The effect of increased classroom ventilation rate indicated by reduced CO2 concentration on the performance of schoolwork by children

The article reports on an experiment which investigated the effect of increased classroom ventilation rate on the performance of children aged 10-12 years. The experiment was executed at two different schools (two classrooms at each school) as a double-blind 2 × 2 crossover intervention where four different performance tests were used as surrogates for short-term concentration and logical thinking. Only complete pairs of test responses were included in the within-subject comparisons of performance, and data were not corrected for learning and fatigue effects. Analysis of the total sample suggested the number of correct answers was improved significantly in four of four performance test, addition (6.3%), number comparison (4.8%), grammatical reasoning (3.2%), and reading and comprehension (7.4%), when the outdoor air supply rate was increased from an average of 1.7 (1.4-2.0) to 6.6 l/s per person. The increased outdoor air supply rate did not have any significant effect on the number of errors in any of the performance tests. Results from questionnaires regarding pupil perception of the indoor environment, reported Sick Building Syndrome symptoms, and motivation suggested that the study classroom air was perceived more still and pupil were experiencing less pain in the eyes in the recirculation condition compared to the fresh air condition.

Angiogenic gene therapy in patients with nonrevascularizable ischemic heart disease: a phase 2 randomized, controlled trial of AdVEGF121 (AdVEGF121) versus maximum medical treatment

The demonstration that angiogenic growth factors can stimulate new blood vessel growth and restore perfusion in animal models of myocardial ischemia has led to the development of strategies designed for the local production of angiogenic growth factors in patients who are not candidates for conventional revascularization. The results of recent clinical trials of proangiogenesis gene therapy have been disappointing; however, significant limitations in experimental design, in particular in gene transfer strategies, preclude drawing definitive conclusions. In the REVASC study cardiac gene transfer was optimized by direct intramyocardial delivery of a replication-deficient adenovirus-containing vascular endothelial growth factor (AdVEGF121, 4 x 10(10) particle units (p.u.)). Sixty-seven patients with severe angina due to coronary artery disease and no conventional options for revascularization were randomized to AdVEGF121 gene transfer via mini-thoracotomy or continuation of maximal medical treatment. Exercise time to 1 mm ST-segment depression, the predefined primary end-point analysis, was significantly increased in the AdVEGF121 group compared to control at 26 weeks (P=0.026), but not at 12 weeks. As well, total exercise duration and time to moderate angina at weeks 12 and 26, and in angina symptoms as measured by the Canadian Cardiovascular Society Angina Class and Seattle Angina Questionnaire were all improved by VEGF gene transfer (all P-values at 12 and 26 weeks < or =0.001). However, if anything the results of nuclear perfusion imaging favored the control group, although the AdVEGF121 group achieved higher workloads. Overall there was no significant difference in adverse events between the two groups, despite the fact that procedure-related events were seen only in the thoracotomy group. Therefore, administration of AdVEGF121 by direct intramyocardial injections resulted in objective improvement in exercise-induced ischemia in patients with refractory ischemic heart disease.

Phase I trial of Marimastat, a novel matrix metalloproteinase inhibitor, administered orally to patients with advanced lung cancer

PURPOSE

This phase I study was performed to evaluate the safety and pharmacokinetics of escalating doses of Marimastat (British Biotech, Inc, Oxford, United Kingdom) in patients with advanced malignancies and to determine the phase II recommended dose to be used in subsequent studies.

PATIENTS AND METHODS

A standard phase I design was used in this study, in which consecutive groups of three patients were treated with escalating doses of the study drug. Marimastat was administered orally at 25, 50, or 100 mg twice daily to consecutive groups of patients with advanced lung cancer. An additional three patients were added at the highest dose studied (100 mg orally twice daily) to assess whether the inflammatory polyarthitis observed at that dose level can be prevented by a concurrent administration of nonsteroidal antiinflammatory drugs (NSAIDS) and/or low-dose corticosteroids. Blood was drawn for safety monitoring, pharmacokinetic analysis, and plasma levels of metalloproteinase (MMP)-2 and MMP-9 (determined by zymography). A total of 12 patients were studied.

RESULTS

The most significant toxicity at the highest dose studied (100 mg orally twice daily) was a symptomatic inflammatory polyarthritis that persisted for up to 8 weeks after discontinuation of the study drug and was dose-limiting. The estimated plasma elimination half-life of Marimastat was 4 to 5 hours. The mean maximum concentration (Cmax) at a reasonably well-tolerated dose (50 mg orally twice daily) was 196 ng/mL and was reached within 1 to 2 hours (Tmax) after administration. Areas under the curve (AUC) tended to correlate with the dose of Marimastat. Zymographic analysis of peripheral-blood ratios of activated proenzymatic forms of MMP-2 and -9 did not show any consistent patterns of change in MMP levels or in a degree of their activation during the course of treatment.

CONCLUSION

Marimastat was well absorbed from the gastrointestinal tract, with high levels of the study drug detected in plasma within hours after drug administration. Plasma concentrations of Marimastat achieved at dose levels 2 and 3 (50 mg and 100 mg orally twice daily) were substantially higher than those required for MMP inhibition in vitro. The dose-limiting toxicity (DLT) was severe inflammatory polyarthritis, which seemed to be a cumulative toxicity.

