Involvement of the amino-terminal phosphorylation module of UhpA in activation of uhpT transcription in Escherichia coli.

The UhpA protein is required for expression of the sugar phosphate transporter UhpT in Escherichia coli and is regulated by phosphate transfer from the transmembrane UhpBC sensor kinase complex. UhpA action requires the sensor kinase complex and the site of phosphorylation, Asp-54, under normal conditions, but not when UhpA is overexpressed. Directed mutagenesis of the uhpA gene allowed examination of the role of several residues of UhpA in response to phosphorylation and in transcription activation.

The feasibility of measuring bone uranium concentrations in vivo using source excited K x-ray fluorescence.

X-ray fluorescence (XRF) has been demonstrated to be an extremely useful technique for measuring trace quantities of heavy metals in various tissues within the body. This study investigates the applicability of XRF to the measurement of bone uranium concentration. The factors affecting the accuracy and minimal detectable concentration of bone uranium in vivo are discussed.

Immunity to cartilage link protein in patients with juvenile rheumatoid arthritis.

Objective: To determine whether children with juvenile rheumatoid arthritis (JRA) express cellular immunity to cartilage link protein.

Methods: Link protein was purified from human fetal epiphyseal and bovine adult nasal cartilage. It was used in proliferation assays with the peripheral blood lymphocytes isolated from 54 children with JRA and 22 nonarthritic controls.

In vivo assessment of trabecular bone structure at the distal radius from high-resolution magnetic resonance images.

In this study a method of assessing trabecular bone structure at the distal end of the radius from high-resolution magnetic resonance images is described. Trabecular bone is segmented from the marrow and soft tissue background using an adaptive threshold, a region growth, and a skeletonization step. From the processed image we measured the connectivity and orientation of the trabecular bone network.

Gymnastic training and bone density in pre-adolescent females.

Bone mineral density (BMD) was compared between 7-11-yr-old female gymnasts (GYM: N = 16) with a history of high volume impact loading (minimum of 15 h.wk-1 for past 2 yr) and healthy nonathletic controls (CON: N = 16). Whole body (WB) and regional areal BMD measures were determined by dual energy x-ray absorptiometry (DXA) normalized for height and body mass and also converted to bone mineral apparent density (BMAD).

Further experience with bone lead content measurements in residents of southern Ontario.

Bone lead content of the mid-tibia was measured by in vivo fluorescence excitation in 90 females and 59 males aged between 6 and 81. The cross-sectionally derived rate of increase of tibia lead content was 0.24 +/- 0.

Accumulated body burden and endogenous release of lead in employees of a lead smelter.

Bone lead levels for 367 active and 14 retired lead smelter workers were measured in vivo by X-ray fluorescence in May-June 1994. The bone sites of study were the tibia and calcaneus; magnitudes of concentration were used to gauge lead body burden. Whole blood lead readings from the workers generated a cumulative blood lead index (CBLI) that approximated the level of lead exposure over time.

Lumbar paraspinal muscle fatigability in repetitive isoinertial loading: EMG spectral indices, Borg scale and endurance time.

The purpose of this study was to develop a submaximal repetitive isoinertial back muscle endurance test by defining the relationships between the power spectral indices of paraspinal muscle electromyographic (EMG) activities, endurance time and a subjective estimate of fatigue (Borg scale). Bilateral surface EMG recordings were obtained over the lumbar paraspinal muscles in ten individuals who were currently free from back pain. All subjects performed repetitive upper trunk extensions (25 degrees flexion and 5 degrees extension, 30 repetitions per min), while movement below the third lumbar vertebral body was mechanically restricted.

Altered mineral metabolism and bone mass in children during treatment for acute lymphoblastic leukemia.

Children with acute lymphoblastic leukemia (ALL) often develop bone pain, abnormal gait, and unusual fractures while in remission and receiving continuing chemotherapy. A prospective longitudinal cohort study was undertaken of bone mass and biochemical mineral status in 40 consecutive children (27 male, 13 female, aged 0.3-17.

A longitudinal trial of weight training in the elderly: continued improvements in year 2.

We conducted a 2-year (42 weeks of consecutive training in each year, separated by 10 weeks of testing and vacation time) randomized, controlled trial of weight training in 142 healthy male and female subjects, aged 60 to 80 years. Measurements included dynamic strength, symptom-limited endurance in cycling, treadmill walking and stair climbing, muscle size, and bone mineral density and content of the lumbar spine and whole body. One hundred and thirteen subjects completed the study (57 exercise, 56 control), with a mean attendance of 85% among the exercisers.

Twenty weeks of weight training increases lean tissue mass but not bone mineral mass or density in healthy, active young women.

Twenty young women (20.3 +/- 1.0 years) participated in a weight training program in which upper and lower body exercises were done twice per week for 20 weeks.

Effects of resistance training on bone mineral content and density in adolescent females.

Postmenarcheal adolescent girls performed resistance training (RT) for 26 weeks, which consisted of 4 sets of 13 exercises of varying and progressive intensity performed 3 times weekly on hydraulic resistance machines. Bone mineral was assessed by dual photon absorptiometry. Resistance training resulted in significant increases (pre-post) in biceps curl (21.

Postmenopausal bone mineral density: relationship to calcium intake, calcium absorption, residual estrogen, body composition, and physical activity.

Physical and lifestyle data were collected from 62 postmenopausal women who had declined hormone replacement therapy. Potential predictor variables were examined for their associations with bone mineral density (BMD) of the lumbar spine and femoral neck as assessed by dual x-ray absorptiometry. Body weight demonstrated the strongest association with lumbar BMD; lean body mass demonstrated the strongest association with femoral BMD.

