Partial reversal of the effects of extradural clonidine by oral yohimbine in postoperative patients

Extradural clonidine produces analgesia, with sedation, hypotension and bradycardia, in postoperative patients. This study assessed if oral yohimbine would reverse these side effects. We studied 30 ASA I-II patients undergoing orthopaedic surgery. After operation they were allocated randomly to three groups to receive placebo, extradural clonidine 450 micrograms or extradural clonidine 450 micrograms plus oral yohimbine 16 mg. Pain score was measured on a visual analogue scale (VAS); sedation was assessed on a simple scale graded from 0 (awake and alert) to 3 (deeply sedated, awakening after tactile stimulations) and heart rate and arterial pressure were monitored for 5 h. Yohimbine reversed the sedation induced by extradural clonidine, but also shortened the duration of analgesia (31 (SD 15) min, 186 (72) min and 126 (52) min in the placebo, extradural clonidine and extradural clonidine+yohimbine groups, respectively) (P < 0.05), and did not reduce the hypotension and bradycardia related to clonidine administration. These results suggest that alpha 2 adrenoceptors are mediators of the sedation induced by clonidine and that the haemodynamic effects are not related to stimulation of supraspinal alpha 2 receptors.

Epidural clonidine decreases postoperative requirements for epidural fentanyl

OBJECTIVE

This study assesses the possibility that clonidine may decrease analgesic opioid demand in postoperative patients.

METHODS

Twenty-five patients were allocated randomly after abdominal surgery to receive either an epidural bolus dose of fentanyl (1.0 mcg.kg-1) followed by a 1.0 mcg.kg-1h-1 continuous epidural infusion, or an epidural bolus dose of fentanyl (1.0 mcg.kg-1) followed by a continuous epidural infusion combining fentanyl 0.5 mcg.kg-1 x h-1 and clonidine 0.3 mcg.kg-1 x h-1. Pain was assessed at definite intervals on a visual analog scale (VAS) over 3 postoperative days. Epidural infusion was halved when VAS score was lower than 2. Patients were monitored with a pulse oximeter over 12 hours during the first postoperative night. Plasma fentanyl was measured by radioimmunoassay when patients left the recovery room and at 8 a.m. on the first and the second postoperative days.

RESULTS

VAS scores were comparable in the two groups of patients. The amount of fentanyl delivered was significantly lower in the fentanyl + clonidine group, as were the plasma fentanyl concentrations. The duration of SaO2 < 90% episodes was significantly less prolonged in the fentanyl + clonidine group (3.5 +/- 4.8 minutes versus 14.4 +/- 14.6 minutes).

CONCLUSIONS

The combination of clonidine to epidural fentanyl allows a decrease in opioid requirements without impairing analgesia. Reduction of opioids administration may have beneficial effects on respiratory function in postoperative patients.

Radiosensitive Chinese hamster irs2 cells show enhanced chromosomal sensitivity to ionizing radiation and restriction endonuclease induced blunt-ended double-strand breaks

The Chinese hamster irs2 cell line shows cellular hypersensitivity to ionizing radiation although the induction and repair of double-strand breaks (dsb) in bulk DNA is normal. Here we report that irs2 shows chromosomal hypersensitivity to ionizing radiation and the restriction endonuclease PvuII. The ratio of induced chromosomal aberrations in irs2 versus V79 was similar to that for survival (factor of between 2 and 4). PvuII was administered during cell poration with the bacterial toxin streptolysin O. We also report that when streptolysin O porated irs2 and V79 cells were treated with PvuII, and dsb assayed by neutral filter elution, equivalent numbers of dsb were induced in the two lines as a function of time following treatment. Our data show that irs2 has a DNA damage processing defect that leads to enhanced conversion of blunt-ended dsb into visible chromosomal damage.

Prolonged placement of spinal catheters does not prevent postdural puncture headache

OBJECTIVE

To determine whether leaving an intrathecal catheter in place in the postoperative period prevents postdural puncture headache (PDPH).

