Plasma concentrations following repeated rectal or intravenous administration of paracetamol after heart surgery.

BACKGROUND: Paracetamol is commonly used for post-operative pain management in combination with more potent analgesics. The best route of paracetamol administration after major surgery, when oral intake may not be optimal, is not known. Our primary purpose was to study plasma concentrations after the 1st and 4th dose of 1 g of paracetamol given either rectally or intravenously (i.v.) after major surgery. METHODS: In this prospective, randomized study, 48 patients undergoing heart surgery were randomized upon arrival to the intensive care unit (ICU) to receive paracetamol every 6th hour either as suppositories or intravenous injections. In half the patients (n = 24), blood samples for paracetamol concentration were obtained before and 20, 40 and 80 min after the first dose. In the other patients (n = 24), additional samples were taken prior to, and at 20, 40, 80 min and 4 and 6 h after, the 4th dose. RESULTS: Plasma paracetamol concentration peaked (95 +/- 36 micromol/l) within 40 min after initial i.v. administration but did not increase within 80 min after the 1st suppository. Plasma concentration before the 4th dose was 74 +/- 51 and 50 +/- 27 in the rectal and i.v. groups, respectively. Paracetamol concentration peaked 20 min after the 4th dose for the i.v. patients (210 +/- 84 micromol/l) and declined to 99 +/- 27 micromol/l at 80 min as compared with the rectal patients 69 +/- 44 to 77 +/- 48 micromol/l. CONCLUSION: Both time course and peak plasma concentrations of paracetamol given rectally differ from the one seen after intravenous administration. The clinical impact of these differences needs further investigation.

Early bioavailability of paracetamol after oral or intravenous administration.

BACKGROUND: Paracetamol is a peripherally acting analgesic commonly used in multimodal post-operative pain management to reduce the need for more potent analgesics with their unwanted side-effects. The dose and optimal galenical form for achieving analgesic concentrations is not well defined. The primary aim of this pilot project was to study the early bioavailability for two fixed doses of orally administrated paracetamol and one dose of intravenous propacetamol, all of which were given after minor surgery. METHODS: Thirty-five patients undergoing day surgery were divided into five groups, seven patients each. Groups received either 1 g of an ordinary paracetamol tablet, 2 g of an ordinary paracetamol tablet, 1 g of a bicarbonate paracetamol tablet, 2 g of a bicarbonate paracetamol tablet or 2 g intravenously of prodrug propacetamol. We studied the plasma concentration of paracetamol during the first 80 min after administration. RESULTS: Within 40 min, intravenous propacetamol gave a median plasma paracetamol concentration of 85 micromol/l (range 65-161) and decreased thereafter. After oral administration, median plasma paracetamol concentration increased with increasing dose and time, but there were huge inter-individual differences at all time points studied. At 80 min after oral paracetamol the median plasma concentrations were 36 and 129 micromol/l for the 1- and 2-g groups, respectively, with an overall range between 0 and 306 micromol/l. CONCLUSION: Oral administration of paracetamol as part of multimodal pain management immediately post-operatively resulted in a huge and unpredictable variation in plasma concentration compared with the intravenous administration.

Role of the glutamyl alpha-carboxylate of the substrate glutathione in the catalytic mechanism of human glutathione transferase A1-1.

The Glu alpha-carboxylate of glutathione contributes to the catalytic function of the glutathione transferases. The catalytic efficiency of human glutathione transferase A1-1 (GST A1-1) in the conjugation reaction with 1-chloro-2,4-dinitrobenzene is reduced 15 000-fold if the decarboxylated analogue of glutathione, dGSH (GABA-Cys-Gly), is used as an alternative thiol substrate. The decrease is partially due to an inability of the enzyme to promote ionization of dGSH. The pK(a) value of the thiol group of the natural substrate glutathione decreases from 9.2 to 6.7 upon binding to GST A1-1. However, the lack of the Glu alpha-carboxylate in dGSH raised the pK(a) value of the thiol in the enzymatic reaction to that of the nonenzymatic reaction. Furthermore, K(M)(dGSH) was 100-fold higher than K(M)(GSH). The active-site residue Thr68 forms a hydrogen bond to the Glu alpha-carboxylate of glutathione. Introduction of a carboxylate into GST A1-1 by a T68E mutation increased the catalytic efficiency with dGSH 10-fold and reduced the pK(a) value of the active site bound dGSH by approximately 1 pH unit. The altered pK(a) value is consistent with a catalytic mechanism where the carboxylate contributes to ionization of the glutathione thiol group. With Delta(5)-androstene-3,17-dione as substrate the efficiency of the enzyme is decreased 24 000-fold while with 4-nitrocinnamaldehyde (NCA) the decrease is less than 150-fold. In the latter reaction NCA accepts a proton and, unlike the other reactions studied, may not be dependent on the Glu alpha-carboxylate for deprotonation of the thiol group. An additional function of the Glu alpha-carboxylate may be productive orientation of glutathione within the active site.

