Changes In EP Research Articles

Pendular energy transduction within the step in human walking.

During walking, the centre of mass of the body moves like that of a 'square wheel': with each step cycle, some of its kinetic energy, E(k), is converted into gravitational potential energy, E(p), and then back into kinetic energy. To move the centre of mass, the locomotory muscles must supply only the power required to overcome the losses occurring during this energy transduction. African women carry loads of up to 20% of their body weight on the head without increasing their energy expenditure. This occurs as a result of an unexplained, more effective energy transduction between E(k) and E(p) than that of Europeans. In this study we measured the value of the E(k) to E(p) transduction at each instant in time during the step in African women and European subjects during level walking at 3.5-5.5 km h(-1), both unloaded and carrying loads spanning 20-30% of their body weight. A simulation of the changes in E(k) and E(p) during the step by sinusoidal curves was used for comparison. It was found that loading improves the transduction of E(p) to E(k) during the descent of the centre of mass. The improvement is not significant in European subjects, whereas it is highly significant in African women.

Photosynthetic acclimation to photon irradiance and its relation to chlorophyll fluorescence and carbon assimilation in the halotolerant green alga Dunaliella viridis.

This work describes the long-term acclimation of the halotolerant microalga Dunaliella viridis to different photon irradiance, ranging from darkness to 1500 mumol m(-2) s(-1). In order to assess the effects of long-term photoinhibition, changes in oxygen production rate, pigment composition, xanthophyll cycle and in vivo chlorophyll fluorescence using the saturating pulse method were measured. Growth rate was maximal at intermediate irradiance (250 and 700 mumol m(-2) s(-1)). The increase in growth irradiance from 700 to 1500 mumol m(-2) s(-1) did not lead to further significant changes in pigment composition or EPS, indicating saturation in the pigment response to high light. Changes in Photosystem II optimum quantum yield (F(v)/F(m)) evidenced photoinhibition at 700 and especially at 1500 mumol m(-2) s(-1). The relation between photosynthetic electron flow rate and photosyntetic O(2) evolution was linear for cultures in darkness shifting to curvilinear as growth irradiance increased, suggesting the interference of the energy dissipation processes in oxygen evolution. Carbon assimilation efficiencies were studied in relation to changes in growth rate, internal carbon and nitrogen composition, and organic carbon released to the external medium. All illuminated cultures showed a high capability to maintain a C:N ratio between 6 and 7. The percentage of organic carbon released to the external medium increased to its maximum under high irradiance (1500 mumol m(-2) s(-1)). These results suggest that the release of organic carbon could act as a secondary dissipation process when the xanthophyll cycle is saturated.

The role of nitric oxide and prostaglandin signaling pathways in spinal nociceptive processing in chronic inflammation

Both nitric oxide (NO) and prostaglandins (PG) and their associated enzymes nitric oxide synthases (NOS) and cyclooxygenases (COX) (specifically COX-2) have been implicated in the development of hyperalgesia. This study examined the effects of naturally occurring chronic inflammation, chronic mastitis, on spinal nociceptive processing in sheep and focused on potential alterations in spinal PG and NO signaling pathways. Mechanical withdrawal thresholds were significantly lower in animals suffering from chronic inflammation ( n=6) compared to control animals ( n=6). Hyperalgesia was restricted to the side contralateral to the inflammation (decrease from ipsilateral side: hindlimb 33.2±5%, forelimb 19.4±5%). Neuronal NOS-immunoreactivity was significantly reduced bilaterally in lumbar and cervical spinal cord throughout laminae I–III (decrease 18.4±5% and 16.9±4%, respectively) and in lamina X (decrease 29.1±6% and 17.1±4%, respectively) in mastitic animals relative to control animals. No difference was detected in eNOS or iNOS-immunoreactivity or in NADPH-diaphorase staining, a marker of dynamically active NOS. RT-PCR failed to detect any change in levels of nNOS, eNOS, iNOS, COX-1 or COX-2 mRNAs. However, a marked increase in the PGE receptor, EP 3 (but not EP 2) mRNA was detected in ipsilateral spinal cord tissue from animals with chronic inflammation. This increase in EP 3 receptor expression indicates that spinal PGs are important in the spinal response to chronic peripheral inflammation. Contralateral mechanical hyperalgesia may not be directly linked to changes in spinal EP 3 receptor mRNA expression, however, the bilateral changes in nNOS suggest that this pathway may contribute to the adaptive behavioural response observed.

