Search PubMed⌕ Search

Biomedical subjects

V Robinson

Publications and source records attributed to V Robinson.

At least 37 records · Page 2Linked to original sources
PubMed2003

Calcium supplementation on bone loss in postmenopausal women.

BACKGROUND: Although calcium is one the simplest and least expensive strategies for preventing osteoporotic fractures calcium supplementation is nevertheless not without controversy (Kanis 1989; Nordin 1990). The Food and Drug Administration in the US has permitted a bone health claim for calcium-rich foods, and the NIH in its Consensus Development Process approved a statement that high calcium intake reduces the risk of osteoporosis. OBJECTIVES: To assess the effects of calcium on bone density and fractures in postmenopausal women. SEARCH STRATEGY: We searched Cochrane Controlled Register, MEDLINE and EMBASE up to 2001, and examined citations of relevant articles and proceedings of international meetings. SELECTION CRITERIA: Trials that randomized postmenopausal women to calcium supplementation or usual calcium intake in the diet and reported bone mineral density of the total body, vertebral spine, hip, or forearm or recorded the number of fractures, and followed patients for at least one year were considered for inclusion. DATA COLLECTION AND ANALYSIS: Three independent reviewers assessed the methodologic quality and extracted data for each trial. For each bone density site (lumbar spine, total body, combined hip and combined forearm), we calculated the weighted mean difference in bone density between treatment and control groups using the percentage change from baseline. We constructed regression models in which the independent variables were year and dose, and the dependent variable was the effect size. This regression was used to determine the years across which pooling was appropriate. Heterogeneity was assessed. For each fracture analysis we calculated a risk ratio. MAIN RESULTS: Fifteen trials, representing 1806 participants, were included. Calcium was more effective than placebo in reducing rates of bone loss after two or more years of treatment. The pooled difference in percentage change from baseline was 2.05% (95% CI 0.24 to 3.86) for total body bone density, 1.66% (95% CI 0.92 to 2.39) for the lumbar spine at 2 years, 1.60% (95% CI 0.78 to 2.41) for the hip, and 1.91% (95% CI 0.33 to 3.50) for the distal radius. The relative risk of fractures of the vertebrae was 0.79 (95% CI 0.54 to 1.09); the relative risk for non-vertebral fractures was 0.86 (95% CI 0.43 to 1.72). REVIEWER'S CONCLUSIONS: Calcium supplementation alone has a small positive effect on bone density. The data show a trend toward reduction in vertebral fractures, but it is unclear if calcium reduces the incidence of non vertebral fractures.

Bone Density↗
PubMed2003

Number needed to treat (NNT): implication in rheumatology clinical practice.

OBJECTIVE: To calculate the number needed to treat (NNT) and number needed to harm (NNH) from the data in rheumatology clinical trials and systematic reviews. METHODS: The NNTs for the clinically important outcome measures in the rheumatology systematic reviews from the Cochrane Library, issue 2, 2000 and in the original randomised, double blind, controlled trials were calculated. The measure used for calculating the NNT in rheumatoid arthritis (RA) interventions was the American College of Rheumatology 20% improvement or Paulus criteria; in osteoarthritis (OA) interventions, the improvement of pain; and in systemic sclerosis (SSc) interventions, the improvement of Raynaud's phenomenon. The NNH was calculated from the rate of withdrawals due to adverse events from the treatment. RESULTS: The data required for the calculation of the NNT were available in 15 systematic reviews and 11 original articles. For RA interventions, etanercept treatment for six months had the smallest NNT (1.6; 95% confidence interval (CI) 1.4 to 2.0), whereas leflunomide had the largest NNH (9.6; 95% CI 6.8 to 16.7). For OA treatment options, only etodolac and tenoxicam produced significant pain relief compared with placebo (NNT=4.4; 95% CI 2.4 to 24.4 and 3.8; 95% CI 2.5 to 7.3, respectively). For SSc interventions, none were shown to be efficacious in improving Raynaud's phenomenon because the 95% CI of the NNT was infinite. CONCLUSIONS: The NNT and NNH are helpful for clinicians, enabling them to translate the results from clinical trials and systematic reviews to use in routine clinical practice. Both NNT and NNH should be accompanied by a limited 95% CI and adjusted for the individual subject's baseline risk.

