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PubMed1999

Short needles (8 mm) reduce the risk of intramuscular injections in children with type 1 diabetes.

OBJECTIVE: To study whether 8-mm needles can reduce the frequency of intramuscular injections in diabetic children. RESEARCH DESIGN AND METHODS: We conducted a prospective crossover study in 50 children whose BMI was < or = 60th percentile to compare two lengths of needles (12.7 and 8 mm) regarding the occurrence of intramuscular injections as assessed by ultrasonography. RESULTS: The frequency of intramuscular injections was 86% with the 12.7-mm needles and 38% with the 8-mm needles. The frequency of intramuscular injections was significantly reduced when using the 8-mm needles in the arms (P < 0.01) and thighs (P < 0.001). The efficiency of 8-mm needles, as defined by an intramuscular injection with a 12.7-mm needle and a subcutaneous injection with an 8-mm needle, was found for half of the children who injected in the arm and for two-thirds of the children who injected in the thigh. The subcutaneous tissue (SQT) thickness measured by ultrasonography with a skinfold was significantly higher (9.8 +/- 2.2 mm) in the group in which the 8-mm needles were efficient than in the group in which they were not efficient (6.8 +/- 2.1 mm, P < 0.0001). The efficiency of the 8-mm needle was not related to age, sex, BMI, percentile of BMI, injection device, or injection site. The sensibility and specificity of SQT thickness in predicting the efficiency of the 8-mm needles were both 79%. CONCLUSIONS: Needles that are 8 mm long significantly reduce the risk of intramuscular insulin injection in slim or normal-weight (BMI < or = 60th percentile) diabetic children and adolescents.

Adolescent↗
PubMed1981

Non-homologue pairing and spontaneous meiotic interchanges in Drosophila melanogaster females.

Spontaneous interchange between the X chromosomes and the C(2L) autosomal compound in their centromeric regions was studied in y/XY;C(2L);C(2R) and In(1)dl-49+BM1/XY;C(2L);C(2R) Drosophila melanogaster females. These females were mated with F(2L)/F(2L);C(2R) males. Interchange occurrence was recorded as the appearance of an F1 individual with a half-translocation of either X . 2L or Y . 2L type. 37 interchanges were recovered in y/XY and 67 in In(1)/XY females. The majority of the interchanges were of meiotic origin. The interchanges were mainly C(2L)-XY; the most frequent type of half-translocation was Y . 2L;dl-49+BM1. Inversion increased about 5-fold the interchange frequency. In the course of C(2L)-XY interchange, the other X chromosome and C(2R) compound regularly paired and disjoined. In y/XY females, 8 crossover half-translocations of meiotic origin were recovered. The results obtained indicate that meiotic pairing between the X's and C(2L) occurred in the females examined. According to our estimates, XY-C(2L) pairing is associated with interchange in the heterochromatic centromeric regions with a frequency of 10(-3). The recovery of crossover half-translocations supports the chromocentral model of non-homologous pairing and allows us to assume that a chromosome may simultaneously pair with a homologue and a non-homologue. The disjunction pattern of this trivalent depends on its structure in each particular case. The chromosome-segregation pattern resulting from spontaneous interchanges was similar to that resulting from radiation-induced interchanges in the immature oocytes described by Parker. This similarity suggests that non-homologue pairing occurs in the immature oocytes too. The non-homologue-pairing pattern established by the interchange test conformed well with that previously established in y/XY and In(1)XY females by the distribution test.

Animals↗
PubMed1976

Eterobarb therapy in epilepsy.

