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Biomedical subjects

J R Morris

Publications and source records attributed to J R Morris.

At least 37 records · Page 2Linked to original sources
PubMed1997

The use of the Ilizarov technique in the correction of lower extremity deformities in children.

The first time the Ilizarov technique was used at Children's Hospital of Los Angeles, 25 limb segments were treated in 15 patients. Thirteen segments (52%) required angular correction, 6 (24%) required lengthening, and 6 (24%) required both angular correction and lengthening. Average angular correction was 21 degrees (8 degrees to 41 degrees); average length gained was 44 mm (25 to 85 mm). All patients except two achieved preoperative goals. A total of 17 minor (.68/limb) and four major (.16/limb) complications occurred in the 25 limb segments in the study. The total complication rate was .84 complications per limb segment. The most common complication was pin tract infection (11 patients). This comprised 52% of complications and occurred in 44% of limb segments.

Adolescent↗
PubMed1996

Magnetic resonance imaging of acute Maisonneuve fractures.

Magnetic resonance imaging (MRI) studies were performed on five patients with acute Maisonneuve fractures. All patients had sustained a twisting injury to their ankles and complained of ankle pain and pain over their proximal fibula. High quality images with excellent visualization of all the ankle ligamentous structures were obtained. MRI showed that the anterior inferior tibiofibular ligament was disrupted in all patients and the posterior inferior tibiofibular ligament was intact in three of five patients. Also, the anterior talofibular ligament was disrupted in all patients and the calcaneofibular ligament was ruptured in two of five patients. This raises the question of whether patients with Maisonneuve fractures have lateral ankle instability at long-term follow-up. Although the superficial deltoid ligament was disrupted in all patients, the deep deltoid ligament was intact in one patient, partially disrupted in one patient, and completely disrupted in three patients. The interosseous ligament was disrupted at the ankle in all patients, while the interosseous membrane was disrupted in the leg in all patients except one. This patient had an intact interosseous membrane despite rupture of the interosseous ligament at the ankle and the presence of a proximal one third fibula fracture.

Acute Disease↗
PubMed1995

Anterior-posterior stability in partially conforming condylar knee replacement.

The purpose of the study was to estimate the anterior-posterior displacements that would occur with total knee prosthetic designs of different sagittal radii under functional conditions. A key question was whether some designs provided excessive constraint. Patients who had different total knee prosthetic designs were tested in a special rig where the AP drawer was measured under loaded and unloaded conditions. These same designs of total knee prostheses were then tested in a rig under different conditions of compressive and shear loads. Using these experiments as verification, a theoretical treatment was developed to predict the AP displacement for different activities. It was concluded that designs with low to moderate conformity required soft tissue restraint under more strenuous activities, or where high shear forces occurred under low compressive loads. Designs of moderate to high conformity could be fully self-stabilizing under all realistic conditions. However, for all designs, the AP displacement was only a few millimeters under functional loads, indicating that special care must be taken during surgery to avoid conflict between the condylar surfaces and the retained cruciate ligaments so that restriction of motion and excessive wear do not occur.

Aged↗
PubMed1993

The behavior of gestating swine housed in the Hurnik-Morris system.

A group housing system for sows, the Hurnik-Morris (HM) system, was developed to address several of the perceived animal welfare limitations of existing housing methods. The HM system permits socially coordinated eating and resting, controlled and socially undisturbed feed intake, physical exercise, and regular exposure to boars. The HM system effectively uses and reinforces the behavioral phenomenon of the social synchronization of feeding and provides a less restrictive housing environment. The system provides housing for sows in small groups and an individual, non-competitive feeding environment using electronic feeding compartments. Gilts reared during gestation in the HM system were observed to spend less time lying in sternal recumbency (31 vs 21%; P = .004) and performing stereotypies (.10 vs .56%; P = .034) and to spend more time participating in social activities (1.4 vs .19%; P = .0007) than similar gilts kept in gestation crates (GC). The HM sows revealed a significantly longer latent period to postprandial lying than did GC gilts (64 vs 32 min; P = .0001). The order of gilt entry into the feeding compartments tended to be more consistent than the sequence of feeding compartments being entered (W = .57 vs .41; P = .06). This indicates that social factors seemed to be more important than spatial ones in determining the order of entry into the feeder compartments.

