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Biomedical subjects

J C Morrison

Publications and source records attributed to J C Morrison.

At least 19 recordsLinked to original sources
PubMed2001

Changes in Thy1 gene expression associated with damaged retinal ganglion cells.

PURPOSE: The temporal series of molecular events that occur in dying retinal ganglion cells is poorly understood. We have examined the change in expression of a normally-expressed ganglion cell marker gene, Thy1, relative to the kinetics of cell loss caused by acute and chronic damaging stimuli. METHODS: For acute experiments, mice were subjected to optic nerve crush or intravitreal injections of N-methyl-D-aspartate (NMDA) to induce ganglion cell death. RNase protection analysis was used to quantify Thy1 mRNA levels from total retina RNA and in situ hybridization was used to monitor the pattern of Thy1 positive cells. Changes in Thy1 expression were compared to the time course of cell loss induced by each treatment. To induce elevated intraocular pressure (IOP), the episcleral veins of rats were injected with hypertonic saline, which scleroses Schlemm's Canal and the trabecular meshwork. Elevated IOP was monitored every day for 35 days after which the animals were sacrificed and the retinas harvested for quantitative RT-PCR or fixed for in situ hybridization studies. Evaluation of glaucomatous damage caused by elevated IOP was determined from histological sections of the optic nerves of all rat eyes. RESULTS: After optic nerve crush, Thy1 mRNA levels decreased within 24 h, although the number of expressing cells did not decline until 7 days. Both measures showed a loss of Thy1 well in advance of cell loss, which was detected by 2 weeks after surgery. This change in expression was not dependent on execution of the cell death program since a similar decrease was detected in Bax-/- ganglion cells, which are resistant to cell death induced by optic nerve crush. Thy1 mRNA levels and the number of expressing cells also decreased within 6 h after NMDA injection, in advance of cell loss, which was detected by 24 h. Similarly, elevated intraocular pressure was associated with a decrease in mRNA and expressing cells in a pressure-dependent manner. In moderately hypertensive rat eyes, the number of cells expressing Thy1 decreased before significant cell loss in the retina. Virtually no Thy1-expressing cells were detected in eyes with severe disease. CONCLUSIONS: Thy1 mRNA abundance and expressing cells, decreased in advance of detectable ganglion cell loss caused by three different modalities of damage. This change is independent of the committed step of cell death.

Animals↗
PubMed2001

A Canadian faculty of medicine and dentistry's survey of career development needs.

INTRODUCTION: Career development efforts for adult learners are more likely to succeed if they are responsive to the learners' needs, offered at convenient times, and provided in a variety of forms. METHODS: The Faculty of Medicine and Dentistry at the University of Alberta conducted a self-administered career development needs survey of full-time academic faculty. Faculty members were asked to identify how useful each of 35 career development skills would be to them and at which stage in an academic career it would be most useful. Preferred educational modes and times of delivery were also assessed. The mean rankings of skill needs were examined overall as well as by gender, academic rank, departmental category (clinician versus basic scientist), marital status, and the presence of school-aged children at home. RESULTS: 185 of 446 (41%) mailings were returned, of which 181 were evaluated. The number one perceived career development need across all subgroups was 'Effective writing of grants and publications'. Six of the top 10 needs were identified as useful at all career stages. Significant differences in rankings of needs were noted between subgroups. Half days were preferred to full days for career development efforts and short courses to other educational modes. DISCUSSION: Several career development skills were identified as priorities independently of gender, academic rank, and clinical versus basic science career tracks. Differences suggest that within a basic global programme, a variety of career development modules may need to be developed for subgroups.

Alberta↗
PubMed2001

Pregnancy outcome in women with preterm labor symptoms without cervical change.

OBJECTIVE: This study was undertaken to determine pregnancy outcome in women who have preterm labor symptoms without cervical change according to fetal fibronectin status. STUDY DESIGN: Patients who were examined at the obstetric emergency department with symptoms of preterm labor but without cervical change underwent fetal fibronectin collection. Pregnancy outcome and fetal fibronectin results were analyzed after delivery. RESULTS: Of the 235 patients sampled, 20% (n = 48) had positive fetal fibronectin results. The mean +/- SD gestational age at delivery was lower in women with positive fetal fibronectin results (34.2 +/- 4.1 vs 37.7 +/- 2.3 weeks; P <.001); these women were more likely to deliver preterm as a result of preterm labor than women with other obstetric indications (46% vs 19%; P <.001). Infants born to these women demonstrated lower birth weight (2317 +/- 895 g vs 2877 +/- 557 g; P =.003), were more likely to be admitted to the neonatal intensive care unit (42% vs 14%; P <.001), and were more likely to die in the neonatal period (11% vs 0%; P <.001). CONCLUSION: Patients with symptoms of preterm labor but without cervical change who have negative fetal fibronectin results are less likely to deliver preterm. Therefore in women with symptoms but without cervical change fetal fibronectin should be considered for risk assessment.

