Effect of liver impairment on the pharmacokinetics of tolcapone and its metabolites

OBJECTIVE

To assess the effect of liver impairment on the pharmacokinetics of tolcapone and to derive appropriate dose recommendations for patients with this disease who are undergoing treatment for Parkinson's disease.

STUDY DESIGN

In an open, two-way crossover study, 16 patients with moderate liver disease (eight with cirrhotic and eight with noncirrhotic liver disease) and eight healthy subjects received an oral dose of 200 mg tolcapone and an intravenous dose of 50 mg tolcapone on separate occasions. The concentrations of total and unbound tolcapone and its three major metabolites (tolcapone glucuronide, carboxylic acid, and 3-O-methyl metabolite) were assessed in plasma and urine.

RESULTS

On the basis of total drug concentration, the differences in tolcapone pharmacokinetics between the groups were small. However, lower clearance and volume of distribution of unbound drug were found among patients with cirrhosis than among control subjects. Plasma concentration of the pharmacologically inactive glucuronide metabolite was increased among patients with cirrhosis.

CONCLUSIONS

Half of the recommended dosage of tolcapone should be administered to patients with cirrhosis of the liver to maintain the target steady-state concentration of unbound drug and to avoid accumulation of tolcapone glucuronide. Our data did not indicate a requirement for dosage adjustment in the presence of moderate chronic hepatitis.

Gastrografin as a gastrointestinal contrast agent in the Greek tortoise (Testudo hermanni)

Eighteen Greek tortoises (Testudo hermanni), divided into three groups, were kept at three different average ambient temperatures. Gastrografin was administered to all individuals by orogastric tube at a dosage of 1 ml/130 g body weight. The partial and total transit times were recorded by means of radiographs taken immediately postadministration and at 20, 40, 60, 90, 120, and 150 min and 3, 4, 6, 8, 12, 24, 48, 72, and 96 hr postadministration. Mean total transit times were 2.6 hr (range 1.5-4.0 hr) at 30.6 degrees C, 6.6 hr (range 3.0-8.0 hr) at 21.5 degrees C, and 17.3 hr (range 8.0-24.0 hr) at 15.2 degrees C. These transit times allow a radiologic diagnosis within a relatively short period, especially compared with contrast studies performed with barium sulfate. The visualization of the intestinal tract is good with Gastrografin; however, intestinal mucosal detail was not completely satisfactory.

[Prognostic significance of analysis of heart rate variability inpatients with dilated cardiomyopathy]

Sudden cardiac death is frequent in patients with dilated cardiomyopathy. To assess the risk of an arrhythmic event is still difficult. Here the analysis of the heart rate variability offers new possibilities.

METHOD

25 patients (18 males, 7 females, age 53 +/- 9 yrs) with dilated cardiomyopathy were included in the study. Analysis of heart rate variability assessed by time- and frequency-domain measures was determined from Holter recording. The mean follow-up was 18 +/- 5 months.

RESULTS

6 patients died (5 of sudden cardiac death, 1 of heart failure), 1 patient with an implanted defibrillator received an adequate shock. Parameters influenced by low- and mid-frequent oscillations of the heart rate were significantly lower in patients who died suddenly or had adequate shocks. The best predictive parameter was the s.d.RR: all patients with an s.d.RR < 50 ms had lethal arrhythmias whereas the s.d.RR of the surviving patients was > or = 50 ms. No significant difference was found or high frequency parameters, which are mainly influenced by parasympathetic activity.

CONCLUSION

The analysis of heart rate variability is of prognostic relevance in patients with dilated cardiomyopathy. Especially the s.d.RR is able to identify patients with a high risk of a sudden cardiac death.

Patient choice in diabetes education curriculum. Nutritional versus standard content for type 2 diabetes

OBJECTIVE

To examine the effects of patient choice between two education curriculums that emphasized either the standard or nutritional management of type 2 diabetes on class attendance and other outcomes among a mostly Hispanic patient population.

RESEARCH DESIGN AND METHODS

A total of 596 patients with type 2 diabetes were randomly assigned to either a choice or no choice condition. Patients in the choice condition were allowed to choose their curriculum, while patients in the no choice condition were randomly assigned to one of the two curriculums. Outcomes were assessed at baseline and at a 6-month follow-up.

