Rapid changes in corticospinal excitability during force field adaptation of human walking.

Force field adaptation of locomotor muscle activity is one way of studying the ability of the motor control networks in the brain and spinal cord to adapt in a flexible way to changes in the environment. Here, we investigate whether the corticospinal tract is involved in this adaptation. We measured changes in motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in the tibialis anterior (TA) muscle before, during, and after subjects adapted to a force field applied to the ankle joint during treadmill walking. When the force field assisted dorsiflexion during the swing phase of the step cycle, subjects adapted by decreasing TA EMG activity. In contrast, when the force field resisted dorsiflexion, they increased TA EMG activity. After the force field was removed, normal EMG activity gradually returned over the next 5 min of walking. TA MEPs elicited in the early swing phase of the step cycle were smaller during adaptation to the assistive force field and larger during adaptation to the resistive force field. When elicited 5 min after the force field was removed, MEPs returned to their original values. The changes in TA MEPs were larger than what could be explained by changes in background TA EMG activity. These effects seemed specific to walking, as similar changes in TA MEP were not seen when seated subjects were tested during static dorsiflexion. These observations suggest that the corticospinal tract contributes to the adaptation of walking to an external force field.

Afferent contribution to locomotor muscle activity during unconstrained overground human walking: an analysis of triceps surae muscle fascicles.

Plantar flexor series elasticity can be used to dissociate muscle-fascicle and muscle-tendon behavior and thus afferent feedback during human walking. We used electromyography (EMG) and high-speed ultrasonography concomitantly to monitor muscle activity and muscle fascicle behavior in 19 healthy volunteers as they walked across a platform. On random trials, the platform was dropped (8 cm, 0.9 g acceleration) or held at a small inclination (up to +/-3 degrees in the parasagittal plane) with respect to level ground. Dropping the platform in the mid and late phases of stance produced a depression in the soleus muscle activity with an onset latency of about 50 ms. The reduction in ground reaction force also unloaded the plantar flexor muscles. The soleus muscle fascicles shortened with a minimum delay of 14 ms. Small variations in platform inclination produced significant changes in triceps surae muscle activity; EMG increased when stepping on an inclined surface and decreased when stepping on a declined surface. This sensory modulation of the locomotor output was concomitant with changes in triceps surae muscle fascicle and gastrocnemius tendon length. Assuming that afferent activity correlates to these mechanical changes, our results indicate that within-step sensory feedback from the plantar flexor muscles automatically adjusts muscle activity to compensate for small ground irregularities. The delayed onset of muscle fascicle movement after dropping the platform indicates that at least the initial part of the soleus depression is more likely mediated by a decrease in force feedback than length-sensitive feedback, indicating that force feedback contributes to the locomotor activity in human walking.

Oxygen stress: a regulator of apoptosis in yeast.

Oxygen radicals are important components of metazoan apoptosis. We have found that apoptosis can be induced in the yeast Saccharomyces cerevisiae by depletion of glutathione or by low external doses of H2O2. Cycloheximide prevents apoptotic death revealing active participation of the cell. Yeast can also be triggered into apoptosis by a mutation in CDC48 or by expression of mammalian bax. In both cases, we show oxygen radicals to accumulate in the cell, whereas radical depletion or hypoxia prevents apoptosis. These results suggest that the generation of oxygen radicals is a key event in the ancestral apoptotic pathway and offer an explanation for the mechanism of bax-induced apoptosis in the absence of any established apoptotic gene in yeast.

Identifying the causal mechanisms of the quiet eye.

Scientists who have examined the gaze strategies employed by athletes have determined that longer quiet eye (QE) durations (QED) are characteristic of skilled compared to less-skilled performers. However, the cognitive mechanisms of the QE and, specifically, how the QED affects performance are not yet fully understood. We review research that has examined the functional mechanism underlying QE and discuss the neural networks that may be involved. We also highlight the limitations surrounding QE measurement and its definition and propose future research directions to address these shortcomings. Investigations into the behavioural and neural mechanisms of QE will aid the understanding of the perceptual and cognitive processes underlying expert performance and the factors that change as expertise develops.

Thermoconditional modulation of the pleiotropic sensitivity phenotype by the Saccharomyces cerevisiae PRP19 mutant allele pso4-1.