The role of glutathione in the isomerization of delta 5-androstene-3,17-dione catalyzed by human glutathione transferase A1-1.

Human glutathione transferase (GST) A1-1 efficiently catalyzes the isomerization of Delta(5)-androstene-3,17-dione (AD) into Delta(4)-androstene-3,17-dione. High activity requires glutathione, but enzymatic catalysis occurs also in the absence of this cofactor. Glutathione alone shows a limited catalytic effect. S-Alkylglutathione derivatives do not promote the reaction, and the pH dependence of the isomerization indicates that the glutathione thiolate serves as a base in the catalytic mechanism. Mutation of the active-site Tyr(9) into Phe significantly decreases the steady-state kinetic parameters, alters their pH dependence, and increases the pK(a) value of the enzyme-bound glutathione thiol. Thus, Tyr(9) promotes the reaction via its phenolic hydroxyl group in protonated form. GST A2-2 has a catalytic efficiency with AD 100-fold lower than the homologous GST A1-1. Another Alpha class enzyme, GST A4-4, is 1000-fold less active than GST A1-1. The Y9F mutant of GST A1-1 is more efficient than GST A2-2 and GST A4-4, both having a glutathione cofactor and an active-site Tyr(9) residue. The active sites of GST A2-2 and GST A1-1 differ by only four amino acid residues, suggesting that proper orientation of AD in relation to the thiolate of glutathione is crucial for high catalytic efficiency in the isomerization reaction. The GST A1-1-catalyzed steroid isomerization provides a complement to the previously described isomerase activity of 3beta-hydroxysteroid dehydrogenase.

Patient-controlled versus nurse-controlled pain treatment after coronary artery bypass surgery.

BACKGROUND: Pain after coronary artery bypass surgery persists for several days. A continuous intravenous infusion of an opioid adequately accomplishes good pain control in the intensive care unit, but it is often not suitable on the ordinary ward. Patient-controlled analgesia (PCA) with intermittent injections delivered by one of the new devices now available could be an alternative to conventional nurse-controlled analgesia (NCA) based on intermittent injections. The aim was to compare these two techniques with respect to efficacy and the amount of opioid used. METHODS: Forty-eight patients randomly received PCA or NCA with ketobemidone following extubation after coronary artery bypass grafting. Drug consumption, pain assessment with the visual analogue score (VAS) and possible side effects were evaluated from extubation to the end of the second postoperative day. RESULTS: On the day of surgery the VAS scores did not differ between the groups. From the afternoon of the first postoperative day the VAS scores were higher in the NCA group with mean values at 3-4 out of 10 as compared with mean values around 2 in the PCA group (P<0.01). During the study period the patients in the PCA group received more ketobemidone as compared with the NCA group, 61.9+/-24.0 mg and 36.3+/-20.2 mg, respectively (P<0.01). Additional oral analgesics were used in 12 of the patients in the NCA group compared with none in the PCA group. The few side effects reported were equally distributed between the two groups. CONCLUSION: PCA treatment after coronary artery bypass surgery resulted in better pain treatment and the use of more opioid without an increase in side effects compared with traditional NCA treatment.

An evolutionary approach to the design of glutathione-linked enzymes.

