The partition behavior of tributyltin and prediction of environmental fate, persistence and toxicity in aquatic environments

Tributyltin (TBT) is one of the most toxic anthropogenic compounds introduced into the aquatic environment. It has a relatively high affinity for particulate matter, providing a direct and potentially persistence route of entry into benthic sediments. To understand TBT behavior, computational programs are an exceptionally helpful tool for modeling and prediction. EPISuite program was used for evaluation of the prediction data including fate, persistence and toxicity from the partition coefficient values. Without experimental data, the model is useful for prediction but is essentially a default model. A site specific assessment is possible by measuring the partition coefficients and entering the experimental values obtained into the model. This paper describes the results of a study undertaken to determine the partition coefficients and the effect of various parameters on such partition coefficients. The octanol-water partition coefficient (K(ow)) was determined by the OECD shake-flask method, with the logarithm values obtained ranging from 3.9 to 4.9 depending on salinity. The sediment-water partition coefficient (K(d)) was determined by ASTM method of generating Freundlich adsorption isotherms, the obtained values ranged from 88 to 4909 L kg(-1) depending on sediment properties, salinity, pH, and temperature. The experimental partition coefficient K(ow) and K(oc) (calculated from K(d)) were used as input data into the prediction program to provide accurate values for the natural samples in situ. The experimental prediction showed lower toxicity than the default model, but represent actual toxicity and accumulation at the natural site. Moreover, the environmental fate was significantly different when the experimental values and the default values were compared.

Peripheral arterial disease: a growing problem for the internist

The atherothrombotic conditions, coronary artery disease, cerebrovascular disease and peripheral arterial disease (PAD), together account for almost one-half of all deaths in Europe each year; however, perception of the specific risks associated with PAD is generally poor compared with its related conditions. PAD is not just a localised disease--it has serious systemic effects, and affected individuals have a higher risk of serious cardiovascular sequelae or death within 1 year of diagnosis compared with those with coronary artery or cerebrovascular disease. PAD, which currently affects approximately 16% of the general population aged over 55 years, is increasing because of the population aging and the continuing rise in cardiovascular risk factors. The management of PAD is a multi-disciplinary approach, and while this can have its advantages, it can also mean that responsibility for patient care is unclear. Globally, almost one-third of all patients with PAD are under internist care. Internists are ideally placed to identify patients at risk of PAD and initiate prompt risk factor management because of their role in the continued care of elderly patients and those with diabetes, hypertension, dyslipidaemia, and chronic renal disease. Multi-disciplinary guidelines for the clinical management of PAD, based on consensus among international specialists in a number of fields, have been developed to create an informed, unified and proactive approach to the treatment of PAD. They stress the continuity of care, the use of office-based ankle-brachial index testing to aid early diagnosis, and prompt and aggressive risk factor management.

Cutaneous leishmaniasis with boggy induration and simultaneous mucosal disease

A woman had cutaneous, mucosal, and possible visceral leishmaniasis simultaneously. Many of her cutaneous lesions consisted of boggy indurations rather than customary papules, nodules, or ulcers. This unusual case was finally cured after four courses of miltefosine, one course of antimony, and two courses of Ambisome.

Backyard burning

This study was undertaken to determine whether changes had occurred in the numbers of burns that could be related to backyard burning subsequent to the introduction of the council tax throughout Eire for the collection of household refuse. Numbers of patients admitted to our unit who had sustained burns by burning rubbish were recorded prospectively over a period of 12 months. A random control group was taken as three years prior to this and results found by retrospective chart review. Between January and November 2005, 168 patients were admitted to the National Burns Unit, St James's Hospital Dublin, Ireland. Nineteen of these patients sustained flame burns from backyard burning. One hundred and seventy patients were admitted in the comparative period of 2002; Seven of these from backyard burning. The total number of inpatient days for these patients in 2005 (255) was significantly more than in 2002 (68) (p=0.024). The numbers in our study show a marked increase in the number of patients sustaining burns in this manner, and appear to correlate with the introduction of bin charges by a number of county councils around the country last year. This study demonstrates that the introduction of legislation can have an unforeseen adverse affect on the population if not introduced in correlation with appropriate public education. While the introduction of waste charges represents a very necessary move forward in waste disposal in Ireland, public awareness campaigns should be implemented to prevent further such injuries from occurring.

The history of the (Young) AEMI(E) and the EFIM

The European Federation of Internal Medicine (EFIM) was formed in 1996 through a merger between the Association Européenne de Médicine Interne (d' Ensemble) (AEMI(E)) and the Forum of Presidents of National Societies of Internal Medicine (IM). It arose as a result of ideas from Carcassi (Rome/Cagliari) and Merino (Alicante) to transform the largely French-speaking and rather elitist AEMI into a more easily accessible and English-speaking federation of national societies. The founding meeting of the General Assembly of the EFIM took place in May 1996 in Paris. Since then, the EFIM has initiated many activities, some of them originating from the time of the AEMI(E).