The conditionally-lethal pso4-1 mutant allele of the spliceosomal-associated PRP19 gene allowed us to study this gene's influence on pre-mRNA processing, DNA repair and sporulation. Phenotypes related to intron-containing genes were correlated to temperature. Splicing reporter systems and RT-PCR showed splicing efficiency in pso4-1 to be inversely correlated to growth temperature. A single amino acid substitution, replacing leucine with serine, was identified within the N-terminal region of the pso4-1 allele and was shown to affect the interacting properties of Pso4-1p. Amongst 24 interacting clones isolated in a two-hybrid screening, seven could be identified as parts of the RAD2, RLF2 and DBR1 genes. RAD2 encodes an endonuclease indispensable for nucleotide excision repair (NER), RLF2 encodes the major subunit of the chromatin assembly factor I, whose deletion results in sensitivity to UVC radiation, while DBR1 encodes the lariat RNA splicing debranching enzyme, which degrades intron lariat structures during splicing. Characterization of mutagen-sensitive phenotypes of rad2Delta, rlf2Delta and pso4-1 single and double mutant strains showed enhanced sensitivity for the rad2Delta pso4-1 and rlf2Delta pso4-1 double mutants, suggesting a functional interference of these proteins in DNA repair processes in Saccharomyces cerevisiae.

The in vivo effects of PIXY321 therapy on human monocyte activity.

In this report we describe the time-dependent effects of PIXY321 (a synthetic hybrid cytokine) treatment (500 and 750 micrograms/m2/day for 14 days) on six sarcoma patients. Blood was taken prior to PIXY321 injection (day 0), on days 1, 7, and 14 of treatment, and 7 days posttreatment (day 21). The number of isolated monocytes quadrupuled by day 7 and sustained a significant increase through day 14. There were significant increases in the percentage of circulating monocytes relative to total mononuclear cells on days 1 and 7 of therapy. There were no significant changes in monocyte cell surface antigens (15 checked), suggesting that the increase in monocyte numbers was not due to increased numbers of immature monocytes. The basal activity of the monocytes was not markedly altered during treatment; however, they were primed for significantly increased phorbol 12,13-dibutyrate-stimulated superoxide anion production and endotoxin-stimulated release of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) on days of 1 and 7 of therapy. There was a significant increase of IL-1 beta mRNA levels (unstimulated cells) on days 1 and 7, but TNF-alpha mRNA levels increased significantly on day 1 only. Consistent with the increase in superoxide anion production, there were increases in monocyte protein kinase C (PKC) levels on all days of therapy. There was a significant increase in PKCII beta mRNA only on the first day of treatment. All significant changes in monocyte number and function produced by PIXY321 infusion were reversible, as there were no sustained effects on day 21 (7 days after therapy). These results indicate that the effects of PIXY321 may be mediated through up-regulation of PKC resulting in monocytes primed for increased functional activity in response to an appropriate second stimulus.

Psychosocial status of children with diabetes in the first 2 years after diagnosis.

OBJECTIVE: The purpose of this study was to determine the pattern of adjustment over time of a cohort of children with newly diagnosed diabetes compared with a cohort of peer-selected children without diabetes over the first 2 years after the diagnosis of insulin-dependent diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS: Children (n = 89 with IDDM, n = 53 without IDDM) ages 8-14 years were studied with the Children's Depression Inventory, State-Trait Anxiety Inventory for Children, Child and Adolescent Adjustment Profile, Self-Perception Profile for Children, and a general health scale. Initial data were collected within 6 weeks of the diagnosis of IDDM and at 3, 6, 12, and 24 months thereafter. RESULTS: There were no demographic differences between the two groups. Initially, children with diabetes were more depressed, more dependent, and more withdrawn than their peers. By 1 year postdiagnosis, there were no significant differences in psychosocial status between the two groups. By 2 years postdiagnosis, depression, dependency, and withdrawal were significantly higher in children with diabetes than in their peers without IDDM. Self-perceived competence remained similar between the two groups at all time points. CONCLUSIONS: After an initial period of adjustment, children with IDDM have equivalent psychosocial status to children without IDDM, but by 2 years after diagnosis, they have experienced twice the amount of depression and adjustment problems as their peers. Interventions should be aimed at this critical period between 1 and 2 years postdiagnosis.

