Biomedical subjects

John C Morrison

Publications and source records attributed to John C Morrison.

At least 19 recordsLinked to original sources

PubMed2006

Pregnancy loss after first-trimester viability in women with sickle cell trait: time for a reappraisal?

OBJECTIVE: The purpose of this study was to evaluate the obstetric outcomes and pathologic findings in women with sickle cell trait. STUDY DESIGN: In this retrospective case control study, pregnant women with sickle cell trait were studied over a 4-year period (2001-2005). The women who were delivered at > 16 weeks of gestation were compared with a cohort group of subjects with normal hemoglobin levels, and the placentas were sent for pathologic evaluation. RESULTS: A total of 180 pregnancies were studied with a like number of control patients. Subjects who had sickle cell trait demonstrated shorter average duration of pregnancy (233 +/- 45 days vs 255 +/- 34 days; P < .001) and lower birth weight (2114 +/- 1093 g vs 2672 +/- 942 g; P < .001). The rate of fetal death was significantly higher among study group patients (3.5% vs 9.7%; P = .015) when compared with the control group. Additionally, in study women, acute ascending amniotic infection and meconium histiocytosis were noted much more frequently. Sickling in the intervillous space and decidual vessels that were not associated with artifactual change was also found among patients sickle cell trait. CONCLUSION: Patients with sickle cell trait appear to be at increased risk for fetal loss compared with women with normal hemoglobin levels, and placental abnormalities may play a causal role.

Abortion, Spontaneous↗

PubMed2006

The use of cyclodialysis to limit exposure to elevated intraocular pressure in rat glaucoma models.

Elevated intraocular pressure (IOP) is the most common risk factor for glaucoma and pressure control is the goal of current clinical glaucoma therapy. Yet, recent clinical studies have documented that, even after therapeutic lowering of IOP, glaucomatous visual field loss can progress in many patients. Experimental elevation of IOP in the rat is commonly used to model human glaucomatous injury. However, there currently is no rodent model for the clinical situation of glaucomatous progression in eyes with apparently controlled IOP. The purpose of this study was to evaluate the ability of surgical cyclodialysis to produce both prolonged, non-injurious reduction of IOP in rat eyes and to stably normalize IOP in eyes with experimental pressure elevation. To perform cyclodialysis, a blunted spatula was fashioned from a hypodermic needle and used to separate a portion of the ciliary body from the sclera, opening a channel into the suprachoroidal space to allow aqueous outflow. Experimental IOP elevation was produced in rats by unilateral injection of hypertonic saline. Cyclodialysis in normal eyes resulted in an average 40 +/- 4% reduction in IOP, without marked hypotony. IOP lowering could be sustained for at least 6 months. The risk of retinal or optic nerve injury following a single cyclodialysis procedure was minimal as evidenced by unaltered levels of four injury-responsive retinal mRNAs and by normal optic nerve morphology. Cyclodialysis in eyes with experimental IOP elevation resulted in IOP normalization that was sustained for durations of 7 and 21 days in 88% and 53% of eyes, respectively. In addition, in eyes with the same cumulative dose of elevated IOP prior to the procedure, successful IOP normalization by cyclodialysis resulted in significantly less optic nerve injury than that seen in eyes in which IOP control was ineffective (p = 0.03). These studies show that cyclodialysis provides a simple, non-injurious method to reduce experimentally elevated IOP in rats that can be used to model the clinical situation of eyes previously damaged by pressure. This tool offers new opportunities for identifying and studying the molecular processes associated with glaucomatous progression and for testing potential neuroprotective therapies in a clinically relevant situation.

Animals↗

PubMed2006

American College of Obstetricians and Gynecologists practice bulletins: an overview.

OBJECTIVE: The purpose of this study was to review the American College of Obstetricians and Gynecologists practices bulletins to quantify the type of recommendations and references and determining whether there are any differences between obstetric and gynecologic bulletins. STUDY DESIGN: All practice bulletins published from June 1998 to December 2004 were reviewed. Odds ratios and 95% confidence intervals were calculated. RESULTS: The 55 practice bulletins contained 438 recommendations of which 29% are level A, 33% level B, and 38% level C. The 55 bulletins cite 3953 references of which 17% are level I, 46% level II, 34% level III, and 3% others. Level A recommendations were significantly more likely among the 23 gynecologic than 32 obstetric bulletins (37% versus 23%, odds ratios 1.95, 95% confidence intervals 1.28, 2.96). The study types referenced in obstetric and gynecologic bulletins were similar (P > .05 for comparison of levels I, II, and III and meta-analysis references). CONCLUSION: Only 29% of the American College of Obstetricians and Gynecologists recommendations are level A, based on good and consistent scientific evidence.

