Zonal differences in effects of HGF/SF and EGF on DNA synthesis in hepatocytes under fed or starved conditions

Zonal differences of DNA synthesis in hepatocytes induced by hepatocyte growth factor and/or scatter factor (HGF/SF) and epidermal growth factor (EGF) were investigated using male Wistar rats under fed or starved conditions. Overall, DNA synthesis was greater in fed rats than in starved rats. The predominance of EGF in periportal hepatocytes (PPH) on zonal DNA synthesis was reversed by starved conditions, but the predominance of HGF/SF on zonal DNA synthesis in perivenous hepatocytes (PVH) was not influenced by nutritional conditions. 125I-labeled EGF and 125I-labeled HGF/SF-receptor binding studies revealed no significant difference between PPH and PVH in starved or fed rats. To investigate the mechanism of the signal transduction pathway, we used genistein, an inhibitor of tyrosine kinase. Genistein had different effects on zonal difference in EGF and HGF/SF. In EGF, 1 microgram/ml genistein abolished zonal differences, but in HGF/SF 1 microgram/ml genistein did not abolish zonal differences. These data suggest that, in contrast to HGF/SF, zonal difference of DNA synthesis by EGF was dependent on nutritional conditions and DNA synthesis induced by HGF/SF and EGF might be related to tyrosine kinase, but the influence of tyrosine kinase on DNA synthesis was different between HGF/SF and EGF.

[Effects of cardiac output on blood and tissue pH during general anesthesia with constant ventilation]

We investigated the effects of cardiac output on blood and tissue pH in 106 adult patients undergoing cardiac or non-cardiac surgery under general anesthesia. After anesthetic induction, the minute ventilation volume was kept constant at 10 ml.kg-1 x 10 cycles.min-1. A pulmonary artery catheter and a nasogastric tube incorporating a tonometer were inserted. During surgery, cardiac index (CI), pH, Pco2, BE, So2 and Hb of arterial and mixed venous blood as well as gastric intramucosal pH (pHi) were measured simultaneously. Oxygen uptake index (Vo2I) and blood CO2 contents were calculated. The measurements were repeated every 10 to 20 minutes during surgery or during the prebypass period. Two patients with preoperative cardiogenic shock were excluded from data analysis because of development of severe acidosis and 624 sets of data from 104 patients were analyzed. Arterial and mixed venous pH correlated negatively with CI. Blood Pco2 and base excess (BE) correlated positively and negatively, respectively, with CI. Blood lactate concentration measured 142 times in the last 30 patients correlated positively with CI. Vo2I correlated positively with CI and Paco2 correlated positively with Vo2I. Veno-arterial differences in Pco2 and Cco2 correlated negatively with CI. Due to the difference, Caco2 correlated positively with CI, while Cvco2 did not correlate with CI. pHi correlated negatively with CI but only marginally. By multiple regression analysis, pHi was not affected significantly by CI, while it showed positive correlation with pHa, Hb, Sao2 and negative correlation with blood temperature. When cardiac output increased, blood pH decreased due to increased Pco2 and decreased BE. An increase in Paco2 might result from both an increase in Vo2 or Vco2 and decreased ventilation-to-perfusion ratio. A decrease in BE might result from increased washout of acids (e.g. lactate) from the tissue to the central circulation. In contrast to blood pH, pHi or tissue pH was not affected significantly by cardiac output unless patients were in cardiogenic shock.

[Anesthesia induction for laryngeal mask insertion--comparison among sevoflurane, isoflurane and propofol]

We compared the patient's response to laryngeal mask (LM) insertion and hemodynamics among three anesthesia induction methods; S group used sevoflurane and slowly increased to 5% in 50% nitrous oxide; I group used isoflurane and slowly increased to 3% in 50% nitrous oxide; and P group used 2.5 mg.kg-1 propofol with 0.2 microgram.kg-1 fentanyl. Thirty patients, 35 to 65 years, for elective mastectomy were the subjects of study in each of the three groups. Preanesthetic medication was composed of i.m. injection of 0.5 mg atropine and 5 mg midazolam 30 min. prior to the induction. The number of patients with difficult insertion or demonstrating body movement or gagging in each group was in the order of P group > I group > S group. Blood pressure (BP), heart rate (HR) and rate pressure product (RPP) in the P group were significantly lower than those in the other two groups. I group showed significant increase in BP, HR and RPP. It was concluded that sevoflurane enabled the most smooth insertion of LM among the three methods of anesthesia with the least hemodynamic change.

