Capability of CI-Orbitrap for Gas-Phase Analysis in Atmospheric Chemistry: A Comparison with the CI-APi-TOF Technique.

Chemical ionization Orbitrap mass spectrometry (CI-Orbitrap) represents a promising new technique for gas-phase analysis in analytical and atmospheric chemistry mainly due to its very high mass resolving power. In this work, we performed the first side-by-side comparison between a CI-Orbitrap and the widely used atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF) using two different chemical ionization methods, i.e., acetate-ion-based (CH3COO-) and aminium-ion-based (n-C3H7NH3+) schemes. The capability of the CI-Orbitrap at accurately measuring low concentrations of gaseous species formed from the oxidation of α-pinene was explored. Although this study reveals a lack of linearity of the CI-Orbitrap when measuring product ions at very low concentrations (<1 × 106 molecules cm-3), very good agreement between both techniques can be achieved by applying a newly developed linearity correction. It is experimentally shown that the correction function is independent of the reagent ion used. Thus, accurate quantification of organic compounds at concentrations as low as 1 × 105 molecules cm-3 by the CI-Orbitrap can be achieved. Finally, by means of tandem mass spectrometry, the unique capability of the Orbitrap allows the direct determination of the binding energy of cluster ions between analyte and reagent ions, that is needed for the assessment of a chosen ionization scheme.

Fast Peroxy Radical Isomerization and OH Recycling in the Reaction of OH Radicals with Dimethyl Sulfide.

Dimethyl sulfide (DMS), produced by marine organisms, represents the most abundant, biogenic sulfur emission into the Earth's atmosphere. The gas-phase degradation of DMS is mainly initiated by the reaction with the OH radical forming first CH3SCH2O2 radicals from the dominant H-abstraction channel. It is experimentally shown that these peroxy radicals undergo a two-step isomerization process finally forming a product consistent with the formula HOOCH2SCHO. The isomerization process is accompanied by OH recycling. The rate-limiting first isomerization step, CH3SCH2O2 → CH2SCH2OOH, followed by O2 addition, proceeds with k = (0.23 ± 0.12) s-1 at 295 ± 2 K. Competing bimolecular CH3SCH2O2 reactions with NO, HO2, or RO2 radicals are less important for trace-gas conditions over the oceans. Results of atmospheric chemistry simulations demonstrate the predominance (≥95%) of CH3SCH2O2 isomerization. The rapid peroxy radical isomerization, not yet considered in models, substantially changes the understanding of DMS's degradation processes in the atmosphere.

[Arthroscopic subacromial decompression]. / Arthroskopische subakromiale Dekompression.

OBJECTIVE: Coracoacromial ligament release to widen the subacromial space, resection of the anterior undersurface of the acromion and, if needed, caudal exophytes at the acromioclavicular joint. INDICATIONS: All types of outlet impingement after 3 months of conservative treatment. CONTRAINDICATIONS: Impingement syndrome with instability/muscular imbalance, massive rotator cuff tear, unstable os acromionale, posterior-superior impingement, joint infection, freezing phase of a secondary frozen shoulder. SURGICAL TECHNIQUE: Lateral decubitus position with traction device for the arm. Diagnostic arthroscopy of the glenohumeral joint via standard portals. With arthroscope moved to the subacromial space, bursectomy, electrosurgical release of coracoacromial ligament, resection of acromial hook through standard posterior portal. POSTOPERATIVE MANAGEMENT: Physiotherapy or self-exercises on postoperative day 1, pain-adapted analgesia to avoid shoulder stiffness. RESULTS: Several studies present positive long-term results compared to conservative treatment (and open acromioplasty) for partial rotator cuff tears and for elderly patients. With a 20-year follow-up, successful results have been achieved for all patients with isolated impingement syndrome.

[Arthroscopic release for shoulder stiffness]. / Arthroskopische Arthrolyse bei Schultersteife.

