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Biomedical subjects

J A Morris

Publications and source records attributed to J A Morris.

At least 37 records · Page 2Linked to original sources
PubMed2001

The effects of altitude on heavy-duty diesel truck on-road emissions.

On-road measurements of carbon monoxide, hydrocarbons, and nitric oxide from 5772 heavy-duty diesel trucks at five locations in the United States and Europe show slightly increasing emissions with increasing altitude. The result for nitric oxide showed a statistically significant increase of 4.1 +/- 1 gNO/kg of fuel consumed/km increase in altitude. The increases for CO and HC were also statistically significant.

Air Pollutants↗
PubMed2001

Anatomy and three-dimensional reconstructions of the brain of the white whale (Delphinapterus leucas) from magnetic resonance images.

Magnetic resonance imaging offers a means of observing the internal structure of the brain where traditional procedures of embedding, sectioning, staining, mounting, and microscopic examination of thousands of sections are not practical. Furthermore, internal structures can be analyzed in their precise quantitative spatial interrelationships, which is difficult to accomplish after the spatial distortions often accompanying histological processing. For these reasons, magnetic resonance imaging makes specimens that were traditionally difficult to analyze, more accessible. In the present study, images of the brain of a white whale (Beluga) Delphinapterus leucas were scanned in the coronal plane at 119 antero-posterior levels. From these scans, a computer-generated three-dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three-dimensional space, was then resectioned in orthogonal planes to produce corresponding series of "virtual" sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of such structures as the corpus callosum, internal capsule, cerebral peduncles, cerebral ventricles, certain thalamic nuclear groups, caudate nucleus, ventral striatum, pontine nuclei, cerebellar cortex and white matter, and all cerebral cortical sulci and gyri.

Animals↗
PubMed2001

Needle thoracostomy may not be indicated in the trauma patient.

OBJECTIVE: The aim of this study was to evaluate the usefulness of needle thoracostomy catheter (NTC) placement in trauma. METHODS: A consecutive case series was conducted from November 1996 to September 1997. All patients admitted to a level I trauma centre who had NTCs placed prior to arrival in the Emergency Department were included. No patients were excluded or omitted. During the course of the study 2801 patients were admitted to our trauma centre. Nineteen patients (0.68%) had NTCs placed prior to arrival in the emergency department. RESULTS: Twenty-five needle thoracostomies were performed in 19 patients. This group represented 0.68% of the trauma admissions. Four patients were found to have evidence of a pneumothorax with an air leak (28%). The NTC failed to decompress the chest in one of two patients who had physiologic evidence of a tension pneumothorax. Eleven patients (58%) were endotracheally intubated prior to NTC. CONCLUSIONS: This study suggests that field NTC placements are often ineffective and may be over-used. Further study on the usefulness of NTC is required.

Emergency Medical Services↗
PubMed2001

Association of parental psychological and behavioral factors and children's syncope.

The authors examined the associations between parental variables and child syncope (fainting). Children ages 7 to 18 years undergoing tilt-table testing for neurocardiogenic syncope (NCS) at a pediatric cardiac center served as participants (N = 56). Results revealed that fathers' shortness of breath and overall psychological distress were significantly related to syncope frequency and emergency room (ER) visits for girls. Mothers' overall psychological distress, depressive symptoms, and shortness of breath were associated with boys' frequency of syncope and ER visits. Fathers' psychological factors were highly correlated with syncope for the children diagnosed negative for NCS. The frequency of children's syncope was higher in stepfamilies than in homes with both biological parents, and the correlations between children's syncope and the stepfathers' psychological symptoms were greater than for the children and their biological fathers in intact families. The role of parental psychological factors on child syncope is supported.

Adolescent↗
PubMed2001

How many deleterious mutations are there in the human genome?

An estimate of the number of deleterious mutations in the human genome is made using data on the frequency of rare recessive disease in cousin marriages and in the general population. Sexual reproduction ensures that deleterious mutations are distributed at random in zygotes with an approximate Poisson distribution. The mean of this distribution is the sum of the mean number of deleterious mutations in zygotes which contribute to the next generation (Y) and the mean number of new mutations which arise in each human generation (X). The estimates are that X is between 1 and 2.6 and Y is between 12 and 32. A mathematical model based on redundancy is then used to predict how zygote survival will vary with the number of deleterious mutations. The form of this relationship is the same as that seen in experiments on cell survival following radiation-induced mutational damage and this provides independent support for this theoretical approach. The zygotes that survive to contribute to the next generation have a skewed distribution with a mean of Y. It is argued that the number of deleterious mutations in the genome is an important variable in health and disease.