Studies of protein structure provide information about principles of protein design that have come into play in natural evolution. This information can be exploited in the redesign of enzymes for novel functions. The glutathione-binding domain of glutathione transferases has similarities with structures in other glutathione-linked proteins, such as glutathione peroxidases and thioredoxin (glutaredoxin), suggesting divergent evolution from a common ancestral protein fold. In contrast, the binding site for glutathione in human glyoxalase I is located at the interface between the two identical subunits of the protein. Comparison with the homologous, but monomeric, yeast glyoxalase I suggests that new domains have originated through gene duplications, and that the oligomeric structure of the mammalian glyoxalase I has arisen by 'domain swapping'. Recombinant DNA techniques are being used for the redesign of glutathione-linked proteins in attempts to create binding proteins with novel functions and catalysts with tailored specificities. Enzymes with desired properties are selected from libraries of variant structures by use of phage display and functional assays.

Body fat distribution and left ventricular morphology and function in obese females.

OBJECTIVE: To study left ventricular function and morphology in non-hypertensive obese females and to relate the findings to body mass index (BMI) and to an index of body fat distribution (waist:hip ratio). DESIGN: Cross-sectional study. SETTING: Obesity unit in city hospital. SUBJECTS: Healthy obese females (n = 22) with BMI > 25 and < 40 kg/m2 and a non-obese, age-matched control group (n = 20) with BMI < 25 kg/m2. MAIN OUTCOME MEASURES: Blood pressure and non-invasive indices of left ventricular morphology and diastolic and systolic function. RESULTS: The obese group had significantly higher blood pressure, larger left ventricular end-diastolic diameter, greater left ventricular mass; larger left atrial size, signs of decreased left ventricular distensibility and prolonged left ventricular relaxation time index, and signs of supernormal systolic left ventricular function (as judged from the relationship between fractional shortening and end-systolic wall stress) than the non-obese controls. The results also indicated that left ventricular wall thickness and mass were well adapted to the increase in afterload, as judged by analyses of end-systolic wall tension and end-systolic wall stress. CONCLUSION: In confirmation of several previous studies, obesity was closely associated with an increase in blood pressure and left ventricular mass, and with early signs of disturbed left ventricular diastolic function. Left ventricular wall thickness and mass were well adapted to the increase in afterload; thus, we could not identify any non-afterload-dependent effect of an increase in BMI or waist:hip ratio on left ventricular hypertrophy.

A 3-year follow-up study on single implant treatment.

The purpose of this study was to investigate restorative and postinsertion problems in patients provided with single implant supported restorations. Fifty consecutive single implant patients were reviewed over a period of 3 years following placement of artificial crowns. One (1.4%) of the 70 inserted implants was lost during the follow-up period, which gives a cumulative success rate of 98.5%. The most frequent complication was loosening of the single tooth abutment screw. This problem was associated with fistulas during the first year of clinical service. A more severe complication was that three adjacent teeth had to be endodontically treated due to accidental devitalization from surgical trauma during implant insertion. The mean marginal bone level adjacent to the implants was reduced 0.5 mm from crown insertion to the third annual review.

One-year prognosis in patients hospitalized with a history of unstable angina pectoris.

The prognosis during 1 year of follow-up in 715 patients admitted to one single hospital due to suspected acute myocardial infarction (AMI) with a history of unstable angina pectoris immediately preceding hospitalization is described. AMI developed in 192 patients (27%) during the first three days and in 255 patients (38%) during the first year. The mortality during hospitalization was 7% (50 patients) and during 1 year 19% (130 patients). Of the nonsurvivors, 54% died of AMI, 28% of congestive heart failure, and 20% of cardiogenic shock. Based on simple clinical parameters on admission to the emergency room, risk indicators for death during the following year could be identified as follows, in the order of significance: high age (p < 0.001), ST-segment depression on admission (p < 0.001), and a history of diabetes mellitus (p < 0.05). At admission to the emergency room, risk indicators for development of AMI during the following year were as follows: initial degree of suspicion of AMI (p < 0.001), electrocardiographic signs of acute ischemia on admission (p < 0.001), ST-segment elevation on admission (p < 0.01), age (p < 0.05), and lack of a previous history of chronic stable angina pectoris (p < 0.05). We conclude that, among patients admitted to hospital due to suspected AMI with a history of unstable angina pectoris immediately preceding hospitalization, 38% developed a confirmed infarction and 19% died during the following year.

Distribution of adipose tissue and muscle mass in alcoholic men.