Swine models in the design of more effective medical countermeasures against organophosphorus poisoning

Although the three most commonly used large mammal species in the safety assessment of drugs remain the dog, the macaque and the marmoset, swine, especially minipigs, have also been widely used over the years in many toxicological studies. Swine present a number of interesting biological and physiological characteristics. Similarities in skin properties with humans have led to extensive in vitro and in vivo studies. There is a specific interest in cardiovascular research, as well as in anaesthesiology and critical care medicine due to common features of swine and human physiology. Although knowledge of swine brain structure and functions remains incomplete, data does exist. The multiple blood sampling that is necessary in pharmacokinetic and toxicokinetic studies are possible, as well as multiparametric monitoring and interventions with equipment used in human clinical settings. Practicality (handling), scientific (stress reduction) and ethical (invasive monitoring) reasons have led research teams to incorporate anaesthesia into their paradigms which makes the analysis of data increasingly difficult. Although not substantiated by scientific data, the swine appears to have an intermediate position in the scale of public perception between non-human primates and animals commonly referred to as pets (i.e. dogs and cats) and rodents. The benefits of the swine model justify the use of these animals in the design of more effective medical countermeasures against known chemical warfare agents (nerve agents, vesicants and lung damaging agents). Exposure to organophosphorus (OP) pesticides represents a severe health issue in developing countries, while OP intoxication with the more lethal military nerve agents is not only of military concern but also a terrorist threat. Tailoring therapeutic regimens to the reality of OP poisoning is of the utmost importance when little experimental data and sparse human clinical data are available in the decision making process. We will present some of the advantages and disadvantages of the swine model in OP countermeasures elaborating on two examples. First, we will present the issues related to the use of anaesthesia during experimental OP poisoning and second we will show how results from experiments with swine can be integrated into a kinetic-based dynamic model to evaluate oxime efficacy. A better knowledge of OP poisoning in swine (comparative toxicokinetics, pharmacokinetics and biochemistry) is definitely necessary before accepting it as a first choice non-rodent model. However, there exists a large amount of data in the model on anaesthesia and different types of shock favouring their use for evaluation of complex situations such as the anaesthesia of OP poisoned patients and combined injuries.

Endovascular repair of a recurrent aortocaval fistula and anastamotic false aneurysm

Aortocaval fistula (ACF) and false aneurysm are a recognized complication of open abdominal aortic aneurysm (AAA) repair. Untreated they are often fatal. However, open surgical repair of this complication is associated with a high operative mortality and a significant complication rate. Endovascular management using a stent-graft to exclude the false aneurysm and fistula is a technically feasible alternative and confers many advantages over open repair by virtue of its minimally invasive nature. We report the endovascular management of this rare but serious complication of open AAA repair.

Prevalence of methadone injection in three Swiss cities

OBJECTIVE

Intravenous methadone is associated with increased risk of morbidity and mortality. A previous report from a methadone center in Fribourg, Switzerland, found a high prevalence (43%) of patients who injected oral methadone. We therefore wished to assess the prevalence of methadone injection among patients in oral methadone programs in 3 other Swiss cities--Lausanne, Geneva, and La Chaux-de-Fonds.

METHOD

Subjects were randomly selected and interviewed by assistant psychologists who were not on the staff of the study centers. Participation was voluntary and anonymous.

RESULTS

164 patients participated in the study (n = 58 in Lausanne, 52 in Geneva, and 54 in La Chaux-de-Fonds). The prevalence of methadone injection was low (5%) and did not differ significantly between the cities.

DISCUSSION

Less liberal policies cannot explain the lower prevalence of methadone injection in these three centers than in Fribourg. The high prevalence of methadone injection there is probably related to its separate methadone injection program: patients in oral methadone programs may be more likely to injection methadone when other patients authorized to do so.

IN CONCLUSION

Although the 5% prevalence of methadone injection found in the 3 cities surveyed is low, it is not negligible. These results suggest that information on the risks associated with injection of methadone syrup should be provided to all methadone maintenance. This information is especially necessary when maintenance therapy is provided in the same center, or city as injectable methadone maintenance.

Arrhythmias in an athlete: the effect of de-training

A 53 year old athlete with a history of severe palpitations and lightheadedness presented for a second opinion. He was found to exhibit very frequent atrial ectopy, frequent runs of symptomatic atrial tachyarrhythmia, and sinus bradycardia at rest. During exercise testing, his tachyarrhythmias increased in relation to the duration and intensity of exercise. A therapeutic trial of de-training was suggested. As a result, his symptoms completely resolved with a marked reduction in the frequency of atrial arrhythmia. Repeat exercise testing revealed an excellent exercise tolerance with no atrial ectopy. De-training should be considered when athletes present with arrhythmias.