Short-term effects of coping skills training as adjunct to intensive therapy in adolescents.

OBJECTIVE: Given the urgent need to develop effective programs that improve the ability for adolescents to achieve metabolic control equivalent to programs studied in the Diabetes. Control and Complications Trial, we have undertaken a clinical trial to determine if a behavioral intervention (coping skills training [CST]) combined with intensive diabetes management can improve metabolic control and quality of life in adolescents implementing intensive therapy regimens. RESEARCH DESIGN AND METHODS: A total of 65 youths between the ages of 13 and 20 years, who elected to initiate intensive insulin therapy, were randomly assigned to one of two groups: the intensive management with CST group and the intensive management without CST group. CST consists of a series of small group efforts designed to teach adolescents the coping skills of social problem-solving, social skills training, cognitive behavior modification, and conflict resolution. Data were collected at pre-intervention and at 3 months following the use of the Self-Efficacy for Diabetes scale, Children's Depression Inventory, Issues in Coping with IDDM scale, and the Diabetes Quality of Life: Youth scale. Clinical data (HbA1c, adverse effects) were collected monthly. RESULTS: The experimental and control groups were comparable on all measures at baseline. Results show that adolescents who received CST had lower HbA1c and better diabetes self-efficacy and were less upset about coping with diabetes than adolescents receiving intensive management alone. In addition, adolescents who received the CST found it easier to cope with diabetes and experienced less of a negative impact of diabetes on quality of life than those who did not receive CST. CONCLUSIONS: CST is useful in improving not only an adolescent's metabolic control, but also their quality of life. As more pediatric providers aim for improved control, in adolescents with diabetes, the addition of this behavioral intervention may be helpful in achieving metabolic and life goals.

Personal and family factors associated with quality of life in adolescents with diabetes.

OBJECTIVE: Quality of life is an important criterion for assessing outcomes of treatment in chronic illness related to psychosocial well-being. The purpose of this study was to evaluate the factors that influence quality of life in adolescents with IDDM. RESEARCH DESIGN AND METHODS: Self-reports were obtained from 52 adolescents (age 13-20 years, mean 16.1 +/- 1.9 [mean +/- SD], diabetes duration 8.2 +/- 3.4 years, 49% female) using the following scales: Diabetes Quality of Life for Youths, Children's Depression Inventory, Issues in Coping with Diabetes, Diabetes Family Behavior Scale, Family Adaptability and Cohesion, Self-Efficacy for Diabetes, and the Adolescent Coping Orientation. Metabolic control was measured by HbA1c. RESULTS: Teenagers whose diabetes had the greater impact (R2 = 0.48) and were less satisfied (R2 = 0.45) felt that management was more difficult (r = 0.56) and that diabetes was more upsetting (r = 0.63). They also used fewer rebellion strategies for coping (r = -0.44), had lower diabetes self-efficacy (r = -0.36), and had more depressive symptoms (r = 0.61). Higher impact was also associated with higher family warmth and caring (r = -0.54) and lower family adaptability (r = -0.42). Teenagers who were more worried (R2 = 0.37) about their diabetes felt that management was more difficult (r = 0.40) and that diabetes was more upsetting (r = 0.58), and they used less rebellion (r = -0.49) and more ventilation (r = 0.42) to cope, had lower diabetes (r = -0.40) and medical (r = -0.30) self-efficacy, were more depressed (r = 0.55), and their families were less warm and caring (r = -0.33). HbA1c levels were not associated with quality of life or any other psychosocial factors except in teenagers who perceived their families as providing more guidance and control. These teenagers had lower HbA1c values than those whose families were less involved. CONCLUSIONS: Even teenagers who are successfully achieving HbA1c goals of therapy may perceive diabetes as having a negative impact on their lives, be depressed, and find diabetes difficult to manage. Diabetes treatment teams need to pay equal attention to the psychosocial needs to the quiet, nonrebellious teen with well-controlled diabetes from a supportive family as they do to the rebellious adolescent with poorly controlled diabetes.

Continuous subcutaneous insulin infusion. A new way to lower risk of severe hypoglycemia, improve metabolic control, and enhance coping in adolescents with type 1 diabetes.