[Evaluation of estimated blood concentration of propofol on wake-up using "ConGrase", a software to control the syringe pump for propofol infusion]

We developed a software to control a Graseby 3500 syringe pump for propofol infusion through the serial port of Apple Macintosh/Power-Macintosh computer. This software, "ConGrase", was developed with Metrowerks CodeWarrior Professional (CWP 1) and PowerPlant framework using C++. ConGrase communicates with the syringe pump at least every three seconds, and calculates the estimated blood concentration (EBC) of propofol based on the amount of propofol actually infused by applying either the Euler or Runge-Kutta method using the three-compartment pharmacokinetic model. The parameter sets reported by Gepts et al. are used. ConGrase was released at the 44 th Annual Meeting of the Japan Society of Anesthesiology, and is distributed freely. The mean and S.D. of the emergence EBC calculated by ConGrase were 1.22 micrograms.ml-1 and 0.16 microgram.ml-1, respectively. These values are almost the same as values already reported outside Japan. The necessary wake-up time can be calculated with this estimated concentration. With this system, anesthetists can control the EBC at the required level and avoid long delays before the patients wake up after anesthesia.

[Total intravenous anesthesia with propofol is advantageous than thiopental-sevoflurane anesthesia in the recovery phase]

A randomized, prospective and multi-institutional study was performed to investigate whether different anesthetic methods affected differently the quality of recovery from anesthesia. Two hundred and eleven patients were allocated to one of two groups; total intravenous anesthesia (TIVA) with propofol and fentanyl (group P, n = 107) and general anesthesia with thiopental, sevoflurane and nitrous oxide (group TS, n = 104). The rapidity of emergence from anesthesia and postoperative incidence of nausea, vomiting, and headache were compared between the two groups. The group P showed significantly shorter emergence times for verbal command responses (7.4 +/- 5.6 min), extubation (10.0 +/- 6.0 min) and orientation (13.1 +/- 7.8 min) than the group TS (9.1 +/- 5.0 min, 11.7 +/- 6.2 min, 16.4 +/- 7.9 min, respectively). The postoperative incidence of vomiting was not significantly different between the two groups (3.7% in the group P and 9.6% in the group TS), but the postoperative incidences of nausea and headache were significantly lower in the group P compared with the group TS (10.3%, 17.8%, respectively in the group P and 34.6%, 29.8%, respectively in the group TS). We conclude that TIVA with propofol is advantageous than thiopental-sevoflurane anesthesia in the recovery phase.

[Body temperature changes during combined inhalational and epidural anesthesia]

We investigated the effects of combined inhalational and lumbar epidural anesthesia on body temperature in 8 women for long-lasting lower abdominal surgery. Probes for forehead deep temperature and skin-surface temperatures were placed on the forehead, forearm, fingertip and toe tip on patients' arrival at the operating room. Tympanic membrane temperature was also measured. Lumbar epidural block was established with 2% lidocaine 10 ml. Twenty minutes later, general anesthesia was induced and maintained with nitrous oxide-oxygen-isoflurane. Epidural anesthesia was maintained with intermittent dose of 1% mepivacaine. Before the end of surgery, isoflurane concentration was increased from about 0.5% to 2% and was maintained at this level for 20 minutes, after which it was reduced. With the establishment of epidural blockade, toe tip temperature increased and fingertip temperature decreased, while core temperature remained unchanged. After induction of general anesthesia, fingertip temperature increased, while core temperature decreased. The core temperature drop during the anesthetic induction was significantly affected by the increase in toe tip temperature. Before the end of surgery, core temperature remained at a reduced but constant level, while fingertip temperature continued to decrease. With the application of 2% isoflurane, fingertip temperature increased, while core temperature decreased. The core temperature drop was significantly affected by the increase in fingertip temperature. After the reduction of isoflurane concentration, these temperature changes were reversed fully. At the end of surgery, fingertip temperature decreased, while core temperature increased. During mild hypothermia, isoflurane depressed thermoregulatory vasoconstriction dose-dependently until its concentration reached 0.6-0.7%. In conclusion, anesthetics-induced redistribution of body heat significantly affects the core temperature throughout anesthesia. Peripheral hypothermia results in core temperature drop when the redistribution is induced by anesthetics. Thermoregulatory vasoconstriction may not only suppress heat loss but also increase core temperature through centralization of body heat.

