Relationship between Cnm-positive Streptococcus mutans and cerebral microbleeds in humans.

OBJECTIVE: Cerebral hemorrhage has been shown to occur in animals experimentally infected with Streptococcus mutans carrying the collagen-binding Cnm gene. However, the relationship between cerebral microbleeds and oral hygiene, with a focus on Cnm gene-positive S. mutans infection, remains unclear. MATERIAL AND METHODS: One hundred and thirty-nine subjects participated. The presence or absence of Cnm-positive S. mutans and its collagen-binding activity were investigated using saliva samples, and relationship with cerebral microbleeds detected on MRI investigated, including clinical information and oral parameters. RESULTS: Fifty-one subjects were identified as Cnm-positive S. mutans carriers (36.7%), with cerebral microbleeds being detected in 43 (30.9%). A significantly larger number of subjects carried Cnm-positive S. mutans in the cerebral microbleeds (+) group. S. mutans with Cnm collagen-binding ability was detected in 39 (28.1%) of all subjects, and the adjusted odds ratio for cerebral microbleeds in the Cnm-positive group was 14.4. Regarding the presence of cerebral microbleeds, no significant differences were noted in the number of remaining teeth, dental caries, or in classic arteriosclerosis risk factors. CONCLUSIONS: The occurrence of cerebral microbleeds was higher in subjects carrying Cnm-positive S. mutans, indicating that the presence of Cnm-positive S. mutans increases cerebral microbleeds, and is an independent risk for the development of cerebrovascular disorders.

Fgf10 is essential for limb and lung formation.

The interactions between fibroblast growth factors (FGF) and their receptors have important roles in mediating mesenchymal-epithelial cell interactions during embryogenesis. In particular, Fgf10 is predicted to function as a regulator of brain, lung and limb development on the basis of its spatiotemporal expression pattern in the developing embryo. To define the role of Fgf10, we generated Fgf10-deficient mice. Fgf10-/- mice died at birth due to the lack of lung development. Trachea was formed, but subsequent pulmonary branching morphogenesis was disrupted. In addition, mutant mice had complete truncation of the fore- and hindlimbs. In Fgf10-/- embryos, limb bud formation was initiated but outgrowth of the limb buds did not occur; however, formation of the clavicles was not affected. Analysis of the expression of marker genes in the mutant limb buds indicated that the apical ectodermal ridge (AER) and the zone of polarizing activity (ZPA) did not form. Thus, we show here that Fgf10 serves as an essential regulator of lung and limb formation.

A genome-wide association study of coping behaviors suggests FBXO45 is associated with emotional expression.

Individuals use coping behaviors to deal with unpleasant daily events. Such behaviors can moderate or mediate the pathway between psychosocial stress and health-related outcomes. However, few studies have examined the associations between coping behaviors and genetic variants. We conducted a genome-wide association study (GWAS) on coping behaviors in 14088 participants aged 35 to 69 years as part of the Japan Multi-Institutional Collaborative Cohort Study. Five coping behaviors (emotional expression, emotional support seeking, positive reappraisal, problem solving and disengagement) were measured and analyzed. A GWAS analysis was performed using a mixed linear model adjusted for study area, age and sex. Variants with suggestive significance in the discovery phase (N = 6403) were further examined in the replication phase (N = 7685). We then combined variant-level association evidence into gene-level evidence using a gene-based analysis. The results showed a significant genetic contribution to emotional expression and disengagement, with an estimation that the 19.5% and 6.6% variance in the liability-scale was explained by common variants. In the discovery phase, 12 variants met suggestive significance (P < 1 × 10-6 ) for association with the coping behaviors and perceived stress. However, none of these associations were confirmed in the replication stage. In gene-based analysis, FBXO45, a gene with regulatory roles in synapse maturation, was significantly associated with emotional expression after multiple corrections (P < 3.1 × 10-6 ). In conclusion, our results showed the existence of up to 20% genetic contribution to coping behaviors. Moreover, our gene-based analysis using GWAS data suggests that genetic variations in FBXO45 are associated with emotional expression.

Urinary iron excretion depends on the mode of administration of the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one in patients with homozygous beta-thalassemia.