An elevated waist to hip ratio (WHR) has been found to be a predictor for several prevalent diseases. To examine the potential role of alcohol in the elevation of WHR, established alcoholic men without severe liver damage who were in adequate nutritional condition were compared with organized teetotalers matched for age, height, and body weight; the groups had similar total body fat content and lean body mass. Computed tomographic (CT) measurements at thigh and trunk levels showed a significant increase in the visceral adipose tissue (AT) areas and a slight decrease of muscle areas in the gluteal and femoral regions of the alcoholics. The alcoholic men had 48% of their AT areas of trunk scans localized retroperitoneally and intraperitoneally compared with 38% for the teetotalers (P < .01). The difference seemed to be more marked for retroperitoneal than for intraperitoneal AT (97 v 60 cm2, P < .01). The elevated visceral AT areas seemed to be independent of smoking. It was concluded that the increased WHR of alcoholics may include not only changes in AT, but also in muscle tissue distribution.

Characteristics and prognosis of patients with acute myocardial infarction in relation to whether they were treated in the coronary care unit or in another ward.

The characteristics and the prognosis in 921 consecutive patients with acute myocardial infarction (AMI) admitted to one single hospital are described and related to whether they were treated in the coronary care unit or not. Patients treated in the coronary care unit (n = 779) had a 1-year mortality rate of 26% as compared with 41% for patients treated in general wards (n = 115; p < 0.001) and 74% for patients treated in the intensive care unit (n = 27; p < 0.001). Patients treated outside the coronary care unit had a different risk factor pattern including a higher age and a higher prevalence of a previous cardiovascular disease. Independent clinical risk indicators for death among patients in the coronary care unit were in order of significance, high age (p < 0.001), arrhythmia on admission (p < 0.01), acute congestive heart failure on admission (p < 0.01) and a history of diabetes mellitus (p < 0.05). In patients treated in general wards, the only risk indicator for death was a history of congestive heart failure.

Patients admitted to the emergency room with symptoms indicative of acute myocardial infarction.

All 7157 patients (55% men) admitted to the emergency room with chest pain or other symptoms indicative of acute myocardial infarction during a period of 21 months were registered consecutively. Chest pain was reported by 93% of the patients. On the basis of history, clinical examination, and electrocardiogram in the emergency room, all patients were prospectively classified in one of four categories: (i) obvious infarction (4% of all patients); (ii) strongly suspected infarction (20%); (iii) vague suspicion of infarction (35%); and (iv) no suspected infarction (41%). In patients with no suspected infarction (n = 2910), musculoskeletal (26%), obscure (21%) and psychogenic origins (16%) of the symptoms occurred most frequently. We conclude that few of the patients had an obvious infarction on admission, and that a musculoskeletal origin of the symptoms occurred most frequently in patients with no suspected infarction.

The metabolism of ethyl esters of fatty acids in adipose tissue of rats chronically exposed to ethanol.

The concentration of ethyl esters of fatty acids as well as the activity of the enzyme synthesizing these esters (fatty acid ethyl ester synthase) were determined in adipose tissue of rats ingesting ethanol (9-16 g/kg body weight/day) for different periods of time. After 10 and 17 weeks of ethanol exposure about 300 nmol of ethyl esters of oleic, palmitic, stearic, and linoleic acids were found per gram adipose tissue. The ethyl esters disappeared after 1 week of abstinence. Closer analyses, using radioactive ethanol, revealed a half-life of the esters of less than 24 hr. The bulk of the esters was found in a membrane preparation of isolated adipocytes. Hormone-sensitive lipase hydrolyzed emulsified ethyl oleate as efficiently as that of trioleoylglycerol, but in mixed ethyl oleate/trioleoyl glycerol particles the hydrolysis of ethyl oleate was slower, suggesting a decreased accessibility. Synthase activity was found in adipose tissue from rats not exposed to ethanol. It doubled after 10 and 17 weeks of ethanol and decreased with a half-life of at least a week after abstinence. It was concluded that ethyl esters of fatty acids are formed in rat adipose tissue as previously shown in other tissues. They seem to be stored mainly in membranous parts of the adipocytes. Synthase activity is induced by ethanol. The elevated activity has a longer half-life, and may be useful as an indicator of alcohol abuse.

