Insulin sensitivity and body composition in children with classical and nonclassical congenital adrenal hyperplasia

BACKGROUND

Reduced insulin sensitivity and increased fat mass have been reported in children and adults with congenital adrenal hyperplasia (CAH). To understand the potential mechanisms underlying these differences, we assessed insulin sensitivity and body composition in children with classical or nonclassical (late-presenting) CAH compared with normal controls.

SUBJECTS AND METHODS

Thirty-seven children with CAH (26 classical and 11 nonclassical) median (range) age 9.4 year (0.5-15.8) were compared with 41 healthy control children age 11.0 year (3.2-17.1). All children had an overnight fasting blood sample and body composition assessed by DEXA. Pubertal children (14 CAH and 19 controls) also had an oral glucose tolerance test. Classical and nonclassical CAH groups were each compared with controls, adjusting for age, gender and pubertal status. Results Classical CAH children had more fat mass than controls (P = 0.03), while nonclassical CAH children had more lean mass (P = 0.006) and higher systolic blood pressure (P = 0.003) than control children. Among pubertal children, nonclassical CAH children had higher mean insulin (0-120 min; P = 0.04), stimulated insulin (0-30 min; P = 0.02), 120 min insulin (P = 0.004) and 120 min glucose levels (P = 0.03) than controls, but no difference in disposition index.

DISCUSSION

Greater body fat in classical (early-presenting) CAH children could reflect the effects of lifetime glucocorticoid therapy. In contrast, the greater lean mass and parameters of insulin resistance in nonclassical (late-presenting) CAH children likely indicate the adverse metabolic effects of prolonged postnatal androgen excess.

Injection anxiety remains a long-term barrier to medication adherence in multiple sclerosis

OBJECTIVE

To evaluate the contribution injection anxiety to disease modifying therapy (DMT) adherence among individuals with multiple sclerosis (MS). Injection anxiety has been associated with medication discontinuation early in the course of treatment, but little is known about the relationship between injection anxiety and sustained DMT adherence over time.

METHOD

Eighty-nine outpatients receiving care at a Veterans Administration MS clinic completed a telephone survey at baseline and monthly telephone follow-up for 6 months.

RESULTS

Participants were established DMT users (M = 3.43 years, SD = 3.29), with relatively high adherence overall (over 80% achieved 80% adherence or greater). Using logistic regression and controlling for demographics, MS disability, type of DMT, and time on DMT, the authors found that baseline injection anxiety predicted lower levels of adherence at 4 months and 6 months, with a similar trend at 2 months.

CONCLUSION

Sustained adherence to DMT remains a challenge for a subset of individuals with MS well beyond the initial period of acclimation. Injection anxiety is an important and promising target of psychological intervention during all periods of medication use.

A two-year longitudinal study of social support following amputation

PURPOSE

(1) To describe one aspect of social support, social integration, longitudinally for 2 years following lower limb amputation and (2) to explore the impact of social support on depression, pain interference, life satisfaction, mobility, and occupational functioning.

METHOD

Eighty-nine adults recruited from consecutive admissions to an orthopaedic surgery service completed telephone interviews 1, 6, 12 and 24 months following amputation surgery. Dependent variables included the Social Integration (SI) sub-scale of the Craig Handicap Assessment and Reporting Technique (CHART) and the Multidimensional Scale of Perceived Social Support (MSPSS).

RESULTS

There was a high level of SI among most persons following lower limb amputations that was relatively unchanged in the 2 years following surgery. However, mean levels of SI were lower in this group compared to a sample without disabilities. MSPSS scores were highly variable, ranging from almost no support to the maximum amount of support. MSPSS was an important concurrent predictor of pain interference, life satisfaction, and mobility, controlling for demographic and amputation-related factors. Baseline MSPSS predicted mobility and occupational functioning 6 months post-amputation, controlling for demographic and amputation-related factors.

CONCLUSIONS

Findings suggest that interventions aimed at improving the quality of social relationships after amputation may facilitate participation in activities.

Effectiveness of workplace rehabilitation interventions in the treatment of work-related low back pain: A systematic review

PURPOSE

A systematic review was conducted to evaluate the effectiveness of workplace rehabilitation interventions for injured workers with low back pain (LBP).

METHOD

MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), EMBASE, and AMED (Allied and Complementary Medicine) were searched from 1982 to 2005 for peer-reviewed studies of rehabilitation interventions that were provided at the workplace to workers with musculoskeletal work-related LBP. Methodological quality appraisal and data extraction were conducted by five reviewers.

RESULTS

Of a total of 1,224 articles that were identified by the search, 15 articles, consisting of 10 studies, were of sufficient quality to be included in the review. The best evidence was that clinical interventions with occupational interventions as well as early return to work/modified work interventions were effective in returning workers to work faster, reducing pain and disability, and decreasing the rate of back injuries. Ergonomic interventions also were found to be effective workplace interventions.

CONCLUSION

The need for further research in this area is necessary to reduce the burden of back pain on employees and their families, employers, and the health care system.

A longitudinal assessment of the effect of inhaled fluticasone propionate therapy on adrenal function and growth in young children with asthma

OBJECTIVE

Fluticasone proprionate (FP) is increasingly used to treat very young children with asthma. Its safety in terms of effects on the hypothalamic pituitary axis (HPA) and growth in this age group is uncertain.

PATIENTS AND METHODS

Eleven children (median (range) age 10 (5.6-24.3) months) presenting with recurrent wheeze and family history of asthma were studied prospectively for a period of 18 months. Children received daily-inhaled FP 250 microg via a spacer device. No other corticosteroid therapy was administered prior to or during the study. A Short Standard Synacthen Test (SST) (125 microg) was performed pretreatment, and after 6 and 18 months. Weight (Wt), height (Ht), and body mass index (BMI) were measured at 3-6 monthly intervals.