OBJECTIVE: To examine the effect of frequency of oral administration of 1,2-dimethyl-3-hydroxypyrid-4-one (L1) on urinary iron excretion. HYPOTHESIS: Sustained serum concentrations of L1 will cause more iron chelation than the same daily dose given in larger but less frequent amounts. PATIENTS AND METHODS: Ten patients with thalassemia with a mean age of 20.9 +/- 4.7 years (range, 13 to 27 years), who were receiving regular treatment with 75 to 100 mg/kg/day oral L1, received 75 mg/kg/day L1 orally in equally divided doses: every 6 hours for 3 days and every 12 hours for 3 days. The two study periods occurred 1 month apart immediately after the monthly blood transfusions. Urine was collected for two consecutive 24-hour periods during each of the different schedules. Serial blood samples were collected from six patients over a 6-hour period and analyzed for total L1 and the L1 glucuronide metabolite concentrations. RESULTS: The patient's mean hemoglobin levels (138.8 +/- 12.5 and 139.0 +/- 11.6 gm/L) and ferritin levels (2856.4 +/- 2207.8 and 2890.0 +/- 2264.4 micrograms/L) were similar during the every-6-hour and every-12-hour L1 administrations, respectively. There was significantly more urinary iron excretion when L1 was administered every 6 hours (0.59 +/- 0.29 mg/kg/day) versus every 12 hours (0.40 +/- 0.26 mg/kg/day; p = 0.0129). Calculated 24-hour area under the plasma concentration-time curve of L1 was similar during the every-6-hour (7023.9 +/- 2637.8 mg.min/L) and every-12-hour (7050.1 +/- 1668.8 mg.min/L) experiments. CONCLUSIONS: These data suggest that the sustained presence of L1 in the blood results in greater chelation of iron than that observed with larger, less frequent doses.

Relationship between the pharmacokinetics and iron excretion pharmacodynamics of the new oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one in patients with thalassemia.

Single-dose and steady-state pharmacokinetics of the new oral iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one (L1) were studied in 14 patients with thalassemia and correlated with iron excretion. Food prolongs the rate of absorption of L1, but it does not affect significantly the extent of absorption measured by the area under the plasma concentration-time curve. Similarly, it does not affect the chelation potential of the drug. The mean elimination half-life of the drug is 3 hours, suggesting that a divided dose every 8 hours may assure better chelation. Our steady-state studies reveal that urinary iron excretion is independently influenced by body iron load (measured by ferritin levels) and by steady-state trough concentrations of the drug. While patients were receiving an unchanged regimen of 75 mg/kg/day, we have detected a gradual and significant decrease in trough concentrations in the presence of unchanged patients' compliance monitored by the Medication Event Monitoring System, diaries, and pill count. These findings suggest self-induction of L1 metabolism or decreased absorption during long-term therapy. Because of the concentration-dependent iron excretion, patients may need increasing doses to achieve negative iron balance.

Pregnancy outcome following gestational exposure to venlafaxine: a multicenter prospective controlled study.

OBJECTIVE: Because there are no studies available on the safety of venlafaxine during pregnancy, the authors' goal in this study was to determine whether venlafaxine increases the risk for major malformations. METHOD: Data on 150 women exposed to venlafaxine during pregnancy in seven pregnancy counseling centers were compared with data from studies of pregnant women who 1) received selective serotonin reuptake inhibitor antidepressants (SSRIs) (N=150) and 2) who received nonteratogenic drugs (N=150). RESULTS: Among the 150 women who were exposed to venlafaxine during pregnancy, 125 had live births, 18 had spontaneous abortions, and seven had therapeutic abortions; two of the babies had major malformations. There were no significant differences between these women and the two comparison groups on any of the measures analyzed. CONCLUSIONS: These results suggest that the use of venlafaxine during pregnancy does not increase the rates of major malformations above the baseline rate of 1%-3%.

Pregnancy outcome following first trimester exposure to sumatriptan.

We prospectively compared pregnancy outcome after exposure to sumatriptan with that of disease-matched controls and nonteratogen controls. There were no differences in the rates of live births, spontaneous abortions, therapeutic abortions, or major birth defects among the three groups. This first prospective report suggests that the use of sumatriptan during organogenesis is not associated with an apparent increased risk of major birth defects.

Oral iron chelation with 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in iron loaded thalassemia patients.

Despite the successes of deferoxamine (DFO) in the treatment and prevention of iron overload, an effective orally available iron chelating drug is needed, since erratic compliance with irritating, cumbersome parenteral infusions still results in fatal iron accumulation in many patients. Disorders of increased iron absorption should also benefit from the development of safe and effective iron chelating agents. Individuals with non-transfusion-dependent thalassemia (thalassemia "intermedia"), exhibit excessive dietary iron absorption that can lead to serious iron loading by the second or third decade of life. An orally effective iron-chelating drug would have major therapeutic advantages for all these patients.

