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Biomedical subjects

R Price

Publications and source records attributed to R Price.

192 records · Page 11Linked to original sources
PubMedDate not supplied

Fixation effects on synaptic vesicle density in neuromuscular junctions of young and old mice.

It was previously reported that in soleus neuromuscular junctions of old mice, synaptic vesicle density was decreased while transmitter release was increased (compared to results in young mice). In the present study, two hypotheses that might resolve this disparity were tested. The first was that the density of readily releasable vesicles close to the preterminal membrane, rather than those in the whole terminal, would correlate with the physiological results. This hypothesis was excluded because both vesicle density in the 200 nm region just within the presynaptic terminal membrane, and total vesicle density were similarly reduced in old soleus junctions. The second hypothesis was that more transmitter was released during fixation at old than at young neuromuscular junctions, leading to an age-related depletion of vesicles. This was tested by counting vesicles in muscles fixed after transmission block was attained in Krebs solution lacking calcium, and by direct recording of quantal release during conventional fixation. This second hypothesis was excluded: in neuromuscular junctions exposed to zero-calcium Krebs solution before fixation, the age-related reduction in vesicle density was still present, and intracellular recording revealed only a slight increase in quantal transmitter release during fixation. Therefore, as discussed, other mechanisms must be considered.

Aging↗
PubMedDate not supplied

Artesunate and mefloquine in the treatment of uncomplicated multidrug-resistant hyperparasitaemic falciparum malaria.

Oral artesunate is the most effective treatment for uncomplicated hyperparasitaemia in falciparum malaria. To assess the contribution of mefloquine to therapeutic efficacy in an area endemic for mefloquine-resistant Plasmodium falciparum, an open randomized comparison of a 5 d course of oral artesunate (total dose 12 mg/kg) with and without a single dose of mefloquine (25 base mg/kg) was conducted in 100 adults and children with uncomplicated hyperparasitaemia (> 4% parasitized red blood cells). Both regimens were well tolerated and gave equally rapid clinical responses (84% of patients were aparasitaemic and 96% were afebrile within 48 h), but the recrudescence rate assessed at day 42 was 6% in those receiving artesunate with mefloquine compared to 36% in those receiving artesunate alone (adjusted hazard ratio 7, 95% confidence interval [95% CI] 2-32; P < 0.01). In addition, the efficacy of a 7 d course of artesunate, with and without the addition of mefloquine, was monitored in 178 patients who were not part of the randomized comparison. The failure rate was again lower in those receiving artesunate and mefloquine--7% (95% CI 2-13) compared with 26% (95% CI 8-44) in patients treated with artesunate alone. An oral regimen of 5 d or more of artesunate, together with mefloquine (25 mg/kg) given on day 2, is an effective treatment for uncomplicated hyperparasitaemic falciparum malaria in this area of high level multidrug resistance.

Administration, Oral↗
PubMedDate not supplied

Survival of Apligraf in acute human wounds.

Apligraf consists of bovine collagen dermis seeded with allogeneic male fibroblasts and keratinocytes. It is been shown to promote healing, but the length of persistence and pathological features have not been characterized previously in acute wounds. Forty-eight deep dermal wounds were created and Apligraf, a split-skin graft (SSG), or a dressing was applied. Biopsies of wounds were taken for immunohistochemical analysis and polymerase chain reaction was performed to detect the Y chromosome from Apligraf cells in 14 female wounds. Male allogeneic DNA was detected in wounds for the first 4 weeks. All subsequent time points were negative apart from one biopsy at 6 weeks. The wounds took 4-9 weeks to heal, with the Apligraf exhibiting no features of engraftment. This was in contrast to the rapid healing seen in the SSG control group. Histology revealed a more intense cellular infiltrate, but less vascularization below Apligraf compared with controls. Evidence of an epidermal-mesenchymal interaction was observed. This is the first article to elucidate the survival of Apligraf allogeneic cells in acute wounds in immunocompetent human subjects for up to 6 weeks and demonstrates that in the management of acute surgical wounds, Apligraf has a role only as a temporary biological dressing.

Bioartificial Organs↗
PubMedDate not supplied

Comparison of speech-evoked v tone-evoked P300 response: implications for predicting outcomes in patients with traumatic brain injury.

