Translational regulation of angiotensin II type 1A receptor. Role of upstream AUG triplets

The cDNA sequence of rat angiotensin II type 1A receptor (AT1AR) shows that AT1AR transcripts have AUG triplets in the 5'-leader region that may begin a short open reading frame encoding an 11-amino acid peptide. In this study, the mutational inactivation of the start codon of the short open reading frame in AT1AR-chloramphenicol acetyltransferase (CAT) reporter gene constructs resulted in a 2.6-fold increase in CAT activity, whereas CAT transcript levels were not affected. Furthermore, experiments with rat AT1AR cDNA-transfected Cos-7 cells revealed that mutagenesis of the upstream AUG increased the AT1AR protein up to 2.5-fold, although AT1AR transcript levels showed no changes. The synthetic peptide corresponding to the sequence of the short open reading frame significantly suppressed the amount of AT1AR product in the in vitro translation system. The inhibiting effect of the short open reading frame appears to operate at least in part at the level of translation initiation, because polysome analysis with transfected Cos-7 cells showed that mutagenesis of the upstream AUG resulted in a shift of AT1AR mRNA distribution from a smaller to larger fraction of polysomes. Taken together, these results show that the upstream AUG inhibits translational regulation, suggesting that the short open reading frame in the 5'-leader region of AT1AR transcripts has a certain role in the translation of AT1AR protein.

[Addition of fentanyl to epidural lidocaine raises the toe temperature]

In order to investigate effects of addition of fentanyl epidurally on the onset of sympathectomy from epidural lidocaine, we have measured the toe temperature of 29 healthy patients undergoing elective lower extremity or lower abdominal surgeries. The latency of onset of the toe temperature was significantly shorter in patients receiving both epidural lidocaine and fentanyl compared with those receiving epidural lidocaine alone (258 +/- 135 vs 398 +/- 184 sec, P < 0.05 [mean +/- SD]). Osmolarity and pH of the epidural solutions were similar between the two groups. These results suggest, but do not indicate, that sympathectomy from epidural lidocaine is accelerated by the addition of fentanyl.

Spinal anesthesia attenuates myocardial ischemia during coronary artery spasm induced by intraaortic methacholine in rats

Coronary artery spasm is not rare in patients with coronary artery disease, but the influence of regional anesthesia on spasm-induced myocardial ischemia is not known. We investigated the effects of spinal anesthesia on myocardial ischemia during coronary artery spasm in rats, and compared these with the effects of an alpha- and beta-adrenergic antagonist, and an alpha-adrenergic agonist. An intraaortic catheter was inserted via the right internal carotid artery so that the tip of the catheter was placed near the coronary ostium. An intrathecal catheter was placed at lumbar level. Coronary spasm was induced by the intraaortic injection of methacholine, and we identified the thresholds of myocardial ischemia, defined as the dose of methacholine that induced ST-segment elevation. Subsequently, the thresholds were determined after spinal anesthesia, and after the intraaortic injection of phentolamine and propranolol. The thresholds of myocardial ischemia increased significantly after intrathecal bupivacaine. In contrast, the threshold did not change after the injection of phentolamine. The thresholds increased significantly after the injection of propranolol. Methoxamine significantly decreased the threshold of ischemia. These results demonstrated that spinal anesthesia attenuated myocardial ischemia during methacholine-induced coronary spasm. This effect was equivalent to that of propranolol.

Characterization of glucocorticoid response element of rat angiotensin II type 1A receptor gene

The responsiveness of the rat angiotensin II type 1a and type 1b receptor (AT1a-R and AT1b-R) genes to glucocorticoid was examined in rat vascular smooth muscle cells (VSMCs) and the glucocorticoid response element (GRE) of the AT1a-R gene was characterized. Glucocorticoid induced an increase in AT1a-R mRNA levels, whereas AT1b-R mRNA levels were unaffected. The nuclear run-off assay indicated that the transcription of the AT1a-R gene, but not that of the AT1b-R gene, was increased by glucocorticoid. The mRNA stability of AT1a-R was unchanged by glucocorticoid. Promoter/chrolamphenicol acetyltransferase reporter analysis demonstrated that the 5'-flanking region of the AT1a-R gene was functional in rat VSMCs and established that the GRE motif between -770 to -756 could confer glucocorticoid responsiveness on the AT1a-R gene.

