A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines.

A portable synchrotron molecular beam epitaxy (MBE) system is designed and applied for in situ investigations. The growth chamber is equipped with all the standard MBE components such as effusion cells with shutters, main shutter, cooling shroud, manipulator, reflection high energy electron diffraction setup, and pressure gauges. The characteristic feature of the system is the beryllium windows which are used for in situ x-ray measurements. An UHV sample transfer case allows in vacuo transfer of samples prepared elsewhere. We describe the system design and demonstrate its performance by investigating the annealing process of buried InGaAs self-organized quantum dots.

A randomized comparison of two prophylaxis regimens and a paired comparison of on-demand and prophylaxis treatments in hemophilia A management.

BACKGROUND: Prophylaxis with factor (F)VIII is considered the optimal treatment for managing hemophilia A patients without inhibitors. OBJECTIVES: To compare the efficacy of two prophylaxis regimens (primary outcome) and of on-demand and prophylaxis treatments (secondary outcome), and to continue the evaluation of immunogenicity and overall safety of the ADVATE Antihemophilic Factor (Recombinant), Plasma/Albumin Free Method (rAHF-PFM). PATIENTS/METHODS: Previously on-demand-treated patients aged 7-59 years (n = 66) with FVIII levels ≤ 2% received 6 months of on-demand treatment and then were randomized to 12 months of either standard (20-40 IU kg(-1) every other day) or pharmacokinetic (PK)-tailored (20-80 IU kg(-1) every third day) prophylaxis, both regimens intended to maintain FVIII trough levels at or above 1%. Efficacy was evaluated in terms of annualized bleeding rates (ABRs). As subjects were first treated on-demand and then on prophylaxis, statistical comparisons between these treatments were paired. RESULTS: Twenty-two (33.3%) subjects on prophylaxis experienced no bleeding episodes, whereas none treated on-demand were free from an episode of bleeding. ABRs for the two prophylaxis regimens were comparable, whereas differences between on-demand and either prophylaxis were statistically significant (P < 0.0001): median (interquartile range [IQR]) ABRs were 43.9 (21.9), 1.0 (3.5), 2.0 (6.9) and 1.1 (4.9) during on-demand treatment, standard, PK-tailored and any prophylaxis, respectively. There were no differences in FVIII consumption or adverse event rates between prophylaxis regimens. No subject developed FVIII inhibitors. CONCLUSIONS: The present study demonstrates comparable safety and effectiveness for two prophylaxis regimens and that prophylaxis significantly reduces bleeding compared with on-demand treatment. PK-tailored prophylaxis offers an alternative to standard prophylaxis for the prevention of bleeding.

Trends in bleeding patterns during prophylaxis for severe haemophilia: observations from a series of prospective clinical trials.

Replacement therapy or prophylaxis, has become the standard of care for the treatment of severe haemophilia A. To describe bleeding patterns in children, adolescents and adults on prophylaxis and their observed relationships to times of infusion (during the week and during the day) as well as season of the year. Data from Advate pre-licensure prospective clinical trials from 145 patients with factor VIII (FVIII) <1%, were used. All patients underwent a 48-h pharmacokinetic study. The 10-65 year group had ≥ 75 exposure days on fixed prophylaxis (25-40 IU kg(-1) 3-4x per week). Prophylaxis was not fixed but similar for 1-6 year olds. Bleeding patterns were analysed. Overall, 700 bleeds were observed in 110/145 patients. All were treated with prophylaxis, mean dose 108 IU kg(-1) week(-1) in on average 2.9 infusions (1-6 years), 86 IU kg (-1) week(-1) in 2.7 infusions (10-17 years), and 75 IU kg (-1) week(-1) in 2.6 infusions (18-65 years), respectively. On prophylaxis, median total bleeds per year were low at 3.1 for patients aged 1-6 years, 3.3 for those aged 10-17 years and 2.1 for patients aged 18-65 years. Patients aged 1-6 years had predominantly soft tissue bleeds (79%). Incidence of joint bleeding was not associated with season, but was significantly lower in patients who infused FVIII in the mornings: median 0 per year (IQR 0.0-0.4) compared to those who infused later [median 1.8 per year (IQR 0.0-5.2)]. Older patients predominantly experienced joint bleeds (50% and 62%, respectively). More joint bleeds occurred during the summer [43 and 46% respectively, (P < 0.01)]. Bleeding patterns in patients on prophylaxis varied according to age. In addition, the 10-65 year olds showed increased bleeding during the summer. After confirmation in prospective studies, this information may be used to improve tailoring of prophylactic treatment.