The P300 response is a cognitive event-related potential recorded over the scalp. The tone-evoked P300 response has been used to predict outcomes of patients with brain injury. However, it may lead to false predictions because some normal people have a very small tone-evoked P300 response. It is hypothesized that speech may generate a more robust P300 response than tones. A voice-generator prototype was designed for this study. The rare speech signal was the word "mommy" in a female voice. The common signal was a 1000-Hz tone. Twenty-two normal adults (11 males, 11 females; age range, 18-60 yr) were tested for both speech-evoked and tone-evoked P300 responses. Speech-evoked P300 responses had significantly larger amplitudes (mean, 12.1 microV) than the tone-evoked responses (mean, 5.9 microV; P < 0.0001). Six subjects with brain injury were also tested using the same protocol: two subjects with severe brain injury showed no response to either stimulus. Both died within 1 wk after the testing. Although two subjects with moderate brain injury could not complete the testing because of agitated behavior, two other subjects with mild traumatic brain injury showed a larger speech-evoked than tone-evoked P300 response. The speech-evoked P300 response may be promising in predicting outcomes of patients with brain injury.

Adolescent↗
PubMedDate not supplied

Gonococcal infection of the neovagina in a male-to-female transsexual.

BACKGROUND AND OBJECTIVES: To describe a case of asymptomatic gonococcal infection of the surgically constructed vagina of a male-to-female transsexual prostitute. STUDY DESIGN: Case report. CONCLUSION: Although the stratified squamous epithelium that lines the neovagina is normally resistant to infection with Neisseria gonorrhoeae, this diagnosis should be considered in this population, particularly if working in the commercial sex industry.

Adult↗
PubMedDate not supplied

Subcellular distribution and storage form of rat renal renin.

The subcellular distribution and nature of rat renal renin has been investigated by means of analytical subcellular fractionation and gel filtration on Sephadex G-100. During differential centrifugation, renin activity was recovered mainly in soluble and heavy mitochondrial fractions. On sucrose gradient centrifugation in either a conventional or in a B XIV zonal rotor, renin activity equilibrated at 1.54 M sucrose and was partially resolved from marker enzymes for mitochondria (succinate dehydrogenase), lysosomes (acid phosphatase), plasma membranes (alkaline phosphatase), and peroxisomes (catalase). On gel filtration of the soluble or extracts of the renin-granular fractions on Sephadex G-100, renin activity eluted as a single peak with an apparent molecular weight (MW) of 42,000; no change in activity was found when these fractions were acidified to pH 3.0. When kidney homogenates were prepared in the presence of the proteolytic inhibitor N-ethylmaleimide (NEM, 10 mM), whereas the renin from the granular fractions displayed a MW of 44,000, that from the soluble fraction was apparently higher (69,000). Addition of NEM (10 mM) to the soluble fraction previously shown to contain only the low MW form of renin also resulted in an apparently high MW form of renin. These results indicate that rat renal renin is associated with a mechanically fragile, distinct type of subcellular organelle. Renin within this structure is of the low MW form and is not acid activatable. The soluble fraction, however, contains a factor(s) that, in the presence of NEM, combines with the low MW renin to form a complex of apparently high MW.

Acids↗
PubMedDate not supplied

Controlled release from cylindrical microstructures.

Microtubules formed from diacetylenic phosphatidyl-cholines can be made rugged and solvent resistant through electroless deposition of metals (Rudolph et al. 1990). Once dried tubules can capture a range of materials by capillary action when added to a hydrating medium, thus retaining and controlling the release rates of these materials. We report the encapsulation in tubules of a mixture of tetracycline, epoxy monomers and polymers and their in vitro release kinetics in both dynamic and static environments.

Delayed-Action Preparations↗
PubMedDate not supplied

Design and validation of an instrument package designed to increase the reliability of ankle range of motion measurements.

OBJECTIVE: To validate a novel device termed the equinometer, which is designed to accurately measure ankle dorsiflexion. DESIGN: Test retest reliability analysis using serial measurements of dorsiflexion endpoint in a group of normal individuals. SETTING: Motion analysis laboratory. PARTICIPANTS: Ten healthy individuals. PRIMARY OUTCOME MEASURE: The mean and standard deviation of the absolute difference in dorsiflexion endpoint for the group. RESULTS: The mean absolute change in dorsiflexion endpoint for the group was 0.45 degrees with a standard deviation of 0.43 degrees. CONCLUSIONS: With the use of the device described, the mean change in dorsiflexion endpoint was well within acceptable clinical limits. The reliability of measurements obtained with the equinometer exceeds that which has been published with other techniques and devices.

Adult↗