Combined use of glucagon and milrinone may not be preferable for severe propranolol poisoning in the canine model

In a previous study of propranolol poisoning, glucagon and milrinone significantly increased cardiac output, but the improvement caused by glucagon was almost entirely due to the chronotropic effect. This study investigates the combined effect of glucagon, in a dose not inducing tachycardia, and milrinone on beta-blocker poisoning. Following the administration of 10 mg/kg propranolol IV over ten minutes, dogs (N = 20) were divided into four treatment groups, group S (saline), group G (glucagon 2.5 micrograms/kg), group M (milrinone 100 micrograms/kg), and group G + M (glucagon 2.5 micrograms/kg plus milrinone 100 micrograms/kg). Hemodynamic parameters were observed over the next thirty minutes. Heart rate, cardiac output, and mean arterial pressure were decreased in all groups after the administration of propranolol. Heart rate, mean arterial pressure, cardiac output, and stroke volume recovered to the baseline values in group G + M. However, heart rate in group G + M showed a significant increase versus the other three groups. In a canine model of severe propranolol poisoning, the combined effect of glucagon 2.5 micrograms/kg and milrinone 100 micrograms/kg brought about a significant hemodynamic improvement, but it was accompanied by an excessive increase of heart rate. Combined therapy of milrinone and glucagon may not be preferable therapy in beta-blocker poisoning in the canine model.

Age-related decrease in toe-thumb temperature difference with lumbar epidural anaesthesia

With lumbar epidural anaesthesia, big toe skin temperature increases and is associated with a compensatory decrease of thumb temperature. The purpose of the present study was to examine whether thumb-big toe temperature differences were affected by age. Following the attachment of temperature probes at the digital pad of the right big toe and the right thumb, lumbar epidural anaesthesia at L2/3 was performed in 54 patients with 10 ml lidocaine 1.5%. Big toe and thumb skin temperatures were measured continuously and recorded every minute. Fifteen minutes after epidural injection, the toe temperature increased 6.3 +/- 2.1 degrees C (delta F) from the control value, 29.4 +/- 2.2 degrees C, and the thumb temperature decreased -1.5 +/- 1.0 degrees C (delta H) from the control value, 31.6 +/- 2.8 degrees C. Regression coefficient between delta T15 (toe-thumb skin temperature 15 min after epidural injection) and age was: Y = -0.7X + 8.95 (r = 0.35, P < 0.01; Y = delta T15, X = age). The ratio of delta H to delta F and age was expressed as: Y = 0.51X - 46.57 (r = 0.41, P < 0.01: Y = delta H/delta F, X = age). It is concluded that, in lumbar epidural anaesthesia, the decrease of the thumb skin temperature is reduced with aging.

[Fluctuation of injection pressure of syringe pumps; the effect of syringe volumes and speed settings]

We measured fluctuation of injection pressure by several types of commercially available syringe pumps in order to investigate the effect of syringe volumes (Terumo syringe) and speed settings on the irregularity of injection speeds. We recorded the injection pressure continuously with various speed settings, except that one of the pumps injected irregularly at the settings of 2 and 1 ml.h-1. With 50 ml syringes, only two of the six pumps injected precisely at all the speed settings. With the other four types, a steep increase in pressure was recorded at the speed setting of 1 ml.h-1. However irregular infusion was never observed by using a syringe of a high resistant type (TOP syringe). With 30 ml syringes, injection pressures fluctuated in most of the six syringe pumps at a speed lower than 5 ml.h-1. In conclusion, changes in injection pressures depend on types of syringes, syringe volumes and speed settings. We urge not to use a 30 ml syringe to infuse vasoactive drugs with syringe pumps.

Arteriovenous differences in PCO2 and cardiac output during CPR in the dog

Using 14 mongrel dogs, we investigated the correlation between arteriovenous differences of PCO2 (AVD-CO2) and cardiac output (CO) during CPR. Ventricular fibrillation was induced by an electrical current and the respirator was stopped for 5 min. Cardiopulmonary resuscitation (CPR) was performed during the next 10 min and CO was measured with simultaneous arterial and venous blood gas analysis. CO was measured 26 times during CPR. The animals were divided into two groups according to the values of CO during CPR: low-CO group (CO < 0.3 l/min) and high-CO group (CO > or = 0.3 l/min). AVD-CO2 in the low CO group was 39.8 +/- 5.7 mmHg and that of the high group was 27.4 +/- 14.8 mmHg (mean +/- S.D., P < 0.05). In conclusion, AVD-CO2 showed an inverse result with the degree of CO during CPR.