OBJECTIVE: Arthroscopic capsular release for refractory shoulder stiffness to recreate active and passive shoulder joint mobility. INDICATIONS: Adhesive capsulitis of the shoulder (primary and secondary frozen shoulder) after receiving at least 3 months of conservative treatment. CONTRAINDICATIONS: Boney-related stiffening of the shoulder joint, joint infection, freezing phase of the primary frozen shoulder and shoulder stiffness after reconstructive surgery. SURGICAL TECHNIQUE: Opening of the lower shoulder joint capsule over a gentle unidirectional manipulation under general anesthesia. A diagnostic arthroscopy in lateral position with extension of the arm is then performed. The release is completed with incision of the ventral and the dorsal part of the capsule under arthroscopic control. POSTOPERATIVE MANAGEMENT: While still in the operation room, the anesthetist places an interscalene brachial plexus catheter, thus, delivering the best possible analgesia. This enables full range of active and passive movement of the shoulder joint for at least 3 days. Outpatient continuation of physiotherapy with anti-inflammatory and analgesic medication. RESULTS: The literature shows good functional results with age- and gender-related Constant scores greater than 75 %. Our retrospective inquiry of 37 cases with a mean follow-up of 40 months confirms this outcome. The disease duration was shortened by arthroscopic release. Ability to work was achieved after a mean of 1.9 months; treatment ended 3.6 months after operation. In 10 cases with secondary shoulder stiffness, residual symptoms remained.

A new atmospherically relevant oxidant of sulphur dioxide.

Atmospheric oxidation is a key phenomenon that connects atmospheric chemistry with globally challenging environmental issues, such as climate change, stratospheric ozone loss, acidification of soils and water, and health effects of air quality. Ozone, the hydroxyl radical and the nitrate radical are generally considered to be the dominant oxidants that initiate the removal of trace gases, including pollutants, from the atmosphere. Here we present atmospheric observations from a boreal forest region in Finland, supported by laboratory experiments and theoretical considerations, that allow us to identify another compound, probably a stabilized Criegee intermediate (a carbonyl oxide with two free-radical sites) or its derivative, which has a significant capacity to oxidize sulphur dioxide and potentially other trace gases. This compound probably enhances the reactivity of the atmosphere, particularly with regard to the production of sulphuric acid, and consequently atmospheric aerosol formation. Our findings suggest that this new atmospherically relevant oxidation route is important relative to oxidation by the hydroxyl radical, at least at moderate concentrations of that radical. We also find that the oxidation chemistry of this compound seems to be tightly linked to the presence of alkenes of biogenic origin.

[Screw arthrodesis of the shoulder]. / Schraubenarthrodese der Schulter.

OBJECTIVE: The aim of the procedure is arthrodesis of the shoulder by osteosynthesis of the glenohumeral and the acromiohumeral joint each with three screws, which results in preservation of scapulothoracic motion and pain relief. INDICATIONS: Traumatic brachial plexus lesions, palsy in infancy, poliomyelitis with preserved or restorable function of the elbow and the hand. Paralysis of the deltoid muscle and the rotator cuff. Nonrestorable vast defect of the rotator cuff with pseudoparalysis. Chronic infectious arthritis resistant to therapy. Unsuccessful attempts to treat glenohumeral instability. Alternative procedure to shoulder arthroplasty in young patients with omarthrosis, who perform hard physical work. CONTRAINDICATIONS: Insufficient strength of the scapular muscles (< grade 4, <75% of normal strength). Insufficient scapulothoracic passive motion. Inadequate soft tissue coverage after burns, excessive previous surgery or radiotherapy. Incomplete rehabilitation (<3 years) after neurosurgical interventions (neurolysis, nerve transplantation). Cases of resection of the proximal humerus. SURGICAL TECHNIQUE: Acampsia of the shoulder joint in 20° of abduction, 30° of anteversion, and 40° of internal rotation using three glenohumeral and three acromiohumeral spongiosa screws as a compression arthrodesis. POSTOPERATIVE MANAGEMENT: Thorax-arm-abduction splint (20° of abduction, 30° of anteversion, and 40° of internal rotation) until the week 6 postoperatively with removal for physiotherapy and personal hygiene. Assisted active and passive motion exercises for the elbow, hand, and fingers after the postoperative day 1. Weaning from the splint after the end of the week 6 postoperatively, full range of motion allowed. RESULTS: In a prospective study from January 2007 to September 2008, 4 patients with a medium age of 35.7 years underwent screw arthrodesis of the shoulder with a follow-up of 1.0 (0.6-1.5) year. Primary fusion of all arthrodesis surfaces was achieved in all patients; no revision surgery was necessary. All patients improved in shoulder function with an average range of motion of 60° abduction and 40° anteversion.

Role of gender on renal interstitial hydrostatic pressure and sodium excretion in rats.

