Post-traumatic pain. Causes and therapeutic concepts

Each patient has the right of a dedicated pain therapy according to the state of the art. However an efficient pain therapy is not possible without knowing the cause of pain. In most posttraumatic pain situations peripheral nociceptors are activated and normal afferences are conducted via an intact nociceptive system. In contrast, neuropathic pain pain is caused by lesions of the nervous system itself. Mechanisms of central sensibilization and involvement of the sympathetic nervous system may lead to chronification of such pain conditions. The therapeutic regime of nociceptive and neuropathic pain is demonstrated by algorithms of treatment modalities. Apart from classic non-opioid analgesics, co-analgesics and opioids have an important status in chronic pain management as well. Prescription of these substances has to follow strictly defined standards of pain therapy. Blockades with local anaesthetics as mono-therapy of chronic pain are obsolete. In posttraumatic pain, however, a certain number of adjuvant blockades or infiltrations of triggerpoints may be helpful. The exeptional place of sympathetic blockades are in diagnosis and therapy of sympathetic maintained pain (SMP).

[Posttraumatic pain. Causes and therapeutic possibilities]

Each patient has the right of a dedicated pain therapy according to the state of the art. However an efficient pain therapy is not possible without knowing the cause of pain. In most posttraumatic pain situations peripheral nociceptors are activated and normal afferences are conducted via an intact nociceptive system. In contrast, neuropathic pain pain is caused by lesions of the nervous system itself. Mechanisms of central sensibilization and involvement of the sympathetic nervous system may lead to chronification of such pain conditions. The therapeutic regime of nociceptive and neuropathic pain is demonstrated by algorithms of treatment modalities. Apart from classic non-opioid analgesics, co-analgesics and opioids have an important status in chronic pain management as well. Prescription of these substances has to follow strictly defined standards of pain therapy. Blockades with local anaesthetics as mono-therapy of chronic pain are obsolete. In posttraumatic pain, however, a certain number of adjuvant blockades or infiltrations of triggerpoints may be helpful. The exceptional place of sympathetic blockades are in diagnosis and therapy of sympathetic maintained pain (SMP).

[Pharmacist's attitudes towards opioid prescription]

The prescription of strong opioids underlies a special legislation. The attitude of the pharmacists towards the long-term treatment with these analgesics and their opinion about the legislation is unknown in Germany and other European countries.

METHODS

A questionnaire was included in the Journal "Mitteilungsblatt der Apothekerkammer Westfalen-Lippe" and send to all 2300 pharmacists of the region Westfalen-Lippe in December 1997.

RESULTS

797 (35%) questionnaires were returned. In 82.4% of the pharmacies strong opioids are kept in stock. However, 140 pharmacists do not have opioids in stock due to too many different preparations or low prescription rate. 54% of the pharmacists warn their patients about endangering by the medication. The fear of psychological addiction (48.1%) is the main argument, also in patients with regular intake of the opioids (20.1%) and related to long acting opioids (10.8%). Nevertheless, 73% of the pharmacists advocate for a liberalization and 10.7% for an abolishment of the actual prescription laws.

DISCUSSION

The importance of the therapy with strong opioids is well accepted by the pharmacists. An ease of the prescription is demanded to improve the situation of the patients with chronic pain. However, the majority of the pharmacists warns the patients about this medication. Contact between prescribing doctors and pharmacists and an intensified education concerning the therapy with opioids are needed in addition to the education of the medical staff and the liberalization of the prescription laws.

Long-term effects of nerve blocks in chronic pain

Regional blockade techniques have been of crucial importance for decades in chronic pain therapy, but in recent years some developments have made a new definition of the status of invasive procedures necessary. The realization of chronic pain as a multifactorial process led to the establishment of an interdisciplinary approach to pain therapy, leaving blockades as only one step in a multimodal therapy. The mainstay of local anaesthetic blocks now is diagnostic and prognostic, but correct interpretation of the results is limited by different factors, and controlled studies on the diagnostic value of local anaesthetic blockade are lacking. In cancer pain, invasive procedures are necessary in only a few cases. Some neuroablative techniques can offer long-term pain reduction. In non-cancer pain, neurodestructive procedures should be reserved for some special indications (e.g. lumbar sympathetic neurolytic blocks in ischaemic diseases). In a great number of chronic pain conditions the sympathetic nervous system is involved or even has a central status. In the acute stage of these diseases sympathetic blockades can be the therapy of choice. There is no disease in which different invasive procedures are performed so frequently and so uncritically as in chronic low back pain. Up to now, however, all controlled studies of invasive procedures only demonstrated short-term effects and failed to prove long-term efficacy. Therefore any invasive technique should only be performed in well-selected patients over a defined period and with a limited number of blockades.