[The duration of action of vecuronium is unchanged when administered with propofol]

We examined the difference in the duration of action of vecuronium injected through a venous line infused with propofol and the duration of vecuronium infused into another venous line without propofol, in order to investigate the interaction between vecuronium and propofol within the intravenous lines. The subjects of the study are 8 patients, (ASA grade 1 or 2, aged from 20 to 50 years, 6 males and 2 females), who had undergone elective operations under general anesthesia. The mean duration of action of vecuronium injected through the venous line infused with propofol was 32.3 +/- 9.0 (min), while that for vecuronium injected through the venous line without propofol was 32.1 +/- 8.6 (min). There was no significant difference in the duration of action of vecuronium between the two conditions. We conclude that since vecuronium can be injected through the venous lines infused with propofol without interaction, there is no need for an additional venous line without propofol when vecuronium is administered under propofol anesthesia.

Inorganic fluoride kinetics and renal and hepatic function after repeated sevoflurane anesthesia

After repeated exposure to inhaled anesthetics, the hepatic function and metabolism of anesthetics may change. The purpose of this study was to investigate inorganic fluoride (F-) kinetics and renal and hepatic function after repeated exposure to sevoflurane. Ten patients (aged 40-70 yr) who had received sevoflurane anesthesia with a gas flow of 6 L/min for neurosurgery twice in 30-90 days were studied. Serum and urine F- concentrations were measured up to 24 h after anesthesia. Blood urea nitrogen, serum creatinine, serum and urine beta2-microglobulin, urine N-acetyl-beta-D-glucosaminidase, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin concentrations were measured up to 7 days after anesthesia. The area under the curve (AUC) of serum and urine F- concentration and half-life of serum F concentration were calculated. Urine beta2-microglobulin, AST, and ALT increased to abnormal levels after both anesthesias, with no difference between anesthesias. No measured variables, AUC of serum and urine F- concentration, or half-life of serum F- concentration showed any differences between the first and second anesthesias. In conclusion, the second exposure to sevoflurane with a high gas flow of 6 L/min in 30-90 days did not change the hepatic and renal function or affect the metabolism of sevoflurane.

IMPLICATIONS

We studied the changes of metabolism of sevoflurane and hepatic and renal function after repeated sevoflurane anesthesia in 30-90 days. There were changes indicative of mild liver and kidney injury after sevoflurane anesthesia, but repeated exposure to sevoflurane did not enhance these changes.

Liver function after sevoflurane or isoflurane anaesthesia in neurosurgical patients

PURPOSE

Although both sevoflurane and isoflurane are thought to be less hepatotoxic than halothane or enflurane, recent case reports have described liver injury after sevoflurane or isoflurane anaesthesia. There are no studies comparing liver function after sevoflurane or isoflurane anaesthesia. The purpose of this study was to compare serum liver enzyme concentrations in patients receiving either sevoflurane or isoflurane anaesthesia prospectively.

METHODS

Ninety patients scheduled for elective neurosurgery were studied. Serum concentrations of aspartame aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBil), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GTP), and lactate dehydrogenase (LDH) were measured before and, 1, 2, 3, 7, and 14 days after either sevoflurane (45 patients) or isoflurane (45 patients) anaesthesia.

RESULTS

AST, ALT and GTP increased peaking seven days after anaesthesia, especially in the isoflurane group. The numbers of patients with abnormal values in AST and ALT were not different in the isoflurane from that in the sevoflurane group. The increase in TBil peaked one day after anaesthesia in both groups.

CONCLUSION

Even in a small number of patients, isoflurane induced an elevation of serum levels of liver enzymes more frequently than did sevoflurane three to 14 days after anaesthesia.

Liver and renal function after repeated sevoflurane or isoflurane anaesthesia

PURPOSE

To compare retrospectively liver and renal function after repeated exposure (twice) to sevoflurane or isoflurane.

METHODS

Sixty patients were studied for liver and renal function after repeated exposure within 30 to 180 days to sevoflurane (30 patients) or isoflurane (30 patients). Serum concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBil), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GTP), blood urea nitrogen (BUN) and creatinine (Cr) were measured before and, 1, 3, 7, and 14 days after surgery. Qualitative analyses of urinary protein and glucose were done 1, 3, and 7 days after surgery.

