The effect of pentobarbital anaesthesia upon the extracellular fluid volume in the dog,studied by continuous infusion and single injection methods

The effect of pentobarbital anaesthesia on the volume and ionic composition of the extracellular space was studied in adult male mongrel dogs with permanent catheters in aorta and pulmonary artery. The extracellular fluid volume (Q ^ec ) was determined with: a) methods based on equilibration of the indicator throughoutQ ^ec by continuous infusion; b) methods based on the assumption that after a single injection of indicator the plasma indicator concentration equals extracellular indicator concentration as long as the log plasma indicator concentration-time curve is linear; c) a single injection method based on a closed flow system model with a single inflow and a single outflow orifice. The measurements were made before and 30 and 90 min after induction of anaesthesia. Thirty minutes after induction of anaesthesiaQ ^ec as determined with the method sub a, had decreased by about 10% and remained so during the following 60 min. The values ofQ ^ec as calculated by the method sub c fairly agreed withQ ^ec as determined with the method sub a and also showed a decrease ofQ ^ec during pentobarbital anaesthesia. The procedures sub b overestimatedQ ^ec and yielded a seemingly higherQ ^ec during anaesthesia, because the boundary conditions for these procedures do not apply. The haemoglobin concentration decreased by about 10% and the lactate concentration by about 50%. The phosphate concentration increased by about 25% while the other electrolyte concentrations (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^–, HCO ₃ ^– ) did not change. A respiratory acidosis developed during the first 30 min and almost disappeared in the following 60 min. Possible explanations for the pentobarbital-induced concentration ofQ ^ec are discussed.     

Pitfalls in acid/base experiments with conscious dogs

Arterial pH and blood gases were measured at intervals in conscious dogs after their first human contact of the day. Blood was sampled through an indwelling catheter in the aorta without disturbing the animals. It appeared that in the first 90 min arterial PO₂, oxygen saturation and haemoglobin concentration significantly declined. PCO₂ and pH changed less consistently when the acid/base status of the dogs was normal, but when a non-respiratory acidosis was present there was a significant decrease in pH and a significant increase in PCO₂. Arterial pH and blood gases were also measured before and after feeding the animals. It appeared that an appreciable metabolic alkalosis developed within 2 h after a meal. The alkaline tide was accompanied by a trend to higher values for PCO₂. It is concluded that, after a period of seclusion, renewed human contact causes behavioural changes in a dog, which may result in appreciable transitory changes in arterial pH and blood gas values. Blood sampling from conscious dogs should therefore take place after a proper period of habituation; preferably, a few samples should be taken at intervals to check that a steady state has been reached. If possible, blood should be collected before feeding; in any case the relationship in time of blood sampling to feeding should be constant throughout.     

Carbon-11 labelled tyrosine to study tumor metabolism by positron emission tomography (PET)

To measure the rate of protein synthesis in human neoplasms by positron emission tomography, we prepared no carrier added DL-(1-¹¹C)-tyrosine by ¹¹C-carboxylation of the appropriate -lithioisocyanide followed by hydrolysis of the isocyanide function and removal of the protecting methoxy group. The purification, resolution and solvent switch to saline was performed by high performance liquid chromatography (HPLC). DL-(1-¹¹C)-Tyrosine in 0.1 N NaH₂PO₄ buffer was prepared with a radiochemical yield of 8%–16% (EOS, 35 min). The enantiomeric separation and solvent switch to saline were achieved in 5 min and 10 min respectively. Consequently L-(1-¹¹C)-tyrosine in physiological saline was obtained in 2%–4% radiochemical yield. Tumor accumulation in rats with the experimental WALKER 256 carcinosarcoma was observed for both the L- and D-isomer. Using positron emission tomography a tumor/muscle ratio of two was observed for the L-isomer 15 min after injection. The corresponding figure for the D-isomer was 2.5. The first clinical results with DL-(1-¹¹C)-tyrosine show accumulation of radioactivity in meningioma, a primary breast carcinoma and in liver metastases of a colonic carcinoma.     