Aggression↗
PubMed1992

The performance of gilts in a new group housing system: endocrinological and immunological functions.

The effect of a new group housing system on performance (132 gilts and litters) and endocrinological (35 gilts) and immunological functions (28 gilts) was studied. Animals were randomly assigned to a conventional system (control), involving greater than 2 mo in individual stalls, or to the Hurnik-Morris (H-M) housing system, involving continuous housing in small groups, for breeding-gestating swine. The gilts were reared throughout gestation in their respective housing systems and moved 3 to 5 d prefarrowing to a common farrowing facility. Various production data were collected, including sow weight and backfat measurements, number of pigs born, number born alive, number weaned, litter birth weight, and litter weaning weight. An adrenal function test using dexamethasone pretreatment and ACTH1-24 challenge was imposed on gilts 5 d prebreeding and once between d 81 to 87 of gestation. Plasma progesterone was measured at the same time. Immune function was measured by serum antibody response to hen egg white lysozyme (HEWL) and delayed-type hypersensitivity (DTH) to tuberculin. Gilts reared in the H-M housing system exhibited a number of pigs weaned per litter and litter weaning weights comparable to the number and weights in the control system (7.3 +/- .33 vs 6.9 +/- .38, P = .421 and 56.9 +/- 2.42 kg vs 51.3 +/- 2.76 kg, P = .132, respectively). Prefarrowing and weaning backfat measurements were significantly reduced in group-housed gilts (15.8 +/- .45 mm vs 17.8 +/- .55 mm, P = .005 and 14.6 +/- .4 mm vs 16.2 +/- .42 mm, P = .008, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1990

Nonauditory injury threshold for repeated intense freefield impulse noise.

Exposure to impulse noise is an important occupational health concern. The risk of injury to auditory structures is well recognized and provides the cornerstone for present safety standards. For freefield impulse noise, nonauditory injury is dependent on peak pressure, positive phase duration (or impulse), and number of exposures. Trivial laryngeal petechiae are shown to precede nonauditory injury to more critical organs (ie, pulmonary and gastrointestinal systems). This study identifies the critical impulse noise thresholds causing trivial laryngeal petechial changes resulting from exposure to 5, 25, and 100 repetitions of specific levels of impulse noise. Because of anatomical differences, sheep should be slightly more susceptible to impulse noise laryngeal petechial changes than man; therefore, it seems reasonable to set the absolute limits for human occupational exposure levels below those causing laryngeal petechiae in sheep for persons wearing adequate hearing protection. This study does not address human auditory injury that may occur above or below these exposure limits even with proper hearing protection.

Accidents, Occupational↗
PubMed1987

Protection of cattle against heartwater in Botswana: comparative efficacy of different methods against natural and blood-derived challenges.

Five groups of Tswana-cross castrated male cattle between 20 and 30 months of age (a total of 158 animals) were transported from a ranch in a heartwater-free area of south Botswana to a feedlot near Gaborone in the east of Botswana where heartwater is endemic. On arrival, one group was vaccinated intravenously with the Onderstepoort sheep blood heartwater vaccine, one group was vaccinated intravenously with the new Onderstepoort tick-derived heartwater vaccine and a third group was vaccinated subcutaneously with this tick-derived vaccine. Vaccine reactions were blocked with long acting oxytetracycline on the first day of fever. A fourth group had a series of injections of long acting oxytetracycline on days 0, 7, 14 and 21 after arrival, and a fifth served as untreated controls. The animals remained at the feedlot for 65 days during which time they faced a low level of challenge by Amblyomma hebraeum ticks. None contracted heartwater and so they were then challenged, together with a further group of control cattle, with a dose of the sheep blood vaccine. Some animals in all groups had severe heartwater reactions and died despite therapy, but 76.7 per cent, 64.5 per cent and 74.3 per cent of the cattle in the blood vaccine, intravenous tick vaccine and long acting oxytetracycline groups respectively were resistant to challenge, compared with 48.3 per cent of the subcutaneous tick vaccine group and 36.4 per cent of the controls. It was concluded that intravenous vaccination of susceptible adult cattle with either the blood or the tick-derived vaccine needs careful monitoring in the month after vaccination and does not necessarily result in immune animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Carbon dioxide laser use in wound sealing and epikeratophakia.

