Biomedical subjects
Publications and source records attributed to D A Smith.
The restoration of continence in the homebound client often depends on the nurse's conviction that restoration is possible. In many cases, a thorough assessment of the incontinent client will not only identify the cause of incontinence, but will also present a framework for its treatment. The first step is simply the recognition of the problem and the desire for the nurse to facilitate change.
Healing of cutaneous wounds was studied in groups of common garter snakes (Thamnophis sirtalis) held at 13.5 degrees C, 21 degrees C and 30 degrees C. Linear unsutured incisions and circular excisional wounds were evaluated two, five, and ten days after surgery, while linear sutured and unsutured incisions and circular and square excisional wounds were studied three and six weeks after wound production. The sequence of events during healing was the same for all experimental situations. The epithelial margins of the wounds moved freely over exposed epaxial muscle until an exudate of fibrin and inflammatory cells caused adhesion. Heterophils and macrophages were present two days after wounding. Heterophils were present throughout the wound while macrophages were concentrated in areas containing fibrin and proteinaceous exudate. Fibroblasts moved laterally into the wound from the adjacent dermis producing a flat dermal scar oriented parallel to the wound surface. Epithelial cell hypertrophy and hyperplasia occurred in a zone extending up to 1.5 mm from the margin of the wound. A tongue of flattened epithelial cells extended across the wound surface, mingling with the superficial crust and migrating over eosinophilic fibrillar material. Maturation of the new epithelium, indicated by formation of a distinct basal layer, rounding of superficial cells and keratin production, began at the wound margins before the epithelial spurs linked. The epithelium over healed wounds appeared normal, but the dermis did not reorganize to form scales. Reptilian and mammalian healing differ in the character of the inflammatory reaction, the pattern of fibroplasia, and the interaction between epithelial and dermal repair.
The effects of ambient temperature (13.5 degrees C, 21 degrees C, 30 degrees C) and type of wound on healing of skin wounds were evaluated in common garter snakes (Thamnophis sirtalis). Linear unsutured incisions and circular excisional wounds were evaluated grossly and microscopically in three snakes held at each temperature at each of two, five and ten days after surgery. Linear sutured and unsutured incisions and circular and square excisional wounds were similarly evaluated three and six weeks after wound production in groups of six snakes held at each temperature. The rates of stabilization of wound margins, scab formation, migration and maturation of the regenerating epithelium, resolution of dermal inflammation, and fibroplasia varied directly with temperature. The inflammatory reaction to wounding was similar in character and intensity in snakes held at all three temperatures two days after surgery. Unsutured linear incisions, compared to sutured incisions, tended to have more rapid epithelial maturation and a less intense inflammatory response. Healing of square and circular excisional wounds was similar; contraction of round wounds was slightly more irregular and, at a few observations, dermal maturation was slower and inflammation more widespread. It was concluded that healing of skin wounds can be accelerated by holding reptiles at the upper end of their voluntary temperature range. Wounds, if possible, should be created along the axis of lines of skin tension. Suturing small incisional wounds may not be advantageous.
The effects of four topical medications on the rate and character of healing of cutaneous wounds were studied in six common garter snakes (Thamnophis sirtalis) held at an ambient temperature of 30 degrees C. Two sets of five 6 to 8 mm round excisional wounds, four test and one control site in each set, were created on the dorsolateral body wall of each snake. Wounds were examined daily and treated for ten days, then the snakes were killed and sections of all wounds were examined by light microscopy. Composite scores, derived by ranking each treatment group in relation to the control group (control score = 0) for each of 22 characteristics associated with wound healing, were used to compare the overall effects of each treatment. Statistical comparisons were made between groups for 20 characteristics. Wounds treated with a polyurethane film merited a score of +12 and had significantly more advanced healing than untreated controls for three characteristics. Wounds treated with an ointment containing scarlet red scored +6 but healing was not significantly greater than controls. Wounds treated with an antibacterial spray powder and an antibacterial ointment healed more slowly than controls and had scores of -6 and -12 respectively.
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The mechanical and thermal properties of Huxley's 1957 sliding filament model for striated muscle contraction are reconsidered, with emphasis on general relationships between two-state models and muscle behaviour. New empirical forms for the rate functions f(x) and g(x) are proposed, which give an improved fit to experiments. A specific procedure, based on the shortening heat, for determining model parameters is described and applied to various choices of rate functions. The change in slope of the tension-velocity curve observed by Katz is shown to require at least one discontinuity in the binding rate f(x), and a general formula is given. The two-state model also gives a symmetric cusp in the ATP-rate vs velocity curve at v = 0. The theory is extended to time-varying situations and applied to transient responses following isometric activation by tetanus (including latency relaxation), and unloaded and after-loaded contractions. The early burst of heat production can also be fitted by assigning appropriate values to the heats of binding and dissociation.
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Intracellular recordings from granule cells of the rat dentate gyrus show neuropeptide Y (NPY) applied by pressure ejection from pipettes containing 1.2-12 microM by pressures of less than 200 kPa for 1-5 s in duration to consistently evoke membrane depolarisations accompanied by a reduction in membrane resistance. The depolarisations were accompanied by an increase in excitability. Since the depolarisations evoked by NPY were not attenuated by either tetrodotoxin or kynurenic acid a direct excitatory action of NPY is postulated.
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1. An improved method of preparing wedges of cerebral cortex and corpus callosum from 500 microM thick coronal sections using mouse brain is described. 2. The characteristics of mixing in the two compartment baths is fully reported. 3. Cortical tissue could be depolarized relative to callosal tissue by superfusion of N-methyl-D-aspartate (NMDA), quinolinate, kainate or quisqualate. 4. At higher concentrations of agonists the depolarization was followed by a small hyperpolarization. This hyperpolarization was abolished by 5 microM ouabain. 5. Neither TTX (1 microM) nor bicuculline (50-62.5 microM) significantly affected the amplitude of the responses to the excitatory amino acids. 6. Responses to NMDA and quinolinate were selectively reduced by magnesium ions, 2-amino-5-phosphonovalerate or ketamine.