Evidence-Based Medicine↗

PubMed2006

Ludwig's angina in pregnancy.

Ludwig's angina is an infectious process involving the submental, sublingual, and submandibular spaces that can rapidly progress to hemodynamic instability and airway loss. Treatment involves antibiotics, incision, drainage and the placement of extraoral drains. This is the first reported recent case of Ludwig's angina in a pregnant patient.

Adult↗

PubMed2006

The 80-hour workweek restriction: How are OB/GYN resident procedure numbers affected?

OBJECTIVE: To evaluate the surgical caseload in a military obstetrics and gynecology residency program, prior to and after implementation of an 80-hour workweek. METHODS: A retrospective cohort study evaluating data submitted to the Accreditation Council for Graduate Medical Education (ACGME) for cumulative resident procedures in obstetrics and gynecology for the years before (July 2001-June 2002) and after (July 2002-June 2003) 80-hour workweek implementation. Total obstetric and gynecology procedures were examined using both the Student's paired t-test and a two-way mixed factor analysis of variance. RESULTS: Between July 2001 and June 2002 there were 822 gynecological cases and 3958 deliveries done by 17 OB/GYN residents; these were compared with 827 cases and 3504 deliveries done by 18 OB/GYN residents between July 2002 and June 2003 (p=0.189). The total numbers of obstetric and gynecology cases pre- and post-80-hour workweek intervention were similar when evaluated by month (July through June of 2001/2 vs. 2002/3; p=0.908). There was a significantly greater number of obstetrics cases compared with gynecological cases (p < 0.001) in the pre- vs. post-80-hour workweek groups; the number of gynecological cases remained constant in the post-80-hour workweek group while the obstetric numbers dropped (p=0.001). CONCLUSION: The 80-hour workweek restriction resulted in similar total numbers of obstetrics and gynecology cases, although the total number of obstetric cases per resident declined after implementation.

Cohort Studies↗

PubMed2006

Timing of placental delivery to prevent post-partum haemorrhage: lessons learned from an abandoned randomised clinical trial.

It has been recognised that, if the length of the third stage of labour exceeds 30 min, then there is an increased risk of a post-partum haemorrhage. Recent information has suggested that 18 min is the optimal time for removal of the undelivered placenta to prevent a post-partum haemorrhage. A randomised trial comparing 20 vs. 30 min was stopped after an interim analysis because only eight of 1607 patients' placentas had not delivered by 20 min. A third stage of labour that exceeded 10 min was observed to be significantly correlated with an increased risk of post-partum haemorrhage.

Adult↗

PubMed2005

Global tests of biodiversity concordance and the importance of endemism.

Understanding patterns of biodiversity distribution is essential to conservation strategies, but severe data constraints make surrogate measures necessary. For this reason, many studies have tested the performance of terrestrial vertebrates as surrogates for overall species diversity, but these tests have typically been limited to a single taxon or region. Here we show that global patterns of richness are highly correlated among amphibians, reptiles, birds and mammals, as are endemism patterns. Furthermore, we demonstrate that although the correlation between global richness and endemism is low, aggregate regions selected for high levels of endemism capture significantly more species than expected by chance. Although areas high in endemism have long been targeted for the protection of narrow-ranging species, our findings provide evidence that endemism is also a useful surrogate for the conservation of all terrestrial vertebrates.

Animals↗

PubMed2005

Use of fetal pulse oximetry among high-risk women in labor: a randomized clinical trial.

