Biomedical subjects
Publications and source records attributed to P Amstutz.
In vitro display techniques are powerful tools to select polypeptide binders against various target molecules. Novel applications include maturation of protein affinity and stability, selection for enzymatic activity, and the display of cDNA and random polypeptide libraries. Taken together, these display techniques have great potential for biotechnological, medical and proteomic applications.
We recently developed a simple and fast assay technique, providing the possibility of monitoring of midazolam (M) during sedation. We compared HPLC vs FPIA for the measurement of the sum M plus alpha 1-hydroxymidazolam (OM), its main and pharmacologically active metabolite, in the serum of sedated ICU patients; this activity referred to as M-like. We identified certain patients in whom M-like activity appeared abnormally high in comparison with HPLC assays. Their common denominators were: long-term sedation with M, and seriously impaired renal function. Further, the conjugates of OM (OMG) accumulated in patients with acute renal failure could contribute to the sedation. We compared the metabolic and analytic behavior of M, OM, and OMG in 2 groups of sedated patients either presenting with normal renal functions (group 1) or with a picture of acute renal failure (group 2). Blood samples were assayed by HPLC and by FPIA and analysis was performed before and after hydrolysis of OMG. Before hydrolysis there was a dramatic accumulation of OMG in the patients of group 2, HPLC vs FPIA results were not different within group 1, while in group 2 the FPIA response exceeded that of HPLC. After hydrolysis, measurement by HPLC was greatly increased in group 2, in each group (vs HPLC) and from one group to another, the FPIA signal (the M-like activity) showed a significant increase. It would be important to take OMG into account as a coprotagonist in sedation whenever circumstances predispose to its accumulation.
Midazolam (M) is used as an induction agent for anesthesia. The main metabolite is alpha-hydroxymidazolam (OM), which is pharmacologically active. Use of M for sedation is a recent application, rapidly gaining favor. Monitoring of the level of sedation is fundamental in that an excessive and prolonged effect is associated with the risk of complications. Thus, it was felt both necessary and useful to measure circulating M levels. We compared a high-performance liquid chromatography (HPLC) assay with fluorescence polarization immunoassay (FPIA) for the measurement of M in the serum of 138 sedated patients in the intensive care unit (i.e., 179 samples). Response of the OM was also assessed. The degree of crossover of the metabolite was between 76.8 and 32.7%. The equation of the regression line for sigma HPLC (i.e., the sum M + OM) versus FPIA was TDx = 1.1585 sigma HPLC + 143.42 (R = 0.966). The 95% confidence interval for the slope was 1.1551, 1.1619. The regression slope differed significantly from 1 (p < 0.001) and shows that FPIA measurements overestimated concentrations obtained by HPLC on the order of 19%. The discrepancy between the two techniques was all the more notable when concentrations were > 1,000 ng/ml. The relative selectivity of Abbott industrial reagent in terms of benzodiazepines leads to the identification of what might be called a midazolam-like (M-like) activity covering both M and OM. The development of a global FPIA method for measurement of this M-like activity in sedated patients provides a satisfactory solution to the question raised.
Disseminated intravascular coagulation (DIC) syndromes can be defined as the formation of fibrin deposits within the microcirculation, occurring in definite clinical situations. Their biological counterpart is a consumption coagulopathy. The clinical profiles of DIC have been well known for decades, are multiform and range from latency to overwhelming haemorrhagic diatheses, including also characteristic but rare situations, such as purpura fulminans, acral cyanosis and pictures resembling thrombotic thrombocytopenic purpura or haemolytic-uraemic syndrome. Biological tests of DIC show a consumption coagulopathy, displayed on the standard haemostasis sheet; along with signs of paracoagulation and/or of secondary fibrinolysis (FDP). New tests have recently been introduced: D-dimers are specific and sensible; Antithrombin-III, protein C and alpha 2-antiplasmin also can sometimes be useful. The knowledge of the pathophysiology of DIC has made advances with passing years. Fibrin deposits may be non-occlusive, and indeed they are swiftly removed by a secondary fibrinolysis. Except in very rare situations, such as those leading to a cortical renal necrosis, and perhaps in some ARDS, there is little evidence relating DIC to organ failure syndromes. Moreover, there is no clear relationship between the severity of the consumption coagulopathy and the prognosis. For instance, the mortality is much lower in abruptio placentae, where the coagulopathy is very severe, than in septic shock, where it is usually moderate. In septic shock, the disorders of haemostasis were related initially to a platelet activation, then to an activation of the contact system (releasing kinins and triggering complement cascade), and nowadays to the activation of the extrinsic coagulation system. The treatment of DIC is mainly the treatment of its cause. Indications for heparin therapy should be strictly limited to a few exceptional circumstances. When haemorrhagic diathesis threatens, FPC and/or platelet transfusion may be indicated. Aprotinin can be useful in rare cases of overwhelming secondary fibrinolysis. Trials with antithrombin-III or C1-esterase inhibitors are in progress.