Toe skin temperature as a guide to epidural anaesthesia dosing

To determine the time for additional epidural anaesthesia, skin temperature of the big toe was evaluated in 50 patients undergoing mastectomy. Epidural catheters were placed at or near the T5-6 intervertebral space and 12 ml, lidocaine 1.5% with 1:200,000 epinephrine were injected. When the skin temperature, which had increased following epidural anaesthesia, decreased by 0.3 degrees C without an increase of systolic arterial blood pressure (ABP) of more than 20%, 8 ml lidocaine 1.5% were injected. If the skin temperature increased, the monitor was judged to have been useful. When ABP increased > 20% without a decrease of skin temperature, the monitor was judged not to have been useful. Monitoring of toe skin temperature was useful in 39 patients (78%) in estimating the time for the first additional dose of epidural anaesthetic. First, second and third intervals between injection were 96.5 +/- 21.0 (n = 39), 69.7 +/- 14.2 (n = 35) and 50.1 +/- 12.2 min (n = 7), respectively. We conclude that, when epidural puncture is performed at upper thoracic levels, toe skin temperature can be a useful monitor to judge the time for additional anaesthetic.

Milrinone versus glucagon: comparative hemodynamic effects in canine propranolol poisoning

Glucagon has been reported to be one of the most effective treatments for severe beta-blocker poisoning. Recently, amrinone was suggested as an alternative therapeutic choice for beta-blocker poisoning. Milrinone, a derivative of amrinone, acts independently of beta-adrenoceptors and increases cyclic AMP. Therefore milrinone may also be effective in the treatment of beta-blocker poisoning. In the present study, we compared the effect of glucagon and milrinone in treating severe beta-blocker poisoning. Following the administration of 10 mg/kg propranolol i.v. over 10 min, heart rate, cardiac output, mean arterial pressure, stroke volume, and end tidal CO2 were depressed, while central venous pressure, and pulmonary capillary wedge pressure increased significantly (p < 0.05). Following the administration of saline (Group S, N = 3), glucagon 20 micrograms/kg (Group G, N = 5), and milrinone 300 micrograms/kg (Group M, N = 5), hemodynamic parameters were observed for 30 min. In group M, mean arterial pressure, cardiac output and stroke volume recovered to their baseline values, while central venous pressure and pulmonary capillary wedge pressure decreased. Although there were no significant differences between groups G and M, the heart rate, central venous pressure and pulmonary capillary wedge pressure, mean arterial pressure and stroke volume did not return to baseline values in group G. Milrinone administration produced a significant hemodynamic improvement without increasing the heart rate in the canine model of severe heart failure caused by propranolol. In the glucagon treatment group, central venous pressure and pulmonary capillary wedge pressure improved less than the milrinone group. Although more data are needed before a clinical recommendation, milrinone might be an effective drug to treat beta-blocker poisoning.

Plasma alcohol concentrations after celiac plexus block in gastric and pancreatic cancer

OBJECTIVE

The objective of this study was to compare the plasma alcohol concentrations after celiac plexus block in different types of cancer. The authors studied the consecutive changes of plasma alcohol concentrations after celiac plexus block in a gastric cancer group (group 1, n = 6) and a pancreatic cancer group (group 2, n = 5).

METHOD

Celiac plexus block was performed with 10 ml of absolute ethyl alcohol. In all patients, operations had been performed 1.2-3.5 years before the block. Arterial blood was sampled at 0, 5, 10, 15, 30, 60, 120, 240, and 480 minutes after the block.

RESULTS

The average dose of absolute ethyl alcohol was 0.186 g/kg in group 1 and 0.182 g/kg in group 2. Plasma alcohol concentrations in group 1 were about four times greater than those of group 2 (p < 0.01). The mean maximum level was reached at 15 minutes after injection in group 1 (44.0 +/- 5.8 mg/dl) and at 30 minutes in group 2 (13.1 +/- 2.4 mg/dl).