RESULTS

The number of patients with abnormal values in AST, ALT and GTP was larger in the isoflurane than in the sevoflurane group. BUN and Cr were within normal range after anaesthesia in either group. Renal excretion of protein and glucose increased one and three days after anaesthesia with no difference between the anaesthetics. None of the variables showed differences between the first and second anaesthesia after either anaesthetic.

CONCLUSION

Repeat exposure to sevoflurane or isoflurane within 30 to 180 days had no additional risk of increasing serum concentration of liver enzymes or increasing urinary excretion of protein and glucose compared with the first exposure to the same anaesthetic.

[Long lasting epidural anesthesia for a morbidly obese patient]

A forty-six year old woman (136 cm, 115 kg), with body mass index (BMI) of 62.2, was scheduled for osteotomy because of postoperative infection and pseudoarthrosis of the right lower leg. During the post two years, the patient had received several orthopedic surgeries under spina anesthesia, which repeatedly accompanied intraoperative respiratory difficulties. At the age of thirty one, she weighted more than 100 kg and needed cardiopulmonary resuscitation during cesarean section under general anesthesia. Considering the past history of anesthesic complications, we decided to perform epidural anesthesia with a written informed consent from the patient. Due to technical difficulties, the operative procedures took six hours and forty-five minutes without complications related to anesthesia. This case demonstrates the necessity of safe and comfortable anesthesia for morbidly obese patients.

Midazolam improves postoperative epidural analgesia with continuous infusion of local anaesthetics

PURPOSE

Midazolam has been shown to have an analgesic effect by single shot epidural administration. In this study, the effect of midazolam on continuous epidural infusion of bupivacaine was investigated to find a better combination for postoperative analgesia.

METHODS

Sixty patients scheduled for gastrectomy were divided into three groups of 20. The following mixtures, in 40 ml, were infused continuously over 12 hr after surgery; 40 ml bupivacaine 0.5% in Group C, bupivacaine 0.5% 38 ml + 10 mg midazolam in Group M10, and bupivacaine 0.5% 36 ml + 20 mg midazolam in Group M20. If necessary, 50 mg indomethacin suppository was administered. Blood pressure, heart rate, respiratory rate, analgesia score, and sedation score were monitored for 12 hr after surgery. Amnesia and frequency of the administration of indomethacin suppository were also noted.

RESULTS

Blood pressure, heart rate and respiratory rate showed no differences among the groups. Greater sedation was seen in Groups M10 and M20 compared with Group C during first 120 min (P < 0.05). The number of patients with memory was larger in Group C (18) than in Group M10 (10, P = 0.006) and Group M20 (6, P < 0.001). Better analgesia was obtained in patients receiving midazolam than in Group C (P < 0.05). The frequency of the indomethacin administration was 2.0 +/- 1.1 (SD) in Group C, which was larger than in Group M10 (1.1 +/- 0.9, P = 0.035) and Group M20 (1.2 +/- 0.7, P = 0.039).

CONCLUSION

Adding midazolam to a continuous epidural infusion of bupivacaine provides better analgesia, amnesia and sedation than bupivacaine alone without side effects in patients undergoing laparotomy.

Effect of diluent volume on post-operative analgesia and sedation produced by epidurally administered midazolam

We have studied the optimal diluent volume for post-operative analgesia and sedation produced by epidurally administered midazolam after upper abdominal surgery. Sixty patients were randomly allocated to four groups of 15 patients. When patients complained of pain after surgery, epidural midazolam 0.05 mg kg-1 in 3 mL saline (Group A), in 5 mL saline (Group B), in 10 mL saline (Group C) or in 15 mL saline (Group D) were injected as a bolus. The sedation was better and lasted longer in groups B and C than in the other two groups. Groups B and C also had significantly more extensive areas of analgesia than groups A and D from 30 min after the administration of midazolam. The interval to the second request for an analgesic was significantly shorter in Group D than in the other three groups. Memory retention of the pin-prick examination was reported by four patients in Group A. The present results indicate that 5-10 mL saline is the optimal volume for epidural injection when using midazolam 0.05 mg kg-1 for post-operative analgesia following upper abdominal surgery.