RESULTS

Fasting early morning and peak cortisol levels remained within the normal reference range with therapy. There were no changes in Ht SDS, whereas both Wt SDS (baseline 0.05 (-2.17 to 0.52) vs. +18 months 0.68 (-0.5 to 1.36) P < 0.02) and BMI SDS (-0.22 (-1.73 to 0.75) vs. 0.86 (0.03 to 1.99) P < 0.005) increased after 18 months of treatment.

CONCLUSION

Daily treatment with inhaled FP 250 microg in young children with asthma appears to have no adverse effects on the HPA or on linear growth, however, treatment is associated with increases in body Wt and BMI in young children.

Depression and multiple sclerosis: Review of a lethal combination

Depression is the most frequent psychiatric disorder in multiple sclerosis (MS) patients. The etiology of depression is multifactorial and likely associated with psychosocial stress, focal demyelinating lesions, and immune dysfunction. Proper diagnosis and severity assessment are critical prior to initiation of therapy. Patients with suicidal ideation should be referred for immediate psychiatric consultation and be closely monitored. While more therapeutic trials for depression in MS are needed, MS patients have been shown to respond to current antidepressant medications and psychotherapy. Unfortunately, patients with MS and major depression or suicidal thoughts are often underassessed and therefore not diagnosed. Unlike other aspects of MS, depression is treatable. Early intervention in depression can prevent declines in quality of life and even death from suicide. This article reviews the unique features, assessment, and treatment of depression in MS. MS care providers should vigilantly assess depression and suicide risk in their patients.

Exploring educational needs of multiple sclerosis care providers: Results of a care-provider survey

Our objective was to survey experienced multiple sclerosis (MS) care providers, determine their ongoing professional educational needs, and develop future education programs. We asked providers across a variety of disciplines to identify the areas in which clinical consultation and continuing medical education (CME) would most improve their ability to provide care to individuals with MS; their preferred education modalities; and their confidence in providing care related to disease-modifying agents (DMAs), fatigue, depression, spasticity, and bladder management. At a national meeting of MS professionals, 152 MS care providers completed a self-report survey that was designed for this cross-sectional cohort study. Areas of greatest interest for clinical consultation and CME were identical and included cognition, fatigue, DMA use, spasticity, pain, sex, diagnosis of MS, and depression. Participants expressed a preference for live and interactive CME modalities. Confidence in providing specific disease-related care sometimes differed between Veterans Health Administration (VHA) and non-VHA providers. The results indicate that clinical consultations and CME should be targeted to the topics of greatest interest identified by providers and delivered in a live or interactive modality whenever possible.

Suicidal Ideation in Multiple Sclerosis

OBJECTIVE

To examine risk factors for suicidal ideation among people with multiple sclerosis (MS).

DESIGN

Cohort study linking computerized medical records with a mailed self-report survey.

SETTING

Veteran's Health Administration (VHA) region covering the northwestern United States.

PARTICIPANTS

VHA patients with MS (N=445) who returned mailed surveys.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Suicidal ideation is assessed by the Patient Health Questionnaire (PHQ) suicide item with suicidal ideation more than half the days considered persistent.

RESULTS

One hundred thirty-one (29.4%) of 445 respondents (95% confidence interval [CI], 25.4%-33.9%) endorsed suicidal ideation, and 35 (7.9%; 95% CI, 5.7%-10.8%) endorsed persistent suicidal ideation over the last 2 weeks. In bivariate analyses, suicidal ideation was associated with younger age, earlier disease course, progressive disease subtype, lower income, not being married, lower social support, not driving, higher levels of physical disability (mobility, bowel, bladder), and depression. Analyses on persistent suicidal ideation yielded similar results. In fully adjusted multivariate logistic regression, only depression severity and bowel disability were independently associated with suicidal ideation. Only depression severity was independently associated with persistent suicidal ideation. By using the 2-question depression screen (U.S. Preventive Services Task Force) consisting of the depression and anhedonia items from the PHQ-9, sensitivity and specificity were marginal for suicidal ideation (65.6% and 79.9%) but acceptable for persistent suicidal ideation (88.6% and 71.2%).

CONCLUSIONS

Suicidal ideation is common among VHA patients with MS, and depression severity is the best risk marker. Brief screening for depression in MS should include the assessment of suicidal ideation.

Does Having a Computerized Prosthetic Knee Influence Cognitive Performance During Amputee Walking?

OBJECTIVE

To compare objective cognitive performance and perception of cognitive burden during walking tasks using 2 different prosthetic knees: a computerized hydraulic knee (Otto Bock C-leg) and a noncomputerized hydraulic knee (Ossur Mauch SNS).

DESIGN

Two-group crossover trial, with participants randomly assigned to order of prosthesis. Participants completed assessments under 2 conditions, a self-selected speed walk and a controlled speed walk, on 2 separate occasions (precrossover, postcrossover).

SETTING

Veterans Health Administration hospital.

PARTICIPANTS

Eight transfemoral amputees.

INTERVENTION

Computerized versus noncomputerized prosthetic knee.

MAIN OUTCOME MEASURES

Objective cognitive performance measures included verbal fluency (Controlled Oral Word Association Test, Category Test), attention and working memory (serial subtraction), and walking speed during cognitive tasks. Measures of perceived cognitive burden included subjective attentional requirements of walking and cognitive tasks and subjective general cognitive burden of prosthesis.

RESULTS

There were no significant differences in objective cognitive performance on any task between prostheses, nor did walking speed vary by prosthesis during the free-speed walk. Participants reported that walking required less attention while wearing the C-leg and that the C-leg was less of a cognitive burden than the noncomputerized prosthesis.

CONCLUSIONS

In nondemanding walking conditions with experienced amputees, participants reported that the more costly C-leg required less cognitive attention than the noncomputerized knee. However, this subjective experience did not translate to improved performance on neuropsychologic screening instruments or on walking speed. Noncomputerized prostheses may be adequate for a majority of amputees, and further research is needed to identify particular groups of amputees (ie, new amputees, amputees with complex physical or cognitive demands) who may benefit from computerized prostheses.