METHODS

Lumbar puncture was performed with an 18-gauge Tuohy needle. 0.5% bupivacaine spinal anesthesia was given through a 20-gauge catheter in 87 patients having orthopedic surgery. Postoperatively, patients were allocated randomly to have the catheter immediately withdrawn (group 1, N = 47) or kept in place for 12 to 24 hours (group 2, N = 40). Patients were questioned by a blinded observer, about PDPH twice a day on postoperative days 1, 2, 3, and 8.

RESULTS

The incidence of PDPH was 9.2%, and this was comparable in the two groups (5 patients in group 1 and 3 patients in group 2).

CONCLUSION

Leaving the intrathecal catheter in place in the postoperative period for 12 to 24 hours does not prevent PDPH.

Cell-type specific interaction of Neu differentiation factor (NDF/heregulin) with Neu/HER-2 suggests complex ligand-receptor relationships

The Neu/HER-2 receptor tyrosine kinase is overexpressed in some types of human adenocarcinomas, including tumors of the breast and the ovary. A 44 kDa glycoprotein that elevates tyrosine phosphorylation of Neu has been isolated and named Neu differentiation factor (NDF), or heregulin. Here we show that NDF affects tyrosine phosphorylation of Neu in human tumor cells of breast, colon and neuronal origin, but not in ovarian cells that overexpress the receptor. By using monoclonal antibodies (mAbs) to Neu, we found that the ovarian receptor is immunologically and biochemically similar to the mammary p185neu. Nevertheless, unlike breast-derived Neu, the ovarian protein did not display covalent cross-linking to radiolabeled NDF, and was devoid of ligand-induced association with phosphatidylinositol 3'-kinase. Direct binding analysis showed that NDF binds with high affinity (Kd approximately 10(-9) M) to mammary cells, but its weak association with ovarian cells is probably mediated by heparin-like molecules. Similar to the endogenous receptor, the ectopically overexpressed Neu of mammary cells, but not of ovarian and fibroblastic cells, exhibited elevated levels of NDF-induced phosphorylation and covalent cross-linking of the radiolabeled factor. Taken together, our results imply that NDF binding to cells requires both Neu and an additional cellular component, whose identity is still unknown, but its tissue distribution is more restricted than the expression of the neu gene.

Transient translocation of the cytoplasmic (endo) domain of a type I membrane glycoprotein into cellular membranes

The E2 glycoprotein of the alphavirus Sindbis is a typical type I membrane protein with a single membrane spanning domain and a cytoplasmic tail (endo domain) containing 33 amino acids. The carboxyl terminal domain of the tail has been implicated as (a) attachment site for nucleocapsid protein, and (b) signal sequence for integration of the other alpha-virus membrane proteins 6K and E1. These two functions require that the carboxyl terminus be exposed in the cell cytoplasm (a) and exposed in the lumen of the endoplasmic reticulum (b). We have investigated the orientation of this glycoprotein domain with respect to cell membranes by substituting a tyrosine for the normally occurring serine, four amino acids upstream of the carboxyl terminus. Using radioiodination of this tyrosine as an indication of the exposure of the glycoprotein tail, we have provided evidence that this domain is initially translocated into a membrane and is returned to the cytoplasm after export from the ER. This is the first demonstration of such a transient translocation of a single domain of an integral membrane protein and this rearrangement explains some important aspects of alphavirus assembly.

Can portable chest x-ray examination accurately diagnose lung consolidation after major abdominal surgery? A comparison with computed tomography scan

PURPOSE

To prospectively quantify the degree of accuracy of portable chest x-ray film examination in the detection of postoperative lung consolidations.

STUDY

Nineteen patients had a chest x-ray film and computed tomography (CT) scan the day before and 48 h following elective abdominal aortic replacement.

RESULTS

The diagnosis of lung consolidations by x-ray film examination showed sensitivity of between 0.33 and 1.00, depending on the lung zone considered (lower at the lung bases). Specificity always was greater than 0.79. Radiologic lung volume decreased 16 percent postoperatively (p < 0.01) on average and noninflated parenchyma increased by a factor of 3 (p < 0.0001). Postoperatively, PaO2 correlated with the amount of condensed lung by CT scan (p < 0.002).

CONCLUSION

In postoperative conditions, x-ray film examination is a method which presents good specificity but poor sensitivity in the diagnosis of lung consolidations.

