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Biomedical subjects

I Fowler

Publications and source records attributed to I Fowler.

18 recordsLinked to original sources
PubMed2001

Use of 'chalk' in rock climbing: sine qua non or myth?

Magnesium carbonate, or 'chalk', is used by rock climbers to dry their hands to increase the coefficient of friction, thereby improving the grip of the holds. To date, no scientific research supports this practice; indeed, some evidence suggests that magnesium carbonate could decrease the coefficient of friction. Fifteen participants were asked to apply a force with the tip of their fingers to hold a flattened rock (normal force), while a tangential force pulled the rock away. The coefficient of friction--that is, the ratio between the tangential force (pulling the rock) and the normal force (applied by the participants)--was calculated. Coating (chalk vs no chalk), dampness (water vs no water) and rock (sandstone, granite and slate) were manipulated. The results showed that chalk decreased the coefficient of friction. Sandstone was found to be less slippery than granite and slate. Finally, water had no significant effect on the coefficient of friction. The counter-intuitive effect of chalk appears to be caused by two independent factors. First, magnesium carbonate dries the skin, decreasing its compliance and hence reducing the coefficient of friction. Secondly, magnesium carbonate creates a slippery granular layer. We conclude that, to improve the coefficient of friction in rock climbing, an effort should be made to remove all particles of chalk; alternative methods for drying the fingers are preferable.

Adult↗
PubMed2000

A comparison of continuous alendronate, cyclical alendronate and cyclical etidronate with calcitriol in the treatment of postmenopausal vertebral osteoporosis: a randomized controlled trial.

A number of drugs are now available for the treatment of established osteoporosis and have been shown to significantly increase bone mineral density (BMD). There are, however, few comparative treatment studies and, furthermore, adverse events remain a problem with some of the newer agents, particularly in the elderly, in everyday clinical practice. We report a 12 month, open labeled, randomized controlled, prospective treatment study in 140 postmenopausal women with established vertebral osteoporosis, comparing the effect of continuous alendronate, cyclical alendronate and cyclical etidronate with calcitriol in terms of gain in BMD, reduction in bone turnover markers and adverse event profile. The mean percentage increases in BMD at 12 months, at the spine and hip respectively, were: continuous alendronate 5.7%, 2.6%; cyclical alendronate 4.1%, 1.6%; cyclical etidronate 4.9%, 2.0% (p<0.0 1) and calcitriol 2.0%, 0.4% (NS). In comparison with calcitriol, the mean changes in BMD at the spine and hip respectively were greater in the other groups; continuous alendronate: 3.7% (95% CI 1.4 to 8.3), 2.2% (95% CI 0.7 to 4.0); cyclical alendronate: 2.1% (95% CI 1.2 to 6.4), 1.2% (95% CI -0.3 to 3.0); cyclical etidronate: 2.9% (95% CI 1.9 to 6.5), 1.6% (95% CI 0.9 to 3.1)). The reduction in bone turnover markers was between 26% and 32% in the alendronate and etidronate groups (p<0.01), with a trend toward greater reduction in the continuous alendronate group. Eight patients discontinued the study: 6 in the continuous alendronate group, 1 in the cyclical alendronate group and 1 in the calcitriol group. Two patients in the cyclical etidronate group were unable to tolerate the Cacit component, but continued on substituting Cacit with Calcichew. In summary, 12 months of treatment with continuous alendronate, cyclical alendronate and cyclical etidronate are effective in terms of the gain in BMD at the anteroposterior spine and total hip in a comparable treatment population. These treatments are more effective than calcitriol and were generally well tolerated. Continuous alendronate showed a trend toward a larger gain in BMD and greater suppression of bone turnover markers than the other treatment groups, but had a higher incidence of adverse events, particularly within the older subgroup. Cyclical alendronate offers a lower adverse event profile and appears to be effective in comparison with continuous treatment, and may possibly be an alternative in the elderly. However, further studies are necessary, but more importantly with fracture end-points.