Rapid Absorption of Tumescent Lidocaine above the Clavicles: A Prospective Clinical Study

BACKGROUND

Tumescent local anesthesia has been adapted for surgery of the face and neck, but there are no data regarding drug absorption when tumescent injection is used in this region. The aim of this study was to characterize the changes in plasma lidocaine concentrations over time when a tumescent solution is injected into the subcutaneous tissue of the neck. The study was carried out in human volunteer subjects, and injection of lidocaine to the thighs provided control data.

METHODS

Eight healthy female volunteer subjects were studied twice using a prospective, crossover design. Tumescent lidocaine solution was injected into the subcutaneous tissue of the neck in one session and the thighs in another session. The order of injection was randomized. Blood samples were collected for 14 hours after injection, and the plasma concentration of lidocaine measured. The injected solution consisted of lidocaine 0.1%, NaHCO3 12.5 mEq/L, and epinephrine 1:1,000,000 in normal saline. A standardized dose of lidocaine (7 mg/kg) was used for each injection and no surgical procedure was performed.

RESULTS

All subjects completed the study. Subject weight was 66.1 +/- 12.8 kg, body fat was 29.0 +/- 4.7 percent, and body mass index was 23.8 +/- 3.1 kg/m2. The average time to reach peak lidocaine concentration after neck injection was 5.8 hours, whereas peak lidocaine concentration after thigh injection did not occur until 12.0 hours. This difference of 6.2 hours was highly significant (p = 0.009). The average peak concentration after neck injection was 16 percent greater than that after thigh injection (0.94 microg/ml versus 0.81 microg/ml), with the difference approaching significance (p = 0.06). No adverse reactions were noted.

CONCLUSIONS

Tumescent injection above the clavicles results in a rapid rise in plasma lidocaine concentration when compared with injection to the lower extremities. Toxic symptoms could occur much earlier than expected for lower extremity tumescent anesthesia. In addition, dangerous plasma levels could occur if tumescent anesthesia in the lower extremities is followed by tumescent injection above the clavicles, because the absorption curves would be superimposed.

Systolic blood pressure variability as a risk factor for stroke and cardiovascular mortality in the elderly hypertensive population

OBJECTIVE

To investigate whether baseline systolic blood pressure variability was a risk factor for stroke, cardiovascular mortality or cardiac events during the Syst-Eur trial.

DESIGN

The Syst-Eur study was a randomized, double-blind, placebo-controlled trial, powered to detect differences in stroke rate between participants on active antihypertensive treatment and placebo. Systolic blood pressure variability measurements were made on 744 participants at the start of the trial. Systolic blood pressure variability was calculated over three time frames: 24 h, daytime and night-time. The placebo and active treatment subgroups were analysed separately using an intention-to-treat principle, adjusting for confounding factors using a multiple Cox regression model.

PARTICIPANTS

An elderly hypertensive European population.

MAIN OUTCOME MEASURES

Stroke, cardiac events (fatal and non-fatal heart failure, fatal and non-fatal myocardial infarction and sudden death) and cardiovascular mortality (death attributed to stroke, heart failure, myocardial infarction, sudden death, pulmonary embolus, peripheral vascular disease and aortic dissection).

RESULTS

The risk of stroke increased by 80% (95% confidence interval: 17-176%) for every 5 mmHg increase in night-time systolic blood pressure variability in the placebo group. Risk of cardiovascular mortality and cardiac events was not significantly altered. Daytime variability readings did not predict outcome. Antihypertensive treatment did not affect systolic blood pressure variability over the median 4.4-year follow-up.

CONCLUSION

In the placebo group, but not the active treatment group, increased night-time systolic blood pressure variability on admission to the Syst-Eur trial was an independent risk factor for stroke during the trial.

Isolation of peptides of the brevinin-1 family with potent candidacidal activity from the skin secretions of the frog Rana boylii

The emergence of strains of the human pathogen Candida albicans with resistance to commonly used antibiotics has necessitated a search for new types of antifungal agents. Six peptides with antimicrobial activity were isolated from norepinephrine-stimulated skin secretions from the foothill yellow-legged frog Rana boylii. Brevinin-1BYa (FLPILASLAA10KFGPKLF CLV20TKKC) was particularly potent against C. albicans [minimal inhibitory concentration (MIC) = 3 microm] and also active against Escherichia coli (MIC = 17 microm) and Staphylococcus aureus (MIC = 2 microm), but its therapeutic potential for systemic use is limited by its strong hemolytic activity (HC50 = 4 microm). The single amino acid substitution (Phe12 --> Leu) in brevinin-1BYb resulted in a fourfold lower potency against C. albicans and the additional amino acid substitutions (Lys11 --> Thr, Phe17 --> Leu and Val20 --> Ile) in brevinin-1BYc resulted in a ninefold decrease in activity. Two members of the ranatuerin-2 family and one member of the temporin family were also isolated from the secretions but showed relatively low potency against the three microorganisms tested.

