOPR for both immature (20-50 mm) and mature (50-100 mm) root segments by a factor of two. Even though both pathways (apoplast and cell-to-cell) contributed to the overall water flow, the findings indicate predominantly apoplastic water flow across the OPR, even in the presence of apoplastic barriers. Low diffusional water permeabilities may suggest a low rate of oxygen diffusion across the OPR from aerenchyma to the outer anaerobic soil medium (low PO2OPR). To date, there are no data on PO2OPR. Provisional data of radial oxygen losses (ROL) across the OPR suggest that, unlike water, rice roots efficiently retain oxygen within the aerenchyma. This ability strongly increases as roots/OPR develop.

Aquaporins↗

PubMed1997

Opioid peptide receptor stimulation reverses beta-adrenergic effects in rat heart cells.

Opioid peptide receptor (OPR) agonists are co-released with the beta-adrenergic receptor (beta-AR) agonist norepinephrine (NE) from nerve terminals in the heart during sympathetic stimulation. Whereas recent studies indicate that OPR and beta-AR coexist on the surface of cardiac myocytes, whether significant "cross talk" occurs between OPR and beta-AR signaling cascades within heart cells is unknown. In the present study we demonstrate a marked effect of delta-OPR stimulation to modulate beta-adrenergic responses in single isolated rat ventricular myocytes. Nanomolar concentrations (10(-8) M) of the OPR agonist leucine enkephalin (LE), a naturally occurring delta-opioid peptide, inhibited NE-induced increases in sarcolemmal L-type Ca2+ current, cytosolic Ca2+ transient, and contraction. The antiadrenergic effect of LE was pertussis toxin sensitive and abolished by naloxone, an opioid receptor antagonist. In contrast, LE was unable to inhibit the positive inotropic effects induced by equipotent concentrations of 8-(4 chlorophenylthio)-adenosine 3',5'-cyclic monophosphate, a cell-permeant adenosine 3',5'-cyclic monophosphate analog, or by the non-receptor-induced increase in contraction by elevated bathing Ca2+ concentration. These results indicate that an interaction of the OPR and beta-AR systems occurs proximal to activation of the adenosine 3',5'-cyclic monophosphate-dependent protein kinase of the beta-AR intracellular signaling pathway. This modulation of beta-adrenergic effects by OPR activation at the myocyte level may have important implications in the regulation of cardiac Ca2+ metabolism and contractility, particularly during the myocardial response to stress.

Adrenergic beta-Agonists↗

PubMed1996

Variables related to increased mortality following out-patient pulmonary rehabilitation.

Although patients with advanced pulmonary diseases have significant improvement in exercise ability and functional status following comprehensive out-patient pulmonary rehabilitation (OPR), their long-term prognosis once they have reached this stage of their diseases remains poor. To further evaluate predictors of increased mortality in these patients, we related patient characteristics and short-term outcome obtained during OPR assessment of 158 patients to subsequent survival. The time period from OPR to death or collection of survival data was 40.0 +/- 17.1 months. The following variables were tested individually and in stepwise fashion using a proportional hazards model: 1) age; 2) gender; 3) pulmonary diagnosis; 4) prebronchodilator forced expiratory volume in one second (FEV1); 5) arterial oxygen tension (Pa,O2) and arterial carbon dioxide tension (Pa,CO2); 6) body mass index (BMI); 7) pre- and post-OPR 12 min walking distance (12-MW); 8) pre- and post-OPR quality of life, using the Chronic Respiratory Disease Questionnaire (CRDQ); 9) number and type of nonpulmonary diagnoses; and 10) number of medications. Separate survival analyses were performed for all deaths (the total group), respiratory deaths only (nonrespiratory deaths excluded), and nonrespiratory deaths only (respiratory deaths excluded). Forty three patients (27%) died during the study period; and the 3 year survival was 80%. For all three survival analyses, the post-OPR 12-MW was the most significant variable related to prognosis: patients with low timed walking distance had increased mortality both from respiratory and nonrespiratory causes. Other variables related to increased mortality included: elevated Pa,CO2; low pre-OPR 12-MW; reduced Pa,O2; low FEV1; low BMI, increased number of medications, and increased CRDQ dyspnoea. These results indicate that the timed walking distance following out-patient pulmonary rehabilitation is an important predictor of survival in patients with advanced pulmonary disease.

Aged↗

PubMed1993

The long-term benefits of outpatient pulmonary rehabilitation on exercise endurance and quality of life.

Although it is generally accepted that outpatient pulmonary rehabilitation (OPR) improves exercise performance and quality of life (QOL), it is not well established whether these gains are sustained over time. To evaluate this, we attempted to contact the 71 patients who had completed our 6-week OPR program for follow-up 12-min walking distance (12 MD) and QOL measurements. Fifty-one patients (71.8 percent) returned for follow-up testing 11.0 +/- 6.1 months following OPR. Of these, 19 had participated in a structured post-OPR exercise maintenance (EM) program, while 32 had not (non-EM). The 12 MD increased from 2,300 +/- 611 ft at baseline to 2,789 +/- 622 ft post-OPR, while the QOL (higher is better) increased from 81.2 +/- 21.4 to 104.7 +/- 22.2 over this period (both, p < 0.0001). Although the 12 MD decreased by 10.6 +/- 15.8 percent to 2,539 +/- 803 ft at follow-up (p < 0.001), it remained 10.3 +/- 23.4 percent greater than baseline (p < 0.001). Similarly, despite decreasing by 7.6 +/- 13.6 percent to 96.4 +/- 23.3 (p < 0.005), the follow-up QOL remained 22.8 +/- 35.0 percent greater than baseline (p < 0.005). The post-OPR to follow-up declines in 12 MD and QOL were not significantly different between EM and non-EM patients. Thus, only a portion of the initial improvement in exercise endurance and QOL is lost at follow-up months later. Post-OPR EM did not appear to provide measurable long-term advantages.

Aged↗