High-throughput SNP genotyping with the Masscode system

QIAGEN Genomics, Inc, has developed the Masscode tagging system for DNA labeling and detection. In this application, the Masscode system is described as applied to high-throughput single-nucleotide polymorphism (SNP) genotyping. The labeling system is based on a small-molecular-weight tag that is covalently attached through a photocleavable linker to a DNA oligonucleotide. The tagged oligonucleotide is used as a primer in an allele-specific PCR SNP discrimination assay. The allele-specific amplicons are differentiated through their Masscode tag assignments. After a photolysis step to cleave the tags from the amplicon, the samples are introduced into a single quadrupole mass spectrometry detection system for analysis. Genotyping determinations are based on the relative proportions of the paired allele tags. The system has a lower limit of detection in the femtomolar range (10(-15) M). At present, 30 different Masscode tags may be used simultaneously in a multiplex fashion to routinely provide more than 40,000 SNP genotyping measurements daily. Further developments will allow for the simultaneous detection of several hundred tags.

Pharmacokinetics of the 5HT3 receptor antagonist tropisetron in children

A pharmacokinetic study in children was performed to assess whether the pharmacokinetic profile of tropisetron in pediatric patients in similar to that in adults. In three pediatric centers, three dosages were tested in two age groups during chemotherapy (Group A, 3-6 years, 2, 5, or 20 mg/m2; group B, 7-15 years, 2, 5, or 20 mg). Children received tropisetron intravenously (course 1) or orally (course 2) before the start of chemotherapy. Blood samples were drawn over 24 hours. Tropisetron treatment continued for up to 6 days at the same daily dose, administered orally. Data were available for 45 patients after intravenous and for 38 patients after oral administration. 82% of course 1 patients and 72% of course 2 patients had no emesis on day 1. Headache occurred in eight patients and abdominal symptoms in three patients. Terminal half-life (5.3-6.6 hours), tmax (1.4-1.5 hours), and absolute bioavailability (41-42%) were identical in both age groups and comparable to those in adults. Because of a smaller volume of distribution, group A children showed a higher Cmax/dose (P < .001) and a higher area under curve (AUC) dose (P < .05) than adults. All parameters were independent of the dose administered. In conclusion, the elimination and absolute bioavailability of tropisetron in children are similar to those in adults. Because of its age-dependent volume of distribution, tropisetron should be administered once a day according to the body surface area in children below 10 years of age.

Sandostatin LAR (microencapsulated octreotide acetate) in acromegaly: pharmacokinetic and pharmacodynamic relationships

Double-blind, single-dose studies of 120 acromegalic patients given 10, 20, and 30 mg Sandostatin LAR (Sandoz Pharma Ltd, Basel, Switzerland) established the drug's pharmacokinetic profile. Patients then entered open-labeled extension phases, with Sandostatin LAR intramuscular (IM) injections every 4 weeks. These produced broadly constant octreotide concentrations with dose proportionality. Area fluctuations were minimal. Steady-state conditions were generally reached after the second to third injection. There was no evidence of downregulation with Sandostatin LAR over 1 year of study. Based on the pharmacokinetic/pharmacodynamic relationship of octreotide, a starting dose of 20 mg Sandostatin LAR and administrations every 4 weeks provide growth hormone (GH) control comparable to the thrice-daily subcutaneous (SC) injection regimen, which is commonly 0.3 to 0.6 mg/d. The reduction from the burden of two to three SC injections per day is a particular advantage of Sandostatin LAR, which is an attractive alternative to the approved Sandostatin injection.

