Endogenous serotonin in human blood platelets: factors that may influence reference values

The endogenous content of serotonin in human platelets has been used in many clinical studies to indicate platelet activation. A decrease in platelet serotonin compared with controls has been regarded as an indicator of platelet activation. However, the results published are difficult to compare, because of huge variations in endogenous serotonin between control groups in different investigations. This is likely to be because of lack of standardization. Several factors that influence the endogenous platelet serotonin content were studied in more than 200 blood donors. The most important factor was the total g force of the centrifugation used to isolate platelets. Also the age and sex of platelet donors, number of platelets in platelet-rich plasma, and mean platelet volume influenced normal serotonin values. Using a standardized centrifugation procedure (2700 g min) the mean endogenous serotonin was 2.80 nmol/10(9) platelets in young women and 2.58 in elderly women, and 2.67 in young men and 2.30 in elderly men. The differences both for age and sex were statistically significant. Endogenous platelet serotonin shows intrapersonal stability over time, since endogenous platelet serotonin did not change on repeated venepuncture for 9 weeks. Factors such as age, sex and isolation procedure must therefore be considered when endogenous platelet serotonin are studied in relation to disease and treatment.

Does β2-adrenergic stimulation attenuate fluid extravasation during hypothermic cardiopulmonary bypass? An experimental study in pigs

OBJECTIVES

Hypothermic cardiopulmonary bypass (CPB) is associated with increased fluid filtration, edema formation and, occasionally, organ dysfunction. Cold-induced reduction in endothelial barrier function may play a role. β(2)-adrenergic activation elevates cellular cyclic adenosine monophosphate (cAMP) which maintains endothelial barrier properties. In this study, we tested whether β-adrenergic stimulation could influence the increase in fluid extravasation observed during hypothermic CPB.

MATERIALS AND METHODS

Fourteen pigs randomly received terbutaline infusion (T-group) (n=7) or a control infusion (C-group) (n=7). All animals were given 60 min of normothermic CPB, followed by 90 min of hypothermic CPB. Fluid input and losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum proteins and total tissue water content were measured and the fluid extravasation rates (FER) calculated.

STATISTICS

by SPSS. Values presented as mean ± SD. Repeated measure analysis of variance was performed and a t-test used when appropriate.

RESULTS

The commencement of normothermic CPB resulted in a 20% hemodilution, with an abrupt increase in fluid requirements during the first 10 min. FER increased from 0.18 (0.06) pre-bypass to 0.78 (0.27) ml/kg/min (T-group) (p=0.002) and from 0.16 (0.05) to 0.93 (0.26) ml/kg/min (C-group) (p<0.001) with no between-group differences. Thereafter, FER stabilized at a level of 0.32 (0.13) and 0.27 (0.14) ml/kg/min in the T-group and C-group, respectively. After the start of cooling, FER increased in the T-group to 0.55 (0.12) ml/kg/min (P=0.046) and in the C-group to 0.54 (0.13) ml/kg/min (P=0.006), with no between-group differences (P=0.738).

CONCLUSION

In the present experimental study, we were unable to demonstrate any clinically relevant modulating effect of terbutaline on fluid extravasation during hypothermic cardiopulmonary bypass.

Infusion of hypertonic saline/starch during cardiopulmonary bypass reduces fluid overload and may impact cardiac function

OBJECTIVE

Peri-operative fluid accumulation resulting in myocardial and pulmonary tissue edema is one possible mechanism behind post-operative cardiopulmonary dysfunction. This study aimed to confirm an improvement of cardiopulmonary function by reducing fluid loading during an open-heart surgery.

MATERIALS AND METHODS

Forty-nine elective CABG patients were randomized to an intraoperative infusion of hypertonic saline/hydroxyethyl starch (HSH group) or Ringer's solution (CT group). Both groups received 1 ml/kg/h of the study solution for 4 h after baseline values were obtained (PICCO transpulmonary thermodilution technique). Net fluid balance (NFB), hemodynamic and laboratory parameters were measured.

RESULTS

NFB was four times higher in the CT group compared with the HSH group during the first 6 h post-operatively. The total fluid gain until the next morning was lower in the HSH group, 2993.9 (938.6) ml, compared with the CT group, 4298.7 (1059.3) ml (P<0.001). Normalized values (i.e., %-changes from the baseline) of the cardiac index and the global end diastolic volume index increased post-operatively in both groups. Both parameters were significantly higher at 6 h in the HSH group compared with CT group (P=0.002 and 0.005, respectively). Normalized values of the intrathoracic blood volume index were lower in the HSH group at 6 h post-operatively when compared with the CT group. The PaO(2)/FiO(2) ratio decreased similarly in both groups early post-operatively, but recovery tended to be more rapid in the HSH group. Although serum-sodium and serum-chloride levels were significantly higher in the HSH group, the acid-base parameters remained similar and within the normal range.

CONCLUSIONS

An intraoperative infusion of HSH during cardiac surgery contributes to reduced fluid loading and an improvement in the post-operative cardiac performance. No adverse effects of the HSH infusion were observed.

A hyperosmolar-colloidal additive to the CPB-priming solution reduces fluid load and fluid extravasation during tepid CPB

Cardiopulmonary bypass(CPB) is associated with fluid overload. We hypothesized that fluid gain during CPB could be reduced by substituting parts of a crystalloid prime with 7.2% hypertonic saline and 6% poly(O-2-hydroxyethyl) starch solution (HyperHaes®). 14 animals were randomized to a control group (Group C) or to Group H. CPB-prime in Group C was Ringer’s solution. In group H, 4 ml/kg of Ringer’s solution was replaced by the hypertonic saline / hydroxyethyl starch solution. After 60 min stabilization, CPB was initiated and continued for 120 min. All animals were allowed drifting of normal temperature (39.0°C) to about 35.0°C. Fluid was added to the CPB circuit as needed to maintain a 300-ml level in the venous reservoir. Blood chemistry, hemodynamic parameters, fluid balance, plasma volume, fluid extravasation rate (FER), tissue water content and acid-base parameters were measured/calculated. Total fluid need during 120 min CPB was reduced by 60% when hypertonic saline/hydroxyethyl starch solution was added to the CPB prime (p<0.01). The reduction was related to a lowered FER. The effect was most pronounced during the first 30 min on CPB, with 0.6 (0.43) (Group H) compared with 1.5 (0.40) ml/kg/min (Group C) (p<0.01). Hemodynamics and laboratory parameters were similar in both groups. Serum concentrations of sodium and chloride increased to maximum levels of 148 (1.5) and 112 (1.6) mmol/l in Group H. To conclude: addition of 7.2% hypertonic saline and 6% poly(O-2-hydroxyethyl) starch solution to crystalloid CPB prime reduces fluid needs and FER during tepid CPB.

