Recoverin: a calcium sensitive activator of retinal rod guanylate cyclase

Vertebrate retinal photoreceptors recover from photoexcitation-induced hydrolysis of guanosine 3', 5'-monophosphate (cyclic GMP) by resynthesizing cyclic GMP, which reopens cation channels that have been closed by light. Activation of guanylate cyclase by light-induced depletion of cytosolic calcium is a key event in this recovery process. This cyclase has now been shown to be regulated by a 23-kilodalton calcium binding protein. The protein is present in both rod and cone photoreceptors and was named recoverin because it promotes recovery of the dark state. The amino acid sequence of recoverin exhibits three potential calcium binding sites (EF hands). That recoverin binds calcium was confirmed with calcium-45 and by observing calcium-induced changes in its tryptophan fluorescence. Recoverin activated guanylate cyclase when free calcium was lowered from 450 to 40 nM, an effect that was blocked by an antibody to recoverin. Thus, guanylate cyclase in retinal rods is stimulated during recovery by the calcium-free form of recoverin. A comparison of recoverin with other calcium binding proteins reveals that it may represent, along with the protein visinin, a family of proteins that are regulated by submicromolar calcium concentrations.

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery. A randomised, double-blind, cross-over study with and without adrenaline

BACKGROUND

Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture.

METHODS

A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml.h-1 of bupivacaine 1 mg.ml-1, fentanyl 2 micrograms.ml-1, and adrenaline 2 micrograms.ml-1 were included. On the 1st and 2nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score.

RESULTS

The number of hypaesthetic dermatomal segments decreased (P < 0.001) and pain intensity at rest and when coughing increased (P < 0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15-20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng.ml-1 (P < 0.01), and there was more sedation during the period without adrenaline.

CONCLUSIONS

Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.

Methylprednisolone intravenously 1 day after surgery has sustained analgesic and opioid-sparing effects

BACKGROUND

In previous studies on glucocorticoids for postoperative pain, the test drug has been given perioperatively, usually before measurement of baseline pain. In order to evaluate the time course and magnitude of the analgesic effect of a glucocorticoid in well-established postoperative pain, we compared methylprednisolone with ketorolac and placebo, after assessment of baseline pain on the first postoperative day.

METHODS

This was a double-blind, single dose, randomized, parallel comparison of intravenous (i.v.) methylprednisolone 125 mg, ketorolac 30 mg as an active control, and placebo in 75 patients with moderate to severe pain 1 day after orthopaedic surgery. Outcome variables were pain intensity (0-100 VAS), pain relief (0-4 PAR) and rescue opioid consumption.

RESULTS

Methylprednisolone was not significantly different from ketorolac and gave significantly lower pain intensity from 1 h (0-6 h, P < 0.02), and more pain relief 2-6 h after test drugs (P < 0.05) compared with placebo. After 24 h, pain intensity was lower in both active drug groups compared with placebo (methylprednisolone, P < 0.0001; ketorolac, P < 0.007). Number needed to treat (NNT) calculated from patients having more than at least 50% of maximum obtainable total pain relief during the first 6 h (>50%maxTOTPAR(6 h)) was 3.6 for methylprednisolone and 3.1 for ketorolac. Number needed to treat calculated from the percentage reporting at least 50% pain relief for at least 4 h (>50%PAR(4 h)) was 2.8 for both groups. Opioid consumption was significantly reduced for 72 h after methylprednisolone compared with ketorolac (P < 0.02) and placebo (P < 0.003).

CONCLUSION

Methylprednisolone 125 mg i.v. 1 day after surgery gave similar early reduction of pain as i.v. ketorolac 30 mg. Less pain than placebo 24 h after methylprednisolone, and lower opioid consumption for 72 h compared with ketorolac and placebo indicate sustained analgesic effects of methylprednisolone.