OBJECTIVE: The purpose of this study was to determine the clinical role of fetal pulse oximetry to reduce cesarean delivery for a nonreassuring fetal heart rate tracing. STUDY DESIGN: Singletons > or =28 weeks were randomized to fetal pulse oximetry plus electronic fetal heart rate monitoring (monitoring + fetal pulse oximetry) or monitoring alone. RESULTS: Overall, 360 women in labor were recruited: 150 cases with monitoring+fetal pulse oximetry and 177 cases with monitoring alone were analyzed. Most demographic, obstetric, and neonatal characteristics were similar. Specifically, the gestational age, cervical dilation, and station of the fetal head were not differential factors. In addition, cesarean delivery for nonreassuring fetal heart rate tracing was not different between the group with monitoring+fetal pulse oximetry (29%) and the group with monitoring alone (32%; relative risk, 0.95; 95% CI, 0.75, 1.22). Likewise, cesarean delivery for arrest disorder was similar between the group with monitoring+fetal pulse oximetry (22%) and the group with monitoring alone (23%; relative risk, 1.05; 95% CI, 0.79, 1.44). However, the decision-to-incision time was shorter for the group with monitoring+fetal pulse oximetry (17.8 +/- 8.2 min) than for the group with monitoring alone (27.7 +/- 13.9 min; P < .0001). CONCLUSION: The use of fetal pulse oximetry with electronic fetal heart rate monitoring does not decrease the rate of cesarean delivery, although it does alter the decision-to-incision time.

Adult↗

PubMed2005

Professional liability claims and Central Association of Obstetricians and Gynecologists members: myth versus reality.

OBJECTIVE: The purpose of this study was to survey members of the Central Association of Obstetricians and Gynecologists about professional liability claims. STUDY DESIGN: A survey was mailed to Central Association of Obstetricians and Gynecologists members regarding medical liability experience. RESULTS: Of the 897 surveys mailed, 73% were completed. The responding 658 clinicians had been in practice for 17,136 years and had 1507 closed claims. The respondents had a claim every 11 years of practice and a trial every 69 years. Matched for years of practice, a case control comparison indicated that the litigation is significantly lower for female physicians (1.5 +/- 1.8) than for male physicians (2.2 +/- 2.0; P = .019) although the mean cases that were dropped or dismissed were higher for men (1.3 +/- 1.7 vs 0.8 +/- 1.4; P = .022). However, the mean number of trials, defense trial verdicts, and the settlement amounts were similar for both genders. CONCLUSION: We found that professional liability claims are uncommon and that the gender of the obstetrician-gynecologist influences the litigation profile.

Adult↗

PubMed2005

Brachial plexus injury: a 23-year experience from a tertiary center.

OBJECTIVE: The purpose of this study was to analyze the data on brachial plexus injury and its relationship with shoulder dystocia from a tertiary center for a 23-year period. STUDY DESIGN: A review of the logbooks on labor and delivery and the nursery and the International Classification of Diseases codes identified all newborn infants with brachial plexus injury who were delivered at our center. RESULTS: During the 23 years (1980-2002), there were 89,978 deliveries, of which there were 85 cases of brachial plexus injury (1/1000 births) with vaginal delivery. The injury was permanent (> or =1 year) in 12% of the cases, and only 2 cases have been litigated. Newborn infants that weighed > or =4 kg were significantly more common among those infants who had shoulder dystocia and brachial plexus injury than those infants without injury (odds ratio, 6.55; 95% CI, 2.30, 18.63). The rate of permanent brachial plexus injury was similar between the 2 groups. CONCLUSION: A case of brachial plexus injury occurs 1 time in every 1000 births, is permanent in 1 of every 10,000 deliveries, and is litigated 1 time for every 45,000 deliveries. The infrequent nature of injury may preclude prevention.

Adult↗

PubMed2005

Timing of prophylactic antibiotic administration in the uninfected laboring gravida: a randomized clinical trial.

OBJECTIVE: The purpose of this prospective study was to determine whether the timing of prophylactic antibiotics at cesarean delivery influences maternal/neonatal infectious morbidity. STUDY DESIGN: In this double-blind placebo-controlled trial, cefazolin was given at skin incision (group A) or at cord clamping (group B). Patients were eligible for the trial if they had labored and required a cesarean delivery. RESULTS: Over a 30-month period 303 patients with singleton pregnancies entered the trial; 153-group A, 149-group B. Demographics, indication for cesarean delivery (P = .54), and operative time (P = .999), as well as rates of endometritis (RR 0.67, 95% CI 0.42-1.07), wound infection (RR 0.84, 95% CI 0.45-1.55), neonatal sepis (RR 1.28, 95% CI 0.91-1.79), and NICU admissions (RR 1.28, 95% CI 0.91-1.79) were similar between the 2 groups. CONCLUSION: There was no difference in maternal infectious morbidity whether antibiotics were given before skin incision or at cord clamping.

