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Biomedical subjects

R Morris

Publications and source records attributed to R Morris.

At least 325 records · Page 18Linked to original sources
PubMed1988

Rheumatoid arthritis of the cervical spine: surface-coil MR imaging.

Fifteen patients with classic rheumatoid arthritis were investigated with plain films, pluridirectional tomography, and surface-coil T1-weighted MR imaging at 500/17 (TR/TE). We evaluated the atlantodental interval; basion-dental interval; density or intensity of the dens; dens erosion; cranial settling; anterior, posterior, lateral, or rotatory atlantoaxial subluxation; subaxial subluxation; ligamentous calcification or osteophytes; erosion; cystic changes; joint-space narrowing of the apophyseal articulations; and posterior spinous process erosion. In addition, the cervicomedullary angle and the neuraxis configuration were identified on MR images. To determine its normal range, the cervicomedullary angle was measured in 50 patients whose MR studies were unrelated to the craniovertebral junction. All patients with a cervicomedullary angle less than 135 degrees had evidence of brainstem compression, cervical myelopathy, or C2 root pain. Also, all patients with cervicomedullary junction compression were neurologically abnormal. MR was found to be as good as tomography in evaluating the atlantodental interval, dens erosion, ligamentous calcification or osteophytes of the upper spine, subaxial subluxation, and various subluxations that occur in the occiput-C2 area. MR was less effective than tomography in evaluating the basion-dental interval, erosion of the posterior spinous processes, apophyseal joint disease from C3 inferiorly, and cystic changes of the articular facets of C1-C2. The most clinically important parameters were well seen with MR. The data show that MR is an excellent imaging procedure for evaluating rheumatoid arthritis of the cervical spine.

Adult↗
PubMed1988

Myelinated axons in peripheral nerves of adult beagle dogs: morphometric and electrophysiological measurements.

The myelinated fibre composition and conduction velocities were measured for the ulnar, saphenous and caudal cutaneous sural nerves of 10 healthy beagle dogs. A systematic random sampling technique was used to estimate the fibre diameter frequency distributions and densities. Conduction velocities were measured from evoked compound nerve action potentials. All nerves showed bimodal diameter frequency distributions with modes being approximately the same for each nerve (2 to 4 microns and 8 to 10 microns or 10 to 12 microns). The variation in the average densities and in the shapes of histograms of the different nerves was slight; however, there was a wide variation for the same nerve in different individuals. The conduction velocities for the fastest conducting axons in the nerves ranged from 63 to 79 m s-1. These normal quantitative processes affecting peripheral nerves in the dog.

Action Potentials↗
PubMed1987

Ectopic expression of Thy-1 in the kidneys of transgenic mice induces functional and proliferative abnormalities.

Hybrid human--mouse Thy-1.1 genes were injected into pronuclei of Thy-1.2 mice to produce transgenic animals. A hybrid gene composed of the 5' part of the mouse Thy-1.1 gene combined with the 3' human untranslated regions was expressed abnormally in the kidney podocytes, which resulted in severe protein-uria and subsequent death in several founder mice. A hybrid Thy-1 gene composed of the human coding region with the 5' and 3' flanking regions of the mouse gene was expressed abnormally in a different part of the kidney (the tubular epithelia), which resulted in a proliferative kidney disorder. In addition, a neoplasm was found in the brain of one of these mice. These results show that the Thy-1 protein can play an important role in the activation, proliferation, and differentiation of many different cell types.

Animals↗
PubMed1987

Innervation of facial skin but not masticatory muscles or the tongue by trigeminal primary afferents containing somatostatin in the rat.

Using retrograde transport of a fluorescent dye, True blue, the peripheral tissues innervated by trigeminal ganglion neurones containing somatostatin have been investigated. Of ganglion neurones retrogradely labelled from injections of dye into the facial skin, 3.45% were found to be immunoreactive for somatostatin. In contrast, none of the neurones labelled from injections of dye into the tongue or masseter muscle were found to contain this peptide. This demonstration of a restricted distribution of somatostatin-containing primary afferents raises the possibility that somatostatin may be involved in functions which are specific to skin and not to the other tissues examined.

Animals↗
PubMed1987

Responses of neurones in the brainstem raphe nuclei to stimulation of the cerebellar fastigial nuclei in the cat.