Matrix metalloproteinase inhibition as a novel anticancer strategy: a review with special focus on batimastat and marimastat

Matrix metalloproteinases (MMPs) are a homologous family of enzymes that are involved in tissue remodeling and morphogenesis. Collectively, these enzymes are capable of degrading all components of the extracellular matrix, and they play an important role in normal physiologic conditions, such as wound healing and other processes involving tissue remodeling. However, increased activity of these enzymes now has been observed in a number of different pathological conditions, and it has been hypothesized that such increased activity of MMPs might play a role in the pathogenesis of these conditions. Cancer is one such condition; extracellular matrices constitute the principal barrier to tumor growth and spread, and there is growing experimental evidence that malignant tumors utilize MMPs to overcome these barriers. Consequently, inhibitors of MMPs represent an attractive target for a new class of anticancer agents. Marimastat and batimastat are potent broad-spectrum inhibitors of all major MMPs and have been shown to prevent or reduce spread and growth of a number of different malignant tumors in numerous animal models. Both agents are now in advanced clinical testing in a number of different solid tumors in North America and Europe. The purpose of this paper is to review available preclinical and emerging clinical data, using batimastat and marimastat as prototype MMP inhibitors in the cancer area.

Electrophysiologic profile and efficacy of intravenous dofetilide (UK-68,798), a new class III antiarrhythmic drug, in patients with sustained monomorphic ventricular tachycardia. Dofetilide Arrhythmia Study Group

There is increasing evidence that class III antiarrhythmic agents may be superior to class I agents for the long-term treatment of life-threatening ventricular tachyarrhythmias. This open study evaluated the acute electrophysiologic effects, antiarrhythmic efficacy, and safety of different doses of intravenous dofetilide, a new class III drug, in 50 patients with sustained monomorphic ventricular tachycardia inducible by programmed electrical stimulation who had previously been unsuccessfully treated with 0 to 7 (median 3) other drugs. Intravenous dofetilide was administered over 60 minutes at the following dose levels: 1.5, 3.0, 6.0, 9.0, and 15.0 micrograms/kg. Significant class III activity was apparent at doses of 3.0 to 15.0 micrograms/kg, as evidenced by dose-related prolongation of the QTc interval by 13.4% to 14.2%, ventricular effective refractory period by 7.9% to 20.6%, and ventricular functional refractory period by 7.3% to 25.0%. The corresponding mean +/- SD plasma dofetilide concentrations ranged from 1.45 +/- 0.52 to 6.48 +/- 1.31 ng/ml. There was no evidence of reverse use-dependence. At these electrophysiologically active dose levels, intravenous dofetilide suppressed (complete response) or slowed (partial response) inducible ventricular tachycardia in 17 of 41 patients (41%) compared with 0 of 9 patients receiving only 1.5 micrograms/kg. The response rate was fairly uniform among the groups receiving 3.0, 6.0, 9.0, and 15.0 micrograms/kg. Intravenous dofetilide was hemodynamically well tolerated. Torsades de pointes (which was self-limiting) developed in only 1 patient, who was allocated to receive 15.0 micrograms/kg. There were no other proarrhythmic episodes or serious adverse effects. Further evaluation of the therapeutic potential of dofetilide in the management of life-threatening ventricular arrhythmias is justified.

Effect of dofetilide on cardiac repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle

Monophasic action potentials (MAP) were simultaneously recorded from the right ventricular (RV) apex (RVA) and the outflow tract (RVOT) before and after an infusion of dofetilide in 10 patients with documented ventricular tachycardia. After the drug infusion, the MAP duration (MAPd), repolarization time, and corrected QT interval were significantly prolonged during sinus rhythm, RV pacing, and RV extra stimulation. The prolongation of MAPd at 90% repolarization during RV pacing at a cycle length of 500 ms was 31 +/- 6 ms (13%) and 26 +/- 7 ms (11%) at RVA and RVOT, respectively. The ventricular effective refractory period was significantly prolonged by 33 +/- 9 ms (13%) and 22 +/- 7 ms (9%) at driving cycle lengths 600 and 500 ms, respectively. The MAPd shortening with decreasing diastolic time intervals was significantly diminished by dofetilide in early extra beats during RV extra stimulation, suggesting a relatively more pronounced effect of this drug at the early diastolic phase. The dispersion of repolarization, defined as the difference in MAPd between RVA and RVOT, and the activation time were not significantly changed. In conclusion, acute administration of dofetilide in patients with ventricular tachycardia significantly prolonged the time intervals of ventricular repolarization and refractoriness in a parallel fashion, without affecting intraventricular conduction. The effect of dofetilide on MAPd prolongation appeared not to be reverse use-dependent in this study in humans. These results verify the selective class III antiarrhythmic property of dofetilide and warrant further studies in patients.

Influence of oral magnesium supplementation on cardiac events among survivors of an acute myocardial infarction

OBJECTIVE

To investigate the effect of long term oral magnesium treatment on incidence of cardiac events among survivors of an acute myocardial infarction.

DESIGN

Double blind, placebo controlled parallel study in which patients were randomised to treatment or placebo.

SETTING

Two coronary care units and corresponding outpatient clinics.

SUBJECTS

468 survivors of an acute myocardial infarction (289 men and 178 women) aged 31-92.

INTERVENTIONS

One tablet of 15 mmol magnesium hydroxide or placebo daily for one year.

MAIN OUTCOME MEASURES

Incidences of reinfarction, sudden death, and coronary artery bypass grafting in one year.

RESULTS

There was no significant difference between treatment and placebo groups in the incidence of each of the three cardiac events, but when the events were combined and drop outs were excluded from calculations there was a significantly higher incidence of events in the treatment group (56/167 v 33/153; relative risk 1.55 (95% confidence interval 1.07 to 2.25); p = 0.02). When the timing of events was incorporated by means of a Kaplan-Meier plot the treatment group showed a significantly higher incidence of events whether drop outs were included or excluded (p < 0.025).

CONCLUSION

Long term oral treatment with 15 mmol magnesium daily doses not reduce the incidence of cardiac events in survivors of an acute myocardial infarction and, indeed, seems to increase the risk of developing a cardiac event. Consequently, this treatment cannot be recommended as secondary prophylaxis for such patients.