The objective of this study was to compare renal interstitial hydrostatic pressure (RIHP) and sodium excretion in female and male Sprague-Dawley (SD) rats. The RIHP and pressure natriuresis responses were determined in female (n=13) and male (n=8) SD rats. Renal perfusion pressure (RPP) was controlled at two levels (100 and 120 mm Hg). Clearances were taken at each level and RIHP was measured with a chronically implanted polyethylene matrix in all rats. At the lower RPP level, RIHP was similar in both groups of rats (5.2+/-0.2 mm Hg for female, and 5.5+/-0.4 mm Hg for male), whereas fractional excretion of sodium (FENa) was significantly lower (P < .05) in male (1.10+/-0.27%) as compared to female (2.23+/-0.32%) rats at similar lower RPP. Allowing RPP to increase from 100 to 120 mm Hg resulted in similar increases in FENa (deltaFENa), urine flow rate (deltaV), and RIHP (deltaRIHP) in both groups of rats. The deltaFENa, deltaV, and deltaRIHP were 1.67+/-0.43%, 38.45+/-4.74 microL/min/g kidney weight, and 2.7+/-0.2 mm Hg for female, and 1.79+/-0.42%, 30.40+/-4.37 microl/min/g kidney weight, and 2.8+/-0.3 mm Hg for male rats. In conclusion, RIHP is similar in female and male SD rats at similar RPP levels. Both female and male SD rats increase RIHP and sodium excretion similarly in response to increases in RPP. The lower basal FENa in male as compared to female rats may play an important role in the more significant elevation of blood pressure in males with age.

Role of plasma renin activity and the renal nerves in the natriuresis of L-NMMA infusion in rats.

The objective of this study was to determine the effect of N(G)-monomethyl-L-arginine (L-NMMA) infusion on plasma renin activity (PRA) in the presence or absence of the renal nerves in normotensive Wistar-Kyoto (WKY) rats and Okamoto spontaneously hypertensive rats (SHR). All rats were unilaterally nephrectomized two weeks before the acute experiment. On the day of the experiment, acute renal denervation (Dnx) of the remaining kidney was performed in one group of WKY rats (Dnx-WKY; n= 10) and one group of SHRs (Dnx-SHR: n=7). The renal nerves were left intact in a group of WKY rats (Inn-WKY; n=8) and SHRs (Inn-SHR; n=9). After a control clearance period, L-NMMA was administered i.v. (15 mg/kg bolus followed by 500 microg/kg/min infusion) and another clearance period of 20 min was taken. In all experimental groups L-NMMA infusion resulted in a significant natriuresis. L-NMMA infusion increased fractional excretion of sodium (FE(Na)) to a greater extent in the Inn-SHR than in the Inn-WKY (delta FE(Na) = 5.23+/-0.87% vs delta FE(Na) = 2.87+/-0.73% respectively; P=0.05), PRA did not change in the SHR with the infusion of L-NMMA. However, in the Inn-WKY group, the natriuresis of L-NMMA infusion was associated with a tendency for lower PRA levels as compared to a group of time control Inn-WKY rats. In Dnx-WKY, the natriuresis of L-NMMA infusion (delta FE(Na) = 4.60+/-0.52%) was associated with a significantly lower level of PRA (4.26+/-1.18 ng AI/ml/hr) as compared to a group of time control Dnx-WKY rats (9.83+/-1.32 ng AI/ml/hr; P<0.05). In the Dnx-SHR, the natriuretic response to L-NMMA infusion was significantly attenuated by renal denervation (delta FE(Na) = 2.36+/-0.34%) and PRA was unchanged. In conclusion, the natriuretic effect of systemic inhibition of nitric oxide (NO) synthesis was associated with decreased PRA in the Dnx-WKY suggesting that a potential interaction exists between NO and the renal nerves in the modulation of PRA in the normotensive WKY rat. Whereas, the natriuretic effect of L-NMMA infusion in the SHR in the presence and absence of the renal nerves, were independent of changes in PRA.

Mechanism underlying diuretic effect of L-NAME at a subpressor dose.

