Perioperative vascular flushing perfusion in acute mesenteric artery occlusion

AIM

To evaluate in animals and patients a perioperative vascular flushing perfusion with antioxidants in order to improve postischaemic condition of the bowel and hence, to prolong the warm ischaemia tolerance time.

MATERIALS

40 rats and 10 patients with acute mesenteric artery occlusion.

METHODS

Intestinal ischaemia was induced in 40 rats by clipping the superior mesenteric artery for 1 h. Thirty animals received a vascular flushing perfusion with oxygen radical scavengers (ascorbate, tocopherol or oxypurinol). Histology, ATP, ADP levels were examined in tissue biopsies and malondialdehyde, lactate dehydrogenase, alkaline phosphatase levels were measured in blood during ischaemia and 60 min after reperfusion.

RESULTS

ATP restoration was particularly improved in the oxypurinol group (ATP/ADP-ratio = 2 vs. 1.2 in the control group). Malondialdehyde increase observed after reperfusion as a marker of radical induced lipid destruction was significantly attenuated (control group 160% of base level vs. 127% in the ascorbate group, 133% in the tocopherol group, 121% in the oxypurinol group). Histological alterations during ischaemia/reperfusion were markedly less extensive in the perfusion groups than in control. The patients treated perioperatively with arterial flushing perfusion had an overall mortality of 10%.

CONCLUSION

Vascular flushing perfusion with oxygen radical scavengers prevents radical induced ischaemic damage and may prolong the warm ischaemic tolerance time of the intestine.

Efficacy and proarrhythmia of oral sotalol in pediatric patients

OBJECTIVES

This study sought to assess the efficacy of oral sotalol for various arrhythmias in pediatric patients and to evaluate the incidence of proarrhythmia and systemic side effects.

BACKGROUND

Sotalol is a beta-adrenergic blocking agent with additional class III antiarrhythmic properties. Experience in pediatric patients is limited. Data concerning the incidence of proarrhythmia in children are lacking.

METHODS

Seventy-one pediatric patients (mean age 7.3 years) with various supraventricular and ventricular tachyarrhythmias were treated with oral sotalol. All the patients were admitted to the hospital for initiation of sotalol therapy. Antiarrhythmic and proarrhythmic effects of sotalol were assessed by daily surface electrocardiograms (ECGs) during the in-hospital phase and by serial Holter monitoring.

RESULTS

Sotalol was either completely (27 [66%] of 41 patients) or partially effective (11 [27%] of 41) in 38 (93%) of 41 patients with supraventricular reentrant tachycardias. In patients with atrial flutter predominantly after operation for congenital heart disease, sotalol was effective in 84% of patients (completely in 9 of 19 and partially in 7 of 19). Ventricular tachycardia was completely (3 of 11) or partially (4 of 11) controlled in 64% of children. Proarrhythmia occurred in seven patients (10%) and consisted of symptomatic bradycardia from sinoatrial block and high grade atrioventricular (AV) block, respectively, in two children; asymptomatic high grade AV block in one; torsade de pointes in one; and relevant increased ventricular ectopic activity in three. Proarrhythmia required drug discontinuation in four patients. Mean duration of treatment for all patients was 18 months (range 1 to 40).

CONCLUSIONS

Sotalol was an effective antiarrhythmic drug for a wide range of pediatric tachyarrhythmias. The considerable number of patients with proarrhythmic effects indicates the need for initiation of treatment on an inpatient basis and close monitoring by serial Holter electrocardiography.

[Results of oral sotalol therapy in children with supraventricular and ventricular arrhythmias]

