Neuronal current imaging: An experimental method to investigate electrical currents in dogs with idiopathic epilepsy.

BACKGROUND: The diagnosis of idiopathic epilepsy (IE) in dogs is based on exclusion of other potential causes of seizures. Recently, a novel magnetic resonance imaging (MRI) sequence that utilizes a variant of the rotary saturation approach has been suggested to detect weak transient magnetic field oscillations generated by neuronal currents in humans with epilepsy. HYPOTHESIS/OBJECTIVES: Effects on the magnetic field evoked by intrinsic epileptic activity can be detected by MRI in the canine brain. As proof-of-concept, the novel MRI sequence to detect neuronal currents was applied in dogs. ANIMALS: Twelve dogs with IE and 5 control dogs without a history of epileptic seizures were examined. METHODS: Prospective case-control study as proof-of-concept. All dogs underwent a clinical neurological examination, scalp electroencephalography, cerebrospinal fluid analysis, and MRI. The MRI examination included a spin-locking (SL) experiment applying a low-power on-resonance radiofrequency pulse in a predefined frequency domain in the range of oscillations generated by the epileptogenic tissue. RESULTS: In 11 of 12 dogs with IE, rotary saturation effects were detected by the MRI sequence. Four of 5 control dogs did not show rotary saturation effects. One control dog with a diagnosis of neuronal ceroid lipofuscinosis had SL-related effects, but did not have epileptic seizures clinically. CONCLUSIONS AND CLINICAL IMPORTANCE: The proposed MRI method detected neuronal currents in dogs with epileptic seizures and represents a potential new line of research to investigate neuronal currents possibly related to IE in dogs.

Impact of pond aquaculture effluents on seagrass performance in NE Hainan, tropical China.

The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ(15)N in seagrass leaves and epiphytes (6-9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ(34)S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.

Natural and human influences on nutrient transport through a small subtropical Chinese estuary.

Global understanding of land-ocean nutrient fluxes increasingly recognizes the disproportionate importance of small rivers. We studied nutrient fluxes from a small catchment in fast developing southern China to uncover effects of land-use. Water was sampled in the macro-tidal estuary of Nanliu River and adjacent Lianzhou Bay in spring and summer of investigate spatial and temporal variations of dissolved nutrients. High riverine concentrations of nitrate (NO3; up to 220 µM) and phosphate (PO4; up to 3.7 µM) mainly originated from agricultural fertilizer input. Riverine dissolved silica (Si; up to 47 µM) increased in the oligosaline part of the estuary through human disturbance of bottom sediments. Dissolved organic nitrogen (DON; up to 194 µM) and ammonium (NH4; up to 40 µM) concentrations increased within the estuary due to inputs from livestock and mussel beds, respectively. Aquaculture ponds contained high concentrations of NH4 (up to 355 µM) and DON (up to 151 µM) but are not an important source to the estuary due to rare wastewater discharge and low absolute nutrient amounts relative to river export. Nutrient concentrations in Lianzhou Bay were low because tidal currents disperse land-derived nutrients offshore into the adjacent Beibu Gulf. A high proportion of regenerated nitrogen in the bay suggests that primary production is sustained by rapid in situ nutrient cycling between primary producers and benthic consumers. High nutrient export makes the Nanliu River an important nutrient source for the north-western South China Sea, despite its proportionately small size. Macro-tide induced short-term concentration changes exceed variability on seasonal and sub-seasonal scales. All nutrients vary inter-annually and between seasons, depending on precipitation-driven river runoff. Total nutrient export to Beibu Gulf coastal waters is stronger during the high discharge period in summer and autumn. In recent years changing nitrogen to phosphorus ratios have alleviated phosphorus limitation in Lianzhou Bay, permitting increased primary productivity.

Periarterial papaverine improves early postoperative renal function after retroperitoneoscopic partial nephrectomy.

OBJECTIVE: To study the impact of periarterial papaverine application on the postoperative glomerular filtration rate (GFR) after retroperitoneoscopic partial nephrectomy (PN). MATERIALS AND METHODS: A consecutive series of patients underwent retroperitoneoscopic PN with intraoperative, periarterial application of 50 mg of papaverine. These patients were compared with a group of patients who underwent retroperitoneoscopic PN at this institution prior to this protocol. Patients were matched for preoperative GFR, tumor size, ischemia time, and operative time. RESULTS: In total, 37 patients who received periarterial papaverine (P) and 37 patients without periarterial papaverine, who served as controls (C), were included in this analysis and matched according to preoperative GFR (P: 98.2, C: 97.8 ml/min/1.72 m(2)), tumor size (P: 2.5 cm, C: 2.5 cm), ischemia time (P: 22 min, C: 23 min), and operative time (P: 86 min, C: 85 min). Postoperative GFR was 86.4 ml/min/1.72 m(2) in controls (C) and 91.8 ml/min/1.72 m(2) in the papaverine group. The pre- to postoperative decrease in GFR was reduced by 56.9% in the papaverine group compared with controls (relative decrease in GFR: P: 5.3% vs. C: 12.5%; P = 0.02). Intra- and postoperative complications were pneumothorax (P: n = 2, C: n = 3), urinary fistula (P: n = 0, C: n = 2), and one suture-fixed drainage (P: n = 1, C: n = 0). No papaverine-related side effects were observed, and the surgical procedure was not hampered by the periarterial application of papaverine. CONCLUSION: As with laparoscopic donor nephrectomy, periarterial papaverine seems to improve postoperative renal function after retroperitoneoscopic partial nephrectomy. This nephroprotective effect might be particularly advantageous for patients with an impaired renal function preoperatively.