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Biomedical subjects

J R Morris

Publications and source records attributed to J R Morris.

At least 19 recordsLinked to original sources
PubMed1999

Core promoter elements can regulate transcription on a separate chromosome in trans.

Transvection can cause the expression of a gene to be sensitive to the proximity of a homolog. It can account for many cases of intragenic complementation at the Drosophila yellow gene, where one mode of transvection involves the action of enhancers in trans on a promoter present on a separate chromosome. Our goal was to identify cis-acting elements that regulate the trans action of enhancers. Using gene replacement, we altered two core promoter elements at yellow and tested the resulting alleles for their ability to support transvection. We found that the TATA box and initiator element can regulate transvection.

Drosophila Proteins↗
PubMed1999

Transvection and other homology effects.

The presence of homologous nucleic acid sequences can exert profound effects on chromosomal and gene function in a wide range of organisms. These homology effects reveal remarkable forms of regulation as well as suggest possible avenues for the development of new technologies.

DNA Methylation↗
PubMed1999

An analysis of transvection at the yellow locus of Drosophila melanogaster.

Studies of a wide variety of organisms have shown that homologous sequences can exert a significant impact on each other, resulting in changes in gene sequence, gene expression, chromatin structure, and global chromosome architecture. Our work has focused on transvection, a process that can cause genes to be sensitive to the proximity of a homologue. Transvection is seen at the yellow gene of Drosophila, where it mediates numerous cases of intragenic complementation. In this article, we describe two approaches that have characterized the process of transvection at yellow. The first entailed a screen for mutations that support intragenic complementation at yellow. The second involved the analysis of 53 yellow alleles, obtained from a variety of sources, with respect to complementation, molecular structure, and transcriptional competence. Our data suggest two ways in which transvection may be regulated at yellow: (1) a transcriptional mechanism, whereby the ability of an allele to support transvection is influenced by its transcriptional competency, and (2) a structural mechanism, whereby the pairing of structurally dissimilar homologues results in conformational changes that affect gene expression.

Alleles↗
PubMed1998

Two modes of transvection: enhancer action in trans and bypass of a chromatin insulator in cis.

Ed Lewis introduced the term "transvection" in 1954 to describe mechanisms that can cause the expression of a gene to be sensitive to the proximity of its homologue. Transvection since has been reported at an increasing number of loci in Drosophila, where homologous chromosomes are paired in somatic tissues, as well as at loci in other organisms. At the Drosophila yellow gene, transvection can explain intragenic complementation involving the yellow2 allele (y2). Here, transvection was proposed to occur by enhancers of one allele acting in trans on the promoter of a paired homologue. In this report, we describe two yellow alleles that strengthen this model and reveal an unexpected, second mechanism for transvection. Data suggest that, in addition to enhancer action in trans, transvection can occur by enhancer bypass of a chromatin insulator in cis. We propose that bypass results from the topology of paired genes. Finally, transvection at yellow can occur in genotypes not involving y2, implying that it is a feature of yellow itself and not an attribute of one particular allele.

Animals↗
PubMed1998

Expression patterns of the human papillomavirus type 16 transcription factor E2 in low- and high-grade cervical intraepithelial neoplasia.

Specific antibodies against the C-terminus of E2, produced by affinity purification of polyclonal antisera, have been used to identify the cellular populations which express the HPV 16 E2 transcription factor, in a series of formalin-fixed, paraffin-embedded cervical tissues. Cases were selected for both the presence of HPV 16 DNA (confirmed by multiple gene-specific PCR detections) and the presence of multiple grades of cervical intraepithelial neoplasia (CIN). The data indicate that E2 expression is highest in CIN I and in koilocytic lesions. Lower expression was observed in CIN II and little in CIN III lesions. In contrast, there was some restoration of E2 expression in invasive carcinomas, although the intracellular distribution was much more diffuse. The location of E2 expression to the superficial layers of the cervical epithelium, as well as the occurrence of some basal expression in CIN I, suggests that antibodies against HPV 16 E2 could be a useful adjunct to standard histological techniques for the detection of 'at-risk' patients as part of a cervical screening programme.

DNA-Binding Proteins↗
PubMed1998

The effect of the Hurnik-Morris (HM) system on sow reproduction, attrition, and longevity.

