Correlation of electron self-energy with geometric structure in low-energy electron diffraction.

In low-energy electron diffraction (LEED) studies of surface geometries where the energy dependence of the intensities is analyzed, the in-plane lattice parameter of the surface is usually set to a value determined by x-ray diffraction for the bulk crystal. In cases where it is not known, for instance in films that are incommensurate with the substrate, it is desirable to fit the in-plane lattice parameters in the same analysis as the perpendicular interlayer spacings. We show that this is not possible in a conventional LEED I(E) analysis because the inner potential, which is typically treated as an adjustable parameter, is correlated with the geometrical structure. Therefore, without having prior knowledge of the inner potential, it is not possible to determine the complete surface structure simply from LEED I(E) spectra, and the in-plane lattice parameter must be determined independently before the I(E) analysis is performed. This can be accomplished by establishing a more precise experimental geometry. Further, it is shown that the convention of omitting the energy dependency of the real part of the inner potential means geometrical LEED results cannot be trusted beyond a precision of approximately 0.01 Å.

Long-term stability of allozyme frequencies in a wood lemming, Myopus schisticolor, population with a biased sex ratio and density fluctuations.

Wood lemming (Myopus schisticolor) populations are characterized by female biased sex ratios and cyclic variations in population size. Both of these characteristics are assumed to reduce genetic variation and thus affect the evolutionary adaptation of the species. We addressed these questions by studying the genetic structure of a wood lemming population from eastern Finland by isozyme markers during a 21-year period, which corresponds to 40-50 generations. Contingency tests showed that genotypic proportions conformed to Hardy-Weinberg equilibrium in each of the four sampling years. Among the temporal replicates, allele frequencies differed most by 0.14 and were not significant. Genetic variation was also stable and fairly high with a mean observed heterozygosity of H = 0.057. Variability in the Heinavesi population was higher than previously reported in wood lemming. The difference was mainly caused by variation at a phosphoglucomutase locus that was monomorphic in earlier studies. Significant linkage disequilibrium was observed in three of the comparisons but the disequilibrium did not appear consistently in all years. This pattern was also evidenced by the variance components, which indicated that selection favoured for specific allele pairs only in few subsamples.

Meta-analysis of trials comparing toremifene with tamoxifen and factors predicting outcome of antiestrogen therapy in postmenopausal women with breast cancer.

Meta-analysis of all clinical data was conducted to compare toremifene 40-60 mg/day (TOR) with tamoxifen 20-40 mg/day (TAM) in postmenopausal women with estrogen receptor (ER) positive or ER unknown advanced breast cancer and assess factors predicting treatment outcome. Data from five randomized parallel group studies (all studies) were combined. Efficacy variables were the response rate in all studies and also the time to treatment failure and survival in the three major studies (pivotal studies). Of the 1421 patients, 725 received TOR and 696 TAM. Response rates were 24.0% and 25.3%, respectively (p = 0.675) with 95% confidence interval (95% CI) for the difference -5.3 to 3.4. Of the 1157 patients in the pivotal studies, 75% had progressed and 50% expired. Median treatment times were 4.9 months in TOR and 5.3 months in TAM groups (p = 0.762, hazard ratio 0.98 with 95% CI 0.87-1.11). Median survival times were 31.0 (TOR) and 33.1 (TAM) months (p = 0.758, hazard ratio 0.98 with 95% CI 0.83-1.15). All results are consistent with the criteria of statistical equivalence between TOR and TAM. More patients in TAM (20%) than in TOR (14%, p = 0.007) discontinued the treatment prematurely but overall the treatments were well tolerated. As the treatments were equally effective all data were analyzed together for predictive factors. High tumor ER concentration, long disease free time, soft tissue metastases, few metastatic sites, and good performance status all independently predicted longer survival (p<0.001). Previous adjuvant tamoxifen predicted shorter survival (p = 0.008). Objective response to treatment or disease stabilization for at least 12 months both predicted prolonged survival (p = 0.001). TOR 60 mg/day and TAM are equally effective and well tolerated in the treatment of advanced breast cancer in postmenopausal women. Probability of survival may be predicted based on patient characteristics and on the initial response to the treatment.

A practical approach for the assessment of bioequivalence under selected higher-order cross-over designs.