Early detection of malignant process in benign lesions of breast tumor by measurements of changes in structuredness of cytoplasmic matrix in circulating lymphocytes (SCM test) reinduced in vitro by specific tumor antigen

Early detection is crucial for successful treatment of all types of cancer. The specificity and sensitivity of the current methods vary from 50% to 80%. The use of specific tumor antigens and cytometric technology has resulted in the development of a new procedure for the early detection of breast tumors. This new method is reported. The test utilizes static cytometry, which records polarization and intensity changes in fluorescent light emitted from each individual lymphocyte obtained from tumor-bearing patients stimulated by the relevant specific tumor antigen. Using MUC-1/SEC as the specific antigen, we detected breast tumors with 85% specificity and 81% sensitivity in 137 breast tumor-bearing women. A significant linear correlation was found between the SCM test and the conventional classification of relative risk for breast cancer in benign lesions, suggesting that this is a precise method that could be used in mass screening for early detection of breast cancer.

Hematopoietic stem cell transplantation for cardiac and peripheral vascular disease

Recent studies have suggested that marrow and blood hematopoietic stem cells may contribute to nonhematopoietic tissue repair in multiple organ systems. In animal models and more recently in limited human trials, unpurified marrow mononuclear cells and/or subsets of adult hematopoietic stem cells have been reported to contribute to neoangiogenesis. Since the subset of hematopoietic stem cells (HSCs) that are both CD34+ and AC133+ are endothelial cell precursors, clinical trials using autologous AC133+ HSCs isolated with the Miltenyi CLIMACS cell separator and transplanted into patients with ischemic and refractory peripheral vascular or coronary artery disease are being implemented at Northwestern University.

Direct, real-time assessment of dopamine release autoinhibition in the rat caudate-putamen

Inhibition of endogenous dopamine release by photo-released dopamine (i.e., autoinhibition) was characterized in the rat caudate-putamen using combined caged-dopamine photolysis and fast-scan cyclic voltammetry. Coronal brain slices (400 microm thick) were perfused with caged-dopamine (150-200 microM in artificial cerebrospinal fluid). Ultraviolet illumination of increasing duration (25-250 ms, approximately 100 microm beam diameter) was focused at the tip of the recording electrode to uncage increasing amounts of exogenous dopamine at the recording sites (0.5-5 microM); a single biphasic electrical stimulus was delivered 0.1-10 s later to induce endogenous dopamine release. The concentrations of both endogenous and exogenous dopamine were determined using voltammetry, thus enabling determination of concentration-dependent inhibition of the endogenous release by the latter. While unaffected by control ultraviolet illumination, endogenous dopamine release was rapidly inhibited by photo-released dopamine in a concentration-dependent manner. Photo-application of 3-5 microM exogenous dopamine inhibited the endogenous release by 90-100% (electrical stimulus applied 1 s after photolysis initiation), an effect prevented by 2 microM sulpiride. The autoinhibition was dependent on the time between photolysis onset and electrical stimulation. Terminal dopamine autoreceptor stimulation led to robust inhibition of endogenous dopamine release with a latency of approximately 200 ms and effective duration of less than 5 s. The percent autoinhibition was a skewed, U-shaped function of photolysis/electrical stimulation intervals with the peak inhibition at 1 s. This study directly demonstrates that autoreceptor-mediated inhibition of terminal dopamine release in caudate-putamen is designed to provide a rapid, robust, yet short-lasting modulation of terminal dopamine release.

Marginal and internal adaptation of stratified compomer-composite Class II restorations

Different approaches have been proposed to improve the adaptation of Class II restorations, including applying low-elasticity modulus base liners. This in vitro fatigue test (or study) evaluated the influence of the compomer base-lining configuration on restoration adaptation. Direct Class II MOD box-shaped composite restorations with or without base and lining (n=3x8) were placed on intact human third molars with proximal margins 1 mm above or under the CEJ. The compomer (Dyract) was applied as a 1 mm-thick lining or as a base, closing proximo-gingival margins. Marginal adaptation was assessed before and after each phase of mechanical loading (250,000 cycles at 50N, 250,000 cycles at 75N and 500,000 cycles at 100N); internal adaptation was evaluated after test completion. Gold-sputtered resin replicas were observed in the SEM and restoration quality evaluated in percentages of continuity (C) at the margins and within the internal interface after sample section. Mechanical loading did not influence adaptation to enamel, while it adversely affected restoration adaptation to dentin for the full composite and compomer-base restorations (C varied, respectively, from 95.2 to 75.3% and from 98.0 to 10.6%). The internal adaptation quality showed the same general trend, however, with reduced scores of continuity. In this experimental condition, application of a low elasticity modulus layer under the restorative material proved advantageous but the compomer should not contact the gingival margins.