Sows were randomly selected and assigned to either the Hurnik-Morris system (HM; n = 59) or a conventional gestation crate system (GC; n = 90) before breeding. The HM system provides housing for sows in small groups. All sows were bred to Duroc x Hampshire commercial boars. A common farrowing barn with 18 farrowing crates was used for the HM and GC sows. The HM sows had less (P<.001) backfat at farrowing. Average parity per sow (P<.046), lifetime number of pigs born per sow (P<.02), lifetime number of pigs born alive per sow (P<.02), and lifetime number weaned per sow (P<.045) were higher for sows housed in the HM system. The total number of sows removed from the GC system was higher (P<.025) than the number leaving the HM system. The higher parity level and lifetime production exhibited by the sows in the HM system indicates that this system supports greater longevity and may reflect the superior effect that this housing system has on animal well-being.

Animals↗
PubMed1997

Quantitative description of analyte migration behavior based on dynamic complexation in capillary electrophoresis with one or more additives.

A comprehensive theory is proposed to describe the migration behavior of analytes in capillary electrophoresis (CE) when one or more additives are present in the buffer solution. This theory amalgamates and extends the previous work done by others. The capacity factor (k') in this theory is defined as the product of the equilibrium constant and the additive concentration, thus, k' changes linearly with additive concentration. The net electrophoretic mobility of an analyte is a function of k', therefore, it can be changed by varying the additive concentration. Three parameters are needed to predict the mobility of an analyte in a one-additive CE system: the mobility of the free analyte, the mobility of the complex, and the equilibrium constant for the analyte-additive interaction (which determines the fraction of the free analyte at different additive concentrations). When additives are used, the change in viscosity obscures this relationship, therefore, a viscosity correction factor is required to convert all mobilities to an ideal state where the viscosity remains constant. The migration behavior of an analyte in a solution with multiple additives can be predicted and controlled, once the equilibrium constants of the interactions between the analyte and each of the additives are obtained separately. beta-Cyclodextrin and hydroxypropyl-beta-cyclodextrin are used as additives and the migration behavior of phenol, p-nitrophenol, and benzoic acid are studied as a model system to verify this theory. When the necessary viscosity correction factor is included, the net electrophoretic mobilities of the analytes obtained from experimental results agree with the values predicted by the theory based on dynamic complexation. Although only experiments with one and two additives were carried out to verify the theory, the equations apply to situations when more than two additives are used. The relationship between the theories of electrophoresis and chromatography is clarified.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1997

Cardiopulmonary effects of high-impulse noise exposure.

In high-energy impulse noise environments, the biomechanical coupling process between the external forces and the pathophysiology of cardiopulmonary injury is not well understood. A 12-in-diameter compressed air-driven shock tube with reflector plate was used to induce three levels of pulmonary contusion injury in a large animal model. Twenty-one anesthetized sheep were exposed to the various levels of impulse noise generated by the shock tube, with six additional sheep serving as a control group. Pathologic evaluations, performed 3 hours after exposure, showed pulmonary contusion ranging from minor petechial changes on the surface of the lung parenchyma to diffuse ecchymoses affecting as much as 60% of the lung. The gross pathologic observations of injury produced by exposure to the impulse noise produced by the shock tube were similar to those reported for blunt impact trauma or exposure to chemical or grain-dust explosions. The extent of lung injury (lung injury index) was quantitatively assessed. A semilogarithmic relationship between the lung injury index and the measured peak pressure was demonstrated. A significant linear correlation was demonstrated between lung injury index and lung weight-to-body weight ratio. Significant cardiopulmonary changes were also observed as a result of exposure to high-impulse noise. Although in most cases the degree of change was related to the severity of the injury, significant cardiopulmonary function changes were also observed in the absence of significant grossly observable pulmonary injury. Cardiac injury was indicated by decreased cardiac output and hypotension at all levels of injury and might be the result of myocardial contusion or air emboli. Pulmonary injury was demonstrated by respiratory acidosis, increases in lung resistance, and decreases in lung compliance and lung volume. Arterial PO2 appeared to be the most sensitive parameter of injury and was decreased for all measurement intervals for all exposure groups.

Animals↗
PubMed1997

The effect of the Hurnik-Morris (HM) system on sow locomotion, skin integrity, and litter health.

Gilts (n = 187) were randomly assigned to either the Hurnik-Morris housing system (HM) or a conventional gestation crate system (GC) prior to breeding. The Hurnik-Morris system provides housing for sows in small groups. Gilts were synchronized for estrus and bred to Duroc Hampshire commercial crossbred boars. Gilts were reared in their respective housing systems through their gestation period. Housing system during breeding and gestation of sows did not affect their respective piglet mortality and piglet viability levels. The slightly higher feet and leg problem scores for the HM sows at weaning may indicate a necessity for farrowing accommodation that will allow movement of sows during lactation.

Animals↗
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↗