RESULTS

When given a choice, patients chose the nutrition curriculum almost four times more frequently than the standard curriculum. Contrary to our hypothesis, however, patients who had a choice did not significantly increase their attendance rates or demonstrate improvements in other diabetes outcomes compared with patients who were randomly assigned to the two curriculums. Patients in the nutrition curriculum had significantly lower serum cholesterol at a 6-month follow-up, whereas patients in the standard curriculum had significant improvements in glycemic control. Of the randomized patients, 30% never attended any classes; the most frequently cited reasons for nonattendance were socioeconomic. Hispanic patients, however, were just as likely as non-Hispanic patients to attend classes and participate at the follow-up. Patients who attended all five classes of either curriculum significantly increased their diabetes knowledge, gained less weight, and reported improved physical functioning compared with patients who did not attend any classes.

CONCLUSIONS

Although providing patients with a choice in curriculums at the introductory level did not improve outcomes, differential improvements were noted between patients who attended curriculums with different content emphasis. We suggest that diabetes education programs should provide the opportunity for long-term, repetitive contacts to expand on the modest gains achieved at the introductory level, as well as provide more options to match individual needs and interests and to address socioeconomic barriers to participation.

Bacterial leakage into and from prefabricated screw-retained implant-borne crowns in vitro

A mean gap of less than 4 microm following laboratory procedures and continuous loading was demonstrated in prefabricated crowns of the Ha-Ti implant system in earlier studies. The clinical relevance of such high precision in maintaining inflammation free marginal mucosa is yet to be determined. In this present investigation, the complete assembly of Ha-Ti implants including prefabricated screw-retained crowns was tested for bacterial leakage under controlled conditions in vitro. The gaps were shown not to be a barrier for Staphylococcus aureus which were used as test bacteria. Bacterial leakage through these gaps from the environment to the interior of the assembly and vice versa was observed within 24-120 h. The main path of bacterial penetration was possibly found to be through the transversal screw hole and not through the marginal gap of the prefabricated crowns.

Hypothermia as cerebroprotective measure. Experimental hypoxic exposure of brain slices and clinical application in critically reduced cerebral perfusion pressure

An in vitro human neocortical and rodent hippocampus brain slice technique was used under repeated hypoxia to investigate the cerebroprotective effect of hypothermia. As a hallmark of the neuronal hypoxic reaction anoxic terminal negativity (ATN) was registered to test whether hypothermia delays the onset of ATN. The experiments clearly confirm an assumed protective effect of hypothermia in vitro and in vivo and give for the first time evidence of the lack of the protective effect of hypothermia once hypoxia has occurred under normothermic conditions, probably by a critical depletion of cellular ATP-stores. In patients with severe traumatic brain injury and critically low cerebral perfusion pressure mild hypothermia is able to improve clinical outcome.

Endogenous nitric oxide and the pulmonary microvasculature in healthy sheep and during systemic inflammation

Nitric oxide (NO) influences microvascular integrity. NO synthase inhibitors are regarded as therapeutic options, but their impact on the pulmonary microvasculature is not well defined. We studied the microvascular effects of the nonselective NO synthase inhibitor N(omega)-nitro L-arginine methylester (L-NAME) in healthy sheep and during systemic inflammation. Permeability analysis was performed in 30 adult ewes with chronic lung lymph fistulas and pulmonary venous occluders. Experiment 1: 20 sheep received Escherichia coli endotoxin (lipopolysaccharide, 10 ng/kg/min) for 32 h. After 24 h of endotoxemia, 10 sheep were given L-NAME (25 mg/kg), and 10 sheep received NaCl 0.9%. Experiment 2: six sheep were treated with L-NAME (25 mg/kg), and four animals received NaCl 0.9%. Endotoxin induced a phasic pulmonary microvascular response with early transiently increased endothelial permeability at 4 h and late normalization of microvascular integrity to large molecules after 24 h. At that time systemic vasodilation had occurred. L-NAME raised pulmonary artery pressure and pulmonary vascular resistance index without signs of increased permeability in either experiment. NO is involved in vascular tone in healthy sheep and during systemic inflammation, but it does not seem to play a role in the integrity of the pulmonary microvascular barrier function to large molecules.