ARE HIGH ELEVATIONS IN TROPICAL MOUNTAINS ARID ENVIRONMENTS FOR PLANTS?

Plants growing at high elevations in tropical mountains show a scleromorphic habit at the leaf and plant level, despite the fact that alpine landscapes are generally considered to be cool and humid environments. This paper tests the hypotheses (1) that aridity (potential transpiration Ep/rainfall P) in tropical alpine environments can be high despite low temperatures, and (2) that aridity in tropical alpine environments may be correlated with scleromorphic habit. A leaf energy balance model was developed that calculates the change in Ep for a standard leaf along elevational transects in equatorial and middle-latitude mountains by accounting for pressure (elevation) and temperature effects on transpiration. Modeled leaf-level transpiration in tropical alpine environments can be substantial and may even exceed transpiration at low elevations in middle latitudes. At 5000 m elevation, a high diffusion coefficient for water vapor under low air pressure and a high radiation load result in Ep rates 50–90% higher in tropical mountains than in middle-latitude ones. High Ep rates at high elevations are expected (1) in mountains of the dry tropics with low cloudiness and low rainfall but high radiation and, (2) in small oceanic mountain ranges with a strong advection of moist air and, thus, a reduced temperature lapse rate on the slope. Data from tropical Mount Haleakala (Maui, Hawaii) and from the middle-latitude Tyrolian Alps (Austria) were used to test the predicted Ep rates. The two mountains sharply contrast with respect to vertical distribution of Ep and rainfall. At high elevation on Maui, the calculated Ep was high (and was consistent with measured atmometer evaporation rates Em), whereas rainfall was moderate to low. At high elevation in the Alps, both Ep and Em were low compared to similar elevations on Maui, but rainfall was high. Worldwide mountain climate data sets show that rainfall tends to decrease upslope in many tropical mountains, while it increases with elevation in most middle-latitude mountains. I conclude that (1) high-elevation environments in tropical mountains are more arid than similar elevations in middle-latitude mountains as a result of both higher evaporative demand and lower rainfall, and (2) that aridity can significantly contribute to the scleromorphy of tropical alpine plants which had previously been attributed to low temperature or high radiation effects alone.

534. Reduction of psychotic symptoms in patients with Lewy body-like symptoms treated with olanzapine

A double-blind 6-week study of nursing home patients (n 5 206) with moderate to severe dementia indicated that 5 mg/day olanzapine provided superior efficacy compared to placebo in reducing psychosis and behavioral disturbances associated with Alzheimer’s disease. Additional analyses assessed the effect of 5 mg/day olanzapine relative to placebo on psychosis and EPS in patients who had possible dementia with Lewy bodies (n 5 29) determined by a nonzero score on the Simpson-Angus Scale, a nonzero score on the Hallucinations item of the NPI/NH and no reported neuroleptic use prior to study entry. Patients treated with olanzapine had a 82.9% mean improvement in the NPI/NH Delusions and Hallucinations combined score compared to a 17.4% mean improvement for placebo (p 5 .015). On the NPI/NH Delusions item, olanzapine-treated patients had a 77.8% mean improvement, compared to a 29.0% mean improvement for placebo (p 5 .012). For all psychiatricrelated NPI/NH items, olanzapine produced at least a 3-fold improvement in scores relative to placebo. In addition, the olanzapine-treated group had an 85.7% improvement in Occupational Disruptiveness related to the NPI/NH Delusions and Hallucinations combined items while the placebo-treated group had only a 14.0% improvement (p 5 .002). Significant improvement (p 5 .042) was also found on the Mini-Mental State Exam for patients treated with olanzapine (2.4-point mean improvement) compared to placebo (0.1-point mean worsening). Changes in EPS were not clinically significantly different for patients treated with olanzapine compared to placebo.