Effect of preoperative normovolemic hemodilution on left ventricular segmental wall motion during abdominal aortic surgery

Preoperative normovolemic hemodilution (PNH) has been proposed for patients scheduled to undergo aortic surgery. Coronary artery disease is frequent in these patients. The aim of the study was to assess the effect of PNH on hemodynamics and segmental wall motion (SWM) evaluated by transesophageal echocardiography in such patients. Twenty patients with coronary artery disease were allocated randomly to either PNH or no PNH; PNH was performed after anesthetic induction using dextran 60,000. Patients were operated on under general anesthesia and monitored intraoperatively with electrocardiographic lead CM5, radial and pulmonary artery catheters, and transesophageal echocardiography positioned to obtain a short-axis view. Hemodynamic and transesophageal echocardiographic data were collected after anesthetic induction and after PNH, before and 5 min after aortic clamping, after unclamping, and at the end of surgery. Aortic clamping induced a significant increase in systemic vascular resistance and arteriovenous difference in oxygen and a decrease in cardiac index (P < 0.05), but the effect of aortic clamping was inversely related to hemodilution. The SWM score (graded from 1 = normal to 5 = dyskinesia) was significantly increased after aortic clamping, mainly in the anterior segment (P < 0.05). Four patients in the control (no PNH) group and one in the PNH group developed new SWM abnormalities indicative of myocardial ischemia during surgery (P = NS). This study suggests that PNH may improve hemodynamic tolerance to aortic clamping in patients with coronary artery disease. The observed changes in SWM indicate that PNH may not worsen myocardial ischemia in patients scheduled to undergo aortic surgery.

Functional implication of disulfide bond, Cys250 -Cys283, in bovine chymosin

The reduction, carboxymethylation and mercuration of disulfide bond, Cys250-Cys283, located on the surface of bovine chymosin molecule resulted in the loss of about 25% of enzyme activity, suggesting that Cys250-Cys283 is not intimately involved in catalytic mechanism. Cys250 and Cys283 were substituted with Asp. and Ser. by site- directed mutagenesis of the structural gene coding for bovine prochymosin B. All three mutants (C250D/C283S, C250D, C283S) failed to be activated to chymosin in acid, indicating that Cys250-Cys283 might have some contribution to the correct refolding of the unfolded prochymosin.

Single- versus triple-lumen central catheter-related sepsis: a prospective randomized study in a critically ill population

PURPOSE

A prospective randomized study was conducted over a 23-month period in an adult medical-surgical intensive care unit to determine whether triple-lumen catheters reduce the need for peripheral vascular access and whether they are associated with a higher rate of infection than single-lumen catheters.

PATIENTS AND METHODS

After the insertion route, internal jugular or subclavian, was selected by the physician, patients were randomized either to single-lumen or triple-lumen catheter groups. Complementary peripheral vascular access was allowed in both groups. Catheters were removed according to preestablished defined reasons: suspicion of catheter-related sepsis, uselessness of central venous access, duration of catheterization of more than 21 days, discharge from the intensive care unit, or death.

RESULTS

Data on 129 central venous catheters were collected from 91 consecutive patients. Twenty-five of 68 patients from the single-lumen group and 1 of 61 patients from the triple-lumen group needed peripheral vascular access (p less than 0.001). Catheter-related sepsis rates, defined either by clinical signs and positive qualitative tip cultures (8.9% versus 11.5%) or by quantitative tip cultures (16.2% versus 11.5%), were identical in the single-lumen and triple-lumen groups (type II error: 8%).

CONCLUSION

In intensive care units, the use of triple-lumen catheters is associated with a dramatic decrease in the need for peripheral vascular access. The incidence of central venous catheter-related sepsis appears identical for single- and triple-lumen catheters.

[The effect of 211At labelled monoclonal antibody against gastric cancer on DNA, RNA and protein synthesis in gastric cancer cell]

By means of nuclide precursor incorporation, the effects of 211At labelled monoclonal antibody against gastric cancer (211At-3H11McAb) on DNA, RNA and protein synthesis in gastric cancer cell were studied. The results show that 211At-3H11McAb and Na211At-3 inhibit 3H-TdR, 3H-UR and 3H-Leu incorporation, especially 3H-UR incorporation, into gastric cancer cell at 3.7 x 10(4)Bq and 1.85 x 10(5)Bq; the inhibiting rates depend on concentration. The DNA biosynthesis in gastric cancer cell gradually recover after the drug is removed, suggesting that the drug should exert an inhibiting action on DNA biosynthesis in tumor cell through interference of DNA metabolism.