Sandostatin LAR: a promising therapeutic tool in the management of acromegalic patients

A stable and sustained suppression of growth hormone (GH) secretion was noted in 101 patients treated long term with individual doses (20 and 30 mg in 89 patients, 40 mg in 12 patients) of Sandostatin LAR (Sandoz Pharma Ltd, Basel, Switzerland). Doses of 20 mg and 30 mg at 4-week intervals delivered average octreotide concentrations of 1,348 +/- 483 ng/L and 2,631 +/- 1,026 ng/L, respectively, in steady-state conditions and provided adequate control of patients who had been well controlled during treatment with 0.1 mg and 0.2 mg thrice-daily subcutaneous (SC) Sandostatin. Suppression of GH serum concentrations to less than 5 micrograms, 2 micrograms, and even 1 microgram/L was recorded in more patients and more consistently during long-term treatment with Sandostatin LAR than Sandostatin. A marked decrease or even a normalization of insulin-like growth factor-1 (IGF-1) serum concentrations was observed after the first double-blind 10-, 20-, or 30-mg dose of Sandostatin LAR. A progressive improvement was recorded during long-term treatment, with normalization of IGF-1 serum concentrations in 65.3% of patients. A marked clinical improvement was observed in parallel, with 36 of 101 patients (35.6%) becoming asymptomatic after the nineteenth injection of Sandostatin LAR. A greater than 20% shrinkage of the GH-secreting adenoma was also recorded in 12 of 14 patients treated with Sandostatin LAR after receiving only 2 to 4 weeks of treatment with SC Sandostatin and in 11 of 18 patients receiving Sandostatin LAR as adjuvant therapy after failure of surgery. The systemic tolerability of Sandostatin LAR was good, and most adverse events were mild and short term (1 to 2 days). No impairment of thyroid function was detected. Newly occurring gallstones were recorded in four of 101 patients and microlithiasis in four of 101 after up to 30 months of treatment with Sandostatin LAR. Due to its excellent efficacy, good tolerability, convenience of administration, and acceptability by patients, Sandostatin LAR is considered a promising therapeutic tool in the management of acromegalic patients.

Spontaneous conscious covert cognition states and brain electric spectral states in canonical correlations

Correlations between subjective, conscious, spontaneous cognitions and EEG power spectral profiles were investigated in 20 normal volunteers (2 sessions each) during relaxation-drowsiness-sleep onset. Four-channel EEG (temporal-parietal and parietal-central, left and right) was continuously recorded. The subjects were prompted 15 times per session to give brief reports of their ongoing thoughts. The reports were rated on 23 scales, and the 16 seconds of EEG recording preceding the prompts were spectral analyzed. Canonical correlation analysis was applied to the data (23 cognition ratings and 124 EEG spectral values for each of the 538 prompts). Four of the 23 pairs of canonical EEG variables and cognition variables were significant (p < 0.016) with correlation coefficients ranging from 0.78 to 0.62. The four pairs of canonical variables showed distinctive features in EEG spectra and cognition styles. The results demonstrate ruleful correspondences between EEG states and spontaneous, conscious, covert, cognitive-emotional states in a no-input, no-task, no-response paradigm.

A comparison of octreotide, bromocriptine, or a combination of both drugs in acromegaly

We investigated the pharmacokinetics of bromocriptine and octreotide, both individually and in combination, in 12 patients with active acromegaly. The pharmacodynamics of the drugs were assessed by 12-h profiles of GH secretion and insulin-like growth factor-I (IGF-I) measurements. During the 42-day study period, bromocriptine was administered for 28 days (from day 8; 5 mg, orally, twice daily) and octreotide (200 micrograms, sc, twice daily) from days 15-42. IGF-I levels, 12-h GH, and plasma bromocriptine and octreotide profiles were obtained on days 0, 14, 28, and 42. During bromocriptine treatment, both the area under the GH day curves (AUC) and mean IGF-I decreased to 64% (95% confidence limits, 43-72% and 48-82%, respectively) of initial values. During octreotide treatment, the respective values were 23% (18-30%) and 32% (21-36%), which were greater decreases than those during bromocriptine treatment [36% (95% confidence limits, 32-54%) for AUC for GH and 50% (95% confidence limits, 34-58%) for IGF-I]. With combined treatment, the AUC for GH was reduced to 16% (12-21%) and that of IGF-I to 25% (16-27%) of initial values. This combination was more effective than bromocriptine [25% (95% confidence limits, 22-37%) for AUC for GH and 39% (95% confidence limits, 25-43%) for IGF-I] and octreotide alone [78% (95% confidence limits, 53-89%) for AUC for GH and 78% (95% confidence limits, 57-98%) for IGF-I]. The pharmacokinetic parameters of octreotide were unchanged by the coadministration of bromocriptine. The bioavailability of bromocriptine increased by approximately 40% when bromocriptine was administered together with octreotide compared with administration alone (P < 0.01). Bromocriptine disposition parameters were unaltered. In conclusion, treatment of acromegalics with a combination of octreotide and bromocriptine increases the bioavailability of bromocriptine and reduces both GH and IGF-I levels more effectively than treatment with either drug alone. This presents the possibility of less frequent drug administrations, lower doses of octreotide, and, consequently, lower treatment costs.

