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S J Jones

Publications and source records attributed to S J Jones.

At least 145 records · Page 8Linked to original sources
PubMed1992

Tactile interference differentiates sub-components of N20, P20 and P29 in the human cortical surface somatosensory evoked potential.

Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded from up to 64 locations on the exposed cortical surface in 19 patients undergoing intracranial surgery for epilepsy and/or tumour removal. In view of previously described 'interference' effects on scalp SEPs, a continuous light tactile stimulus was applied to the palm and the first 3 digits of the stimulated hand in order to try to differentiate components due to input from cutaneous and other sensory receptors. The first cortically generated potentials, N20 at postcentral locations and P20 precentrally, could each be resolved into 2 subcomponents separated by about 2.5 msec. The later subcomponent was consistently the more attenuated by the interfering stimulus and is postulated to be due to input from rapidly adapting cutaneous mechanoreceptors. The earlier subcomponent could be due to input from muscle afferents or from slowly adapting cutaneous receptors which the interfering stimulus would have activated to a lesser degree. In 2 cases the P29 potentials recorded from regions of the postcentral gyrus were dissociated. In one case the potentials recorded at adjacent electrodes were attenuated to differing degrees, and in the other the effect was maximal at different locations when the thumb, index and middle fingers were stimulated separately. The method therefore appears capable of distinguishing regions of the postcentral gyrus concerned with cutaneous input from different parts of the hand.

Adolescent↗
PubMed1992

Rapid neural growth: calcitonin gene-related peptide and substance P-containing nerves attain exceptional growth rates in regenerating deer antler.

Deer antler is a unique mineralized tissue which can produce very high growth rates of > 1 cm/day in large species. On completion of antler growth, the dermal tissues which cover the antler are shed and the underlying calcified tissue dies. After several months the old antler is discarded and growth of a new one begins. It is known that deer antlers are sensitive to touch and are innervated. The major aims of this study were to identify and localize by immunohistochemical techniques the type of innervation present, and to find out whether nerve fibres could exhibit growth rates comparable to those of antler. We have taken tissue sections from the tip and shaft of growing Red deer (Cervus elaphus) antlers at three stages of development; shortly after the initiation of regrowth, the rapid growth phase, and near the end of growth. Incubation of tissue sections with antisera to protein gene product 9.5 (a neural cytoplasmic protein), neurofilament triplet proteins (a neural cytoskeletal protein), substance P and calcitonin gene-related peptide (both of which are present in and synthesized by sensory neurons) showed the presence of immunoreactive nerve fibres in dermal, deep connective and perichondrial/periosteal tissues at all stages of antler growth. The sparse distribution of vasoactive intestinal polypeptide-like immunoreactivity was found in dermal tissue only at the earliest stage of antler development. Nerve fibres immunoreactive to neuropeptide Y, C-flanking peptide of neuropeptide Y and tyrosine hydroxylase, all present in postganglionic sympathetic nerves, were not observed at any stage of antler growth. Nerves expressing immunoreactivity for any of the neural markers or peptides employed could not be found in cartilage, osteoid or bone. These results show that antlers are innervated mainly by sensory nerves and that nerves can attain the exceptionally high growth rates found in regenerating antler.

Animals↗
PubMed1992

Effect of retinoic acid on the resorptive activity of chick osteoclasts in vitro.

Mixed cell suspensions mechanically isolated from the long-bones of day 20 prehatch chicks were cultured for 24 h on bone and sperm whale dentine slices in the presence of 0, 10, 100, and 1000 nM retinoic acid (RA). Significant inhibitions in the numbers of discrete lacunae resorbed per dentine slice, and in the ratio of lacunae per tartrate-resistant acid phosphatase-positive multinuclear cell were observed with all concentrations of RA studied. Semi-automated, 3-dimensional analysis of 733 pits was performed on one series of experiments using a tandem scanning (confocal) microscope, interfaced to an image analyzing computer. The majority of lacunae were small and unilocular; the plan areas of 90% of control pits were below 500 microns 2. Small but statistically significant increases in lacunar areas, but not mean or maximum depths or volumes, were observed in the presence of 10 and 100 nM RA; however, these changes were much smaller than the magnitude of the decrease in pit numbers. Thus, the overall effect of RA in this system was inhibitory. Our findings contrast with the well known stimulatory action of retinoids on bone resorption both in vivo and in organ culture, but may parallel the inhibitory effects of prostaglandins observed in disaggregated osteoclast systems.