Administration, Oral↗
PubMed1993

Audit of a decade of continuous ambulatory peritoneal dialysis.

We have reviewed the results of continuous ambulatory peritoneal dialysis (CAPD) in a single renal unit over the period from December 1979 to the end of 1990. Case records of 211 of the 222 patients treated by CAPD over this period were obtained and age, sex, diagnoses, duration of CAPD, and cause of death determined. We found marked effects of age and a diagnosis of atheromatous vascular disease at the start of CAPD on patient survival. For patients aged under 45 years 5-year patient survival was 78%, for those aged 45-65 it was 29% and for those aged over 65 years it was 32%. Patients with a diagnosis of atheromatous vascular disease at the start of CAPD had a 3-year survival of 25% compared with 69% for age- and sex-matched CAPD patients without such a diagnosis. Five-year technique survival was 67% if failure was defined as transfer to haemodialysis or death as a direct result of CAPD, but only 11% of patients were on CAPD continuously for 5 years. Attempts to compare our results with those from other reports were hindered by the variety of methods used to calculate patient and technique survival; we suggest that standard methods should be agreed.

Age Factors↗
PubMed1992

CAPD disconnect systems: UK peritonitis experience.

We reviewed peritonitis (P) experience of four UK units using single use Y (Freeline T.M., Baxter UK)(F) and Twinbag (Solo T.M., Baxter UK) (S) disconnect systems, which incorporate the 'Flush Before Fill' principle. We aim to show clinical achievements, in varying circumstances, in the light of previously published in vitro study results. Each unit recorded P data, i.e., rates, causative organisms, and recurrences (R) over a 12 month period (Sept 89-Aug 90). This data was then analysed by system, by unit and in total. Each unit had similar definitions for P and R, but had varying system selection criteria. Unit 1 had a fairly open criteria for F use, then became more selective at the same time as introducing S. In unit 2, F, and then S, were first choice systems for all (inc. blind diabetics). Unit 3 trains every pt. on non-disconnect System 2, then pt. choice determines if they are retained onto a disconnect system. Unit 4 had a more highly selected population. Results, expressed as episodes/patient month, were as follows: [table: see text] We conclude that it is possible to achieve a low incidence of P, especially that caused by S. epidermidis, particularly with S. It would seem the extent is related to pt. to system selection criteria. The effects of R and ES/TI need to be addressed.

Humans↗
PubMed1986

Sources of trophic factors that induce limb regeneration and prevent amputation-induced neuronal death.

Segments of 2-, 4-, 6- and 8-day neural tube, or of 15-day peripheral nerve were implanted longitudinally into limb stumps of 4-day chick embryos whose right-wing buds were amputated at the future elbow region. Stumps of amputated limbs (ALs) implanted with 7-day heart or without implant served as controls. Effects of progressively older neural tube implants (NTIs) upon ALs and host spinal cord neurons were analyzed by area measurements of the peripheral limb field (PLF) and NTI and by cell counts of the host lateral motor column (LMC). Nine days postamputation, 2- and 4-day NTIs contained many neurons and induced epimorphic regeneration in more than one-fourth of the embryos. Six-day NTIs contained few neurons and induced only tissue regeneration. Eight-day NTIs and peripheral nerve containing only non-neuronal cells were as ineffective as controls in stimulating regeneration, although peripheral nerve did cause a significant increase in the peripheral field. The NTIs of all ages and implants of peripheral nerve were equally effective in protecting LMC neurons from amputation-induced cell death in the host spinal cord. The results may indicate that neurons of the implant induce limb regeneration and non-neuronal cells of the implant protect against LMC neuronal death.

Age Factors↗
PubMed1985

Responses of host motor and sensory neurons to a neural tube implant in amputated chick limbs.

