Robert W. Hopkins

Levels of allantoin and uric acid in dogs subjected to hemorrhagic shock

Abstract The changes in concentration of uric acid and of allantoin were studied in the blood and lymph of mongrel dogs in experimental hemorrhagic shock under sodium pentobarbital anesthesia. The object of the experiment was to determine whether the rise in uric acid concentration in experimental shock results from increased breakdown of adenosine and guanosine nucleotides or from failure of the hepatic conversion of uric acid to allantoin. The concentration of uric acid in serum and lymph was significantly higher in the dogs that were bled than in those serving as controls (Fig. 2). The rate of conversion of uric acid to allantoin during oligemia did not change significantly in these dogs (Fig. 3). After the return of reservoir blood to the animals, the concentration of allantoin in serum and lymph was significantly higher in these dogs than in the control animals that had not been bled (Fig. 3). The increase in the concentration of uric acid in serum and lymph thus results from an increased degradation of the adenosine and guanosine nucleotides, and not from failure of conversion of uric acid to allantoin in the liver.

A sensitive assay for allantoin

Abstract Allantoin is separated by thin-layer chromatography (TLC) and sprayed with an acidic solution ofp-dimethylaminobenzaldehyde. The yellow color produced is read in a densitometer and compared with that of a standard. The lower limit of quantitation is 0.1 μg per spot (0.5 mg/100 ml). The method can be utilized for the estimation of allantoin in serum, lymph, and urine.

Long-term amiodarone administration protects against global myocardial ischemia

Reports on the effects of amiodarone on cardiac function have been variable. This study addresses the effect of long-term amiodarone administration on recovery of cardiac function after a period of global ischemia. Normotensive and spontaneously hypertensive rats were used. Normotensive rats (n = 6) received 240 mg/kg amiodarone for 4 weeks, for a total of 72 +/- 3 mg. Hypertensive rats (n = 6) received 500 mg/kg amiodarone for 4 weeks, for a total of 116 +/- 5 mg. Final myocardial concentrations of amiodarone and desethylamiodarone were 1.85 +/- 1.75 and 0.50 +/- 0.61 micrograms/g wet weight for the normotensive rats and 1.30 +/- 0.58 and 0.31 +/- 0.17 micrograms/g for the hypertensive rats (p = nonsignificant). Equal numbers of controls received sterile saline solution for 4 weeks. The hearts were excised and perfused in a Langendorff apparatus. The results indicate that, after 15 minutes of normothermic ischemia, hearts treated with this relatively low dose of amiodarone recovered a greater percentage of preischemic work (97% +/- 13%) as compared with the controls (76% +/- 17%) (p less than 0.005).

The Use of Segmental Femoropopliteal Duplex Scanning for Initial Vascular Laboratory Testing of Patients with Peripheral Arterial Disease

Introduction —Segmental femoropopliteal duplex scanning in conjunction with ankle plethysmographic waveforms and ankle/brachial indices (ABI) was evaluated as an alternative to traditional physiologic testing for the initial vascular laboratory evaluation of patients with lower extremity peripheral arterial disease (PAD). To assess the potential of this evaluation, patients with PAD were evaluated in the vascular laboratory with (1) pulse volume recording and segmental pressures (SPVR) and (2) femoropopliteal duplex imaging with pulsed Doppler waveform analysis and bilateral ankle plethysmographic waveforms and ABI (SDuplex). Methods. —SPVR and SDuplex data were prospectively obtained from 39 patients and 72 limbs. Separate technologists performed the physiologic and duplex examinations independently. Angiograms performed within 90 days were used as the gold standard for evaluating results from both procedures. Results from both examinations were interpreted for severe (>50% diameter reduction) inflow and superior femoral artery (SFA) disease. A McNemar test was performed on the SPVR and SDuplex paired data, and direct (hands-on) examination time was calculated for both procedures. Results. —Angiograms were available for 20 of 72 (28%) of the limbs evaluated and demonstrated no significant differences between both methods for evaluating inflow (femoral or above) disease, yet SDuplex was superior to SPVR for evaluating SFA disease. McNemar test data also suggested that SDuplex was superior to SPVR in diagnosing severe disease at the SFA level. The average time for SPVR examination performance was 28 minutes and 31 minutes for SDuplex with ABI and ankle waveforms. Conclusions. —SDuplex was superior to SPVR for evaluating SFA disease. No noteworthy differences in direct (hands-on) examination times for both procedures suggest the additional benefit of enhanced reimbursement. With superior SFA accuracy, more site-specific information, and greater reimbursement potential, SDuplex should be considered an alternative to the traditional physiologic examination for evaluating patients with lower extremity PAD.