A semiautomated method for measuring brain infarct volume

An accurate, reproducible method for determining the infarct volumes of gray matter structures is presented for use with presently available image analysis systems. Areas of stained sections with optical densities above that of a threshold value are automatically recognized and measured. This eliminates the potential error and bias inherent in manually delineating infarcted regions. Moreover, the volume of surviving normal gray matter is determined rather than that of the infarct. This approach minimizes the error that is introduced by edema, which distorts and enlarges the infarcted tissue and surrounding white matter.

Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials

The Standards, Measurements and Testing Programme (formerly BCR) of the European Commission proposed a three-step sequential extraction procedure for sediment analysis, following extensive expert consultations and two interlaboratory studies. This scheme was recently used to certify the extractable trace element contents of a sediment reference material (CRM 601). Although this procedure offers a means to ensure the comparability of data in this field, some difficulties concerning the interlaboratory reproducibility still remain, and a new project is currently being conducted to determine the causes of poor reproducibility in the extraction scheme. The final objective of the project is the certification of new sediment and soil reference materials for their extractable contents of Cd, Cr, Cu, Ni, Pb and Zn. This paper presents the results of a small-scale interlaboratory study, which aimed to test a revised version of the extraction schemes by comparing the original and the modified protocols using the CRM 601 sample. This work offers an improvement to the BCR sequential extraction procedure through intercomparison exercises. This improved procedure will allow the obtaining of CRMs to validate analytical data in the analysis of soils and sediments, and it will also facilitate comparability of data in the European Union.

Methamphetamine neurotoxicity: necrotic and apoptotic mechanisms and relevance to human abuse and treatment

Research into methamphetamine-induced neurotoxicity has experienced a resurgence in recent years. This is due to (1) greater understanding of the mechanisms underlying methamphetamine neurotoxicity, (2) its usefulness as a model for Parkinson's disease and (3) an increased abuse of the substance, especially in the American Mid-West and Japan. It is suggested that the commonly used experimental one-day methamphetamine dosing regimen better models the acute overdose pathologies seen in humans, whereas chronic models are needed to accurately model human long-term abuse. Further, we suggest that these two dosing regimens will result in quite different neurochemical, neuropathological and behavioral outcomes. The relative importance of the dopamine transporter and vesicular monoamine transporter knockout is discussed and insights into oxidative mechanisms are described from observations of nNOS knockout and SOD overexpression. This review not only describes the neuropathologies associated with methamphetamine in rodents, non-human primates and human abusers, but also focuses on the more recent literature associated with reactive oxygen and nitrogen species and their contribution to neuronal death via necrosis and/or apoptosis. The effect of methamphetamine on the mitochondrial membrane potential and electron transport chain and subsequent apoptotic cascades are also emphasized. Finally, we describe potential treatments for methamphetamine abusers with reference to the time after withdrawal. We suggest that potential treatments can be divided into three categories; (1) the prevention of neurotoxicity if recidivism occurs, (2) amelioration of apoptotic cascades that may occur even in the withdrawal period and (3) treatment of the atypical depression associated with withdrawal.

Thrombotic thrombocytopenic purpura associated with clopidogrel

BACKGROUND

The antiplatelet drug clopidogrel is a new thienopyridine derivative whose mechanism of action and chemical structure are similar to those of ticlopidine. The estimated incidence of ticlopidine-associated thrombotic thrombocytopenic purpura is 1 per 1600 to 5000 patients treated, whereas no clopidogrel-associated cases were observed among 20,000 closely monitored patients treated in phase 3 clinical trials and cohort studies. Because of the association between ticlopidine use and thrombotic thrombocytopenic purpura and other adverse effects, clopidogrel has largely replaced ticlopidine in clinical practice. More than 3 million patients have received clopidogrel. We report the clinical and laboratory findings in 11 patients in whom thrombotic thrombocytopenic purpura developed during or soon after treatment with clopidogrel.

METHODS

The 11 patients were identified by active surveillance by the medical directors of blood banks (3 patients), hematologists (6), and the manufacturer of clopidogrel (2).

RESULTS

Ten of the 11 patients received clopidogrel for 14 days or less before the onset of thrombotic thrombocytopenic purpura. Although 10 of the 11 patients had a response to plasma exchange, 2 required 20 or more exchanges before clinical improvement occurred, and 2 had relapses while not receiving clopidogrel. One patient died despite undergoing plasma exchange soon after diagnosis.

CONCLUSIONS

Thrombotic thrombocytopenic purpura can occur after the initiation of clopidogrel therapy, often within the first two weeks of treatment. Physicians should be aware of the possibility of this syndrome when initiating clopidogrel treatment.