Prosthetic Intervention Effects on Activity of Lower-Extremity Amputees

OBJECTIVE

To investigate the effect of prosthetic interventions on the functional mobility of lower-extremity amputees.

DESIGN

Crossover with repeated measures.

SETTING

Household and community environment.

PARTICIPANTS

Twelve transtibial and 5 transfemoral amputees.

INTERVENTIONS

For transtibial amputees, shock-absorbing versus rigid pylons. For transfemoral amputees, C-Leg versus Mauch SNS knees.

MAIN OUTCOME MEASURES

Daily activity level (step count) and duration (minutes of activity).

RESULTS

Pylon type had no effect on the daily activity level or duration of transtibial amputees. Knee type had no effect on the daily activity level or duration of transfemoral amputees. Transtibial amputees were more active on weekdays (3079+/-1515 steps/d) than weekends (2386+/-1225 steps/d) (P=.007). In general, lower-extremity amputees perform numerous short-duration bouts of activity (1-2 min) consisting of fewer than 17 steps/min, but activities of more than 15 minutes in duration were relatively rare (<1 per day).

CONCLUSIONS

Intervention had no effect on amputee activity level and duration. Higher weekday activity levels of transtibial amputees suggest their vocational activities are more demanding than recreational activities. The fitting, alignment, and design of prosthetic components should be optimized for 1 to 2 minute bouts of activity consisting of only a few dozen steps.

Complementary and alternative medicine use in veterans with multiple sclerosis: Prevalence and demographic associations

The present study explored complementary and alternative medicine (CAM) use in veterans with multiple sclerosis (MS). We administered self-report questionnaires to 451 veterans who received healthcare from Veterans Health Administration facilities. CAM use among veterans with MS was widespread; 37% of respondents reported current or past use. Roughly 33% of CAM users reported using multiple interventions, and 40% of respondents desired interventions that they were not already using. Logistic regression suggested that CAM use was more likely among participants with graduate-level education, poor self-reported health over the past year, and a progressive relapsing MS subtype. Participants who used traditional medical services were also more likely to use CAM, which suggests that CAM services are used in addition to, as opposed to in place of, traditional services. As others have proposed, these results suggest that care providers who work with persons with MS would be well served to understand, routinely screen for, and make use of CAM when appropriate.

Predictors of prescriptions for management of fatigue among veterans with multiple sclerosis

OBJECTIVE

To determine predictors of fatigue-modifying medication use.

DESIGN

Cross-sectional cohort.

SETTING

Veterans Health Administration (VHA) facilities.

PARTICIPANTS

Veterans with multiple sclerosis (MS) in the VHA in the northwestern United States from 1995 to 2000.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A self-administered survey distributed by mail sought information from veterans with MS about demographics, symptoms, barriers to care, and disease characteristics. The variables were compared with prescriptions for fatigue-modifying medications during the study period.

RESULTS

Of 1032 patients, 451 (44%) completed the survey, and 306 (68%) reported moderate or high fatigue levels. Only 40% of the 306 were prescribed fatigue-modifying medications. Those using specialized fatigue services or who received care at tertiary centers were more likely to receive fatigue treatments. Patient-perceived barriers to accessing care and other patient characteristics were not associated with prescription rates.

CONCLUSIONS

Fatigue is undertreated among veterans with MS. However, there is considerable variability in the provision of fatigue care. Interventions to improve the quality and uniformity of fatigue care are warranted.

Prevalence and correlates of depression among veterans with multiple sclerosis

OBJECTIVES

To establish the prevalence of major depressive episode (MDE) in a large sample of veterans with multiple sclerosis (MS); to identify demographic characteristics, aspects of disease presentation, and perceptions of disability associated with greater concurrent risk for MDE; and to examine the relationship between MDE, service utilization, and activity participation.

METHODS

Veterans with MS (n = 1,032) were identified via computer database and surveyed by mail; 451 (43.7%) responded.

RESULTS

Twenty-two percent of the sample met criteria for current MDE. Low income, unemployment, presence of falls, younger age, absence of a marital partner, and high levels of perceived disability due to bowel functioning were independently associated with MDE. Disease subtype, disease duration, use of disease modifying therapies, and perceived disability due to mobility or bladder problems were unrelated to MDE. Current MDE was in turn associated with increased primary care visits and increased impact of disease upon activity participation. Similar correlates were associated with minor depressive episode.

CONCLUSIONS

Unlike the general population, rates of depression in this predominantly male sample were similar to those found in predominantly female samples of persons with multiple sclerosis. Specific aspects of disability were differentially associated with depression, and depression was independently associated with increased service utilization and increased participation limitations.

Group-Based Psychotherapy for Military Veterans with Multiple Sclerosis

This paper describes the development of a program of group-based psychosocial services offered to patients with multiple sclerosis at a Veteran's Health Administration facility. Four groups are currently offered: “Living Well with MS,” “Enhancing Cognitive Skills,” “Enhancing Interpersonal Relationships and Managing Mood,” and “Caregiver Support.” The theoretical and practical evolution of these groups is discussed, along with suggestions to assist mental health professionals in designing similar group programs at their facilities. The principles described are appropriate for persons with a variety of physical and cognitive impairments.

Insulin treatment in children and adolescents

The management of diabetes in children presents a number of challenges. The ideal is to achieve optimal glycaemic control using an insulin regimen that is acceptable to the child and family, which improves glycaemic control, whilst avoiding hypoglycaemia. The paediatric population differ from their adult counterparts in several ways, such as variability of exercise and eating patterns, and the hormonal influences of puberty, which means that the insulin regimen must be tailored to suit an individual child and their family.

CONCLUSION

This review will focus on the particular difficulties of managing diabetes in children and, in particular, the problem of avoiding hypoglycaemia while maintaining adequate glycaemic control.

Identifying undiagnosed dementia in residential care veterans: comparing telemedicine to in-person clinical examination

BACKGROUND

Dementia is a common but frequently undiagnosed problem in aging. Barriers to early diagnosis include a lack of routine screening for dementia and a lack of access to specialty consultative services. We conducted a pilot study to see if telemedicine could provide reliable, accurate geriatric consultative services to evaluate patients for dementia who were residing at remote sites.