OBJECTIVE: Recommendations from the Diabetes Control and Complications Trial (DCCT) indicate that adolescents with type 1 diabetes should be treated with intensive therapy involving multiple daily injections (MDI) of insulin or insulin pump therapy (continuous subcutaneous insulin infusion [CSII] to help obtain better metabolic control and prevent later complications. Interest has thus focused on insulin pump therapy to help adolescents meet this challenge. The purpose of this study was to examine responses to CSII and MDI in a large group of adolescents with established type 1 diabetes during a 12-month period and to determine whether either treatment regimen more favorably affected clinical and psychosocial outcomes. RESEARCH DESIGN AND METHODS: One-third of 75 youths aged 12-20 years who were candidates for intensive therapy chose CSII as their mode of treatment. Patients received intensive treatment and education as described by the DCCT investigators. Psychosocial data (e.g., quality of life, depression, self-efficacy, and coping) were collected at baseline and at 6-month intervals, and clinical data (e.g., HbA1c levels, adverse events) were collected every 4-6 weeks. RESULTS: Although both MDI- and CSII-treated adolescents initially exhibited improved metabolic control, this level of control was more difficult to sustain for 12 months in the MDI group (at 6 months HbA1c = 8.1, at 12 months HbA1c = 8.3), whereas average HbA1c levels in the CSII group continued to decrease during the 12 months of treatment (at 6 months HbA1c = 7.7, at 12 months HbA1c = 7.5). Despite lower HbA1c levels in CSII-versus MDI-treated patients, the rate of severe hypoglycemic events was reduced by almost 50% in the CSII group (P = 0.01). Self-reported questionnaires demonstrated that there was improvement in self-efficacy, depression, and quality of life in both MDI- and CSII-treated patients. Finally, adolescents using CSII found coping with diabetes to be less difficult than adolescents using MDI did. CONCLUSIONS: CSII is an alternative means to lower HbA1c levels and reduce the risk of hypoglycemia without adversely affecting psychosocial outcomes in adolescents with type 1 diabetes.

A microbiological assay for the quantitative determination of glutathione.

Based on the requirement of a glutathione-deficient mutant strain of Saccharomyces cerevisiae to take up external glutathione for growth on synthetic media, a simple agar diffusion test for quantitative detection of total glutathione from various sources was established. Glutathione concentrations can be reliably detected in a less expensive way, requiring less technical effort compared to enzymatic or biochemical detection methods.

Psychosocial adjustment of latency-aged diabetics: determinants and relationship to control.

The relationship of psychosocial adjustment, family functioning, self-esteem, and diabetic control was studied in 20 latency-aged diabetic children and their parents. Moderate to severe adjustment problems were found in 11 (55%) of the patients. Child self-esteem, parental self-esteem, and family functioning, as scored by standard instruments, were all significantly greater in the group of children considered to be well-adjusted as compared to the maladjusted group (P less than .05 to .001). Of these, parental self-esteem appeared to correlate most closely with the child's adjustment. Twenty-four-hour urinary glucose excretion was two- to threefold greater in maladjusted as compared to well-adjusted patients (71 +/- 20 vs 20 +/- 5 gm, P less than .05). These data suggest that psychosocial adjustment problems frequently occur in latency-aged children with diabetes, are associated with poorer chemical control, and require a family-centered approach to intervention and management.

Effect on cell kill of addition of multidrug resistance modifiers cyclosporin A and PSC 833 to cytotoxic agents in chronic lymphocytic leukaemia.