Heart failure in patients admitted to hospital: mortality is still high

BACKGROUND: Two separate cohorts of consecutive patients admitted to hospital with a primary diagnosis of heart failure were studied, the first in 1986 in Rochdale, and the second in 1995 in Brighton. METHODS: We observed the clinical profile, treatment and mortality during hospital admission and reviewed their status at 6 months. There were 132 patients in the Rochdale cohort and 223 in the Brighton cohort. RESULTS: The Rochdale cohort was characterised by a lower mean age and longer hospital stay. Significant differences were also observed in co-morbidity and the use of ACE inhibitors, but hospital mortality was almost identical (25% in Rochdale and 24% in Brighton). A low systolic blood pressure, hyponatraemia, hyperkalaemia and a raised blood urea at presentation were independent adverse prognostic factors. In contrast, prior treatment with ACE inhibitors in patients with congestive cardiac failure led to a more favourable hospital outcome. Age, gender and co-morbidity did not affect mortality apart from patients with acute myocardial infarction. Follow-up of these cohorts showed that mortality of the two groups remained high at 180 days after admission (40% in Rochdale and 39% in Brighton). There were marked differences in the use of ACE inhibitors in survivors, but target doses of ACE inhibitors (enalapril 20 mg/day or equivalent) were only achieved in 31%, despite direct communication between the hospital and primary care physicians. CONCLUSIONS: Although clinical and treatment profiles differed between the two periods studied, the hospital and 6-month mortality of patients with heart failure remained high. More emphasis needs to be given to optimising ACE inhibitor use in primary care.

An approach for high sensitivity detection of breast cancer by analysis of changes in structure of the cytoplasmic matrix of lymphocytes specifically induced by a specific breast tumour antigen (MUC-l/SEC)

An alternative procedure for detection breast cancer was examined based on the observation that lymphocytes re-exposed in vitro to antigenic stimulation will change their intracellular structuredness as measured by polarization of fluorescent light emitted by fluorescein labeled cells (SCM test). The specific antigen MUC-l/SEC was used to elicit such response in lymphocytes of patients with and without breast cancer. Eighty-five samples with breast cancer were tested, of which 72 were correctly diagnosed. Of the 41 controls, 35 were correctly identified as healthy subjects. The sensitivity of the test was 85% and the specificity was 81%. These results suggest a possible valuable method for screening and early detection of breast cancer. The clinical importance of this procedure lies in the ability to screen high-risk populations with higher specificity and sensitivity than any combinations of currently available procedures for breast cancer detection.

Left ventricular aneurysm, aortic valve disease and coronary narrowing in a patient with Hunter's syndrome

Hunter's syndrome (mucopolysaccharidosis type 2, MPS 2) is an inherited disorder of glycosaminoglycan degradation commonly associated with cardiac disease. We present the case of a young man with unusual cardiac manifestations of this syndrome. When mixed aortic valve disease was noted in childhood, other classical features of the milder form of Hunter's syndrome were present. There was no symptomatic or echocardiographic cardiovascular deterioration until age 27 when the patient presented in severe biventricular failure. Investigations demonstrated cardiomegaly and a large apical left ventricular aneurysm. The patient died suddenly soon after this diagnosis. Post mortem examination demonstrated a hypertrophied left ventricle with a 6-cm apical aneurysm. Coronary arterial walls were diffusely thickened but with only mild lumenal stenosis. Mitral and aortic valve disease was also present. There is one previous report of ventricular aneurysm in Hunter's syndrome. Pathophysiological contributions to aneurysm formation may include abnormal coronary flow, the presence of aortic stenosis and abnormal myocardium. This patient's sudden deterioration after a long period of clinical stability reinforces the need for careful follow-up of patients with cardiac manifestations of Hunter's disease.

General medicine in the UK - back stage or centre stage?

Internal medicine, in the UK as well as in the rest of Europe, is in a state of flux. The service has evolved so that the management of acute medical emergencies increasingly dominates the practice of internal medicine, with most outpatient work being dealt with by specialists. As a result, much of the activity of consultant physicians is focused on the delivery of care rather than on the training aspects of internal medicine. Nevertheless, all medical specialists in the UK do pass through a rigorous period of internal medicine during their early training, and there is now increasing emphasis on ensuring that these skills are maintained by practising physicians.