Effects of the class III antiarrhythmic drug dofetilide on ventricular monophasic action potential duration and QT interval dispersion in stable angina pectoris

The effects of intravenous dofetilide on ventricular monophasic action potential duration and effective refractory period at the right ventricular apex and outflow tract were studied in 18 patients (aged 37 to 70 years) with ischemic heart disease. Six patients received low-dose dofetilide as a 3 micrograms/kg loading dose over 15 minutes and a 1.5 micrograms/kg maintenance dose over 45 minutes; 6 received high-dose dofetilide 6 + 3 micrograms/kg and 6 placebo. During atrial pacing at a cycle length of 800 ms high-dose dofetilide prolonged right ventricular apex monophasic action potential duration by 45 ms (16%) and the effective refractory period by 40 ms (16%). At the right ventricular outflow tract, monophasic action potential duration was prolonged by 45 ms (15%) and effective refractory period by 55 ms (21%). During atrial pacing at a cycle length of 500 ms high-dose dofetilide prolonged the right ventricular apex monophasic action potential duration by 40 ms (18%) and the effective refractory period by 43 ms (21%). The right ventricular outflow tract monophasic action potential duration was prolonged by 33 ms (14%) and effective refractory period by 45 ms (21%). Dofetilide produced no increase in the dispersion of repolarization between the 2 sites. During the maintenance infusion QTc prolongation by high-dose dofetilide averaged 43 ms (10%) with no increase of interlead QT dispersion. The effects of dofetilide on QT interval and effective refractory period are shown to be due to a direct effect on action potential duration with no effect on dispersion. No rate dependence of monophasic action potential prolongation was detected at these cycle lengths.

An in vitro study of short-chain fatty acid concentrations, production and absorption in pig (Sus scrofa) colon

1. Short-chain fatty acid concentration was 180 mmol/l in the proximal colon and decreased to 108 mmol/l in the rectum. 2. Fermentation in chymus from different regions of the colon, showed the pattern of end products to reflect the substrate and not the site of the colon. 3. Isolated mucosa from proximal and distal colon had electroneutral sodium absorption of 4.8 +/- 0.2 and 2.9 +/- 0.8 mueq/cm2 hr in bicarbonate free media, which was abolished in the absence of chloride. 4. Electroneutral sodium absorption was enhanced by short-chain fatty acids in the proximal colon and could be described by Michaelis-Menten kinetics with Km 2.0-11 mmol/l and Jm 1.6-3.6 mueq/cm2 hr. In the distal colon the stimulation was smaller and propionate even inhibited sodium absorption. 5. Butyrate was absorbed in the proximal colon, whereas acetate and propionate, and butyrate in the distal colon had a flux ratio of one. 6. Amiloride (5 mmol/l) inhibited sodium absorption and net butyrate absorption.

Pharmacokinetics and metabolism of dofetilide in mouse, rat, dog and man

1. Pharmacokinetics of dofetilide were studied in man, dog, rat and mouse after single i.v. and oral doses of dofetilide or 14C-dofetilide. 2. Dofetilide was absorbed completely in all species. Low metabolic clearance in man resulted in complete bioavailability following oral administration. Higher metabolic clearance in rodents, and to a lesser extent dogs, resulted in decreased bioavailability because of first-pass metabolism. 3. Following i.v. administration, the volume of distribution showed only moderate variation in all species (2.8-6.3 l/kg). High plasma clearance in rodents resulted in short half-life values (mouse 0.32, male rat 0.5 and female rat 1.2 h), whilst lower clearance in dog and man gave longer terminal elimination half-lives (4.6 and 7.6 h respectively). 4. After single i.v. doses of 14C-dofetilide, unchanged drug was the major component excreted in urine of all species with several metabolites also present. 5. Metabolites identified in urine from all species were formed by N-oxidation or N-dealkylation of the tertiary nitrogen atom of dofetilide. 6. After oral and i.v. administration of 14C-dofetilide to man, parent compound was the only detectable component present in plasma and represented 75% of plasma radioactivity. No single metabolite accounted for greater than 5% of plasma radioactivity.

Clinical and electrophysiologic effects of intravenous dofetilide (UK-68,798), a new class III antiarrhythmic drug, in patients with angina pectoris

Dofetilide (UK-68,798) is a new class III antiarrhythmic agent. In animal experiments it selectively prolongs the refractory periods parallel to the action potential duration without any influence on upstroke velocity or conduction parameters. The present double-blind, placebo-controlled study was designed to show the effect of dofetilide on basic electrophysiologic parameters in patients with coronary artery disease. Eighteen patients (aged 31 to 64 years) with symptoms of stable angina pectoris admitted for routine coronary angiography were recruited. They were randomly allocated to receive either placebo or 1 of 2 dose levels of dofetilide intravenously with 6 patients in each group. Paired electrophysiologic variables were compared before and after administration of dofetilide. Both active dose levels produced significant prolongations (p less than 0.05) of 10 to 23% in atrial effective refractory period, 6 to 16% in ventricular effective refractory period and 11 to 15% in ventricular functional refractory period. Atrial functional refractory period was prolonged by 14 to 22% at the high-dose level (p less than 0.05). No effect was observed on conduction parameters (PA, AH, HV, PR or QRS intervals), sinus cycle length or sinus node recovery. The selective prolongation of the refractory periods in both atrium and ventricle, combined with a lack of effect on cardiac conduction parameters, indicates that this drug could be useful in the treatment of both atrial and ventricular reentrant tachyarrhythmias and fibrillation.

A dose-ranging study of UK-68,798, a novel class III anti-arrhythmic agent, in normal volunteers

1. UK-68,798, a novel class III anti-arrhythmic agent was administered intravenously to twelve healthy volunteers in a placebo controlled, double-blind, dose-escalating study. 2. Doses of 5 and 10 micrograms kg-1 of UK-68,798 selectively and significantly prolonged the QT interval, with mean maximum changes of 35 and 107 ms respectively, without affecting other ECG intervals. 3. There were dose-related increases in AUC but clearance (23 l h-1), terminal elimination half-life (8 h) and volume of distribution (245 l) were found to be independent of dose with low levels of intra- and inter-patient variability. 4. UK-68,798 has electrophysiological effects indicative of selective class III anti-arrhythmic activity and merits further assessment in clinical studies.