Animals↗
PubMed1992

Microscopy of bone cells, bone tissue, and bone healing around implants.

Newer methods of scanning microscopy using both light and electrons are particularly relevant to the study of bone cells, bone matrix organization, matrix mineralization, bone modeling and remodeling, and the adaptation of cells and matrix to implants. Most of such studies are conducted on retrieved implants, at least after the death of the related tissue. Because the retention of the tissue-implant relationship in such preserved tissue is crucial for critical evaluation of the implant, methods based on the study of flat surfaces of embedded tissue blocks are very important. Using electrons, the backscattered electrons in a scanning electron microscope can be employed to evaluate mean atomic number (density) and cathodoluminescence can identify polymers and fluorescent labels. Using light, confocal microscopical techniques permit the examination of layers deep to the block face. Confocal reflected and fluorescence methods allow the study of cell behavior upon both transparent and opaque substrates in the laboratory. Examples of the above are presented and interpretation problems discussed. Current experiments are aimed at enabling the study of bone wound healing and bone adaptation to implanted materials in vivo, through the implantation of optical quality windows and/or newly conceived and designed microscopical objective lenses.

Animals↗
PubMed1992

Response time of broiler chickens to cimaterol: meat tenderness, muscle composition fiber size, and carcass characteristics.

The response time to cimaterol (CIM), a beta-adrenergic agonist, by broiler chickens for carcass characteristics, muscle composition, muscle fiber size, catheptic enzyme activity, and tenderness was determined. Two trials were conducted in which chickens were fed a control diet (CON) containing 0 ppm of CIM or a diet containing 1 ppm of CIM. Trial 1 consisted of 55, 31-d-old broiler chickens individually fed for up to 48 h. At 0, 6, 12, 18, 24, and 48 h, five CON and five CIM-fed chickens were killed. Trial 2 consisted of 160, 33-d-old broiler chickens group-fed for up to 14 d. At 2, 4, 6, 8, 10, 12, and 14 d, 10 CON and 10 CIM-fed chickens were killed. The breast muscle (BM) and leg muscle (LM) weight, cathepsin B and L activities, DNA, RNA, and protein concentration, and BM shear force value (SFV) were measured in both trials. Thigh muscle (TM) SFV were measured in Trial 2 only. Fiber size of BM was measured (five birds per treatment) at d 2, 6, 10, and 14. In Trial 1, BM weight and SFV were lower in CIM-fed birds at 6 h (P less than .05). In Trial 2 BM SFV were higher at d 8 (P = .06) and d 10 (P less than .05) in CIM-fed chickens. The SFV of CIM-fed chickens were higher at d 4, 8, 10, 12, and 14 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1992

Behaviour of osteoclasts in vitro: contact behaviour of osteoclasts with osteoblast-like cells and networking of osteoclasts for 3D orientation.