Catastrophic antiphospholipid syndrome: remission following leg amputation in 2 cases

OBJECTIVE

The antiphospholipid syndrome is characterized by venous and arterial thrombotic events that are often recurrent, thrombocytopenia, recurrent fetal loss, and elevated titers of antiphospholipid antibodies. A subtype of patients with a particularly overwhelming clinical picture has been termed catastrophic antiphospholipid syndrome (CAPS). In this report, we present 2 patients who exhibited a similar multisystem disorder associated with gangrenous changes in the lower extremities.

METHODS

Two patients with CAPS are presented, highlighting the impact of this disorder on the patients and the response to various therapeutic modalities.

RESULTS

Both patients had pulmonary, cardiac, cutaneous, and neurologic findings consistent with CAPS. In addition, they had large purulent leg ulcers associated with livedo reticularis. Amputation of the legs in each case induced remission of the systemic illness.

CONCLUSIONS

We believe that infection plays a significant role in the pathogenesis and amplification of the antiphospholipid syndrome. In certain patients, this association probably is mediated via immune mechanisms, which also enhance the genesis of atherosclerosis. After the foci of infection (suppurative leg ulcers) were removed, the underlying illness improved. These case studies provide an opportunity to study the interrelationship between several confounding factors that converge and lead to the development of this autoimmune condition.

Differential time-course profiles of dopamine release and uptake changes induced by three dopamine uptake inhibitors

Using real-time voltammetry, we compared the effects of cocaine (1.0, 3.0, or 10 microM), WIN 35428 (0.1, 0.5, or 2.0 microM), and nomifensine (0.2, 1.0, or 5.0 microM) on electrically evoked dopamine release and uptake in the rat accumbens slice. The time course for onset and offset of the drug effects were determined by perfusing single drug concentration for 30 min, followed by a 60-min washout. Cocaine elicited a rapid, concentration-independent increase in dopamine release and a more gradual, concentration-dependent inhibition of uptake. During washout, uptake inhibition rapidly abated to near baseline values. During the same period, the potentiation of dopamine release exhibited a slower offset for all concentrations and, for 10 microM cocaine, was even greater than that observed during drug perfusion ("rebound" increase). The release rebound was not observed during continuous 90-min perfusion, verifying that cocaine washout per se was a sufficient condition. Selective D1 or D2 antagonists (0.5 microM SCH 39166 or 2 microM sulpiride, respectively) were without effect on cocaine-induced release alterations. WIN 35428 and nomifensine induced similar changes in dopamine kinetics during perfusion. However, in contrast to cocaine, no consistent release rebound was observed during their washout. For 2 microM WIN 38425, washout and continuous perfusion groups exhibited similar changes in dopamine release and uptake. The time-course mismatch between uptake inhibition and DA release potentiation as well as release rebound during washout suggests that altered dopamine release might play a role in behavioral effects of cocaine.

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.

Pharmacodynamics and pharmacokinetics of higher-dose, double-bolus eptifibatide in percutaneous coronary intervention

BACKGROUND

Pharmacodynamics of eptifibatide, a cyclic heptapeptide antagonist of platelet glycoprotein IIb/IIIa, are substantially altered by anticoagulants that chelate calcium, resulting in overestimation ex vivo of the in vivo effects of this agent. We conducted a dose-ranging study to characterize the pharmacodynamics and pharmacokinetics of eptifibatide under physiological conditions.

METHODS AND RESULTS

Patients (n=39) undergoing elective percutaneous coronary intervention were randomly assigned to an eptifibatide bolus followed by an infusion (180-microgram/kg bolus followed by 2 microgram/kg per minute or 250-microgram/kg bolus followed by 3 microgram/kg per minute) for 18 to 24 hours. In a 2:1 ratio, these patients received either a second bolus of eptifibatide (90 microgram/kg or 125 microgram/kg for the initial 180-microgram/kg or 250-microgram/kg groups, respectively) or placebo 30 minutes after the initial bolus. Bleeding times, ex vivo platelet aggregation, receptor occupancy, and plasma eptifibatide levels at baseline and at 1, 2, 3, 4, 6, and 8 hours were evaluated. Platelet inhibition was dose dependent and >80% in all groups by steady state. The single-bolus regimens had a transient loss of inhibition at 1 hour, consistent with rapid distribution and drug elimination. Pharmacokinetic modeling suggested that optimal dosing of eptifibatide would be obtained with a 180-microgram/kg bolus and a 2-microgram/kg per minute infusion followed by a second 180-microgram/kg bolus 10 minutes later.

