Renal artery perfusion modifies ischemia/reperfusion injury

Static and dynamic contact angles of water droplet on a solid surface using molecular dynamics simulation

The present study investigates the variation of static contact angle of a water droplet in equilibrium with a solid surface in the absence of a body force and the dynamic contact angles of water droplet moving on a solid surface for different characteristic energies using the molecular dynamics simulation. With increasing characteristic energy, the static contact angle in equilibrium with a solid surface in the absence of a body force decreases because the hydrophobic surface changes its characteristics to the hydrophilic surface. In order to consider the effect of moving water droplet on the dynamic contact angles, we apply the constant acceleration to an individual oxygen and hydrogen atom. In the presence of a body force, the water droplet changes its shape with larger advancing contact angle than the receding angle. The dynamic contact angles are compared with the static contact angle in order to see the effect of the presence of a body force.

Pneumatic Lithotripsy through Pyelotomy Incision during Open Surgery for Staghorn Calculi

INTRODUCTION

Our purpose was to remove large-volume staghorn calculi with less morbidity and maximum ease without an anatrophic nephrolithotomy, with the use of a pneumatic lithotriptor during pyelolithotomy to disintegrate the branches of stones extending into the calyces and retained calyceal fragments.

PATIENTS AND METHODS

Sixteen patients (17 renal units) with large-volume staghorn stones were evaluated with blood urea nitrogen (BUN), creatinine levels, urinalysis, and culture, excretory urography (IVP), and 99mtechnetium dimercaptosuccinic acid (DMSA) renal scintigraphy preoperatively. Patients were treated with a pneumatic lithotriptor at the time of open pyelolithotomy. Bilateral surgery was performed in 1 patient. The mean follow-up period was 12 (range 6-24) months. The patients were re-evaluated postoperatively at 6 months with BUN and serum creatinine measurements, urinalysis and culture, IVP, and renal scintigraphy with DMSA. Data were analyzed by one-way ANOVA test. p < 0.05 was considered statistically significant.

RESULTS

After treatment, 15 of 17 renal units (88%) were rendered stone-free while residual fragments remained in two patients. Average operation time was 190 min (range 135-285) with a mean blood loss of 226 ml (range 140-425). No patient required blood transfusion. Average length of hospital stay was 4.2 days (range 3-7). Six months after surgery, mean BUN and creatinine levels were decreased from 31.2 to 28.2 mg/dl (p = 0.248) and from 1.3 to 1.1 mg/dl (p = 0.001), respectively. Renal scintigraphy with DMSA revealed an increase in ipsilateral average renal function from 39 to 43% (p = 0.043). IVP also revealed a decrease in pelvicalyceal dilatation in almost all patients with a well-functioning kidney and without any stone recurrence. No complications were encountered postoperatively except for an episode of high fever in 1 patient.

CONCLUSION

Avoiding incision of the renal parenchyma and arterial clamping, without significant bleeding and the nephron loss seem to be the advantages of this technique. Kidney function can be preserved with this simple and easily applicable method, which may be an alternative procedure to anatrophic nephrolithotomy for the majority of patients with staghorn calculi requiring open surgery.

A reproducible model of circulatory arrest and remote resuscitation in rats for NMR investigation

BACKGROUND AND PURPOSE

Because noninvasive physiological monitoring of cerebral blood flow, metabolic integrity, and brain ion and water homeostasis can now be accomplished with new, state-of-the-art MR spectroscopy and imaging techniques, it is appropriate to develop controllable and reproducible animal models that permit prolonged circulatory arrest and resuscitation in the magnet and also allow for studies of long-term survival and outcome. We have developed such a model in rats that involves minimal surgical preparations and can achieve resuscitation remotely within precisely controlled time.

METHODS

Cardiac arrest was induced by asphyxiation, the duration of which ranged from 8 to 24 minutes. Resuscitation was achieved remotely by a slow, intra-aortic infusion of oxygenated blood (withdrawn either from the same rat before asphyxia or from a healthy donor rat) along with a resuscitation cocktail containing heparin (50 U/100 g), sodium bicarbonate (0.1 mEq/100 g), and epinephrine (4 micrograms/100 g). The body temperature was measured by a tympanic thermocouple probe and was controlled either by a heating pad (constant tympanic temperature = 37 degrees C) or by warm ambient air (constant air temperature = 37 degrees C). Interleaved 31P/1H nuclear magnetic resonance (NMR) spectroscopy was used in a selected group of rats to measure the cerebral metabolism before and during approximately 20 minutes of circulatory arrest and after resuscitation.

RESULTS

The overall success rate of resuscitation, irrespective of the duration of cardiac arrest, was 82% (51 of 62). With a programmed infusion pump, the success rate was even higher (95%). The survival time for rats subjected to 15 and 19 minutes of asphyxia with core temperature tightly controlled was significantly lower than that with ambient temperature control (P < 0.001 and P < 0.04, respectively). High-quality NMR spectra can be obtained continuously without interference from the resuscitation effort. Final histological examinations taken 5 days after resuscitation showed typical neuronal damages, similar to those found in other global ischemia models.

CONCLUSIONS

Because the no-flow time and resuscitation time can be precisely controlled, this outcome model is ideally suited for studies of ischemic and reperfusion injuries in the brain and possibly in other critical organs, permitting continuous assessment of long-term recovery and follow-up in the same animals.