The cell-cell contact-induced behaviour of osteoclasts and osteoblasts in vitro was investigated by time-lapse videomicroscopy. Contact interactions of osteoclasts with autologous cells, derived mostly from chick but also from rat bones, included contact inhibition, failure of contact inhibition, contact guidance along stabilised edges of other cells, and underlapping of other cells. Message-mediated contact behaviour (MMCB) between osteoclasts and autologous osteoblastic cells resulted, after a time delay, in zeiosis of the osteoblast-like cell which could continue, or even begin, after the osteoclast broke contact, leading to retraction of the cell and occupation of its position by the osteoclast. MMCB may play a part in the breaching of the osteoblastic sheet by osteoclasts and, in general, in the malignant spread of neoplastic cells. Two or more osteoclasts were often joined by connecting and coordinating tubules (CCTs) of varied, and varying, lengths and widths. Osteoclasts could travel along the CCTs in both directions, or send nuclei through them. The CCTs became temporarily attached to the surface of other cells, or to the substrate, then acting as a temporary anchorage for orientation and for the return of the cell to the same spot. The dynamics of osteoclastic behaviour suggest that such a networking of osteoclasts is valuable for the 3D coordination of their role in bone turnover.

Animals↗
PubMed1991

Analysis of ancient bone DNA: techniques and applications.

The analysis of DNA from ancient bone has numerous applications in archaeology and molecular evolution. Significant amounts of genetic information can be recovered from ancient bone: mitochondrial DNA sequences of 800 base pairs have been amplified from a 750-year-old human femur by using the polymerase chain reaction. DNA recovery varies considerably between bone samples and is not dependent on the age of the specimen. We present the results of a study on a small number of bones from a mediaeval and a 17th-century cemetery in Abingdon showing the relation between gross preservation, microscopic preservation and DNA recovery.

Bone and Bones↗
PubMed1991

Intraocular pressure asymmetry in a population tested with the Pulsair non-contact tonometer.

Intraocular pressure asymmetry as measured by noncontact tonometry (NCT) was analysed in a population of 874 individuals aged over 50 years. In both males and females the intraocular pressure (IOP) measured in the right eye exceeded that of the left. Pressure asymmetry followed a normal distribution in a population subgroup known to have normal fields, discs and pressures. The 95% confidence intervals for the equation R IOP--L IOP in normals were 0.63+ or -5.46 mmHg when the mean of four pulses per eye were used to calculate the IOP, increasing to 0.80+ or -6.56 mmHg for two pulses per eye (thus expanding the limits by 20%). The range of asymmetry for NCT in normals therefore exceeds that reported for Goldmann applanation tonometry. Asymmetry was greater in females than males. Knowledge of the normal range of IOP asymmetry in each sex will help glaucoma screeners using NCT in their decision as to when to refer. A minimum of four pulses per eye should be used to assess the IOP when screening.

Aged↗
PubMed1991

Maximising the sensitivity and specificity of non-contact tonometry in glaucoma screening.

Data from a glaucoma screening study involving 88.5% of the population age 50 and over of a single handed general practitioner were reanalysed to determine the effect of altering the protocol for intraocular pressure assessment and the effect of changing the referral threshold. The predictive power of the Keeler Pulsair noncontact tonometer was found to decrease from 22.5% at four pulses per eye to 12.3% when only one pulse per eye was used, with a reduction of sensitivity from 91.7% to 75%. The sensitivity of the same device fell from 91.7% if all patients with an IOP greater than 21 mmHg were deemed as having a positive screen, to 41.6% when only patients with an IOP greater than 26 mmHg were considered for referral. To create a balance between high sensitivity and acceptable predictive power of a positive result in a population where 50% of glaucoma sufferers are known prior to screening, we advise that four pulses per eye should be used with an IOP of greater than 22 mmHg used as the significant finding indicating that the patient required referral.

Glaucoma↗
PubMed1991

Correlation of SEP abnormalities with brain and cervical cord MRI in multiple sclerosis.