The two-period cross-over design with two sequences of drug administration is a standard experimental design when bioequivalence of one test formulation is to be assessed in comparison with a reference formulation. Previously, an approach based on Fieller's confidence interval has been presented for the assessment of average bioequivalence under this particular design. However, the two-sequence two-period cross-over design is not very useful in the presence of unequal carry-over effects. Besides, this basic design does not provide independent estimators for the intra-subject variabilities. To overcome these limitations, it might be of interest to consider a higher-order cross-over design in which the number of periods and/or the number of sequences is greater than the number of formulations to be compared. Because of this, the present communication will concentrate on the generalization of Fieller's confidence interval concept for a particular group of higher-order cross-over designs. In addition to this, since the evaluation of simple average bioequivalence does not guarantee that the two products can be used interchangeably, the assessment of population and individual bioequivalence is addressed through the application of a comprehensible three-step decision rule. An example study with a two-sequence four-period design is also analysed to illustrate the use of the proposed methods.

Inhibition of platelet monoamine oxidase type B by selegiline.

Selegiline is an irreversible inhibitor of monoamine oxidase type B (MAO-B). No comparative data are available on the MAO-B inhibition caused by orally and intravenously administered selegiline. This study aimed to clarify this matter and to investigate the dose-response of MAO inhibition caused by orally administered selegiline. Sixteen healthy volunteers were given selegiline as a single intravenous dose (0.5 mg) and in three low oral doses (0.5 mg, 1.0 mg, and 1.5 mg) in an open-label randomized crossover trial. The MAO-B inhibition after the 0.5-mg intravenous dose was 79.6 +/- 15.1%. The dose-response of the three oral doses causing MAO-B inhibition was logistic. To check whether this equation could be applied to higher doses, eight of the volunteers were given 5-mg and 10-mg oral doses. The MAO-B inhibition after these doses (84.9 +/- 11.9% and 95.6 +/- 4.5, respectively) fitted well with the logistic model. With this equation obtained, it was calculated that a 3.4-mg oral dose of selegiline would be needed to obtain the same degree of MAO-B inhibition as after the intravenous dose of 0.5 mg. Therefore, the ratio of MAO-B inhibitory potential of intravenously and orally given selegiline is approximately 7 to 1, which fits well with the low bioavailability of the drug after oral administration.

Desmethylselegiline, a metabolite of selegiline, is an irreversible inhibitor of monoamine oxidase type B in humans.

Selegiline, an irreversible and selective inhibitor of monoamine oxidase type B (MAO-B), is metabolized into desmethylselegiline, levomethamphetamine, and levoamphetamine. In animal experiments, desmethylselegiline also has been shown to be an irreversible inhibitor of MAO-B. This study investigated the inhibitory potential of MAO-B and the pharmacokinetics of desmethylselegiline in humans. A double-blind, crossover trial was performed to compare the effects of a single dose (10 mg) of selegiline or desmethylselegiline on MAO-B platelet activity. The urinary excretion of phenylethylamine, which is considered to be a parameter of MAO-B inhibition, also was measured. The concentrations of selegiline, desmethylselegiline, and their metabolites were measured in plasma after administration of the two compounds. Ten healthy volunteers participated in the study. There was a clear inhibition of platelet MAO-B by both compounds. Desmethylselegiline caused a 63.7 +/- 12.7% inhibition of platelet MAO-B compared with 96.4 +/- 3.9% caused by selegiline. The maximal inhibition by desmethylselegiline was reached significantly later after desmethylselegiline (time to reach maximal inhibition [tmax], 27 +/- 20 hours) than after selegiline administration (tmax, 1.4 +/- 1.4 hours). The platelet MAO-B activity returned to baseline levels within 2 weeks, thus reflecting the irreversible nature of the inhibition by both compounds. The cumulative 48-hour excretion of phenylethylamine was 33% lower after desmethylselegiline than after selegiline administration. All three major metabolites of selegiline could be detected in plasma after selegiline administration. Levoamphetamine was the only metabolite of desmethylselegiline. The area under the concentration-time curve from time 0 to 24 hours (AUC0-24) of desmethylselegiline was 33 times higher than that of selegiline, suggesting a better bioavailability of desmethylselegiline. Desmethylselegiline is an orally active, irreversible inhibitor of MAO-B and could possibly be used to treat Parkinson's disease in the same way as selegiline.