Adult↗

PubMed2005

Episiotomy dehiscence that required intestinal diversion.

Postpartum episiotomy dehiscence is a rare complication of vaginal delivery. Forceps-assisted vaginal delivery over mediolateral episiotomy was complicated by infection and dehiscence with rectal injury. A diverting ileostomy was used to permit healing. Episiotomy infection requires early recognition and thorough evaluation to exclude occult rectal injury.

Adult↗

PubMed2005

Age related optic nerve axonal loss in adult Brown Norway rats.

The effect of age on the number and morphology of optic nerve axons in adult Brown Norway rats (5-31 months old) (n=29) was examined using transmission electron microscopy (TEM). By manually counting every axon in areas representing 60% of the optic nerve cross-section, we found a significant negative correlation between age and axon count (R(2)=0.18, P<0.05). However, when the oldest animals were omitted, the relationship was no longer statistically significant. Simultaneously, the proportion of spontaneously degenerating axons increased at an exponential rate (R(2)=0.79, P<0.05), with significantly more degeneration in the 31-month group than in 5-month-old animals (ANOVA, P<0.05). This study demonstrates, using quantitative TEM methods, that optic nerve axonal numbers are relatively constant throughout the majority of the adult life of the Brown Norway rat, an increasingly popular strain for glaucoma research. Total axonal loss with aging is substantially less than that reported for other strains. The reduction in axonal numbers and the rate of axonal degeneration do not appear significantly altered until the last few months of life, failing to support some studies that have concluded that optic nerve axon loss in adult rats is linear. However, they do agree with other studies in the rat, and a similar study performed in non-human primate eyes, that concluded that aging changes in the optic nerve and retina follow a complex pattern. Therefore, the impact of animal age must be considered when modeling the course and pathophysiology of experimental glaucomatous optic nerve damage in rats.

Aging↗

PubMed2005

Understanding mechanisms of pressure-induced optic nerve damage.

Patients with glaucoma can suffer progressive vision loss, even in the face of what appears to be excellent intraocular pressure (IOP) control. Some of this may be secondary to non-pressure-related (pressure-independent) factors. However, it is likely that chronically elevated IOP produces progressive changes in the optic nerve head, the retina, or both that alter susceptibility of remaining optic nerve fibers to IOP. In order to understand the nature of these progressive changes, relevant, cost-effective animal models are necessary. Several rat models are now used to produce chronic, elevated IOP, and methods exist for measuring the resulting IOP and determining the extent of the damage this causes to the retina and optic nerve. A comparison of damage, pressure and duration shows that these models are not necessarily equivalent. These tools are beginning to uncover clear evidence that elevated IOP produces progressive changes in the optic nerve head and retina. In the optic nerve head, these include axonal and non-axonal effects, the latter pointing to involvement of extracellular matrix and astrocyte responses. In the retina, retinal ganglion cells appear to undergo changes in neurotrophin response as well as morphologic changes prior to actual cell death. These, and other, as yet uncovered, abnormalities in the optic nerve head and retina may influence relative susceptibility to IOP and explain progressive optic nerve damage and visual field loss, in spite of apparent, clinically adequate IOP control. Ultimately, this knowledge may lead to the development of new treatments designed to preserve vision in these difficult patients.

Animals↗

PubMed2005

Does maternal hypoglycemia during screening glucose assessment identify a pregnancy at-risk for adverse perinatal outcome?

OBJECTIVE: To determine the perinatal outcome in pregnancies with maternal hypoglycemia following a second trimester oral glucose challenge test (GCT). STUDY DESIGN: Retrospective case-control study of pregnancies undergoing a second trimester 1-hour oral glucose challenge test (GCT). Hypoglycemic pregnancies (<88 mg/dl) were matched with pregnancies with 1-hour glucoses of >88 mg/dl. Antepartum, intrapartum, and neonatal outcomes were assessed. RESULTS: Over 29 months, 334 hypoglycemic singleton pregnancies were matched with 334 controls. A greater number of special/neonatal intensive care unit (SCN/NICU) admissions occurred in the hypoglycemic group (48/334 (14.4%) vs 29/334 (8.7%) in the control group) (p=0.02). The SCN/NICU admission rate remained after controlling for maternal hypertension, smoking, and preterm birth (p=0.037). The development of pregnancy-induced hypertension in women with hypoglycemia 24/334 (7.2%) compared with euglycemic women 13/334 (3.9%, p<0.06) was not significant. CONCLUSION: Admission to SCN/NICU is increased in pregnant women with hypoglycemia following a GCT.