The effects of age and gender on the optimal premedication dose of intramuscular midazolam

We conducted a double-blind study on the effects of age and gender on the optimal premedication dose of i.m. midazolam. We randomly divided 100 male and 100 female patients in each of three age groups: A = 20-39 yr, B = 40-59 yr, and C = 60-79 yr (total 600 patients) into five groups according to midazolam dosage: 0.04, 0.06, 0.08, 0.10, and 0.12 mg/kg. Midazolam was injected i.m. with atropine 0.01 mg/kg 15 min before the induction of anesthesia. Blood pressure (BP), heart rate, respiratory rate, oxygen saturation (SpO2), sedation level, tongue root depression, eyelash reflex, and anterograde amnesia were monitored. There were no significant differences between male and female patients in any variables in any age. Decrease of SpO2 and loss of eyelash reflex were seen with midazolam 0.10 mg/kg in Group A, and with 0.08 mg/kg in Group B. In Group C, decreases in BP and SpO2, loss of eyelash reflex, and depression of the tongue root were observed with midazolam 0.06 mg/kg. In conclusion, the optimal doses of i.m. midazolam administered 15 min before the induction of anesthesia in male or female patients were 0.08, 0.06, and 0.04 mg/kg for Groups A, B, and C, respectively.

IMPLICATIONS

Midazolam is the most widely used preoperative anxiolytic drug. Our purpose was to evaluate the optimal dose of i.m. midazolam that would maximize the desired effects and minimize the side effects in a common clinical setting. Results indicate that age, but not gender, should affect the i.m. midazolam dose selected for premedication.

[Clinical study of AJ-007 (bupivacaine) in spinal anesthesia--investigation of clinical dosage of isobaric and hyperbaric formulations]

Spinal anesthesia with two types of 0.5% bupivacaine hydrochloride solution, isobaric AJ-007 I and hyperbalic AJ-007 H, was studied clinically in 106 surgical patients with collaboration of 7 university hospitals. The following results were obtained. 1) Successful analgesia with motor block on abdominal wall and legs could be induced by dosages of 2.0 ml, 3.0 ml and 4.0 ml of either of the two solutions. 2) With isobaric solutions, the duration of the block was prolonged dose dependently. Anesthetic levels tended to increase and onset times of the block tended to decrease, with increasing dosage. 3) Hyperbalic solutions tended to produce higher levels of the block more rapidly. However, the duration of the block seemed to be shorter than that achieved by isobaric solutions. 4) The incidence of hypotension and bradycardia was similar to that observed in ordinary clinical spinal anesthesia. In one young male, a high level (C 2) of anesthesia was achieved after administration of 4.0 ml of hyperbaric solution. This patient was managed uneventfully under general anesthesia during the surgery. These results indicate that these two solutions of 0.5% bupivacaine are useful for spinal anesthesia.

[Postoperative respiratory disturbance after anterior cervical fusion]

We examined 171 patients who had undergone anterior cervical fusion to determine the frequency and the causes of postoperative respiratory disturbance (PRD). Postoperative tracheal intubation was necessary in 11 patients (6.4%), but only 4 of them (2.3%) required reintubation due to PRD caused by surgical procedures. PRD has been reported to occur at various frequencies in previous studies, partly due to unsettled criteria of PRD, miscellaneous primary diseases, and heterogeneous surgical procedures. As C 3 was fused in the 4 patients with PRD, requiring reintubation, upper airway obstruction due to serious swelling of the soft tissue surrounding C 3 might be the factor leading to postoperative reintubation. One of the PRD patients who suffered from postoperative unilateral phrenic nerve palsy required controlled ventilation.

Molecular cloning of a cDNA encoding a pollen extracellular protein as a potential source of a pollen allergen in Brassica rapa

A polyclonal antiserum was raised against the extracellular pollen proteins of Brassica rapa and used for screening the expression cDNA libraries made from immature anthers. We obtained five groups of cDNA clones, including cDNAs similar to PCP1, thioredoxin, and lipid transfer protein (LTP). Recombinant protein of the cDNA clone showing sequence similarity to LTP was demonstrated to bind IgE of a patient allergic to Brassica pollen. The cDNA clone reported here, therefore, represents a novel pollen allergen of Brassica rapa.