Comparative pharmacokinetics of plasma- and albumin-free recombinant factor VIII in children and adults: the influence of blood sampling schedule on observed age-related differences and implications for dose tailoring.

BACKGROUND: Dose tailoring of coagulation factors requires reliably estimated and reproducible pharmacokinetics (PK) in the individual patient. OBJECTIVES: To investigate the contribution of both biological and methodological factors to the observed variability of factor VIII (FVIII) PK, with the focus on differences between children and adults, and to examine the implications for dosing. PATIENTS: Data from 52 1-6-year-old and 100 10-65-year-old patients with hemophilia A (FVIII < or = 2 IU dL(-1)) in three clinical studies were included. RESULTS: In vivo recovery was lower, weight-adjusted clearance was higher and FVIII half-life was on average shorter in children than in adults. However, a reduced blood sampling schedule for children was estimated to account for up to one half of the total observed differences. Intrapatient variance in PK was smaller than interpatient variance in 10-65-year-olds. Age and ratio of actual to ideal weight only showed weak relationships with PK parameters. Variance in PK caused large variance in the calculated dose required to maintain a target FVIII trough level during prophylactic treatment. CONCLUSION: Differences in blood sampling schedules should be taken into account when results from different PK studies are compared. However, even with this consideration, PK cannot be predicted from observable patient characteristics but must be determined for the individual. Because the influence of reducing the blood sampling was minor in comparison to the true variance between patients, a reduced blood sampling protocol can be used. Low intrapatient variability supports the use of PK measurements for dose tailoring of FVIII.

Factor VIII requirement to maintain a target plasma level in the prophylactic treatment of severe hemophilia A: influences of variance in pharmacokinetics and treatment regimens.

BACKGROUND: Prophylactic factor (F)VIII has been shown to reduce bleeds and arthropathy in patients with severe hemophilia A. OBJECTIVES: Assuming that the trough FVIII level is an important determinant of the efficacy of prophylaxis, this paper addresses the effect of the inter-patient variability in pharmacokinetics and different dosing regimens on trough levels. METHODS: Simulations used FVIII half-lives and in vivo recoveries (IVR), observed during clinical trials with Advate [Antihemophilic Factor (Recombinant), Plasma/Albumin-Free Method], and commonly used prophylactic regimens to calculate their effect on FVIII levels during prophylaxis. RESULTS AND CONCLUSIONS: Half-life and dose frequency had a larger effect on trough FVIII and time per week with FVIII<1 IU dL(-1) than IVR and infused dose per kg. The combined effect of these parameters resulted in substantial inter-patient variability in the amount of FVIII required to sustain a desired trough level. Prophylactic regimens based on Monday, Wednesday, Friday dosing were less cost effective in maintaining a desired trough level throughout the week. Dose escalation on Friday to cover the weekend would require potentially harmful doses of FVIII in many patients, especially in young children where more than 50% would require a Friday dose of over 100 IU kg(-1) and some would require more than 400 IU kg(-1). Knowledge of individual patients' half-lives and alteration of frequency of infusions may allow the more cost-effective use of FVIII and potentially expand access to prophylaxis to a greater number of patients, especially in regions where healthcare resources are scarce.

Break-through bleeding in relation to predicted factor VIII levels in patients receiving prophylactic treatment for severe hemophilia A.

BACKGROUND: The role of prophylactic factor VIII (FVIII) to decrease hemophilic bleeding and arthropathy is well established. The rationale for this strategy is to convert patients with severe hemophilia A to a moderate clinical phenotype by reducing time spent with a FVIII level <1 IU dL(-1). Studies to date, however, have not demonstrated a strong link between FVIII level and the bleeding rate. OBJECTIVES: To assess the effect of FVIII level on break-through bleeding in patients with severe hemophilia A on prophylaxis. PATIENTS/METHODS: This study analysed data from 44 patients aged 1-6 and 99 patients aged 10-65 years with severe hemophilia A (FVIII <1 IU dL(-1)) who were treated with prophylactic FVIII as part of clinical studies assessing pharmacokinetics, safety and efficacy of a recombinant FVIII (Advate). Each patient had pharmacokinetic measurements and FVIII infusions recorded, and these were used to calculate time spent with a FVIII below 1, 2 and 5 IU dL(-1). RESULTS: The data demonstrate that increasing time with a FVIII below 1 IU dL(-1) is associated with increased total bleeds and hemarthroses. Lack of adherence to the intended frequency of FVIII infusion was the most important determinant of low FVIII and increased bleeding. In children aged 1-6 years, the rate of bleeding was also influenced by FVIII half-life and clearance. CONCLUSIONS: These data have important implications for the management of patients with severe hemophilia.