A group of 27 patients with various types of epilepsy were selected for a 6-month double-blind crossover study to compare the anticonvulsant effect and toxicity of eterobarb and phenobarbital. No statistically significant differences in seizure frequency were found among the 21 patients who completed the 6-month trial, but three others, in whom status epilepticus developed during the crossover from eterobarb to phenobarbital, had to be removed from the trial. The study provided some indication that when eterobarb and phenobarbital were used in high dosage with corresponding high serum barbiturate levels (over 30 mug per milliliter), eterobarb had a superior therapeutic effect. Side effects from both drugs included tiredness, sleepiness, nystagmus, and infrequently ataxia, but serious systemic toxicity did not occur. This study showed that eterobarb is a safe and potent anticonvulsant comparable in efficacy to phenobarbital, and the superior results obtained in some patients with eterobarb therapy indicate that it is an effective alternative anticonvulsant.

Adolescent↗
PubMed2006

The dynamic susceptibility in glass forming molecular liquids: the search for universal relaxation patterns II.

The susceptibility spectra of ten molecular glass formers are completely interpolated by an extension of the generalized gamma distribution of correlation times. The data cover at least 15 decades in frequency and the interpolation includes both alpha peak and excess wing. It is shown that the line shape parameters and the time constant of the alpha relaxation are related to each other. Master curves are identified by a scaling procedure that involves only three parameters, namely, the glass transition temperature T(g), the fragility m, and the excess wing exponent at T(g). This holds independent of whether a further secondary relaxation peak is present or not. Above a crossover temperature T(x) this unique evolution of the line shape parameters breaks down, and a crossover to a simple peak susceptibility without excess wing is observed. Here, the frequency-temperature superposition principle holds in good approximation up to temperatures well above the melting point. It turns out that the crossover coincides with the temperature at which the low-temperature Vogel-Fulcher law starts to fail upon heating. Thus, the so-called Stickel temperature gets a more physical meaning as it marks a qualitative change in the evolution of the susceptibility spectra of glass formers. Moreover, the interrelation of the line shape parameters can explain why the "Nagel scaling" works in some approximation. Our study demonstrates that the excess wing in molecular glass formers is a secondary relaxation, which is linked to the alpha process in a unique way.

Journal Article↗
PubMed1997

Gastrointestinal tolerance of a pediatric fiber formula in developmentally disabled children.

OBJECTIVE: We performed a masked, randomized, 2-month crossover study with developmentally disabled children to study the tolerance of a pediatric adapted enteral formula with added soy fiber. METHODS: Twenty children and adolescents aged 1 to 17 years, requiring liquid nutrition, were fed Pediasure (PS) and Pediasure with approximately 10 g total dietary fiber/l, (PSF10) as their major source of energy and nutrient intake for 1 month each. During the two 4-week periods of the crossover study, intake, tolerance of the formula, and stool characteristics were monitored daily with diaries. Criteria for gastrointestinal tolerance were symptoms of emesis, gas, irritability or fussiness. Stool characteristics included frequency, consistency, and the need to use elimination aids to induce defecation. Following completion of the crossover study, the patients were fed PSF10 for an additional 2 months. Anthropometrics were obtained at study initiation and at each biweekly visit during the crossover phase and monthly during the follow-up phase. Bowel scintigraphy studies were conducted in patients with oral or nasogastric intake during the crossover periods. Biochemical assessments were conducted at entry, at the end of each crossover period, and at exit. RESULTS: There were no differences in any of the tolerance, stooling, growth, or biochemical measurements between the feeding regimens, in 11 children completing this phase of the study. However, there was a trend towards using less elimination aids to induce a bowel movement during the fiber supplemented formula phase. CONCLUSIONS: Pediasure with fiber is well tolerated in children with developmental disabilities.

Adolescent↗
PubMed1998

Prospective evaluation of vitamin E for hot flashes in breast cancer survivors.