Adenylyl cyclase is involved in desensitization and recovery of ATP-stimulated Cl- secretion in MDCK cells

We investigated the process of and recovery from desensitization of the P2 receptor-mediated stimulation of Cl- secretion in Madin-Darby canine kidney (MDCK) cell monolayers by assaying the response of short-circuit current (Isc). When the cells were exposed to repeated 3-min challenges of ATP or UTP interspersed with 5-min washes, the response of Isc desensitized rapidly followed by spontaneous recovery. The pattern of inhibition by various channel blockers or enzyme inhibitors revealed that both the initial and recovered responses of Isc have the same ionic and signaling mechanisms. The desensitization and recovery processes were confined to the membrane exposed to the repeated challenges. When added during the desensitized phase, 8-bromoadenosine 3',5'-cyclic monophosphate enhanced the ATP-stimulated Isc response, whereas it did not during the initial or recovered phases. ATP-induced increases of intracellular adenosine 3',5'-cyclic monophosphate showed similar desensitization and recovery in parallel with the changes in the responses of Isc. The desensitization process was attenuated by pretreatment with cholera toxin or pertussis toxin. Taken together, our results suggest that the adenylyl cyclase system plays a role in the desensitization and recovery mechanism of the ATP-stimulated Cl- secretion in MDCK cells.

[Propofol and sevoflurane--a comparison of anesthesia for laryngomicrosurgery]

Laryngomicrosurgery has some special characteristics. It is under much stress such as intubation and direct laryngoscopy during a short operation time. Therefore both adequate anesthesia and quick recovery are needed. Thirty three ASA physical status I patients for laryngomicrosurgery were randomly assigned to receive either anesthesia with propofol and small dose of fentanyl (Group P) or anesthesia with thiopental and sevoflurane (Group S). Group P was induced with propofol 2-3 mg.kg-1 and fentanyl 0.1 mg and maintained with propofol 6 mg.kg-1.h-1 (from 10 mg.kg-1.h-1 by 2 mg.kg-1.h-1 decrement in interval of 10 minutes). No intravenous analgesic was added. Group S was induced with thiopental 4 -5 mg.kg-1 and maintained with sevoflurane 2-3%. We compared emergence time and the state of recovery 5 minutes after extubation and 5 minutes after entering the recovery room. There was no episode of inadequate anesthetic state in both groups. The emergence time was significantly shorter in Group P than in Group S. The state of recovery was much better in Group P compared with Group S in both 5 minutes after extubation and 5 minutes after entering the recovery room. Therefore, anesthesia with propofol and small dose of fentanyl at induction is more adequate compared with anesthesia with sevoflurane in laryngomicrosurgery.

Enhanced metastasis of B16 melanoma cells by unexpected elevated expression of the metastasis-associated TI-241 (LRF-1-, Jun-Fos-related) gene treated with antisense oligonucleotide

B16-F10 is a B16 mouse melanoma subline that preferentially metastasizes to the lung following intravenous injection. Previously we isolated TI-241 (LRF-1 homologue related to Jun-Fos) gene that was expressed higher in the high metastatic clone B16-F10 than the low metastatic clone F1. Transfection of TI-241 into F1 converted it into a high-metastatic cell. We studied the effect of antisense oligonucleotide designed to reduce the expression of TI-241 in B16-F10 cells, and observed an unexpected increase in the TI-241 level. The increase in the expression was maximal at 30 h, then it decreased during further culture with or without TI-241 antisense oligonucleotide. This increased TI-241 expression by antisense oligonucleotide was also observed in B16-F1 cells whereas sense oligonucleotide did not affect the expression. B16-F10 cells cultured with TI-241 antisense oligonucleotide showed enhanced experimental metastatic potential to the mouse lungs compared with untreated B16-F10 and B16-F10 cultured with TI-241 sense oligonucleotide.

[Relationship between cardiac output and PETco2 as well as Paco2 during high-dose fentanyl anesthesia]