Vitamin D and calcium in the prevention of corticosteroid induced osteoporosis: a 3 year followup.

Objective: To determine the efficacy and safety of vitamin D 50,000 units/week and calcium 1,000 mg/day in the prevention of corticosteroid induced osteoporosis.

Methods: A minimized double blind, placebo controlled trial in corticosteroid treated subjects in a tertiary care university affiliated hospital. The sample was 62 subjects with polymyalgia rheumatica, temporal arteritis, asthma, vasculitis, or systemic lupus erythematosus.

Fluoride supplementation status, fractures and osteopenia in children with acute lymphoblastic leukemia.

Children with acute lymphoblastic leukemia (ALL) experience fractures on the basis of osteopenia related to chemotherapy administered for the maintenance of remission. It is likely that corticosteroids are the main cause of bone mineral loss in this circumstance. Because fluoride has been used as a therapeutic intervention in osteoporosis, including that induced by corticosteroid therapy, we explored the prospect that children with ALL who received fluoride supplementation (in drinking water or from other sources) may be relatively protected from iatrogenic skeletal morbidity.

Partition of circulating lead between serum and red cells is different for internal and external sources of lead.

Serum lead, whole blood lead, and lead in both tibia and calcaneus were measured in each of 49 active lead workers. Serum lead correlated more strongly with both in vivo bone lead measurements than did whole blood lead. The ratio of serum lead to whole blood lead varied from 0.

In vivo assessment of trabecular bone structure at the distal radius from high-resolution computed tomography images.

A dedicated computed tomography system was used to acquire transaxial images of the distal radius to assess trabecular bone structure in vivo. We segmented trabecular bone from the marrow and soft tissue background by postprocessing the image with a region grow and skeletonization step. From the processed image we assessed the integrity of the bone by examining the continuity of its trabecular network and by determining the area of the holes comprising its marrow space.

The effects of long-term heparin therapy during pregnancy on bone density. A prospective matched cohort study.

We performed a prospective matched cohort study to investigate the effects of long-term (> 1 month) heparin therapy on lumbar spine bone density. Twenty-five women who received heparin during pregnancy, and 25 matched controls underwent dual photon absorptiometry of the lumbar spine in the post-partum period. Zero of 25 heparin-treated patients developed fractures.

A Markovian formalization of heart rate dynamics evinces a quantum-like hypothesis.

Most investigations into heart rate dynamics have emphasized continuous functions, whereas the heart beat itself is a discrete event. We present experimental evidence that by considering this quality, the dynamics may be appreciated as a result of singular dynamics arising out of non-Lipschitz formalisms. Markov process analysis demonstrates that heart beats may then be considered in terms of quantum-like constraints.

Immunity to the G1 globular domain of the cartilage proteoglycan aggrecan can induce inflammatory erosive polyarthritis and spondylitis in BALB/c mice but immunity to G1 is inhibited by covalently bound keratan sulfate in vitro and in vivo.

Earlier work from this laboratory showed that the human proteoglycan aggrecan from fetal cartilages can induce a CD4+ T cell-dependent inflammatory polyarthritis in BALB/c mice when injected after removal of chondroitin sulfate chains. Adult keratan sulfate (KS)-rich aggrecan does not possess this property. We found that two CD4+ T cell hybridomas (TH5 and TH14) isolated from arthritic mice recognize bovine calf aggrecan and the purified G1 domain of this molecule, which also contains a portion of the interglobular domain to which KS is bound.

Hormone replacement therapy may reduce the return of endogenous lead from bone to the circulation.

Hormone replacement therapy (HRT) in postmenopausal women suppresses the increase in bone resorption expected as circulating levels of endogenous estrogen decline. We tested the hypothesis that bone lead content might remain elevated in women on HRT. Fifty six women who at recruitment were on average 35 years postmenopausal were placed on calcium supplementation.

Mineral homeostasis and bone mass at diagnosis in children with acute lymphoblastic leukemia.

Objective: To determine whether the osteopenia and unusual fractures observed in children with acute lymphoblastic leukemia (ALL) were related to the disease rather than to its treatment.

Design: Prospective analysis of the bone and mineral status in 40 consecutive children with ALL seen in a pediatric tertiary-care referral center.

Methods: Biochemical indicators of mineral, endocrine, and vitamin D status were measured before initiation of therapy.

Long-term resistance training in the elderly: effects on dynamic strength, exercise capacity, muscle, and bone.

We examined the effects of 42 weeks of progressive weight-lifting training on dynamic muscle strength, peak power output in cycle ergometry, symptom limited endurance during progressive treadmill walking and stair climbing, knee extensor cross-sectional areas, and bone mineral density and content in healthy males and females aged 60-80 years, currently enrolled in a 2-year resistance training program. Subjects were randomized into either exercise (EX) or control (CON) groups (60-70 years: 38 males and 36 females; 70-80 years: 25 males and 43 females). EX trained several muscle groups twice per week for 42 weeks at intensities ranging from 50-80% of the load that they could lift once only (1 RM); CON did usual daily activities.

Influence of isometric loading on biceps EMG dynamics as assessed by linear and nonlinear tools.

The summed electrical discharges generated by a contracting skeletal muscle constitute a dynamic system conveying electromyographic (EMG) information indicative of muscle physiological status. "Steady states" of activity can be achieved with light loads, but with heavy loads the dynamic system experiences continuous status transitions that culminate in task failure. The present study was designed to assess the applicability of two mathematical tools, one linear and the other nonlinear, in addressing the time course of EMG alterations under different loading challenges.