Benzalkonium chloride interferes with energy production, secretion and morphology in human blood platelets

Benzalkonium chloride (BC) is a bactericidal compound used as a topical antiseptic and as a preservative in various products for local treatment, e.g., eye and nose drops. BC is toxic to human cells, including those of the respiratory mucosa. Few studies have, however, focused on what cellular functions BC interferes with. The effects of BC were studied on washed human blood platelets in vitro . Cellular energy production as well as secretion were studied. Incubation of platelets with BC resulted in rapid swelling and toxic morphological changes. After incubation with BC oxidation of [1-14C] palmitate was inhibited, and both lactate dehydrogenase and endogenous serotonin were spontaneously released. Thrombin-induced secretion of serotonin was strongly reduced after BC exposure. Histological changes with increased size, spherical form, decreased numbers of pseudopodia, loss of an intact continuous tubulus system and reduced number of granules were found by scanning and transmission electron microscopy. It is concluded that the toxic effects of BC are because of interference with membrane function and energy production.

Reduced fluid gain during cardiopulmonary bypass in piglets using a continuous infusion of a hyperosmolar/hyperoncotic solution

BACKGROUND

The aim of this study was to evaluate how a continuous infusion of a hyperosmolar/hyperoncotic solution influences fluid shifts and intracranial pressure during cardiopulmonary bypass in piglets.

METHODS

Fourteen animals, randomized to the control (CT) group or the hypertonic saline/hydroxyethyl starch (HyperHaes) (HSH) group, received acetated Ringer's solution as prime and supplemental fluid. The HSH group received, in addition, HyperHaes 1 ml/kg/h. After 1 h of normothermic cardiopulmonary bypass, hypothermic cardiopulmonary bypass (28 degrees C) was initiated and continued for 90 min. Fluid balance, plasma volume, tissue water content, acid-base parameters and intracranial pressure were recorded, and protein masses and fluid extravasation rates were calculated.

RESULTS

At the start of normothermic cardiopulmonary bypass, the fluid extravasation rates (ml/kg/min) increased from 0.19 (0.06) to 1.57 (0.71) and 0.19 (0.09) to 0.82 (0.14) in the CT and HSH groups, respectively, with no between-group differences (P = 0.081) During hypothermic cardiopulmonary bypass, the fluid extravasation rates (ml/kg/min) increased from 0.19 (0.14) to 0.51 (0.10) (P < 0.01) and 0.15 (0.08) to 0.33 (0.08) (P < 0.05), respectively, with significantly lower extravasation rates in the HSH group (P < 0.01). In the HSH group, the total fluid gain during cardiopulmonary bypass decreased by about 50% (P < 0.05) and the tissue water content was significantly lower in the left and right heart as well as in the lungs. The intracranial pressure remained stable in the HSH group, but increased in the CT group.

CONCLUSIONS

A continuous infusion of HSH (HyperHaes) during cardiopulmonary bypass reduced the fluid extravasation rate and the total fluid gain during bypass. No electrolyte or acid-base disturbances were present. The intracranial pressure remained stable in the HSH group.

Low arterial pressure during cardiopulmonary bypass in piglets does not decrease fluid leakage

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with increased fluid filtration occasionally leading to post-operative organ dysfunction. One of the factors determining fluid filtration is the capillary hydrostatic pressure which depends on arterial pressure, venous pressure and pre- to post-capillary resistance ratio. The purpose of this study was to assess whether lowering of the mean arterial pressure and/or the central venous pressure could reduce fluid extravasation during normothermic and hypothermic CPB.

METHODS

Seven piglets were given nitroprusside to a mean arterial pressure of 35-40 mmHg during 60 min of normothermic and 90 min of hypothermic CPB (LP group). They were compared with a control group (C group, n = 7) without blood pressure interventions. Blood chemistry, net fluid balance, plasma volume, colloid osmotic pressure in plasma and interstitial fluid, intravascular protein masses, fluid extravasation rate and total tissue water content were measured or calculated.

RESULTS

Mean arterial pressure was significantly lower in the LP group than in the C group during CPB. Plasma volume tended to increase in the LP group (P > 0.05), but remained essentially unchanged in the C group. Net fluid balance in the LP group was more positive than in the C group 30 min after CPB start [1.02 (0.15) vs. 0.56 (0.13) ml/kg/min (Mean (SEM) P < 0.05)]. Fluid extravasation rate tended to be higher in the LP group and total tissue water content of the gastrointestinal tract, left myocardium and skin was significantly elevated compared with the C group.

CONCLUSION

During CPB, lowering of the mean arterial pressure using nitroprusside did not reduce fluid extravasation. On the contrary, the data may implicate an increase in edema formation during low pressure CPB.

Fluid shift is moderate and short-lived during acute crystalloid hemodilution and normothermic cardiopulmonary bypass in piglets

BACKGROUND

Crystalloids are commonly used as priming solutions during cardiopulmonary bypass (CPB). Consequently, hemodilution is a regular occurrence at the start of a CPB. This study describes the time-course variations of hemodynamic parameters, plasma volume (PV) and fluid exchange following crystalloid hemodilution at start of normothermic CPB.

METHODS

Forty-five anesthetized piglets were given 60-min normothermic CPB. Ringer's solution was used as priming solution and maintenance fluid. Fluid input/losses, PV, colloid osmotic pressures (plasma/interstitium), hematocrit, and s-proteins were measured, and fluid extravasation rates (FER) and intravascular protein-masses calculated.

RESULTS

Start of CPB resulted in a 25-30% hemodilution. To keep the fluid level of the CPB-reservoir constant after start of bypass, fluid addition [2.08 +/- 0.36 (mean +/- SEM) ml kg(-1) min(-1)] was necessary during the first 5 min. Thereafter the fluid needs to be leveled off [0.17 +/- 0.03 ml kg(-1) min(-1) (10-60 min), P < 0.001]. Fluid extravasation rate increased immediately following hemodilution from a baseline value of 0.08 +/- 0.01 to 1.75 +/- 0.34 ml kg(-1) min(-1) with a delayed decrease compared to fluid additions, to reach a 'steady-state' level of 0.22 +/- 0.03 ml kg(-1) min(-1) after 30 min (P < 0.001). Differences in time-course variations between fluid added and fluid extravasated were accompanied by changes in PV and mean arterial pressure. The colloid osmotic gradient decreased about 50% throughout the study and could partly explain the increased FER.

CONCLUSION

Acute crystalloid hemodilution contributes to fluid overload during normothermic CPB. The resulting increase in fluid extravasation is, however, moderate, short-lived and levels off to baseline values within 30 min.

Can the use of methylprednisolone, vitamin C, or α-trinositol prevent cold-induced fluid extravasation during cardiopulmonary bypass in piglets?

OBJECTIVE

Hypothermic cardiopulmonary bypass is associated with capillary fluid leakage, resulting in edema and occasionally organ dysfunction. Systemic inflammatory activation is considered responsible. In some studies methylprednisolone has reduced the weight gain during cardiopulmonary bypass. Vitamin C and alpha-trinositol have been demonstrated to reduce the microvascular fluid and protein leakage in thermal injuries. We therefore tested these three agents for the reduction of cold-induced fluid extravasation during cardiopulmonary bypass.