[Are tramadol enantiomers for postoperative pain therapy better suited than the racemate? A randomized, placebo- and morphine-controlled double blind study]

The goal of this prospective, randomised and double-blind pilot-study was to investigate the analgesic potency and the side-effects of tramadol enantiomers in clinical practice. One hundred patients recovering from orthopaedic surgery with a postoperative pain intensity of more than 50 on a visual analogue scale 0-100 mm (Table 1) were recruited for the study. They were treated in a randomised, double-blind way with a maximal dose of 150 mg i.v.(+)-,(-)-tramadol, racemate, or 15 mg i.v. morphine or saline in the placebo group (5 groups, 20 patients each). The primary criterium of efficacy was the number of responders defined as patients with a pain reduction of at least 20 on VAS after 40 min. In case of pain, responders were allowed to continue with the double-blind drug up to six hours. The non-responders were treated with morphine as the rescue analgesic. The secondary criterium was the incidence and severity of side-effects. Six patients terminated the study prematurely. One patient was excluded because of an allergic reaction to morphine, one patient could not be treated sufficiently with morphine, four were excluded because of protocol violations. There were 8 responders in the (+)-tramadol-,6 in the (-)-tramadol- and 6 in the racemate group, 16* (P < 0.05) in the morphine group, and 5 in the placebo group. Pain intensity after 40 min was reduced by 20 (p < 0.05), 17 (p < 0.05), 17 (p < 0.05), 36 (p < 0.01 vs placebo, p < 0.05 vs (+)-,(-)-tramadol, and racemate group) and 5 mm on the VAS in the (+)-, (-)-, (+/-)-tramadol-, morphine- and placebo-group, respectively. Thirty eight adverse events like nausea, vomiting, PCO2-increase, and urinary retention occurred in 20 patients, most frequently in the (+)-tramadol- and morphine group. Sedation was significantly less profound in the (-)-tramadol group 1-4 h postoperatively. There were no side-effect in the tramadol racemate group. The enantiomers were equal to the racemate in analgesic potency, but inferior by far to morphine. They showed more adverse events and, hence, can not be preferred to the racemate in postoperative pain therapy.

[A survey of physicians' knowledge about pain therapy with strong opioid analgesics]

INTRODUCTION

The WHO analgesic ladder, including the use of strong opioid analgesics for the treatment of cancer pain, is widely accepted. However, the use of opioids for the treatment of non-cancer pain is still controversial. This study investigates doctors' medical knowledge about basic aspects of pain management. Additionally, we determined whether the deficiencies in the treatment of patients suffering from pain are based on the rigorous national narcotic control system in Germany.

METHODS

We investigated the juridical and technical knowledge of physicians specializing in pain therapy by a questionnaire. During a postgraduate course the knowledge about pain therapy according to the WHO analgesic ladder and the beliefs concerning the narcotic regulations in Germany were evaluated. The survey participants were asked to rate their attitudes on a 10-point analogue scale (1=disagreement, 10=full agreement). The participants were also asked to indicate occupational criteria such as specialty, clinical practice area, and postgraduate years of practice. Descriptive statistics for the mean values were used.

RESULTS

One hundred and forty-three questionnaires were completed. The majority of participants worked at departments of anaesthesiology. Some 51.1% of the participants had no specific multiple-copy prescriptions for opioid analgesics. Only 72% of the physicians knew from which governmental institution they could order multiple-copy prescriptions. In general, more doctors would prescribe opioids by the use of normal forms. The controlled substance laws were seen as an impediment by the majority of participants, without relevant differences as to their years of practice. The regulations were regarded as ineffective protection against illegal use of opioids. Treatment of pain with strong opioid analgesics was seen as beneficial for the patients. The use of strong opioids for long-term treatment was recommended, and psychological addiction was regarded as non-existent.

CONCLUSION

Therapy with strong opioids is accepted practice, but significant deficits of legal and technical knowledge uphold the undertreatment of patients suffering from cancer and non-cancer pain. Patients with a legitimate need for pain relief by strong opioids are the unintended victims of tight narcotic regulations and deficits in medical education. An ease of regulatory conditions is mandatory to reduce the reluctance for prescribing opioids. On the other hand intensified continuous medical education is mandatory to reduce the undertreatment of patients with severe pain conditions.