The diuretic effects of nitric oxide (NO) synthase inhibitors administered at subpressor dose in rats are controversial, and the tubular segments involved are not known. In the present study, we examined the effect of N(omega)-nitro-L-arginine methyl ester (L-NAME) at a subpressor dose on renal interstitial NO and cGMP activity and on renal tubular segmental reabsorption of fluid in the rat. Intravenous infusion of L-NAME at 1 microg. kg(-1). min(-1) in Sprague-Dawley rats (N = 8), which did not alter mean arterial pressure or glomerular filtration rate, significantly increased urine flow rate (U(v); from 78.2 +/- 12.7 to 117.1 +/- 14.9 microl/min, P < 0.05). Paradoxically, this effect of L-NAME was concomitant with significant increases in nitrite/nitrate (from 10.79 +/- 1.20 to 16.50 +/- 2.60 microM, P < 0.05) and cGMP (from 0.65 +/- 0.09 to 0.98 +/- 0.18 nM, P < 0.05) concentrations in renal cortical microdialysate as well as the nitrite/nitrate concentration in the medullary microdialysate. Micropuncture studies in the superficial nephron revealed that L-NAME significantly increased the flow rate (from 8.3 +/- 0.9 to 12.2 +/- 1.2 nl/min, P < 0.05) and fractional delivery of fluid to the distal tubule, but not those in the late proximal tubule. In conclusion, L-NAME, at the subpressor dose used in this study, increased renal nitrate/nitrite and cGMP and inhibited fluid reabsorption in tubular segments between the late proximal tubule and the distal tubule of superficial nephrons.

Intrarenal serotonin, dopamine, and phosphate handling in remnant kidneys.

BACKGROUND: Serotonin (5-HT) and dopamine (DA) are intrarenal autocrine/paracrine substances that regulate phosphate reabsorption. The present studies explored intrarenal serotonin and DA metabolism and the implications for phosphate homeostasis in rats with remnant kidneys, a model for renal failure. METHODS: The intrarenal productions of serotonin and DA were determined from measurements of renal interstitial fluid (microdialysate) and urine in rats with remnant or intact kidneys. In clearance studies, the effects of infusion of methiothepin, a serotonin receptor antagonist, or gludopa, a renal selective DA precursor, on phosphate and sodium excretion were determined in rats with a remnant or intact kidneys. RESULTS: Renal interstitial serotonin (5-HT, 3.4 +/- 0.9 pg/min) was fourfold higher than DA (0.6 +/- 0.1 pg/min) in remnant kidneys. Conversely, urinary excretion of serotonin was fourfold less than DA in rats with a remnant kidney (5-HT 0.4 +/- 0.02 vs. DA 1.5 +/- 0.1 ng/min). Infusion of methiothepin or gludopa significantly increased the fractional excretion of phosphate (FE(Pi)) in rats with a remnant kidney from 54 +/- 3 to 67 +/- 7% (P < 0.05) and from 36 +/- 10% to 51 +/- 13% (P < 0.05), respectively. CONCLUSION: We conclude that serotonin preferentially accumulates in the renal interstitium, whereas DA exits primarily via the tubular lumen. Phosphate excretion is increased by both the acute infusion of the serotonin receptor antagonist and the infusion of gludopa, suggesting that both serotonin and DA modulate phosphate excretion in rats with remnant kidneys.

Effect of inhibition of MAO and COMT on intrarenal dopamine and serotonin and on renal function.

The purpose of the present investigation was to study the effects of inhibition of monoamine oxidase (MAO) and/or catechol-O-methyltransferase (COMT), enzymes involved in the degradation of dopamine (DA) and serotonin (5-HT), on intrarenal DA and 5-HT, as reflected in the renal interstitial fluid (RIF) microdialysate and urine, and on renal function. Inhibition of MAO selectively increased RIF 5-HT from 3.16 +/- 0.38 to 8.03 +/- 1.83 pg/min (n = 7, P < 0.05), concomitant with decreases in mean arterial blood pressure and glomerular filtration rate (2.09 +/- 0. 18 to 1.57 +/- 0.22 ml/min, n = 7, P < 0.05). Inhibition of COMT significantly increased RIF DA (3.47 +/- 0.70 to 8.68 +/- 1.96 pg/min, n = 9, P < 0.05), urinary DA (2.00 +/- 0.16 to 2.76 +/- 0.26 ng/min, n = 9, P < 0.05), and absolute excretion of sodium (6.42 +/- 2.00 to 9.82 +/- 1.62 micromol/min, n = 10, P < 0.05). Combined inhibition of MAO and COMT significantly increased RIF DA, urinary DA, and urinary 5-HT, which was accompanied with increases in urine flow rate, and absolute (3.03 +/- 0.59 to 8.40 +/- 1.61 micromol/min, n = 9, P < 0.01) and fractional excretion of sodium. We conclude that inhibition of MAO selectively increases RIF 5-HT. COMT appears to be more important than MAO in the metabolism of intrarenal DA. Physiological increases in intrarenal DA/5-HT induced by inhibition of their degrading enzymes are accompanied with significant alterations of renal function.