Prostaglandin receptors in lower segment myometrium during gestation and labor

Objective: To determine if expression of relaxatory prostaglandin (PG) E 2 receptors (EP 2 isoform) and contractile PG F receptors (FP isoform) changes during gestation and with labor in pregnant human myometrium. Methods: Lower segment myometrium was removed at cesarean from four groups of parturients (preterm [28–36 weeks] or term [37–41 weeks], either in or not in labor, ten per group). Myometrial RNA was isolated and used for reverse transcription-polymerase chain reaction (PCR) analysis with specific primer sets for human smooth muscle protein calponin and PGEP 2 or FP receptor isoform mRNA. Polymerase chain reaction products were electrophoresed on gels and visualized, band intensity was measured, and EP 2 and FP receptor expression was normalized to calponin. Results: Reverse transcription-PCR yielded products of expected sizes, and restriction enzyme cleavage confirmed identities. Prostaglandin EP 2 receptor isoform mRNA expression (relative to calponin mRNA) was significantly greater in the preterm, no labor group (1.28 ± 0.22, mean ± standard error of the mean [SE]) compared with the term, no labor group (0.71 ± 0.09) ( P < .05 Student-Neuman-Kuels) and declined significantly with gestational age in patients not in labor ( R = −.446, P = .001). Prostaglandin FP receptor isoform mRNA expression was significantly less in the term, no labor group (0.61 ± 0.06) compared with all others ( P < .02 Student-Neuman-Kuels). Prostaglandin FP receptor expression declined significantly with gestational age in patients not in labor ( R = −.646, P = .012) and increased significantly with labor at term. Conclusion: Changes in prostaglandin EP 2 receptor isoform expression are consistent with influence on maintenance of quiescence. Labor at term is associated with a significant increase in FP receptor expression, consistent with influence on contraction. The balance between the two receptor isoforms might mediate myometrial contractility.

P50 Changes with Visual Interference in Normal Subjects: A Sensory Distraction Model for Schizophrenia

Twenty-five normal subjects were tested in a Conditioning-Testing (S1-S2) auditory P50 study. Each subject was tested twice under two experimental conditions: distraction condition (with light interference) and control condition (without interference). Results showed that S1 P50 amplitude was significantly decreased with visual interference compared with that in the control condition, while the S2 response remained unchanged. Consequently, the S2/S1 gating ratio was also increased remarkably in the distraction condition. The auditory EP changes with the visual distraction in normals closely resembled the abnormal findings in schizophrenic subjects. These data may provide an alternative model to elucidate the psychophysiological mechanism that possibly rules the changes of attention in schizophrenia.

Enhanced cochlear responses after sound exposure

Hensen’s cell alternating potentials were recorded in the gerbil cochlea by means of the approach developed previously in this laboratory. An intensity series of magnitude and phase transfer functions (TFs) and cochlear microphonic (CM) TFs from 125 Hz to 16 kHz were obtained at 40–90 dB sound pressure level (SPL) by means of frequency sweeps. Subsequently, the same frequency sweeps at either 80, 90, or 100 dB SPL were delivered to the ear for 10–40 min. CM, Hensen’s cell TFs, and EP were monitored periodically post-exposure. Hensen’s cell responses showed enhancement within 40–50 min post-exposure and a phase lead. There was no correlation between changes in peak response and changes in receptor potential or EP. The response enhancement and its associated phase lead is explained with the help of Zwislocki’s cochlear model [Mechanics and Biophysics of Hearing, edited by P. Dallos (Springer-Verlag, Berlin, 1990)]. Since Hensen’s cells cannot generate receptor potentials by themselves, and their AC potentials have been shown to be directly proportional to those of OHCs, the measured enhancement appears to reflect enhanced OHC responses. [Work supported by NIDCD.]