Experiences with the prescription of opioids: a patient questionnaire

Forty-three German patients who had been treated with strong opioids were questioned about their experiences during therapy. The prescription of opioids was well accepted by most patients. Some, however, felt stigmatized by taking opioids. Fourteen patients (33%) were asked by their relatives, friends, or other patients about the special prescription form. Six patients (14%) had difficulties in redeeming the prescription at the pharmacy, seven patients (16%) were warned against taking the medication by the pharmacist, 21 patients observed that their general practitioner (GP) was mistrustful about the treatment, and 16 patients (37%) reported that the GP terminated the therapy. Despite the beneficial effect for the patient, opioid treatment started and supervised in a pain clinic is not always continued by the GP. In Germany, it may not be possible to administer opioid therapy outside of a specialized pain clinic. In those few cases in which an opioid therapy is successfully instituted, difficulties continue due to prejudices, insufficient education, and complicated prescription laws.

Long-term treatment of cancer pain with transdermal fentanyl

The long-term therapy of 51 patients using transdermal fentanyl was evaluated. The transdermal therapy was performed for 158 days (range, 15-855 days). The need for increasing dosages of transdermal fentanyl was caused by the progression of the underlying cancer disease (mean initial dose, 69.5 micrograms fentanyl/hr; mean final dose, 167.7 micrograms fentanyl/hr). The transdermal system was changed every third day. Application intervals had to be shortened in 23.5% of the patients. Pain reduction was good throughout the study. Severe side effects did not occur. Constipation and the need for laxatives occurred less frequently than with previously administered oral morphine. Skin tolerance of the transdermal system was good. The treatment of cancer pain with transdermal fentanyl can be performed as a long-term therapy and result in good pain relief. Considering its specific pharmacokinetic properties, it is an alternative medication on step III of the World Health Organization's guidelines for cancer pain management.

Antibody immobilization using heterobifunctional crosslinkers

Covalent attachment of functional proteins to a solid support is important for biosensors. One method employs thiol-terminal silanes and heterobifunctional crosslinkers such as N-succinimidyl 4-maleimidobutyrate (GMBS) to immobilize proteins through amino groups onto glass, silica, silicon or platinum surfaces. In this report, several heterobifunctional crosslinkers are compared to GMBS for their ability to immobilize active antibodies onto glass cover slips at a high density. Antibodies were immobilized at densities of 74-220 ng/cm2 with high levels of specific antigen binding. Carbohydrate-reactive crosslinkers were also compared to GMBS using a fiber optic biosensor to detect fluorescently-labeled antigen. At the concentrations tested, the antibodies immobilized with carbohydrate-reactive crosslinkers bound more antigen than GMBS immobilized antibodies as indicated by the fluorescence signal.

[Indications and limits of nerve block techniques]

Repetitive nerve blocks as a monotherapeutic treatment are loosing importance in the therapy of chronic pain. Such invasive methods for pain reduction are just one strategy in the interdisciplinary and multimodal planning of pain therapy. They are mostly used in special indications, e.g. reflex sympathetic dystrophy neurolysis in S3-S5 localized cancer pain. Premises for an invasive pain therapy are the patient's knowledge and agreement concerning this method. Furthermore, it is necessary for the physician to know the typical complications of the invasive treatment and to be able to manage them. It is recommended to document the pain course.

[Opioids and driving ability]

INTRODUCTION

Clinical observations of patients under oral opioid treatment suggest that the initially appearing central side effects such as sedation, dizziness or drowsiness decrease after a few weeks of treatment. However, it is still unclear whether long-term treatment with opioids impairs complex psychomotor functions such as driving a car.

METHODS

Twenty patients on stable dosages of oral opioids were examined using a driving simulator. The patients were regular car drivers and not older than 70 years. Additionally, every patient had to complete a questionnaire for mental condition and vigilance and the "d II" letter cancellation task. Control groups tested in the same way were: patients before an elective operation after taking benzodiazepines for sedation, volunteers after alcohol consumption (0.80 per thousand ), physicians on call with less than 4 h of sleep and healthy volunteers without any medication.

RESULTS

Some of the patients treated with opioids reacted as fast as medication-free volunteers. There were no significant differences between the reaction times of older patients (>50 years) receiving opioids in comparison to the group of older healthy volunteers. The same result was obtained in the letter cancellation task. No differences could be seen between medication-free volunteers and patients receiving opioids with regard to tasks of visual or motor control skills. The volunteers under influence of alcohol and the patients under benzodiazepines had a considerable decrease in performance.