METHODS

A total of 28 piglets were randomly assigned to four groups of 7 each: control group, high-dose vitamin C group, methylprednisolone group, and alpha-trinositol-group. After 1 hour of normothermic cardiopulmonary bypass, hypothermic cardiopulmonary bypass was initiated in all animals and continued to 90 minutes. The fluid level in the extracorporeal circuit reservoir was kept constant at the 400-mL level and used as a fluid gauge. Fluid needs, plasma volume, changes in colloid osmotic pressure in plasma and interstitial fluid, hematocrit, and total water contents in different tissues were recorded, and the protein masses and the fluid extravasation rate were calculated.

RESULTS

Hemodilution was about 25% after start of normothermic cardiopulmonary bypass. Cooling did not cause any further changes in hemodilution. During steady-state normothermic cardiopulmonary bypass, the fluid need in all groups was about 0.10 mL/(kg.min), with a 9-fold increase during the first 30 minutes of cooling (P <.001). This increased fluid need was due mainly to increased fluid extravasation from the intravascular to the interstitial space at a mean rate of 0.6 mL/(kg.min) (range 0.5-0.7 mL/[kg.min]; P <.01) and was reflected by increased total water content in most tissues in all groups. The albumin and protein masses remained constant in all groups throughout the study.

CONCLUSION

Pretreatment with methylprednisolone, vitamin C, or alpha-trinositol was unable to prevent the increased fluid extravasation rate during hypothermic cardiopulmonary bypass. These findings, together with the stability of the protein masses throughout the study, support the presence of a noninflammatory mechanism behind the cold-induced fluid leakage seen during cardiopulmonary bypass.

Immediate control of life-threatening digoxin intoxication in a child by use of digoxin-specific antibody fragments (Fab)

Digoxin-immune antibody fragments (Fab) for treatment of digitalis intoxication was introduced in 1976. Many reports have been published concerning this therapy for children, but few have focused on its immediate reversal of cardiac as well as extracardiac life-threatening manifestations of digoxin toxicity. We present a case of life-threatening digitalis intoxication in a child with postoperative renal insufficiency, after a Sennings procedure for transposition of the great arteries. Digoxin administration according to the nationally recommended dosage and intervals unexpectedly resulted in serum levels in the toxic range. Severe cardiac arrhythmias, haemodynamic instability and a rapid-increasing serum potassium level resulted. This report demonstrates how administration of Fab according to the manufacturer's dosage recommendation reversed the tachyarrhythmia immediately and re-established a normal level of serum potassium within minutes.

Fluid extravasation during cardiopulmonary bypass in piglets--effects of hypothermia and different cooling protocols

BACKGROUND

Hypothermic cardiopulmonary bypass (CPB) is associated with capillary fluid leak and edema generation which may be secondary to hemodilution, inflammation and hypothermia. We evaluated how hypothermia and different cooling strategies influenced the fluid extravasation rate during CPB.

METHODS

Fourteen piglets were given 60 min normothermic CPB, followed by randomization to two groups: 1: rapid cooling (RC-group) ( approximately 15 min to 28 degrees C); 2: slow cooling (SC-group) ( approximately 60 min to 28 degrees C). Ringer's solution was used as CPB prime and for fluid supplementation. Fluid input/losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum-proteins and total tissue water (TTW) were measured and fluid extravasation rates calculated.

RESULTS

Start of normothermic CPB resulted in a 25% hemodilution. During the first 5-10 min the fluid level of the reservoir fell markedly due to an intravascular volume loss necessitating fluid supplementation. Thereafter a steady state was reached with a constant fluid need of 0.14 +/- 0.04 ml kg-1 min-1. After start of cooling the fluid needs increased in the following 30 min to 0.91 +/- 0.11 ml kg-1 min-1 in the RC group (P < 0.001) and 0.63 +/- 0.10 ml kg-1 min-1 in the SC-group (P < 0.001) with no statistical between-group differences. Fluid extravasation rates after start of hypothermic CPB increased from 0.20 +/- 0.08 ml kg-1 min-1 to 0.71 +/- 0.13 (P < 0.01) and 0.62 +/- 0.13 ml kg-1 min-1 (P < 0.05) in the RC- and SC-groups, respectively, without any changes in degree of hemodilution. TTW increased in most tissues, whereas the intravascular albumin and protein masses remained constant with no between group differences.

CONCLUSION

Hypothermia increased fluid extravasation during CPB independent of cooling strategy. Intravascular albumin and protein masses remained constant. Since inflammatory fluid leakage usually results in protein rich exudates, our data with no net protein leakage may indicate that mechanisms other than inflammation could contribute to fluid extravasation during hypothermic CPB.

Fluid shifts during cardiopulmonary bypass with special reference to the effects of hypothermia

Background

Generalized overhydration, oedema and organ dysfunction occurs in patients undergoing open heart surgery using cardiopulmonary bypass (CPB) and hypothermia. Inflammatory reactions induced by contact between blood and the foreign surfaces of the extracorporeal circuit are commonly held responsible for the disturbances in fluid balance (‘capillary leak syndrome’). Using the CPB circuit reservoir as a fluid gauge (measuring continuous extracorporeal blood volume), fluid shifts between the intravascular and the extravascular space, and differences between normothermic and moderately hypothermic CPB, were examined.

Methods

Piglets were placed on CPB (thoracotomy) under general anaesthesia. In the normothermic group (n = 7) the core temperature was kept at 38°C before and during 2 h on CPB, whereas in the hypothermic group (n = 7) the temperature was lowered to 29°C during bypass. In addition to accurate recording of fluid during operation, the extracorporeal blood volume was kept constant by maintaining a certain blood level in the CPB circuit's reservoir. Acetated Ringer was used as priming solution in the CPB, as maintenance fluid and for adding fluid to the reservoir if necessary.

Results

Cardiac output, serum electrolytes and arterial blood gases were all similar in the two groups. Haematocrit fell significantly following the start of CPB in both groups. The reservoir fluid level fell markedly in both groups necessitating fluid supplementation. This extra fluid requirement was transient in the normothermic group, but persisted in hypothermic animals. At the end of 2 h of CPB the hypothermic animals had received seven times more extra fluid than the normothermic pigs.

Conclusion

There were strong indications of a greater fluid extravasation induced by hypothermia. The model described, using the PBC circuit reservoir as a fluid gauge, provides the opportunity for further study of fluid volume shifts, their causes and potential ways to manipulate fluid pathophysiology related to hypothermia and to PBC.

Determination of plasma volume in anaesthetized piglets using the carbon monoxide (CO) method

Based on measurements of the circulating red blood cell volume (V(RBC)) in seven anaesthetized piglets using carbon monoxide (CO) as a label, plasma volume (PV) was calculated for each animal. The increase in carboxyhaemoglobin (COHb) concentration following administration of a known amount of CO into a closed circuit re-breathing system was determined by diode-array spectrophotometry. Simultaneously measured haematocrit (HCT) and haemoglobin (Hb) values were used for PV calculation. The PV values were compared with simultaneously measured PVs determined using the Evans blue technique. Mean values (SD) for PV were 1708.6 (287.3)ml and 1738.7 (412.4)ml with the CO method and the Evans blue technique, respectively. Comparison of PVs determined with the two techniques demonstrated good correlation (r = 0.995). The mean difference between PV measurements was -29.9 ml and the limits of agreement (mean difference +/-2SD) were -289.1 ml and 229.3 ml. In conclusion, the CO method can be applied easily under general anaesthesia and controlled ventilation with a simple administration system. The agreement between the compared methods was satisfactory. Plasma volume determined with the CO method is safe, accurate and has no signs of major side effects.