Effects of ketorolac tromethamine on erythropoietin levels in Sprague Dawley rats

Ketorolac tromethamine (KT) is a potent analgesic, most often used in its injectable form postoperatively. Similar to other nonsteroidal antiinflammatory drugs (NSAIDs), it inhibits prostaglandin (PG) synthesis. Prostaglandins have been shown to be involved in the regulation of renal function as well as erythropoietin (Ep) production. The intent of this study was to determine the effect of KT on plasma Ep levels in Sprague Dawley (SD) rats. Twenty rats received either 15 mg/kg/d or the KT vehicle IM for 5d. Blood samples (1 ml) were collected via tail vein each day of treatment. Plasma Ep levels were significantly higher in the KT rats than normal controls with the greatest difference occurring on d4 of treatment (70.1 +/- 10.8 vs 30.9 +/- 10.84 mU/ml, p < 0.01). This change in Ep corresponded with a significant reduction in hematocrit (KT, 29.5 +/- 2.2 vs C, 40.8 +/- 2.2%, p < 0.01). Presence of fecal blood was noted in the KT treated rats. A similar second experiment was designed to determine if blood loss was the cause of altered Ep production. In this experiment controls (HC) were bled via tail vein, to match the hematocrits of KT treated animals. Repeated administration of KT led to a steady reduction in hematocrit. When compared, hematocrit matched animals showed no difference in plasma Ep levels on all days of treatment (KT, 48.0 +/- 4.9 vs HC, 44.6 +/- 3.1 mU/ml, N.S.). In conclusion, repeated administration of KT showed no impairment of Ep production and release in response to reduced hematocrit, suggesting that in this instance, prostaglandin inhibition plays a minimal role in Ep production or release.

Insulin, C-peptide, androgens, and beta-endorphin response to oral glucose in patients with polycystic ovary syndrome.

We examined the effects of an oral glucose load on plasma insulin, androgens, and beta-endorphin (beta EP) concentrations in patients carefully selected as having polycystic ovary syndrome (PCOS) and normal glucose tolerance. Our aim was to verify whether insulin resistance is a common feature of PCOS and to differentiate the metabolic abnormalities related to PCOS from those associated with obesity. Plasma immunoreactive insulin (IRI), C-peptide (C-PR), testosterone, androstenedione, dehydroepiandrosterone sulfate, ACTH, and beta EP responses to a 3-h oral glucose tolerance test (OGTT) were evaluated in 10 obese (OB-PCOS) and 10 nonobese (NO-PCOS) patients with PCOS and in 7 obese and 7 nonobese ovulatory controls. OB-PCOS and NO-PCOS did not differ significantly from weight-matched controls in the IRI response, but had a significantly higher C-PR response in terms of mean postglucose load levels and mean incremental areas. During OGTT, mean plasma levels of testosterone, androstenedione, and dehydroepiandrosterone sulfate declined in both PCOS groups as well as in controls, and no significant correlation between the plasma androgen and IRI or C-PR responses was found. The ACTH response in OB-PCOS and NO-PCOS was similar to that in controls, with a progressive decrease until 180 min. A similar decline in plasma beta EP was found in controls, whereas no change in plasma beta EP was observed in OB-PCOS and NO-PCOS. These findings indicate that independently of the presence of obesity, PCOS patients have enhanced insulin secretion in response to OGTT and show a peculiar pattern of changes in plasma beta EP.