Adult↗
PubMed2001

Does uterine wiping influence the rate of post-Cesarean endometritis?

OBJECTIVE: To compare two methods of uterine cleansing to remove residual amnion-chorion at the time of Cesarean delivery. METHODS: All consenting uninfected parturients undergoing a non-emergency Cesarean delivery at the university were enrolled. All patients received antibiotic prophylaxis of a 1-g intravenous bolus of a first-generation cephalosporin immediately after cord clamping. Postpartum endometritis was defined as a temperature of > or = 100.4 degrees F (38 degrees C) on two occasions 6 h apart after the first 24 h with uterine tenderness and/or foul-smelling lochia. RESULTS: Between January 1998 and February 2000 there were 1400 patients enrolled in this investigation. A total of 153 women were determined to have chorioamnionitis present at surgery and 17 women refused participation, leaving 614 women in the uterine wipe group and 616 in the no wipe group. Maternal demographics were similar between patient groups (NS). Intrapartum factors including gestational age at time of Cesarean section, type of anesthesia used for the operative delivery, hours of amnion rupture prior to delivery, use of internal monitoring devices, type of skin incision, method of placental removal, total operative time and estimated blood loss were similar between patient groups (NS). An almost identical number of patients in each arm of the study developed post-Cesarean endometritis (65 out of 614, 10.5%, in the uterine wipe group vs. 66 out of 616, 10.7%, in the no wipe group; p = 1). CONCLUSIONS: Both methods of removing residual amnion-chorion membrane tissue and associated debris at surgery were comparably effective, but neither produced a dramatic reduction in the incidence of postoperative endometritis.

Adult↗
PubMed2001

Subjective versus objective evaluation of amniotic fluid volume of pregnancies of less than 24 weeks' gestation: how can we be accurate?

This study was undertaken to compare subjective versus objective ultrasonic evaluation of amniotic fluid volume in pregnancies of less than 24 weeks' gestation. Amniotic fluid volume was subjectively (visualization without ultrasonic measurements) and objectively (visual interpretation with ultrasonic measurements) evaluated in 42 singleton pregnancies undergoing termination. The actual amniotic fluid volume was then determined using a dye-dilution technique. The women evaluated were in their mid-20s, primarily African American, and between 15 and 23 weeks' gestation. There was no significant difference in the total number of correct estimates of amniotic fluid volume when the data were stratified by level of operator experience (P = .34), ultrasonic technique (P = .33), or the combined correct subjective versus combined correct objective estimates (P = .68). We have concluded that the accuracy of amniotic fluid volume assessment in pregnancies of less than 24 weeks is not influenced by the level of operator experience or the type of ultrasonic measurement.

Amniotic Fluid↗
PubMed2001

Maternal morbidity and mortality associated with intrauterine fetal demise: five-year experience in a tertiary referral hospital.

BACKGROUND: Risk factors for and management of intrauterine fetal demise (IUFD) have been investigated, but the maternal morbidity has not been evaluated. METHODS: Over a 60-month interval, all cases of IUFD after 20 weeks' gestation were reviewed for maternal trauma and maternal postpartum complications. RESULTS: In this retrospective analysis, 498 singleton and 24 twin pregnancies with an IUFD were identified. A cervical or perineal laceration requiring surgical repair complicated 9.4% of pregnancies. One uterine dehiscence and one uterine rupture occurred. Endometritis, the most common postpartum complication, occurred in 63 of 522 patients (12%). One maternal death occurred. Total mean hospital stay was 4.9 +/- 5.7 days. CONCLUSION: Maternal morbidity and rarely mortality can follow IUFD, but this morbidity is similar to that observed without IUFD.

Adult↗
PubMed2001

Labor and membrane rupture in twin gestation. Can they affect the ability to estimate fetal weight?

OBJECTIVE: To determine whether labor or fetal membrane rupture adversely affects the ability of ultrasound to accurately estimate fetal weight (EFW) in a twin gestation. STUDY DESIGN: A medical record audit was performed of the two-year experience of women delivering live born twins and undergoing a complete ultrasound examination within 72 hours of delivery. Those patients experiencing labor or membrane rupture at the time of the previous ultrasound examination were compared to those without these factors to determine if there was any detrimental impact on the accuracy of ultrasound to EFW. RESULTS: The overall ability of ultrasound to accurately EFW was in the range of 64-76%. This was not significantly different from the accuracy in women experiencing labor (62-80%) or in women with membrane rupture (63-81%). The ability of ultrasound to detect fetal discordance is this series ranged from 78% to 100%, with specificity that ranged from 84% to 89%. CONCLUSION: The ability of sonography to accurately EFW as well as detect discordant twin gestation is not altered by the presence of labor or membrane rupture.