Components of the dipstick urinalysis (urine urobilinogen and urine bilirubin) are often used by emergency physicians to screen for the need to obtain liver function tests in many clinical situations. A prospective observational study was conducted to evaluate the sensitivity, specificity, and predictive properties of spot urine bilirubin and urobilinogen assays in the emergency department as screening test for serum liver function test (LFT) abnormalities. Of 122 patients, abdominal pain was the indication for laboratory evaluation in 54%; jaundice and constitutional symptoms were the indication in 29%. Overall sensitivities for both urine assays were 70% to 74% for serum bilirubin, but 43% to 53% for other LFTs; specificities were 77% to 87% for both urine screens. Positive predictive values show that the urine assays were 83% to 86% reliable for detecting at least one LFT abnormality. Negative predictive values were 85% for both urine assays for serum bilirubin elevations, but lower for other LFTs. Urine urobilinogen has its greatest clinical utility as a screen when a normal/abnormal threshold of 2.0/4.0 mg/dL is used.
The measurement of broadband ultrasonic attenuation (BUA) in the os calcis, which consists of predominantly trabecular bone, has been compared by others with single photon absorptiometry of forearm cortical bone. We have compared BUA in 24 female subjects with the separate measurement of trabecular and cortical bone in the distal radius using quantitative computed tomography (QCT). BUA was highly significantly correlated with each of the measurements in the radius (P less than 0.001). Paradoxically, BUA was found to be best correlated with the bone mass per unit length in the radial shaft (r = 0.85) rather than with radial trabecular bone (r = 0.66). The degree of correlation was not sufficient to predict radial bone mass accurately in individuals. Broadband ultrasonic attenuation, however, appears to be a useful measurement of bone in the appendicular skeleton.
A transposon Tn917 insertion between gerE and ilvB has identified a new developmental locus, gerM, in Bacillus subtilis. gerM96::Tn917 affects both sporulation and germination. DNA on either side of the transposon has been cloned and includes the previously cloned sdhC and gerE loci. gerE terminates 2.1 kb from the end of the transposon. The gerM96::Tn917 mutant is oligosporogenous, yielding approximately 1% of the number of wild-type heat resistant spores in liquid medium and 10% on solid medium. Six hours after the onset of sporulation alkaline phosphatase and glucose dehydrogenase levels were 90% and 7%, respectively, of those of the wild-type. At this time 50% of the mutant cells were still dividing. The occurrence of multiple polar septa and 'pygmy' cells suggested a block at stage II of sporulation. Following addition of germinants, mutant spores prepared on nutrient agar lost heat resistance normally but released slightly less dipicolinic acid than wild-type spores. They also showed only partial loss of optical density, associated with a phase-grey appearance and striations in the cortex suggesting partial degradation. Expression of the gerM gene was monitored by production of beta-galactosidase encoded by a promotorless lacZ gene fused to the gerM96::Tn917 insertion. It occurred 1.5-4 h after commencement of sporulation. Transcription was directed from a promoter on the gerE side of gerM and was unaffected by a mutation in the gerE gene.
Nicotine [(-)-nicotine di(+)-tartrate 1-50 microM] produced depolarization of motoneurones as recorded from ventral roots of immature (1-5 day old) rat hemisected spinal cord preparations. This action of nicotine was accompanied by marked desensitization which persisted for at least 2 h following a 2 min application. Ventral roots sectioned from the spinal cord, which were sensitive to glycine, failed to respond to nicotine. Blockade of regenerative electrical activity with tetrodotoxin produced a mean reduction of 39% in the response to 10 microM nicotine. In order to avoid desensitization, blocking agents were tested for their ability to suppress the initial response to a 2 min application of 10 microM nicotine (0.58 mV +/- 0.07 s.e. mean, 21 preparations) in 4 or more naïve preparations. Responses to nicotine (10 microM) were significantly reduced by 10 microM hexamethonium and were abolished by 250 microM hexamethonium but were resistant to the following antagonists:- atropine (1 microM), phentolamine (2 microM), strychnine (10 microM), kynurenic acid (2 mM) and a mixture of bicuculline (50 microM) and picrotoxin (50 microM). It is concluded that the depolarizing responses to nicotine may be due to the presence of nicotinic receptors either on the motoneurone membrane or on nerve terminals adjacent to motoneurones which release an unidentified neurotransmitter.
The nasal absorption of a range of water-soluble compounds with different molecular weights, 4-oxo-4H-1-benzopyran-2-carboxylic acid (mol. wt 190), p-aminohippuric acid (mol. wt 194), inulin (mol. wt 5200) and dextran (mol. wt 70,000), has been investigated in the male Wistar rat. Compounds were instilled into the nasal cavities of anaesthetized animals, and for comparison, similar doses were administered intravenously. Serial samples of bile and urine were collected for up to 6 h. Nasal absorption, estimated by comparison of the extent of excretion in bile and urine following intranasal and intravenous administration, was 100% for 4-oxo-4H-1-benzopyran-2-carboxylic acid (1 mg kg-1), 75% for p-aminohippuric acid (1 mg kg-1), 15% for inulin (0.1 mg kg-1) and 2.8% for dextran (0.25 mg kg-1). The log molecular weight gave a good linear correlation with the log per cent intranasally absorbed (correlation coefficient of -0.996). From the molecular weight relationship, these data infer aqueous channel mechanisms for the nasal absorption of water-soluble compounds.