Experience with oral sotalol, a beta-blocker with class III-antiarrhythmic properties, is limited in the pediatric population. Sotalol was administered to 32 patients with a mean age of 8.7 years (range 1 day-19.9 years). Mean dosage was 4.6 (1.5-9.4) mg/kg or 122.1 (52-306) mg/m2, respectively. In 27/32 patients, at least 1 antiarrhythmic agent had failed to control the dysrhythmia before sotalol was started. Cardiac diagnoses included normal heart (n = 16), status after correction of congenital heart disease (n = 13), and cardiomyopathy (n = 3). Success (based on symptoms and 24-h electrocardiogram) was achieved in 16/18 patients with reentry supraventricular tachycardia, in 7/8 patients with atrial flutter, and in 4/6 patients with ventricular tachycardia. During a mean follow-up of 15.6 (2-78) months, proarrhythmia occurred in five (16%) patients (symptomatic bradycardia n = 2, QT-prolongation and ventricular extrasystoles n = 1, ventricular extrasystoles n = 1, 2 degrees av-block n = 1), requiring dosage reduction (n = 3), cessation of treatment (n = 1) and pacemaker implantation in one patient, respectively. Symptomatic hypotension was noted in two patients, in whom therapy had to be stopped. Sotalol was a very effective agent for the treatment of various pediatric cardiac dysrhythmias. However, incidence of proarrhythmic effects warrants close electrocardiographic monitoring.

Electrocardiogram acquisition during MR examinations for patient monitoring and sequence triggering

We have developed a method for measuring the electrocardiogram (ECG) continuously during MR examinations. In contrast to ECG acquisition by wires, our new method is to amplify and convert the ECG into an optical signal directly above the patient's heart. The optical signal is transmitted out of the magnet bore by optical fiber. The small and fixed dimensions of the ECG amplifier avoid interactions with the MR system because of shorter electrical structures and smaller enclosed areas. Tests of the proposed device in a 1.5 Tesla MR system show that continuous and reliable ECG monitoring and sequence triggering are possible.

Transesophageal echocardiography for prosthetic valve evaluation: is it always necessary?

Transesophageal echocardiography provides excellent images of mitral and aortic prostheses, due to its higher resolution and less interference from other cardiac structures. Since the introduction of transesophageal echocardiography, it has proved to be valuable for the evaluation of prosthetic heart valves. "Classic" indications include the evaluation of prosthetic valve endocarditis, the search for paravalvular abscesses, and the assessment of regurgitation in mechanical, especially mitral, prostheses. New technical developments such as biplane or multiplane transducers enhance the diagnostic capabilities of the technique. Transesophageal echocardiography can also have advantages in recognizing obstructive lesions such as thrombi or pannus, and help understand the complex morphology of prostheses in grafts. Transesophageal echocardiography should be considered a backup technique whenever transthoracic echocardiography, which always remains the primary approach, is inconclusive or negative in the presence of clinically suspected prosthetic valve malfunction.

Superoxide dismutase promotes ATP and GTP restoration of rat small intestine during postischaemic reperfusion

The small intestine of rats was prepared according to a procedure which is taken for preservation and transplantation in clinical practice. The blood supply of the rat intestine was completely interrupted for 30 min in situ. During this period the lumen of the intestine was rinsed with Ringer-lactate solution. This ischaemic period was followed by 10 min of reperfusion. As a result a decrease in ATP, and GTP concentrations, and of the total adenine nucleotide content during the preservation period occurred. In animals pretreated with superoxide dismutase (i.v. application; superoxide dismutase preparation from human erythrocytes) an accelerated restoration of nucleotide concentrations during the reperfusion period was observed. From the beneficial effect of superoxide dismutase it can be concluded, that there is a considerable formation of active species of oxygen which disturb the energy generation by the mitochondrial respiratory chain during ischaemia/re-oxygenation.

Comparative inhibition of hepatitis B virus DNA polymerase and cellular DNA polymerases by triphosphates of sugar-modified 5-methyldeoxycytidines and of other nucleoside analogs

Of a series of 14 nucleoside 5'-triphosphates, those of 2',3'-dideoxy-3'-fluoro-5-methylcytidine, 3'-azido-2',3'-dideoxy-5-methylcytidine, 2',3'-dideoxy-3'-fluoroguanosine, 2',3'-didehydro-2',3'-dideoxy-5-methylcytidine, 2',3'-dideoxy-3'-fluoro-5-ethylcytidine, and 2',3'-dideoxy-3'-fluoroadenosine emerged as the most potent inhibitors of hepatitis B virus DNA polymerase (50% inhibitory dose, 0.03 to 0.35 microM). In contrast, cellular DNA polymerases proved to be resistant to (alpha) or partially affected by (beta) these analogs. These compounds are among the most effective and selective inhibitors of endogenous hepatitis B virus DNA polymerase recognized to date.