CONCLUSIONS

A novel higher-dose, double-bolus regimen of eptifibatide in coronary intervention attains and maintains >90% inhibition of platelet aggregation in >90% of patients, providing the pharmacodynamic construct for the design of the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial of adjunctive eptifibatide in coronary stent implantation.

The CICERO system for CAD/CAM fabrication of full-ceramic crowns

The CICERO method of crown fabrication consists of optically digitizing a gypsum die, designing the crown layer buildup, and subsequently pressing, sintering, and milling consecutive layers of a shaded high-strength alumina-based core material, a layer of dentin porcelain, and a final layer of incisal porcelain. Final finishing is performed in the dental laboratory. The CICERO method allows efficient production of all-ceramic restorations without compromising esthetics or function. This article reviews the process involved in the fabrication of a CICERO crown.

The dopamine D2/D3 antagonist DS121 potentiates the effect of cocaine on locomotion and reduces tolerance in cocaine tolerant rats

To explore the significance of dopamine (DA) autoreceptors in cocaine tolerance and cocaine induced locomotor activity rats were treated with saline and cocaine (40 mg/kg per day via osmotic minipump; normal and cocaine tolerant rats, respectively). Injections of DS121 (0-7 mg/kg, i.p.; S(-)-3-(3-(cyanophenyl)-N-n-propylpiperidine), a DA D2/3 and autoreceptor preferring antagonist, either alone (i.e. DS121 + saline injection) or in combination with cocaine (7.5 mg/kg, i.p.) were also given. DS121 (+ saline) increased locomotor activity in both saline and cocaine pump (CP) treated animals. DS121 also potentiated the effect of cocaine on locomotor activity; this effect was greatest in CP (tolerant) animals. It is concluded that DS121 can increase locomotor activity and that this effect is greatest when the DA tone is high, that is when cocaine is present, suggestive of a presynaptic mechanism. Furthermore, because DS121 potentiation of cocaine induced locomotor activity is greatest in tolerant animals it is concluded that supersensitive DA autoreceptors underlie this effect. These data further support our previous data, which show that DA autoreceptors are sensitized after continuous cocaine (minipump) treatment.

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.

Effect of cocaine, nomifensine, GBR 12909 and WIN 35428 on carbon fiber microelectrode sensitivity for voltammetric recording of dopamine

Electrochemical measurements using voltammetry or amperometry at carbon-fiber microelectrodes have been used in vitro and in vivo to examine regulatory mechanisms for the central dopamine system. In many of these experiments, dopamine efflux concentrations under control conditions are determined followed by their alterations in response to a drug treatment. The present study demonstrates that some drugs can affect dopamine measurements, not only by their expected pharmacological action but also by directly altering the microelectrode responsivity. The commonly used reuptake inhibitors GBR 12909 (10 microM) and nomifensine (5 microM) drastically reduce electrode sensitivity and, in the case of nomifensine, increase the time to reach a plateau in response to dopamine boluses (i.e. reduced 'frequency response'). Cocaine (10 microM) and WIN 35428 (2 microM) have negligible effect on these indices. This decrease in sensitivity was found in both nafion and non-nafion coated electrodes. Further, the reduction in sensitivity seen in non-nafion coated electrodes was not prevented by increasing the reversal potential (from +1.0 to +1.3 V) and voltage scan rate (from 350 to 450 V/s). These data suggest that care must be taken when interpreting data from voltammetric or amporometric experiments using carbon electrodes where GBR 12909 or nomifensine are used, especially at high concentrations. Furthermore, wherever possible, direct effects of a drug on electrode sensitivity and frequency response should be determined.

The organization of aggrecan in human articular cartilage. Evidence for age-related changes in the rate of aggregation of newly synthesized molecules

The effect of age on the incorporation of newly synthesized aggrecan into the extracellular matrix of human articular cartilage was investigated. This property was measured in a pulse-chase explant culture system by determining the distribution of radiolabeled molecules ([(35)S]sulfate-labeled) between a nondissociating extract (phosphate-buffered saline), which extracts mainly nonaggregated macromolecules, and a dissociating extract (4 M GnHCl) containing mainly aggrecan that was complexed in situ with hyaluronan. The rate of incorporation of aggrecan into aggregates was much slower in mature cartilage than in tissue obtained from younger individuals. Furthermore, autoradiography showed that in mature cartilage, newly synthesized aggrecan is not transported from the pericellular environment within the first 18 h of chase culture, whereas in immature cartilage, it moves into the intercellular space during the same period, i.e. aggrecan is processed in the extracellular space very differently in young and adult articular cartilage. Experiments were also performed to show that the interaction of link protein with newly synthesized aggrecan depends on the maturity of the G(1) domain of aggrecan. This investigation has shown that the extracellular aggregation of aggrecan in adult human articular cartilage involves a number of intermediate structures. These have not been identified in the very young cartilage obtained from laboratory animals or in porcine and bovine articular cartilage obtained from the abattoir.