The minimally effective concentration of adrenaline in a low-concentration thoracic epidural analgesic infusion of bupivacaine, fentanyl and adrenaline after major surgery. A randomized, double-blind, dose-finding study

BACKGROUND

We have documented that adrenaline 2.0 micro g.ml- 1 markedly improves relief of dynamic pain when added to a thoracic epidural analgesic infusion of bupivacaine 1 mg.ml- 1 and fentanyl 2 micro g.ml- 1. Concern about possible adverse effects on spinal cord blood flow, expressed by others, prompted us to find the lowest concentration of adrenaline needed to produce effective and reliable pain relief after major surgery.

METHODS

A prospective, randomized, double-blind, parallel group study was carried out in 36 patients after major thoracic or upper abdominal surgery. Patients with only mild pain when coughing during titrated thoracic epidural infusion of approximately 9 ml per hour of bupivacaine 1 mg.ml- 1, fentanyl 2 micro g.ml- 1, and adrenaline 2.0 micro g.ml- 1 were included. The study was conducted as a dose-finding study comparing three different adrenaline concentrations in the epidural mixture (0.5, 1.0, and 1.5 micro g.ml- 1) with each other and with adrenaline 2.0 micro g.ml- 1 in our standard epidural mixture. On the 1st postoperative day, the patients were randomly allocated into three equal groups of 12 patients each, and given a double-blind epidural infusion at the same rate, but with different adrenaline concentrations (0.5, 1.0, or 1.5 micro g.ml- 1). The effects were observed for 4 h or until pain when coughing became unacceptable in spite of rescue analgesia. Rescue analgesia consisted of up to two patient-controlled epidural bolus injections per hour (4 ml) and subsequent i.v. morphine, if necessary. All patients received rectal paracetamol 1 g, every 6th hour. Main outcome measures were pain intensity at rest and when coughing, evaluated by a visual analogue scale and an overall quality of pain relief score. The extent of sensory blockade was evaluated by determining dermatomal hypaesthesia to cold.

RESULTS

Pain intensity when coughing increased (P < 0.001) and the number of hypaesthetic dermatomal segments decreased (P < 0.002) when the concentration of adrenaline was reduced below 1.5 micro g.ml- 1 in the triple epidural mixture. This change started within two hours after reducing the concentration of adrenaline below 1.5 micro g.ml- 1. The differences in pain intensities at rest were less pronounced. After 4 h with adrenaline 0.5 or 1.0 micro g.ml- 1 pain intensity when coughing was unacceptable in spite of rescue analgesia. After restarting the standard epidural mixture with adrenaline 2.0 micro g.ml- 1, pain intensity was again reduced to mild pain when coughing and the sensory blockade was restored. Occurrence of pruritus increased with a decreasing adrenaline concentration.

CONCLUSIONS

Adrenaline in a dose-related manner improves the pain-relieving effect and sensory blockade and decreases the occurrence of pruritus of a low-concentration thoracic epidural analgesic infusion of bupivacaine 1 mg. ml- 1 and fentanyl 2 micro g.ml- 1 after major thoracic or upper abdominal surgery. The minimally effective concentration of adrenaline, when added to bupivacaine 1 mg.ml- 1 and fentanyl 2 micro g.ml- 1, to maintain relief of dynamic pain is approximately 1.5 micro g.ml- 1. The data clearly document that dynamic, cough-provoked pain is a more sensitive outcome measure for postoperative pain relief than pain at rest.

AIPL1, a protein implicated in Leber's congenital amaurosis, interacts with and aids in processing of farnesylated proteins

The most common form of blindness at birth, Leber's congenital amaurosis (LCA), is inherited in an autosomal recessive fashion. Mutations in six different retina-specific genes, including a recently discovered gene, AIPL1, have been linked to LCA in humans. To understand the molecular basis of LCA caused by aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) mutations, and to elucidate the normal function of AIPL1, we performed a yeast two-hybrid screen using AIPL1 as bait. The screen demonstrated that AIPL1 interacts specifically with farnesylated proteins. Mutations in AIPL1 linked to LCA compromise this activity. These findings suggest that the essential function of AIPL1 within photoreceptors requires interactions with farnesylated proteins. Analysis of isoprenylation in cultured human cells shows that AIPL1 enhances the processing of farnesylated proteins. Based on these findings, we propose that AIPL1 interacts with farnesylated proteins and plays an essential role in processing of farnesylated proteins in retina.