Adolescent↗

PubMed2005

Neonatal organ dysfunction among newborns at gestational age 34 weeks and umbilical arterial pH<7.00.

PURPOSE: Among newborns at 34 weeks or more with umbilical arterial pH<7.00, we endeavoured to determine the pH threshold and risk factors for neonatal organ injury within 72 hours of birth. STUDY DESIGN: Retrospectively, all non-anomalous newborns delivered over 6 years near term with a low pH were identified. Each case of a newborn with injury was compared with the next four neonates with a pH below 7.00 and no injury. A receiver-operating characteristic (ROC) curve and unconditional logistic regression was used. RESULTS: Of the 87 newborns with pathologic acidosis, 16% had neonatal organ system injury. Inspection of the ROC curve indicates that a pH of 6.92 is the threshold that identifies newborns who will have damage to organs. Unconditional logistic regression analysis indicates that the significant risk factors for morbidity were an Apgar score or=37 weeks, pH <or=6.92 is the threshold linked with neonatal organ dysfunction.

Acid-Base Imbalance↗

PubMed2005

A review of sonographic estimate of fetal weight: vagaries of accuracy.

PURPOSE: To determine the factors that might influence the accuracy of sonographic estimated fetal weight. STUDY DESIGN: A PubMed search (Jan 1975 to Jan 2003) of articles published in the English language was carried out and the inclusion criterion was that estimates were within 10% of birth weight. A Chi-square test for trend was used and odds ratio (OR) with 95% confidence intervals (CI) was calculated. RESULTS: Over 28 years, 175 articles were identified but only 54 (31%) met the inclusion criterion. Overall 62% (8895/14 384) of the predictions were within 10% of the actual weight. The accuracy was significantly different in articles where <7 vs. >7 days were allowed to lapse between examination and delivery (OR 2.17, 95% CI 1.93, 2.45); where examinations were done by registered diagnostic medical sonographers (RDMS; 65%) versus physicians (59%) or residents (57%; p < 0.0001); in term vs. preterm patients (OR 1.97, 95% CI 1.67, 2.13); and in studies with >1000 vs. <1000 cohorts (OR 1.62; 95% CI 1.51, 1.74). CONCLUSIONS: If feasible the sonographic examination should be done by RDMS and within a week of delivery.

Birth Weight↗

PubMed2005

The effects of standing, lifting and noise exposure on preterm birth, growth restriction, and perinatal death in healthy low-risk working military women.

OBJECTIVE: The effects of standing, lifting and noise in low-risk, healthy pregnant women are uncertain. In the past, the heterogeneity of the populations studied, the limitations of the designs of the retrospective and case control studies, and a failure of some of the larger investigations to evaluate all the potential confounding variables has hampered many studies. The purpose of this investigation was to evaluate, throughout pregnancy, the effects of standing, repetitive lifting, and noise in the workplace compared with no standing, lifting or noise exposure, on maternal and perinatal outcomes in a large prospective study of a low-risk healthy population of working women cared for by a single group of health providers. METHODS: This prospective observational study used an extensive questionnaire to collect antepartum, intrapartum, and postpartum information. Information was collected on the initial visit, each subsequent visit, and immediately after delivery. The participating women were divided into groups based on the amount of time spent standing, the amount and extent of repetitive lifting, and noise exposure in the workplace. RESULTS: Eight hundred and fourteen low-risk active duty women participated in this investigation over a 4-year period. Multivariate analysis with non-exposure compared with exposure reinforced the effect of standing on preterm labor (OR 1.80, 95% CI 1.05, 3.16) and preterm birth (OR 1.69, 95% CI 1.03, 2.80) and showed a trend toward an effect of noise exposure on preterm labor (OR 1.76, 95% CI 0.78, 3.39) after controlling for other exposures. CONCLUSIONS: This investigation suggests an association of occupational standing with preterm labor and preterm birth.

Adult↗