Antirheumatic Agents↗
PubMed2002

Exercise for preventing and treating osteoporosis in postmenopausal women.

BACKGROUND: Osteoporosis is a condition resulting in an increased risk of skeletal fractures due to a reduction in the density of bone tissue. Prevention of osteoporotic-related fractures is dependent on the ability to detect individuals with low bone mass, including those women who are asymptomatic. Treatment of osteoporosis involves the use of either anti-resorptive (e.g. estrogen and bisphosphonate) or bone formation agents (e.g. fluoride and PTH). The value of exercise as an intervention for the prevention of postmenopausal bone loss is a controversial subject. OBJECTIVES: To examine the effectiveness of exercise therapy at preventing bone loss and fractures in postmenopausal women. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Group's specialised register, MEDLINE, EMBASE, Current Contents and the Cochrane Controlled Trials Registry up to January 2000 according to the methods suggested by Dickersin et al and Haynes et al and the Cochrane Handbook. We hand searched reference lists and consulted content experts. SELECTION CRITERIA: This review was proceeded by a peer reviewed protocol published in the Cochrane Library. Two reviewers independently selected all randomized controlled trials (RCTs) which met our predetermined inclusion criteria. DATA COLLECTION AND ANALYSIS: The same two reviewers abstracted the data using predetermined forms and assessed trial quality using a validated assessment tool. For dichotomous outcomes (fractures), relative risks were calculated using fixed effects models. For continuous data, weighted mean differences (WMD) of the percentage change from baseline were calculated. Where heterogeneity existed (determined by a chi square test), a random effects model was used. MAIN RESULTS: Eighteen randomized controlled trials (RCTs) met the inclusion criteria. The trials had a mean methodological quality score of 2.53. Aerobics, weight bearing and resistance exercises were all effective on the BMD of the spine. The WMD for the combined aerobics and weight bearing program on the spine was 1.79 [95%CI (0.58, 3.01)]. The analyzed results showed walking to be effective on both BMD of the spine 1.31[95%CI (-0.03, 2.65) and the hip 0.92[95%CI (0.21, 1.64). Aerobic exercise was effective in increasing BMD of the wrist 1.22[95%CI (0.71, 1.74)]. REVIEWER'S CONCLUSIONS: Aerobics, weight bearing and resistance exercises are all effective in increasing the BMD of the spine in postmenopausal women. Walking is also effective on the hip. The quality of the reporting of the trials in the meta-analysis was low, in particular, in the areas of allocation concealement and blinding.

Exercise↗
PubMed2002

Electromagnetic fields for the treatment of osteoarthritis.

BACKGROUND: As the focus for osteoarthritis (OA) treatment shifts away from drug therapy, we consider the effectiveness of pulsed electric stimulation which is proven to stimulate cartilage growth on the cellular level. OBJECTIVES: 1)To assess the effectiveness of pulsed electric stimulation for the treatment of osteoarthritis (OA). 2) To assess the most effective and efficient method of applying an electromagnetic field, through pulsed electromagnetic fields (PEMF) or electric stimulation, as well as the consideration of length of treatment, dosage, and the frequency of the applications. SEARCH STRATEGY: We searched PREMEDLINE, MEDLINE, HealthSTAR, CINAHL, PEDro, and the Cochrane Controlled Trials Register (CCTR) up to and including 2001. This included searches through the coordinating offices of the trials registries of the Cochrane Field of Physical and Related Therapies and the Cochrane Musculoskeletal Group for further published and unpublished articles. The electronic search was complemented by hand searches and experts in the area. SELECTION CRITERIA: Randomized controlled trials and controlled clinical trials that compared PEMF or direct electric stimulation against placebo in patients with OA. DATA COLLECTION AND ANALYSIS: Two reviewers determined the studies to be included in the review based on inclusion and exclusion criteria (JH,VR) and extracted the data using pre-developed extraction forms for the Cochrane Musculoskeletal Group. The methodological quality of the trials was assessed by the same reviewers using a validated scale (Jadad 1996). Osteoarthritis outcome measures were extracted from the publications according to OMERACT guidelines (Bellamy 1997) and additional secondary outcomes considered. MAIN RESULTS: Only three studies with a total of 259 OA patients were included in the review. Electrical stimulation therapy had a small to moderate effect on outcomes for knee OA, all statistically significant with clinical benefit ranging from 13-23% greater with active treatment than with placebo. Only 2 outcomes for cervical OA were significantly different with PEMF treatment and no clinical benefit can be reported with changes of 12% or less. REVIEWER'S CONCLUSIONS: Current evidence suggests that electrical stimulation therapy may provide significant improvements for knee OA, but further studies are required to confirm whether the statistically significant results shown in these trials confer to important benefits.