Prostacyclin formation in undelayed and delayed pig flank flaps

Summary A specific 6-keto-prostaglandin PGI₂ radioimmunoassay (R.I.A.) was used to follow tissue prostacyclin formation in a series of acute and delayed pig flaps. Each flap measured 12×5 cm and four white, female ehester pigs, averaging 21 kgs in weight, were used. Flap tissue samples were taken at day 0 (control) 1–8, 10, 14, 17 and 21 using 0.4 mm diameter cork borer. Prostacyclin formation started to rise on day 4 and extended until the 10th day in both types of flaps. The hyperemic circulation that occurred following delay procedure is associated with a rise in prostacyclin production whereas the higher rise in prostacyclin in the undelayed flap is due to the reactive inflammation.     

Immune responses against SARS-coronavirus nucleocapsid protein induced by DNA vaccine

The nucleocapsid （N） protein of SARS-coronavirus （SARS-CoV） is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DHSalpha and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobutins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity （DTH） and CD^8＋ CTL responses to N protein.     

Remifentanil as a single drug for extracorporeal shock wave lithotripsy: a comparison of infusion doses in terms of analgesic potency and side effects

This randomized, double-blind study was designed to evaluate analgesic effectiveness and side effects of two remifentanil infusion rates in patients undergoing extracorporeal shock wave lithotripsy (ESWL) for renal stones. We included 200 patients who were administered remifentanil either 0.05 microg x kg(-1) x min(-1) (n = 100) or 0.1 microg x kg(-1) x min(-1) (n = 100) plus demand bolus of 10 microg of remifentanil via a patient-controlled analgesia (PCA) device. No other sedating drugs were given. The frequencies of PCA demands and deliveries were recorded. Arterial blood pressure, oxygen saturation, and respiratory rate were recorded throughout the procedure; postoperative nausea and vomiting (PONV), dizziness, itching, agitation, and respiratory depression were measured posttreatment. Visual analog scale (VAS) scores were taken preoperatively, directly postoperatively, and 30 min after finishing the procedure. There were no statistically significant differences in the frequency of PCA demands and delivered boluses or among perioperative VAS scores. The extent of PONV and frequency of dizziness and itching immediately after and dizziness 30 min after the end of treatment were significantly reduced in the smaller dose group. We conclude that a remifentanil regimen of 0.05 microg x kg(-1) x min(-1) plus 10 microg demands is superior to 0.1 microg x kg(-1) x min(-1) plus demands, as there was no difference in the VAS scores recorded between groups and it has a less frequent incidence of side effects in patients receiving ESWL. IMPLICATIONS: Remifentanil is an appropriate analgesic choice for patients undergoing extracorporeal shock wave lithotripsy (ESWL) therapy, as it has both fast onset and offset times. We studied remifentanil as a sole drug for ESWL and have shown that an infusion rate of 0.05 microg x kg-1 x min-1 plus patient-controlled analgesia demands of 10 microg provides adequate analgesia and has significantly less side effects than a dose of 0.1 microg x kg-1 x min-1 plus 10 microg demands.     

Initiation and Maintenance of Weight Loss after Laparoscopic Adjustable Gastric Banding. The role of Outcome Expectation and Satisfaction with the Psychosocial Outcome

Background  A premise of this study was that different psychological processes would predict the initiation and maintenance of weight loss after surgery for morbid obesity. Our aim was to examine whether more favorable preoperative expectations of psychosocial outcomes predict weight loss in the first year after laparoscopic adjustable gastric banding (LAGB) and whether postoperative satisfaction with these outcomes predicts weight maintenance in the second year after the operation. Methods  Six months before and 1 year after surgery, the “Obesity Psychosocial State Questionnaire” was filled out by 91 patients (77 female, 14 male, mean age 45 ± 9 years, mean preoperative body mass index 47 ± 6 kg/m²). We evaluated the preoperative outcome expectations and the postoperative satisfaction for the seven domains of psychosocial and physical functioning of this questionnaire, as well as the correlations between these scores and both weight loss and weight maintenance. Results  Patients showed high satisfaction with psychosocial outcomes after LAGB in all seven domains (p < 0.001), even though the improvement was less than expected in five of the domains (p ≤ 0.01). While weight loss 1 year after the operation was related to satisfaction with psychosocial outcomes (p ≤ 0.05), preoperative expectations were not related to weight loss in the first year after surgery, and satisfaction with the outcomes was not related to weight maintenance in the second year after surgery. Conclusion  Our study suggests that surgically induced effects of weight loss and weight maintenance are achieved independently of the patient’s preoperative expectations of and postoperative satisfaction with the psychosocial outcomes.