METHODS

This was a prospective cohort study that compared the diagnostic reliability of telemedicine to an in-person examination for dementia. Eligible subjects were residents of a Washington State Veterans' Home, age 60 years or older, with no prior diagnosis of dementia. Eligible subjects were screened for dementia using the 7-Minute Screen. Veterans who screened positive and consented to participate in the study received an in-person neuropsychiatric evaluation at baseline, and then both telemedicine and in-person examinations for dementia conducted by experienced geriatric psychiatrists. The accuracy of the telemedicine diagnosis was estimated by comparing it to the diagnosis from the clinical examination. Three geriatric psychiatrists who were blinded to the results of the clinical examination conducted the telemedicine and in-person examinations. We also assessed attitudes of the subjects and geriatric psychiatrists towards the telemedicine sessions.

RESULTS

Eighteen of 85 subjects screened were 'positive' for dementia on the 7 Minute Screen. Of these, 16 consented to participate in the telemedicine study. Twelve of the 16 subjects were subsequently diagnosed with dementia by the telemedicine examination. The telemedicine diagnoses were in 100% agreement with the diagnoses from the in-person clinical examinations. Moreover, the subjects reported a high degree of satisfaction with the telemedicine experience and that they would like to have further care through telemedicine in the future. The geriatric psychiatrists reported technical difficulties with the audio-visual quality of telemedicine in the initial phases of the project that resolved as familiarity with the telemedicine equipment increased. None of these problems had an adverse impact on the diagnostic accuracy of telemedicine.

CONCLUSIONS

We found that telemedicine was as accurate as an in-person clinical examination in establishing the diagnosis of dementia. In addition, subjects reported a high degree of satisfaction with telemedicine and a willingness to participate in telemedicine clinical care in the future. Given the large increase in the aging population and the shortage of geriatric psychiatrists nationally, it appears that telemedicine may be a promising means to expand the availability of geriatric psychiatric consultation to remote areas.

The effects of a specific growth hormone antagonist on overnight insulin requirements and insulin sensitivity in young adults with Type 1 diabetes mellitus

AIMS/HYPOTHESIS

Growth hormone hypersecretion in Type 1 diabetes could exacerbate insulin resistance and contribute to declining glycaemic control. Our aim was to determine the effects of specific growth hormone blockade on insulin sensitivity and lipolysis in young adults with Type 1 diabetes.

METHODS

We studied the effects of two doses of a specific growth hormone antagonist (B2036-PEG; Somavert, Pharmacia Corporation, Milton Keynes, UK) on insulin sensitivity in seven young adults (17-22 yrs, 3M) with Type 1 diabetes. Subjects received 5 and 10 mg B2036-PEG, in random order for 3 weeks, with a 3-week washout. At baseline and following each treatment block, an overnight (03:00 to 08:00 h) insulin infusion for euglycaemia (5 mmol/l), followed by two-step hyperinsulinaemic euglycaemic clamp, using [6,6 2H2] glucose and 2H5 glycerol to measure glucose and glycerol turnover was performed.

RESULTS

Compared to baseline, overnight insulin requirements decreased with both doses: (means+/-SEM) 0.34+/-0.02 mU/Kg/min vs 0.25+/-0.01 (5 mg) (p=0.04), and 0.24+/-0.01 (10 mg) (p=0.004). IGF-I (ng/ml) decreased following 10 mg [223.5+/-23.9 vs 154.6+/-28.1 (p=0.005], but not 5 mg. Mean overnight non esterified fatty acid concentrations (mmol/l) decreased with 10 mg [0.51+/-0.04 vs 0.38+/-0.04 (p=0.03)], as did beta-hydroxybutyrate (mmol/l); [0.31+/-0.04 vs 0.15+/-0.02 (p=0.004)]. Glycerol production rate, an index of lipolysis, was lower following 10 mg (p=0.04), but insulin sensitivity during the clamp did not change with either dose.

CONCLUSION/INTERPRETATION

Treatment with both doses of B2036-PEG reduced overnight insulin requirements. The 10 mg dose suppressed lipolysis and reduced IGF-I. Failure to show enhanced insulin sensitivity during the clamp with the 10 mg dose could reflect opposing actions of growth hormone and IGF-I.

In-utero androgen exposure and 2nd to 4th digit length ratio-comparisons between healthy controls and females with classical congenital adrenal hyperplasia

BACKGROUND

Soft tissue measurements from the hand reveal lower second to fourth finger digit ratios (2D:4D) in males compared with females. The relatively longer 4th finger observed in males may be related to increased fetal exposure to androgens influencing the expression of Hox genes.

METHODS

We have measured 2D:4D ratios in 69 healthy females [median age 9.3 (range 1.9-17) years], 77 control males [median age 13.86 (2.1-20.3) years] and in 66 females with classical virilizing congenital adrenal hyperplasia (CAH) (median age 8.5 (1.1-16.2) years] who are known to be exposed to high concentrations of androgens in utero. Measurements were determined from X-rays of the left hand using vernier callipers. Intra-observer variability in measurement technique was 0.01%.

RESULTS

Control males had a significantly lower mean (SD) 2D:4D ratio [0.918 (0.029)] compared with female patients [0.927 (0.029), ANOVA P = 0.02]. No difference in 2D:4D ratio was observed between CAH females [0.925 (0.021)] and control females [0.927 (0.029)]. In contrast, 2D:4D ratio in males were significantly lower compared with CAH females (P = 0.03).

CONCLUSIONS

2D:4D ratios determined directly from radiographs of the left hand confirm significant differences between males and females. However, female patients with virilizing CAH do not have a male digit ratio pattern suggesting that in the left hand digit ratio development is not influenced by in-utero exposure to androgens.