Pharmacokinetic and pharmacodynamic effects of UK-68,798, a new potential class III antiarrhythmic drug

1. The pharmacokinetic and pharmacodynamic properties of UK-68,798, a novel selective potential class III antiarrhythmic agent, were studied in 18 patients with coronary artery disease. Three groups of four patients received intravenous doses of 1.5, 3.0 and 4.5 micrograms kg-1 respectively over 10 min. 2. UK-68,798 caused a mean increase in electrocardiographic QTc interval of 41, 40 and 81 ms, and in uncorrected QT interval of 36, 52 and 83 ms at the three dose levels. There were no significant effects on heart rate, blood pressure, PR interval and QRS duration. UK-68,798 was well tolerated with no significant adverse effects. 3. A dosing regimen using a loading infusion of two thirds of the total dose over 15 min with the remainder given over the following 45 min in six patients produced stable plasma concentrations and lengthening in QTc during the maintenance infusion. 4. There was a linear correlation between plasma concentration and change in QTc. The drug exhibited first-order kinetics with a mean clearance of 4.7 +/- 1.2 ml min-1 kg-1 and a mean terminal plasma half-life of 9.7 h. 5. UK-68,798 warrants further study as a selective potential Class III antiarrhythmic agent.

Short-chain fatty acids in bowel contents after intestinal surgery

Short-chain fatty acids are produced in the human colon by bacterial fermentation of dietary fibers and other saccharides escaping absorption in the small bowel. Short-chain fatty acid concentrations were determined together with production rates in 6- and 24-h incubations of intestinal outputs from 56 patients with various types of intestinal resections. Concentrations and 6- and 24-h production rates in feces from 9 healthy persons (controls; median +/- SD) were 98.9 +/- 21.4 mmol/L and 17.2 +/- 5.1 and 9.3 +/- 1.5 mmol/L.h, respectively. Colectomized patients with short bowel syndrome had extremely low concentrations (0.8 mmol/L) compared with controls (p less than 10-5), patients with ileostomy (p = 0.003), and ileal reservoirs (p less than 10-5), and showed low 6- and 24-h production rates (1.5 and 0.9 mmol/L.h, respectively; p less than 10-5 vs. controls). Short-chain fatty acids in ileostomic digesta (11.1 mmol/L) were decreased (p = 0.011) compared with outputs from ileal reservoirs (51.5 mmol/L), although production rates were in the same order of magnitude--all below control values (p less than 0.001). Patients partially colectomized and patients with small bowel bypass or short bowel syndrome with preserved colon had normal fecal concentrations with decreased production rates of short-chain fatty acids vs. controls (p less than 0.01). Only minor changes in ratios between individual acids were found. Reciprocal values of short-chain fatty acid concentrations correlated to volumes of outputs from both small intestine (r = 0.86, p less than 10-6) and colon (r = 0.79, p less than 10-6) when results were cumulated. It is concluded that partial resections of colon and the small bowel do not influence the fecal concentration level of short-chain fatty acids as long as colon is not totally resected.

Influence of magnesium substitution therapy on blood lipid composition in patients with ischemic heart disease. A double-blind, placebo controlled study

In a double-blind, placebo-controlled study, 47 patients with ischemic heart disease and acute myocardial infarction were allocated to 3 months' treatment with peroral magnesium (15 mmol/d) or placebo. Before, during, and after treatment, blood samples were taken to determine serum concentrations of cholesterol; triglyceride; high-density, low-density, and very-low-density lipoprotein; apolipoprotein A1 and B; and magnesium. We found a 13% increase in molar ratio of apolipoprotein A1:apolipoprotein B after magnesium treatment, as compared with a 2% increase in the placebo group (for mean differences between changes of the magnesium and the placebo groups). This increase was caused by a decrease in apolipoprotein B concentrations, which were reduced by 15% from 1.44 to 1.23 mmol/L in the magnesium group as compared with a slight increase in the placebo group. Triglyceride, and thereby very-low-density lipoprotein concentrations decreased by 27% after magnesium treatment (from 2.41 to 1.76 mmol/L, and from 1.1 to 0.79 mmol/L, respectively) as compared with much smaller decrements in the placebo group. Likewise, we found tendencies toward an increase in high-density lipoprotein cholesterol and in high-density lipoprotein cholesterol ratio/(low-density lipoprotein cholesterol:very-low-density lipoprotein cholesterol) after magnesium treatment. The observed findings support the hypothesis that magnesium deficiency might be involved in the pathogenesis of ischemic heart disease by altering the blood lipid composition in a way that disposes to atherosclerosis.