Clinical Trials as Topic↗
PubMed2002

Deep transverse friction massage for treating tendinitis.

BACKGROUND: Deep transverse friction massage (DTFM) is one of several physiotherapy interventions suggested for the management of pain due to iliotibial band friction syndrome (ITBFS). OBJECTIVES: To assess the effectiveness of DTFM for treating ITBFS observed in runners. SEARCH STRATEGY: We searched the Medline, Embase, Healthstar, Sports Discus, CINAHL, the Cochrane Controlled Trials Register, PEDro, the specialized registry of the Cochrane musculoskeletal group and the Cochrane field of Physical and Related Therapies up to the end of December 2000, using the sensitive search strategy developed by the Cochrane Collaboration. The search was complemented with bibliography searching of the reference list of the trials retrieved from the electronic search. Key experts in the area were contacted for further published and unpublished articles. SELECTION CRITERIA: All randomized controlled trials (RCTs) and controlled clinical trials (CCTs) comparing therapeutic ultrasound against placebo or another active intervention in patients with patellofemoral pain syndrome were selected. DATA COLLECTION AND ANALYSIS: Two reviewers determined the studies to be included based on inclusion and exclusion criteria (LB, VR). Data were independently abstracted by two reviewers (VR, LB), and checked by a third reviewer (BS) using a pre-developed form of the Cochrane Musculoskeletal Group. The same two reviewers, using a validated scale, assessed the methodological quality of the RCTs and CCTs independently. Iliotibial band friction syndrome outcome measures were extracted from the publications. The pooled analysis was performed using weighted mean differences (WMDs) for pain relief as described as 1) daily pain; 2) pain while running and 3) percentage of maximum pain when running. A chi-square test was used to assess heterogeneity among trials. Fixed effects models were used throughout and random effects for outcomes showing heterogeneity. MAIN RESULTS: One RCT, including 17 patients with ITBFS was included. The experimental group (DTFM combined to rest, stretching exercises, cryotherapy and therapeutic ultrasound) (n=9) was compared to the control group (rest, stretching exercises, cryotherapy and therapeutic ultrasound only) (n=8). This trial showed no statistical difference in the three types of pain relief measured after four consecutive sessions of DTFM combined with other physiotherapy modalities for runners. Despite lack of statistical significance, there was a clinically important relative percentage difference in pain while running of 22%. REVIEWER'S CONCLUSIONS: DTFM combined with other physiotherapy modalities did not show consistent benefit over control of pain for runners experiencing ITBFS. These conclusions are limited by the low methodological quality of the one small sample size trial (n=17) included. No conclusions can be drawn about the use or non use of DTFM for the treatment of ITBFS. Future trials, utilizing appropriate methods and adequate sample sizes are needed before conclusions can be drawn regarding the effect of massage on iliotibial band friction syndrome.

Clinical Trials as Topic↗
PubMed2002

Therapeutic ultrasound for the treatment of rheumatoid arthritis.