In 31 patients with definite or suspected multiple sclerosis (MS) presenting with a cervical cord syndrome, somatosensory evoked potentials (SEPs) were recorded to median and posterior tibial nerve stimulation, using cephalic and noncephalic reference electrodes. Magnetic resonance imaging (MRI) of the brain and cervical spinal cord was performed, the latter in sagittal and axial views. SEPs were abnormal in 67.7% of patients, whereas MRI showed cervical cord lesions in 74.2% and intracranial lesions possibly involving the somatosensory pathways in 64.5% of cases. A significant correlation was found between abnormalities of cervical (N13) and cortical (N20) potentials following median nerve stimulation with Fz reference and MRI abnormalities involving the ipsilateral or posterior half of the cervical cord, but not the contralateral or anterior half. The N13 potential, recorded from the low cervical region to a supraglottal reference, was most frequently abnormal in patients with MRI lesions at C6 or C7, whereas P14, recorded from the scalp to a clavicle reference, was most often affected by lesions at Cl or the cervicomedullary junction. Abnormalities of the cortical P40 to tibial nerve stimulation were less significantly correlated with cervical MRI lesions. The latency of N20 measured from N9 at the clavicle and the absolute latency of P40 were significantly correlated with the length of MRI abnormalities in the ipsilateral cervical cord. No significant correlation was observed between SEP abnormalities and brain MRI lesions, which it was considered might possibly involve the intracranial somatosensory pathways. It was concluded that (1) the morphological lesions seen in MRI of the cervical cord usually give rise to appropriate electrophysiological deficits, but the occasional finding of a widespread MRI lesion with normal SEP suggests that myelin damage is not the only or the major factor responsible for abnormal MRI signal; and (2) 'clinically silent' lesions apparently involving the radiations and other sensory structures of the brain appear not to give rise to detectable SEP abnormalities, using the methods of the present study.

Adult↗
PubMed1991

The pathophysiology of acute optic neuritis. An association of gadolinium leakage with clinical and electrophysiological deficits.

Eighteen patients with acute optic neuritis underwent optic nerve magnetic resonance imaging (MRI) before and after injection of gadolinium-diethylene triamine pentacetic acid (Gd-DTPA). Ten were re-examined 4 weeks later. Leakage of Gd-DTPA across the blood-optic nerve barrier was a consistent finding in the acute lesion, and its presence was associated with abnormal visual acuity and colour vision, retro-ocular pain on eye movement, and afferent pupillary defect, and a reduced amplitude of the P100 component of the visual evoked potential. Gd-DTPA leakage had ceased in 9/11 nerves when restudied 4 wks later, and this evolution was associated with improved visual acuity and an increased P100 amplitude. Leakage is likely to reflect inflammation, and we conclude that the latter plays an important part in the production of conduction block and clinical deficit, and that its resolution is an important step in clinical remission from acute episodes of demyelination.

Adolescent↗
PubMed1991

Potentials evoked in human and monkey cerebral cortex by stimulation of the median nerve. A review of scalp and intracranial recordings.

Somatosensory evoked potentials (SEPs) are generated in afferent pathways, subcortical structures and various regions of cerebellar and cerebral cortex by stimulation of somatic receptors or electrical stimulation of peripheral nerves. This review summarizes current knowledge of SEPs generated in cerebral cortex by stimulation of the median nerve, the most common form of stimulation for human research and clinical investigations. Major sources of data for the review are intracranial recordings obtained from patients during diagnostic or neurosurgical procedures, and similar recordings in monkeys. Short-latency cortical SEPs in the 20-40 ms latency range consist of P20 and N30, recorded from motor cortex and frontal scalp; P25 and N35, recorded from cortex near the central sulcus and central scalp; and N20 and P30, recorded from somatosensory cortex and parietal scalp. Several lines of evidence including cortical surface and intracerebral recordings, neuromagnetic recordings and lesion studies in humans and monkeys, strongly support the conclusion that these potentials are generated in contralateral somatosensory cortex in areas 3b and 1, in contrast to the conclusion of many previous studies that SEPs recorded from the frontal scalp are generated in motor cortex and other frontal lobe areas. These potentials are primarily mediated by cutaneous afferents of the dorsal column-medial lemniscal system; the contribution of muscle afferents has not been completely resolved but appears to be small. There is currently no evidence that short-latency SEPs are generated in cortex other than primary somatosensory cortex. Recordings from the vicinity of the second somatosensory area, from the supplementary motor and sensory areas and from surface cortex other than sensorimotor cortex have not detected reliable short-latency activity, although some of these regions generate long-latency potentials. Consequently, short-latency SEPs recorded from the scalp are similar to those recorded from the surface of sensorimotor cortex. Old World monkeys such as Macaca mulatta and M. fascicularis provide an excellent model for human short-latency SEPs. All the potentials described above in humans have corresponding monkey analogues, with similar distributions over the cortical surface. The squirrel monkey, a New World species, exhibits the same potentials, but due to the different morphology of sensorimotor cortex, the surface distribution of SEPs is quite different.