The electrophysiological effects of intravenous magnesium on human sinus node, atrioventricular node, atrium, and ventricle

The effects of intravenously (IV) administered magnesium chloride (MgCl) on electrophysiologic and electrocardiographic variables were studied in 13 patients undergoing a routine electrophysiologic assessment for clinical indications. An infusion of 12 mmol of MgCl was given during a 10-min period and relevant electrophysiologic variables were determined before and after the infusion. Serum Mg levels increased from 0.78 +/- 0.03 (mean +/- SEM) before to 1.52 +/- 0.08 ms after the infusion (p less than 0.0001). Magnesium treatment caused a significant prolongation in PR interval (from 151 +/- 8 to 174 +/- 8 ms, p less than 0.001) as well as in QRS duration (from 90 +/- 4 to 101 +/- 6 ms, p less than 0.05). Likewise, intra-atrial (PA) as well as atrioventricular (AV) nodal (AH) conduction times were significantly prolonged (from 33 +/- 3 to 46 +/- 3 ms, p less than 0.01, and from 85 +/- 6 to 94 +/- 6 ms, p less than 0.05, respectively). Mean effective and functional atrial refractory periods increased (from 228 +/- 8 to 256 +/- 10 ms, p less than 0.01 and from 292 +/- 9 to 320 +/- 11 ms, p less than 0.01, respectively), as did mean AV node functional refractory period (from 399 +/- 29 to 422 +/- 27 ms, p less than 0.02). No significant change occurred with regard to sinus node function (as estimated from heart rate, sinus node recovery time, and calculated sinoatrial conduction time) or ventricular refractoriness. It is concluded that IV Mg has several electrophysiologic effects that may be beneficial in the treatment/prevention of supraventricular tachyarrhythmias.

Hemodynamic effects of intravenously administered magnesium on patients with ischemic heart disease

Central hemodynamic parameters were registered by right-side heart catheterization before and after intravenous administration of 12 mmol magnesium chloride (MgCl) in 15 patients with chronic ischemic heart disease and heart failure, New York Heart Association classes II and III. Serum magnesium concentrations increased from 0.76 +/- 0.03 (mean +/- SD) to 1.54 +/- 0.05 mmol/l, which resulted in a reduction in mean arterial as well as pulmonary artery pressure by 10% (p less than 0.0001) and 7% (p less than 0.05), respectively. This reduction was caused by a marked decrease in systemic as well as pulmonary vascular resistance (from 1323 +/- 205 to 1132 +/- 158 dyn.s/cm5, p less than 0.001 and from 156 +/- 73 to 133 +/- 72 dyn.s/cm5 (p less than 0.05). Heart rate, cardiac index, stroke volume index, and stroke work index increased slightly, although these differences did not reach statistical significance. Right and left ventricular filling pressures were not influenced, which indicates that the dilatory effect of magnesium, at the dosages used in the present study, is pronounced only at the arterial side of the vascular bed. The observed hemodynamic effects of the magnesium infusions may be beneficial in the setting of an acute myocardial infarction by reducing left ventricular afterload, which, together with the antiarrhythmic effect of magnesium may contribute to the positive effect of magnesium infusions on mortality in patients with acute myocardial infarction.

Short chain fatty acids in inflammatory bowel disease. The effect of bacterial fermentation of blood

An in vitro faecal incubation system was used to investigate how blood added to faeces influences short chain fatty acid (SCFA) production. The result was a change in SCFA pattern from one largely dominated by acetate and propionate to a pattern less dominated by these two acids but with greater amounts of longer and branched SCFA (butyrate, isobutyrate, valerate and isovalerate). Patients with active ulcerative colitis revealed variable concentrations of SCFA in their individual stool specimens, 66% of the samples being outside the 95% confidence interval set by a control group and without any specific trend. The SCFA concentrations were normal in patients with Crohn's disease of the colon. The study concludes that the changes in SCFA pattern seen elsewhere in studies on ulcerative colitis could be due to bacterial fermentation of blood either in the colon or in the stools after passing. It cautions against using faecal concentrations in this disease without due regard to the phenomenon of dilution or pollution of the colonic chymus by colonic effusion of blood.

Myocardial contractility and performance capacity after magnesium infusions in young healthy persons: a double-blind, placebo-controlled, cross-over study

To evaluate the effect of intravenous magnesium (Mg) treatment on the inotropic state of the heart and maximal work capacity, 9 healthy volunteers were entered in a double-blind, placebo-controlled, cross-over study. Separated by an interval of three weeks, the volunteers were tested twice, each time randomly allocated to receive either an intravenous injection of 10 mmol magnesium chloride dissolved in 100 ml isotonic sodium chloride or placebo of isotonic sodium chloride only. Before and after each infusion myocardial inotropism was evaluated by echocardiography. Mitral-septal distance (MSA) was used as a measure for ejection fraction. On each test day an ergometer bicycle exercise test was performed, and maximal work capacity was calculated. Magnesium treatment reduced the MSA (from 4.2 to 2.9 mm, p = 0.07), while no difference was found after placebo treatment. Likewise, a tendency toward increasing fractional shortening after magnesium treatment was detected, although this difference was not statistically significant (p = 0.1). No difference in maximal work capacity between the magnesium and placebo periods was found. Serum magnesium concentrations and placebo periods was found. Serum magnesium concentrations rose significantly after the infusions (from 0.82 to 1.38 mmol/l, p less than 0.001). It is concluded that intravenous magnesium does not exert a negative inotropic effect on the myocardium as previously stated. On the contrary, we found a tendency toward a positive inotropic effect. However, the observed differences are of borderline statistical significance and a more extended study, employing invasive measurements of cardiac inotropism appears to be necessary.

The effect of intravenous magnesium therapy on serum and urine levels of potassium, calcium, and sodium in patients with ischemic heart disease, with and without acute myocardial infarction