BACKGROUND: Ultrasound is often used, by rehabilitation specialists, as an adjunct therapy for the symptomatic treatment of rheumatoid arthritis (RA). Its mechanical energy has antiinflammatory as well as analgesic properties. OBJECTIVES: To evaluate the effects of ultrasound on objective and subjective measures of disease activity in patients with RA. SEARCH STRATEGY: A comprehensive search was conducted up to September 2001 with MEDLINE, EMBASE, PEDro, Current Contents, Sports Discus and CINAHL. The Cochrane Field of Rehabilitation and Related Therapies and the Cochrane Musculoskeletal Review Group specialized registers were also searched. Handsearching was conducted on all retrieved papers and content experts were contacted to identify additional studies. SELECTION CRITERIA: Comparative controlled studies, such as randomized controlled trials and clinical controlled trials in patients with RA were eligible. No language restrictions were applied. Abstracts were accepted. DATA COLLECTION AND ANALYSIS: Two independent reviewers identified potential articles from the literature search. These reviewers extracted data using pre-defined extraction forms. Consensus was reached on all the extracted data. Quality was assessed by two reviewers using a 5 point validated assessment tool that measures the quality of randomization, double-blinding and description of withdrawals. MAIN RESULTS: Two studies (n=80 participants) met the inclusion criteria. Ultrasound to the palmar and dorsal aspect of the hand significantly increases grip strength when compared to a control (weighted mean difference (WMD) 28.07, 95CI: 13.37 to 42.77). Ultrasound to the palmar and dorsal aspects of the hand also appears to have beneficial effects to the following outcome measures: wrist dorsal flexion (WMD 1.90, 95%CI: 0.64 to 3.16), duration of morning stiffness (WMD 28.54, 95%CI: 0.18 to 56.90), number of swollen joints (WMD 1.02, 95%CI: 0.45 to 1.59) and the number of painful joints (WMD 1.20, 95%CI: 0.45 to 1.95). There is no significant difference between a)exercises and wax, b)exercises with ultrasound, c)exercises with ultrasound and faradic hand baths for the following outcome measures: pain score, grip strength, circumference of proximal interphalangeal (PIP) joints, articular index, range of motion or level of activity. REVIEWER'S CONCLUSIONS: The reviewers concluded that ultrasound in combination with the following treatment modalities; exercises, faradic current and wax baths, is not supported and cannot be recommended. Ultrasound alone can however, be used on the hand to increase grip strength, and to a lesser extent, based on the borderline results, increase wrist dorsal flexion, decrease morning stiffness, reduce the number of swollen joints and reduce the number of painful joints. It is important to note that these conclusions are limited by the methodological considerations such as poor quality of the trials, the low number of clinical trials, and the small sample size of the included studies.

Arthritis, Rheumatoid↗
PubMed2002

Acupuncture and electroacupuncture for the treatment of RA.

BACKGROUND: Acupuncture has been used by rehabilitation specialists as an adjunct therapy for the symptomatic treatment of rheumatoid arthritis (RA). Acupuncture is a traditional Chinese medicine where thin needles are inserted in specific documented points believed to represent concentration of body energies. In some cases a small electrical impulse is added to the needles. Once the needles are inserted in some of the appropriate points, endorphins, morphine-like substances, have been shown to be released in the patient's system, thus inducing local or generalised analgesia. OBJECTIVES: To evaluate the effects of acupuncture or electroacupuncture on the objective and subjective measures of disease activity in patients with RA. SEARCH STRATEGY: A comprehensive search was done up to September 2001 with MEDLINE, EMBASE, PEDro, Current Contents, Sports Discus and CINAHL. The Cochrane Field of Rehabilitation and Related Therapies and the Cochrane Musculoskeletal Review Group were also contacted for a search of their specialized registers. Handsearching was conducted on all retrieved papers and content experts were contacted to identify additional studies. SELECTION CRITERIA: Comparative controlled studies, such as randomized controlled trials and control clinical trials in patients with RA were eligible. No language restrictions were applied. Abstracts were accepted. DATA COLLECTION AND ANALYSIS: Two independent reviewers identified potential articles from the literature search. These reviewers extracted data using pre-defined extraction forms. Consensus was reached on all the extracted data. Quality was assessed by two reviewers using a five (5) point validated tool that measured the quality of randomization, double-blinding and description of withdrawals. MAIN RESULTS: Two studies (n=84) met the inclusion criteria. One used acupuncture (~~David 1999~~) while the other used electroacupuncture (~~Man 1974~~). In the first study using acupuncture, no significant difference was found between groups for to erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), the visual analogue scale for pain (VAS P), the visual analogue scale for patient's global assessment (VAS G), the number of swollen joints, the number of tender joints, to the general health questionnaire (GHQ), the score on the modified disease activity scale (DAS) or in the decrease in analgesic intake. In the second study, using electroacupuncture, a significant decrease in knee pain was reported in the experimental group, 24 hours post treatment, when compared to the placebo group (weighted mean difference of -2.0 with 95% CI -3.6,-4.0). REVIEWER'S CONCLUSIONS: Although the results of the ~~Man 1974~~ study show that electroacupuncture may be beneficial to reduce symptomatic knee pain in patients with RA 24 hours post treatment, the reviewers concluded that the poor quality of the trial, including the small sample size proclude its recommendation. The reviewers further conclude that acupuncture has no effect on ESR, CRP, pain, patient's global assessment, number of swollen joints, number of tender joints, general health, disease activity and reduction of analgesics. These conclusions are limited by methodological considerations such as the type of acupuncture (acupuncture vs electroacupuncture), the site of intervention, the low number of clinical trials and the small sample size of the included studies.