Temperature-related fluid extravasation during cardiopulmonary bypass: an analysis of filtration coefficients and transcapillary pressures

BACKGROUND

Cardiopulmonary bypass (CPB) as used for cardiac surgery and for rewarming individuals suffering deep accidental hypothermia is held responsible for changes in microvascular fluid exchange often leading to edema and organ dysfunction. The purpose of this work is to improve our understanding of fluid pathophysiology and to explore the implications of the changes in determinants of transcapillary fluid exchange during CPB with and without hypothermia. This investigation might give indications on where to focus attention to reduce fluid extravasation during CPB.

METHODS

Published data on "Starling variables" as well as reported changes in fluid extravasation, tissue fluid contents and lymph flow were analyzed together with assumed/estimated values for variables not measured. The analysis was based on the Starling hypothesis where the transcapillary fluid filtration rate is given by: JV=Kf [Pc-Pi-sigma(COPp-COPi)]. Here Kf is the capillary filtration coefficient, sigma the reflection coefficient, P and COP are hydrostatic and colloid osmotic pressures, and subscript 'c' refers to capillary, 'i' to the interstitium and 'p' to plasma.

RESULTS AND CONCLUSION

The analysis indicates that attempts to limit fluid extravasation during normothermic CPB should address primarily changes in Kf, while changes in both Kf and Pc must be considered during hypothermic CPB.

Studies on fluid extravasation related to induced hypothermia during cardiopulmonary bypass in piglets

BACKGROUND

Hypothermia, commonly used for organ protection during cardiopulmonary bypass (CPB), has been associated with changes in plasma volume, hemoconcentration and microvascular fluid shifts. Fluid pathophysiology secondary to hypothermia and the mechanisms behind these changes are still largely unknown. In a recent study we found increased fluid needs during hypothermic compared to normothermic CPB. The aim of the present study was to characterize the distribution of the fluid given to maintain normovolemia. In addition, we wanted to investigate the quantity and quality of the fluid extravasated during hypothermic compared to normothermic CPB.

METHODS

Two groups of anesthetized piglets were studied during 2 h of hypothermic (28 degrees C) (n=7) or normothermic (38 degrees C) (n=7) CPB. Net fluid balance (input-output) was recorded. Changes in colloid osmotic pressures of plasma (COPp) and interstitial fluid (COPi), plasma volume (PV), hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV), s-osmolality, s-albumin and s-total protein was followed throughout the experiments. Fluid extravasation rate was calculated. In addition, total tissue water content was measured and compared with a control group (n=6) (no CPB).

RESULTS

During hypothermic compared with normothermic CPB, the average net positive fluid balance from 10-120 min of extracorporeal circulation was 1.35+/-0.06 ml x kg(-1) x min(-1) and 0.33+/-0.03 ml x kg(-1) x min(-1) respectively (P<0.0001). We found a marked increase in fluid extravasation during hypothermic CPB. The extravasation rate during hypothermia was 1.8+/-0.2 ml x kg(-1) x min(-1), (1st hour) and 1.1+/-0.2 ml x kg(-1) x min(-1) (2nd hour) compared with 0.8+/-0.2 ml x kg(-1) x min(-1), and 0.1+/-(0.1) ml x kg(-1) x min(-1) during normothermia, respectively (P<0.01). The total intravascular protein and albumin masses remained constant in both groups. Following hypothermic CPB, the water content increased significantly in all tissues and organs.

CONCLUSION

During hypothermic CPB an increased extravasation of fluid from the intravascular to the interstitial space was found. As no leakage of proteins could be demonstrated, based on stable values for albumin and protein masses throughout the experiments, the extravasated fluid contained mainly water and small solutes.

Rewarming from accidental hypothermia by extracorporeal circulation. A retrospective study

OBJECTIVE

Twenty-six patients with accidental hypothermia combined with circulatory arrest or severe circulatory failure were rewarmed to normothermia by use of extracorporeal circulation (ECC). The aim of the present study was to evaluate our results.

PATIENTS AND METHODS

The treatment of six female and 20 male patients (median age: 26.7 years; range 1.9--76.3 years) rewarmed in the period 1987--2000 was evaluated retrospectively. Hypothermia was related to immersion/submersion in cold water (n=17), avalanche (n=1) or prolonged exposure to cold surroundings (n=8). Prior to admission, the trachea was intubated and cardiopulmonary resuscitation (CPR) initiated in all patients with cardiorespiratory arrest (n=22), whereas in those with respiration/circulation (n=4) only oxygen therapy via a face mask was given.

RESULTS

Nineteen of the 26 patients were weaned off ECC whereas seven died because of refractory respiratory and/or cardiac failure. Eight of the 19 successfully weaned patients were discharged from hospital after a median of 10 days. One patient died 3 days after circulatory arrest (complete atrioventricular block) resulting in severe cerebral injury. The remaining ten patients died following 1--2 days due to severe hypoxic brain injury (n=5), cerebral bleeding (n=1) or irreversible cardiopulmonary insufficiency (n=4). Based on the reports from the site of accident, two groups of patients were identified: the asphyxia group (n=15) (submersions (n=14); avalanche accident (n=1)) and the non-asphyxia group (n=11) (patients immersed or exposed to cold environment). Seven intact survivors discharged from hospital belonged to the non-asphyxia group whereas one with a severe neurological deficit was identified within the asphyxia group.

CONCLUSION

Patients with non-asphyxiated deep accidental hypothermia have a reasonable prognosis and should be rewarmed before further therapeutic decisions are made. In contrast, drowned patients with secondary hypothermia have a very poor prognosis. The treatment protocol under such conditions should be the subject for further discussion.

Endogenous glutathione and platelet function in platelet concentrates stored in plasma or platelet additive solution

Platelet function was studied in platelet concentrates by assay of the thrombin-induced release of endogenous serotonin and presence of the swirling phenomenon in relation to endogenous glutathione (GSH) and cysteine. In platelets stored in plasma, addition of cysteamine resulted in only a moderate fall in GSH after 5 days of storage, from an average of 14.91 to 11.46 nmol per 109 platelets. Exogenously added GSH had no effect, and addition of buthionine sulfoximine (BSO) resulted in almost complete depletion of GSH, to an average of 0.65 nmol per 109 platelets. Addition of cysteamine or GSH resulted in increased endogenous cysteine whereas BSO had no effect. In platelets stored in a platelet additive solution (T-sol), complete depletion of GSH was found in the presence of cysteamine, GSH and BSO. Endogenous serotonin was unchanged during storage both in plasma and in additive solution (2.8 nmol per 109 platelets). Despite almost total depletion of endogenous GSH, the thrombin-induced release of serotonin after 5 days' storage was significantly affected only in the presence of BSO in platelets stored in additive solution (mean values 72.3% vs. 63.3% of endogeneous serotonin, P < 0.05). Similarly, addition of cysteamine or GSH had no significant effect on swirling but BSO reduced the swirling score after 5 days' storage in platelet additive solution compared with plasma. After 10 days' storage, there was a significant reduction in swirling in the concentrates where BSO was added (P < 0.05).