Assessment of the palatability of beta-lactamase-resistant antibiotics in children.

OBJECTIVES: To evaluate the palatability of antibiotics effective against beta-lactamase-producing bacteria in children and to compare the results obtained with those obtained in adults. DESIGN: A taste test of 4 antibiotic suspensions: a combination of amoxicillin and clavulanic acid (banana), azithromycin (cherry), clarithromycin (wild fruit), and a combination of erythromycin and sulfisoxazole (strawberry-banana). SETTING: Outpatient setting. SUBJECTS: A volunteer sample of 50 healthy children (mean +/- SD age, 6.3 +/- 1.3 years) and 20 adults. MAIN OUTCOME MEASURES: After each antibiotic test dose, subjects rated its taste on a 10-cm visual analog scale incorporating a facial hedonic scale. RESULTS: The mean +/- SD taste scores of the antibiotics as rated by the children were as follows: amoxicillin-clavulanic acid, 5.7 +/- 3.6 cm; azithromycin, 6.8 +/- 3.2 cm; clarithromycin, 3.7 +/- 3.6 cm; and erythromycin-sulfisoxazole, 4.9 +/- 3.5 cm. The mean +/- SD taste score for erythromycin-sulfisoxazole (ie, 2.7 +/- 2.3) assigned by the adults was significantly different than that given by the children (P = .01) with no difference noted for the other 3 drugs. Children and adults both selected azithromycin most often as best tasting. There was a significant difference in the proportions selecting each antibiotic as worst tasting, with the children tending to dislike clarithromycin and the adults tending to dislike erythromycin-sulfisoxazole (P = .03). CONCLUSIONS: The taste of azithromycin was rated most highly by both children and adults, who also selected this antibiotic most often as best tasting. Differences in taste-testing results between children and adults suggest that evaluation of the palatability of medications intended for use in pediatrics should be conducted in children.

Compliance with prescription filling in the pediatric emergency department.

OBJECTIVES: To determine the rate of compliance with filling of prescriptions written in a pediatric emergency department and to examine the reasons for not filling the prescriptions. DESIGN: Compliance with filling prescriptions was determined using a follow-up standardized telephone questionnaire, designed so that it was not obvious that assessing prescription filling was the major reason for the study. Compliance herein was defined as having the prescription filled on the same or next day of the pediatric emergency department visit. SETTING: Pediatric emergency department of a tertiary care hospital. SUBJECTS: Pediatric patients discharged home with a drug prescription. MAIN OUTCOME MEASURE: The proportion of prescriptions written in the pediatric emergency department that were filled on either the same or next day as determined by telephone follow-up. This outcome is expressed as a proportion with 95% confidence interval. RESULTS: Follow-up was completed in 1014 (83%) of the 1222 children, aged 4.5 +/- 4.2 (mean +/- SD) years. Compliance with prescription filling was 92.7% (940/1014). Parental reasons for not filling the prescription included medication unnecessary (27%), financial (6.8%), and not enough time (6.8%). Dissatisfaction with the explanation of the medical problem, instructions for treatment, and instructions for follow-up treatment were significantly associated with noncompliance by univariable logistic regression (P<.05). CONCLUSION: The rate of prescription nonfilling in children seen in a pediatric emergency department is at least 7%, although lower than that in adults in a similar setting.

Palatability of oral antibiotics among children in an urban primary care center.

OBJECTIVE: To evaluate the palatability of antimicrobial agents effective against beta-lactamase-producing bacteria in American children. DESIGN: In a taste test of 4 antimicrobial agents, azithromycin (cherry flavored), cefprozil (bubble gum flavored), cefixime (strawberry flavored), and amoxicillin-clavulanic acid (banana flavored) were compared. SETTING: An urban inner-city primary care clinic. SUBJECTS: A volunteer sample of 30 healthy children (aged 5-8 years). INTERVENTION: Palatability was determined using a single-blind taste test of 4 flavored antimicrobial agents. The 4 antimicrobial agents used were azithromycin, cefprozil, cefixime, and amoxicillin-clavulanic acid. MAIN OUTCOME MEASURES: After each antimicrobial test dose, subjects rated the taste on a 10-cm visual analog scale incorporating a facial hedonic scale. Preference assessments for the best-tasting and worst-tasting agent were also conducted. RESULTS: Of the 20 children who expressed a preference, significantly more children (9 [45%], P<.05) selected the cefixime preparation as the best-tasting formulation compared with the other preparations. The cefixime preparation was also significantly the least likely to be selected as the worst-tasting preparation (2 [10%], P<.05). There were no significant differences between the other 3 preparations with respect to being selected as either the best or worst tasting. The mean (+/- SD) visual analog scale score for cefixime was highest (8.53 [2.49]) compared with the scores for azithromycin (6.78 [3.45]), cefprozil (6.26 [4.04]), and amoxicillin-clavulanic acid (6.24 [4.01]). CONCLUSION: The cefixime preparation was most commonly rated as best tasting by children.