Models for the longitudinal genetic analysis of same-age twins: application to HDL cholesterol

Models are presented for the analysis of longitudinal data from same-age twins which permit the exploration of a remarkably diverse array of alternative explanations for continuity and change during development. Data of this type permit the detection of new sources of genetic or environmental covariation during development that are not expressed at earlier ages and, because they include the effects of age-specific genes, the resulting heritability estimates are more reliable than those obtained from relatives who differ in age. The proposed models were applied to measurements of HDL cholesterol obtained on 81 pairs of monozygotic (MZ) twins and 69 dizygotic (DZ) pairs at 11, 12.5 and 14 years of age. All three MZ co-twin correlations were substantially higher than the self correlations across occasions, suggesting that new sources of genetic or environmental covariation must be expressed during early adolescence. This interpretation was confirmed by analysis of the full covariance matrices which showed that only models which assumed the expression of new or age-specific genes could explain the observed pattern of covariation. Because they include the effects of age-specific genes, the resulting heritabilities (0.80-0.83) were substantially higher than many previous estimates.

DNA analysis of temperate bacteriophage Aa(phi)23 isolated from actinobacillus actinomycetemcomitans

The DNA of the temperate bacteriophage Aaphi23 isolated from the oral bacterium Actinobacillus actinomycetemcomitans was examined structurally both in the phage head and in the prophage. The DNA in phage particles comprises 44 kb linear molecules with a terminal redundancy of 1.6 kb, which represent circular permutations. Thus, DNA is packaged into phage heads by the headful mechanism. The Aaphi23 prophage is integrated into the host chromosome.

A case of severe cerebral trauma in a patient under chronic treatment with cyclosporine A

A case of severe cerebral head injury in a child, chronically treated with cyclosporine A after orthotopic liver transplantation, is presented. The initial Glasgow Coma Scale score after the motor vehicle accident was 3, and computed tomography showed multiple sites of intracerebral bleeding, an epidural hematoma, and signs of perifocal edema. Although these lesions are normally associated with a poor outcome, the child recovered unexpectedly well. In brain injury, a lucid interval can be followed by secondary neurologic deterioration due to a loss of high-energy metabolites, a release of neurotransmitters, and an increase in intracellular Ca2+. These events finally led to cell damage in the penumbra of an ischemic infarction. Among other drugs, immunosuppressants such as cyclosporine A have been shown to exhibit neuroprotective properties in experimental models if given during this time interval of secondary neurologic deterioration. Although human data on these effects are still lacking, we conclude that neuroprotective actions of cyclosporine A may have been involved in the favorable outcome in this 14-year-old boy.

Inhaled prostaglandin E1 for treatment of acute lung injury in severe multiple organ failure

Acute lung injury is characterized by hypoxemia due to pulmonary ventilation/perfusion-mismatching. I.v. administered prostaglandin E1 (PGE1), a vasodilator with a high pulmonary clearance, has been studied in acute lung injury. Inhalation of the vasodilators nitric oxide and prostacyclin improved oxygenation by selective dilation of the pulmonary vasculature in ventilated lung areas. In the present study, PGE1 inhalation was used for treatment of acute lung injury. Fifteen patients with acute lung injury defined as PaO2/fraction of inspired oxygen (FIO2) <160 mm Hg were treated with PGE1 inhalation in addition to standard intensive care. The drug was continuously delivered via a pneumatic nebulizer. Acute physiology and chronic health evaluation system II and multiple organ failure scores were (mean +/- SEM) 33 +/- 2 and 10 +/- 0.3, respectively. Inhaled PGE1 was administered for 103 +/- 17 h at a dose of 41 +/- 2 microg/h. The PaO2/FIO2 ratio increased from 105 +/- 9 to 160 +/- 17 mm Hg (P < 0.05) and to 189 +/- 25 mm Hg (P < 0.05) after 4 h and 24 h, respectively. PGE1 inhalation decreases in mean pulmonary artery pressure and central venous pressure were not statistically significant. Mean arterial pressure, pulmonary capillary wedge pressure, cardiac output, and heart rate remained unchanged. Intensive care unit mortality was 40%. The present data suggest that inhaled PGE1 is an effective therapeutic option for improving oxygenation in patients with acute lung injury. Whether inhaled PGE1 will increase survival in acute lung injury should be investigated in a controlled prospective trial.

IMPLICATIONS

In patients with severe acute lung injury and multiple organ failure, inhaled prostaglandin E1 improved oxygenation and decreased venous admixture without affecting systemic hemodynamic variables. Controlled clinical trials are warranted.