Stimulation of the fastigial nuclei of the cerebellum was found to excite units located throughout the raphe nuclei of the brainstem. Raphe spinal units with axons conducting at velocities below 20 m/s were either unaffected by fastigial nucleus stimulation or inconsistently excited at long latency. In contrast units with faster conducting spinal axons throughout the raphe and more dorsally in the reticular formation were excited by stimulation of the fastigial nuclei. Many of these units responded at short latency and followed high rates of repetitive stimulation.

Action Potentials↗
PubMed1987

Inhibition of nociceptive responses of laminae V-VII dorsal horn neurones by stimulation of mixed and muscle nerves, in the cat.

Low frequency (1-3 Hz) stimulation of muscle nerves (ipsilateral medial and lateral gastrocnemius nerves) had to be applied at intensities which would recruit C-fibre afferents, to produce inhibition of nociceptive responses of cat lumbar spinal cord laminae V-VII units. Inhibitory responses evoked by muscle nerve stimulation and also by mixed nerve stimulation could be blocked by microionophoretically applied bicuculline. No effects on these inhibitions were obtained with naloxone.

Animals↗
PubMed1987

Hypoxemia during ambulatory gynecologic surgery as evaluated by the pulse oximeter.

Pulse oximetry was used to determine the incidence of intraoperative hypoxemia in 108 patients undergoing ambulatory gynecologic operation. Eleven (10%) experienced moderate desaturation (arterial oxygen saturation less than 90%), and 5 (5%) suffered severe hypoxemic episodes (arterial oxygen saturation less than 85%). Among patient risk factors--including operation, body habitus, smoking habits, history of asthma, age, and airway characteristics--an association with moderate hypoxemia was found only with nonlaparoscopic gynecologic operation, obesity, and age over 35 years, and an association with severe hypoxemia was found only with obesity and age over 35. Among operative events--including inspired oxygen concentration, position, mode of ventilation, and anesthesia phase--an association with moderate hypoxemia was found only with the lithotomy position, manual ventilation, and arousal. The cost per patient of monitoring with a pulse oximeter is about +1.35. A cost-benefit analysis reveals that a mortality rate of 1 in 40,000 among patients who actually become moderately hypoxemic would justify the cost of monitoring arterial oxygen saturation. We conclude that pulse oximetry should be part of routine anesthetic monitoring.

Adult↗
PubMed1987

Techniques for comparison of thermal and mechanical nociceptive stimuli in the sheep.

The assessment of analgesia in conscious unrestrained farm animals presents particular problems. In order to provide a reliable nociceptive stimulus, two devices have been constructed, one that provides a threshold reading for a ramped thermal stimulus of the pinna of the ear and another that measures a threshold reading for a pressure stimulus to the foreleg. Both devices allow the rapid termination of the stimulus once a reaction has occurred and allow repeated readings without causing tissue damage. Examples of the analgesic action of alpha 2-adrenoceptor agonists and opioids measured by using the two pieces of apparatus are shown.

Animals↗
PubMed1987

Differential regulation of a Thy-1 gene in transgenic mice.

We have generated Thy-1.1-transgenic Thy-1.2 mice to study the developmental expression of the Thy-1 gene in detail by transcriptional and immunological methods. In brain, the expression of the injected gene was identical to that of the endogenous gene in a tissue- and development-specific manner. In lymphoid tissue, the transferred gene was also expressed correctly in the early phases of T-cell lineage development; however, as the T cells matured, the transcription of the transferred gene, but not the endogenous gene, was suppressed. This result shows that different regulatory elements are used to express the Thy-1 gene in early and late lymphoid development.

Age Factors↗
PubMed1987

Reproductive characteristics of spontaneous single and double ovulating mares and superovulated mares.

For embryos collected from mares 7 days after ovulation, embryo recovery for single-ovulating mares was 53% compared to 106% for double-ovulating mares. Pregnancy rates 50 days after surgical transfer were 68 and 129%, respectively. Concentrations of LH were similar during the periovulatory period for cycles which included single or double ovulations. Horse pituitary extract given for 5.5 days resulted in greater than or equal to 2 ovulations (mean 3.8) in 26 of 28 mares and 2.0 embryos were recovered per donor compared to 0.65 for controls. Non-surgical pregnancy rates for embryos collected from superovulated mares 6 and 8 days after ovulation (18 of 46; 39%) were identical to those obtained for untreated controls (12 of 31; 39%). The overall pregnancy rate for superovulated donors, which provided 2-4 embryos, was 120%. Since the viability of multiple embryos collected from spontaneous and induced multiple-ovulating mares was equal to that of embryos from single-ovulating mares, collection and transfer of embryos from these mares will increase the efficiency of horse embryo transfer.

Animals↗