Myonecrosis after revascularization procedures

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating > 10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.

Renal artery stenosis: prevalence and associated risk factors in patients undergoing routine cardiac catheterization

The purposes of this study were to determine the prevalence of angiographically significant renal artery stenosis in a patient population referred for diagnostic cardiac catheterization and to develop a model that predicts the highest-risk subset of patients who have significant renal artery narrowing. A prospective validation cohort study was undertaken in a referral-based university hospital. After left ventriculography, abdominal aortography was performed to screen for the presence of renal artery disease. A convenience sample of 1,302 of 1,651 consecutive patients undergoing diagnostic cardiac catheterization were enrolled in the study. Of the 1,302 abdominal aortograms performed, 1,235 (95%) were deemed of adequate quality for the evaluation of renal artery anatomy. Renal artery disease was identified in 30% of the patients. Insignificant renal artery stenosis was found in 187 (15%) and significant (greater than or equal to 50% diameter narrowing) stenosis was found in 188 (15%). Significant unilateral disease was present in 11%, and bilateral disease was present in 4%. By univariable and multivariable logistic regression analysis, the association of both clinically and catheterization-derived variables with renal artery disease was assessed. Multivariable predictors included age, severity of coronary artery disease, congestive heart failure, female gender, and peripheral vascular disease. Hypertension was not an associated variable. These data reveal the previously undetected high prevalence of renal artery disease in patients undergoing cardiac catheterization and provide clinical and angiographic features that assist in predicting its presence.

Visualization of discrete microinfarction after percutaneous coronary intervention associated with mild creatine kinase-MB elevation

BACKGROUND

Mild elevations in creatine kinase-MB (CK-MB) are common after successful percutaneous coronary interventions and are associated with future adverse cardiac events. The mechanism for CK-MB release remains unclear. A new contrast-enhanced MRI technique allows direct visualization of myonecrosis.

METHODS AND RESULTS

Fourteen patients without prior infarction underwent cine and contrast-enhanced MRI after successful coronary stenting; 9 patients had procedure-related CK-MB elevation, and 5 did not (negative controls). The mean age of all patients was 61 years, 36% had diabetes, 43% had multivessel coronary artery disease, and all had a normal ejection fraction. Twelve patients (86%) received an intravenous glycoprotein IIb/IIIa inhibitor; none underwent atherectomy, and all had final TIMI 3 flow. Of the 9 patients with CK-MB elevation, 5 had a minor side branch occlusion during stenting, 2 had transient ECG changes, and none developed Q-waves. The median CK-MB was 21 ng/mL (range, 12 to 93 ng/mL), which is 2.3x the upper limit of normal. Contrast-enhanced MRI demonstrated discrete regions of hyperenhancement within the target vessel perfusion territory in all 9 patients. Only one developed a new wall motion abnormality. The median estimated mass of myonecrosis was 2.0 g (range, 0.7 to 12.2 g), or 1.5% of left ventricular mass (range, 0.4% to 6.0%). Hyperenhancement persisted in 5 of the 6 who underwent a repeat MRI at 3 to 12 months. No control patient had hyperenhancement.

CONCLUSIONS

Contrast-enhanced MRI provides an anatomical correlate to biochemical evidence of procedure-related myocardial injury, despite the lack of ECG changes or wall motion abnormalities. Mild elevation of CK-MB after percutaneous coronary intervention is the result of discrete microinfarction.

Contrast nephrotoxicity: a randomized controlled trial of a nonionic and an ionic radiographic contrast agent

Experimental studies have suggested that nonionic contrast agents are less nephrotoxic than ionic contrast agents. To examine the relative nephrotoxicity of the two types of agents, we randomly assigned 443 patients to receive either iopamidol (nonionic) or diatrizoate (ionic) for cardiac catheterization. The patients were stratified into low-risk (n = 283) or high-risk (n = 160) groups, on the basis of the presence of diabetes mellitus, heart failure, or preexisting renal insufficiency (base-line serum creatinine level, greater than 133 mumol per liter). Serum and urine analyses were performed at base line and 24 and 48 hours after the infusion of contrast material. Nephrotoxicity was defined as an increase in the serum creatinine level within 48 hours of at least 44 mumol per liter. The median maximal rise in the serum creatinine level was 18 mumol per liter in both the diatrizoate group (n = 235) and the iopamidol group (n = 208) (P not significant; power to detect a difference greater than 9 mumol per liter, greater than 90 percent). Creatinine levels increased by at least 44 mumol per liter (0.5 mg per deciliter) in 10.2 percent of the patients receiving diatrizoate and 8.2 percent of the patients receiving iopamidol (P not significant). Among the high-risk patients, creatinine levels increased by at least 44 mumol per liter in 17 percent of the patients in the diatrizoate group, as compared with 15 percent of the patients in the iopamidol group (P not significant). We were unable to demonstrate a difference in the incidence of nephrotoxicity between patients receiving a non-ionic contrast agent and those receiving an ionic contrast agent.

