Biomedical subjects
C J Brown
Publications and source records attributed to C J Brown.
Self-evaluation of walking-track measurement using a Sciatic Function Index.
Recovery of function is of prime importance after peripheral nerve injury and repair. This paper describes a method of obtaining and measuring walking-tracks and generating a Sciatic Function Index (SFI) to quantify functional sciatic nerve recovery in the rat. The reader is provided with a series of walking-tracks to measure, analyze and compare to those analyzed by experienced observers.
Regional localization of CCG1 gene which complements hamster cell cycle mutation BN462 to Xq11-Xq13.
The human CCG1 gene, which complements the temperature-sensitive hamster cell cycle mutations BN462 and ts13, has recently been cloned and shown to be located on the X chromosome. We have used somatic cell hybrids segregating portions of multiple X--autosome translocations to localize this gene to the Xq11 to Xq13 region of the human X chromosome.
Gene on short arm of human X chromosome complements murine tsA1S9 DNA synthesis mutation.
We have created somatic cell hybrids between the temperature-sensitive mouse cell line tsA1S9 and human cell lines in order to localize the human gene (A1S9T) complementing the cell cycle defect of the murine line. Segregation of the human X chromosome is completely concordant with growth at the nonpermissive temperature. Hybrids retaining the X chromosome are temperature-resistant, whereas those without a human X are temperature-sensitive. Further hybrids made using human cell lines with X-autosome translocations indicate that the A1S9T gene is located on the short arm of the human X chromosome.
The sensory potential of free flap donor sites.
Microneurovascular techniques make transfer of innervated soft tissue a reality. The present study investigated the sensory potential of four such donor sites: volar wrist, dorsal hand, dorsal foot, and great toe. Normal moving and static two-point discrimination values for these areas are reported. A sensory reeducation protocol demonstrated that even these normal values may be improved with training. This suggests that the full potential of transferred innervated soft tissue may best be achieved by incorporating sensory reeducation routinely in the postoperative rehabilitation program.
Heritability estimates of pregnancy rate in beef cows under natural mating.
Observations of 3,029 matings over 17 yr on an Ozark upland range were used to estimate heritability of pregnancy rate in Angus, Hereford and Polled Hereford cows. Pregnancy rate, the percentage of cows exposed that produced a live calf in the spring, was transformed using the empirical logit transformation and then analyzed for each breed separately by weighted least squares using a mixed model procedure. A numerator relationship matrix for sires of cows was incorporated into the sire model to account for relationships among sires. Variation among years significantly affected pregnancy rate in all three breeds. Age of dam significantly affected pregnancy rate in the Angus and Hereford groups. Paternal half-sib estimates of heritability from the observed binary data (h2b) for pregnancy rate were calculated on first-calf heifers and mature cows for each breed. Respective h2b estimates for heifers and mature cows were .17 and .09 in the Angus group, .04 and .01 in the Hereford group and .05 and .05 in the Polled Hereford group. The heritability estimates when binary records were transformed to the probit scale (h2) were .04 +/- .003 and .02 +/- .001 for Angus, .01 +/- .002 and 0 for Hereford and .01 +/- .001 and .02 +/- .001 for Polled Hereford for heifers and mature cows, respectively. Heritability estimates in this study are in agreement with the literature, indicating little opportunity for improvement in pregnancy rate by selection within a breed.
Noninactivation of a selectable human X-linked gene that complements a murine temperature-sensitive cell cycle defect.
The human gene A1S9T, which complements the temperature-sensitive cell-cycle defect in the murine cell line tsA1S9 and which has previously been assigned to the X-chromosome short arm, is expressed from the inactive X chromosome in human/tsA1S9 somatic cell hybrids grown at the nonpermissive temperature. The Y chromosome cannot complement the defect; thus, unlike at least two other noninactivated X loci, A1S9T has no functional Y-linked homologue. As A1S9T is readily selectable in somatic cell hybrids with the tsA1S9 mouse line, this marker should be useful in isolating somatic cell hybrids containing inactive X chromosomes, or abnormal X's (active or inactive) retaining the short arm.
Androgen receptor locus on the human X chromosome: regional localization to Xq11-12 and description of a DNA polymorphism.
The gene for the androgen receptor, mutations at which cause the X-linked androgen insensitivity syndrome, has been localized to the q11----q12 region of the human X chromosome by analysis, using a cloned cDNA for the androgen receptor, of somatic cell hybrid panels segregating portions of the X chromosome. A moderate-frequency HindIII RFLP has been found which should be useful in genetic linkage analysis of the various inherited forms of androgen insensitivity.