Plasma and albumin-free recombinant factor VIII: pharmacokinetics, efficacy and safety in previously treated pediatric patients.

BACKGROUND: The pharmacokinetics of factor VIII replacement therapy in preschool previously treated patients (PTPs) with hemophilia A have not been well characterized. OBJECTIVES: To assess the pharmacokinetics, efficacy and safety of a plasma-free recombinant FVIII concentrate, ADVATE [Antihemophilic Factor (Recombinant), Plasma/Albumin-Free Method, rAHF-PFM], in children < 6 years of age with severe hemophilia. PATIENTS/METHODS: Fifty-two boys, one girl, mean (+/- SD) age 3.1 +/- 1.5 years and >or= 50 days of prior FVIII exposure, were enrolled in a prospective study of ADVATE rAHF-PFM at 23 centers. RESULTS: The mean terminal phase half-life (t(1/2)) was 9.88 +/- 1.89 h, and the mean adjusted in vivo recovery (IVR) was 1.90 +/- 0.43 IU dL(-1) (IU kg(-1))(-1). Over the 1-6-year age range, t(1/2) of rAHF-PFM increased by 0.40 h year(-1). IVR increased by 0.095IU dL(-1)(IU kg(-1))(-1) (kg m(-2))(-1) in relation to body mass index (BMI). Patients primarily received prophylaxis. Median (range) annual joint bleeds were 0.0 (0.0-5.8), 0.0 (0.0-6.1) and 14.2 (0.0-34.5) for standard prophylaxis, modified prophylaxis and on-demand treatment, respectively. Bleeds were managed in 90% (319/354) of episodes with one or two rAHF-PFM infusions; response was rated excellent/good in 93.8% of episodes. Over a median 156 exposure days, no FVIII inhibitors were detected and no related severe adverse events or unusual non-serious adverse events were seen. CONCLUSIONS: Children < 6 years of age appear to have shorter FVIII t(1/2) and lower IVR values than older subjects. However, these parameters increased with age (t(1/2)) and BMI (adjusted IVR), respectively. rAHF-PFM was clinically effective and well tolerated, with no signs of increased immunogenicity in previously treated young children with hemophilia A.

Thymus and myasthenia gravis: antigen processing in the human thymus and the consequences for the generation of autoreactive T cells.

Peptides displayed by antigen presenting cells in the thymus shape the T cell repertoire. We investigated the antigen processing machinery of the MHC class II presentation pathway and describe the differential expression of lysosomal proteases in compartments of the thymus and the peripheral lymphoid tissue. Overexpression of certain proteases found in the thymus and thymoma associated with myasthenia gravis is likely to affect tolerance induction and may promote the generation autoreactive CD4(+) T helper cells.

Clinical evaluation of an advanced category antihaemophilic factor prepared using a plasma/albumin-free method: pharmacokinetics, efficacy, and safety in previously treated patients with haemophilia A.

The efficacy and safety of an advanced category recombinant antihaemophilic factor produced by a plasma- and albumin-free method (rAHF-PFM) was studied in 111 previously treated subjects with haemophilia A. The study comprised a randomized, double-blinded, crossover pharmacokinetic comparison of rAHF-PFM and RECOMBINATE rAHF (R-FVIII); prophylaxis (three to four times per week with 25-40 IU kg(-1) rAHF-PFM) for at least 75 exposure days; and treatment of episodic haemorrhagic events. Median age was 18 years, 96% of subjects had baseline factor VIII <1%, and 108 received study drug. Bioequivalence, based on area under the plasma concentration vs. time curve and adjusted in vivo recovery, was demonstrated for rAHF-PFM and R-FVIII. Mean (+/-SD) half-life for rAHF-PFM was 12.0 +/- 4.3 h. Among 510 bleeding events, 473 (93%) were managed with one or two infusions of rAHF-PFM and 439 (86%) had efficacy ratings of excellent or good. Subjects who were less adherent to the prophylactic regimen had a higher bleeding rate (9.9 episodes subject(-1) year(-1)) than subjects who were more adherent (4.4 episodes subject(-1) year(-1); P < 0.03). One subject developed a low titre, non-persistent inhibitor (2.0 BU) after 26 exposure days. These data demonstrate that rAHF-PFM is bioequivalent to R-FVIII, and suggest that rAHF-PFM is efficacious and safe, without increased immunogenicity, for the treatment of haemophilia A.