The role of natural history collections in documenting species declines

Efforts to document the decline of extant populations require a historical record of previous occurrences. Natural history museums contain such information for most regions of the world, at least at a coarse spatial scale. Museum collections have been successfully used to analyse declines in a wide range of plants and animals, at spatial scales ranging from single localities to large biotic and political regions. Natural history museum collections, when properly analysed, can be an invaluable tool in documenting changes in biodiversity during the past century.

Balloon aortic valvuloplasty in adults: failure of procedure to improve long-term survival

OBJECTIVES

This study sought to determine the long-term outcome of adult patients undergoing percutaneous balloon aortic valvuloplasty.

BACKGROUND

Percutaneous balloon aortic valvuloplasty has been offered as an alternative to aortic valve replacement for selected patients with valvular aortic stenosis. Although balloon aortic valvuloplasty produces an immediate reduction in the transvalvular aortic gradient, a high incidence of restenosis frequently leads to recurrent symptoms. Therefore, it is unclear whether balloon aortic valvuloplasty impacts on the long-term outcome of these patients.

METHODS

Clinical, hemodynamic and echocardiographic data were collected at baseline in 165 patients undergoing balloon aortic valvuloplasty and examined for their ability to predict long-term outcome.

RESULTS

The median duration follow-up was 3.9 years (range 1 to 6). Ninety-nine percent follow-up was achieved. During this 6-year period, 152 patients (93%) died or underwent aortic valve replacement, and 99 (60%) died of cardiac-related causes. The probability of event-free survival (freedom from death, aortic valve replacement or repeat balloon aortic valvuloplasty) 1, 2 and 3 years after valvuloplasty was 40%, 19% and 6%, respectively. In contrast, the probability of survival 3 years after balloon aortic valvuloplasty in a subset of 42 patients who underwent subsequent aortic valve replacement was 84%. Survival after aortic valvuloplasty was poor regardless of the presenting symptom, but patients with New York Heart Association functional class IV congestive heart failure had events earliest. Univariable predictors of decreased event-free survival were younger age, advanced congestive heart failure symptoms, lower ejection fraction, elevated left ventricular end-diastolic pressure, presence of coronary artery disease and increased left ventricular internal diastolic diameter. Stepwise multivariable logistic regression analysis found that only younger age and a lower left ventricular ejection fraction contributed independent adverse prognostic information (chi-square 14.89, p = 0.0006).

CONCLUSIONS

Long-term event-free and actuarial survival after balloon aortic valvuloplasty is dismal and resembles the natural history of untreated aortic stenosis. Aortic valve replacement may be performed in selected subjects with good results. However, the prognosis for the remainder of patients who are not candidates for aortic valve replacement is particularly poor.

Hypokalaemia and diuretics: an analysis of publications

Published data have been used to define the characteristics of the fall in serum potassium concentration after taking diuretics and the efficacy of the various treatments given to prevent or correct it. The average fall is less after the usual doses of frusemide (about 0.3 mmol/l) than after the usual doses of thiazides (about 0.6 mmol/l) and is little influenced by the dose or duration of treatment. The fall with a given drug is the same in heart failure and hypertension, but the initial serum potassium concentration is higher in heart failure, so that the final value is lower in hypertension. In standard doses potassium supplements are less effective than potassium-retaining diuretics in correcting the hypokalaemia. The relation between the average serum potassium value and the frequency of low values (hypokalaemia) is such that very low values after taking diuretics are unusual in patients with hypertension or heart failure. Hypokalaemia would almost disappear as an important complication of diuretic treatment if it was defined as a value less than 3.0 mmol/l rather than as a value less than 3.5 mmol/l.

Cardiovascular and renal toxicity of a nonionic radiographic contrast agent after cardiac catheterization. A prospective trial

STUDY OBJECTIVE

To determine the incidence of cardiovascular and renal toxicity of a nonionic contrast agent when used for cardiac catheterization, and to assess the value of electrolytes and urinalysis results as predictors of nephropathy induced by a contrast agent.