Role of HSP70i in regulation of biomaterial-induced activation of human monocytes-derived macrophages in culture.

The functioning of an implant depends on the material properties and the wound-healing process. The latter is led by an inflammatory reaction guided mainly by monocyte/macrophage activity. This in vitro study investigated human monocytes/macrophages in culture from 2 h to 10 days on silicone, polyurethane, teflon and TCPS. Analysis of cytokine release by ELISA showed that maturing macrophages have different capacities to produce cytokines TNFalpha, IL10, IL8 and GM-CSF. The long culture-mature macrophages on all polymers produced comparable low levels of TNFalpha, IL10 and IL8. Monocytes/macrophages on polyurethane and teflon, and those on silicone only in long culture-time produced high GM-CSF amounts, where as those on TCPS exhibited low levels of GM-CSF. FACS analysis revealed that HSP70i was highly inducible after short time culture yet this high level was maintained in long culture-mature macrophages on TCPS only, whereas on other polymers the mature macrophages showed a high reduction in HSP70i level, which demonstrated a high stress-response by cells on TCPS. Accordingly, CLSM-analysis revealed low nuclear NF-kappaB in cells on TCPS and high nuclear NF-kappaB in mature macrophages on silicone and polyurethane, showing a high cellular activation on the latter two polymers. This corresponded also to the high mitochondrial activity by XTT metabolism displayed by the mature macrophages on polyurethane >/= silicone > teflon > TCPS. These data show a correlation of (1) cytokines (TNFalpha, GM-CSF) and HSP70i, (2) NF-kappaB and HSP70i by monocytes/macrophages after contact with polymers. Thus, HSP70i might be a useful molecular candidate for exploring biomaterial-induced inflammatory reaction.

Effect of gamma-L-glutamyl-L-dopa on phosphate excretion.

gamma-L-glutamyl-L-DOPA (gludopa) is a dopamine prodrug that is relatively specific for the kidney. Because dopamine is phosphaturic, the present study compared the phosphaturic effects of the infusion of equimolar doses of gludopa (n = 8), L-DOPA (n = 8), and gamma-L-glutamyl-L-tyrosine (glutyrosine, n = 6). Glutyrosine was used as a control to evaluate the effect of the glutamyl portion of gludopa on phosphate excretion. Sprague-Dawley rats (350 to 400 g) were anesthetized with 5-sec-butylethyl-2-thyobarbituric acid (Inactin; 100 mg/kg, IP) and underwent thyroparathyroidectomy. Clearances were taken during the infusion of normal saline vehicle, followed by the infusion of gludopa, L-DOPA, or glutyrosine, all infused at the rate of 10 nmol/kg bolus and 0.8 nmol/kg/min (iv). To determine the contribution of glutamyl derivative to phosphate excretion, gludopa or L-DOPA was infused in the presence of SCH23390, a DA-1 receptor antagonist. Gludopa infusion significantly increased dopamine excretion (from 1.9+/-0.2 ng/min to 17.0+/-3.9 ng/min, delta15.0+/-3.9 ng/min, P < .008) and fractional excretion of phosphate (from 2.6%+/-0.6% to 34.8%+/-1.8%, delta32.0%+/-1.6%, P < .001). L-DOPA infusion significantly increased dopamine excretion (from 1.4+/- 0.4 ng/min to 9.7+/-1.6 ng/min, delta8.3+/-1.5 ng/min, P < .001) and fractional excretion of phosphate (from 1.7%+/-0.6% to 8.2%+/-2.0%, delta6.4%+/-1.5%, P < .004). Glutyrosine infusion significantly increased fractional excretion of phosphate (from 2.8%+/-0.8% to 17.5%+/-5.2%, delta14.6%+/-4.8%, P < .03) without changing dopamine excretion (delta0.5+/-0.2 ng/min). Infusion of gludopa in the presence of SCH23390 increased fractional excretion of phosphate (from 5.7%+/-2.5% to 12.6%+/-3.5%, delta6.8%+/-2.3%, n = 6, P < .03), whereas SCH23390 completely blocked the phosphaturic effect of L-DOPA. We conclude that gamma-L-glutamyl-L-DOPA is more phosphaturic than L-DOPA in the rat because of the combined effects of dopamine and the glutamyl moiety.