Cardiac biochemical markers after cardioversion of atrial fibrillation or atrial flutter

BACKGROUND

Cardioversion or defibrillation of cardiac arrhythmias is often necessary in acutely ill cardiac patients. The electrical current may cause elevation of biochemical markers used to diagnose acute myocardial infarction. Therefore it is important to find cardiac markers with high specificity for myocardial necrosis. The purpose of this study was to assess the effects of elective cardioversion of atrial fibrillation or flutter on troponin T and I among conventional markers in patients with no evidence of acute ischemia.

METHODS AND RESULTS

Fifty-seven consecutive patients underwent 1 to 4 direct current shocks (mean cumulative energy 407 J, range 100 to 920 J) under general anesthesia. At baseline, all had normal troponin levels; 50 patients (mean age 68 years, range 33 to 84 years) had normal cardiac enzymes and were included in the final analysis. Blood samples were drawn at baseline, and 1 to 2, 6 to 8, and 20 to 24 hours after cardioversion. The troponin levels were unaffected by cardioversion in all patients, whereas creatine kinase and myoglobin increased more than 10-fold. Creatine kinase MB mass and aspartate aminotransferase were above reference limits in 18% and 24% of patients, respectively, 20 to 24 hours after cardioversion. There was a significant association between elevated creatine kinase, myoglobin, and creatine kinase MB levels with cumulated energy delivered as well as when possible confounders such as age and sex were adjusted for. High international normalized ratio with warfarin use was associated with increased levels of creatine kinase, aspartate aminotransferase, lactate dehydrogenase, and myoglobin.

CONCLUSIONS

The increase of conventional biochemical markers after direct current cardioversion is positively associated with cumulative energy delivered and international normalized ratio (INR) values; neither influences levels of the cardiac troponins.

[Rewarming of patients with accidental hypothermia with the help of heart-lung machine]

BACKGROUND

Different techniques have been used for treatment of victims with accidental hypothermia. We have used cardiopulmonary bypass (CPB) for rewarming hypothermic patients with circulatory failure or cardiac arrest. This report summarises our experiences with this patient group.

MATERIAL AND METHODS

23 patients, submersions (n = 15), avalanche (n = 1) and primary hypothermia (immersion/air cooling) (n = 7), were rewarmed using extracorporeal circulation with standard equipment for open-heart surgery.

RESULTS

On a clinical basis, two patient populations could be identified; one group for whom asphyxia was probably present prior to and during cooling, and another group for whom asphyxia was unlikely. In the first group, one of 13 patients survived compared to the latter group where six out of ten survived. A search for laboratory and other variables that with certainty could contribute to the prediction of prognosis was unsuccessful.

INTERPRETATION

Due to lack of safe prognostic predictors, all accidental hypothermic victims with circulatory failure should be rewarmed by cardiopulmonary bypass before further therapeutic decisions are made.

Serotonin is associated with coronary artery disease and cardiac events

BACKGROUND

Blood platelets are related to coronary atherogenesis. Platelets secrete serotonin (5-hydroxytryptamine) which has several effects on the vascular wall and promotes thrombogenesis, mitogenesis, and proliferation of smooth muscle cells. Serotonin may therefore be one of the factors involved in the development of coronary artery disease (CAD). We have assessed serotonin among conventional predictors for CAD in patients undergoing coronary angiography for chest pain or clinically suspected angina pectoris.

METHODS AND RESULTS

Of 121 consecutive male patients (mean age 65, range 41 to 90 years) undergoing angiography, 96 had coronary artery stenosis and 25 had normal angiograms. Serotonin, blood platelet count, and conventional biochemical risk factors for CAD were determined in the morning the day before the angiography. High serotonin (cut-point 1000 nmol/L) was significantly associated with CAD with an odds ratio (OR) of 3.4 (95% confidence interval 1.2 to 9. 8). The corresponding OR for smokers was 4.8 (1.9 to 12.2); hypercholesterolemia (>7 mmol/L), 2.9 (1.1 to 7.6); high platelet count (cut-point 325 10(9)/L), 3.0 (1.0 to 9.5); and family history of heart disease, 2.3 (1.0 to 5.2). After adjustment with conventional risk factors, the OR for CAD was 3.8 (1.1 to 13.1), comparing high and low values of serotonin. The relation between serotonin and CAD was strengthened only when patients <70 years (n=82) were included in the analysis. In this age group, the occurrence of cardiac events during a mean of 3.7 years of follow-up was significantly associated with high serotonin values.

CONCLUSIONS

The study suggests that serotonin is associated with coronary artery disease and occurrence of cardiac events, particularly in younger age groups. This association seems to persist after adjustment for conventional risk factors.

The swirling phenomenon in stored platelets is influenced by their endogenous serotonin

The presence of the swirling phenomenon is useful to define platelet concentrates that are suitable for transfusion. If it is possible to identify donor-related factors which are related to persisting swirling during storage, it is possible to select platelet donors. Endogenous platelet serotonin content is stable and easily measured and related to agonist-induced serotonin secretion. During a 3-month period, the swirling in 825 single donor platelet concentrates was controlled before issue. Endogenous serotonin, % serotonin release and swirling were tested in 21 concentrates with poor or no swirling during storage. Sixty-three concentrates were randomly selected from the routinely prepared platelet concentrates and were routinely tested with the same analyses on days 1 and 7. To evaluate an obvious effect of endogenous serotonin on the swirling phenomenon, eight platelet concentrates prepared from buffy coat, each from four donors, were divided. One part was stored in the presence of 8.5 micromol serotonin L-1, and analysed as the control concentrates. The endogenous serotonin content in the 'low- swirling' concentrates was significantly lower than in the control group (P < 0.001). PCO2 and pH were significantly lower, and PO2 and MPV significantly higher than in the controls. In the control group, swirling after 7 days was significantly correlated with serotonin release. In the eight buffy-coat concentrates enriched in endogenous serotonin, both swirling and the percentage serotonin release were improved after storage for 10 days, compared with nonenriched concentrates. This study suggests that endogenous serotonin content and serotonin release are factors that may be of significance concerning preservation of the swirling phenomenon in platelet concentrates during storage.

Plasma homocysteine levels and mortality in patients with coronary artery disease

BACKGROUND

Elevated plasma homocysteine levels are a risk factor for coronary heart disease, but the prognostic value of homocysteine levels in patients with established coronary artery disease has not been defined.