Evaluation of a peer consultation program for burn inpatients. 2000 ABA paper

A burn survivor may provide unique psychological support to patients who have been burned more recently and enhance their adjustment to burn injury. The purpose of this study was to describe the peer consultation/burn survivor support program at a large regional burn center in the Northwest United States. Over the course of 17 months, three specially trained peer consultants who had survived their own burn injuries in the past made 167 visits to 108 patients, who, in turn, completed evaluation forms for each visit. Findings indicated that patients reported that the peer consultants approached them in an appropriate manner, answered their questions, and provided useful support and information.

The yeast lifecycle and DNA array technology

The genome variability and meiotic gene expression patterns in two unrelated laboratory yeast strains, SK1 and W303, have been characterized using high-density oligonucleotide arrays. The statistical analysis and comparison of the data has allowed identification of: (1) genes with functional importance to meiosis and sporulation in yeast and (2) genes expressed in a strain-specific manner. The genome-wide data also reveal potential reasons why these strains display significant differences in the ability to make fertile spores. Molecularly tagged yeast deletion strains have been used to determine the contribution of each gene to the execution of the sporulation/germination pathway. The application of genetics and the new genomic technologies have allowed a quantum jump in our understanding of yeast molecular biology.

Free-running frequency stability of mid-infrared quantum cascade lasers

The intrinsic frequency fluctuations of two single-mode quantum cascade (QC) distributed-feedback lasers operating continuously at a wavelength of 8.5 mum are reported. A Doppler-limited rovibrational resonance of nitrous oxide is used to transform the frequency noise into measurable intensity fluctuations. The QC lasers, along with recently improved current controllers, exhibit a free-running frequency stability of 150 kHz over a 15-ms time interval.

Intrinsically disordered protein

Proteins can exist in a trinity of structures: the ordered state, the molten globule, and the random coil. The five following examples suggest that native protein structure can correspond to any of the three states (not just the ordered state) and that protein function can arise from any of the three states and their transitions. (1) In a process that likely mimics infection, fd phage converts from the ordered into the disordered molten globular state. (2) Nucleosome hyperacetylation is crucial to DNA replication and transcription; this chemical modification greatly increases the net negative charge of the nucleosome core particle. We propose that the increased charge imbalance promotes its conversion to a much less rigid form. (3) Clusterin contains an ordered domain and also a native molten globular region. The molten globular domain likely functions as a proteinaceous detergent for cell remodeling and removal of apoptotic debris. (4) In a critical signaling event, a helix in calcineurin becomes bound and surrounded by calmodulin, thereby turning on calcineurin's serine/threonine phosphatase activity. Locating the calcineurin helix within a region of disorder is essential for enabling calmodulin to surround its target upon binding. (5) Calsequestrin regulates calcium levels in the sarcoplasmic reticulum by binding approximately 50 ions/molecule. Disordered polyanion tails at the carboxy terminus bind many of these calcium ions, perhaps without adopting a unique structure. In addition to these examples, we will discuss 16 more proteins with native disorder. These disordered regions include molecular recognition domains, protein folding inhibitors, flexible linkers, entropic springs, entropic clocks, and entropic bristles. Motivated by such examples of intrinsic disorder, we are studying the relationships between amino acid sequence and order/disorder, and from this information we are predicting intrinsic order/disorder from amino acid sequence. The sequence-structure relationships indicate that disorder is an encoded property, and the predictions strongly suggest that proteins in nature are much richer in intrinsic disorder than are those in the Protein Data Bank. Recent predictions on 29 genomes indicate that proteins from eucaryotes apparently have more intrinsic disorder than those from either bacteria or archaea, with typically > 30% of eucaryotic proteins having disordered regions of length > or = 50 consecutive residues.

Asymmetric synthesis of (+)-hypusine

Wittig reaction of (triphenylphosphoranylidene)acetonitrile with the lactone carbonyl of (5R,6S)-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-one (3) and subsequent reduction generates morpholinylethylamine dihydrochloride (5) in quantitative yield and with excellent diastereoselectivity. Compound 5 was readily converted into hypusine dihydrochloride (1.2HCl) in overall 53% yield. [reaction: see text]

Asymmetric synthesis of [2,3-(13)C(2),(15)N]-4-benzyloxy-5,6-diphenyl-2,3,5,6-tetrahydro-4H-oxazine-2-one via lipase TL-mediated kinetic resolution of benzoin: general procedure for the synthesis of [2,3-(13)C(2),(15)N]-L-alanine

Lipase TL-mediated kinetic resolution of benzoin proceeded to give the corresponding optically pure (R)-benzoin (R)-1. On the other hand, (S)-benzoin O-acetate (S)-7 could be hydrolyzed without epimerization to give (S)-benzoin (S)-1 under alkaline conditions. Furthermore, both enantiomers of benzoin (1) were converted to [(15)N]-(1R,2S)- and (1S,2R)- 2-amino-1,2-diphenylethanol (3a and 3b), respectively, according to the procedure reported previously. [2,3-(13)C(2),(15)N]-(5S,6R)-4-benzyloxy-5,6-diphenyl-2,3,5,6-tetrahydro-4H-oxazine-2-one (10) was synthesized from ethyl [1,2-(13)C(2)]bromoacetate and (1R,2S)-2-amino-1,2-diphenylethanol (3b) in three steps. Finally, [2,3-(13)C(2),(15)N]-L-alanine (12) was prepared via alkylation of the lactone 10 and hydrogenation of the alkylated product 11.

Taxol biosynthesis: taxane 13 alpha-hydroxylase is a cytochrome P450-dependent monooxygenase

A central feature in the biosynthesis of Taxol is oxygenation at multiple positions of the taxane core structure, reactions that are considered to be mediated by cytochrome P450-dependent monooxygenases. A PCR-based differential display-cloning approach, using Taxus (yew) cells induced for Taxol production, yielded a family of related cytochrome P450 genes, one of which was assigned as a taxane 10 beta-hydroxylase by functional expression in yeast. The acquired clones that did not function in yeast were heterologously expressed by using the Spodoptera fugiperda-baculovirus-based system and were screened for catalytic capability by using taxa-4(20),11(12)-dien-5 alpha-ol and its acetate ester as test substrates. This approach allowed identification of one of the cytochrome P450 clones (which bore 63% deduced sequence identity to the aforementioned taxane 10 beta-hydroxylase) as a taxane 13 alpha-hydroxylase by chromatographic and spectrometric characterization of the corresponding recombinant enzyme product. The demonstration of a second relevant hydroxylase from the induced family of cytochrome P450 genes validates this strategy for elucidating the oxygenation steps of taxane diterpenoid (taxoid) metabolism. Additionally, substrate specificity studies with the available cytochrome P450 hydroxylases now indicate that there is likely more than one biosynthetic route to Taxol in yew species.