Genes, Recessive↗
PubMed2001

Prospective comparison of admission computed tomographic scan and plain films of the upper cervical spine in trauma patients with altered mental status.

OBJECTIVE: The accurate evaluation of patients with multiple injuries is logistically complex and time sensitive, and must be cost-effective. We hypothesize that computed tomographic (CT) scan of the upper cervical spine (occiput to C3 [Co-C3]) would add little to the initial evaluation of patients with multiple injuries who have altered mental status. METHODS: The study consisted of a prospective, unblinded, consecutive series. Patients met entry criteria if they had sustained a blunt mechanism of injury and had an altered mental status requiring CT scan of two or more body systems. All patients received CT scan of Co-C3 with 2-mm cuts and subsequent reconstructions as well as five-view cervical spine plain films. Cervical spine injury was defined as any radiographically identified fracture or subluxation that required treatment. Patients were excluded if they died or were cleared clinically before plain film series were obtained. CT scan of Co-C3 and cervical spine films were reviewed by two different attending radiologists. RESULTS: Of the 2,690 consecutive admissions between December 1998 and November 1999, 1,356 patients met entry criteria. Seventy patients (5.2%) had a total of 95 injuries to the upper cervical spine. CT scan of Co-C3 identified 67 of 70 patients and plain films identified 38 of 70 patients with injuries to the upper cervical spine. Twelve patients (17%) had neurologic deficits attributable to Co-C3 injuries. Three patients had false-negative CT scans of Co-C3, and one patient was quadriplegic. There were 32 patients with false-negative plain films, including four patients with motor deficits (one with quadriplegia). Use of the guidelines developed by the Eastern Association for the Surgery of Trauma identified all patients with upper cervical spine injuries; to date, no patient in the study group was readmitted or has initiated a lawsuit for missed injury of the upper cervical spine. CONCLUSION: CT scan of Co-C3 was superior to plain films in the early identification of upper cervical spine injury. Plain films failed to identify 45% of upper cervical spine injuries; four of these missed injuries resulted in motor deficits. Our study supports the practice guidelines developed by the Eastern Association for the Surgery of Trauma for clearance of the upper cervical spine in patients with altered mental status, as all patients with injuries were identified using these guidelines.

Adolescent↗
PubMed2001

Contribution of age and gender to outcome of blunt splenic injury in adults: multicenter study of the eastern association for the surgery of trauma.

BACKGROUND: The purpose of this study was to examine the contribution of age and gender to outcome after treatment of blunt splenic injury in adults. METHODS: Through the Multi-Institutional Trials Committee of the Eastern Association for the Surgery of Trauma (EAST), 1488 adult patients from 27 trauma centers who suffered blunt splenic injury in 1997 were examined retrospectively. RESULTS: Fifteen percent of patients were 55 years of age or older. A similar proportion of patients > or = 55 went directly to the operating room compared with patients < 55 (41% vs. 38%) but the mortality for patients > or = 55 was significantly greater than patients < 55 (43% vs. 23%). Patients > or = 55 failed nonoperative management (NOM) more frequently than patients < 55 (19% vs. 10%) and had increased mortality for both successful NOM (8% vs. 4%, p < 0.05) and failed NOM (29% vs. 12%, p = 0.054). There were no differences in immediate operative treatment, successful NOM, and failed NOM between men and women. However, women > or = 55 failed NOM more frequently than women < 55 (20% vs. 7%) and this was associated with increased mortality (36% vs. 5%) (both p < 0.05). CONCLUSION: Patients > or = 55 had a greater mortality for all forms of treatment of their blunt splenic injury and failed NOM more frequently than patients < 55. Women > or = 55 had significantly greater mortality and failure of NOM than women < 55.

Adult↗
PubMed2001

Demonstrating the cost effectiveness of an expert occupational and environmental health nurse: application of AAOHN's success tools. American Association of Occupational Health Nurses.