METHODS

We prospectively investigated the relation between plasma total homocysteine levels and mortality among 587 patients with angiographically confirmed coronary artery disease. At the time of angiography in 1991 or 1992, risk factors for coronary disease, including homocysteine levels, were evaluated. The majority of the patients subsequently underwent coronary-artery bypass grafting (318 patients) or percutaneous transluminal coronary angioplasty (120 patients); the remaining 149 were treated medically.

RESULTS

After a median follow-up of 4.6 years, 64 patients (10.9 percent) had died. We found a strong, graded relation between plasma homocysteine levels and overall mortality. After four years, 3.8 percent of patients with homocysteine levels below 9 micromol per liter had died, as compared with 24.7 percent of those with homocysteine levels of 15 micromol per liter or higher. Homocysteine levels were only weakly related to the extent of coronary artery disease but were strongly related to the history with respect to myocardial infarction, the left ventricular ejection fraction, and the serum creatinine level. The relation of homocysteine levels to mortality remained strong after adjustment for these and other potential confounders. In an analysis in which the patients with homocysteine levels below 9 micromol per liter were used as the reference group, the mortality ratios were 1.9 for patients with homocysteine levels of 9.0 to 14.9 micromol per liter, 2.8 for those with levels of 15.0 to 19.9 micromol per liter, and 4.5 for those with levels of 20.0 micromol per liter or higher (P for trend=0.02). When death due to cardiovascular disease (which occurred in 50 patients) was used as the end point in the analysis, the relation between homocysteine levels and mortality was slightly strengthened.

CONCLUSIONS

Plasma total homocysteine levels are a strong predictor of mortality in patients with angiographically confirmed coronary artery disease.

Clinical applicability of creatine kinase MB mass and the electrocardiogram versus conventional cardiac enzymes in the diagnosis of acute myocardial infarction

We compared creatine kinase MB (CK-MB) mass and total creatine kinase (CK) sampled three times daily with conventional cardiac enzymes. The influence of the electrocardiogram (ECG) on admission, frequency of blood sampling, thrombolytic therapy, different upper reference limits of the biochemical markers and duration of symptoms were assessed in 100 consecutive patients with suspected AMI of whom 63 were confirmed according to WHO criteria. Early sensitivity but not specificity of CK-MB mass, with and without ECG, for cut points <8 microg/l was significantly better than total CK sampled frequently. The sensitivity of ECG on admission (52%) was significantly improved by CK-MB analysis (79%) but not by total CK. Duration of symptoms (range of means 3.5-9 h) or thrombolytic treatment had no influence on the sensitivity and specificity of CK-MB mass. In AMI with inconclusive ECG, CK-MB mass performed best of the markers with a sensitivity of 70% versus 17% of total CK (P<0.001) on admission. CK-MB mass was also elevated in 8 patients classified conventionally as unstable angina. We conclude that CK-MB mass is a more useful marker of AMI during the first 16 h of chest pain than frequently sampled total CK, ECG and conventional cardiac enzymes.

Serum concentrations of prostate-specific antigen after diagnostic procedures and transurethral microwave thermotherapy of benign prostatic hyperplasia

The objective was to study the effects of diagnostic and therapeutic procedures on serum prostate-specific antigen (PSA) concentration. Urethrocystoscopy in combination with digital rectal examination was followed by a moderate increase of serum PSA for 7-10 days. At 1 day after transurethral microwave thermotherapy (TUMT), an acute and pronounced effect on PSA was observed, which returned to baseline level after 4 weeks. The initial rise in serum PSA corresponded to a PSA density of 1.11, compared to 0.07 at baseline. The present data should be taken into consideration in conjunction with endoscopic evaluation of the lower urinary tract. Additionally, the acute effect on PSA after TUMT strongly suggests the ability of thermotherapy to induce cellular injury and death. One-year follow-up, however, was associated with increased PSA levels, indicating that only a minor part of the PSA-producing compartment was lost in the acute phase.

Proton nuclear magnetic resonance spectroscopy of serum from patients with colorectal neoplasia

Proton nuclear magnetic resonance (NMR) spectra of serum have been recorded from patients with colorectal neoplastic polyps, before and after treatment of colorectal cancer, in patients with advanced lung cancer, and also from healthy controls. Digitally defined NMR profiles of the methyl and methylene peaks were used as input for supervised principal component modelling. An unknown sample was classified according to its residual, i.e. the difference between the spectral pattern of the unknown and control group. There was a statistically significant difference between the mean residual in the untreated colorectal cancer group and in controls (P = 0.003). The sensitivity of detecting untreated colorectal cancer was only 20%. There were no stage-dependent differences between the residuals within the untreated colorectal cancer group. After curative surgery, four patients had recurrence of malignant disease without an increase in residual prior to recurrence. Patients with advanced malignant disease (lung cancer WHO stage IIIB and IV) had a highly significant difference in mean residual from that of controls, with a sensitivity of detecting cancer of 87.5%. This increase in residual could not be explained by increase in the level of serum triglyceride. NMR spectroscopy was not a useful diagnostic tool in patients with colorectal neoplastic polyps and cancer.

The activities of acyl-CoA hydrolase in lysate and subcellular fractions of human blood platelets in relation to activities of acyl-CoA:1-acyl-lysophospholipid acyltransferase

The activities of acyl-CoA hydrolase (EC 3.1.2.2.) and acyl-CoA:1-acyl- lysophospholipid acyltransferase (EC 2.3.1.23) have been studied in subcellular fractions of human platelets. The acyl-CoA:1-acyl-lysophospholipid acyltransferase activity was higher in the 'dense-tubular-system-enriched' fraction than in the 'light-mitochondrial' fraction, using endogenously acyl-CoAs formed from labelled fatty acids, ATP, CoA and various lysophospholipids. No activity was found in the 'particle-free' fraction. No difference in specificities was observed between the incorporation of various fatty acids into different lysoPLs in the subcellular fractions compared with the platelet lysates. Generally, arachidonic, linoleic and eicosapentaenoic acids were better substrates for the acyl-CoA:1-acyl-lysophospholipid acyltransferases than oleic, docosahexaenoic and palmitic acids. The opposite was observed with the acyl-CoA hydrolase activity, palmitoyl-CoA was the substrate giving the highest activity, and eicosapentaenoyl-CoA and arachidonoyl-CoA the lowest. About 85% of the hydrolase activity was detected in the 'particle-free' fraction, with each of the six acyl-CoA derivatives tested.

Normothermic liver ischemia in rats: xanthine oxidase is not the main source of oxygen free radicals

We studied the effect of allopurinol (ALL) on the activity of xanthine dehydrogenase (XDH), xanthine oxidase (XOX), superoxide dismutase (SOD), and catalase (CAT) in rat liver during ischemia followed by 60 min of reperfusion. We induced 60-min ischemia in the median and left lobes by clamping the hepatic artery and portal branches. The percentage XOX relative to total oxidase activity increased significantly in the control group, from 10% during the stabilization period to 18% after 60 min of reperfusion. The XDH activity decreased during reperfusion. Activity of both XDH and XOX was almost completely blocked by ALL. The activity of SOD and CAT did not differ significantly between the ALL group and controls after 60 min of reperfusion. ALL treatment did not affect liver injury parameters, as concentrations of lactate dehydrogenase (LDH) and alanine transferase (ALT) increased in plasma after ischemia, both in controls and in the ALL-treated group. We concluded that ischemia promotes conversion of XDH to XOX during reperfusion. XOX may not be the main source of free radical production, since intracellular scavengers (SOD and CAT) did not differ significantly between controls and the ALL-treated group, despite the fact that ALL blocked XOX activity completely.