CONCLUSION

Plasma alcohol concentrations after celiac plexus block showed different patterns according to the site of cancer and the type of operation performed.

End-tidal CO2 and plasma lactate level: a comparison of their use as parameters for evaluating successful CPR

Serial changes of end-tidal CO2 (ETCO2) and plasma lactate levels during CPR have been described as useful to investigate or evaluate the results of CPR. However, there have been no reports comparing these parameters in the same model. By inducing cardiopulmonary arrest (2-7 min) in 28 Wistar rats, ETCO2 and serum lactate levels were studied after and just before CPR, respectively. In the survived group (N = 16), ETCO2 was maintained in high levels (20.1-16.3 mmHg), however in the non-survived group (N = 12), ETCO2 showed an abrupt decline (6.0-2.0 mmHg). The lactate levels before CPR in two groups were significantly higher than those of control levels, however there was no significant difference just before the CPR between the two groups. ETCO2 during CPR is a useful indicator for determining the successful application of CPR. However, serum lactate levels sampled just before the onset of CPR did not prove to be a useful indicator of successful CPR in rats.

Residual left ventricular pump function after acute myocardial infarction in NIDDM patients

OBJECTIVE

Left ventricular remodeling occurs immediately after MI, involving structural changes in noninfarcted segment. However, the residual left ventricular pump function in NIDDM patients after acute MI has not been clarified. The purpose of this study was to evaluate the difference in the process of left ventricular remodeling between NIDDM and nondiabetic patients.

RESEARCH DESIGN AND METHODS

Left ventricular regional EF images obtained by radionuclide angiography were investigated in 20 NIDDM and 29 nondiabetic patients the 3rd wk after acute MI.

RESULTS

Regional EF of the noninfarcted area and P/V had a significant hyperbolic relation with left ventricular EDV in both groups of patients. Despite no difference in the extent of myocardial necrosis and the number of coronary vessels diseased between NIDDM and nondiabetic patients, regional EF of the noninfarcted area and P/V were significantly lower when left ventricular EDV increased in NIDDM patients compared with nondiabetic patients.

CONCLUSIONS

Pathogenetic changes of the residual myocardium associated with NIDDM may adversely influence the process of left ventricular remodeling after MI, especially in patients with increased left ventricular EDV.

Arteriovenous differences of blood alcohol concentrations after celiac plexus block

After a celiac plexus block with ethyl alcohol, patients sometimes complain of symptoms of alcohol intoxication. We studied the consecutive changes of arterial and venous blood alcohol concentrations in 11 patients and investigated whether an arteriovenous difference exists. We performed a celiac plexus block with 10 ml absolute ethyl alcohol. The sampling sites were radial artery and internal jugular vein. Blood samples were collected at 0, 5, 10, 15, 30, 60, 120, 240 and 480 minutes after the block. The maximum level was reached 15 minutes after injection in both arterial and venous blood, 29.9 +/- 19.4 and 27.7 +/- 21.8 mg/dl (means +/- SD), respectively. Arteriovenous differences were observed 5 and 10 minutes after ethyl alcohol injection (p less than 0.01). There was a significant negative correlation between the ratio of arteriovenous differences to venous sampling and the time elapsed after the block (r = 0.41, p less than 0.01).

Left ventricular function in myocardial infarction. Predictive value during negative low-level exercise three weeks postinfarction

To evaluate whether the response of left ventricular pump function during low-level exercise in the early postinfarction period can anticipate its change during the first year after acute myocardial infarction (MI), global and regional ejection fractions (EF) were investigated using radionuclide angiography in 52 consecutive patients with negative predischarge exercise test. The changes in left ventricular EF and regional EF of the noninfarcted area during the early exercise test had a good linear relation with the changes during the first year after MI (r = 0.86, p less than 0.001 and r = 0.81, p less than 0.001, respectively). Our results indicate that the mobilization of the Frank-Starling mechanism and myocardial contractility were the important factors related to the change of left ventricular EF, and that the changes of left ventricular EF during exercise in the patient with a negative predischarge exercise test can predict the direction of change (concordant rise or fall) during the first year after MI.