Expression of P-glycoprotein (Pgp), the drug efflux pump which mediates multidrug resistance (MDR), has been widely reported in chronic lymphocytic leukaemia (CLL) and improved accumulation of daunorubicin has been reported using the MDR reversing agent cyclosporin A (CSA). We have investigated the effects on cell kill of the addition of CSA and its analogue PSC 833 to daunorubicin, doxorubicin, idarubicin, mitozantrone and fludarabine in samples from 51 patients with CLL using an MTT [3(4,5-dimethylthaizol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Pgp expression was assessed by immunocytochemistry using the JSB-1 monoclonal antibody. Of the 51 samples, 10 (20%) were Pgp positive and all of these samples were from treated patients. With the exception of mitozantrone, the addition of CSA and PSC 833 to cytotoxic agents failed to significantly improve cytotoxicity, even in the Pgp positive group. With mitozantrone significant responses were seen in both Pgp positive and negative groups suggesting that the responses were due to direct cytotoxicity of the cytotoxic-modifier combination rather than reversal of MDR. Both CSA and PSC 833 showed significant direct cytotoxicity (P = 0.004 and 0.04 for PSC 833 at 1000 ng/ml and 500 ng/ml respectively; P < 0.001 for both concentrations of CSA). The responses were disappointing compared to the highly significant improvements in cytotoxicity seen using cells from the Pgp positive CEM VLB 100 acute myeloid leukaemia cell line, and it was not possible to demonstrate the superiority of PSC 833 over CSA which is also seen in cell lines. Our data do not support a role for Pgp modifiers in CLL. Further studies using larger numbers of Pgp positive CLL cells and higher doses of PSC 833 would be useful.

Effect on cell kill of addition of multidrug resistance modifiers cyclosporin A and PSC 833 to cytotoxic agents in acute myeloid leukaemia.

Multidrug resistance (MDR) mediated by the drug efflux pump P-glycoprotein (Pgp), may cause remission failure and relapse in patients with acute myeloid leukaemia (AML) by extruding cytotoxic agents such as anthracyclines from leukaemic cells thus allowing them to survive. Cell line data suggest that reversal of MDR is possible using modifying drugs such as cyclosporin A (CSA) and its analogue PSC 833. We have investigated the effects on cell kill of the addition of CSA and PSC 833 to daunorubicin, idarubicin, mitozantrone, etoposide and cytarabine in 52 fresh cell samples from AML patients using an MTT assay. Pgp status was determined by using monoclonal antibodies JSB-1 and MRK-16 and by assessment of rhodamine efflux. Although overall each cytotoxic-modifier combination produced significant improvements in cell kill compared to cytotoxic alone (P values ranged from P < 0.001 to P = 0.017), modifiers also produced significant cytotoxicity in their own right, and no consistent difference was seen between responses in Pgp-positive and negative groups. Up to one in three Pgp-positive samples failed to show any improvement in cell kill with the addition of CSA or PSC 833, possibly owing to co-expression of alternative resistance mechanisms not affected by the MDR modifiers. The best responses were seen when PSC 833 was added to idarubicin, with 7 out of 22 Pgp-positive cases (32%) showing five-fold improvements in cell kill or better compared to idarubicin alone. Comparison of equimolar concentrations of the two modifiers in the Pgp positive group failed to show a significant difference in cell kill, though PSC 833 was markedly superior to CSA in a minority of highly responsive samples which demonstrated clear evidence of MDR reversal. Our in vitro data suggest that MDR modifiers such as CSA and PSC 833 could play an important role in the therapy of AML and indicate the need for prospective randomised trials to assess their clinical efficacy.

Urinary tract changes associated with exposure in utero to diethylstilbestrol.

Intravenous pyelograms were performed on 128 women who had been exposed in utero to diethylstilbestrol (DES). For comparison, intravenous pyelograms (IVPs) of 48 non-exposed women were reviewed: No difference in urinary tract abnormalities was noted. There was no significant increase in urinary tract abnormalities in women with upper genital tract abnormalities demonstrated by hysterosalpingogram as compared to a group of women whose x-rays of the uterus were normal.

Immunoreactive bombesin and calcitonin paracrine cells of human fetal and newborn airways.

Lung tissue samples from 35 human fetuses (8 to 25 weeks gestation) and 18 newborn infants (25 to 41 weeks gestation who survived less than 28 days) were examined by light and transmission electron microscopy for the presence of Kulchitsky-like cells and for the peptide hormones IR bombesin and IR calcitonin. K-like cells were found in developing intrapulmonary conducting airways from bronchi through alveolar ducts, appearing both as single cells and in large clusters. IR bombesin was rarely found in bronchioles of fetuses in the first trimester, but by the second trimester K-like cells were readily identified in bronchioles, and a few were seen in alveolar ducts and bronchi. They were especially numerous in infants dying with post-respirator lung disease. IR calcitonin was not found until 20 weeks' gestation, and was also most common in post-respirator lung disease. The role of these hormones in the fetal and neonatal lung is at present unknown.