Prognosis in suspected acute myocardial infarction in relation to delay time between onset of symptoms and arrival in hospital.

During a 21-month period, the prognosis in all patients admitted to a hospital ward from the emergency room with suspected acute myocardial infarction (AMI) was prospectively recorded and related to the time between onset of symptoms and arrival in hospital. They were classified as early arrivers (less than or equal to 2 h), intermediate arrivers (2-8 h) and late arrivers (greater than 8 h). Among patients developing a confirmed AMI (n = 909) the 1-year mortality rate was 26.0% in early arrivers, 28.1% in intermediate arrivers and 32.6% in late arrivers. The corresponding figures for patients in whom AMI was ruled out (n = 2,035) were 15.2, 15.1 and 17.6%, respectively. In AMI patients, various morbidity aspects during hospitalization and 1 year of follow-up appeared mainly independent of delay time, whereas among those in whom AMI was ruled out congestive heart failure during hospitalization was most common in early arrivers. We conclude that patients with suspected AMI who do not arrive early in hospital have a high 1-year mortality rate regardless of whether they develop AMI or not. Whether their prognosis can be improved by shortening of delay time remains to be clarified.

Alcohol consumption and synthesis of ethyl esters of fatty acids in adipose tissue.

Ethyl esters of fatty acids (EEFA) have been found to be formed during ethanol metabolism. Human adipose tissue contains high concentrations of free fatty acids, the substrate for EEFA synthesis, and might therefore be a tissue with great potential for EEFA formation. In order to explore their potential usefulness as markers of alcohol abuse, the EEFA concentration and the activity of EEFA-synthesizing enzyme were therefore determined in adipose tissue from men belonging to the following categories: teetotalers, social drinkers, alcoholics under treatment, or established alcoholics found to have died as a result of alcohol intoxication. In order to estimate the half-life of EEFA and the synthase activity induction, the alcoholics were examined after different time periods of abstinence from alcohol. Comparisons were also made with several established markers of alcohol abuse. EEFA were not found in teetotalers, and were found in low concentrations in some of the social drinkers. EEFA were found in several alcoholics, and the forensic cases had high concentrations. EEFA-synthesizing enzyme activity was found in all subjects, increasing from teetotalers to social drinkers, and being 2-fold higher in alcoholics and 5-fold higher in dead alcoholics. The induction of the enzyme after abstinence appeared to have a half-life of the order of several weeks. Correlations were found between EEFA synthase activity and previously established markers of alcohol abuse known to remain for a long time period after abstinence, such as mean erythrocyte corpuscular volume. This preliminary study suggests the possibility that EEFA synthase induction in adipose tissue might have a longer half-life than previously used markers of alcohol abuse. It is therefore suggested that the induction of EEFA synthase might be a potentially useful new marker for alcohol abuse because of its apparent proportionality to alcohol intake over a prolonged time period, its presumed specificity, and long-term elevation after alcohol abstinence. This potential marker should be analysed further.

Ultimate limits for the reaction flux and metabolite levels that may be evolutionarily reached in a linear metabolic pathway.

A relationship is derived for the maximum steady-state reaction rate that may be supported by an enzyme catalysing substrate/product interconversion by a generalized Michaelian mechanism for a single-substrate reaction. This relationship is used to characterize the ultimate kinetic and thermodynamic limits for the evolutionary improvement of a linear metabolic sequence of reactions catalysed by Michaelian enzymes in response to a selective pressure in the direction of increased reaction flux. A mathematical analysis is presented which provides explicit expressions for the maximum reaction flux and metabolite concentrations that can be evolutionarily reached in such a pathway. These expressions may be used to obtain information on the reaction steps that represent ultimate bottlenecks for the attainment of high reaction flux in a certain pathway and to identify the enzymes that ultimately are likely to exert main flux control.

Fat distribution and steroid hormones in women with alcohol abuse.

Anthropometric, hormonal and liver function parameters were examined in 18 premenopausal women with a history of early alcohol abuse, and compared with the data for randomly selected controls of the same age. The alcoholic women showed slightly elevated levels of transaminases, but no clinical or laboratory signs of advanced liver damage. These women were characterized by an increased waist-to-hip ratio, due to enlarged waist circumference. Several endocrine abnormalities were found, including irregular or absent menses as well as low oestrogen, progesterone and delta-4-androstendione levels. The concentration of free testosterone was high and that of sex-hormone-binding globulin was low. These data suggest abdominal distribution of body fat, as well as hyperandrogenicity in alcoholic, premenopausal women. It is postulated that the endocrine abnormalities might be responsible for the abdominal fat distribution.