High-dose toremifene vs tamoxifen in postmenopausal advanced breast cancer.

To compare the efficacy and safety of high doses (200 or 240 mg/d) of toremifene (Fareston) to standard doses (20 or 40 mg/d) of tamoxifen (Nolvadex) in postmenopausal women with estrogen receptor (ER)-positive or ER-unknown advanced breast cancer, we pooled data from two randomized, three-arm clinical trials. Of the 733 patients included in the overview, 369 were randomized to high-dose toremifene and 364, to tamoxifen. At median follow-up of 19 months, disease had progressed in over 70% of the patients. Response rates were 25.2% in the high-dose toremifene arm and 19.8% in the tamoxifen arm (P = .087). The two treatments appeared to be statistically equivalent with respect to risk for disease progression and survival. Reversible SGOT elevation was observed in 26 tamoxifen-treated patients vs 64 high-dose toremifene recipients (P < .001) and nausea in 33 vs 50 patients (P = .085). Reversible corneal keratopathy was diagnosed in two patients on tamoxifen and eight on high-dose toremifene (P = .061). Treatment had to be discontinued in 17.3% of patients in the high-dose toremifene arm and 20.1% in the tamoxifen arm. Discontinuation due to toxicity was rare, and toxicity did not differ significantly between the treatments. Toremifene, in doses up to 240 mg/d, is an effective, safe treatment for postmenopausal women with ER-positive/unknown advanced breast cancer.

Comparison of toremifene and tamoxifen in post-menopausal patients with advanced breast cancer: a randomized double-blind, the 'nordic' phase III study.

The study was planned to compare, in a prospective double-blind randomized trial, the efficacy and safety of toremifene (TOR) and tamoxifen (TAM) in post-menopausal patients with advanced breast cancer who have not had prior systemic therapy for advanced disease. Four hundred and fifteen post-menopausal patients with oestrogen receptor (ER)-positive or ER-unknown advanced breast cancer were randomly assigned to receive daily either 60 mg TOR or 40 mg TAM. The patients were stratified to measurable and non-measurable but evaluable groups. They were assessed for response to therapy, time to progression (TTP), time to treatment failure (TTF), response duration, overall survival and drug toxicity. Two hundred and fourteen patients were randomized into TOR and 201 into TAM treatment. The response rate (complete + partial) was 31.3% for TOR and 37.3% for TAM (P = 0.215). The 95% confidence interval (CI) for the 6% difference was -15.1% to 3.1%. The median TTP was 7.3 months for TOR and 10.2 months for TAM (P = 0.047). The 95% CI for the hazard ratio of 0.80 was 0.64-1.00. A percentage of the TOR patients (9.8%) and the TAM patients (18.9%) discontinued the treatment prematurely (P = 0.011) for various reasons. Consequently, the median TTF of 6.3 vs 8.5 months did not differ significantly (P = 0.271). The hazard ratio was 0.89 and the subsequent 95% CI 0.73-1.09. The median overall survival was 33.0 months for TOR and 38.7 months for TAM (P = 0.645). The hazard ratio was 0.94 with 95% CI of 0.73-1.22. The transient difference in TTP may be related to an imbalance in ER content of the tumours. When only patients with ER-positive tumours were considered (n = 238), no difference between two treatments was seen (P = 0.578). TAM was associated with an overall slightly higher frequency of adverse drug reactions than TOR (44.3 vs 39.3%) and a higher discontinuation rate due to these events (3.5% vs 0.9%). Treatment-emerged moderate dizziness (P = 0.026) and cataracts (P = 0.026) were more frequent among TAM than among TOR patients. In conclusion, TOR (60 mg day(-1)) and TAM (40 mg day(-1)) are equally effective and safe in the treatment of advanced post-menopausal ER-positive or ER-unknown breast cancer.

A three-step procedure for assessing bioequivalence in the general mixed model framework.