Dopamine enhances the phosphaturic effect of PTH during acute respiratory alkalosis.

The phosphaturic response to parathyroid hormone (PTH) is blunted during acute respiratory alkalosis. The objective of the present study was to determine the effect of dopamine on the blunted phosphaturic response to PTH during acute respiratory alkalosis. The phosphaturic response to PTH was determined in thyroparathyroidectomized (TPTX) normocapnic and respiratory alkalotic rats in the absence and presence of the infusion of exogenous dopamine (25 microg/kg/min) or of 3,4-dihydroxyphenylalanine (L-DOPA, 250 microg/kg/min) to increase endogenous dopamine synthesis. In normocapnic rats, PTH infusion (33 U/kg plus 1 U/kg/min) significantly increased the fractional excretion of phosphate (FE(Pi)), from 1.5%+/-0.5% to 28.4%+/-4.0%, (deltaFE(Pi) 26.9%+/-4.1%, n = 11, P<.05); in respiratory alkalotic rats, the increase was from 0.4%+/-0.1% to 11.4%+/-1.7% (deltaFE(Pi) 11.0%+/-1.8%, n = 13, P<.05). However, the phosphaturic response to PTH was attenuated in respiratory alkalotic rats (deltaFE(Pi) 26.9%+/-4.1% vs 11.0%+/-1.9%, P<.05). In normocapnic rats, in the presence of dopamine or L-DOPA infusions, PTH infusion significantly increased the FE(Pi) from 6.1%+/-2.3% to 33.4%+/-8.0% (deltaFE(Pi) 27.3%+/-7.0%, n = 5) and from 3.2%+/-0.6% to 32.5%+/-3.3% (deltaFE(Pi) 29.3%+/-3.2%, n = 7), respectively. In respiratory alkalotic rats, in the presence of dopamine infusion, PTH significantly increased the FE(Pi), from 0.6%+/-0.2% to 19.3%+/-3.3% (deltaFE(Pi) 18.7%+/-3.3%, n = 6); in the presence of L-DOPA infusion it increased from 1.0%+/-0.3% to 20.5%+/-2.8% (deltaFE(Pi) 19.5%+/-2.9%, n = 8, P<.05 as compared with PTH alone). Thus the phosphaturic effect of PTH that was attenuated in respiratory alkalotic rats was enhanced by stimulation of endogenous dopamine synthesis by the infusion of L-DOPA.

Chronic oral L-DOPA increases dopamine and decreases serotonin excretions.

Given the common pathways for uptake and synthesis for dopamine and serotonin, enhanced renal dopamine synthesis in response to increased substrate 3,4-dihydroxyphenylalanine (L-DOPA) is postulated to decrease renal serotonin synthesis. The present study compared the effects of chronic oral administration of L-DOPA on dopamine and serotonin excretion in vivo, with the effects of enhanced dopamine synthesis per nephron due to adaptation to reduced renal mass (RRM). Four groups of rats were studied: sham-operated rats and rats with RRM in the absence and presence of chronic oral L-DOPA. L-DOPA (2 mg. 100 g body wt(-1). day(-1)) for 6-14 days increased calculated dopamine synthesis per nephron in sham-operated rats from 2.0 +/- 0.3 (n = 7) to 13.6 +/- 1.8 pg. day(-1). nephron(-1) (n = 7, P < 0.05) and in rats with RRM from 6.1 +/- 1.3 (n = 7) to 39.3 +/- 5.2 pg. day(-1). nephron(-1) (n = 7, P < 0.05). Chronic oral L-DOPA concomitantly decreased serotonin synthesis per nephron in sham-operated rats (1.6 +/- 0.1 to 1.0 +/- 0.1 pg. day(-1). nephron(-1), n = 7, P < 0.05) and in rats with RRM (5.6 +/- 0.9 to 2.6 +/- 0.4 pg. day(-1). nephron(-1), n = 7, P < 0.05). Both serotonin and dopamine synthesis per nephron were increased in rats with RRM. In conclusion, chronic oral administration of L-DOPA enhances dopamine excretion and decreases serotonin excretion in normal rats and in rats with reduced renal mass. Both dopamine and serotonin excretions per nephron were elevated by renal mass reduction.