Epidural fentanyl markedly improves thoracic epidural analgesia in a low-dose infusion of bupivacaine, adrenaline and fentanyl. A randomized, double-blind crossover study with and without fentanyl

BACKGROUND

The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief, and side effects when removing fentanyl from an optimally titrated epidural infusion consisting of bupivacaine, fentanyl and adrenaline.

METHODS

A prospective, randomized, double-blind, crossover study was carried out in 20 patients after major upper abdominal surgery requiring a large longitudinal incision. Patients with only mild pain when coughing during thoracic epidural infusion of about 10 ml per hour of bupivacaine 1 mg x ml(-1), fentanyl 2 microg x ml(-1), and adrenaline 2 microg x ml(-1) were included. On the 1st and 2nd postoperative days, each patient was given a double-blind epidural infusion, at the same rate, with or without fentanyl. The effects were observed for 6 h or until pain when coughing became unacceptable in spite of rescue analgesia. Rescue analgesia consisted of up to two patient-controlled epidural bolus injections (4 ml) per hour and intravenous morphine if necessary.

RESULTS

Main outcome measures, i.e. pain intensity when coughing and at rest, increased (P<0.001) when fentanyl (19.2+/-5.2 microg x h(-1)) was omitted from the epidural infusion: after 6 h pain intensity when coughing had increased to unacceptable levels in spite of increased consumption of rescue bupivacaine and adrenaline (P<0.001). Within 15-20 min after restarting the triple epidural mixture with fentanyl, pain intensity was again reduced to mild pain when coughing.

CONCLUSIONS

A low dose of epidural fentanyl (20 microg x h(-1)) markedly improved the pain-relieving effect of bupivacaine and adrenaline infused epidurally at a thoracic level after major upper abdominal surgery. This dose of fentanyl is much too small to relieve severe dynamic pain when given systemically. Therefore, this study indirectly supports the view that a low-dose thoracic epidural infusion of fentanyl has a spinal analgesic site of action.

Stability of an epidural analgesic solution containing adrenaline, bupivacaine and fentanyl

BACKGROUND

A low dose solution of adrenaline 2 microg x ml(-1), fentanyl 2 microg x ml(-1) and bupivacaine 1 mg x ml(-1) has been reported to give superior pain control when used for epidural analgesia after major surgery. The present paper describes the compounding and chemical stability of this triple-component solution during storage and use.

METHODS

Sterile triple-component concentrates (11X) were diluted by the use of gas isolator technology to give ready-to-use infusion solutions. Eight solutions were analysed by reverse phase high-performance liquid chromatography (HPLC) methods, and assays were performed on 1, 45, 90 and 180 days after storage at 2-8 degrees C. After 180 days the solutions were subsequently stored at 22 degrees C for four days before they were reanalysed. HPLC quantification of adrenaline was also performed on samples from solutions given to 28 different patients.

RESULTS

The concentration of adrenaline and fentanyl decreased approximately 3.5% from 1 to 180 days at 4 degrees C and four days at 22 degrees C. The corresponding figure for bupivacaine was an apparent increase by 2.4% in concentration. No absorption to the polypropylene plastic bags of fentanyl and bupivacaine was detected. None of the 28 samples derived from used infusion bags contained less than 95% of the declared content of adrenaline.

CONCLUSIONS

The triple-component epidural analgesic solution remained stable during six months of cold storage, followed by four days of storage at room temperature. No significant degradation of adrenaline was observed in infusion solutions returned from the wards.

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Abstract P4-06-18: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Dunbier AK, Hazlett J, Niemi G, Kemp R. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-18.