Effect of allopurinol on the concentration of endogenous glutathione in hepatocytes after an hour of normothermic liver ischemia

OBJECTIVE

To find out whether oxygen free radical liberated by activation of xanthine oxidase change the tissue concentration of glutathione.

DESIGN

Controlled study.

MATERIAL

42 male Wistar rats.

INTERVENTION

Laparotomy, induction of ischemia, and reperfusion. 27 rats were treated with allopurinol (to inhibit xanthine oxidase) and the remaining 15 acted as controls.

MAIN OUTCOME MEASURES

Concentrations of reduced glutathione, oxidized glutathione, and total glutathione in hepatocytes, blood, and bile.

RESULTS

Concentration of reduced and total glutathione in hepatocytes decreased significantly during reperfusion and oxidized glutathione was unchanged in all groups. Total glutathione in peripheral venous blood was reduced by half during the period of ischemia and increased gradually during reperfusion whereas the concentration of total glutathione in bile decreased appreciable during reperfusion. Production of bile improved significantly during reperfusion in the group treated with allopurinol compared with the control group.

CONCLUSION

Xanthine oxidase may not be the main source of production of oxygen free radicals as allopurinol did not affect the hepatic concentration of glutathione during reperfusion.

The activities of acyl-CoA:1-acyl-lysophospholipid acyltransferase(s) in human platelets

The activities of acyl-CoA:1-acyl-lysophospholipid acyltransferases (EC 2.3.1.23) have been studied in human platelet lysates by using endogenously formed [14C]acyl-CoA from [14C]fatty acid, ATP and CoA in the presence of 1-acyl-lysophosphatidyl-choline (lysoPC), -ethanolamine (lysoPE), -serine (lysoPS) or -inositol (lysoPI). Linoleic acid as fatty acid substrate had the highest affinity to acyl-CoA:1-acyl-lysophospholipid acyltransferase with lysoPC as variable substrate, followed by eicosapentaenoic acid (EPA) and arachidonic acid (AA). The activity at optimal conditions was 7.4, 7.3 and 7.2 nmol/min per 10(9) platelets with lysoPC as substrate, with linoleic acid, AA and EPA respectively. EPA and AA were incorporated into all lyso-forms. Linoleic acid was also incorporated into lysoPE at a high rate, but less into lysoPS and lysoPI. DHA was incorporated into lysoPC and lysoPE, but only slightly into lysoPI and lysoPS. Whereas incorporation of all fatty acids tested was maximal for lysoPC and lysoPI at 200 and 80 microM respectively, maximal incorporation needed over 500 microM for lysoPE and lysoPS. The optimal concentration for [14C]fatty acid substrates was in the range 15-150 microM for all lysophospholipids. Competition experiments with equimolar concentrations of either lysoPC and lysoPI or lysoPE resulted in formation of [14C]PC almost as if lysoPI or lysoPE were not added to the assay medium.

The activity and subcellular distribution of the peroxisomal enzyme acyl-CoA oxidase in human blood platelets

The peroxisomal enzyme acyl-CoA oxidase is localized in the 'dense-tubular-system-enriched fraction', probably identical with the endoplasmic reticulum, in human blood platelets. This localization is strongly different from the localization of catalase which seems to be a cytosolic enzyme, in agreement with Marcus, Zucker-Franklin, Safir & Ullman [(1966) J. Clin. Invest. 45, 14-28]. A localization of acyl-CoA oxidase in the endoplasmic reticulum seems to be in good accordance with the important role of peroxisomes in the metabolism of prostaglandins, as recently demonstrated by Diczfalusy, Kase, Alexson & Bjørkhem [(1991) J. Clin. Invest. 88, 978-984].

Sixty minutes normothermic ischemia in rat liver: the declining tissue concentration of hypoxanthine during reperfusion is not a washout phenomenon

A rat liver normothermic ischemia-reperfusion model was used to investigate whether hypoxanthine (HXA) that accumulated during ischemia was washed out in hepatic veins during reperfusion. Ischemia was induced in median and left lobes by clamping of the proper hepatic artery and portal branches. The effect of allopurinol (ALL) on metabolism of ATP and HXA was studied before, during and after a 60-min normothermic ischemic insult. Liver cell concentration of HXA in the group treated with ALL increased during ischemia and decreased rapidly during the first 10-min reperfusion. Recovery of ATP increased gradually during the 10-min reperfusion period and was significantly higher in the group treated by ALL compared to that of controls. Liver venous blood concentration of HXA in the ALL-treated group was 10-to 40-fold lower than that in liver tissue. The rapidly decreasing concentration of HXA in liver tissue during reperfusion and a minimal washout may indicate that HXA was used for resynthesis of ATP during reperfusion.

Sixty-minute normothermic liver ischemia in rats. Evidence that allopurinol improves liver cell energy metabolism during reperfusion but that timing of drug administration is important

Allopurinol (ALL) improves energy metabolism in organs subjected to ischemia-reperfusion injury. The importance of different administration schedules of ALL has been studied in a rat liver model exposed to 60 min of normothermic ischemia followed by reperfusion. ALL (100 mg/kg) that administered in two doses, one prior to ischemia and one prior to reperfusion, improved production of adenosine triphosphate in the liver as well as bile flow during reperfusion. ALL administered in a single dose, either prior to ischemia or prior to reperfusion, was less effective. The concentration of hypoxanthine during ischemia increased in the groups given ALL prior to induction of ischemia. Based on the present findings, we argue that the beneficial effect of ALL administration can be potentiated by different drug-administration schedules. Our data also suggest that the prime mechanism of action for ALL is not only related to inhibition of free-oxygen-radicals production but that preservation of hypoxanthine, which can be used for ATP resynthesis and the scavenging properties of ALL itself, may be equally important.

Fatty acids in human platelets and plasma. Fish oils decrease sensitivity toward N2 microbubbles

Platelet aggregation induced by N2 microbubbles (simulating microbubbles developed during deep diving) was measured in seven volunteers before and after intake of ethyl-eicosapentaenoate (-EPA, 3.5 g/day) and ethyl-docosahexaenoate (-DHA, 2.5 g/day) for 2 wk. The relative content of arachidonic acid (AA) decreased in platelets from all individuals, whereas the content of EPA and DHA increased. The decrease of AA was almost identical with the increase of EPA plus DHA. In plasma the AA content was unchanged, while EPA and DHA increased. The N2 microbubble-induced aggregation showed a significant negative correlation with the DHA content both in platelets and in plasma. Less aggregation was also observed with high EPA content in platelets or plasma. A significant correlation between AA content in platelets and aggregation was seen. Intake of marine oils may be beneficial to divers under deep diving and to patients during extracorporeal circulation, because this may reduce the microbubble-induced aggregation.