STUDY DESIGN

Nonrandomized trial using a criterion standard and a cohort analytic study with a 48-hour follow-up.

SETTING

Referral-based university hospital.

PATIENTS

Convenience sample of patients having diagnostic cardiac catheterization. Renal function and clinical status were evaluated at baseline in 1,144 patients; at 24 hours in 1,077 (94%); and at 48 hours in 663 (57%).

INTERVENTIONS

After patients received saline for hydration, coronary angiography and left ventriculography were done with iopamidol (average dose, 203 +/- 56 cc).

MEASUREMENTS AND MAIN RESULTS

The definite and possible incidence of major acute cardiovascular complications from nonionic contrast media was 0.2% and 0.7%, respectively. The mean serum creatinine level increased 11.5 mumol/L from baseline at 24 hours (P less than 0.0001) and 16.8 mumol/L from baseline at 48 hours (P less than 0.0001). Results in a randomly selected training sample were studied to determine predictors of a rise in serum creatinine of 44.2 mumol/L or more. The baseline serum creatinine level and age were significant predictors of renal injury, but hypertension, diabetes mellitus, congestive heart failure, vascular disease, the volume of contrast agent injected or baseline values of urinary variables did not predict nephrotoxicity. In an independent validation sample, only the baseline serum creatinine level was confirmed as a predictor of nephrotoxicity, whereas age was not. A model that predicted contrast-induced nephropathy by the serum creatinine level showed an exponential increase in the risk for nephrotoxicity if the baseline level was 106.1 mumol/L or higher.

CONCLUSIONS

Patients have a small but significant rise in serum creatinine after cardiac catheterization with a nonionic contrast agent. Baseline renal insufficiency is the only confirmed predictor of nonionic contrast-induced nephrotoxicity.

In vivo validation of compensatory enlargement of atherosclerotic coronary arteries

Necropsy examinations and epicardial ultrasound studies have suggested that atherosclerotic coronary arteries undergo compensatory enlargement. This increase in vessel size may be an important mechanism for maintaining myocardial blood flow. It also is of fundamental importance in the angiographic study of coronary disease progression and regression. The purpose of this study was to determine, using intracoronary ultrasound, whether coronary arteries undergo adaptive expansion in vivo. Forty-four consecutive patients were studied (30 men, 14 women; mean age 56 +/- 10 years). Eighty intravascular ultrasound images were analyzed (32 left main, 23 left anterior descending and 25 right coronary arteries). Internal elastic lamina area, a measure of overall vessel size increased as plaque area expanded (r = 0.57, p = 0.0001, SEE = 5.5 mm2). When the left main, left anterior descending and right coronary arteries were examined individually, there continued to be as great or greater positive correlation between internal elastic lamina and plaque area (left anterior descending: r = 0.75, p = 0.0001; right coronary arteries: r = 0.63, p = 0.0007; left main: r = 0.56, p = 0.0009), implying that each of the vessels and all in aggregate underwent adaptive enlargement. When only those vessels with < 30% area stenosis were examined, internal elastic lamina correlated well with plaque area (r = 0.79, and p = 0.0001), and for each 1 mm2 increase in plaque area, internal elastic lamina increased 2.7 mm2. This suggests that arterial enlargement may overcompensate for early atherosclerotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Exacerbation of radiocontrast nephrotoxicity by endothelin receptor antagonism

BACKGROUND

Endothelin is a potent vasoconstrictor that has been implicated in the pathogenesis of radiocontrast nephrotoxicity. Endothelin antagonists may reduce the renal hemodynamic abnormalities following radiocontrast administration.

METHODS

One hundred fifty-eight patients with chronic renal insufficiency [mean serum creatinine +/- SD = 2.7 +/- 1.0 mg/dL (242. 3 to +/- 92.8 micromol/L)] and undergoing cardiac angiography were randomized to receive either a mixed endothelin A and B receptor antagonist, SB 290670, or placebo. All patients received intravenous hydration with 0.45% saline before and after radiocontrast administration. Serum creatinine concentrations were measured at baseline, 24 hours, 48 hours, and 3 to 5 days after radiocontrast administration. The primary end point was the mean change in serum creatinine concentration from baseline at 48 hours; the secondary end point was the incidence of radiocontrast nephrotoxicity, defined as an increase in serum creatinine of > or =0.5 mg/dL (44 micromol/L) or > or = 25% from baseline within 48 hours of radiocontrast administration.