CONCLUSIONS

Long-term therapy with opioids does not inevitably impair complex skills, but the decision to permit driving a car can only be made in the individual case.

PRACTICAL RECOMMENDATIONS

At the beginning of therapy with opioids the physician has to fulfil his duty to inform the patient of any possible dangers of treatment. From the medical point of view, driving must be prohibited until a stable opioid dosage is reached. Any changes in dosage (increase, reduction), change of the opioid and poor general condition independent of the opioid therapy must result in prohibition of car driving. Continuous control of the therapy with documentation is a duty of the physician. The written documentation should include the patients' physical and mental condition, side effects and the therapeutic result. From the medical point of view, driving can be possible when dosage treatment and general condition remain stable. In any case, the doctor has to remind the patient of the responsibility of critical self-examination. In doubt, special performance investigation should be taken into consideration.

[Anesthesia and intensive care management of severely burned children of Jehovah's Witnesses]

A 3.5-year-old girl suffered from a thermal injury affecting 37% of the body surface area. The parents, being Jehovah's witnesses, refused permission for their child to receive blood transfusions. As the haemoglobin level was only 7.5% and a necrectomy was planned, the patient was likely to need blood transfusions. Indications for transfusion were defined as clinical signs of hypoxia and/or cardiovascular instability. A judicial declaration was proposed. Hb decreased during the therapy. To stimulate the erythropoiesis erythropoietin and iron were administered. During the clinical course the anaemia worsened. First, a conservative treatment with polyvidoniodine ointment for tanning was started, to avoid an operation during the acute phase after the injury, as in this case it was thought a blood transfusion would definitely be necessary. On the 19th day after the injury a necrectomy of 10% of the body surface was necessary because of fever and leucocytosis not responding to antibiotics. The most likely cause of the symptoms was an infection of the burned area. Hb was 4.6 g/dl%. General anaesthesia was performed with midazolam, ketamine and vecuronium and mechanical ventilation. No blood transfusion was required during the operation. Vital signs were stable during the preoperative period, during anaesthesia and following the operation. There were no signs of tissue hypoxia. Peripheral oxygen saturation ranged between 98% and 100%, lactate and arterial blood gas samples were normal, and the child was awake and cooperative before and after anaesthesia. The lowest Hb was 3.3 g/dl on the 22th day after injury (3rd postoperative day). In this phase the patient was still playing and riding a tricycle. On the 45th day after injury the child was discharged home with Hb of 10.9 g/dl and reticulocytosis of 33%.

[Dangers and complications in pain therapy with epidural and intrathecal catheters.]

Pain therapy with epidural or intrathecal catheters is an invasive method. These techniques have specific indications in both acute and chronic pain therapy. However, complications can occur. Thus, the potential complications and the therapy necessary must be known.Drugs: Complications resulting from acute local anesthetic intoxication's are rare. High plasma levels during chronic therapy may lead to confusion. Respiratory depression can occur in opioid naive patients up to 12 (-24) h after injection. Adequate monitoring is a prerequisite for this therapy. After application of clonidine, hypotension is frequent in hypertonic and hypovolemic patients. Epidural or intrathecalcatheter placement can result in therapeutic failure, trauma by punction and inability to place the catheter. During chronic therapy, technical problems can occur, e.g., dislocation, occlusion. To exclude intrathecal and intravascular placement, application of a test dosage of a local anesthetic with adrenaline is recommended.Neurological complications can result in nerve root deficit or "simple" post-spinal headache, but cauda equina syndromes, paralyses, intracranial bleeding, sinus thrombosis and central neurological deficits have been reported. Skininfection at the insertion site of the catheter has been observed with an incidence of 1.9 to 7.7%. A spinal infection with neurological deficit is rare. Spinal infections are often associated with other diseases. Spinalhematomas are rare. Coagulation disorders and anticoagulants can lead to bleeding. Intravenous heparin should be avoided, because this is frequently associated with spinal bleeding. Therapy with cumarines is a contraindication for insertion of spinal catheters.Monitoring: During treatment with spinal catheters, adequate monitoring increases safety for the patients. Efficacy of the injections, puncture site and the neurological status should be documented daily. Neurological deficits must be diagnosed without losing time and adequate therapy must be initiated.