A dose-range study of intrathecal meperidine combined with bupivacaine

Twenty-one patients were included in a randomized study to receive either 10 mg of 0.5% hyperbaric bupivacaine alone or combined with 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5 mg.kg-1 meperidine for spinal anaesthesia. Sensory blockade was assessed by pin prick, motor blockade by the Bromage scale, and postoperative analgesia by VAS scores and by the time before the first demand for analgesia. Spinal meperidine did not change the duration of sensory blockade, but induced a dose-related increase in postoperative efficient analgesia. Spinal meperidine might be considered as a means to obtain postoperative analgesia in the hours immediately following surgery.

Test of 20 similar intensive care ventilators in daily use conditions--evaluation of accuracy and performances

Infrequent control, aging of components, may compromise the accuracy of ICU ventilators. In order to assess the reliability of ventilators during their clinical use, we bench tested a group of 20 CPU1 ventilators (Ohmeda) sampled at random in several ICU units. We found major leaks in 5 ventilators, attributable to the disposable tubings used in these systems. Mean error in expired tidal volume and corresponding standard deviation (precision) were greater than 100 ml in two. Positive end expiratory pressure measurement comprised a mean error higher than 2 cm H2O in 40% of the ventilators tested. The valve opening pressure threshold was correlated to the inspiratory flow (r = 0.81) contrary to the valve opening delay (average 138 +/- 40 ms). These two parameters did not correlate with the age of the ventilator. Our study addresses the need for periodic control of ventilator performance in order to minimize the risks of errors and malfunctions.

[A study of 11 ventilators for anesthesia: laboratory testing]

Eleven anaesthesia ventilators were instrumentally tested under various conditions. They included: Excel and Modulus II Plus (Ohmeda); 710 and Servo anaesthesia circle 985 (Siemens); Jollytronic (Soxil) and Elsa (Engström); SA2 and Cicero (Dräger); ABT 4,300 (Kontron); Monnal A and the prototype Alys (Taema). The test circuit comprised a two compartment model lung, a pneumotachograph, a pressure gauge in the "airway". The volume was calculated as the integral of flow rate. Each machine was calibrated by the firms' technicians. Before each test, the pneumotachograph was calibrated using a 11 air syringe and the pressure gauge with a 5 cm water column. Each machine ventilated the model lung for 30 min before starting the tests. There were five tests: 1) reliability of the machine's spirometer, 2) reliability of the ventilation rate, 3) reliability of pressure measurements, 4) effect of increasing fresh gas flow on spirometry, 5) effect of increasing downstream resistances. In usual simulated ventilatory conditions, all the machines accurately delivered the setted ventilation and spirometric measurements were with minimal error only. Several ventilators (SA2, Excel, 710, Elsa, ABT 4,300) did not succeed in maintaining their performances when compliance was strongly decreased or resistance of the test lung notably increased. Resistance in the circuit during simulated spontaneous ventilation was < 3.6 cmH2O.l-1.s-1. Increasing fresh gas flow raised the minute volume delivered in six ventilators. It is concluded that, during extreme ventilatory conditions, the inspired volume must be adjusted so as to maintain the inspired tidal volume. However, ventilators which increase inspiratory time in response to an increased mechanical load cannot be adjusted by this way.

Selection of high-level abamectin resistance from field-collected house flies, Musca domestica

Abamectin is a novel, highly promising insecticide with activity against many pests. To determine if resistance to abamectin could occur, we collected house flies from several New York dairies and selected them in the laboratory. Resistance developed rapidly and to a high level (36 or greater than 60,000-fold, depending upon test technique and/or adjuvant) that could not be overcome by the synergists piperonyl butoxide or S,S,S-tributylphosphorotrithioate. There was no increase in (cross)resistance to crotoxyphos, dichlorvos, dimethoate, tetrachlorvinphos, permethrin, dieldrin or lindane following abamectin selection. Our results suggest the potential for abamectin resistance is high, at least in house flies, and that the judicious use of abamectin will be needed to prolong its usefulness as an insecticide.