Acupuncture Therapy↗
PubMed2001

Elucidation of solvent exposure, side-chain reactivity, and steric demands of the trifluoromethionine residue in a recombinant protein.

When incorporated into proteins, fluorinated amino acids have been utilized as 19F NMR probes of protein structure and protein-ligand interactions, and as subtle structural replacements for their parent amino acids which is not possible using the standard 20-amino acid repertoire. Recent investigations have shown the ability of various fluorinated methionines, such as difluoromethionine (DFM) and trifluoromethionine (TFM), to be bioincorporated into recombinant proteins and to be extremely useful as 19F NMR biophysical probes. Interestingly, in the case of the bacteriophage lambda lysozyme (LaL) which contains only three Met residues (at positions 1, 14, and 107), four 19F NMR resonances are observed when TFM is incorporated into LaL. To elucidate the underlying structural reasons for this anomalous observation and to more fully explore the effect of TFM on protein structure, site-directed mutagenesis was used to assign each 19F NMR resonance. Incorporation of TFM into the M14L mutant resulted in the collapse of the two 19F resonances associated with TFM at position 107 into a single resonance, suggesting that when position 14 in wild-type protein contains TFM, a subtle but different environment exists for the methionine at position 107. In addition, 19F and [1H-13C]-HMQC NMR experiments have been utilized with paramagnetic line broadening and K2PtCl4 reactivity experiments to obtain information about the probable spatial position of each Met in the protein. These results are compared with the recently determined crystal structure of LaL and allow for a more detailed structural explanation for the effect of fluorination on protein structure.

Bacteriophage lambda↗
PubMed2001

Therapeutic ultrasound for treating patellofemoral pain syndrome.

BACKGROUND: Therapeutic ultrasound is one of several rehabilitation interventions suggested for the management of pain due to patellofemoral pain syndrome. OBJECTIVES: To assess the effectiveness and side effects of ultrasound therapy for treating patellofemoral pain syndrome. SEARCH STRATEGY: We searched MEDLINE, Embase, Healthstar, Sports Discus, CINAHL, the Cochrane Controlled Trials Register, the PEDro database, the specialized registry of the Cochrane musculoskeletal group and the Cochrane field of physical and related therapies up to December 2000 according to the sensitive search strategy for RCTs designed for the Cochrane Collaboration. The search was complemented with handsearching of the reference lists. Key experts in the area were contacted for further articles. SELECTION CRITERIA: All randomized controlled trials (RCTs) and controlled clinical trials (CCTs), case-control and cohort studies comparing therapeutic ultrasound against placebo or another active intervention in patients with patellofemoral pain syndrome were selected, according to an a priori protocol. DATA COLLECTION AND ANALYSIS: Two reviewers determined the studies to be included based on a priori inclusion criteria (LB, VAR). Data were independently abstracted by the same two reviewers, and checked by a third reviewer (BS) using a pre-developed form. The same two reviewers, using a validated scale, independently assessed the methodological quality of the RCTs and CCTs. The data analysis was performed using Peto Odds ratios. MAIN RESULTS: The search retrieved 85 articles. Of the 8 that were potentially relevant, only one RCT, including 53 patients with patellofemoral pain syndrome, was included. All patients received exercises as a concurrent therapy. Ultrasound combined with ice massage contrast (n=13) was not statistically different from ice massage alone (n=16) in terms of patient-rated pain relief improvement, quadriceps and hamstring strength. In the ultrasound and ice massage group, 46% (6/13) reported improved pain relief compared to 31% (4/13) in the ice massage alone group. This difference of 15% does not meet international standards for clinically important improvement in osteoarthritis of 20%. Side effects were not reported. REVIEWER'S CONCLUSIONS: Ultrasound therapy was not shown to have a clinically important effect on pain relief for patients with patellofemoral pain syndrome. These conclusions are limited by the poor reporting of the therapeutic application of the ultrasound and low methodological quality of the trial included. No conclusions can be drawn concerning the use or non use of ultrasound for treating patellofemoral pain syndrome. More well-designed studies are needed.