Stable storage conditions of Immobiline chemicals for isoelectric focusing.

Most of the problems connected with the use of the Immobiline chemicals (a set of six, non-amphoteric, acrylamido buffers having pK values in the pH 3.5-9.5 interval) can be attributed to the alkaline species (with pK values 6.2, 7.0, 8.5 and 9.3). These compounds, to varying degrees are subjected to two degradation pathways: (a) hydrolysis of the amido bond, producing free acrylic acid and a diamine, the latter unable to be incorporated into the polyacrylamide matrix; (b) spontaneous auto-polymerization, producing a number of oligomers up to n-mers, able to aggregate and precipitate large proteins. Storage of their water solutions as frozen aliquots, a method widely employed, only partially alleviates the problem. Addition of trace-amounts of inhibitors, as lately adopted by the manufacturer, could only reduce the problem of auto-polymerization, but not block the hydrolysis of the amido bond. A new solution has been found, which abolishes both phenomena: storage in n-propanol. As demonstrated by gas chromatography, HPLC analyses and two-dimensional separations of complex samples, storage in organic solvent completely abolishes both hydrolysis and auto-polymerization and allows production of highly reproducible focusing patterns.

Studies on the chromatographic fractionation of metabolites of benzo[a]pyrene in faeces and urine from germfree and conventional rats.

Rats, germfree and conventional, were dosed with 14C-labelled benzo[a]pyrene. Faeces and urine were collected. Metabolites in faeces were effectively extracted with a new method using a combination of solvents and solid sorbents. Metabolites in urine were extracted with octadecylsilane-bonded silica. The metabolites were fractionated into groups by chromatography on a cation exchanger (SP-LH-20 or SP-Sephadex C-25) and an anion exchanger (TEAP-LH-20). Some of the groups were further purified by column chromatography and analysed by HPLC and TLC. The analyses show a complex pattern of metabolism. A large part of the metabolites (9-24% depending on animal type and route of excretion) had amphoteric properties, e.g. like glutathione and cysteine conjugates. The abundance of conjugates sensitive to beta-glucuronidase and sulphatase was low. The relative amount of acidic conjugates in faeces was much higher in the germfree than in the conventional rats indicating the influence of the intestinal flora on the metabolism. The results support the view that the mercapturic acid pathway is a quantitatively important metabolic route for benzo[a]pyrene in rats. The methods of extraction and group fractionation were designed to be generally applicable to the analysis of lipophilic xenobiotics and their metabolites.

Insulin binding in differentiating rat preadipocytes in culture.

Binding, degradation, and antilipolytic effect of insulin were studied during the differentiation of preadipocytes into unilocular adipocytes. The precursor cells were isolated from the stromal-vascular fraction of adult rat epididymal fat pads and were cultured according to methods previously described. Under appropriate conditions the cells attained full morphological maturation after 6 days. A gradual increase in insulin binding was found concomitant with the morphological development of the preadipocytes into adipocytes. This increase was due to an enhanced number of binding sites whether expressed per cell or per unit cell surface area. The presence of a high insulin concentration (1.67 micrograms/ml or 278 nM) in the culture medium did not prevent this effect. The receptor density, expressed per unit surface area, was higher in the newly developed univacuolar cells than in mature fat cells from the same rat. The increased receptor density was also reflected by a leftward shift in the dose-response curve for the antilipolytic effect of insulin. In parallel with the increased binding, insulin degradation also increased. The lipolytic response to catecholamine also showed a gradual increase with development. When expressed per unit surface area, newly formed cells exhibited a considerably greater response (approximately 3.4 times) than mature cells from the same animals. The maximal antilipolytic effect of insulin in new cells was of the same order as in old cells when the data were expressed per unit cell surface area. Thus, the data show that developing adipocyte precursors gain membrane properties similar to those of mature fat cells. This cell system may serve as a useful model for studying receptor formation and factors that regulate hormone responsiveness.