RESULTS

The mean increase in serum creatinine 48 hours after angiography was higher in the SB 209670 group [0.7 +/- 0. 7 mg/dL (63.5 +/- 58.6 micromol/L)] than in the placebo group [0.4 +/- 0.6 mg/dL (33.6 +/- 55.1 micromol/L), P = 0.002]. The incidence of radiocontrast nephrotoxicity was also higher in the SB 209670 group (56%) compared with placebo (29%, P = 0.002). This negative effect of SB 209670 was apparent in both diabetic and nondiabetic patients. Adverse effects, especially hypotension or decreased blood pressure, were more common in the SB 209670 group.

CONCLUSIONS

In patients with chronic renal insufficiency who were undergoing cardiac angiography, endothelin receptor antagonism with SB 209670 and intravenous hydration exacerbate radiocontrast nephrotoxicity compared with hydration alone.

The mago nashi gene is required for the polarisation of the oocyte and the formation of perpendicular axes in Drosophila

BACKGROUND

Drosophila axis formation requires a series of inductive interactions between the oocyte and the somatic follicle cells. Early in oogenesis, Gurken protein, a member of the transforming growth factor alpha family, is produced by the oocyte to induce the adiacent follicle cells to adopt a posterior cell fate. These cells subsequently send an unidentified signal back to the oocyte to induce the formation of a polarised microtubule array that defines the anterior-posterior axis. The polarised microtubules also direct the movement of the nucleus and gurken mRNA from the posterior to the anterior of the oocyte, where Gurken signals a second time to induce the dorsal follicle cells, thereby polarising the dorsal-ventral axis.

RESULTS

In addition to its previously described role in the localisation of oskar mRNA, the mago nashi gene is required in the germ line for the transduction of the polarising signal from the posterior follicle cells. Using a new in vivo marker for microtubules, we show that mago nashi mutant oocytes develop a symmetric microtubule cytoskeleton that leads to the transient localisation of bicoid mRNA to both poles. Furthermore, the oocyte nucleus often fails to migrate to the anterior, causing the second Gurken signal to be sent in the same direction as the first. This results in a novel phenotype in which the anterior of the egg is ventralised and the posterior dorsalised, demonstrating that the migration of the oocyte nucleus determines the relative orientation of the two principal axes of Drosophila. The mago nashi gene is highly conserved from plants to animals, and encodes a protein that is predominantly localised to nuclei.

CONCLUSIONS

The mago nashi gene plays two essential roles in Drosophila axis formation: it is required downstream of the signal from the posterior follicle cells for the polarisation of the oocyte microtubule cytoskeleton, and has a second, independent role in the localisation of oskar mRNA to the posterior of the oocyte.

Sulfation of chondroitin sulfate in human articular cartilage. The effect of age, topographical position, and zone of cartilage on tissue composition

The chondroitin ABC lyase digestion products of normal human femoral condyle articular cartilage and of purified aggrecan were analyzed for their mono- and nonsulfated disaccharide composition. Changes in the total tissue chemistry were most pronounced during the period from birth to 20 years of age, when the -[GlcAbeta,3GalNAc6]- disaccharide content increased from approximately 50% to 85% of the total disaccharide content and there was a concomitant decrease in the content of the 4-sulfated disaccharide. In general, the disaccharide content of the deeper layers of immature cartilage were richer in the 4-sulfated residue than the upper regions of the tissue. As the tissue aged and decreased in thickness, the disaccharide composition became more evenly 6-sulfated. The newly synthesized chondroitin sulfate chains had a similar composition to the endogenous chains and also underwent the same age and zonal changes. The monoclonal antisera 3B3(+) and 2B6(+) were used to immunolocalize the unsaturated 6- and 4-sulfated residues generated at the reducing termini of the chondroitin sulfate chains by digestion with chondroitin ABC lyase, and these analyses indicated that the sulfation pattern at this position did not necessarily reflect the internal disaccharide composition of the chains. In summary, the sulfation pattern of chondroitin sulfate disaccharides from human normal articular cartilage varies with the age of the specimen, the position (topography) on the joint surface, and the zone of cartilage analyzed. Furthermore, these changes in composition are a consequence of both extracellular, post-translational processing of the core protein of aggrecan and changes in the sulfotransferase activity of the chondrocyte.