Pharmacokinetics and haemodynamic effects of a single oral dose of the novel ACE inhibitor spirapril in patients with chronic liver disease

The pharmacokinetics and haemodynamic effects of orally administered spirapril, a novel angiotensin-converting enzyme (ACE) inhibitor, have been investigated in patients with liver cirrhosis (n = 10), in patients with chronic, non-cirrhotic liver disease (n = 8) and in a control group of healthy subjects (n = 16). The absorption and elimination of spirapril did not differ between patients with liver disease and control subjects. In contrast, the bioavailability of spiraprilat, the metabolite responsible for the pharmacological action of spirapril, was significantly reduced in patients (AUC 820 micrograms.h.l-1, 923 micrograms.h.l-1 and 1300 micrograms.h.l-1 in patients with cirrhosis, patients with non-cirrhotic liver disease and in healthy subjects, respectively. Compared to healthy subjects, cirrhotic patients had a reduced rate constant of spiraprilat formation (1.10 h-1 in patients vs. 2.00 h-1 in control subjects) while the elimination half-life of spiraprilat was not different. The effect of spirapril on diastolic blood pressure was decreased in patients with chronic liver disease as compared to the controls. Thus, the pharmacokinetics of spirapril was unchanged in patients with different types of liver disease, including cirrhosis. However, the bioavailability of spiraprilat and hypotensive effect of spirapril were reduced in patients.

Effects of diclofenac on isradipine pharmacokinetics and platelet aggregation in volunteers

In this open, two-period crossover study in 18 healthy male volunteers, a single oral dose of 50 mg diclofenac was administered alone and on day 7 of multiple oral dosing of 5 mg b.i.d. isradipine to assess a possible pharmacokinetic interaction. The effect of these drugs on ex vivo platelet function was also determined. Serial blood samples were obtained over 12-hour periods on three occasions: after the single diclofenac dose; after the morning dose of isradipine on day 6 and after co-administration of both drugs on day 7 of steady-state isradipine administration. Additional samples were taken at 2 h post dose for determination of ex vivo platelet aggregation. Isradipine plasma concentrations were determined by a gas chromatographic method and diclofenac plasma concentrations by an HPLC method. The pharmacokinetic characteristics of diclofenac were unaltered during co-administration. The maximum plasma concentration of isradipine was increased 19.6% during co-administration from 5.06 to 6.05 ng.ml-1. This is not expected to be of clinical importance. Isradipine's apparent total body clearance and steady-state AUC remained unchanged. Ex vivo induced platelet aggregation was not affected by any of the treatments.