Afferent Pathways↗
PubMed1991

Spinal cord monitoring in scoliosis surgery. Experience with 1168 cases.

Since 1981, during operations for spinal deformity, we have routinely used electrophysiological monitoring of the spinal cord by the epidural measurement of somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial nerve. We present the results in 1168 consecutive cases. Decreases in SEP amplitude of more than 50% occurred in 119 patients, of whom 32 had clinically detectable neurological changes postoperatively. In 35 cases the SEP amplitude was rapidly restored, either spontaneously or by repositioning of the recording electrode; they had no postoperative neurological changes. One patient had delayed onset of postoperative symptoms referrable to nerve root lesions without evidence of spinal cord involvement, but there were no false negative cases of intra-operative spinal cord damage. In 52 patients persistent, significant, SEP changes were noted without clinically detectable neurological sequelae. None of the many cases which showed falls in SEP amplitude of less than 50% experienced neurological problems. Neuromuscular scoliosis, the use of sublaminar wires, the magnitude of SEP decrement, and a limited or absent intra-operative recovery of SEP amplitude were identified as factors which increased the risk of postoperative neurological deficit.

Adolescent↗
PubMed1991

Effects of trenbolone acetate on carcass characteristics and serum testosterone and cortisol concentrations in bulls and steers on different management and implant schemes.

The objective of this study was to determine the effects of different implanting schemes on serum testosterone and cortisol concentrations, and carcass traits of bulls and steers implanted with trenbolone acetate (TBA) and zeranol (Z). Twenty Polled Hereford bulls were randomly assigned to one of three treatments after birth. Five calves served as nonimplanted control bulls (NIB). Nine bulls were implanted (IB) with 140 mg of TBA and 36 mg of Z at about 1 mo of age and reimplanted with both compounds 10 wk later. When IB calves were about 21 wk of age, the TBA implant was removed and calves were reimplanted with Z every 10 wk until slaughter. Six calves were castrated at 3 wk of age and implanted (IS) with TBA and Z every 10 wk until slaughter. Blood samples from each animal were obtained at 14-d intervals beginning at 14 wk of age and serum cortisol (C) and testosterone (T) concentrations were determined. The NIB had higher C levels than IB or IS (P less than .05) during the preweaning period. During the finishing period, there were no differences in C concentrations between NIB and IB; however, IS had lower levels (P less than .05) than both bull treatments. Serum T concentrations began to increase about 12 wk later (42 vs 30 wk, respectively) in IB compared with NIB. Testicular size was smaller (P less than .05) in IB than in NIB. No differences (P greater than .05) were observed in carcass characteristics. Taste-panel scores were not different among treatments. In conclusion, implanting schemes using TBA and Z lowered serum levels of C and delayed puberty in bulls; however, they did not alter carcass characteristics or eating quality.

Anabolic Agents↗
PubMed1991

The effect of cimaterol and its withdrawal on carcass composition and meat tenderness of broiler chickens.

