The value of C-reactive protein for postoperative monitoring of lower limb arthroplasty.

OBJECTIVES: Determination of the utility of C-reactive protein (CRP) levels when measured 21 days after hip and knee arthroplasties for early diagnosis of infectious complications. METHOD: This study was performed in two parts: establishment of a reference curve by measurement of CRP levels once a week in a cohort of 94 patients (50 total hip arthroplasties and 44 total or unicondylar knee arthroplasties); study of the diagnostic value of two different CRP cut-offs (25mg/l, the mean CRP level and two standard deviations; 18 mg/l, mean and one standard deviation) at D21 postoperative in a population of 48 patients, of whom 12 presented septic complications (four surgical site infections [SSIs] and eight intercurrent infections). RESULTS: We observed very high interindividual variations in CRP values two weeks after arthroplasty. These variations decreased strongly in the third week postoperative. In the seven patients with a CRP level above 25mg/l at D21, there were no false-positives. In the 41 patients with a CRP level below 25mg/l at D21, there were five false-negatives and no false-positives. With the CRP threshold set at 18 mg/l, we observed four false-positives and four false-negatives. DISCUSSION-CONCLUSION: A CRP level threshold of 25mg/l is not sufficiently reliable for early detection of postoperative infections (whether at the surgical site or elsewhere), as judged by a sensitivity of 58.3% and a negative predictive value of 87.8%. However, the 25mg/l threshold displays first-rate specificity and positive predictive values (both 100%). A CRP threshold at 18 mg/l is no better because even though it yields slightly a higher sensitivity value (66.7%), it strongly decreases specificity (88.9%). CRP is an important tool for postoperative monitoring but often appears to be difficult to use. The diagnosis of septic complications is based on clinical and paraclinical arguments. Local discharge, fever over 38 degrees C and local/persistent pain and stiffness are more informative indicators of postoperative infection.

Platelet serotonin content and free and total plasma tryptophan in healthy volunteers during 24 hours.

The determination of platelet serotonin (5-HT) and plasma tryptophan concentrations is useful in the diagnosis, investigation of etiologies, and treatment of psychiatric disorders. To determine the usual circadian variations in platelet 5-HT and free and total tryptophan concentrations, we measured these variables during 24 h at 1-h intervals and every 30 min from 2000 to 0800 in seven clinically healthy young men with an HPLC method. No common circadian rhythm for platelet serotonin concentrations was observed in our subjects; however, there was a distinct rhythm for both free and total plasma tryptophan: Concentrations were maximal in the afternoon and minimal during the night.

Increased serotonin platelet uptake after tianeptine administration in depressed patients.

Tianeptine is a new antidepressant drug reported to enhance serotonin (5-hydroxytryptamine [5-HT]) uptake in rat brain. The effect of tianeptine on 5-HT platelet uptake was studied in 10 depressed patients treated for 28 days. Tianeptine increases Vmax of 5-HT platelet uptake during treatment without inducing any change in Km. As early as 2 hr after the first administration, Vmax increased significantly (+23%, alpha = 0.01). Although of a lesser magnitude, 5-HT platelet uptake remains increased after chronic administration (+14% on day 10 and +13% on day 28). This suggests that tianeptine affects 5-HT platelet uptake sites, either directly or via an action on modulators of 5-HT uptake. These results, in contrast with the action of other tricyclic antidepressants, confirm the original action of tianeptine on 5-HT platelet metabolism.

[Platelet serotonin concentration in children under 5 years of age]. / Etude de la concentration en sérotonine plaquettaire chez les enfants de moins de 5 ans.

High platelet serotonin concentrations have been reported in children with early infantile autism. However, as yet there are no reference values regarding platelet serotonin in normal infants and young children so that it remains difficult to define the exact significance of this finding. We report here with the platelet serotonin concentration found in 57 infants and children (20 girls, 37 boys) ranging in age from 10 days to 5 years old. Our results show that mean platelet serotonin concentrations in infants and young children are significantly greater than mean values obtained in older children (+11%) and neonates in the umbilical cord (+64%). No significant variations were found relating to sex, leucocyte count and platelet count. There therefore appears to be a physiological elevation of platelet serotonin concentration in infants and young children, and this has to be taken into consideration in the interpretation of the elevated values found in cases of infantile autism.

Determination of reference values for serotonin concentration in platelets of healthy newborns, children, adults, and elderly subjects by HPLC with electrochemical detection.

We adapted a high-performance liquid chromatographic method with electrochemical detection (Clin Chim Acta 1984;139:1-12) to the determination of platelet serotonin. We used this method to determine platelet serotonin reference values in a healthy population, measuring platelet serotonin concentration in the following subjects: 31 newborns (16 girls, 15 boys); 41 children (11 girls, 30 boys), ages 20 months to 15 years; 56 adults (26 women, 30 men), ages 20 to 58 years; and 20 elderly subjects (16 women, four men), ages 65 to 94 years. There was no significant difference in platelet serotonin concentration between sexes in each age group. However, significant changes (P less than 0.001) were observed between the newborns (mean +/- SD: 1.67 +/- 0.74 nmol/10(9) platelets) and the children (4.09 +/- 1.04) or the adults (3.81 +/- 0.87). Moreover, the platelet serotonin concentration in the elderly subjects (2.57 +/- 1.12) was significantly (P less than 0.001) lower than in the adults and children and significantly higher (P less than 0.01) than in the newborns. Such age-related differences must be taken into consideration when data from neurological or psychiatric patients and control subjects are compared.