Propofol decreases stimulated dopamine release in the rat nucleus accumbens by a mechanism independent of dopamine D2, GABAA and NMDA receptors

Although propofol (2,6-di-isopropylphenol) is a popular i.v. general anaesthetic, it has been suggested to have abuse potential. As many drugs of abuse act preferentially via release of dopamine in the limbic system, we investigated the action of propofol on stimulated dopamine release in the rat nucleus accumbens. Nucleus accumbens slices were superfused (1.6 ml min-1) with artificial cerebrospinal fluid at 32 degrees C. Dopamine release was evoked by electrical stimulation (10 pulses, 0.1 ms, 10 mA, 10 Hz, every 10 min) and monitored by fast cyclic voltammetry. Propofol 100 mumol litre-1 reduced stimulated dopamine release over the 2 h after administration, relative to intralipid controls, to mean 30 (SEM 2)% (P < 0.01). The dopamine D2 receptor antagonist metoclopramide 0.3 mumol litre-1 increased dopamine release but did not block the effect of propofol (38 (3)%). The selective GABAA antagonist bicuculline 24 mumol litre-1 also failed to antagonize the action of propofol (45 (3)%). The NMDA receptor antagonist dextromethorphan 10 mumol litre-1 decreased dopamine release to 57 (6)% (P < 0.01) but failed to block the inhibitory effect of propofol (46 (6)%). Although propofol has been reported to bind to D2, GABAA and NMDA receptors, failure of metoclopramide and bicuculline to block its effects suggests that an agonist action at D2 or GABAA receptors does not mediate the effects of propofol on dopamine release in the rat nucleus accumbens. The lack of effect of dextromethorphan makes an NMDA receptor antagonist action unlikely.

Effect of chronic paroxetine treatment on 5-HT1B and 5-HT1D autoreceptors in rat dorsal raphe nucleus

This study reports the effect of chronic paroxetine (10 mg/kg p.o., 21 days) on 5-HT1B and 5-HT1D autoreceptors controlling stimulated 5-HT efflux in slices of rat dorsal raphe nucleus. Electrically evoked 5-HT (10 pulses, 200 Hz, 0.1 ms, 10 mA) was measured using fast cyclic voltammetry. 5-HT efflux was inhibited by CP 93129 (10 nM-10 microM) and by sumatriptan (1 nM-1 microM) agonists at 5-HT1B and 5-HT1D receptors, respectively. Chronic paroxetine did not, initially, appear to alter the sensitivity of the 5-HT1B autoreceptors to CP 93129. However, when constructed in the presence of WAY 100635 (10 nM) the selective and silent 5-HT1A antagonist, there was a significant (P < 0.001) rightward shift of the CP 93129 concentration-response curve in the paroxetine-treated rats but not in the controls, implying a desensitisation of the 5-HT1B autoreceptor by paroxetine. Chronic paroxetine did not affect the sumatriptan concentration-response curve, even with WAY 100635 present, implying that there was no (de)sensitisation of the 5-HT1D autoreceptor. These data suggest that chronic paroxetine treatment may desensitise 5-HT1B autoreceptors in the dorsal raphe nucleus but that this effect is unmasked only when the dominant 5-HT1A autoreceptor control is antagonised.

Altered sensitivity of dopamine autoreceptors in rat accumbens 1 and 7 days after intermittent or continuous cocaine withdrawal

Using slice preparations, we investigated the effects of chronic cocaine treatment on dopamine autoreceptor sensitivity in the nucleus accumbens core. Cocaine (40 mg/kg/day) was given for 14 days, either by continuous subcutaneous infusion (osmotic minipumps) or single daily injections. One or 7 days after cocaine withdrawal, we used fast scan cyclic voltammetry (10 Hz sampling rate) to measure inhibition of electrically evoked dopamine release by quinpirole (3-300 nM). Continuous cocaine infusion increased quinpirole sensitivity on day 1 of withdrawal, particularly at low concentrations of quinpirole, but this effect was no longer evident by day 7. Intermittent cocaine injections had no effect on day 1 of withdrawal but by day 7 there was a quinpirole subsensitivity. On either withdrawal day, the baseline peak dopamine release or uptake half-life exhibited no treatment group differences. It is suggested that these cocaine dosing regimes cause differential and dynamic changes in dopamine autoreceptor sensitivity during the early withdrawal phase.