Bioavailability data arising from a standard two-period cross-over study are routinely analysed to establish bioequivalence between test and reference formulations. Current regulatory guidelines only require evidence of equivalence in average bioavailability for the assessment of bioequivalence. Under normality assumptions, this is achieved by demonstrating equivalence between the formulation means (step 1). However, the equivalence of formulation variances should also be assessed to get evidence of population bioequivalence (step 2), since a difference in variability of bioavailability may also pose significant problems in drug safety and efficacy. On the other hand, even population bioequivalence does not ensure that an individual subject could be expected to respond similarly to the two formulations. Therefore, whenever individual bioequivalence is the ultimate goal, the magnitude of intra-subject correlation should always be examined as the final stage (step 3). In this paper, these three successive concepts of bioequivalence are cast into the general mixed model framework and a stepwise testing procedure for the global assessment of bioequivalence is proposed. In addition to this, important issues addressed in the regulatory guidelines, such as verification of the model assumptions and application of the log-transformation, are discussed. Lastly, an example is presented to illustrate the proposed three-step procedure on the original and log-transformed scale of measurement.

The effect of enoxaparin in prevention of deep venous thrombosis in hip and knee surgery--a comparison with the dihydroergotamine-heparin combination.

A randomized study was carried out in order to compare the low-molecular heparin enoxaparin to heparin-dihydroergotamine (HDHE) combination, as prophylactic anti-thrombotic measure in patients undergoing hip replacement or knee replacement surgery or fractures of the femoral neck. A total of 165 patients both female and male were included in the study. The patients were randomized into two treatment groups. One group was treated with heparin-dihydroergotamine 0.5 mg + 5,000 IU twice a day and the other with enoxaparin 40 mg once daily. All patients were examined with Doppler ultrasound on day 3-5 and after the termination of medication which was the end of the study. Positive Doppler ultrasound findings were confirmed either by duplex Doppler or phlebography and clinical signs of pulmonary embolism were confirmed by isotope scintigraphy. The overall incidence of thromboembolic events was low (3%). One deep venous thrombosis (DVT) was seen in the enoxaparin group and two cases of pulmonary embolism in the heparin-dihydroergotamine group. Thus, the two regimens showed comparable efficacy and the overall safety was comparable. However, enoxaparin caused significantly less injection site haematoma. Correspondingly, the size of the injection site haematoma was significantly smaller in the enoxaparin group.

Early selegiline therapy reduces levodopa dose requirement in Parkinson's disease.

In an earlier report of our placebo-controlled selegiline trial on de novo parkinsonian patients, we have shown that the need to start additional levodopa therapy is significantly postponed by using selegiline monotherapy. Now we report the two-year interim results of the double-blind continuation of the trial in 44 patients after the introduction of levodopa to the earlier therapy with placebo or selegiline (21 and 23 patients, respectively). The clinical disability was assessed by three rating scales. The daily dose of levodopa needed to maintain an optimal condition had to be increased progressively up to a 52% higher level in the placebo group than in the selegiline group (543 +/- 150 and 358 +/- 117 mg, respectively, p < 0.001). The number of daily doses of levodopa was also statistically significantly higher in the placebo group during the 24 months' observation period (p < 0.01). The ratio of levodopa doses that was expected to stay the same contrarily significantly increased suggesting that selegiline would, besides having the levodopa potentiating effect, also have a beneficial influence on the progression of the basic cerebral dopamine deficiency. The combination of selegiline and levodopa was well tolerated, and the adverse event profiles did not differ from each other. In conclusion, early selegiline therapy allows a significant saving in the subsequent levodopa dosage. This saving seems to become even stronger along with the treatment time.

Fieller's confidence intervals for the ratio of two means in the assessment of average bioequivalence from crossover data.

The two-period crossover design is the most commonly used study design for bioequivalence of one test formulation to be assessed in comparison to one reference formulation. Consequently, in this paper, all derivation is based on this particular design. It is assumed that for the underlying statistical model the usual assumptions of normality and additivity are satisfied on the original scale of measurement and that it is wanted to base the assessment of average bioavailability on the ratio of the unknown population means for the test and reference formulation. The purpose of this paper is to illustrate that it is reasonable to assume a uniform covariance structure for the two-period crossover design, because the demand of equal variability in bioavailabilities, in addition to equal average bioavailabilities, for the reference and test formulation makes the assumption of uniform covariance structure very realistic, and also because the properties of a decision rule based upon a Fieller's confidence interval under a uniform covariance structure are competitive with those of the corresponding rule based on a general covariance structure.

Does thermal stress decrease uterine blood flow in hypertensive pregnancies?