This paper presents current clinical and experimental uses of the carbon dioxide laser and the results of our human and animal tissue fusion investigations. Trials were conducted with human scleral and corneal eye bank tissue and in albino rabbits. With power settings of 100 to 200 mW, optimal laser effect consisting of slight whitening and minimal edge shrinkage occurred between 10 and 70 mJ of total energy. No tissue adherence could be demonstrated with the parameters tested. A final study was made on the feasibility of sealing an epikeratophakia lenticle to its recipient bed using the carbon dioxide laser. The average force required to remove the button in the control experiments was 6.45 g and this increased to 6.99 g after laser treatment although no fusion was apparent. This was statistically significant (P less than .05).

Adhesiveness↗
PubMed1987

Tissue welding using a low energy microsurgical CO2 laser.

A low energy, CO2 laser adapted specifically for microsurgery can be used to assist in anastomosis by "welding" tissue through thermal coagulation. Which tissue constituents contribute to the bond are not known, and different constituents may be important in welding different organs.

Anastomosis, Surgical↗
PubMed1986

Laser-assisted microsurgical anastomosis.

A low power carbon dioxide laser was used to perform 212 end-to-end laser-assisted microvascular anastomoses (LAMA) of femoral arteries (mean diameter, 1.2 mm) in Sprague-Dawley rats. Eighty-two conventional microvascular suture anastomoses (CMSA) utilizing 10-0 monofilament interrupted sutures were done for comparison of techniques and wound healing. The mean duration of each anastomosis procedure was 16 minutes for the LAMA repairs, compared to an average of 27 minutes for the CMSA repairs (P less than 0.05). All anastomoses were patent at the completion of the procedure. Each laser-assisted anastomosis required an average of seven intermittent laser exposures of 0.1 to 0.3 seconds each with approximately 80 mW of CO2 (wavelength = 10.6 micron) radiation at a spot size of 150 micron. A patency rate of 95% was obtained on the LAMA vessels (202 of 212) compared to 96% for the CMSA repairs (79 of 82). A total of 14 aneurysms were noted in the LAMA group (7%) compared to 11 in the CMSA (13%). All aneurysms were in patent vessels. Histological analysis indicates that the progression of wound healing of LAMA and CMSA anastomoses follows similar paths chronologically and morphologically with increased scar tissue formation around the suture. Scanning electron microscopy confirms the comparable luminal healing of the LAMA and CMSA vessels, with complete reendothelialization occurring by 3 weeks postoperatively. The tensile strength of the LAMA repair, although low immediately after operation, is comparable to that of the intact artery at 21 days. These findings suggest that a low energy carbon dioxide microsurgical laser has potential beneficial clinical application for anastomosis of small vessels.

Animals↗
PubMed1985

Carbon dioxide laser stapedotomy. Thermal effects in the vestibule.

Small-fenestra stapedotomy has recently been popularized in efforts to reduce the incidence of sensorineural hearing loss following stapes surgery for otospongiosis. Lasers have been advocated as a tool to fenestrate the stapes footplate. Conversion of radiant energy from the laser into heat in the vestibule represents the greatest potential risk to the inner ear. Using a carbon dioxide laser with a focal point of 150 microns at 300 mm, fenestrations of the stapes footplate were performed in a series of 14 anesthetized cats. The laser power output ranged from 0.47 to 3.05 W, with pulse durations of 0.2 and 0.5 s. Resultant temperature elevations in the vestibule, measured by a thin-wire thermocouple, ranged from 0 to 4.4 degrees C (0 to 8 degrees F) and directly correlated to wattage and duration of the laser-beam pulse. Temperature changes could be reduced by use of lower wattage, shorter pulse duration, timed intervals between pulses, and convection cooling of the promontory.

Animals↗
PubMed1985

Laser-assisted microvascular anastomoses: angiographic and anatomopathologic studies on growing microvascular anastomoses: preliminary report.