低酸素状態におけるか牛血流量の動態とＥＰの変化

低酸素状態におけるか牛血流量の動態とＥＰの変化

Effects of K +-channel blockers on cochlear potentials in the guinea pig

The effects of different K + channel blockers, 4-aminopyridine (4-AP), tetraethylammonium (TEA) and quinine, on the various cochlear potentials were observed by the means of perilymph infusion. Each of the three blockers depressed the compound action potential. However, they exerted quite different effects on other cochlear potentials, especially comparing 4-AP, a fast K +-channel blocker, with two other blockers. 4-AP induced a significant increase in the magnitude of summating potential, while TEA and quinine decreased it; 4-AP showed no effect on the general endocochlear potential (G-EP, the EP value recorded directly from the scala media, SM) and the negative EP component (N-EP), while TEA and Quinine increased G-EP and decreased the absolute value of N-EP. They also exerted different effects on the EP changes induced by exposure to intense noise. The results indicate the different roles of different K +-channels in the generation of cochlear potentials. The relationship of the two components of EP (positive and negative) and the G-EP was discussed.

Potential evapotranspiration and the likelihood of future drought

The likelihood of future drought is studied on the basis of two drought indices calculated from the Goddard Institute for Space Studies general circulation model (GISS GCM) transient and doubled CO2 climate changes. We use the Palmer drought severity index (PDSI) and a new supply‐demand index (SDDI), the latter being the difference between the precipitation and potential evapotranspiration Ep, i.e., the difference between atmospheric supply of and demand for moisture. Both indices show increasing drought for the United States during the next century, with effects becoming apparent in the 1990s. If greenhouse gas emissions continue to increase rapidly, the model results suggest that severe drought (5% frequency today) will occur about 50% of the time by the 2050s. The results are driven by the large increase in EP, associated with the simulated climate warming. EP increases most where the temperature is highest, at low to mid‐latitudes, while precipitation increases most where the air is coolest and easiest to saturate by the additional moisture, at higher latitudes. Thus atmospheric demand becomes greater than supply for most of the globe by the latter half of next century. We show that large EP changes can lead to soil moisture deficits, as in the PDSI hydrologic budget, and vegetation desiccation, as is implied by vegetation and climate models. We suggest that drought intensification has been understated in most GCM simulations, including the GISS GCM, because of their lack of realistic land surface models. Paleoclimate analogues in the Mesozoic and Cenozoic are reviewed which imply that arid conditions can result from either increased temperatures or decreased precipitation, consistent with our use of the SDDI. The results depend primarily on the temperature increase, in particular the model sensitivity of 4°C warming for doubled CO2. Global precipitation cannot keep pace with increased demand over land because the land surface warms more than the ocean surface; this effect, along with greater atmospheric opacity, reduces low level gradients and evaporation from the ocean. If the forecast temperature changes come to pass, these conclusions suggest that drought conditions will increase dramatically.

Ｐｈｅｎｙｔｏｉｎ Ｎａｔｒｉｕｍの抗耳鳴作用に関する臨床的並びに電気生理学的検討

Anticonvulsant drugs like Carbamazepine and Phenytoin natrium (PHT) have been used for suppressing the tinnitus. In this paper, a clinical experience was reported, in that 100 patients with tinnitus were treated with intravenous administration of PHT, and the influence of PHT on auditory systems in the guinea pig investigated in detail electrophysiological examinations was also reported. The results are summarised as follows: 1. Clinical evaluation in the treatment of tinnitus (1) Of the 100 patients, more than 70% were well responded. (2) Pith match, loudness balance test correlated closely with the suppression of tinnitus. (3) Side effects were found in 5%, but there were all mild enough to be well tolerated. 2. Experimental evaluation in the guinea pig (1) In intravenous administration of PHT, latency and amplitude of each waveform peak in ABR were prolonged and decreased. As for the latency, waves III and IV were most prominently affected. The results may indicated that PHT works in the upper brain stem predominantly and effects also to the cochlear nucleus and cochlear nerve. (2) The amplitude of N1 in AP was depressed and its latency was slightly prolonged. These phenomena related closely with change of wave I in ABR. This may indicate that PHT can directly suppress the cochlear nerve. (3) Even at the dose that apparently influenced ABR and N1 in AP, no obvious change was observed on amplitudes in CM and EP, that may indicate PHT cannot affect on hair cells at this dose or it cannot proceed to the cochlea. (4) These changes were considered to be direct effect of PHT on auditory systems, since they were not correlated with change in the circulatory system. (5) In the perilymphatic perfusion of PHT, amplitudes in EP and CM were depressed slightly at the beginning of the perfusion. Changes in EP preceded those in CM. The results may indicate that PHT effects directly on the stria vascularis and secondarily on CM. (6) In this perfusion, no obvious change was found in AP. Nevertheless, the amplitude of N1 in AP increased over the initial level after the perfusion corresponding to the recovery of EP in some animals. The results may indicate that PHT cannot work directly on hair cells nor cochlear nerve and that the suppression of efferent inhibitory neurons can increase AP potentials. (7) PHT works on the large part of auditory pathway without cochlea, as a role of inhibitor. Considering antitinnitic effect of PHT, tinnitus bases on unusual excitement of the auditory pathway.