Adult↗
PubMed2000

The effects of physical abuse on pregnancy outcomes in a low-risk obstetric population.

OBJECTIVE: This study was undertaken to evaluate the impact of physical abuse on pregnancy outcomes. STUDY DESIGN: This prospective investigation identified all women seen in the outpatient obstetric clinic with a history of physical abuse and matched each with the next 2 women seen without a history of physical abuse (case/control ratio, 1:2). RESULTS: Twenty-eight abused women were matched with 56 control subjects. The frequencies of preterm birth, mode of delivery, Apgar scores <7 at 5 minutes, umbilical artery pH <7.10 at birth, and unhappy or ambivalent feelings about the pregnancy were not statistically different between the 2 groups. Admission to the neonatal intensive care unit was more common among infants of the abused women (n = 4 [14.2%] vs n = 2 [3.6%]), despite heavier birth weights in the abused group (3501 +/- 581 g vs 3200 +/- 549 g; P =. 023), but this trend did not reach significance. CONCLUSION: A history of physical abuse did not result in adverse pregnancy outcomes, although neonatal intensive care unit admission was more likely.

Adult↗
PubMed2000

A prospective, randomized, controlled trial of high and low maintenance doses of magnesium sulfate for acute tocolysis.

OBJECTIVE: This study was undertaken to compare a high-dose protocol for magnesium sulfate tocolytic therapy with a low-dose regimen with respect to time needed to achieve tocolysis. STUDY DESIGN: Patients between 24 and 34 weeks' gestation with preterm labor were included. Patients with ruptured membranes or nonreassuring fetal assessments were excluded. Gravid women received a 4-g loading dose of magnesium sulfate and were prospectively randomly assigned to receive a maintenance dose of 2 or 5 g/h. RESULTS: The median times to tocolysis were 120 minutes (semi-interquartile range, 30 minutes) in the low-dose group and 90 minutes (semi-interquartile range, 28 minutes) in the high-dose group (P <.001). CONCLUSION: Patients treated with a higher maintenance dose of magnesium sulfate had a higher frequency of side effects; however, tocolysis was achieved more rapidly and they required shorter admissions to the labor and delivery unit without increased maternal or neonatal morbidity.

Adult↗
PubMed2000

Determination of amniotic fluid volume in twin pregnancies: ultrasonographic evaluation versus operator estimation.

OBJECTIVE: We sought to determine the accuracy of amniotic fluid volume estimation (visually) in diamniotic twin pregnancy versus ultrasonography techniques. STUDY DESIGN: In this prospective study the volume of each sac in 23 sets of diamniotic twin pregnancies was subjectively and objectively estimated by a second-year obstetric resident, nurse sonographer, maternal-fetal medicine fellow, and maternal-fetal medicine staff. The actual volume was confirmed by amniocentesis and a dye-dilution technique. RESULTS: There was no difference in the total number of correct estimates of volume by level of operator experience (P =.98), ultrasonography technique (P =.87), or combined subjective versus objective correct estimates (P =.87). Identification of low volume was not different among the four evaluators (P =.48), but the percentage of correct estimates was poor (7%-29%). The 2-diameter pocket was a better predictor of oligohydramnios (57%) than the amniotic fluid index or the largest vertical pocket (12.5%; P =.002). CONCLUSION: The extremes of volume (low or high) are poorly identified by the subjective or objective assessment of volume.

Adult↗
PubMed2000

Chronology of optic nerve head and retinal responses to elevated intraocular pressure.

PURPOSE: To determine the chronology of optic nerve head and retinal responses to elevated intraocular pressure (IOP). METHODS: After 1 to 39 days of unilaterally elevated IOP, experimental and fellow rat eyes were examined for morphology and immunohistochemical labeling alterations and for ganglion cell DNA fragmentation. RESULTS: Mean IOP for the experimental eyes was 36 +/- 8 mm Hg, an approximately 15-mm Hg elevation above normal values. By 7 days of pressure elevation above 40 mm Hg, endogenous immunostaining for brain-derived neurotrophic factor and neurotrophin 4/5 was absent from the nerve head and superior retina, whereas normal labeling was present in the inferior retina and distal optic nerve of these same eyes. These changes were preceded by a loss of gap junctional connexin43 labeling and astrocytic proliferation in the nerve head and by increased retinal ganglion cell layer apoptosis in the retina. Nerve head depletion of neurotrophins coincided with evidence of axonal degeneration, loss of astrocytic glial fibrillary acidic protein staining, and spread of collagen VI vascular immunolabeling. After longer durations at these same pressures, neurotrophin labeling returned to nerve head glia and scattered retinal ganglion cells. CONCLUSIONS: Optic nerve head and retinal responses, including the depletion of endogenous neurotrophins, are readily identified in the rat eye after experimental IOP elevation. However, the apparent chronology of these responses suggests that the withdrawal of neurotrophic support was not the only determinant of retinal ganglion cell apoptosis and axonal degeneration in response to pressure.