A controlled study of Dextran 40: effect on cerebral blood flow and metabolic rates in acute head trauma.

A controlled double-blind evaluation of the effects of Dextran 40 at different concentrations on cerebral blood flow (CBF), cerebral oxygen consumption (CMRO2) and cerebral lactate production (CMRLact) was carried out. We studied 40 patients in coma due to recent head injury. Concentrations of Dextran solution were not significantly related to variations in CBF and metabolic rate over the period of infusion. The lack of effect of the Dextran infusion may be explained by the absence of global brain ischemia in these patients at the time of the study. The very low initial CBF values were a consequence of brain metabolic depression and not a sign of global ischaemia. The rheological benefits of treatment with Dextran 40 in head injured patients should preferably be investigated using techniques which permit detection of local changes in CBF and metabolism.

[Evaluation of the treatment with fenfluramine of autism in children]. / Evaluation du traitement par la fenfluramine dans l'autisme infantile.

The effects of fenfluramine were studied in a group of 44 children with the autistic syndrome and in 26 non autistic children with behavior abnormalities, mostly hyperkinetic children, as a control group. The mean daily dosage was 0.65 mg/kg/day. There were 75% positive results in the autistic children and 77% in the control group. The clinical improvement appears to be mainly related to the control of the hyperactive behavior in the autistic children. Platelet serotonin levels were studied in both groups, showing a clear cut decrease during fenfluramine therapy with no significant differences between the 2 groups and no correlation between the clinical effects and the magnitude of the decrease.

[Platelet serotonin concentrations in autistic children and members of their families]. / Etude de la concentration en sérotonine plaquettaire chez des enfants autistes et parmi les membres de leurs familles.

Children with early infantile autism have often high platelet serotonin (5 HT) levels. According to this fact, we wondered if a genetic abnormality of 5 HT metabolism could be detected in family members of autistic children. We has thus determined platelet 5 HT levels in these children's mothers, fathers and siblings. It is noteworthy to find out that: autistic children have a mean platelet 5 HT level significantly higher than their siblings' (p less than 0.01); fathers' levels are significantly lower (-29%; p less than 0.001) than those of other family members' and of control group. Furthermore, for future purposes, we studied platelet 5 HT levels at different times during pregnancy in controls and in a woman already mother of an autistic child. We observed a raise (+31%; p less than 0.01) in platelet 5 HT during the first trimester of the pregnancy with a lowering towards normal levels during the eight month, in the woman with an autistic child as well as in the controls.

[Classification of chronic psychoses types I and II and platelet serotonin levels. Apropos of 38 cases]. / Classification des psychoses chroniques en type I et II et concentration en sérotonine plaquettaire. A propos de 38 cas.

The authors have examined, within a population of 38 patients, all suffering from chronic psychosis, the concentration of serotonin in the blood platelets as a function of a psychopathologic classification. The 38 patients, 17 men and 21 women, with a mean age of 46 years, diagnosed as schizophrenics (INSERM classification) were categorized according to their specific psychosis (types I and II of J. Guyotat) on examination of their clinical reports by two independent clinicians. This categorization returned 20 psychotics of type I, 16 psychotics of type II and 2 psychotics were difficult to classify. Blood samples were taken from both patients and from 47 controls at 10 o'clock in the morning, two hours after breakfast. The concentration of serotonin in the blood platelets was subsequently examined using the technique of liquid chromatography. The results obtained did not show any significant difference between the chronic psychotics and the control group. The average level of platelet serotonin is 5.09 for psychosis of type I and 3.56 for psychosis of type II, but the value of this difference does not indicate a significant statistical difference; however the tight grouping of serotonin levels in the psychotics of type II looked interesting because they were similar to those of the control in being more homogeneous than those of the psychotics of type I.

Assessment of the benzethonium chloride method for routine determination of protein in cerebrospinal fluid and urine.

We have tested the characteristics of the method of Iwata and Nishikaze (Clin Chem 25: 1317, 1979). The linearity, sensitivity, and precision are satisfactory and the reactivity of benzethonium chloride with various proteins (albumin, immunoglobulins) is the same. The method has been compared with Meulemans's technique (Clin Chim Acta 5: 757, 1960), routinely used in our laboratories, by analysis of 82 samples of cerebrospinal fluid (CSF) and 119 samples of urine. Our results for cerebrospinal fluid agree well with those of Iwata and Nishikaze (r = 0.976; y = 0.992x - 0.013), but we find their method unsuitable for urinary protein determination, probably because of interfering compounds in urine.

[Valve of the use of benzethonium chloride for turbidimetric analysis of cerebrospinal fluid proteins with an automatic analyzer]. / Intérêt de l'utilisation du chlorure de benzéthonium pour le dosage turbidimétrique des protéines du liquide céphalorachidien en analyse automatique.

We have adapted Iwata and Nishikaze's benzethonium chloride turbidimetric method for the assay of CSF proteins to the techniques of continuous flow and the centrifuge analyser. The proposed technique presents several advantages: benzethonium chloride forms a stable precipitate with the proteins with a slow kinetic of formation, enabling adaptation to the centrifuge analyser; the response obtained is identical for albumin and immunoglobulin G; this very sensitive technique allows the use of micro-samples. Studies of repeatability and the correlations made with other techniques give very satisfactory results.