Animal pharmacokinetics and interspecies scaling of Ro 25-6833 and related (lactamylvinyl)cephalosporins

From a series of six (lactamylvinyl)cephalosporins, candidates for clinical evaluation were selected on the basis of their kinetic profile in animals and predicted pharmacokinetics in man. Exploratory pharmacokinetic studies with Ro 25-6833 and five related cephalosporins were performed following intravenous administration to rats, dogs, and cynomolgus monkeys. All compounds were characterized by a high protein binding in rat, monkey, and human plasma (unbound fraction < or = 5%), whereas in dog plasma, protein binding was markedly lower. Accordingly, for most compounds, clearance was highest in dogs, and lowest in monkeys. Comparison of the renal clearance of unbound drug with creatinine clearance suggests a renal elimination of Ro 25-6833 by glomerular filtration in both rats and dogs (urinary excretion in monkey was not determined due to drug instability in monkey urine). All other compounds showed different renal excretion mechanisms in rats and dogs, thus making the validity of allometric scaling questionable. Unbound clearances in man were predicted by allometric scaling (Ro 25-6833 only) and by a correlation analysis of cephalosporin pharmacokinetics in monkey and man. Limitations of both methods are discussed. When Ro 25-6833 was later studied in man, the predicted pharmacokinetic data in man from both approaches were found to be in good agreement with the observed values.

Comparison of antiplatelet effects of aspirin, ticlopidine, or their combination after stent implantation

BACKGROUND

This study was performed to analyze the influence of either aspirin, ticlopidine, or their combination on platelet activation and aggregation parameters after stent implantation.

METHODS AND RESULTS

Sixty-one patients with successful implantation of a single Palmaz-Schatz stent in a native coronary artery were randomly assigned to either group A (aspirin 300 mg/d+ticlopidine 2X250 mg/d), group B (ticlopidine 2X250 mg/d), or group C (aspirin 300 mg/d). Platelet activation was evaluated on days 1, 7, and 14 by flow cytometry measurement of expression of CD62p (p-selectin) and the binding of fibrinogen to the platelet surface glycoprotein IIb/IIIa receptor. Platelet aggregation was induced by addition of ADP or collagen. Differences between treatment groups were compared by ANOVA. Between days 1 and 14, we observed a significant decrease in collagen-induced platelet aggregation in group A (62.2+/-2.5% versus 36.9+/-3.1%), whereas an increase was seen in group B (58.3+/-2.5% versus 67.7+/-3.2%) and no change was seen in group C (P<.0001). The ADP-induced aggregation declined significantly in group A (74.7+/-1.4% versus 55.3+/-2.6%), whereas a delayed reduction was seen in group B (72.0+/-3.0% versus 52.6+/-4.2%) and no change was seen in group C (P=.0017). The CD62p expression declined significantly in groups A (68.2+/-2.7% versus 41.3+/-2.7%) and B (64.8+/-2.9% versus 39.3+/-3.5%) but not in group C (P<.0001). Moreover, the fibrinogen binding decreased significantly in group A (61.0+/-4.3% versus 36.3+/-4.2%) and with delay in group B (58.3+/-2.2% versus 39.4+/-3.0%), whereas no alterations were seen in group C (P=.012).

CONCLUSIONS

Our results demonstrate synergistic and accelerated platelet inhibitory effects of ticlopidine plus aspirin in patients after stent implantation compared with a monotherapy with either ticlopidine or aspirin alone.

The 5-HT transporter gene-linked polymorphic region (5-HTTLPR) in evolutionary perspective: alternative biallelic variation in rhesus monkeys. Rapid communication