A low-powered carbon dioxide laser was used to perform end-to-end anastomoses of growing femoral arteries (mean diameter 1.6 mm) in miniature swine. Five microvascular conventional anastomoses were performed with 10-0 monofilament interrupted sutures. Nine laser-assisted vascular anastomoses were performed. The mean duration of each anastomosis was 30 +/- 3 minutes for the conventional anastomosis and 20 +/- 2 minutes for the laser-assisted vascular anastomosis (p less than 0.05). All anastomoses were patent at the completion of the procedure. Each laser-assisted anastomosis required an average of eight laser pulses of 2 to 4 seconds. After 13 weeks the external diameters of the conventional anastomoses were 1.8 mm (+15%), while the laser-assisted anastomoses averaged 3.0 mm (+81%) (p less than 0.05). All nine laser-assisted anastomoses were patent, functional, and free of stenosis compared with one out of five conventional anastomoses. Histologically the laser induced minimal or no fibrosis, allowing normal physiologic healing and growth patterns. Electron microscopy confirmed that the integrity of the arterial layers had been restored. These findings suggest that a low-energy carbon dioxide laser has potential clinical application for anastomosis of small growing vessels.

Animals↗
PubMed1984

Monomer-polymer equilibria in the axon: direct measurement of tubulin and actin as polymer and monomer in axoplasm.

The monomer-polymer equilibria for tubulin and actin were analyzed for the cytoskeleton of the squid giant axon. Two methods were evaluated for measuring the concentrations of monomer, soluble (equilibrium) polymer, and stable polymer in extruded axoplasm. One method, the Kinetic Equilibration Paradigm ( KEP ), employs the basic principles of diffusion to distinguish freely diffusible monomer from proteins that are present in the form of polymer. The other method is pharmacological and employs either taxol or phalloidin to stabilize the microtubules and microfilaments, respectively. The results of the two methods agree and demonstrate that 22-36% of the tubulin and 41-47% of the actin are monomeric. The in vivo concentration of monomeric actin and tubulin were two to three times higher than the concentration required to polymerize these proteins in vitro, suggesting that assembly of these proteins is regulated by additional mechanisms in the axon. A significant fraction of the polymerized actin and tubulin in the axoplasm was stable microtubules and microfilaments, which suggests that the dissociation reaction is blocked at both ends of these polymers. These results are discussed in relationship to the axonal transport of the cytoskeleton and with regard to the ability of axons to change their shape in response to environmental stimuli.

Actins↗
PubMed1982

Stable polymers of the axonal cytoskeleton: the axoplasmic ghost.

We have examined the monomer-polymer equilibria which form the cytoskeletal polymers in squid axoplasm by extracting protein at low concentrations of monomer. The solution conditions inside the axon were matched as closely as possible by the extraction buffer (buffer P) to preserve the types of protein associations that occur in axoplasm. Upon extraction in buffer P, all of the neurofilament proteins in axoplasm remain polymerized as part of the stable neurofilament network. In contrast, most of the polymerized tubulin and actin in axoplasm is soluble although a fraction of these proteins also exists as a stable polymer. Thus, the axoplasmic cytoskeleton contains both stable polymers and soluble polymers. We propose that stable polymers, such as neurofilaments, conserve cytoskeletal organization because they tend to remain polymerized, whereas soluble polymers increase the plasticity of the cytoskeleton because they permit rapid and reversible changes in cytoskeletal organization.

Actins↗
PubMed1976

The sickness impact profile: conceptual formulation and methodology for the development of a health status measure.

The development of a health status measure, the Sickness Impact Profile (SIP), is described in terms of both its conceptualization and methodology. The need for a health status measure that is sensitive and appropriate, based on sickness-related behavior, and culturally unbiased, is discussed. A model of sickness behavior is presented as a guide for methodological development. The description of the initial developmental stage of the SIP includeds detailed discussion and documentation of the collection, sorting and grouping of items that comprise the SIP, scaling of the items, scoring of the instrument, and testing and revision of the prototype instrument. Results of preliminary tests of reliability, validity, and administrative feasibility are presented. Subsequent steps in revision and finalization, now under way, are outlined.

Attitude to Health↗