The aim of the study was to determine the acute effects of thermal stress on maternal and fetal circulatory responses in normal and hypertensive patients. Therefore we studied 14 healthy pregnant women and 12 women with compromised pregnancies during short-term heat stress using color Doppler ultrasound in addition to conventional follow-up methods. The uterine vascular resistance increased significantly during the exposure in the high-risk pregnancy group without change in the control group. The results of the present study give strong support to our earlier studies that short-term heat stress seems to be safe in uncomplicated pregnancies but may be detrimental in high-risk pregnancies.

High dose toremifene in advanced breast cancer resistant to or relapsed during tamoxifen treatment.

Fifty patients with advanced breast cancer refractory to prior tamoxifen therapy were assigned to investigational treatment with high-dose toremifene administered 120 mg orally twice a day. Treatment was generally well tolerated. The majority (80%) of the patients had no side effects, and among the remaining 10 patients reported side effects were mostly mild and/or transient. Two objective tumor responses were observed: one complete response (CR), duration 6.2 months, and one partial response (PR), duration 8 months. The response rate was thus 4% (95% CI: 0.5 to 14%). In addition 3 patients experienced a mixed response, some metastatic sites responding, while at other sites disease progressed; 22 patients had disease stabilization for > 2 months. A subset analysis disclosed that a small subgroup of patients, including 7 patients in this study, who had achieved CR at some of the sites during preceding tamoxifen therapy, experienced a long progression-free time during high dose toremifene treatment. The median time to progression in this subgroup of patients was 9.4 months (95% CI: 3.8 to 9.4) as opposed to 2.1 months (95% CI: 2.0 to 2.8) for all the remaining 43 patients, which is a significant decrease in disease progression (p < 0.03). Such results reveal that although this kind of second-line hormonal treatment with high dose toremifene cannot be recommended for all tamoxifen failures, there might be a subset of patients, i.e. those who achieve CR in some lesion during tamoxifen therapy, who benefit from this type of treatment.

Selegiline in de novo parkinsonian patients: the Finnish study.

Selegiline (L-deprenyl) has been recommended as an antiparkinsonian drug to be used as an adjunct to therapy with L-dopa, if and when L-dopa starts to lose its effect. However, initial selegiline monotherapy followed by L-dopa may be both effective and safe. A double-blind, placebo-controlled trial was carried out in previously untreated patients with Parkinson's disease randomized to receive selegiline (10 mg/day; 27 patients) or placebo (25 patients) until L-dopa treatment became imperative. Three rating scales were used for assessment. The study design continues to be double-blind even after L-dopa is introduced. L-Dopa was needed after 545 +/- 90 days in the selegiline group. This was significantly later (p = 0.03) than after placebo (372 +/- 28 days). Disability was less severe in the selegiline group, and there were no serious adverse effects. A nearly twofold dose of L-dopa was needed in the placebo group to achieve a sufficient therapeutic effect during long-term treatment. These results show that selegiline is safe and effective as monotherapy in early parkinsonism. It delays the need for L-dopa treatment and reduces the amount of daily L-dopa required. This could be explained by either a symptomatic effect or neuroprotective efficacy or, more likely, a combination of both.

Intramuscularly administered dexmedetomidine attenuates hemodynamic and stress hormone responses to gynecologic laparoscopy.

The hemodynamic and endocrine effects of three different doses of dexmedetomidine (0.6, 1.2, and 2.4 micrograms/kg), oxycodone (0.13 mg/kg), and saline solution, injected intramuscularly 45-60 min before induction of general anesthesia, were compared in a double-blind, randomized study involving 100 women undergoing gynecologic diagnostic laparoscopy. Anesthesia was induced with thiopental (4.5 mg/kg) and maintained with 0.3% end-tidal isoflurane and 70% nitrous oxide in oxygen. Arterial blood pressure and heart rate increased after endotracheal intubation and during laparoscopy in all groups, but the maximal mean arterial pressure after tracheal intubation was lower in the dexmedetomidine 2.4-micrograms/kg group (104 mm Hg [SD 19]) than in the saline solution group (130 mm Hg [SD 12]). Dexmedetomidine (2.4 and 1.2 micrograms/kg) attenuated the maximal heart rate after intubation (84 [SD 11] and 101 beats/min [SD 15], respectively) compared with saline solution (116 beats/min [SD 19]). On the other hand, 40% of the patients in the dexmedetomidine 2.4-micrograms/kg group received atropine in the postanesthesia care unit for bradycardia (heart rate < or = 40 beats/min). Preoperative anxiety and sedation before and after preanesthetic medication were evaluated by the patients with the aid of a profile of mood-state questionnaire; only dexmedetomidine 2.4 micrograms/kg produced significant anxiolysis and sedation. Plasma concentrations of norepinephrine, epinephrine, 3,4-dihydroxyphenylglycol, cortisol, and beta-endorphin increased less in the dexmedetomidine 2.4-micrograms/kg group in response to tracheal intubation and surgery than in the saline solution group.