Pharmacokinetics of recombinant factor VIII (recombinate) using one-stage clotting and chromogenic factor VIII assay.

In a study designed to demonstrate the safety and pharmacokinetics of a recombinant factor VIII (Recombinate) manufactured in Andover, MA and Thousand Oaks, CA, two different methods of factor VIII assay (one-stage clotting and Chromogenic substrate) were compared in vivo. The study was performed in four centres in the UK: London, Oxford, Cardiff and Manchester. Two pharmacokinetic studies, at least one week apart, were performed in 30 patients with severe haemophilia A (VIII:C < 2 IU/dl). A dose of 50 IU/kg was administered with sampling pre-infusion, and +0.25, 0.5, 1, 3, 6, 9, 12 and 24 h post-infusion. The aggregate 60 pharmacokinetic study showed a half-life of 12.7 and 13.0 h (p = 0.28) and recovery of 127 and 161 IU/dl (p = 0.0001) using one-stage clotting or chromogenic substrate respectively. In a supplementary experiment, 20 post-infusion samples were re-assayed by 1-stage and chromogenic assay using two plasma (20th British plasma standard and an "in-house" pooled normal plasma) and two concentrate standards, derived from the same type, but different batch of infused concentrate (Recombinate) and pre-diluted in either individual pre-infusion sample or in pooled commercial haemophilic plasma. The use of the Recombinate concentrate standard overcame the significant difference in FVIII levels between 1-stage and chromogenic assay methods when a plasma standard was used (p <0.0001). It is concluded that where potency dosing designation is carried out by an assay system different to that used in the clinical situation, the use of the recombinant concentrate as a standard in post-infusion plasma samples is likely to give more reliable and reproducible results.

Insect-based BioFETs with improved signal characteristics.

Insect-based BioFETs (biologically sensitive field-effect transistors) with improved signal characteristics have been developed. These BioFETs require a specifically adapted signal interfacing between a FET as signal transducer and an intact insect antenna as biocomponent. Therefore, different field-effect transistors have been fabricated in order to study the signal transfer at the bioelectronic interface. As relevant features of the BioFET, its current-voltage characteristics, the transconductance and the signal-to-noise ratio have been investigated as affected by the choice of gate insulator materials and gate dimensions (width-to-length ratio, thickness of the dielectric layers). The performance of the improved FET arrangement in the isolated-antenna BioFET was validated by employing dilution series of the plant odour component Z-3-hexen-1-ol.

1-C-glucuronidation of N-nitrosodiethylamine and N-nitrosomethyl-n-pentylamine in vivo and in primary hepatocytes from rats pretreated with inducers.

The organ specificity of the carcinogenic action of nitrosamines is partly explained by organ specific activation. The specificity might also be determined by conjugation of reactive intermediates in e.g. the liver. 14C-Labeled N-nitrosodiethylamine (NDEA) a liver carcinogen and N-nitrosomethyl-n-pentylamine (NMPentA) which induces esophageal and nasal tumors were administered to rats or incubated with primary cells. Urine and cell extracts were separated by HPLC after addition of synthetic marker glucuronides and these were quantified by liquid scintillation counting. In urine of rats treated with NDEA 0.03% of administered nitrosamine was recovered as the O-glucuronide derived from N-nitroso-1-hydroxyethylethylamine. In rats treated with NMPentA 2.86% was metabolized to the glucuronide at the methyl group. In hepatocytes of untreated rats 0.03% of the added NDEA was conjugated to the glucuronide, phenobarbital pretreatment induced this conjugation reaction 5-fold. Hepatocytes from untreated rats metabolized 1.2% of NMPentA to the primary glucuronide; after phenobarbital pretreatment this value increased to 1.6%. In hepatocytes from 3-methylcholanthrene-pretreated rats, 0.04% of NMPentA was metabolized to the glucuronide derived from N-nitroso-1-hydroxy-n-pentyl-methylamine, while 0.85% was derived from N-nitroso-hydroxymethyl-n-pentylamine. In hepatocytes from Aroclor-pretreated rats, 0.09% were pentyl conjugates and 1.1% methyl conjugates. The induction pattern and organ specificity of glucuronidation indicate that all three 1-hydroxy nitrosamines are conjugated by group II phenobarbital inducible UDP-glucuronosyltransferase activity. The lipophilicity of a nitrosamine seems to determine the extent of glucuronidation in hepatocytes and in vivo. No glucuronides derived from either NDEA or NMPentA were detectable in incubations with kidney cells, nor was the glucuronide of NDEA found in incubations with whole bladders.