Evidence that 5-hydroxytryptamine release in rat dorsal raphé nucleus is controlled by 5-HT1A, 5-HT1B and 5-HT1D autoreceptors

Electrically stimulated 5-hydroxytryptamine (5-HT) release was monitored in slices of rat dorsal raphé nucleus (DRN) by fast cyclic voltammetry. Pseudo-single pulse stimulations (5 pulses at 100 Hz) were used to enable the effect of various receptor agonists to be seen without competition from endogenously released transmitter. The selective 5-HT1A receptor agonist, (+)-8-OH-DPAT (1.0 microM) decreased stimulated 5-HT release to 31 +/- 3% of controls. This decrease was inhibited by the 5-HT1A receptor antagonists, (+)-WAY-100135 (1.0 microM) and WAY-100635 (0.1 microM) but not by the 5-HT1D/B antagonist, GR127935 (0.05 microM). The selective 5-HT1B receptor agonist, CP-93129 (0.3 microM) decreased stimulated 5-HT release to 61 +/- 4% of control. This effect was antagonized by the 5-HT1B receptor antagonist, isamoltane (0.5 microM) but not by (+)-WAY-100135. The 5-HT1D agonist, sumatriptan (0.5 microM) decreased stimulated 5-HT release to 52 +/- 2% of controls. This decrease was blocked by GR-127935 but not by WAY-100635. These results suggest that 5-HT release in the rat DRN is under the control of 5-HT1A, 5-HT1B and 5-HT1D autoreceptors.

Actions of tramadol, its enantiomers and principal metabolite, O-desmethyltramadol, on serotonin (5-HT) efflux and uptake in the rat dorsal raphe nucleus

Tramadol is an atypical centrally acting analgesic agent with relatively weak opioid receptor affinity in comparison with its antinociceptive efficacy. Evidence suggests that block of monoamine uptake may contribute to its analgesic actions. Therefore, we have examined the actions of (+/-)-tramadol, (+)-tramadol, (-)-tramadol and O-desmethyltramadol (M1 metabolite) on electrically evoked 5-HT efflux and uptake in the dorsal raphe nucleus (DRN) brain slice, measured by fast cyclic voltammetry. Racemic tramadol and its (+)-enantiomer (both 5 mumol litre-1) significantly blocked DRN 5-HT uptake (both P < 0.05) and increased stimulated 5-HT efflux (P < 0.01 (+/-)-tramadol; P < 0.05 (+)-tramadol). The (-)-enantiomer and metabolite, O-desmethyltramadol, were inactive at the concentration tested (5 mumol litre-1). For both (+/-)-tramadol and the (+)-enantiomer, the action on 5-HT efflux preceded an effect on 5-HT uptake, suggesting that uptake block was not the cause of the increased 5-HT efflux and that tramadol might therefore have a direct 5-HT releasing action. This activity, at clinically relevant concentrations, may help to explain the antinociceptive efficacy of tramadol despite weak mu opioid receptor affinity and adds to evidence that tramadol exerts actions on central monoaminergic systems that may contribute to its analgesic effect.

Mechanisms of balloon angioplasty and directional coronary atherectomy as assessed by intracoronary ultrasound

OBJECTIVE

This study was designed to use intracoronary ultrasound imaging to elucidate the physical effects of balloon angioplasty and directional coronary atherectomy in vivo in humans.

BACKGROUND

The proposed mechanisms of coronary artery interventions such as balloon angioplasty and directional atherectomy are based on animal studies or pathologic findings and these data may not be applicable to living patients. Intracoronary ultrasound findings correlate highly with pathologic results and may allow in vivo assessment of the mechanisms of such interventions in humans.

METHODS

Intracoronary ultrasound imaging was performed in 45 patients after a successful coronary intervention (balloon angioplasty in 30, directional coronary atherectomy in 15). Ultrasound images obtained at the treatment site and at an adjacent angiographically normal references site were analyzed quantitatively for minimal lumen diameter, cross-sectional lumen area, are enclosed by the internal elastic lamina, plaque area (internal elastic lamina area--lumen area) and percent area stenosis (plaque area/internal elastic lamina area). Qualitative analysis included assessment of presence of dissection, plaque composition and plaque topography.

RESULTS

The results of the two procedures were similar with respect to minimal lumen diameter (angioplasty 2.6 +/- 0.5 vs. atherectomy 2.6 +/- 0.3 mm, p = NS), lumen area (0.07 +/- 0.03 vs. 0.07 +/- 0.02 cm2, p = NS) and percent area stenosis (59 +/- 14% vs. 51 +/- 21%, p = NS). However, after angioplasty, the internal elastic lamina area was significantly larger at the treated site than at the reference site (delta = +0.03 +/- 0.04 cm2, p = 0.01). There was no significant difference between the two sites after atherectomy (delta = -0.01 +/- 0.05 cm2, p = NS). In addition, dissection was seen significantly more often after balloon angioplasty than after atherectomy (50% vs. 7%, p less than 0.01). The results were similar when stratified for plaque composition and morphology. These data were confirmed in six additional patients who underwent ultrasound imaging before and after the intervention.