Serum concentrations of magnesium, potassium, calcium, and sodium were determined on admission of 224 patients to the hospital and after 2, 4, and 6 days in hospital; all were admitted to the hospital with suspected acute myocardial infarction (AMI). On admission, the patients were randomly allocated to 48 hours of treatment with magnesium intravenously or placebo. One hundred twenty-three patients had AMI (of whom 53 [43%] were treated with magnesium) and 101 had their suspected AMI disproven (of whom 51 [50%] were treated with magnesium). In a supplementary study, serum and urine levels of magnesium, potassium, calcium, and sodium, together with serum levels of parathyroid hormone, were determined before and after intravenous magnesium treatment in six patients with AMI and six patients with ischemic heart disease but without AMI. In both studies, magnesium therapy was associated with significant alterations in extracellular ion homeostasis. Serum concentrations of potassium decreased during the initial days of hospitalization in the patients treated with placebo, but increased slightly in the patients treated with magnesium infusions. These increments in the serum concentrations of magnesium and potassium correlated significantly. The increase in the serum concentration of potassium after magnesium infusions was due to a reduced renal potassium excretion level (from 71.3 to 49.4 mmol/24 h), indicating the existence of a divalent-monovalent cation exchange mechanism in the nephron. This hypothesis was supported by the observation that renal sodium excretion likewise decreased after magnesium infusions (from 83.2 to 59.2 mmol/24 h). Serum concentration of calcium decreased significantly after magnesium treatment (from 2.35 mmol/L on admission to 2.15 mmol/L after 24 hours in the hospital) in the AMI group, in contrast to the placebo-treated patients, where no significant fluctuations in serum concentration of calcium were detected during the initial six days. This decrease in serum concentration of calcium was due to a marked increase in renal calcium excretion (from 3.43 mmol/24 h before to 6.59 mmol/24 h after magnesium infusion). A correlation between increments in serum magnesium concentration and decrements in serum calcium concentration was detected. No change in serum levels of parathyroid hormone was found before and after magnesium infusions. Both serum and urine levels of magnesium significantly increased after magnesium treatment to levels above the upper normal limits (serum magnesium concentration increased from 0.81 to 1.21 mmol/L, urine magnesium excretion levels from 3.57 to 16.57 mmol/24 h for both serum and urine changes.(ABSTRACT TRUNCATED AT 400 WORDS)

Justification for intravenous magnesium therapy in acute myocardial infarction

Recent studies have shown that patients with acute myocardial infarction (AMI) are magnesium-deficient and develop an additional transient decrease in serum magnesium concentrations (S-Mg c) during the acute phase of the infarct. Animal experiments, as well as studies on humans, have indicated that the acute decrease in S-Mg c as well as a more chronic magnesium (Mg) deficiency state are harmful to the myocardium in the setting of acute ischaemia. This knowledge has led during the last couple of years to the performance of four double-blind placebo controlled studies in which the effect of i.v. magnesium therapy on mortality and incidence of arrhythmias in patients with AMI has been evaluated. Magnesium treatment more than halved the acute mortality and incidence of arrhythmias requiring treatment in three of the four intervention studies. The mechanisms behind the beneficial effect of magnesium therapy are probably multifactorial; a direct depressive effect on the cardiac conducting system; a peripheral dilatory effect on the arteries, reducing the afterload on the myocardium; a reduced infarct size; an ion-stabilizing effect, maintaining stable intra and extracellular concentrations of potassium, sodium and calcium; an improved energy generation in the myocardium; and an inhibitory effect on platelet aggregation. No side-effects were observed in any of the clinical intervention studies. Against this background, the author suggests that i.v. magnesium treatment should be adopted as part of routine practice for patients with acute myocardial infarction.

One-year death rate in 270 patients with suspected acute myocardial infarction, initially treated with intravenous magnesium or placebo

In a double-blind, placebo-controlled study, 273 patients with suspected acute myocardial infarction (AMI) were randomized to receive either 48-h magnesium (Mg) or placebo therapy intravenously, initiated immediately on admission to hospital. We describe the results from a 1-year survey in 270 of the patients, who were available for follow-up. Patients were equally divided: 135 received Mg and 135 received placebo. Mg treatment was associated with a marked reduction in 1-year death rate from 32% in the placebo group to 20% in the Mg group (p = 0.018). If only death from ischemic heart disease is considered, the figures were 28% in the placebo group as opposed to 15% in the Mg group (p = 0.006). This reduction was mainly due to a reduction in mortality during the initial 30 days after inclusion in the study (17% vs. 7%), after which the difference in mortality between the two groups did not reach statistical significance (18% vs. 15%, p = 0.56). The beneficial effect of Mg on mortality was partly linked to a reduced incidence of arrhythmias (27% vs. 16%), and partly to a reduced incidence of infarction (63% vs. 48%) during the initial hospitalization. However, factors unknown to us were also involved, as revealed by a remaining statistically significant partial regression coefficient, when sex, age, cardiovascular history, development of AMI, and development of arrhythmias were considered. It is concluded that intravenous Mg treatment is beneficial to patients with acute ischemic heart disease and should be adopted as part of the routine treatment of these patients.

Bacteriaemia after injection sclerotherapy of oesophageal varices

Thirty consecutive alcoholic patients with biopsy-proven cirrhosis of the liver and oesophageal varices underwent a total of 47 upper intestinal endoscopies. During 31 of the endoscopies paravariceal sclerotherapy of oesophageal varices was performed. Blood cultures were drawn before and after the procedures. Bacteriaemia after endoscopy was detected on seven occasions: six after sclerotherapy and one after endoscopy without sclerotherapy. This difference did not reach statistical significance. The microorganisms cultured belonged to the normal flora of the skin or the oropharynx. Bacteriaemia was transient and had no clinical consequences.

Faecal concentrations and production rates of short chain fatty acids in normal neonates

Changes in intestinal microbial flora are reflected in the faecal concentrations and production rates of short chain fatty acids. However, since no data on the latter are available in neonates, the aim of this study is to provide information on short chain fatty acids in faeces from normal neonates. Faecal samples were collected immediately after birth (meconium) and on the 4th day of life in 13 healthy, full-term neonates. The production capacity was evaluated by a faecal incubation system. Concentrations of short chain fatty acids were low in meconium (11.2 + 3.9 mmol/l (mean +/- SD], equivalent to about 10% of the adult level (p less than 0.01), but increased significantly during the first 4 days of life to 28.4 +/- 20.1 mmol/l (p less than 0.05). The fermentation pattern (i.e. relative composition of different acids) showed differences between adults and neonates, primarily due to a higher proportion of acetate found in the latter. The ratio acetate/propionate/butyrate/other acids was 89/5/5/1 in 4-day-old neonates compared to 65/18/11/6 in adults (p less than 0.001). Our findings correlate well with the postnatal microbial colonization of neonatal colon.