By conferring allele-specific transcriptional activity on the 5-HT transporter gene promoter in humans, the 5-HT transporter gene-linked polymorphic region (5-HTTLPR) influences a constellation of personality traits related to anxiety and increases the risk for neurodevelopmental, neurodegenerative, and psychiatric disorders. Here we have analyzed the presence and variability of the 5-HTTLPR in several species of primates including humans, and other mammals. PCR, Southern blot, and sequence analyses of the 5-HT transporter gene's 5'-flanking region in different mammalian species confirmed the presence of the 5-HTTLPR in platyrrhini and catarrhini (hominoids, cercopithecoids) but not in prosimian primates and other mammals. Since the 5-HTTLPR is unique to humans and simian primates, a progenitor 5-HTTLPR sequence may have been introduced into the genome some 40 Mio, years ago. In humans the majority of alleles are composed of either 14 or 16 repeat elements, while alleles with 18 or 20 repeat elements are rare. In contrast, great apes including orang-utan, gorilla, and chimpanzee display a high prevalence of alleles with 18 and 20 repeat elements. In hominoids all alleles originate from variation at a single locus (polymorphic locus 1). In the 5-HTTLPR of rhesus monkeys (rh5-HTTLPR) we found an alternative locus for length variation (polymorphic locus 2) generated by a 21 bp insertion/deletion event. The existence of a distinct biallelic variation of the 5-HTTLPR in rhesus monkeys but similar allele and genotype frequencies in this species and humans supports the notion that there may be a relationship between functional 5-HT transporter expression, anxiety-related traits, and the complexity of socialization in human and non-human primate populations.

Carboxyl-truncated STAT5beta is generated by a nucleus-associated serine protease in early hematopoietic progenitors

Hematopoiesis is tightly controlled by a family of cytokines that signal through a related set of receptors. The pleiotropic and overlapping response of a cell to different cytokines is reflected in the number and complex pattern of activated signal transducers. Of special interest is STAT5, which is stimulated by a large and diverse set of cytokines. In addition to the two highly homologous proteins, STAT5A and STAT5B, encoded by duplicated genes, expression and activation of a dominant-negative, carboxyl-truncated form has also been described in early hematopoietic progenitors. We show here that a protease expressed in early hematopoietic cells cleaves the alpha forms of STAT5A/5B (p96/p94) to generate carboxyl-truncated beta forms (p80/p77). Inhibition studies assigned this protease to the serine class of endopeptidases. Cell fractionation experiments showed that the protease is associated with the nucleus in a constitutively activated form and does not require an activated STAT5 substrate. The ability of a protease to modulate the specificity of an activated transcription factor is unprecedented and underlines the importance of proteases in regulation of cell functions.

Arterio-venous carboxyhemoglobin difference suggests carbon monoxide production by human lungs

Carbon monoxide is hypothesized to be produced by the enzyme heme oxygenase predominantly in liver and spleen, bound to hemoglobin, and excreted by the lungs. Thus, venous carboxyhemoglobin is expected to be higher or equal to arterial carboxyhemoglobin. Unspecific inflammatory stimuli have been shown to induce heme oxygenase in lung tissue possibly leading to pulmonary carbon monoxide production. Arterial and central venous carboxyhemoglobin levels were measured in critically ill patients on the third day of ICU stay (n = 59) as well as in otherwise healthy humans prior to orthopedic surgery (n = 29). Arterial and central venous carboxyhemoglobin were higher in ICU patients than in healthy humans, respectively. In both groups, arterial carboxyhemoglobin was significantly higher than central venous carboxyhemoglobin. The arteriovenous carboxyhemoglobin differences were similar in both groups. The data suggest (a) increased CO-generation in critical illness and (b) pulmonary CO-production in healthy and critically ill humans.

Introduction

First-generation diode lasers produced stimulated emission from thick active regions consisting of a single semiconductor material. However, not long after epitaxial growth techniques advanced to the point of allowing thin heterostructure layers to be deposited with a high degree of control and precision, the quantum well laser was born. It soon became apparent that besides providing a valuable vehicle for studying fundamental quantum physics and optics in a solid state environment, quantum well diode lasers were also capable of dramatic performance improvements over their bulk counterparts. The lowering of threshold current densities was especially impressive.

High-temperature HgTe/CdTe multiple-quantum-well lasers

While most previous studies of Hg-based mid-IR lasers have focused on either bulk Hg(1-x)Cd(x)Te alloys or thick (> 100 A) Hg(1-x)Cd(x)Te quantum wells with relatively large x, we show that much thinner (20-30 A) HgTe binary wells may be engineered to suppress both Auger recombination and intervalence free carrier absorption. On the basis of detailed numerical simulations, we predict 4.3 m cw emission at temperatures up to 220 K for optical pumping and 105 K for diode operation. In pulsed mode, we expect maximum lasing temperatures more than 100 K higher than any prior Hg-based mid-IR result.