Transdermal fentanyl: a new step on the therapeutic ladder

The high efficacy, low molecular weight and high lipid solubility of fentanyl make it a suitable agent for transdermal administration. Effective plasma concentrations are maintained for up to 48-72 hours after application of a transdermal therapeutic system (TTS) fentanyl patch. In a multicentre study, slow-release morphine was replaced by TTS fentanyl according to a special calculation table (10 mg oral morphine corresponding to approximately 0.1 mg TTS fentanyl). Ninety-eight patients were included in the study. Due to protocol infringements, however, the switch from oral morphine to TTS fentanyl could be assessed for only 38 patients. The changeover at a ratio of 100:1 proved to be safe and effective and a good alternative therapy to conventional strong opioids. The majority of the patients wished to continue TTS fentanyl therapy at the end of the study period. Side effects were similar to those associated with other opioids. However, TTS fentanyl was associated with a distinct decrease in constipation and a significant reduction in the use of laxatives. Furthermore, there were some indications that compliance may be increased with TTS fentanyl. Special indications for chronic pain therapy using transdermal opioids include head and neck and gastro-intestinal tract cancer. In these cases, TTS fentanyl may be the final non-invasive form of analgesic therapy which allows the patient to maintain a normal lifestyle. TTS fentanyl thus represents a new alternative for therapy with strong opioids on step III of the World Health Organization analgesic ladder.

Plasma aluminum concentrations in long-term mechanically ventilated patients receiving stress ulcer prophylaxis with sucralfate

OBJECTIVES

To determine plasma aluminum concentrations and 24-hr urine aluminum excretion rate in long-term mechanically ventilated patients treated with 6 g of sucralfate daily for stress ulcer prophylaxis.

DESIGN

Prospective study in long-term mechanically ventilated critically ill patients.

SETTING

A surgical intensive care unit at a university hospital.

PATIENTS

Eleven long-term mechanically ventilated patients (multiple trauma [n = 8], abdominal surgery [n = 3]) were included in the study. The mean age of the patients was 57.2 +/- 10.8 yrs and the mean duration of treatment was 11.3 +/- 4.2 days.

INTERVENTIONS

1 g of sucralfate suspension intragastrically six times daily.

MEASUREMENTS AND MAIN RESULTS

Baseline plasma aluminum concentrations were determined at the beginning of the study. Patients received 1 g of sucralfate suspension given intragastrically six times daily via a nasogastric tube. Daily plasma aluminum concentration was measured 3 hrs after the morning dose of sucralfate. The urine aluminum excretion rate was determined from the 24-hr urine samples. Determinations of plasma and urine aluminum concentrations were carried out by flameless atomic absorption spectrophotometry. Renal function was compromised in eight patients (maximum plasma creatinine concentration 2.7 mg/dL [238.7 mumol/L]; normal value < 1.4 mg/dL [< 123.8 mumol/L]). Mean daily plasma aluminum concentration varied between 7.5 +/- 1.6 micrograms/L (278 +/- 59.3 nmol/L) and 21.1 +/- 7.1 micrograms/L (782 +/- 263.1 nmol/L) (normal value < 10 micrograms/L [< 371 nmol/L]). The 24-hr urine aluminum excretion rate varied between 25.7 +/- 18.1 and 53.4 +/- 87.2 micrograms/L (952.4 +/- 671 and 1979 +/- 3232 nmol/L) (normal value < 12.2 micrograms/L [< 452 nmol/L]). Aluminum accumulation did not occur in any of the patients.

CONCLUSIONS

The administration of 6 g of sucralfate daily in long-term mechanically ventilated surgical patients did not result in an increase in the plasma aluminum concentration. Sucralfate can be administered safely for a period of at least 2 wks, even in critically ill patients with impaired renal function.

[Does the mixture of bupivacaine and prilocaine as opposed to bupivacaine afford a clinical advantage in epidural anesthesia?]