PURPOSE: Hot flashes represent a substantial clinical problem for some breast cancer survivors. Although estrogen or progesterone preparations can alleviate these symptoms in many patients, concern remains regarding the use of hormonal preparations in such women. Thus, there is a perceived need for nonhormonal treatments for hot flashes for breast cancer survivors. Based on anecdotal evidence that vitamin E was helpful, we designed a trial to investigate this matter. METHODS: We developed and conducted a placebo-controlled, randomized, crossover trial where, after a 1 week baseline period, patients received 4 weeks of vitamin E 800 IU daily, then 4 weeks of an identical-appearing placebo, or vice versa. Diaries were used to measure potential toxicities and hot flashes during the baseline week and the two subsequent 4-week treatment periods. RESULTS: The 120 patients evaluated for toxicity failed to show any. The 105 patients who finished the first treatment period showed a similar reduction in hot flash frequencies (25% v 22%; P = .90) for the two study arms. A crossover analysis, however, showed that vitamin E was associated with a minimal decrease in hot flashes (one less hot flash per day than was seen with a placebo) (P < or = .05). At the study end, patients did not prefer vitamin E over the placebo (32% v 29%, respectively). CONCLUSION: Although this trial was able to show a statistically significant hot flash reduction with vitamin E compared to a placebo, the clinical magnitude of this reduction was marginal.

Adolescent↗
PubMed2004

Systematic review of sacral nerve stimulation for faecal incontinence and constipation.

BACKGROUND AND METHOD: This systematic review assesses the efficacy and safety of sacral nerve stimulation (SNS) for faecal incontinence and constipation. Electronic databases and selected websites were searched for studies evaluating SNS in the treatment of faecal incontinence or constipation. Primary outcome measures included episodes of faecal incontinence per week (faecal incontinence studies) and number of evacuations per week (constipation studies). RESULTS: From 106 potentially relevant reports, six patient series and one crossover study of SNS for faecal incontinence, and four patient series and one crossover study of SNS for constipation, were included. After implantation, 41-75 per cent of patients achieved complete faecal continence and 75-100 per cent experienced improvement in episodes of incontinence. There were 19 adverse events among 149 patients. The small crossover study reported increased episodes of faecal incontinence when the implanted pulse generator was switched off. Case series of SNS for constipation reported an increased frequency of evacuation. There were four adverse events among the 20 patients with a permanent implant. The small crossover study reported a reduced number of evacuations when the pulse generator was switched off. CONCLUSION: SNS results in significant improvement in faecal incontinence in patients resistant to conservative treatment. Early data also suggest benefit in the treatment of constipation.

Constipation↗
PubMed2006

An extension of Geiringer's theorem for a wide class of evolutionary search algorithms.

The frequency with which various elements of the search space of a given evolutionary algorithm are sampled is affected by the family of recombination (reproduction) operators. The original Geiringer theorem tells us the limiting frequency of occurrence of a given individual under repeated application of crossover alone for the classical genetic algorithm. Recently, Geiringer's theorem has been generalized to include the case of linear GP with homologous crossover (which can also be thought of as a variable length GA). In the current paper we prove a general theorem which tells us that under rather mild conditions on a given evolutionary algorithm, call it A, the stationary distribution of a certain Markov chain of populations in the absence of selection is unique and uniform. This theorem not only implies the already existing versions of Geiringer's theorem, but also provides a recipe of how to obtain similar facts for a rather wide class of evolutionary algorithms. The techniques which are used to prove this theorem involve a classical fact about random walks on a group and may allow us to compute and/or estimate the eigenvalues of the corresponding Markov transition matrix which is directly related to the rate of convergence towards the unique limiting distribution.

Algorithms↗
PubMedDate not supplied

Short term effects of valproate on infantile spasms.

Although valproic acid (VPA) is used to treat infantile spasms, VPA's efficacy in infantile spasms has not been determined in a controlled study. This study evaluated the effect of VPA on infantile spasms in patients who had not responded to adrenocorticotropin (ACTH) and corticosteroid therapy. The hypotheses were tested using a double-blind, randomized controlled crossover design. Twenty-one patients were randomly assigned to either the baseline-valproate-placebo treatment or the baseline-placebo-valproate treatment groups. Based on a repeated measures analysis of variance test, the valproate group had lower total mean spasm frequency levels than the placebo group. However, this difference did not remain after the crossover; the difference was due to the initial administration of valproate and placebo. When the spasm index was analyzed, the valproate treatment was found to have lower mean spasm index scores than the baseline treatments (p less than 0.03). No short-term toxic effects were observed in any patient. We conclude that short-term VPA therapy has a beneficial effect even on chronic infantile spasm patients who have failed to respond to ACTH/corticosteroid therapy.