Animals↗
PubMed2000

Sonographic measurements of fetal parts to predict pulmonary maturity among twins and singletons.

To determine if sonographic examination of fetus can be readily utilized to predict a mature lecithin/sphingomyelin (L/S) ratio among twins and singletons. Twins (n = 36) undergoing amniocentesis for assessment of pulmonary maturity were matched with singleton (1:2) for maternal demographics, gestational age (GA), and indications for procedure. At the time of amniocentesis, twins and singletons with mature L/S ratios differed significantly in mean GA (33.2 +/- 2.7 vs 34.5 +/- 4.6 wks, p = 0.01), biparietal diameter (BPD), abdominal circumference (AC), femur length (FL) and estimate of birth weight (EFW). Based on ten receiver operating characteristics curves constructed, the following diagnostic thresholds predicted a mature L/S ratio with a true positive rate of 100% among twins and singletons, respectively: 1) BPD $84 and $92 mm; 2) head circumference $315 and $320 mm; 3) AC $295 and $350 mm; or 4) FL $64 and $72 mm; or 5) EFW $2400 and $3200 g. Using any one of these five criteria correctly identified pulmonary maturity among 59% of twins and 28% of singletons (p = 0.001). Sonographic measurement of fetal parts or EFW may be a noninvasive method to predict a mature L/S ration among twins as well as singletons.

Adult↗
PubMed2000

Patterns of intraocular pressure elevation after aqueous humor outflow obstruction in rats.

PURPOSE: To determine the diural intraocular pressure (IOP) response of Brown Norway rat eyes after sclerosis of the aqueous humor outflow pathways and its relationship to optic nerve damage. METHODS: Hypertonic saline was injected into a single episcleral vein in 17 animals and awake IOP measured in both the light and dark phases of the circadian cycle for 34 days. Mean IOP for light and dark phases during the experimental period were compared with the respective pressures of the uninjected fellow eyes. Optic nerve cross sections from each nerve were graded for injury by five independent masked observers. RESULTS: For fellow eyes, mean light- and dark-phase IOP was 21 +/- 1 and 31 +/- 1 mm Hg, respectively. For four experimental eyes, mean IOPs for both phases were not altered. Six eyes demonstrated significant mean IOP elevations only during the dark phase. Of these, five showed persistent, large circadian oscillations, and four had partial optic nerve lesions. The remaining seven eyes experienced significant IOP elevations during both phases, and all had extensive optic nerve damage. CONCLUSIONS: Episcleral vein injection of hypertonic saline is more likely to increase IOP during the dark phase than the light. This is consistent with aqueous outflow obstruction superimposed on a circadian rhythm of aqueous humor production. Because these periodic IOP elevations produced optic nerve lesions, both light- and dark-phase IOP determinations are necessary for accurate correlation of IOP history to optic nerve damage in animals housed in a light- dark environment.

Animals↗
PubMed2000

Effect of general anesthetics on IOP in rats with experimental aqueous outflow obstruction.

PURPOSE: To determine the effect of several common general anesthetics on intraocular pressure (IOP) after experimental aqueous outflow obstruction in the rat. METHODS: A single episcleral vein injection of hypertonic saline was used to sclerose aqueous humor outflow pathways and produce elevated IOP in Brown Norway rats. Animals were housed in either standard lighting or a constant low-level light environment. Awake IOPs were determined using a TonoPen (Mentor, Norwell, MA) immediately before induction of anesthesia by either isoflurane, ketamine, or a mixture of injectable anesthetics (xylazine, ketamine, and acepromazine). For each anesthetic, IOPs were measured immediately after adequate sedation (time 0) and at 5-minute intervals, up to 20 minutes. RESULTS; Awake IOPs ranged from 18 to 52 mm Hg. All anesthetics resulted in a statistically significant (P: < 0.01) reduction in measured IOP at every duration of anesthesia when compared with the corresponding awake IOP. With increasing duration of anesthesia, measured IOP decreased approximately linearly for both the anesthetic mixture and isoflurane. However, with ketamine, IOP declined to 48% +/- 11% (standard lighting) and 60% +/- 7% (constant light) of awake levels at 5 minutes of anesthesia, where it remained stable. In fellow eyes, the SD of the mean IOP in animals under anesthesia was always greater than the corresponding SD of the awake mean. Anesthesia's effects in normal eyes and eyes with elevated IOP were indistinguishable. CONCLUSIONS: All anesthetics resulted in rapid and substantial decreases in IOP in all eyes and increased the interanimal variability in IOPs. Measurement of IOP in awake animals provides the most accurate documentation of pressure histories for rat glaucoma model studies.

Acepromazine↗