The right wingbuds of stage 23-25 chick embryos were amputated at the future elbow region and a segment of 2-day neural tube was implanted longitudinally into the limb stump of experimental embryos to induce limb regeneration. Control embryos had no implant in the amputated limb stump. To analyze effects of the neural tube implant (NTI) upon the host nervous system, quantitative determinations were made of the peripheral limb field (PLF), dorsal root ganglia (DRG) and spinal cord lateral motor column (LMC) of the amputated side for comparison with similar determinations of the unamputated side in all embryos. The PLF was estimated by determining the area of the skeletal elements of the amputated and unamputated limb of each embryo. The size of the DRG was estimated by determining the sectional-profile area of a pair of ganglia; the LMC was determined by counting the neurons on both sides of a single spinal cord segment. The PLF was less on the amputated than on the unamputated side but was significantly greater in amputated limbs that received a NTI. The size of the DRG was positively correlated with the size of the PLF in all groups, indicating the DRG was not directly affected by the NTI but did respond to target structures. The number of neurons in the LMC was not positively correlated with the PLF and was not reduced by limb amputation in embryos with a NTI. The data suggest that the NTI may have protected host spinal cord cells from the induced-cell death expected to follow limb amputation; perhaps the implant produces a neuronal survival factor.

Animals↗
PubMed1984

The threshold quantity of nerve required to induce limb regeneration in the chick embryo.

Wingbuds of 4-day chick embryos were amputated at the future elbow joint and a segment of embryonic neural tube was implanted longitudinally in the stump. The cross-sectional area and number of nerve bundles were determined in limbs in which limb regeneration occurred and compared with similar measurements in control limbs without neural tube implant. The number of nerve bundles in regenerated limbs was not significantly greater than in control limbs which did not regenerate. However, the cross-sectional area of nerve bundles was significantly greater in the limbs that had undergone regeneration. The data support the view that the amount of axoplasm available at the amputation (surface) site is the essential factor in determining the success or failure of regeneration.

Animals↗
PubMed1984

Response of amputated rat limbs to fetal nerve tissue implants and direct current.

We have previously shown that implanted fetal nerve tissue stimulates the regeneration of amputated chick limbs. The purpose of this study was to determine whether a similar phenomenon would occur in amputated rat limbs and if addition of applied direct current (DC) would affect this process. Thus, fetal nerve tissue was implanted into amputated stumps of 3-week-old rats; variable tissue regeneration was induced that was dependent on the age of the donor implant and the presence of applied DC. Twelve or 14 day fetal neural implants induced new accessory bones containing epiphyseal plates and marrow cavities and occasionally formed joint-like structures with the host humerus. Addition of DC to 12 day neural implants increased the number of new bones formed. Eighteen day neural tissue with applied DC did not induce new bone formation but stimulated the maximal elongation of the host humerus and outgrowth of nerve fibers to the cut surface. Implantation of fetal heart tissue or implantation of fetal neural tissue into unamputated limbs failed to induce new bone formation. Although true limb regeneration was not achieved, formation of new skeletal elements did occur and this effect was enhanced by applied DC.

Amputation Stumps↗
PubMed1982

Effect of augmentation of nerve supply upon limb regeneration in the chick embryo.

Limb regeneration was induced in 4-day chick embryos by implanting stage 15 neural tube into the amputated stump of the limb. In control animals, amputation alone or amputation with implant of either notochord or somites resulted in development of proximal wing segments only. In experimental animals, more than one-fourth of the animals containing viable neural tube implants developed proximal, middle, and distal limb segments. These regenerated limb segments contained muscle groups, cartilage models, and nervous structures that approximated the normal situations. Since some new parts regenerated in more than one-fourth of the cases, it may be concluded that augmentation of nerve supply is an effective method of inducing regeneration in limbs of chick embryos. Volume measurements of the neural tube implant indicate that a "critical mass" of nerve tissue may be necessary for regeneration to occur.

Animals↗