Critical comparison of novel and existing methods of compliance assessment during a clinical trial of an oral iron chelator.

The assessment of compliance is critical in the evaluation of the effectiveness of a new therapeutic agent. Fifteen patients with transfusion-dependent beta-thalassemia, many of whom had previously demonstrated erratic compliance with deferoxamine, were enrolled in a clinical trial of a new oral iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one (L1). Their compliance with this medication was estimated by several existing methods and the novel Medication Event Monitoring System (MEMS). Overall compliance as assessed by the MEMS was 78.5 +/- 13.0% of prescribed doses taken, significantly lower than the corresponding rates calculated by pill counts and diaries (91.5 +/- 9.2% and 94.1 +/- 4.3%, respectively). However, several serious problems were encountered with the MEMS, mostly in the form of incorrect use of the device by the patients. Disclosure of the nature of the MEMS and the compliance monitoring process did not alter the rate of adherence with L1 therapy. Compliance as determined by pill counts did not differ between the 1st and 2nd 6-month periods. Although not reaching statistical significance, a trend towards better L1 compliance occurred in those patients in whom serum ferritin levels decreased. Patients who filled at least 50% of their diaries had significantly better compliance by pill counts than those who completed less than 50% of their diaries (95.9 +/- 4.1% and 86.5 +/- 11.1%, respectively). Steady-state L1 trough concentrations and 24-hour urinary iron excretion did not correlate with L1 compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a eutectic mixture of local anesthetics for prolonged subcutaneous drug administration.

The efficacy of a eutectic mixture of local anesthetics (EMLA) in alleviating the pain associated with subcutaneous needle insertion for infusion of the iron-chelating agent, deferoxamine, was examined in 12 patients with homozygous beta-thalassemia. As reported by the patient using a 100-mm visual analogue scale, the pain of insertion was rated as significantly less after application of EMLA (mean +/- SD, 1.5 +/- 2.2 mm) than the pain associated with needle insertion without EMLA (34.8 +/- 33.5 mm, P = .005). Subsequently, in a double-blind randomized trial of 10 beta-thalassemia patients, EMLA was significantly better (5.7 +/- 8.2 mm) than placebo (27.0 +/- 22.8 mm, P = .01) in reducing the pain of needle insertion for deferoxamine infusion. No adverse effects were reported with the use of EMLA cream. These results suggest that EMLA may be effective in reducing the pain associated with needle insertion for subcutaneous deferoxamine infusion in beta-thalassemia patients, which may lead to improved compliance with this irritating, prolonged therapy. The safety of EMLA use in these patients, and others receiving regular parenteral therapy, should now be examined.

Multiple antibiotic sensitivity syndrome in children.

BACKGROUND: Multiple antibiotic sensitivity syndrome with adverse drug reactions to multiple classes of antibiotics has been described in adults but is not well characterized in children. PATIENTS AND METHODS: Charts of children referred to the adverse drug reaction clinic at the Children's Hospital of Western Ontario, London, Ontario, with adverse drug reactions to multiple antibiotics were reviewed to determine the number of patients with adverse drug reactions to multiple classes of antibiotics and the clinical characteristics of the adverse events. RESULTS: The records of 97 children who were selected as possible candidates for multiple antibiotic sensitivity were studied. These records constituted 11% of referrals to a highly specialized adverse drug reaction clinic, suggesting that in usual clinical practice, this entity, if it does indeed constitute a distinct clinical entity, is quite uncommon. Age at time of the first adverse drug reaction was 26.1+/-26.3 (mean +/- SD) months. Among the 97 children, adverse reactions to five classes of antibiotic were noted in 3.1%, to four in 10.3%, to three in 47. 4% and to two in 39.2%. Most children (85.6%) experienced an adverse reaction to a penicillin, while 71.1% reacted to a cephalosporin, 80. 4% to a sulphonamide and 35.1% to a macrolide. Clinical presentations of the adverse reactions included urticaria or pruritus, other rash, serum sickness-like reaction, angioedema or anaphylaxis, erythema multiforme or Stevens-Johnson syndrome. CONCLUSIONS: There are children who have what appears to be immunologically mediated adverse drug reactions to antibiotics of multiple classes. These reactions, which most commonly manifest as urticaria or other rashes, follow drug use patterns. It remains to be defined whether this is a distinct clinical syndrome or a manifestation of a more fundamental problem in dealing with xenobiotics in the setting of infection. Further work on the immunological and/or biochemical determinants of the multiple antibiotic sensitivity syndrome (MASS) is needed to understand the pathophysiology and determinants of MASS and whether MASS constitutes a distinct clinical entity.