SNG1--a new gene involved in nitrosoguanidine resistance in Saccharomyces cerevisiae.

We have molecularly characterized the SNG1 gene that confers hyper-resistance to the mutagen N-methyl-N'nitro-N-nitrosoguanidine (MNNG) in Saccharomyces cerevisiae when overexpressed on a multi-copy plasmid. This hyper-resistance to MNNG is not due to depletion of glutathione pools since multi-copy SNG1 containing yeast transformants contain at least wild type levels of glutathione; DNA repair seems unaffected in these transformants as the multi-copy SNG1-mediated MNNG hyper-resistance is also seen in DNA repair mutants belonging to each of the three epistasis groups of yeast repair mutants. It could be shown that SNG1 is not under control of the YAP1 encoded transcription activator that controls expression of at least two genes involved in MNNG metabolism in yeast. sng1 null mutants are viable but exhibit only slight sensitivity to MNNG, indicating that SNG1 does not encode a protein involved in a major detoxification step of this mutagen. Sequencing of the HYR-mediating passenger DNA revealed that SNG1 encodes a 547 a polypeptide containing seven transmembrane-spanning regions that may be membrane-bound. Comparison of the DNA sequence with established gene databanks revealed that SNG1 is a novel yeast gene.

Clinical and psychosocial factors associated with achievement of treatment goals in adolescents with diabetes mellitus.

PURPOSE: To examine the following questions with regard to the initiation of a new intensive management program for adolescents with Type 1 diabetes mellitus: (a) What clinical and psychosocial factors are associated with achievement of metabolic control treatment goals after 1 year? and (b) What baseline clinical and psychosocial factors are associated with improvement in the quality of life after 12 months? METHODS: Eighty-one subjects (of 83 who began; aged 14.3 +/- 2.0 years at entry; 48 females, 33 males; 95% white; diabetes duration 8.9 +/- 3.9 years) with Type 1 diabetes completed 12 months of follow-up in a study of intensified treatment of diabetes. Assessments at baseline and at 12 months used the Diabetes Quality of Life for Youth scale, the Self-efficacy for Diabetes Scale, the Children's Depression Inventory, the Issues in Coping with Diabetes Scale, and the Diabetes Family Behavior Scale. Data were analyzed using multiple and logistic regression. RESULTS: From a baseline of >9%, HbA1c levels decreased to a mean of 7.8 +/- 0.7%, with 30% of the subjects achieving our treatment goal of

A primer on the use of insulin pumps in adolescents.

Optimal metabolic control to minimize long-term complications is a major treatment goal for adolescents with diabetes mellitus. Reaching this goal is extremely challenging in this population due to unique physiological changes and psychosocial variables that affect metabolic control. Continuous subcutaneous insulin infusion (CSII) may be an excellent treatment alternative for selected adolescents to help overcome some of these challenges. CSII allows for minute insulin changes at variable times throughout the day, providing greater lifestyle flexibility. The purpose of this paper is to review the use of insulin pump therapy in adolescents. Specific strategies regarding screening, initiation, and maintenance of this therapy are described, and case examples are used for illustration. Implications for nursing practice and diabetes education are discussed.

Coping strategies of school-age children with diabetes mellitus.

School-age children (N = 43) with insulin-dependent diabetes mellitus were studied to determine if the coping strategies they used were associated with their self-care management and/or with their metabolic control. Instruments used included the Schoolagers Coping Strategy Inventory and the Self-care Questionnaire. Results indicated that the choice of coping strategies did not differ by demographic characteristics, and level of self-care was not associated with metabolic control. Participants used cognitive coping strategies most often; higher frequencies tended to be associated with higher levels of self-care and metabolic control. Those who utilized distracting strategies also tended to have higher levels of self-care. Emotional coping strategies tended to be related to poorer metabolic control. The use of coping strategies explained approximately 18% of the variance in metabolic control. These data suggest that healthcare providers should assess what coping strategies are employed by school-age children with diabetes because the choice of strategies may have a significant impact on their metabolic control. The use of strategies related to poorer metabolic control (eg, emotional strategies) should be discouraged, and the use of more effective strategies related to higher levels of self-care and metabolic control (eg, cognitive strategies) should be modeled and encouraged.