Long-term survival and complications after composite graft replacement for ascending aortic aneurysm associated with aortic regurgitation

The Bentall operation was performed in 44 patients between March 1972 and December 1988. Twenty patients had stigmata of Marfan's syndrome, and 15 had aortic dissection. All showed annuloaortic ectasia. Follow-up ranged from 1 to 16 years (mean, 5.8 years). There were six early deaths (14%) and seven late deaths (16%), with actuarial survival at 10 years of 65 +/- 8%. The late deaths were mostly related to aneurysms occurring in the remainder of the aorta. No patient has undergone reoperation related to the composite graft, but six patients required seven subsequent operations on the remaining aorta. The actuarial probability of freedom from late death and subsequent operation at 8 years was 64 +/- 9% for the operative survivors, but it was 44 +/- 17% for the patients with aortic dissection and 37 +/- 19% for those with Marfan's syndrome. Postoperative angiography performed 3-168 months (mean, 42 months) postoperatively in 23 nonselective patients demonstrated recurrent true aneurysms at both or one of the coronary ostia (seven), persistent dissection distal to the distal aortic anastomosis (five), pseudoaneurysm at the left coronary ostium (one), pseudoaneurysm due to a small leak at the proximal aortic anastomosis (one), and partial dehiscence of the distal aortic suture line (one). Composite graft replacement carries a potential risk of various late complications. Our data support the concept that earlier detection and aggressive treatment of the late complications occurring in the remainder of the diseased aorta is necessary to improve long-term survival after the Bentall operation.

Pulmonary oedema after airway obstruction due to bilateral vocal cord paralysis

We report a case of pulmonary oedema which developed after airway obstruction due to bilateral vocal cord paralysis. The patient was a 52-yr-old woman undergoing craniotomy for an acoustic neuroma. Anaesthesia was uneventful. Spontaneous ventilation resumed after reversal of neuromuscular blockade. Following extubation she showed signs of airway obstruction and dyspnoea. The trachea was reintubated but she became hypoxic, PaO2-36 mmHg, produced pink frothy secretions and the x-ray was typical of pulmonary oedema. The oedema cleared within 24 hr. Tracheostomy was performed one week later as the cords were still fixed, but the latter had recovered by three months and the tracheostomy was closed. The cause of the cord paralysis is unknown but probably was a result of surgical trauma to the brain stem.

[Hemodynamic effects of lung inflation during bilateral and single lung ventilation--a clinical investigation]

Hemodynamic changes during positive airway pressure ventilation is well known. To compare changes of hemodynamic variables during one-lung inflation with those during two-lung inflation, we studied the effects of lung inflation on hemodynamic changes in 15 anesthetized patients who were intubated endobronchially. When the airway pressure was increased from 0 cmH2O to 10, 20, 30 cmH2O, systolic pressure decreased gradually and central venous pressure increased during both two-lung and one-lung inflations (P less than 0.05). During one-lung inflation, the decrease in arterial pressure relative to apneic arterial pressure was significantly less than those during two-lung inflation at each level of airway pressure (P less than 0.05). During one-lung inflation, central venous pressure which was higher relative to apneic central venous pressure, and was less than that during two-lung inflation at 30 cmH2O (P less than 0.05). Heart rate was unchanged during both two and one-lung inflations compared with apneic heart rate. We conclude that during one-lung inflation, systolic pressure and central venous pressure are influenced less by the increased airway pressure than during two-lung inflation. The results indicate that during one lung ventilation, lungs inflated with clinically accepted levels of airway pressure do not depress the systemic circulation, but when the airway pressure during one-lung inflation (like a leak test) exceeded over 30 cmH2O, a significant depression of the systemic circulation occurs.

[A case report of traumatic transection of the aortic arch]

A 16-year-old male, who sustained a blunt chest trauma in a traffic accident, was brought into the emergency room in an unconscious state, with an initial systolic blood pressure of 80 mmHg. He was found to have multiple fractures and a flail chest. The initial roentgenogram of the chest showed widening of the mediastinum. An emergency aortogram demonstrated intimal flap and aneurysmal dilatation of the aortic arch. Because of a coexisting severe contusion of the lung, operation was postponed until 15 days after admission. He was successfully treated by direct repair under profound hypothermia and circulatory arrest, which was induced by surface cooling in combination with ECC. Postoperatively he did well and 23 days after the operation, surgical repair of femoral and humeral fractures was performed by orthopedists.