Local anaesthetic mixtures are often used to shorten the onset of regional anaesthesia. However, the results of these mixtures of epidural anaesthesia (EDA) are controversial. Alkalinisation of bupivacaine shortens the onset of EDA. Since mixing prilocaine with bupivacaine results in a local anaesthetic mixture with a pH of 6.8, we investigated whether this mixture can shorten the onset of EDA compared to plain bupivacaine. METHOD. In a randomised, double-blind study, 60 patients received single-shot EDA with a standardised amount of local anaesthetic (1 ml/segment for 150 cm body height +0.1 ml/segment for each further 5 cm). Group A received plain bupivacaine 0.5%, group B bupivacaine 0.5% and prilocaine 2% in a 1:1 ratio. Sensory (loss of warm/cold and pinprick sensation) and motor blockade (modified Bromage score) were studied 5, 10, 15, 20, 30, and 40 min after injection of the local anaesthetic. RESULTS. There was no difference in the onset of sensory blockade: loss of warm/cold and pinprick sensation developed in the same manner in both groups. Ten minutes after injection all patients showed changes in the perception of warm and cold stimuli. In group A this ranged from T 8.1 +/- 2.14 to L 4.36 +/- 1.79 and in group B from T 8.8 +/- 2.0 to L 4.4 +/- 1.55. Forty minutes after injection loss of warm/cold sensation ranged from T 6.6 +/- 2.89 to L 5.4 +/- 1.42 in group B and from T 7.2 +/- 1.24 to L 5.7 +/- 0.88 in group A. Nearly the same results were obtained for the pinprick test. Motor blockade developed more rapidly and intensely in group B. At the end of the observation period there were still 5 patients without any motor blockade in group A, while all patients in group B showed signs of motor blockade. DISCUSSION. Shortening of the onset times has been observed when alkalinized local anaesthetic solutions with a pH above 7.0 are used for EDA. In the present study the mixture of prilocaine and bupivacaine did not shorten the onset of EDA, most likely because the pH of this mixture is only 6.8. In contrast to peripheral nerve blocks, mixtures of local anaesthetics for EDA do not offer a clinical advantage with respect to onset time compared to plain local anaesthetics.

[Fentanyl-TTS for postoperative pain therapy. A new alternative?]

Treatment of postoperative pain is often insufficient. It normally consists of systemic application of an analgesic drug or a regional technique of analgesia. Fentanyl-TTS may be a new approach for postoperative pain therapy. Fentanyl is incorporated into a transdermal system; after application to the skin continuous release of therapeutic doses is achieved for a period of 72 h. Serum peak levels are obtained 8-16 h after application; the serum half-life is about 16-21 h because of the dermal depot. Fentanyl-TTS was administered in several clinical studies for therapy of postoperative pain. The efficacy of this new form of application could be demonstrated. For the first 12 h the patients needed supplementary doses of analgesic drugs in the same range as the placebo groups because of the lag time of fentanyl-TTS. In the following 12 h the need for supplementary analgesics was significantly reduced. After removal of the patch, the need for analgesics was still reduced for 12 h. In 21 of 341 patients respiratory depression occurred under therapy with fentanyl-TTS; no respiratory depression was observed in the placebo groups. Thus, respiratory depression might occur in up to 9% of postoperative patients treated with fentanyl-TTS. Other adverse effects were nausea (62%), vomiting (26%), sedation (22%), urinary retention (11%), headache (5%), and dizziness (8%). Local reactions under the patch were erythema (39%) or pruritus (9%). These phenomena disappeared within a few hours. The pharmacokinetics of fentanyl-TTS have two major drawbacks: during the first 12-15 h the patients need supplementary analgesics, usually opioids.(ABSTRACT TRUNCATED AT 250 WORDS)

[A new positioning aid for administering axillary plexus anesthesia]

A "plexus-table" is introduced as a new help to place an arm for application of the axillary plexus block. A modified Maquet arm posturing device offers a sufficient big plate, which is adjustable in all planes. The plate is fixed closely to the operation table. A more comfortable placement of the patient's arm is possible, due to the reduction of the externally rotation of the shoulder. The new table can be adapted to patients with restrictions of the movements of the shoulder. For the anaesthetist this results in a good presentation of the axillary region.

Circadian rhythm of total protein synthesis in the cytoplasm and chloroplasts of Gonyaulax polyedra

Protein synthesis of Gonyaulax polyedra was analyzed by means of electron microscopic autoradiographs under constant conditions at different times of the 24-hr cycle. Circadian rhythmic changes in the synthesis rate of total protein were determined in the cytoplasm and chloroplasts of growing cells. Three independent series of experiments in constant light showed a maximum of grains per unit area during the 'subjective' dark phase (= phase that corresponds to the dark phase during a 12:12 hr LD cycle) in both compartments. Minimum and maximum grain number are different by a factor of 5-10. The maximum of total protein synthesis coincided with the maximum phase shift by cycloheximide pulses (1) suggesting protein species within the total pool involved in the mechanism of the circadian clock. A similar rhythm of lower amplitude was observed in the mitochondria, but this rhythm cannot with certainty be attributed to these organelles. In a slowly growing culture a rhythm of total protein synthesis was observed that showed a smaller amplitude and a different phasing.