Dietary restriction on serum thyroid hormone levels.

To determine the long term effects of a protein sparing fast on serum thyroid hormone levels, the authors studied 38 obese patients ingesting a diet of 320 kcal for up to 13 weeks. The high baseline serum triiodothyronine (T3) levels decreased significantly by the first week, further decreased by the third week, and this lower level persisted for the duration of the fast until realimentation. Serum free T3 index followed the same general pattern as did serum T3 levels. Serum reverse T3 increased significantly by the first week, but by week three, the reverse T3 level had begun to fall, although still significantly increased above baseline. By week seven, reverse T3 had decreased to almost baseline and remained not significantly changed from the baseline to 13 weeks. Serum thyroxine (T4) increased significantly by the first week in all patients, but by the third week had returned to baseline levels which persisted to 13 weeks. The free T4 index and free T4 concentrations showed the same increment at week one and then returned to baseline levels. There were no significant changes in serum thyroxine-binding globulin (TBG) or thyroid-stimulating hormone (TSH) concentrations. The changes in serum T3 and reverse T3 levels are attributable to alterations in peripheral 5'-monodeiodination of T4 and reverse T3 induced by the protein sparing fast.

Psychometric assessment of first-degree relatives of 62 autistic probands in Utah.

The Wechsler Intelligence Scales, Wide Range Achievement Test, and the Shipley-Hartford Test were administered to 122 parents and 153 siblings of 62 autistic probands in Utah. Scores were distributed as expected within the published normative ranges for each scale. Parents' scores correlated with those of their nonautistic children, but neither parents' nor siblings' scores correlated with the IQ level of the autistic probands. These results do not confirm prior reports from England and the United States of a high rate of cognitive and learning problems in the siblings of autistic individuals, nor the aggregation of such problems in the siblings of probands with high or low levels of cognitive function.

Maternal serum alpha-fetoprotein screening of fetal trisomies.

Thirty-two trisomy pregnancies were retrospectively studied in which the maternal serum level of alpha-fetoprotein was determined prior to amniocentesis. Median levels of alpha-fetoprotein in serum (0.83 multiples of the median) and in amniotic fluid (0.72 multiples of the median) were lowered, but this was statistically significant only in the case of amniotic fluid.

Obesity and hypertension: long-term effects of weight reduction on blood pressure.

Long-term follow-up studies were conducted on massively obese hypertensive subjects during and after a successful protein supplemented fast (PSMF) in order to correlate blood pressure changes with caloric intake and body weight. The blood pressures in 43 subjects were compared during rapid weight loss and at identical weights during post-fast weight gain (Study A). Blood pressures and body weights in 50 subjects were compared prior to starting PSMF and prior to restarting the program 21 months later (Study B). One hundred twenty-five compliant subjects were observed after one month of weight maintenance (Study C-1), and 39 subjects were followed during six months of weight maintenance (Study C-2). In Study A, during subsequent weight gain on an unrestricted diet blood pressure was significantly higher than at identical weight during continuous weight loss on PSMF. However, this increase in blood pressure was only approximately 30 percent of the original decrease. In Study B, weight loss and blood pressure reduction were significantly correlated. After one month of weight maintenance following continuous weight loss of 73 lb, there was no increase in blood pressure (Study C-1). A small but significant increase in blood pressure after six months (Study C-2) was associated with similar small weight increment. However, all blood pressures remained well within the normotensive range and significantly lower than control values. In this study, long-term changes in blood pressure correlated with changes in body weight.

Study of fenfluramine in outpatients with the syndrome of autism.

Fenfluramine was administered to 14 outpatient children with the syndrome of autism to determine whether previously produced decreases in blood serotonin concentrations and clinical improvements could be reinstituted. A double-blind medication-placebo crossover design was used. Each patient received fenfluramine 1.5 mg/kg daily (0.75 mg/kg twice daily) for 8 months, followed by placebo for 2 months. Blood serotonin levels promptly fell approximately 49% regardless of baseline levels. Clinical improvement returned, and on some scales gains after 8 months exceeded those noted after only 4 months of treatment. Significant correlations emerged among the amount of clinical response, initially high verbal IQs, and low blood serotonin concentrations. Compliance was excellent, and no clinically relevant side effects or weight changes occurred. It appears that fenfluramine is effective in ameliorating specific symptoms in certain autistic patients. The extent and mechanism of its action remain to be discovered.