Selection of treatment of cefaclor-associated urticarial, serum sickness-like reactions and erythema multiforme by emergency pediatricians: lack of a uniform standard of care.

BACKGROUND: Serum sickness-like reactions (SSLR) and erythema multiforme are common adverse effects of cefaclor therapy and can be associated with significant morbidity. No standardized evidence-based protocol for the optimal treatment of drug-induced SSLR exists. OBJECTIVES: To define the standard of care used by physicians treating adverse reactions associated with cefaclor. METHODS: A retrospective review of the medical records of children discharged from a pediatric emergency room with a diagnosis of adverse events to cefaclor was conducted. Charts of patients were reviewed to determine which therapy was prescribed. RESULTS: During the study period, 74 cases of adverse events attributed to cefaclor presented to the emergency department. SSLR were the most common pattern of adverse events seen (31 cases, 42%), followed by urticarial reactions (26 cases, 35%) and erythema multiforme (17 cases, 23%). An antihistamine was the treatment most often prescribed (88%) for erythema multiforme. Significantly more children with SSLR than with erythema multiforme or urticaria were treated with prednisone, either alone or in combination (P<0.05). CONCLUSIONS: The treatment most often prescribed for serious cefaclor-associated erythema multiforme was an antihistamine. In the case of SSLR, an antihistamine and prednisone were most commonly used. Prospective randomized, controlled trials are needed to define the role of various therapeutic agents and to determine the optimal therapy for SSLR and other serious adverse drug reactions.

Drug compliance in pediatrics. Clinical and research issues.

Noncompliance with therapy is widespread in children, with potentially important implications in clinical practice and the research setting. Compliance with therapy is a critical element in the success of therapy, that is, for an efficacious medication to be effective, it must be taken. Demonstration of patterns of drug adherence and the association between compliance and outcome in clinical practice have been facilitated by the recent introduction of electronic monitoring of medication compliance. Determinants of drug compliance, optimal measurement of compliance, and strategies to improve compliance remain to be further explored in children. Given the prevalence of and the potential consequence of noncompliance, pediatricians must have a high index of suspicion of noncompliance to provide the best possible care to their patients.

The pharmacokinetics and pharmacodynamics of the oral iron chelator deferiprone (L1) in relation to hemoglobin levels.

Recently, we demonstrated that administration of the orally active iron chelating agent deferiprone (1,2-dimethyl-3-hydroxypyrid-4-one (L1)) at 6-hour intervals results in significantly greater urinary iron excretion than that induced during administration of the drug at 12-hour intervals. That study was conducted in thalassemia patients, all of whom had received a packed red cell transfusion of 15 cc/kg. 72 hours prior to evaluation of urinary iron excretion, at a time when endogenous erythropoiesis would be expected to be at its lowest. In clinical practice however, thalassemia patients, suppression of endogenous erythropoiesis is not sustained between transfusions. We set out to determine the influence that administration of deferiprone has on urinary iron excretion at lower hemoglobin concentrations, immediately prior to transfusion. We hypothesized that hemoglobin levels will affect the ability of deferiprone to chelate iron. Ten regularly transfused patients with homozygous beta-thalassemia (HBT) aged mean +/- SD, 20.9 +/- 4.7, range 13 - 27 years, receiving long-term therapy with deferiprone, were treated with deferiprone 75 mg/kg/day, administered every 6 hours (or every 12 hours) for 72 hours immediately prior to a blood transfusion in the first month. One month later each patient received the other of the 2 dosing regimens for 72 hours immediately prior to transfusion. The deferiprone-induced 24-hour urinary iron excretion was similar during both dosing regimens; 0.56 +/- 0.45 mg/kg when L1 was given every 6 hours and 0.48 +/- 0.52 mg/kg when L1 was administered every 12 hours (p = 0.79). However, the calculated 24-hour area under the plasma concentration-time curve (AUC0-24) of deferiprone was significantly lower when deferiprone was administered at 6-hour intervals (6,762.8 +/- 1,601.6 mg*min/l), than that observed when deferiprone was administered every 12 hours (8,250.1 +/- 1,235.7 mg*min/l) (p = 0.04). The pharmacokinetics of deferiprone when administered immediately prior to transfusions are different from those following transfusions. More studies assessing total body iron excretion are needed to determine the contribution of the fecal route in iron excretion.