Selegiline as initial treatment in de novo parkinsonian patients.

To investigate the efficacy and safety of selegiline in the early phase of Parkinson's disease (PD), we carried out a placebo-controlled, double-blind, parallel trial. De novo PD patients were randomized to receive either selegiline (10 mg/d) or matching placebo. We continued selegiline or placebo until levodopa therapy became necessary and assessed the disability using three different rating scales at baseline, after 3 weeks, at 2, 4, 8, and 12 months, and at every 4 months thereafter. Fifty-two patients were eligible for the analysis, 27 in the selegiline group and 25 in the placebo group. The median duration of time before levodopa had to be initiated was 545 +/- 90 days with selegiline and 372 +/- 28 days with placebo (p = 0.03). Disability was significantly less in the selegiline group than in the placebo group up to 12 months. The period of time during which the mean total Columbia University Rating Scale score stayed below the baseline was used to express the initial symptomatic effect of the treatments. The difference in this initial improvement time between the two groups was about 3 months and did not alone explain the difference in the delay of the need to start levodopa therapy. Selegiline was well tolerated and there were no severe side effects. We conclude that selegiline delays the need to start levodopa in de novo PD patients, has symptomatic efficacy, and possibly retards the progression of the disease.

Uptake of 2-fluoro-2-deoxy-D-[U-14C]-glucose during chemotherapy in murine Lewis lung tumor.

Mice bearing intramuscular Lewis lung tumor were treated with BCNU and doxorubicin (ADM) to study chemotherapy-induced changes in the uptake of 2-fluoro-2-deoxy-[U-14C]glucose (FDG). A decreased FDG uptake, tumor regression and a diminished proportion of aneuploid versus diploid cells as evaluated by DNA flow cytometry were seen after treatment with BCNU but not with ADM; HPLC indicated that most of the 14C activity in tumors was from FDG6-phosphate. The results suggest that changes in FDG uptake reflect the effectiveness of antitumor therapy. FDG may be valuable in follow-up studies of cancer treatment.

A comparison of dexmedetomidine, and alpha 2-adrenoceptor agonist, and midazolam as i.m. premedication for minor gynaecological surgery.

The effects of i.m. dexmedetomidine 1.0 micrograms kg-1, a new alpha 2-adrenoceptor agonist, were compared with those of i.m. midazolam 0.08 mg kg-1 and placebo on vigilance, anaesthetic requirements, haemodynamic state and plasma catecholamine concentrations in a double-blind placebo-controlled study in 107 healthy (ASA physical status I-II) women undergoing cervical dilatation and uterine curettage. The premedicants were administered i.m. 60 min before induction of anaesthesia with thiopentone. Nitrous oxide 70% in oxygen and thiopentone were used for maintenance. Both premedicants were tolerated well and no serious haemodynamic or other adverse events occurred. Dexmedetomidine caused moderate reductions in arterial pressure (maximally by 20%) and heart rate (maximally by 15%). Atropine was administered to two dexmedetomidine-premedicated patients because of bradycardia less than 45 beat min-1. Both premedicants decreased the plasma concentrations of noradrenaline by about 50%, but only dexmedetomidine attenuated the catecholamine response to anaesthesia and surgery. The thiopentone requirements were decreased significantly (P = 0.003) by both dexmedetomidine (17%) and midazolam (19%). Recovery times were 11.3 (SD 4.2) min after midazolam, 8.5 (5.2) min after dexmedetomidine and 5.6 (11.4) min after placebo (P = 0.006 between midazolam and placebo groups, other differences ns).