Demonstration of immuno-bound alkaline phosphatase by a direct lead method. Optimization of reaction parameters by microdensitometry using computer-aided image processing

Antigens labelled by the immunohistochemical alkaline phosphatase anti-alkaline phosphatase (APAAP) method can be visualized by a lead capture technique. Optimal conditions of the reaction, evaluated by microdensitometry using computer-aided image processing, are described.

[Analysis of failures of spinal anesthesia as a function of practice development in a university hospital]

This study is a retrospective analysis of 303 consecutive spinal anaesthesia performed in orthopaedic patients of a University Hospital between January and December 1990. Failure of spinal anaesthesia was defined as the requirement for general anaesthesia to perform surgery. The parameters studied as possible risk factors of failure were patients demographics, local anaesthetic agents and solutions and techniques of spinal anaesthesia (single injection versus continuous spinal anaesthesia). Failures were related to inadequate or incomplete extension of sensory blockade or to difficulties to perform spinal injection. Continuous spinal anaesthesia was performed in 209 patients mostly with 0.5% isobaric bupivacaine, while 94 patients received a single injection of either hyperbaric 0.5% tetracaine with adrenaline or 0.5% bupivacaine or 5% lidocaine. Failures occurred in 6.3% of the cases but were significantly less frequent with continuous spinal anaesthesia (4.8%) than with the conventional technique (9.6%). The incidence of failure was higher with hyperbaric tetracaine (11.1%) confirming its poor reliability. Inadequate extension of the anaesthetic block was the main cause of failure whatever the spinal anaesthetic technique. These results point out the reliability of continuous spinal anaesthesia but problems may occasionally occur due to spinal catheter misplacement.

[Experimental study of glucosylated low density lipoprotein metabolism and atherosclerosis]

The effect of LDL glucosylation on its pathway was assessed. Human serum LDL was isolated by density gradient ultracentrifugation and its purity was identified by polyacrylamide gel electrophoresis. LDL was radioiodinated with 125I by iodine monochloride. LDL radioreceptor assay was performed and intracellular total cholesterol was determined in cultured human fibroblasts. Maximal binding affinity (Bmax) of LDL receptor was 47 ng LDL/mg cell protein, Km was 9.4 micrograms/ml. The receptor mediated binding, internalization and degradation of glucosylated LDL were significantly decreased compared with control LDL, but total cholesterol content of cultured fibroblasts incubated with glucosylated LDL was significantly higher than those incubated with control LDL. The results suggested that glucosylation of LDL might be an important mechanism for the high incidence of disturbed lipid metabolism and atherosclerosis in diabetic patients.

Site-directed mutagenesis of recombinant rat DNA polymerase beta: involvement of arginine-183 in primer recognition

By site-directed mutagenesis using synthetic oligonucleotides, amino acid residues 181Phe-Arg-Arg183 of recombinant rat DNA polymerase beta were replaced by other amino acids to clarify the roles of these residues in the DNA synthesizing reaction. Replacement of Phe-181 by alanine reduced the enzyme activity only 30%. Replacement of Arg-182 by alanine and glutamine resulted in reduction of the activity by about 67% and 95%, respectively. The Arg-182----Gln replacement increased the binding strength to single-stranded DNA but did not significantly change the Km's for the primer and dTTP, suggesting that Arg-182 is involved in modulation of binding to the template rather than to the primer or deoxyribonucleoside triphosphate. Replacement of Arg-183 by Gln resulted in reduction of the activity by about 95%, and this change, although causing little change in binding strength to single-stranded DNA, resulted in a 3-4-fold increase in the Km's for the primer and deoxyribonucleoside triphosphate. A more dramatic change was observed when Arg-183 was replaced by Ala, which resulted in a 99.98% reduction of enzyme activity. Although the Km for deoxyribonucleoside triphosphate of this mutant enzyme was hardly changed, that for the primer increased 159-fold. Therefore, it is concluded that Arg-183 occupies an important part of the primer recognition site of DNA polymerase beta.