Sensibility and cutaneous reinnervation after breast reconstruction with musculocutaneous flaps

Sensibility and sensory reinnervation were investigated in 19 patients who underwent, after mastectomy, a breast reconstruction using myocutaneous flaps. A comparative study in reinnervation of the flaps has been performed either after surgery with a latissimus dorsi flap with prosthesis or after surgery with a simple or double pedicle transverse rectus abdominal flap. Ten patients with latissimus dorsi flaps and 9 patients with transverse rectus abdominal flaps were tested. The tests included stimulation with touch, pressure, pin prick, and temperature. The patients were also interviewed regarding their impressions, a subjective sensibility. These results show that the recovery of sensibility by patients who underwent surgery with the transverse rectus abdominal flap technique is superior, objectively and subjectively.

Ion transport in epithelial cells from the bovine trachea in culture: effects of dexamethasone and aldosterone

The ion transport properties of epithelial cells from the bovine trachea grown in culture were investigated. The cellular uptake of 22Na+, 36Cl- and 86Rb+ was measured and the sensitivity of ion uptake to amiloride and bumetanide revealed the presence of the transport pathways that exist in the native tissue. The action of corticosteroids, dexamethasone and aldosterone (0.1 or 1.0 microM), was studied by measuring the short-circuit current and the uptake of Na+ and Cl- following a treatment of 18 h, 2 or 8 days. The results showed that, in each situation, dexamethasone enhanced markedly the amiloride-sensitive current and Na+ uptake. In contrast, aldosterone exerted no detectable effect on the ion transport and electrical properties.

Inhibition of HIV-replication by 3'-fluoro-modified nucleosides with low cytotoxicity

From a series of newly synthesized 3'-fluoro-modified nucleosides the C-5-chloro-substituted derivative of 2',3'-dideoxy-3'-fluorouridine (FddUrd) and the 4-thio analogue of 2',3'-dideoxy-3'-fluorothymidine (FddUrd) emerged as the most efficient and selective anti-HIV agents. Their antiviral doses (ED50) proved to be 700-and 480-fold below their toxic doses (CD50) in MT-4 cells. The 50% inhibitory dose of cell proliferation of the 5-chloro-substituted FddUrd and its parent agent FddUrd was found to be in the millimolar range for various other human cell-lines and for mouse CFU-GM. The 5'-triphosphate of FddUrd as well as of its 5-Chloro derivative are demonstrated to be two of the most active and selective inhibitors of the HIV-reverse transcriptase (IC50 = 0.07 +/- 0.01 and 0.04 +/- 0.006 microM).

Solid-phase synthesis of oligoribonucleotides using 9-fluorenylmethoxycarbonyl (Fmoc) for 5'-hydroxyl protection

Efficient solid-phase synthesis of a series of oligoribonucleotides of up to 20 residues is described that utilises the 9-fluorenylmethoxycarbonyl group (Fmoc) for 5'-protection and 4-methoxytetrahydropyran-4-yl (Mthp) for 2'-protection of ribonucleotide monomers and a phosphoramidite coupling procedure. The Fmoc group is removed after each coupling step by treatment with 0.1M DBU in acetonitrile. Oligoribonucleotides are isolated in 2'-protected form in good yield and shown to be readily and efficiently deprotected by mild acidic treatment.

Diphenylamine-2-carboxylate stimulates sodium ion transport in frog skin epithelium

1. Diphenylamine-2-carboxylate (DPC), added to the mucosal side of the frog skin, increased reversibly the short-circuit current (I0), even in SO2-(4) Ringer. Amiloride blocked this effect. 2. The maximal stimulation was 140% of the control value and the EC50 was 0.26 mM DPC. 3. The stimulatory effect of DPC was additive to that of oxytocin. 4. The dose-response curves for amiloride determined in the absence and in the presence of 1 mM DPC showed an IC50 of 1.0 microM and 0.8 microM amiloride, respectively. 5. Thus DPC, a blocker of Cl- channels in various Cl-transporting epithelia, exerts a stimulatory effect on the amiloride-sensitive Na+ transport in frog skin.