Multiphoton microscopy in biological research

From its conception a decade ago, multiphoton microscopy has evolved from a photonic novelty to an indispensable tool for gleaning information from subcellular events within organized tissue environments. Its relatively deep optical penetration has recently been exploited for subcellularly resolved investigations of disease models in living transgenic mice. Its enhanced spectral accessibility enables aberration-free imaging of fluorescent molecules absorbing in deep-UV energy regimes with simultaneous imaging of species having extremely diverse emission spectra. Although excited fluorescence is the primary signal for multiphoton microscopy, harmonic generation by multiphoton scattering processes are also valuable for imaging species with large anharmonic modes, such as collagen structures and membrane potential sensing dyes.

Metabolic impact of puberty on the course of type 1 diabetes

Puberty is characterised by important physiological and hormonal changes. In type 1 diabetes, abnormalities in the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis play a important role. Spontaneous hyper-GH secretion arises, with reduced circulating IGF-1 levels, both leading to a reduction in insulin sensitivity. From a clinical point of view, these abnormalities are linked to a deterioration glycaemic control, often more marked in females (in whom the degree of insulin resistance during puberty seems to be higher). These abnormalities in the GH/IGF-1 axis in may constitute a risk for the development of microangiopathic complications. Optimisation of insulin therapy has practical limitations and intensification of insulin therapy poses problems (weight gain, nocturnal hypoglycaemia). Several alternative therapeutic approaches have been explored to restore insulin sensitivity, either through a direct effect on the GH/IGF-1 axis, or through drugs with a direct insulin sensitivity effect, but all these approaches remain to be confirmed and the safety and acceptability of these treatments to be established on a long-term basis.

Metallocyclodextrins as building blocks in noncovalent assemblies of photoactive units for the study of photoinduced intercomponent processes

Cyclodextrin cups have been employed to build supramolecular systems consisting of metal and organic photoactive/redox-active components; the photoinduced communication between redox-active units assembled in water via noncovalent interactions is established. The functionalization of a beta-cyclodextrin with a terpyridine unit, ttp-beta-CD, is achieved by protection of all but one of the hydroxyl groups by methylation and attachment of the ttp unit on the free primary hydroxyl group. The metalloreceptors [(beta-CD-ttp)Ru(ttp)][PF(6)](2), [(beta-CD-ttp)Ru(tpy)][PF(6)](2), and [Ru(beta-CD-ttp)(2)][PF(6)](2) are synthesized and fully characterized. The [(beta-CD-ttp)Ru(ttp)][PF(6)](2) metalloreceptor exhibits luminescence in water, centered at 640 nm, from the (3)MLCT state with a lifetime of 1.9 ns and a quantum yield of Phi = 4.1 x 10(-)(5). Addition of redox-active quinone guests AQS, AQC, and BQ to an aqueous solution of [(beta-CD-ttp)Ru(ttp)](2+) results in quenching of the luminescence up to 40%, 20%, and 25%, respectively. Measurement of the binding strength indicates that, in saturation conditions, 85% for AQS and 77% for AQC are bound. The luminescence quenching is attributed to an intercomponent electron transfer from the appended ruthenium center to the quinone guest inside the cavity. Control experiments demonstrate no bimolecular quenching at these conditions. A photoactive osmium metalloguest, [Os(biptpy)(tpy)][PF(6)], is designed with a biphenyl hydrophobic tail for insertion in the cyclodextrin cavity. The complex is luminescent at room temperature with an emission band maximum at 730 nm and a lifetime of 116 ns. The osmium(III) species are formed for the study of photoinduced electron transfer upon their assembly with the ruthenium cyclodextrin, [(beta-CD-ttp)Ru(ttp)](2+). Time-resolved spectroscopy studies show a short component of 10 ps, attributed to electron transfer from Ru(II) to Os(III) giving an electron transfer rate 9.5 x 10(9) s(-)(1).

The protein non-folding problem: amino acid determinants of intrinsic order and disorder

To investigate the determinants of protein order and disorder, three primary and one derivative database of intrinsically disordered proteins were compiled. The segments in each primary database were characterized by one of the following: X-ray crystallography, nuclear magnetic resonance (NMR), or circular dichroism (CD). The derivative database was based on homology. The three primary disordered databases have a combined total of 157 proteins or segments of length.30 with 18,010 residues, while the derivative database contains 572 proteins from 32 families with 52,688 putatively disordered residues. For the four disordered databases, the amino acid compositions were compared with those from a database of ordered structure. Relative to the ordered protein, the intrinsically disordered segments in all four databases were significantly depleted in W, C, F, I, Y, V, L and N, significantly enriched in A, R, G, Q, S, P, E and K, and inconsistently different in H, M, T, and D, suggesting that the first set be called order-promoting and the second set disorder-promoting. Also, 265 amino acid properties were ranked by their ability to discriminate order and disorder and then pruned to remove the most highly correlated pairs. The 10 highest-ranking properties after pruning consisted of 2 residue contact scales, 4 hydrophobicity scales, 3 scales associated with.-sheets and one polarity scale. Using these 10 properties for comparisons of the 3 primary databases suggests that disorder in all 3 databases is very similar, but with those characterized by NMR and CD being the most similar, those by CD and X-ray being next, and those by NMR and X-ray being the least similar.