CONCLUSIONS

Thus, the improvement in lumen dimensions after coronary balloon angioplasty is a result of both vessel stretch, demonstrated by a larger internal elastic lamina area at the treated site, and dissection. Both vessel stretch and dissection are uncommon after atherectomy, a finding consistent with plaque removal as the major mechanism for improved lumen area after this procedure.

Impact of intracoronary aspiration thrombectomy during primary angioplasty on left ventricular remodelling in patients with anterior ST elevation myocardial infarction

OBJECTIVE

To evaluate prospectively the impact on left ventricular (LV) remodelling of an intracoronary aspiration thrombectomy device as adjunctive therapy in primary percutaneous coronary intervention (PCI) in patients with anterior ST elevation myocardial infarction (STEMI).

METHODS

76 consecutive patients with anterior STEMI (65.3 (11.2) years, 48 men) were randomly assigned to intracoronary thrombectomy and stent placement (n = 38) or to conventional stenting (n = 38) of the infarct related artery. Each patient underwent transthoracic echocardiography immediately after PCI and at six months. At the time of echocardiographic control, major adverse cardiovascular events (MACE) in terms of death, new onset of myocardial infarction, and hospitalisation for heart failure were also evaluated.

RESULTS

After a successful primary PCI, patients in the thrombectomy group achieved a higher rate of post-procedure myocardial blush grade 3 (36.8% v 13.1%, p = 0.03) and effective ST segment resolution at 90 minutes (81.6% v 55.3%, p = 0.02). Six months after the index intervention, 19 patients (26.8%) developed LV dilatation, defined as an increase in end diastolic volume (EDV) >or= 20%: 15 in the conventional group and four in the thrombectomy group (p = 0.006). Accordingly, at six months patients treated conventionally had significantly higher end systolic volumes (82 (7.7) ml v 75.3 (4.9) ml, p < 0.0001) and EDV (152.5 (18.1) ml v 138.1 (10.7) ml, p < 0.0001) than patients treated with thrombectomy. No differences in cumulative MACE were observed (10.5% in the conventional group v 8.6% in the thrombectomy group, not significant).

CONCLUSION

Compared with conventional stenting, adjunctive aspiration thrombectomy in successful primary PCI seems to be associated with a significantly lower incidence of LV remodelling at six months in patients with anterior STEMI.

Control of dorsal raphé 5-HT function by multiple 5-HT(1) autoreceptors: parallel purposes or pointless plurality?

The serotonergic cells of the dorsal raphé nucleus innervate much of the forebrain and are thought to be involved in the mechanism of action of antidepressants. Dysfunction of these cells might be involved in the neural mechanisms underlying depression and suicide. The traffic in pathways emanating from the dorsal raphé nucleus is controlled by 5-HT(1) autoreceptors. Until recently it was thought that the autoreceptors in the dorsal raphé nucleus were solely of the 5-HT(1A) subtype. In this article, we discuss evidence that the situation is more complex and that multiple 5-HT(1) subtypes govern different aspects of 5-HT function in the dorsal raphé nucleus presenting new therapeutic opportunities.

Rat tendon morphologic and functional changes resulting from soft tissue mobilization

Augmented Soft Tissue Mobilization (ASTM) is a new non-invasive soft tissue mobilization technique which has been used successfully to treat a variety of musculoskeletal disorders. The purpose of this study was to determine the effects of ASTM therapy on the morphological and functional characteristics of enzyme induced injured rat Achilles tendons. Four groups of five rats were allocated as follows: (A) control, (B) tendinitis, (C) tendinitis plus ASTM, and (D) ASTM alone. Collagenase injury was induced, and the surgical site was allowed to heal for 3 wk. ASTM was performed on the Achilles tendon of groups C and D for 3 min on postoperative days 21, 25, 29, and 33 for a total of four treatments. Gait data were gathered prior to each treatment. The Achilles tendons of each group were harvested 1 wk after the last treatment. Specimens were prepared for light and electron microscopy, and immunostaining for type I and type III collagen and fibronectin was performed. Light microscopy showed increased fibroblast proliferation in the tendinitis plus ASTM treatment group. Although healing in rats may not translate directly to healing in humans, the findings of this study suggest that ASTM may promote healing via increased fibroblast recruitment.