We investigated the relationship between cardiac output and PETCO2 as well as blood PCO2 in 10 patients undergoing cardiac surgery of long duration under high-dose fentanyl anesthesia. After anesthetic induction, the minute ventilation was kept constant at 10 ml.kg-1 x 10 cycles.min-1 and a pulmonary artery catheter was inserted. PETCO2, PaCO2 and cardiac index (CI) were measured simultaneously. PaCO2 was corrected for body temperature, and alveolar dead space-to-tidal volume ratio was calculated as VD/VTalv = (PaCO2-PETCO2)/PaCO2. After body, temperature became stabilized, the measurements were started and repeated every 10 to 20 minutes during the prebypass period. One hundred and eight sets of data were taken from 10 patients. PETCO2 correlated positively with CI. Similarly, PaCO2 correlated positively with CI, but VD/VTalv, did not correlate with CI. PETCO2 correlated closely and positively with PaCO2, but it correlated negatively and only marginally with VD/VTalv. When examined in individual patients, PaCO2 correlated positively with PETCO2 in all patients, while VD/VTalv correlated negatively with PETCO2 only in 3 patients. By multiple regression analysis, VD/VTalv change accounted for only 22.3 +/- 15.0% of PETCO2 change, while PACO2 or PaCO2 change accounted for 77.6 +/- 15.0% of PETCO2 change. Decreased CI was associated with decreased CO2 delivery from the tissue to the lung (DCO2) and PaCO2 decreased with decreasing DCO2. Decreased CI was also associated with decreased oxygen uptake (VO2), and PaCO2 decreased with decreasing VO2. A decrease in CI resulted in an increase in VA/Q, and PaCO2 decreased when VA/Q increased. PETCO2 decreased when cardiac output decreased. A decrease in PACO2 explained the decrease in PETCO2 better than an increase in VD/VT did. Decreased cardiac output might cause hypocapnia through decreased CO2 delivery to the lung, decreased CO2 production and/or increased ventilation-to-perfusion ratio.

Inhibition of pancreatic elastase by sulfated lipids in the intestinal mucosa

Sulfated lipids, cholesterol sulfate (CS) and I3SO3-GalCer, are commonly present in the epithelia of the digestive tracts of pigs, humans, rabbits, and rats. CS was the only sulfated lipid in the esophageal epithelia of these mammals, and I3SO3-GalCer, together with CS, was detected in the epithelia of the gastrointestinal tracts, at a concentration higher than 0.05 micromol per gram of dry weight. Although no sulfated lipids were present in the pancreatic duct, they were found in relatively high concentrations in the duodenal, jejunal, and ileal epithelia. To elucidate the functional significance of sulfated lipids in the digestive tract, we determined the effect of CS and I3SO3-GalCer on the activities of pancreatic and Pseudomonas aeruginosa elastases and found that both characteristically inhibited the pancreatic elastase but not the P. aeruginosa elastase. Desulfation of CS and I3SO3-GalCer abolished their inhibitory activity, and other membrane constituents including free fatty acids, phospholipids, and gangliosides failed to inhibit pancreatic elastase. In addition, steroid sulfates, such as dehydroepiandrosterone sulfate and pregnenolone sulfate, did not exhibit any inhibitory activity toward pancreatic elastase, indicating that the sulfate group and a suitable hydrophobic side chain are required in the inhibition of elastase. Inhibition of elastase by sulfated lipids occurred in a dose-dependent manner, and the molar ratios of CS and I3SO3-GalCer to elastase at which the enzyme activity was inhibited to 50% of the maximum level were 6:1 and 9:1, respectively. CS-treated elastase had the same Km and a lower Vmax compared with the untreated enzyme, and sulfated lipids were observed to bind tightly to the enzyme, suggesting irreversible inhibition. Thus, CS and I3SO3-GalCer in the digestive tracts of mammals were shown to function as epithelial inhibitors of pancreatic elastase.

In vitro changes in the transparency and pH of cerebrospinal fluid caused by adding midazolam

The effects of adding midazolam and bupivacaine to human cerebrospinal fluid in glass test tubes were examined by looking for changes in pH and a reduction in the transparency of the solution. Midazolam (n = 6), 0.25% bupivacaine (n = 6), 5 mg of midazolam in 6 mL of 0.25% bupivacaine (n = 6) and 5 mg of midazolam in 10 mL of saline (n = 6) were added to 1.5-mL samples (n = 24) of cerebrospinal fluid taken at the time spinal anaesthesia was begun. Transparency and pH were checked after each increment. Cerebrospinal pH was decreased to below 7.0 by adding more than 3 mg of midazolam, more than 1.9 mL of 0.25% bupivacaine or 1.3 mL of the mixture. Cerebrospinal transparency was decreased by adding more than 0.7 mg of midazolam, 1.1 mL of 0.25% bupivacaine or 0.6 mL of the mixture. Midazolam in saline neither decreased the pH below 7.0 nor reduced transparency. These results do not suggest that clinically useful doses of intrathecal or epidural midazolam are neurotoxic.