Identity between palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase in human platelet?

Apparent Km values have been determined for the substrates ATP, CoA and fatty acids for the long-chain acyl-CoA synthetase (EC 6.2.1.3) reaction in lysates of human blood platelets. The apparent Km for ATP was higher for saturated fatty acids (C12:0 to C18:0) than for unsaturated acids (C18:1 to C22:6). Other apparent Km values were very similar for all long-chain fatty acids tested. Palmitic acid inhibited the formation of [14C]arachidonoyl-CoA, and arachidonic acid inhibited the formation of [14C]palmitoyl-CoA, with [14C]arachidonate or [14C]palmitate respectively as substrate. After chromatography of Triton X-100-extracted platelet protein in several systems (hydroxyapatite, DEAE-Sepharose, Sephacryl S-200 HR, CoA-Sepharose, Sephadex G-100 and AcA 34), both arachidonoyl-CoA synthetase and palmitoyl-CoA synthetase activities were eluted together in the various protein peaks, and with approximately the same ratio of activities in all peaks. After some purification steps (DEAE-Sepharose and Sephacryl S-200 HR), the acyl-CoA synthetase activity was up to 37 nmol/min per mg of protein with [14C]palmitate as substrate, and up to 116 nmol/min per mg of protein with [14C]arachidonate as substrate. The purification was respectively about 8- and 10-fold. The results indicate that palmitoyl-CoA (or unspecific) synthetase and arachidonoyl-CoA (or specific) synthetase are in fact the same enzyme, in agreement with previously reported results from this laboratory.

[Prostate-specific antigen. A new biological serum marker for prostatic adenocarcinoma]

Prostate-specific antigen (PSA) was measured by polyclonal radioimmunoassay in 45 untreated patients with prostatic cancer and 14 patients with benign prostatic hyperplasia. Prostatic acid phosphatase (PAP) was determined in 35 patients with prostatic cancer and 14 patients with benign hyperplasia. Serum PSA was raised in 42 patients with cancer of the prostate, but only 14 of 35 patients showed increased serum levels of PAP. Half the patients with benign prostate hyperplasia had PSA greater than 4 micrograms/l and one third had PSA greater than 10 micrograms/l. PAP was slightly elevated in two patients with benign prostatic hyperplasia. Serum PSA increased with the clinical stage of prostatic cancer. However, preoperative levels of PSA were not sufficiently reliable to predict the final pathological stage for each individual patient. After radical prostatectomy for cancer confined to the prostate, serum PSA fell to an undetectable level.

Thrombin-induced serotonin release as an in vitro indicator of the functional integrity of stored platelets

Measurements of endogenous serotonin and the thrombin-induced serotonin release reaction in platelet concentrates were compared with other methods of quality control: particle counting and pH and gas analyses. A discrepancy between the serotonin release reaction and the other data was observed after seven days of storage. The decline in the release reaction was not predictable from pH measurements or the number of platelets or leukocytes in the concentrate. There was a significant positive correlation between endogenous serotonin content and the thrombin-induced serotonin secretion after seven days of storage. We conclude that the current methods for routine control of platelet concentrates may not ensure the quality of the product after it has been stored for seven days. The thrombin-induced serotonin release may provide a valuable addition to the battery of tests available.

60 min normothermic liver ischemia in rats: allopurinol improves energy status and bile flow during reperfusion

The effect of allopurinol was studied in a normothermic liver ischemia rat model. Functional (bile flow) and biochemical parameters (high-energy phosphates, ATP, ADP, AMP), energy charge, hypoxanthine and xanthine were determined prior to and during 60 min of ischemia followed by 120 min of reperfusion. Allopurinol given in the preischemic period (50%) and as a bolus (50%) prior to reperfusion improved liver function significantly, whereas allopurinol given in the preischemic period (50%) and after start of reperfusion (50%) had no effect. The data indicates that allopurinol given prior to reperfusion saved hypoxanthine which was used for ATP resynthesis during reperfusion.

Detection of malignant tumours by multivariate analysis of proton magnetic resonance spectra of serum

Proton magnetic resonance spectra of blood serum have been subjected to multivariate data analysis to discriminate between samples from cancer patients and from controls. The main feature was the use of digitally defined resonance profiles. The methyl and methylene lipoprotein signals centred at 1.3 and 0.9 parts per million are non-lorentzian composite peaks that cannot be described properly by the line width at half-height. Instead 71 and 76 data points were used to describe the methylene and methyl peak profiles, respectively. These data points were used as input to a principal component analysis to distinguish between malignant (n = 29) and control samples (n = 55). At a probability level of 0.01 (F-test) modelling classified all patients except 2 correctly, while 1 control was slightly above the predictive level for malignancy.

Thrombin-induced serotonin release as an in vitro indicator of the functional integrity of stored platelets

Measurements of endogenous serotonin and the thrombin-induced serotonin release reaction in platelet concentrates were compared with other methods of quality control: particle counting and pH and gas analyses. A discrepancy between the serotonin release reaction and the other data was observed after seven days of storage. The decline in the release reaction was not predictable from pH measurements or the number of platelets or leukocytes in the concentrate. There was a significant positive correlation between endogenous serotonin content and the thrombin-induced serotonin secretion after seven days of storage. We conclude that the current methods for routine control of platelet concentrates may not ensure the quality of the product after it has been stored for seven days. The thrombin-induced serotonin release may provide a valuable addition to the battery of tests available.

Identical subcellular distribution of palmitoyl-CoA and arachidonoyl-CoA synthetase activities in human blood platelets

Fractionation of human blood platelets showed that palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase activities had an identical distribution among subcellular fractions. The activity was highest with arachidonic acid as substrate in all fractions, with an enzyme activity of 50 nmol/min per mg of protein, in a 'dense-tubular-system'-enriched fraction. The ratio activities with arachidonate and palmitate as substrates was about 1.5 in all fractions. Heat inactivation did not distinguish between arachidonoyl-CoA synthetase and a palmitoyl-CoA synthetase. On the other hand, heat inactivation indicated two pools of long-chain acyl-CoA synthetases: one in a mitochondria- and one in the dense-tubular-system-enriched fraction.

Sixty minutes of normothermic ischemia in the rat liver: correlation between adenine nucleotides and bile excretion

The effect of 60 min of normothermic liver ischemia on cellular levels of adenine nucleotides (ATP, ADP, and AMP), energy charge (EC), and bile excretion was studied. Following ischemia the concentration of ATP was reduced to 12% of preischemic and control values within the first 10 min and remained low during the remaining ischemic period. EC values were also low. During 120 min of reperfusion, ATP increased to 34% of the ATP level found in the control group. EC values increased immediately to reach values not significantly different from those of control animals. Bile flow was nonexistent during ischemia and increased during reperfusion. The increase paralleled those of ATP and EC. Bile flow seems to reflect the degree of liver ischemia and may be used as a functional parameter.