Lactulose detoxifies in vitro short-chain fatty acid production in colonic contents induced by blood: implications for hepatic coma

Short-chain (C2-C6) fatty acids constitute the major anions of colonic contents. Acetate is nontoxic in contrast to C(3)4-C6 fatty acids, which induce coma in animals and have been reported to be of importance in the development of hepatic coma in humans. An in vitro fecal incubation system was used to demonstrate how blood, hemoglobin, albumin, lactulose, galactose, fructose, and glucose influence short-chain fatty acid production in the colon. Blood, hemoglobin, and albumin caused increased production of all C2-C6 fatty acids, with the most pronounced increase (fourfold) in C4-C6 fatty acids. Lactulose was converted to acetate only, as were its monosaccharide components, D-galactose and D-fructose. In assays incubated with blood, the production of C4-C6 fatty acids was completely inhibited by lactulose, D-galactose, D-fructose, and D-glucose, respectively, whereas the production of acetate was increased. Lactulose thus "detoxified" the profile of short-chain fatty acids produced in the presence of blood and proteins, indicating that colonic fermentative bacteria prefer lactulose to blood when both substrates are available. The effect of lactulose in the treatment of hepatic coma caused by episodes of gastrointestinal bleeding may therefore be due to a shift in bacterial metabolism from blood or proteins, or both, to lactulose in the colon, resulting in a simultaneous reduction in toxic nitrogenous and organic acid products.

Degradation of amino acids to short-chain fatty acids in humans. An in vitro study

Short-chain fatty acids (SCFA) originate mainly in the colon through bacterial fermentation of polysaccharides. To test the hypothesis that SCFA may originate from polypeptides as well, the production of these acids from albumin and specific amino acids was examined in a faecal incubation system. Albumin was converted to all C2-C5-fatty acids, whereas amino acids generally were converted to specific SCFA, most often through the combination of a deamination and decarboxylation of the amino acids, although more complex processes also took place. This study indicates that a part of the intestinal SCFA may originate from polypeptides, which apparently are the major source of those SCFA (isobutyrate, valerate, and isovalerate) only found in small amounts in the healthy colon. Moreover, gastrointestinal disease resulting in increased proteinous material in the colon (exudation, mucosal desquamation, bleeding, and so forth) may hypothetically influence SCFA production.

Short-chain fatty acid production from mono- and disaccharides in a fecal incubation system: implications for colonic fermentation of dietary fiber in humans

An in vitro fecal incubation system was used to demonstrate how lactose, lactulose and monosaccharides (mainly constituents of dietary fiber) influence short-chain fatty acid production in colon. Short-chain fatty acids were formed from all mono- and disaccharides tested (except L-glucose): D-glucose, D-galactose, D-fructose, D-mannose, L-rhamnose, D-sorbitol, D-arabinose, D-xylose, D-ribose, D-galacturonate, D-glucuronate, lactose and lactulose. All saccharides increased acetate formation; propionate production was increased from rhamnose, arabinose, xylose, ribose, galacturonic and glucuronic acid, whereas the synthesis of butyrate was elevated in assays incubated with sorbitol, galacturonic and glucuronic acid, and to a lesser degree ribose. Isobutyrate, valerate, isovalerate and hexanoate were produced in increased amounts in assays incubated with albumin, but in fact decreased in many incubations with saccharides. It is speculated that saccharide fermentation always results in formation of acetate, and that the relative production of acetate, propionate and butyrate is related to the monosaccharide composition of dietary fiber available for colonic bacteria. However, the production of isobutyrate, valerate, isovalerate and hexanoate is probably not due to saccharide fermentation, but is rather of polypeptide origin.

Decomposition of wheat bran and ispaghula husk in the stomach and the small intestine of healthy men

Decomposition of dietary fibers in the stomach and small bowel was studied in 13 healthy male volunteers. Liquid control meals were compared with test meals, which in addition contained a source of fiber (wheat bran or ispaghula husk) in random order. Aspirations were collected from the stomach, the proximal jejunum, the mid gut and the terminal ileum. Radiolabeled polyethylene glycol-4000 was used as nonabsorbable water-phase marker, and the formation of free arabinose was used to quantify the hydrolysis of dietary fibers. Ingested fibers, aspirates and urine specimens were analyzed for monosaccharides, either free or fiber-bound, by gas-liquid chromatography. Both types of fiber were hydrolyzed in the stomach, but not in the small bowel. Of ispaghula husk, 1-6% was hydrolyzed, as was 5-8% of wheat bran. Intestinal absorption of free arabinose was 85-93%, but excretion of arabinose in the urine was not greater than after control meals. For further evaluation of gastric hydrolysis six additional healthy male volunteers were studied by serial aspirations from the antral part of the stomach. Hydrolysis was instantaneous for both fibers, and was significantly more pronounced for wheat bran than for ispaghula husk.