Humans↗
PubMed2001

Screening from a subtracted embryonic chick hindbrain cDNA library: identification of genes expressed during hindbrain, midbrain and cranial neural crest development.

The vertebrate hindbrain is segmented into a series of transient structures called rhombomeres. Despite knowing several factors that are responsible for the segmentation and maintenance of the rhombomeres, there are still large gaps in understanding the genetic pathways that govern their development. To find previously unknown genes that are expressed within the embryonic hindbrain, a subtracted chick hindbrain cDNA library has been made and 445 randomly picked clones from this library have been analysed using whole mount in situ hybridisation. Thirty-six of these clones (8%) display restricted expression patterns within the hindbrain, midbrain or cranial neural crest and of these, twenty-two are novel and eleven encode peptides that correspond to or are highly related to proteins with previously uncharacterised roles during early neural development. The large proportion of genes with restricted expression patterns and previously unknown functions in the embryonic brain identified during this screen provides insights into the different types of molecules that have spatially regulated expression patterns in cranial neural tissue.

Amino Acid Sequence↗
PubMed2001

Reactivity of free radicals on hydroxylated quartz surface and its implications for pathogenicity experimental and quantum mechanical study.

We studied the adsorption of hydroxyl radicals and superoxide anion radicals on a hydroxylated alpha-quartz surface using cluster and periodic slab models by means of density functional calculations. Models of two hydroxylated alpha-quartz surfaces--(0001) and (0111)--have been used in the simulations. The hydroxyl radical adsorbs readily on both surfaces. The subsurface Si-O bonds are weakened during the adsorption resulting in surface layer destabilization. This destabilization leads directly to surface disintegration in the case of *OH/(0111) adsorption. The product of the surface disintegration and reconstruction is a surface terminated by silanol groups (Si-OH) and siloxyl radicals (Si-O*). The model calculations suggest that adsorption of *OH on a hydroxylated quartz surface transforms a chemically inert, aged, silanol terminated surface to a very reactive, silicon-based radical terminated surface. The activated surface may then cause oxidative damage to the adsorbed biomaterial. The superoxide anion radical adsorbs on both surfaces, but the adsorption products are only weakly bonded to the surface. The calculated energy barrier for the O2*- activated subsurface Si-O bond dissociation is 10 kcal/mol, which is higher than for the *OH activated process (4 kcal/mol). The calculated weaker bonding to the surface and higher activation energy barrier suggest that the superoxide anion radical will be less efficient in reactivation of an aged, hydroxylated quartz surface than the hydroxyl radical. The importance of the specific geometry of the surface silicon atoms on the surface reactivity and adsorption properties is also discussed. The theoretical predictions are supported experimentally using chemiluminescence to monitor reactivation of the aged silica surface by superoxide anion radicals.

Adsorption↗
PubMed2000

Thermotherapy for treating rheumatoid arthritis.

BACKGROUND: Heat and cold therapy are often used as adjuncts in the treatment of rheumatoid arthritis by rehabilitation specialists. OBJECTIVES: To evaluate the effects of heat and cold on objective and subjective measures of disease activity in patients with rheumatoid arthritis. SEARCH STRATEGY: We searched Medline, Embase, PEDro, Current Contents, Sports Discus and CINAHL up to June 2000. The Cochrane Field of Rehabilitation and related therapies and the Cochrane Musculoskeletal Review Group were also contacted for a search of their specialized registers. Handsearching was conducted on all retrieved articles for additional articles. SELECTION CRITERIA: Randomized or controlled clinical trials of ice or heat compared to placebo or active interventions in patients with rheumatoid arthritis and case-control and cohort studies were eligible. No language restrictions were applied. Abstracts were accepted. DATA COLLECTION AND ANALYSIS: Two independent reviewers identified potential articles from the literature search. These reviewers extracted data using pre-defined extraction forms. Consensus was reached on all data extraction. Quality was assessed by two reviewers using a 5 point scale that measured the quality of randomization, double-blinding and description of withdrawals. MAIN RESULTS: Three studies (79 subjects) met the inclusion criteria. There was no effect on objective measures of disease activity (including inflammation, pain and x-ray measured joint destruction) of either ice versus control or heat versus control. Patients reported that they preferred heat therapy to no therapy (94% like heat therapy better than no therapy). There was no difference in patient preference for heat or ice. No harmful effects of ice or heat were reported. REVIEWER'S CONCLUSIONS: Since patients enjoy thermotherapy, and there are no harmful effects, thermotherapy should be recommended as a therapy which can be applied at home as needed to relieve pain. There is no need for further research on the effects of heat or cold for RA.