Genetic mapping of four DNA markers (DXS16, DXS43, DXS85, and DXS143) from the p22 region of the human X chromosome.
Linkage analysis of four polymorphic anonymous DNA markers from the Xp22 region was performed using families from the Centre d'Etude du Polymorphisme Humain. The loci DXS43 (pD2) and DXS16 (pXUT23) were found to be tightly linked (theta = 0.02 at Z = 14.96) and proximal to both DXS85 (782) and DXS143 (dic56). Multipoint linkage analysis suggests the order: (Formula: see text).
Electrically evoked brainstem potentials in cochlear implant patients with multi-electrode stimulation.
The electrically evoked brainstem potential was measured in cochlear implant patients with Symbion multichannel electrode system. In the first experiment, electrodes within the implant were stimulated individually and the responses and sensitivity across electrodes and across subjects were evaluated. The typical response waveform consisted of a series of three peaks, the most prominent occurring at approximately 4 ms after stimulus onset. The amplitude of the largest peak typically showed an orderly increase with increasing current level while latency changes were relatively small. In the second experiment, two electrodes were stimulated simultaneously in order to evaluate the relative independence of the neural populations being stimulated by the different electrode pairs. The responses were compared when two electrode pairs were stimulated simultaneously with current pulses in phase and when the same electrodes were stimulated with current pulses inverted relative to each other. Both stimulation conditions showed similar growth in response amplitude with level but different sensitivity. The differences in sensitivity between these two conditions may be indicative of the degree of overlap in the stimulated neural populations.
Relationships among absolute growth rate, relative growth rate and feed conversion during postweaning feedlot performance tests.
Knowledge of the relationships between absolute growth rate (AGR), relative growth rate (RGR) and feed conversion (FCONV) of bulls in postweaning feedlot performance tests can give cattle producers important information for selecting superior sires. Weight gain and FCONV data that were collected during 16 yr were analyzed from 393 Angus and 340 Hereford bulls by 26 and 27 sires, respectively, that were individually fed in 140-d tests. Sire variance and covariance components were used to obtain heritability (h2) estimates for AGR, RGR and FCONV and the genetic correlations (rg) and phenotypic correlations (rp) among these traits. Respective mean AGR, RGR and FCONV were 1.27 +/- .14 kg/d, .4378 +/- .0395%/d and 7.32 +/- .58 kg/kg for the Angus and 1.28 +/- .12 kg/d, .4552 +/- .0388%/d and 6.56 +/- .46 kg/kg for the Hereford bulls. Estimates of h2 were similar for AGR and RGR in both Angus (.36 +/- .11 and .22 +/- .09) and Hereford (.33 +/- .11 and .20 +/- .09) bulls. The h2 estimates for FCONV were .14 +/- .07 for Angus and .13 +/- .08 for Herefords. For the Angus and Hereford bulls, respectively, rg were .86 +/- .09 and .86 +/- .13 between AGR and RGR, -.84 +/- .38 and -.74 +/- .49 between AGR and FCONV and -.84 +/- .49 and -.61 +/- .64 between RGR and FCONV. The rp were .80 +/- .03 and .68 +/- .04 between AGR and RGR, -.58 +/- .05 and -.51 +/- .05 between AGR and FCONV and -.71 +/- .04 and -.73 +/- .04 between RGR and FCONV for the Angus and Hereford bulls, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Cochlear implants in children: benefits and concerns.
Cochlear implants have been used in investigational studies with profoundly deaf children aged 2 to 18 years. Results with the 3M/House implant indicate that this device is safe and effective. The implant provides auditory detection of much of the acoustic speech signal, significant improvement in auditory discrimination compared with preimplant with hearing aids, and improved speech production skills. A longitudinal control-group study of auditory discrimination and a cross-sectional study of speech using age-matched controls support the interpretation that these improvements are due to the cochlear implant. In addition, 26 of 50 children (52%) tested for open-set word recognition and 17 of 41 (41.5%) tested for open-set sentence comprehension demonstrated such abilities using the cochlear implant. Adverse effects have been minimal. Early results from three children with the Nucleus multichannel cochlear implant clearly indicate the efficacy of that device.
MspI RFLP detected with chromosome-walk clone pXUT23-SE3.2L from DXS16 in Xp22.1-22.3.
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A comparison of AP and ABR tuning curves in the guinea pig.