Taxol biosynthesis: differential transformations of taxadien-5 alpha-ol and its acetate ester by cytochrome P450 hydroxylases from Taxus suspension cells

The biosynthesis of the diterpenoid antineoplastic drug Taxol in Taxus species involves the cyclization of the ubiquitous isoprenoid intermediate geranylgeranyl diphosphate to taxa-4(5),11(12)-diene followed by cytochrome P450-mediated hydroxylation (with allylic rearrangement) of this olefin precursor to taxa-4(20),11(12)-dien-5 alpha-ol, and further oxygenation and acylation reactions. Based on the abundances of naturally occurring taxoids, the subsequent order of oxygenation of the taxane core is considered to occur at C10, then C2 and C9, followed by C13, and finally C7 and C1. Circumstantial evidence suggests that the acetylation of taxadien-5 alpha-ol may constitute the third specific step of Taxol biosynthesis. To determine whether taxadienol or the corresponding acetate ester serves as the direct precursor of subsequent oxygenation reactions, microsomal preparations isolated from induced Taxus cells and optimized for cytochrome P450 catalysis were incubated with each potential substrate. Both taxadienol and taxadienyl acetate were oxygenated to the level of a diol and to higher polyols at comparable rates by cytochrome P450 enzymes of the microsomal preparation. Preparative-scale incubation allowed the isolation of sufficient quantities of the diol derived from taxadienol to permit the NMR-based structural elucidation of this metabolite as taxa-4(20),11(12)-dien-5 alpha,13 alpha-diol, which may represent an alternate route of taxoid metabolism in induced cells. GC-MS-based structural definition of the diol monoacetate derived in microsomes from taxadienyl acetate confirmed this metabolite as taxa-4(20),11(12)-dien-5 alpha-acetoxy-10 beta-ol, thereby indicating that acetylation at C5 of taxadienol precedes the cytochrome P450-mediated insertion of the C10-beta-hydroxyl group of Taxol.

Stereocontrolled asymmetric synthesis of alpha-hydroxy-beta-amino acids. A stereodivergent approach

The stereocontrolled asymmetric synthesis of alpha-hydroxy-beta-amino acids has been investigated via the Lewis acid-promoted cyanation of (5R,6S)-2-acetoxy-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazines with trimethylsilyl cyanide. Base-catalyzed hydrolysis of the resulting cyano compounds proceeds with excellent stereoselectivity, providing access to diastereomerically pure oxazine-2-carboxylic acids which were readily converted to each enantiomer of the alpha-hydroxy-beta-amino acids isothreonine and nor-C-statine.

Ancient geodynamics and global-scale hydrology on Mars

Loading of the lithosphere of Mars by the Tharsis rise explains much of the global shape and long-wavelength gravity field of the planet, including a ring of negative gravity anomalies and a topographic trough around Tharsis, as well as gravity anomaly and topographic highs centered in Arabia Terra and extending northward toward Utopia. The Tharsis-induced trough and antipodal high were largely in place by the end of the Noachian Epoch and exerted control on the location and orientation of valley networks. The release of carbon dioxide and water accompanying the emplacement of approximately 3 x 10(8) cubic kilometers of Tharsis magmas may have sustained a warmer climate than at present, enabling the formation of ancient valley networks and fluvial landscape denudation in and adjacent to the large-scale trough.

Genomic evidence for a complete sexual cycle in Candida albicans

Candida albicans is a diploid fungus that has become a medically important opportunistic pathogen in immunocompromised individuals. We have sequenced the C. albicans genome to 10.4-fold coverage and performed a comparative genomic analysis between C. albicans and Saccharomyces cerevisiae with the objective of assessing whether Candida possesses a genetic repertoire that could support a complete sexual cycle. Analyzing over 500 genes important for sexual differentiation in S. cerevisiae, we find many homologues of genes that are implicated in the initiation of meiosis, chromosome recombination, and the formation of synaptonemal complexes. However, others are striking in their absence. C. albicans seems to have homologues of all of the elements of a functional pheromone response pathway involved in mating in S. cerevisiae but lacks many homologues of S. cerevisiae genes for meiosis. Other meiotic gene homologues in organisms ranging from filamentous fungi to Drosophila melanogaster and Caenorhabditis elegans were also found in the C. albicans genome, suggesting potential alternative mechanisms of genetic exchange.

Molecular cloning of a cytochrome P450 taxane 10 beta-hydroxylase cDNA from Taxus and functional expression in yeast

The early steps in the biosynthesis of Taxol involve the cyclization of geranylgeranyl diphosphate to taxa-4(5),11(12)-diene followed by cytochrome P450-mediated hydroxylation at C5, acetylation of this intermediate, and a second cytochrome P450-dependent hydroxylation at C10 to yield taxadien-5 alpha-acetoxy-10 beta-ol. Subsequent steps of the pathway involve additional cytochrome P450 catalyzed oxygenations and CoA-dependent acylations. The limited feasibility of reverse genetic cloning of cytochrome P450 oxygenases led to the use of Taxus cell cultures induced for Taxol production and the development of an approach based on differential display of mRNA-reverse transcription-PCR, which ultimately provided full-length forms of 13 unique but closely related cytochrome P450 sequences. Functional expression of these enzymes in yeast was monitored by in situ spectrophotometry coupled to in vivo screening of oxygenase activity by feeding taxoid substrates. This strategy yielded a family of taxoid-metabolizing enzymes and revealed the taxane 10 beta-hydroxylase as a 1494-bp cDNA that encodes a 498-residue cytochrome P450 capable of transforming taxadienyl acetate to the 10 beta-hydroxy derivative; the identity of this latter pathway intermediate was confirmed by chromatographic and spectrometric means. The 10 beta-hydroxylase represents the initial cytochrome P450 gene of Taxol biosynthesis to be isolated by an approach that should provide access to the remaining oxygenases of the pathway.