Arthritis, Rheumatoid↗
PubMed1999

In vivo cell sorting in complementary segmental domains mediated by Eph receptors and ephrins.

The restriction of intermingling between specific cell populations is crucial for the maintenance of organized patterns during development. A striking example is the restriction of cell mixing between segments in the insect epidermis and the vertebrate hindbrain that may enable each segment to maintain a distinct identity. In the hindbrain, this is a result of different adhesive properties of odd- and even-numbered segments (rhombomeres), but an adhesion molecule with alternating segmental expression has not been found. However, blocking experiments suggest that Eph-receptor tyrosine kinases may be required for the segmental restriction of cells. Eph receptors and their membrane-bound ligands, ephrins, are expressed in complementary rhombomeres and, by analogy with their roles in axon pathfinding, could mediate cell repulsion at boundaries. Remarkably, transmembrane ephrins can themselves transduce signals, raising the possibility that bi-directional signalling occurs between adjacent ephrin- and Eph-receptor-expressing cells. We report here that mosaic activation of Eph receptors leads to sorting of cells to boundaries in odd-numbered rhombomeres, whereas mosaic activation of ephrins results in sorting to boundaries in even-numbered rhombomeres. These data implicate Eph receptors and ephrins in the segmental restriction of cell intermingling.

Animals↗
PubMed1999

Comparative analysis of embryonic gene expression defines potential interaction sites for Xenopus EphB4 receptors with ephrin-B ligands.

The Eph family of receptor tyrosine kinases and their ligands, the ephrins, act as signaling molecules regulating the migratory behavior of neurons and neural crest cells, and are implicated in tissue patterning, blood vessel formation, and tumorigenesis. On the basis of structural similarities and overlapping binding specificities, Eph receptors as well as their ligands can be divided into A and B subfamilies with orthologues found in all vertebrates. We describe here the isolation of cDNAs encoding Xenopus EphB4 receptors and show that embryonic expression is prominently associated with the developing vasculature, newly forming somites, the visceral arches, and non-neuronal tissues of the embryonic head. In a screen to identify potential ligands for EphB4 in Xenopus embryos, we isolated cDNAs for the Xenopus ephrin-B2 and -B3, which demonstrates that the Xenopus genome harbors genes encoding orthologues to all three currently known mammalian ephrin-B genes. We next performed in situ hybridizations to identify tissues and organs where EphB4 receptors may encounter ephrin-B ligands during embryonic development. Our analysis revealed distinct, but overlapping patterns of ephrin-B gene expression. Interestingly, each ephrin-B ligand displayed expression domains either adjacent to or within EphB4-expressing tissues. These findings indicate that EphB4 receptors may interact in vivo with multiple B-class ephrins. The expression patterns also suggest that EphB4 receptors and their ligands may be involved in visceral arch formation, somitogenesis, and blood vessel development.

Alleles↗
PubMed1998

The Nuclear Receptor Resource: a growing family.

Last year, the original Glucocorticoid Receptor Resource was expanded into a comprehensive project: the Nuclear Receptor Resource (NRR, http:// nrr.georgetown.edu/nrr/nrr.html ). The NRR has since been offering comprehensive information on nuclear receptor structure and function, as well as general facts of interest to the scientific community on meetings, funding and employment opportunities. The project now includes individual resources as part of a network which integrates information on glucocorticoid, androgen, mineralocorticoid, thyroid hormone, Vitamin D and peroxisome-proliferator activated receptors. Many investigators have joined the NRR network by filling the Who is who? form available in the NRR home page. This has facilitated communication among scientists in the field and dissemination of data nor otherwise published. Because several investigators have contacted NRR authors over the past few months asking for advice and materials for educational purposes, we have recently decided to include in our project an educational resource on nuclear receptors termed the 'Graphics Library'. The input and suggestions of NRR users do shape the future direction of the project, so we encourage user to give us feedback.