Changes in EP during Indomethacin Perilymphatic Perfusion

Changes in EP during Indomethacin Perilymphatic Perfusion

Pregnancy and birth complications and premorbid functioning in schizophrenic and bipolar patients

(4 HIV , 14 HIV + asymptomatic, 6 HIV + symptomatic) and 17 ageand sexmatched normal controls. Standard BSAER, VEP and Auditory Event Related Potential (AERP) methodology (P300) showed a prolongation of the BSAER I-V latency, of the VEP PlOO latency and of the AERP P300 latency in the three patient groups as compared to controls. There was no significant difference in these measures between the HIV , asymptomatic HIV+ or symptomatic HIV+ groups. Substance abuse should be carefully controlled for before EP changes are attributed to HIV infection.

Changes in EP during Nifedipine Perilymphatic Perfusion

Changes in EP during Nifedipine Perilymphatic Perfusion

EP Change in Experimental Round Window Rupture

EP Change in Experimental Round Window Rupture

Einfluß des Lichtangebotes auf das Wachstum und die biologische Stickstoff‐Fixierung von Weißklee (Trifolium repens L.)

AbstractInfluence of light quantity on growth and biological nitrogen fixation of white clover (Trifolium repens L.)The influence of photon irradiance (Ep; 100 to 500 μmol m−2 s−1) and of the photoperiod (16 or 11 h) on growth and nitrogenase activity of nodulated white clover plants was studied in growth chambers at two nitrate levels (1.0 and 7.5 mM NO3−).Total dry mass production, the root proportion and nitrogenase activity increased with increasing Ep and photoperiod. Nitrogenase activity generally increased proportionally to root mass. Only at low Ep (100 μmol m−2 s−1) and under a short photoperiod (11 h) was the specific nitrogenase activity per unit root mass reduced. An abrupt change in Ep led to a rapid and parallel change in nitrogenase activity and relative growth rate.A higher NO3− concentration in the nutrient solution (7.5 mM) led to a marked decrease in specific nitrogenase activity, but increased growth between 200 and 500 μmol m−2 s−1 during early development only. At 100 μmol m−2 s−1, there was no growth response to nitrate, although its effect on nitrogenase activity was more marked than at a higher Ep.The results show that with changing light quantity, biological nitrogen fixation of white clover adapts to the existing demand for nitrogen and does not limit growth except during early development, even when light supply is low.

Antagonistic action of reductants against vanadate-induced EP decrease.

The antagonistic action of ascorbic acid or glutathione against vanadate was studied by observing changes in EP in guinea pig cochlea. After intravenous injection of ascorbic acid or glutathione, the EP decrease induced by perfusion of the perilymphatic space with vanadate solution was suppressed and the EP showed a remarkable recovery in some animals. Intravenous preadministration of either of the two compounds inhibited or prevented the vanadate-induced EP decrease. When ascorbic acid or glutathione was added to the vanadate solution, the EP decrease was also inhibited. The chemical action of both reductants against vanadate is discussed. From the results obtained, it is speculated that a chemical balance between some oxidants and reductants in the stria vascularis, must be kept constant in order to maintain the EP at a constant potential level.