Phosphorylation, anti-HIV activity and cytotoxicity of 3'-fluorothymidine

3'-fluorothymidine (FddThd) is well phosphorylated to the 5'-triphosphate in various relevant cell-lines. This results in fairly stable levels of this compound without accumulation of the 5'-monophosphate to the extent described for 3'-azidothymidine (AzT). The di- and triphosphate of FddThd seems unable to influence the ribonucleotide reductase in permeable cells. FddThd protects 50% of the MT-4 cells against the cytopathic effect of HIV at 3 nM, but reduces the number of uninfected viable cells to 50% at 1.1 microM. All other tested human cell-lines displayed a far less antiproliferative sensitivity to FddThd, comparable with that of AzT.

[Warming resuspended erythrocyte concentrates with a new microwave device. In vitro results and clinical experiences in comparison with continuous flow warming]

Rapid warming of stored red cell concentrates demands a technique that provides careful treatment of the erythrocytes, reliability, simple handling, and prompt processing. The Fenwal BW-5, a dry-heat blood warmer, is a well-established blood heating device. However, its use is time-consuming and rather complicated. The newly developed Infusotherm 407 is a microwave blood warmer providing short prewarming time and easy handling, but its safe applicability for resuspended red cells had not previously been proven. MATERIALS AND METHODS. Using the disposable plastic Ery-Set Schiwa (100 ml NaCl 0.9%), 211 red cell concentrates were diluted; 115 were warmed by the Infusotherm 407 and 96 by the Fenwal BW-5. The age of the blood units ranged between 1 and 30 days and the volume between 300 and 350 ml after resuspension. The Infusotherm 407 produces pulsed high-frequency waves that are absorbed by the blood unit and transformed into heat. The swivelling mechanism of the rotating holder allows continuous mixing and uniform warming of the red-cell suspension. The blood temperature is registered on the bag's surface by a thermometer integrated in the rotating holder. At 32 degrees C, the warming process is stopped automatically. Within the Fenwal BW-5 a special plastic bag has to be fixed between two electrically heated thermostat-controlled plates. The bag contains the blood that is passing through in several coils. A constant working temperature is maintained by an electronic monitor system up to a blood flow of 150 ml/min. Several laboratory parameters, i.e. extracellular hemoglobin, potassium, lactate dehydrogenase, as well as mean erythrocyte volume (MCV) and osmotic fragility of the red cells were determined from samples prior to and after blood warming. Thus, apparent hemolysis, morphological changes, or discrete damage to the erythrocytes could be detected. RESULTS. We observed a slight elevation in hemolysis parameters after warming with both devices. The alterations were within the range for stored packed red cells given by the European Public Health Committee. MCV and osmotic fragility remained unchanged. We did not find any comparable data concerning diluted packed red cells for either of the devices. Our own results did not show any significant difference between the two methods of heating. DISCUSSION. From the literature, it is known that the erythrocytes of full-sized blood units with normal hematocrit are not damaged by microwave warming. In contrast, small blood units and undiluted packed red cells revealed considerable hemolysis and distinct changes in MCV and osmotic fragility.(ABSTRACT TRUNCATED AT 400 WORDS)

Test-ordering by multiple physicians increases unnecessary laboratory examinations

In modern teaching hospitals, patients typically receive direct care from a succession of different physicians, each of whom may order diagnostic tests on the same patient. We examined the association of test-ordering by multiple physicians with unnecessary duplication of 20-test chemistry profiles in 198 consecutively admitted patients. In a multivariate regression model, the number of duplicate chemistry profiles ordered for a patient was significantly correlated with the number of physicians ordering profiles after controlling for the overall intensity of profile testing. In a case-control analysis comparing duplicate with nonduplicate profiles, redundant tests were significantly more likely to have been ordered by a new physician who had not ordered a patient's previous profile than by the same physician who had ordered the previous chemistry panel. We conclude that test ordering by multiple physicians, the prevalent pattern in almost all teaching hospitals, predisposes to unnecessary laboratory examinations.