Prevention, diagnosis, and treatment of fetal toxoplasmosis.

Despite the limitations, the available data lead to the conclusion that treatment of the mother may be of benefit to the fetus. To date, harmful effects of maternal therapy on the fetus have not been substantiated. Current recommendations for fetal therapy of toxoplasmosis include the initiation of spiramycin in the pregnant woman when acquired toxoplasmosis is strongly suspected in pregnancy. Prompt detection of infection in the mother is important in order to start therapy as early as possible. An attempt to determine the status of the fetus is undertaken by prenatal diagnostic procedures such as amniocentesis, cordocentesis, and ultrasonography. After confirmation of fetal infection, repeated courses of a combination of pyrimethamine, sulfadiazine, and folinic acid should be alternated with courses of spiramycin. If the fetus is not infected, spiramycin should be continued in repeated courses or throughout pregnancy. Pregnancy termination tends to be reserved for cases in whom ultrasonographic examination demonstrates the fetus to be severely affected. The importance of postnatal follow-up and treatment, although not addressed in this article, must be emphasized. The advent of fetal therapy offers hope that the problem of congenital toxoplasmosis will become less common. In addition to currently available options, the future may offer new avenues of therapy, such as the possibility of treating infected fetuses by the intra-amniotic infusion of drugs.

Cytotoxic activity of a methanol extract of Phallusia nigra (Tunicata, Ascidiacea).

Tunicates have been reported to be a rich source of biologically active compounds. In this study, we demonstrate the presence of cytotoxic substances in Phallusia nigra, a common tunicate from Brazilian coastal waters. An extract of tunicate tissue was obtained by homogenizing the visceral organs from 50 specimens in methanol, followed by filtration and concentration in a rotary vacuum evaporator. Finally, the concentrate was partitioned with chloroform to remove lipids. The resulting extract possessed antimitotic and hemolytic activity. The former was demonstrated as a delay in the development of sea urchin eggs by partially inhibiting the process of cleavage (first cleavage, EC50 +/- SEM = 3.44 +/- 0.84 mg/ml). The < 500 molecular fraction of the extract obtained by ultrafiltration also inhibited cell proliferation (the number of viable cells was decreased by 68% with 500 micrograms/ml) and DNA synthesis of T47D cells derived from human breast carcinoma as measured by [3H]-thymidine incorporation (66% of the control value after 24-h incubation with 100 micrograms/ml). Dose-dependent hemolysis obtained with P. nigra extract on mouse erythrocytes had an EC50 +/- SEM = 1.12 +/- 0.02 mg/ml for a 0.5% erythrocyte suspension. Hemolysis could be reduced by pre-incubating the cells with choline-containing phospholipid. Sphingomyelin (40 micrograms/ml) increased the EC50 by two-fold to 2.86 +/- 0.04 mg/ml, but phosphatidylcholine (80 micrograms/ml) did not modify hemolysis.

Pharmacokinetics of arginine butyrate in patients with hemoglobinopathy.

Recent reports have demonstrated improvement in the clinical status and hemoglobin levels with use of intravenous arginine butyrate in patients with homozygous ß-thalassemia and sickle cell disease. To allow optimalization of therapy, we conducted pharmacokinetic studies in nine patients, five with sickle cell disease and four with ß-thalassemia, treated with continuous intravenous infusion of arginine butyrate. The disappearance of the drug after discontinuation was characterized by a biphasic elimination with an initial rapid phase followed by a slower phase. Redistribution was noted in five of the patients after 11.2 ± 4.0 min. The short half life was the result of both rapid clearance rate of 93.6 ± 31.9 ml/kg/min and small Vc (0.21 ± 0.26 l/kg) and Vss (0.31 ± 0.37 l/kg). While preliminary results of the effectiveness of arginine butyrate are encouraging with a rise of γ-globin mRNA and F reticulocytes in some patients, the rapid elimination of this agent will probably limit its current use to administration by continuous infusion.