This study aimed to compare two plasma substitution regimens used during plasma exchanges (PE). It was a prospective cross-over randomized trial. Each patient (n = 12) had two PE at a 48 h interval. During one PE, only albumin was administered (PEA), and during the other one, equal volumes of albumin and low molecular weight hydroxyethylstarch (HES) (Elohes) were given (PEA+E). The order in which these different protocols were used was random. Plasma was separated by filtration, and the total volume extracted was one and a half the plasma volume. The parameters recorded every 15 min until 1 h after the end of PE, were heart rate, blood pressure and central venous pressure (CVP). Plasma volume, calculated from the mean body haematocrit and blood volume, was measured before and after PE. The clinical and biological tolerance of the rapid infusion of a large volume of HES was also assessed. PE characteristics were similar in both groups. For PEA and PEA+E, PE lasted 152 +/- 21 min and 154 +/- 25 min; the plasma volume extracted was 3,907 +/- 772 ml and 3,933 +/- 717 ml; the volume of plasma substitute infused was 4,097 +/- 617 ml and 3,933 +/- 717 ml, respectively. As haemodynamic and biochemical values were not significantly different in both groups, they were pooled together irrespective of the order of PE.(ABSTRACT TRUNCATED AT 250 WORDS)
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A single episode of systemic capillary leak syndrome is reported in a HIV-positive patient. The shock had necessitated the infusion of large amounts of fluid with concomitant diffuse swelling and weight gain leading to compartment syndrome of both legs. This required surgical relief. The initial high hematocrit (62%) and low serum protein concentration (48 g/l) with normal factor V (molecular weight above 300,000) concentrations are the hallmark of capillary leak when they are associated with hypovolemic shock. It must be emphasized that fluid resuscitation may worsen the muscle damage with ultimate compartment syndrome. Therefore, it appears reasonable to monitor muscular pressure during volume expansion in patients with capillary leak syndrome, severe shock and muscular swelling.
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Several lines of evidence implicate tumor necrosis factor (TNF), a cytokine produced by monocytes-macrophages, in the systemic manifestations of shock induced by Gram-negative bacteria. Whether the increase of circulating TNF levels is specific to septic shock as compared to sepsis without shock or to non-septic shock is still unclear. Since TNF values recorded at the time of admission to the hospital vary widely, statistical analysis has not been possible. Therefore, we postulated that the evolution of a patient's TNF serum level as compared to his initial value may better distinguish the survivor from the non-survivor than a single initial determination. Using a radioimmunoassay, we measured the TNF concentrations in the sera of 7 patients with severe infections without shock, 16 patients with septic shock and 8 patients with non-septic shock. Blood samples were drawn within the first 12 hours after the onset of shock. Patients with cancer, HIV infection, or under steroid therapy were excluded. Repeated measurements were made during the first 3 days of septic shock in 10 patients. The circulating TNF level, determined upon admission, appears to be neither specific nor predictive of the outcome of septic shock. In contrast, persistently high levels of circulating TNF seem to be well correlated with a poor prognosis, since 5 out of 6 patients with elevated TNF values died of septic shock.