Computer Communication Networks↗
PubMed1997

The EphA4 and EphB1 receptor tyrosine kinases and ephrin-B2 ligand regulate targeted migration of branchial neural crest cells.

BACKGROUND: During vertebrate head development, neural crest cells migrate from hindbrain segments to specific branchial arches, where they differentiate into distinct patterns of skeletal structures. The rostrocaudal identity of branchial neural crest cells appears to be specified prior to migration, so it is important that they are targeted to the correct destination. In Xenopus embryos, branchial neural crest cells segregate into four streams that are adjacent during early stages of migration. It is not known what restricts the intermingling of these migrating cell populations and targets them to specific branchial arches. Here, we investigated the role of Eph receptors and ephrins-mediators of cell-contact-dependent interactions that have been implicated in neuronal pathfinding-in this targeted migration. RESULTS: Xenopus EphA4 and EphB1 are expressed in migrating neural crest cells and mesoderm of the third arch, and third plus fourth arches, respectively. The ephrin-B2 ligand, which interacts with these receptors, is expressed in the adjacent second arch neural crest and mesoderm. Using truncated receptors, we show that the inhibition of EphA4/EphB1 function leads to abnormal migration of third arch neural crest cells into second and fourth arch territories. Furthermore, ectopic activation of these receptors by overexpression of ephrin-B2 leads to scattering of third arch neural crest cells into adjacent regions. Similar disruptions occur when the expression of ephrin-B2 or truncated receptors is targeted to the neural crest. CONCLUSIONS: These data indicate that the complementary expression of EphA4/EphB1 receptors and ephrin-B2 is involved in restricting the intermingling of third and second arch neural crest and in targeting third arch neural crest to the correct destination. Together with previous work showing that Eph receptors and ligands mediate neuronal growth cone repulsion, our findings suggest that similar mechanisms are used for neural crest and axon pathfinding.

Animals↗
PubMed1997

Incorporation of trifluoromethionine into a phage lysozyme: implications and a new marker for use in protein 19F NMR.

Much interest is currently focused on understanding the detailed contribution that particular amino acid residues make in protein structure and function. Although the use of site-directed mutagenesis has greatly contributed to this goal, the approach is limited to the standard repertoire of twenty amino acids. Fluorinated amino acids have been utilized successfully to probe protein structure and dynamics as well as point to the importance of specific residues to biological function. In our continuing investigations on the importance of the amino acid methionine in biological systems, the successful incorporation of L-S-(trifluoromethyl)homocysteine (L-trifluoromethionine; L-TFM) into bacteriophage lambda lysozyme (LaL), an enzyme containing three methionine residues, is reported. The L isomer of TFM was synthesized in an overall yield of 33% from N-acetyl-D,L-homocysteine thiolactone and trifluoromethyl iodide. An expression plasmid giving strong overproduction of LaL was prepared and transformed into an Escherichia coli strain auxotrophic for methionine permitting the expression of LaL in the presence of L-TFM. The analogue would not support growth of the auxotroph and was found to be inhibitory to cell growth. However, cells that were initially grown in a Met-rich media followed by protein induction under careful control of the respective concentrations of L-Met and L-TFM in the media, were able to overexpress TFM-labeled LaL (TFM-LaL) at both high (70%) and low (31%) levels of TFM incorporation. TFM-LaL at both levels of incorporation exhibited analogous activity to the wild type enzyme and were inhibited by chitooligosaccharides indicating that incorporation of the analogue did not hinder enzyme function. Interestingly, the 19F solution NMR spectra of the TFM-labeled enzymes consisted of four sharp resonances spanning a chemical shift range of 0.9 ppm, with three of the resonances showing very modest shielding changes on binding of chitopentaose. The 19F NMR analysis of TFM-LaL at both high and low levels of incorporation suggested that one of the methionine positions gives rise to two separate resonances. The intensities of these two resonances were influenced by the extent of incorporation which was interpreted as an indication that subtle conformational changes in protein structure are induced by incorporated TFM. The similarities and differences between Met and TFM were analyzed using ab initio molecular orbital calculations. The methodology presented offers promise as a new approach to the study of protein-ligand interactions as well as for future investigations into the functional importance of methionine in proteins.

Bacteriophage lambda↗