To examine the effects of cimaterol (CIM) and its withdrawal on meat tenderness and carcass composition, 21-d-old broiler chickens (n = 288) were randomly assigned to one of nine treatments. For Treatments 1 through 6, birds were fed a control diet or a diet containing 1 ppm CIM until slaughter at 35, 42, or 49 d of age. Treatments 7 and 8 consisted of birds fed the CIM diet for 14 d and then withdrawn from CIM for either 7 or 14 d before slaughter (42 or 49 d of age). In Treatment 9, birds were fed the CIM diet to 42 d of age, then withdrawn from CIM for 7 d. Breast muscle (BM) weight, leg muscle (LM) weight, whole body weight, and BM and LM cathepsin B and L activities were obtained on 12 birds/treatment. Body, LM and BM composition and BM shear values were obtained on 12 additional birds/treatment. Eight birds/treatment were used to balance the number of birds per pen. Leg muscle weight, as a percentage of whole body weight, was elevated in CIM-fed birds at all ages, and BM percentage was greater at 35 d of age (P less than .05). Leg muscle fat percentage was reduced at 35 and 42 d of age (P less than .05), and LM protein was elevated at 42 and 49 d of age (P less than .05) in CIM-fed birds. Percentage of protein in the BM of CIM-fed birds was elevated at 35 and 42 d of age. Protein content of the whole body was also increased at 35 d of age. Shear values were higher in 42- and 49-d-old CIM-fed birds.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1990

Parathyroid hormone, but not prostaglandin E2, changes the shape of osteoblasts maintained on bone in vitro.

Parietal bones from 2-week-old rats were dissected free from the sutural regions, dura mater, and periosteum, leaving the surface covered with osteoblasts and some osteoclasts. Prostaglandin (PG) production by these "stripped" bones under basal conditions and after exposure to parathyroid hormone (PTH) was measured by radioimmunoassay of the culture medium (minimum essential medium with or without added 10% heat-inactivated fetal calf serum). Cultured specimens were examined by scanning electron microscopy for changes in osteoblast length, orientation, ruffling, and overlap. As demonstrated previously, PTH caused the osteoblasts to elongate, align, and show fewer ruffles compared to controls. PTH increased PG synthesis by the stripped bones. Indomethacin inhibited PG formation but did not affect the osteoblast shape change. PGE2, indomethacin, or both drugs together had no discernible effect on any morphologic features. These findings indicate that PGE2 does not change osteoblast shape and that the cell shape change with PTH is not mediated by endogenous prostanoids.

Animals↗
PubMed1990

The effect of fluoride on the resorption of dentine by osteoclasts in vitro.

Osteoclasts were isolated mechanically from bones of prehatch chicks and cultured on dentine for 24 or 39 h in medium without or with added sodium fluoride at concentrations of 0.15, 1, 15, or 30 mg/liter. Fixed and toluidine blue-stained specimens were examined by light microscopy and osteoclasts were counted, all cells were removed and resorption pits were counted. The dentine was then prepared for scanning electron microscopy (SEM) and pits located on a raster search using backscattered electron imaging. Stereophotogrammetric measurements were made of the depths, plan and true surface areas and volumes of pits, and the volume:area ratio and a three-dimensional form factor calculated for each. The presence or absence of a ring of demineralization around each pit was recorded. Pits with the same plan area were significantly (p less than 0.001) less deep in cultures containing 15 or 30 mg/liter NaF and the incidence of rings around pits was higher (controls 2.7%, 15 mg/liter 31.3%, 30 mg/liter NaF 39.7%). In one experiment, pits were larger in the specimen cultured with added 1 mg/liter NaF, but in a much larger series of 631 (251 in the control and 380 in the 1 mg/liter NaF cultures) pits measured, depths, volumes and volume:plan-area ratios were significantly lower (p less than 0.001), and rings round pits 2.5 times more common, in the fluoride-treated group. A complex interplay of stimulation of some cells in the culture with indirect stimulation of osteoclasts and direct inhibition of osteoclastic resorptive function may be operating at this concentration of fluoride. In vivo, therapeutic doses of sodium fluoride would be expected to act not only to increase the formation of osteoid but also to suppress osteoclastic activity.

Animals↗