Predictive value of dobutamine stress echocardiography for coronary artery disease detection in liver transplant candidates

Patients with obstructive coronary artery disease (CAD) undergoing orthotopic liver transplantation (OLT) are at increased risk of poor outcomes. The accuracy of dobutamine stress echocardiography (DSE) to detect obstructive CAD is not well established in this population. We retrospectively identified patients with end-stage liver disease who underwent both DSE and coronary angiography as part of risk stratification prior to OLT. One hundred and five patients had both DSE and angiography, of whom 14 had known CAD and 27 failed to reach target heart rate during DSE. Among the remaining 64 patients (45 men; average age 61 +/- 8 years) DSE had a low sensitivity (13%), high specificity (85%), low positive predictive value (PPV) (22%) and intermediate negative predictive value (NPV) (75%) for obstructive CAD. DSE as a screening test for obstructive CAD in OLT candidates has a poor sensitivity. The frequent chronotropic incompetence and low sensitivity in patients who achieve target heart rate, even in those with multiple cardiovascular disease risk factors, suggest that alternative or additional methods of risk stratification are necessary.

450 million years of hemostasis

In mammalian blood coagulation, five proteases (factor VII [FVII]; factor IX [FIX]; factor X [FX]; protein C [PC] and prothrombin [PT]) act with five cofactors (tissue factor [TF]; factor V [FV]; factor VIII [FVIII]; thrombomodulin and protein S) to control the generation of fibrin. Biochemical evidence, molecular cloning data and comparative sequence analysis support the existence of all components of this network in all jawed vertebrates, and strongly suggest that it evolved before the divergence of teleosts over 430 million years ago. Phylogenetic analysis of the amino acid sequences of the Gla-EGF1-EGF2-SP domain serine proteases (FVII, FIX, FX, PC) and the A domain-containing cofactors (FV and FVIII) strongly supports the evolution of the blood coagulation network through two rounds of gene duplication, and supports the hypothesis that vertebrate evolution benefited from two global genome duplications. The jawless vertebrates (hagfish and lamprey) that diverged over 450 million years ago have a blood coagulation network involving TF, PT and fibrinogen. Preliminary evidence indicates that they may have a smaller complement of Gla-EGF1-EGF2-SP domain proteins, suggesting the existence of a 'primitive' coagulation system in jawless vertebrates.

Thrombotic thrombocytopenic purpura associated with ticlopidine in the setting of coronary artery stents and stroke prevention

BACKGROUND

One of the most unusual causes of thrombotic thrombocytopenic purpura (TTP), a life-threatening disease, is ticlopidine hydrochloride, an antiplatelet agent used to prevent strokes in high-risk populations or following coronary artery stent placement. Recently, Hoffman-LaRoche Pharmaceuticals, following reports of 20 deaths from ticlopidine-associated TTP, updated the information about the hematologic adverse effects of the drug.

OBJECTIVES

To review our recent findings on ticlopidine-associated hematologic toxic effects, which served as the impetus for the revised warnings, and to discuss the implications of these findings.

METHODS

Data were obtained from the Food and Drug Administration's MedWatch program, published phase 3 clinical trials and case reports, hematologists, and plasmapheresis centers.

RESULTS

No cases of TTP have been reported in phase 3 ticlopidine trials. In contrast, postmarketing surveillance has identified serious adverse drug reactions to ticlopidine, resulting in 259 deaths, with TTP accounting for 40 of these deaths. Detailed information was available on 98 cases of ticlopidine-associated TTP. Compared with 42 patients in the coronary artery stent setting, 56 patients with ticlopidine-associated TTP in the stroke prevention setting were more likely to be women (62.5% vs 28.6%; P = .01). Before the onset of TTP in patients receiving stroke prevention therapy and patients with stent placement, ticlopidine had been used for less than 2 weeks in 5.4% and 2.4%, between 2 and 3 weeks in 17.9% and 21.4%, between 3 and 4 weeks in 30.4% and 38.1%, and between 4 and 12 weeks in 46.4% and 38.1%, respectively. Death occurred in almost 60% of all patients not receiving plasmapheresis compared with 21.9% of patients receiving plasmapheresis for stroke prevention and 14.3% of patients receiving plasmapheresis in the stent setting.

CONCLUSIONS

Use of ticlopidine requires frequent physician visits and laboratory tests for at least 3 months in the stroke prevention setting, while, with short-term use in the coronary artery stent setting, adverse events are less likely to occur. These factors, as well as competition from clopidogrel bisulfate, a new antiplatelet agent, potentially limit the feasibility of ticlopidine as a stroke prevention agent, while having less impact on its use following coronary artery stent placement.