Magnesium deficiency in patients with ischemic heart disease with and without acute myocardial infarction uncovered by an intravenous loading test

An intravenous magnesium-loading test with 30 mmol/L of magnesium was used to evaluate the magnesium status in 38 patients with ischemic heart disease (IHD) admitted to the coronary care unit with suspected acute myocardial infarction (AMI), in ten healthy volunteers (control group), and in nine patients with chronic IHD in a stable phase of their disease (chronic IHD group). Sixteen of the patients admitted with acute disease proved to have AMI (AMI group) and 22 did not (non-AMI group). Patients with IHD both with and without AMI retained significantly more magnesium (9.3 and 10.7 mmol/L [22.6 and 26 mg/dL], respectively) than did the control group (1.4 mmol/L [3.4 mg/dL]). This 34% magnesium retention points to a state of magnesium deficiency in patients with IHD. However, since the patients with and without AMI did not differ, the observations do not indicate that AMI is associated with a more severe magnesium deficiency than that found in other IHD patients without AMI. When the patients with IHD were subgrouped according to long-term diuretic treatment, the patients (n = 19) receiving long-term diuretic treatment had a 39% retention of magnesium (11.6 mmol/L [28.2 mg/dL]) compared with a 29% retention (8.7 mmol/L [21.1 mg/dL]) observed in 19 patients who were not receiving long-term diuretic treatment. This observation was not influenced by the presence or absence of AMI. An even higher level of magnesium retention (17.1 mmol/L [41.6 mg/dL] equals 57% retention) was found when investigating patients with chronic ischemic heart disease in a stable phase of their disease. This indicates that patients with IHD may be severely magnesium deficient; that long-term diuretic treatment contributes to this deficiency, but that diuretic treatment per se is not the only cause of this condition.

Differential diagnosis of jaundice: junior staff experience with the Copenhagen pocket chart

Originally published in 1984, the Copenhagen Pocket Chart for early differentiation between causes of jaundice has been tested with success in centres outside Denmark. Using a logistic discrimination model, it estimates probabilities of obstruction and non-obstruction in each case (and provides a further subdivision if desired). Here we evaluate its performance in the hands of young clinicians on a consecutive series of 173 jaundiced patients from two Danish hospitals. The chart performed as well as in the original series: confident diagnoses (probability greater than or equal to 0.80) were assigned to 124 patients; of these 115 proved correct (93%). In 46 patients diagnostic probabilities were less than 0.80, and 3 patients had an unknown cause of jaundice. There were 108 cases in which physician and chart were in agreement, both with a confident diagnosis, and only one of these cases was wrong. In one hospital, contributing 107 cases, each patient was independently examined by a medical student in addition to the physician's examination. Student performance was equally good, practically speaking, in particular when taking the scores on the chart into consideration. As to observer disagreement, the student and the physician typically differed on 0-2 of the chart's 21 items. In no case, however, did this lead to a confident obstructive diagnosis being changed into a confident diagnosis of non-obstruction, or vice versa.

Magnesium infusion reduces the incidence of arrhythmias in acute myocardial infarction. A double-blind placebo-controlled study

In a double-blind placebo-controlled study, 130 patients with verified acute myocardial infarction were given magnesium or placebo treatment intravenously immediately upon admission to hospital. The incidence of arrhythmias requiring treatment during the initial week of hospitalization was registered. Serum magnesium concentrations were increased from 0.7 mmol/l to 1.3 mmol/l as a result of the magnesium infusions. This pharmacologically induced hypermagnesemia resulted in a reduction in the incidence of arrhythmias from 47% in the placebo group to 21% in the magnesium group (p = 0.003). In the magnesium-treated patients, increments in serum concentrations of magnesium and potassium correlated positively (r = 0.47, p less than 0.001). It is concluded that magnesium infusion in the postinfarct period reduces the incidence of supraventricular tachyarrhythmias, and possible pathophysiological mechanisms involved are discussed.

The influence of ispaghula husk and lactulose on the in vivo and the in vitro production capacity of short-chain fatty acids in humans

To evaluate factors influencing the short-chain fatty acid (SCFA) concentrations in stools, three different experiments were performed: faecal concentrations of SCFA at defecation were determined by gas liquid chromatography in nine healthy volunteers on a free diet. SCFAs were 114 +/- 15.0 mmol/l (means +/- SD). The coefficient of variation (CV) of the assay was 4-15%, the intraindividual CV 12-33%, and the interindividual CV 11-29%. On incubation of faeces at 37 degrees C concentrations of SCFA doubled in 6 h and rose fourfold in 72 h. In three volunteers the experiments were extended by adding ispaghula husk or lactulose to the diet for two 14-day periods each; no change in faecal SCFA concentrations was seen, either at defecation or after incubation. When ispaghula husk or lactulose was added to faeces in an in vitro incubation system, the concentrations of SCFA were five times higher than those of controls. We conclude that instant handling of faeces is essential for determinations of SCFA concentrations to obtain interpretable and comparable results; that determination of total SCFA output is of limited value; that addition of fibre to the diet does not influence faecal SCFA concentrations; and that the capacity for SCFA production in faeces is large provided a sufficient amount of substrate is available.

Magnesium and acute myocardial infarction. Transient hypomagnesemia not induced by renal magnesium loss in patients with acute myocardial infarction

Serum magnesium concentrations and the rate of urine magnesium excretion were studied in 24 patients with suspected acute myocardial infarction (AMI). Blood and urine samples were taken on admission, at three-hour intervals for the first 24 hours after admission, and every eight hours for the next 24 hours. Thirteen of the patients were found to have AMI, and the 11 who did not have AMI served as a control. During the first 32 hours, the AMI group had significantly low serum magnesium concentrations. The serum magnesium concentrations were unchanged in the control group. Results of the urine samples disproved our hypothesis that the drop in serum magnesium concentrations was due to an increased renal magnesium loss. These results indicate a magnesium migration associated with AMI, from extracellular to intracellular space.

Intravenous magnesium in acute myocardial infarction

In a double-blind, placebo-controlled study, 273 patients with suspected acute myocardial infarction (AMI) were randomised to receive either magnesium intravenously or placebo immediately on admission to hospital. Of 130 patients with proven AMI 56 received magnesium and 74 received placebo. During the first 4 weeks after treatment mortality was 7% in the magnesium group and 19% in the placebo group. In the magnesium group 21% of patients had arrhythmias that needed treatment, compared with 47% in the placebo group. No adverse effects of intravenous magnesium were observed.