AP and ABR tuning curves were measured using a forward masking paradigm in guinea pigs with chronically implanted electrodes. Measurements were made before exposure to wide-band noise and at several intervals after exposure. The noise exposure was sufficient to produce temporary threshold shifts up to 60 dB lasting several days. Results showed similar reductions in Q10, tip-to-tail ratio and slope of simultaneously recorded AP and ABR tuning curves as a function of threshold shift following noise exposure. Tuning curves based on changes in response latency are presented as well as tuning curves based on changes in response amplitude. AP and ABR latency tuning curves showed similar form and changes with hearing loss as amplitude tuning curves. The similarities between AP and ABR tuning characteristics provide evidence that the ABR is sensitive enough to peripheral changes to be useful as a tool to study auditory frequency selectivity. The similarities between amplitude and latency tuning characteristics suggest that information regarding frequency selectivity of the auditory system can be obtained using response latency as well as response amplitude.
A comparison of the karyotypes of six species of the genus Macaca and a species of the genus Cercocebus.
Karyotypes from 72-hour whole blood cultures were compared for six species of macaques (Macaca arctoides, M. fascicularis, M. mulatta, M. nemestrina, M. nigra, and M. radiata) and one species of mangabey (Cercocebus atys). G-bands, sequential C-bands, and late replication patterns were studied. Results showed a variation in a single chromosome pair which differentiated C. atys from the macaques. Heteromorphic variation in silver stained nucleolar organizing regions was seen between and within individuals. This data supports previous work showing the highly conserved nature of the chromosomes of the subfamily Cercopithecus.
Ultrastructural analysis of experimental allergic uveitis in rabbit.
Bilateral posterior uveo-retinitis was induced in 6 pigmented rabbits by unilateral subconjunctival injection of 50 micrograms of retinal soluble antigen (S-antigen) in complete Freund's adjuvant. Ultrastructurally the inflammation revealed four distinct phases of target cell destruction in the retina. Initially there was a coagulative necrosis of the outer segments of the photoreceptor cells, followed by phagocytosis of these outer segments by mononuclear cells. Next, there was hydropic degeneration and necrosis of the inner segments and the cell bodies, and finally there was proliferation of the retinal pigment epithelium and enlargement of the Müller cells to replace the necrotic photoreceptors. The localized damage to the photoreceptor cells indicates that these cells are the target site in the inflammation induced by S-antigen.
Maternal behavior of beef cows at parturition.
Over an 11-yr period maternal behavior, calf birth weight and calf condition were recorded within 24 h for 2,684 parturitions. Maternal behavior was rated on a scale from 1 to 11, where 1 indicated extreme aggressiveness and 11 indicated no maternal attentiveness. Birth condition was rated on a scale from 1 to 9, with 9 being fattest and 1 thinnest. Respective breed means of Hereford, Angus, Charolais and Red POll were 6.2, 5.3, 6.0, and 5.7 for maternal behavior rating; 30.6, 27.3, 39.2 and 32.6 kg for birth weight, and 5.5, 4.7, 5.6 and 5.5 for birth condition. Heritability estimates for maternal rating, birth weight and birth condition were .06 +/- .01, .48 +/- .02 and .19 +/- .01, respectively. Genetic correlations between maternal rating and birth weight and condition were .04 +/- .05 and -.02 +/- .06, respectively. These results suggest that, in the population of cows studied, nongenetic influences were the primary cause of differences in aggressiveness of cows at parturition.
Trends of performance in Arkansas cooperative beef-bull performance tests from 1962 through 1982.
Individual records of performance of 2787 bulls in cooperative beef-bull performance tests from 1962 through 1982 were analyzed to determine trends in final weight, average daily gain, daily feed consumption and gross feed efficiency. Data from Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds were analyzed separately. Performance-test procedures and the ration fed remained the same in all tests. Least-squares means by year, adjusted for location of test, initial weight, initial age and initial condition score, were regressed on time to determine average yearly change in the traits. Yearly changes for Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds in final weight were 3.3, 1.6, 3.3, 2.5, and 2.6 kg, respectively; in average daily gain and yearly changes were .02, .01, .02, .02, and .02 kg, respectively; in daily feed consumption the yearly changes were .08, .03, .09, and .04 kg, respectively; and in feed per kg gain the yearly changes were -.08, -.04, -.05, -.03, and -.07 kg, respectively. Because the test procedures were the same in all years, these trends represent genetic progress made by the Arkansas beef industry toward faster-gaining, more efficient cattle.