Growth arrest of individual senile plaques in a model of Alzheimer's disease observed by in vivo multiphoton microscopy

In Alzheimer's disease, amyloid-beta peptide aggregates in the extracellular space to form senile plaques. The process of plaque deposition and growth has been modeled on the basis of in vitro experiments in ways that lead to divergent predictions: either a diffusion-limited growth model in which plaques grow by first-order kinetics, or a dynamic model of continual deposition and asymmetrical clearance in which plaques reach a stable size and stop growing but evolve morphologically over time. The models have not been tested in vivo because plaques are too small (by several orders of magnitude) for conventional imaging modalities. We now report in vivo multiphoton laser scanning imaging of thioflavine S-stained senile plaques in the Tg2576 transgenic mouse model of Alzheimer's disease to test these biophysical models and show that there is no detectable change in plaque size over extended periods of time. Qualitatively, geometric features remain unchanged over time in the vast majority of the 349 plaques imaged and re-imaged. Intervals as long as 5 months were obtained. Nonetheless, rare examples of growth or shrinkage of individual plaques do occur, and new plaques appear between imaging sessions. These results indicate that thioflavine S-positive plaques appear and then are stable, supporting a dynamic feedback model of plaque growth.

Arglabin-DMA, a plant derived sesquiterpene, inhibits farnesyltransferase

Arglabin [1(R),10(S)-epoxy-5(S),5(S),7(S)-guaia-3(4),11(13)-dien-6, 12-olide], a sesquiterpene gamma-lactone is isolated from Artemisia glabella, a species of wormwood endemic to the Karaganda region of Kazakstan. The compound has been modified to render it water-soluble through addition of a dimethylaminohydrochloride group to the C(13) carbohydride moiety to yield Arglabin-DMA. Arglabin-DMA is a registered antitumor substance in the Republic of Kazakstan. Previously, we have shown that this compound prevents protein farnesylation without altering geranylgeranylation. We now report that Arglabin-DMA inhibits the incorporation of [(3)H]farnesylpyrophosphate into human H-ras protein by FTase with an IC(50) of no greater than 25 microM. Kinetic studies show that the phosphorylated form of this compound competitively inhibits the binding of farnesyl diphosphate to FTase. This mechanism of action is different from other reported peptidomimetic FTIs which lower the affinity of ras protein to FTase. Our in vitro studies confirm that Arglabin-DMA inhibits post-translational modification of ras protein in cells. Arglabin-DMA inhibits anchorage-dependent proliferation of NB cells (IC50=10 microg/ml) and inhibits anchorage-independent growth of NB and KNRK cells with about the same IC(50). Soft-agar colony formation assay of H-ras and K-ras transformed cells show IC(50)s to be 2 and 5 microg/ml, respectively. In primary cultures of human tumor cells, Arglabin-DMA inhibits cell proliferation of a variety of tumor types with IC(90)s in the range of 0.85 to 5.0 microg/ml. Because of these pharmacologic properties, we propose that Arglabin-DMA is suitable for the treatment of ras related malignancies.

Decreased expression of Wnt7a mRNA is inversely associated with the expression of estrogen receptor-alpha in human uterine leiomyoma

Wnt-7a gene not only guides the development of the anterior-posterior axis in the female reproductive tract, but also plays a critical role in uterine smooth muscle pattering and maintenance of adult uterine function. This gene is also responsive to changes in the levels of sex steroid hormone in the female reproductive tract. To explore the molecular mechanisms underlying the pathogenesis of uterine leiomyoma, the expression of Wnt7a mRNA in the leiomyoma has been assessed. RT-PCR was performed on uterine leiomyomas and the adjacent myometria. Of 30 cases of leiomyomas studied, 67% showed a decreased mRNA level as compared to the paired myometria. On the other hand, estrogen receptor-alpha (ER-alpha) mRNA is hyper-expressed in 67% of the leiomyomas as compared to their paired myometrium. An inverse association at mRNA expression was found between Wnt7a and ER-alpha. Miller et alhas shown that fetal exposure of DES results in de-regulation of Wnt7a during uterine morphogenesis. Referring to their results, we have postulated that hypersensitivity of leiomyoma cells to estrogen may deregulate the Wnt7a expression. Decreased expression of Wnt7a may lead to loss of control in patterning of the myometrium and result in development of leiomyoma

Intramolecular proton transfer in the cyclization of geranylgeranyl diphosphate to the taxadiene precursor of taxol catalyzed by recombinant taxadiene synthase

BACKGROUND

The committed step in the biosynthesis of the anticancer drug taxol in yew (Taxus) species is the cyclization of geranylgeranyl diphosphate to taxa-4(5),11(12)-diene. The enzyme taxadiene synthase catalyzes this complex olefin cation cyclization cascade involving the formation of three rings and three stereogenic centers.

RESULTS

Recombinant taxadiene synthase was incubated with specifically deuterated substrates, and the mechanism of cyclization was probed using MS and NMR analyses of the products to define the crucial hydrogen migration and terminating deprotonation steps. The electrophilic cyclization involves the ionization of the diphosphate with closure of the A-ring, followed by a unique intramolecular transfer of the C11 proton to the re-face of C7 to promote closure of the B/C-ring juncture, and cascade termination by proton elimination from the beta-face of C5.

CONCLUSIONS

These findings provide insight into the molecular architecture of the first dedicated step of taxol biosynthesis that creates the taxane carbon skeleton, and they have broad implications for the general mechanistic capability of the large family of terpenoid cyclization enzymes.

The core meiotic transcriptome in budding yeasts

We used high-density oligonucleotide microarrays to analyse the genomes and meiotic expression patterns of two yeast strains, SK1 and W303, that display distinct kinetics and efficiencies of sporulation. Hybridization of genomic DNA to arrays revealed numerous gene deletions and polymorphisms in both backgrounds. The expression analysis yielded approximately 1,600 meiotically regulated genes in each strain, with a core set of approximately 60% displaying similar patterns in both strains. Most of these (95%) are MATa/MATalpha-dependent and are not similarly expressed in near-isogenic meiosis-deficient controls. The transcript profiles correlate with the distribution of defined meiotic promoter elements and with the time of known gene function.