Dose-proportional pharmacokinetics of terbinafine and its N-demethylated metabolite in healthy volunteers

The dose-dependency of the pharmacokinetic parameters of terbinafine and its N-demethyl derivative was investigated in a randomized four-way crossover study in healthy volunteers following single oral administrations of 125, 250, 500 and 750 mg of terbinafine. Plasma concentrations of terbinafine and its metabolite were measured by a validated high-performance liquid chromatography (HPLC) method using ultraviolet detection. Concentration data were fitted to a two-compartment model. The relationship between Cmax or the area under the concentration curve (AUC) and the terbinafine dose was analysed by classical linear regression. Terbinafine disposition parameters were dose-independent, with the exception of Tmax and t1/2 alpha, which were prolonged with the 500- and 750-mg doses. The terbinafine Cmax and AUC, however, were linear and dose-proportional over the entire dose range. The N-demethylated metabolite appeared in plasma at the same time as terbinafine and showed similar prolongations in Tmax and t1/2 alpha with the 500- and 750-mg doses. In addition, the Cmax deviated from proportionality at these doses, giving values 22% lower than projected, while the AUC was linear and dose-proportional over the whole range of doses. The slight disproportionality in the dispositions of terbinafine and its N-demethyl metabolite at 500 and 750 mg are not expected to be clinically significant.

Human monoclonal antibodies neutralizing cytomegalovirus (CMV) for prophylaxis of CMV disease: report of a phase I trial in bone marrow transplant recipients

The safety and pharmacokinetics of the two neutralizing human IgG1 monoclonal antibodies to cytomegalovirus (CMV) SDZ 89-104 and 89-109 in bone marrow transplant (BMT) recipients was assessed in an open phase I trial. Thirteen patients, 8 seropositive and 5 seronegative for CMV, were treated with allogeneic or autologous bone marrow transplantation. SDZ 89-104 was given to 5 and SDZ 89-109 to 8 patients. Patients were divided into high- and low-dose groups. A fixed prestudy dose of 0.1 mg/kg was given 4 days before BMT. On days 3, 17, 31, 45, 59, and 73, patients were treated with either 0.5 or 2 mg/kg of the respective antibody. Results indicate that doses of 2 mg/kg of SDZ 89-104 or SDZ 89-109 in alternating weeks can be safely administered to BMT patients. Serum trough levels measured by antiidiotype ELISA were approximately 10 micrograms/ml after administration of 0.5 mg/kg and approximately 50 micrograms/ml after treatment with 2 mg/kg of SDZ 89-104 or SDZ 89-109. High serum levels defined by antiidiotype ELISA techniques closely paralleled increased neutralizing activity. Serum half-lives calculated from these data were approximately 6 days.

Daytime noise stress and subsequent night sleep: interference with sleep patterns, endocrine and neurocrine functions

The effects of strong daytime noise stress on subsequent undisturbed night sleep were studied in six male volunteers. They slept for seven consecutive nights in the laboratory, two nights being preceded by an 8 h exposure to 83 dB (A) pink noise. Continuously during all nights EEG, EOG, EMG, ECG and respiration were recorded. Additionally, during five nights, blood samples were taken every 30 min by an indwelling venous catheter for the determination of ACTH, hGH, PRL, TRP, 5-HT and 5-HIAA. After daytime noise load, increased sleep stage 4 stability, partly elevated hGH and PRL levels and decreased levels of the metabolites of the serotonergic system were found. This result may be explained by the assumption that high daytime noise stress is an additional load for the CNS which demands an intensification of recovery processes during the sleep of the subsequent night.

Daytime noise and subsequent night sleep in man

The effects of daytime noise on recovery processes during subsequent undisturbed night sleep were studied in six healthy men (21-27 years), exposed to 80 dB (A) pink noise 8 h per day for 2 days. Sleep EEG, ECG, and respiration were recorded in the laboratory for five consecutive nights: two baseline nights, two nights following noise stimulation, and again one baseline night. Additionally questionnaire data were collected, reflecting a subjective impairment of the recovery function of sleep after noise exposure. EEG sleep data of the first post-noise night showed an increase in slow wave sleep with a simultaneous decrease in stage 2 sleep. During the second post-noise night these changes were less prominent. Three subjects additionally showed an instability in the sleep course coinciding with elevated heart and respiration rates. However, altogether the autonomic parameters were not clearly affected by the noise exposure. The findings support the assumption that strong daytime noise may interfere with subsequent sleep processes.