Clinical Trials as Topic↗
PubMed1989

Propranolol, clonidine, urapidil and trazodone infusion in essential tremor: a double-blind crossover trial.

Accelerometric tremorgrams were recorded from 25 subjects affected by essential tremor and analysed by a Berg-Fourier frequency analyser before and during venous infusion of the following drugs: propranolol (beta-blocker), clonidine (alpha-presynaptic adrenergic agonist), urapidil (alpha-postsynaptic blocker), trazodone (adrenolytic agent) and placebo. The washout interval between infusions was 3 days. Recordings and data analyses were performed in a double-blind crossover trial. Tremor was classified as: at rest; postural (arms hyperextended); and intention (finger-nose test). Analysis of the results showed that propranolol and clonidine reduced significantly (P = 0.01 and P = 0.009, respectively) the power spectrum of postural tremor, but left at rest and intention tremors unchanged. No significant effects on the tremor power spectrum were observed after placebo, urapidil or trazodone administration. None of the drugs had any effect on tremor frequency.

Adult↗
PubMed2005

High frequency induction of mitotic recombination by ionizing radiation in Mlh1 null mouse cells.

Mitotic recombination in somatic cells involves crossover events between homologous autosomal chromosomes. This process can convert a cell with a heterozygous deficiency to one with a homozygous deficiency if a mutant allele is present on one of the two homologous autosomes. Thus mitotic recombination often represents the second mutational step in tumor suppressor gene inactivation. In this study we examined the frequency and spectrum of ionizing radiation (IR)-induced autosomal mutations affecting Aprt expression in a mouse kidney cell line null for the Mlh1 mismatch repair (MMR) gene. The mutant frequency results demonstrated high frequency induction of mutations by IR exposure and the spectral analysis revealed that most of this response was due to the induction of mitotic recombinational events. High frequency induction of mitotic recombination was not observed in a DNA repair-proficient cell line or in a cell line with an MMR-independent mutator phenotype. These results demonstrate that IR exposure can initiate a process leading to mitotic recombinational events and that MMR function suppresses these events from occurring.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Mood effects of repetitive transcranial magnetic stimulation of left prefrontal cortex in healthy volunteers.

This study investigated the effect of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) of the left prefrontal cortex (LPFC) on mood in a sham-controlled crossover design. Twenty-five healthy male subjects received HF-rTMS of the LPFC in real and sham conditions. Forty trains (frequency 20 Hz, stimulation intensity 100% of individual motor threshold, train duration 2 s, intertrain interval 28 s) were applied in each session. Mood change from baseline was measured with five visual analog scales (VAS) for sadness, anxiety, happiness, tiredness and pain/discomfort. We were unable to demonstrate significant mood changes from baseline on visual analog scales after either sham or real stimulation of LPFC. There is insufficient evidence to support the general conclusion that HF-rTMS of LPFC has mood effects in healthy volunteers. Future studies should be sham-controlled, have larger sample sizes, and strictly stimulate one single region per session in order to exclude interaction effects with the previous stimulation.

Adult↗
PubMedDate not supplied

Randomized, double-blind, placebo-controlled, crossover study of sertraline (Zoloft) for the treatment of hot flashes in women with early stage breast cancer taking tamoxifen.