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In order to investigate the mechanism of polycythemia in chronic obstructive pulmonary disease (COPD), serum and urinary levels of erythropoietin and medullary erythroid progenitors were studied in 21 patients; nine were nonpolycythemic (hematocrit, 39 +/- 4 percent; red blood cell [RBC] mass, 28 +/- 5 ml/kg; forced expiratory volume in one second [FEV1], 0.6 +/- 0.1 L), and 12 patients were polycythemic (hematocrit, 52 +/- 7 percent; RBC mass, 46 +/- 7 ml/kg; FEV1, 0.9 +/- 0.3 L). Hypoxia was severe in both groups, with mean arterial oxygen pressure of 47 mm Hg. The following parameters of tissue oxygenation were not significantly different between the two groups: arterial and mixed-venous oxygen saturations; cardiac output; oxygen utilization coefficient; 2, 3-diphosphoglycerate, and carboxyhemoglobin level. The level of erythropoietin was measured by bioassay in vitro. The level was increased in the serum of 85 percent (18) and in the urine of 38 percent (8) of the patients. There was no significant difference between the nonpolycythemic and polycythemic groups. Without exogenous erythropoietin, none of the subjects showed spontaneous colonies of erythroid progenitors. The addition of one unit of erythropoietin induced a similar normal proliferation of erythroid progenitors in both groups. The absence of adaptative polycythemia in the nonpolycythemic group with severe hypoxia was seemingly related neither to a quantitative deficit of erythropoietin nor to a lack of sensitivity of erythroid progenitors to its action.
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In a group of 27 severely ill patients in an intensive care unit, 40 infections caused by Gram-negative bacilli were treated with temocillin 2g twice daily by the direct intravenous route. The patients (17 men and 10 women) were aged from 35 to 93 years (mean 65.7 years) and 22 had severe underlying diseases. In addition, 10 of the patients were admitted to the intensive care unit following surgery; 6 had acute renal insufficiency, 5 had acute respiratory insufficiency, and 12 were suffering from infectious shock. The infections included septicaemia (19), urinary tract infection (10), respiratory tract infection (4) and biliary tract infection (4). The most frequent bacterial isolate was Escherichia coli (14), followed by Enterobacter cloacae (5), Proteus spp. (5) and Klebsiella pneumoniae (4). The initial pathogens were eliminated in 34/40 infections (85%) and the corresponding clinical cure rate was 60%, with a further 27.5% of patients being improved. In the septicaemic patients, 17/19 pathogens were eradicated from the blood, while clinically, 12 patients were cured and 5 were improved. Eight of the 10 urinary tract pathogens were eliminated, with 6 patients being clinically cured and a further 3 being improved. All of the initial pathogens in both biliary tract and respiratory tract infections were eradicated, accompanied by clinical success in 3 and 2 patients, respectively; the remaining patients were improved. Superinfection with streptococcus group D, Pseudomonas aeruginosa and Staphylococcus aureus was seen in 3 patients. The emergence of resistance to temocillin occurred in an isolate of E. coli, and also possibly in an isolate of K. pneumoniae. No adverse reactions nor abnormal laboratory values related to temocillin administration were observed and, although 7 patients died, none of the deaths were attributable to uncontrolled Gram-negative infection.
One hundred and fourteen spontaneous pneumothorax, idiopathic or with chest disease, were retrospectively analysed in order to compare the efficacy of suction drainage by small lumen IV catheter and by chest tube. Age, importance and tolerance of spontaneous pneumothorax were similar in both groups. Frequency of recidive and failure as well as duration of drainage were also not different. So we advocate the use of suction drainage by small lumen IV catheter. The efficacy is the same than with chest tube. But the technic is more simple and less traumatic.
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We studied the diagnostic value of the detection of soluble pneumococcal antigens by counter-immunoelectrophoresis (ES) in patients with pneumonia. Pneumococcal antigens were detected in blood, urine and pleural fluid. 59 patients were distributed into 3 groups: (Group 1) - 19 patients with a non-pneumococcal, but bacteriologically-proven pneumonia, (Group 2)-32 patients with a bacteriologically confirmed pneumococcal pneumonia, (Group 3)-8 patients with a non-bacteriologically proven pneumonia, but with pneumococcal antigens. No Group 1 patients had pneumococcal antigens. In Group 2 pneumococcal antigens were present in 15 cases. The sensitivity of ES in the detection of soluble pneumococcal antigens (APS) in the blood, urine and pleural fluid during pneumococcal pneumonias was 57.5%. There was a diagnostic benefit when compared to bacteriological analysis alone of 20%. We believe that ES is a useful complementary examination to classical bacteriology.