Remote laser generation of narrow-band surface waves through optical fibers.

This paper demonstrates the use of a fiberoptic bundle for flexible, compact, remote, and noncontact laser generation of surface ultrasonic waves in materials. The bundle is able to deliver Nd:YAG pulsed light with a 60% delivery efficiency up to an average energy of 55 mJ/pulse for a pulse duration on the order of 10 ns and a pulse repetition rate of 20 Hz without signs of fiber damage. Details of the bundle construction and surface preparation are given, and pulsed light delivery tests performed with single tapered fibers are discussed. The high-power light delivery capabilities of the bundle are demonstrated for the generation of narrow-band surface waves in a Carbon/PEEK composite laminate by a spatial modulation technique that employs a periodic transmission mask. Single laser pulse ultrasonic tonebursts are clearly detectable using a small aperture piezoelectric transducer while ensuring thermoelastic generation conditions. The theory of narrow-band generation of surface acoustic waves is improved by accounting for the strength nonuniformity of the illumination sources. In addition, the effect of the number of illumination sources on the bandwidth of the generated surface wave is assessed experimentally, and excellent agreement is shown with the theoretical results predicted by the improved model.

Effect of renal interstitial infusion of L-dopa on sodium and phosphate excretions.

It has been hypothesized that dopamine synthesized by the proximal tubule can act as a paracrine substance that regulates reabsorption by the proximal tubule. The present study was performed to study the effects of the stimulation of endogenous synthesis of dopamine by infusion of L-DOPA directly into the renal interstitium on sodium and phosphate excretions and to determine the roles of D1 and D2 receptors in the response. The infusion of L-DOPA (50 microg/kg/min) into the renal interstitium through an implanted matrix significantly increased the fractional excretion of sodium (FENa) from 1.0%+/-0.2% to 3.1%+/-0.6% and the fractional excretion of phosphate (FEPi) from 23%+/-3% to 36%+/-3%, P < .05, n = 10. The infusion of D1 receptor antagonist SCH23390 or SKF83566 (5 microg/kg/min) into the renal interstitium blocked the natriuretic (FENa 1.5%+/-0.2% to 1.9%+/-0.4%) and phosphaturic (FEPi 41%+/-3% to 41%+/-4%) effects of L-DOPA infusion. The infusion of the D2 receptor antagonist sulpiride at a rate of 4 microg/kg/min into the renal interstitium also attenuated the natriuretic (FENa 1.3%+/-0.3% to 1.6%+/-0.5%) and phosphaturic effects of L-DOPA infusion (FEPi 36%+/-5% to 39%+/-5%). We conclude that the renal interstitial infusion of L-DOPA increases sodium and phosphate excretions and that these responses are mediated by D1 and D2 receptors.

Effect of renal interstitial adenosine infusion on phosphate excretion in diabetes mellitus rats.

We previously demonstrated an increased sensitivity of the renal vasculature to adenosine (ADO) mediated via ADO A1 receptors in streptozotocin (STZ) diabetic rats. Because ADO stimulates P(i) reabsorption in the proximal tubule, the present study was performed to determine whether the sensitivity of the renal tubular system to the antiphosphaturic effect of ADO is enhanced in STZ rats. Clearance studies were performed, and ADO was infused into the renal interstitium via implanted matrices in STZ- and control (Con) rats to mimic the effects of endogenous ADO. Renal phosphate excretion was significantly increased in STZ rats (0.75 +/- 0.05 mumol/24 h) compared with Con rats (0.35 +/- 0.08 mumol/24 h), and fractional phosphate excretion (FEPi) tended to be higher in STZ rats (34.8 +/- 4.1%) than in Con rats (26.7 +/- 2.2%). Renal interstitial ADO infusion (5 mumol/h) was significantly more antiphosphaturic in STZ rats (FEPi decreased by 2.90 +/- 1.6%; P > 0.05), in which ADO only tended to decrease FEPi. To determine the role of ADO A1 receptors on P(i) excretion, the selective ADO A1 receptor blocker 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) was infused into the renal interstitium. DPCPX increased FEPi by 4.3 +/- 1.2% (P < 0.05) in the presence and 7.1 +/- 3.9% (P < 0.05) in the absence of ADO infusion in Con rats but had no effect on FEPi in STZ rats. In conclusion, STZ-diabetes mellitus enhances the antiphosphaturic effect of ADO by mechanisms unrelated to ADO A1 receptor stimulation.