We observed the relief of hot flashes in breast cancer survivors taking tamoxifen and treated with sertraline for depression. Our objective was to assess the effect of sertraline on the frequency and severity of hot flashes, mood status, and health-related quality of life. We used a randomized, double-blind, placebo-controlled, crossover study using 6 weeks of sertraline (50 mg each morning) versus placebo. Study participants were 62 breast cancer survivors from an oncology clinic in a tertiary care center on adjuvant tamoxifen reporting bothersome hot flashes. Patients were asked to keep a daily hot flash diary to record hot flash frequency and severity, from which hot flash scores (frequency x severity) were calculated. The Center for Epidemiologic Studies depression scale and Functional Assessment of Cancer Therapy--Breast (FACT-B) (at baseline, 6 weeks, and 12 weeks) were used to assess mood and quality of life. Sixty-two women were accrued. Forty-seven women (median age 53.9 years, range 36.6-77.1 years; 89% postmenopausal; 85.5% Caucasian) completed the first 6 weeks and 39 completed 12 weeks. The baseline daily hot flash frequency and score were 5.8 (standard deviation 4.1) and 11.5 (14.0), respectively. At the end of the first 6 weeks, hot flash frequency decreased by 50% in 36% of those taking sertraline compared to 27% taking placebo. In the crossover analysis, sertraline was significantly more effective than placebo: women crossing from placebo to sertraline had a decrease (-0.9 and -1.7) in hot flash frequency and score, whereas those crossing from sertraline to placebo had an increase (1.5 and 3.4) in hot flash frequency and score (p = 0.03 and 0.03). Forty-eight percent preferred the sertraline period, 11% preferred the placebo period, and 41% had no preference (p = 0.006). Measures of depression and quality of life were within normal range and did not change significantly within treatment groups. Sertraline decreases hot flashes in breast cancer survivors taking tamoxifen and women prefer sertraline to placebo. Further study of sertraline for the management of hot flashes is warranted.

Adult↗
PubMed1999

Rapid onset of action of levodopa in restless legs syndrome: a double-blind, randomized, multicenter, crossover trial.

OBJECTIVE: To investigate the efficacy and safety of levodopa plus benserazide in the treatment of restless legs syndrome (RLS), in terms of the frequency of periodic limb movements (PLMs), objective and subjective criteria of sleep, onset of action, and withdrawal effects. DESIGN: A randomized, double-blind, placebo-controlled, multicenter, crossover trial, with two 4-week treatment periods. SETTING: Outpatient units of three specialist centers in Germany. PATIENTS: Eligible patients had to fulfill the diagnostic criteria of the International RLS Study Group and have sleep disturbances and PLMs during sleep shown on polysomnography at screening. Thirty-five patients were recruited, of whom 32 (13 men, 19 women) completed the study. INTERVENTIONS: Patients received a single dose of standard-release levodopa/benserazide 100/25 mg or placebo at bedtime each night for 4 weeks, before crossing over to receive the alternative treatment for a further 4 weeks; the dose could be doubled if required. The average dosages were 159 +/- 31 mg of levodopa and 1.56 +/- 0.29 capsules of placebo. RESULTS: Levodopa/benserazide significantly reduced the number of PLMs per hour (p<0.0001), increased the time in bed without limb movements (p<0.0001), and improved subjective quality of sleep (p=0.0004). The onset of action was rapid after the first dose, and full efficacy was achieved within the first few days of therapy; these improvements disappeared immediately when treatment was discontinued. Levodopa/benserazide treatment was well tolerated and safe. CONCLUSIONS: Levodopa/benserazide is effective and safe in the treatment of RLS. Objective and subjective measures of sleep improved rapidly after the first dose. RLS symptoms recurred immediately after treatment was discontinued.

Adult↗
PubMed1990

Crossing over and chromosome 21 nondisjunction: a study of 60 families.

To test the hypothesis that meiotic nondisjunction may be caused by reduced chiasma frequency, hence recombination, we investigated 60 families with a trisomic child affected with Down syndrome (DS). We analyzed cytogenetic heteromorphisms (CH) and a number of restriction fragment length polymorphisms spanning regions 11.1 through 22.3 of 21q in both parents, in the DS child and, when available (21 families), in a normal sib. The parental origin and meiotic stage of nondisjunction were determined by combining the results of both CH and RFLP analysis. Crossover events were detected as switches in the parental haplotype expected in both DS and normal sibs. Available recombination frequency data were used to calculate the expected number of crossover events in nondisjoined and in normally segregating chromosomes, given the allele combination present in each family. The observed number of crossover events in normal meioses and in second-division nondisjunctions were consistent with the calculated figures. However, a significant reduction in the observed number of crossover events was found in nondisjoined chromosomes derived from errors in the first meiotic division and, in particular, in the proximal portion of 21q.

Chromosomes, Human, Pair 21↗
PubMed1984

An analysis of regional constraints on exchange in Drosophila melanogaster using recombination-defective meiotic mutants.

The frequency of crossing over per unit of physical distance varies systematically along the chromosomes of Drosophila melanogaster. The regional distribution of crossovers in a series of X chromosomes of the same genetic constitution, but having different sequences, was compared in the presence and absence of normal genetically mediated regional constraints on exchange. Recombination was examined in Drosophila melanogaster females homozygous for either normal sequence X chromosomes or any of a series of X chromosome inversions. Autosomally, these females were either (1) wild type, (2) homozygous for one of several recombination-defective meiotic mutations that attenuate the normal regional constraints on exchange or (3) heterozygous for the multiply inverted chromosome TM2. The results show that the centromere, the telomeres, the heterochromatin and the euchromatic-heterochromatic junction do not serve as elements that respond to genic determinants of the regional distribution of exchanges. Instead, the results suggest that there are several elements sparsely distributed in the X chromosome euchromatin. Together with the controlling system affected by recombination-defective meiotic mutations, these elements specify the regional distribution of exchanges. The results also demonstrate that the alteration in the distribution of crossovers caused by inversion heterozygosity (the interchromosomal effect) results from the response of a normal controlling system to an overall increase in the frequency of crossing over, rather than from a disruption of the system of regional constraints on exchange that is disrupted by meiotic mutations. The mechanisms by which regional constraints on exchange might be established are discussed, as is the possible evolutionary significance of this system.

Animals↗
PubMed1995

Foreign complementary sequences facilitate genetic RNA recombination in brome mosaic virus.

We have demonstrated that local antisense sequences can mediate genetic recombination within the 3' noncoding region among brome mosaic virus (BMV) RNAs (P. Nagy and J. J. Bujarski, 1993, Proc. Natl. Acad. Sci. USA 90, 6390-6394). Here we show that foreign complementary inserts can direct crossovers between BMV RNA3 components within an internal region. A 170-nt polynucleotide derived from the cowpea chlorotic mottle virus (CCMV) RNA3 was inserted just upstream of the initiation codon of the BMV coat protein open reading frame in either sense or antisense orientations. The resulting respective mutants, BCC+ and BCC-, maintained unchanged CCMV inserts when inoculated separately on leaves of a local lesion host for BMV. In contrast, when a mixture containing both mutated RNAs3 was inoculated, a significant fraction of lesions accumulated the BMV RNA3 lacking the CCMV insert. The presence of a 3' marker mutation confirmed that the BMV RNA3 progeny arose due to crossovers between BCC+ and BCC- within the complementary sequences. The highest frequency of recombinant appearance was observed when the RNA mixtures were annealed prior to inoculation on the host plants. Our results confirm a concept predicting the general nature of the heteroduplex-mediated recombination functioning in RNA viruses. Examples of possible applications of this approach in recombinant RNA technology are discussed.

Antisense Elements (Genetics)↗
PubMed1994

High fidelity extrachromosomal recombination and gene targeting in plants.

The precision of extrachromosomal homologous recombination and gene targeting in plant cells was investigated. Recombination was directed to introns of selectable marker genes where potential changes could persist without affecting the function and therefore the selectability of the genes. Approximately 9 kb of crossover regions was rescued and sequenced. Changes were detected at a frequency below one point mutation per 1000 bp, indicating that extrachromosomal recombination and gene targeting both appear to occur with high fidelity.

Crossing Over, Genetic↗