According to DiBenedetto, "Occupational health nurses enhance and maximize the health, safety, and productivity of the domestic and global work force" (1999b). This project clearly defined the multiple roles and activities provided by an occupational and environmental health nurse and assistant, supported by a part time contract occupational health nurse. A well defined estimate of the personnel costs for each of these roles is helpful both in demonstrating current value and in future strategic planning for this department. The model highlighted both successes and a business cost savings opportunity for integrated disability management. The AAOHN's Success Tools (1998) were invaluable in launching the development of this cost effectiveness model. The three methods were selected from several tools of varying complexities offered. Collecting available data to develop these metrics required internal consultation with finance, human resources, and risk management, as well as communication with external health, safety, and environmental providers in the community. Benchmarks, surveys, and performance indicators can be found readily in the literature and online. The primary motivation for occupational and environmental health nurses to develop cost effectiveness analyses is to demonstrate the value and worth of their programs and services. However, it can be equally important to identify which services are not cost effective so knowledge and skills may be used in ways that continue to provide value to employers (AAOHN, 1996). As evidence based health care challenges the occupational health community to demonstrate business rationale and financial return on investment, occupational and environmental health nurses must meet that challenge if they are to define their preferred future (DiBenedetto, 2000).

Cost-Benefit Analysis↗
PubMed2000

In vitro evolution of the hammerhead ribozyme to a purine-specific ribozyme using mutagenic PCR with two nucleotide analogues.

The conventional hammerhead ribozyme cleaves RNA 3' to nucleotide triplets with the general formula NUH, where N is any nucleotide, U is uridine and H is any nucleotide except guanosine. In order to isolate hammerhead ribozyme sequences capable of cleaving 3' to the GUG triplet, we performed a mutagenic selection protocol starting with the conventional sequence of an NUH-cleaving ribozyme. The 22 nucleotides in the core and the stem-loop II region were subjected to mutagenic PCR using the two nucleotide analogues 6-(2-deoxy-beta-d-ribofuranosyl)-3,4-dihydro-8H-pyrimido-[4,5-C)][1, 2] oxazin-7-one and of 8-oxo-2'-deoxyguanosine. After five repetitions of the selection cycle, several clones showed cleavage activity. One sequence, having one deletion, showed at least a 90 times higher in trans cleavage rate than the starting ribozyme. It cleaved 3' to GUG and GUA. The sequence of this ribozyme is essentially identical with that obtained previously by selection for AUG cleavage starting with a randomised core and stem-loop II region. This identical result of two independent selection procedures supports the notion that sequences for NUR cleavage, where R is a purine nucleotide, are not compatible with the classical hammerhead structure, and that the sequence space for this cleavage specificity is very limited. The cleavage of NUR triplets is not restricted to the sequence of the substrate that was used for selection but is sequence-independent for in trans cleavage, although the sequence context influences the value for the cleavage rate somewhat. Analysis of cleavage activities indicates the importance of A at position L2.5 in loop II.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Positional cloning utilizing genomic DNA microarrays: the Niemann-Pick type C gene as a model system.

A major obstacle in positional cloning is identifying the specific mutated gene from within a large physical contig. Here we describe the application of DNA microarray technology to a defined genomic region (physical map) to identify: (i) exons without a priori sequence data and (ii) the disease gene based on differential gene expression in a recessive disorder. The feasibility was tested using resources from the positional cloning of the Neimann-Pick Type C (NP-C) disease gene, NPC1. To identify NPC1 exons and optimize the technology, an array was generated from genomic fragments of the 110-kb bacterial artificial chromosome, 108N2, which encodes NPC1. First, as a test case for blindly identifying exons, fluorescently labeled NPC1 cDNA identified 108N2 fragments that contained NPC1 exons, many of which also contained intronic sequences and could be used to determine part of the NPC1 genomic structure. Second, to demonstrate that the NPC1 disease gene could be identified based upon differential gene expression, subarrays of 108N2 fragments were hybridized with fluorescently labeled cDNA probes generated from total RNA from hamster cell lines differentially expressing NPC1. A probe derived from the NP-C cell line CT60 did not detect NPC1 exons or other genomic fragments from 108N2. In contrast, several NPC1 exons were detected by a probe generated from the non-NP-C cell line 911D5A13, which was derived from CT60, and expressed NPC1 as a consequence of stable transduction with a YAC that contains NPC1 and encompasses 108N2. Thus, the array technology identified NPC1 as a candidate gene based on a physical contig and differential NPC1 expression between NP-C and non-NP-C cells. This technique should facilitate gene identification when a physical contig exists for a region of interest and mutations result in changes in the mRNA level of the disease gene or portions thereof.

Animals↗
PubMed2000

Hypothermia, coagulopathy, and acidosis.

The management of patients requiring a damage control approach taxes the abilities of the best equipped trauma center. These patients present with severe metabolic abnormalities, most notably characterized by a deadly triad of hypothermia, coagulopathy, and acidosis. Using volumetric, oxymetric pulmonary artery catheters, hypothermia and any ongoing cardiovascular abnormalities can be identified quickly and treatment can be monitored. External, forced air rewarming is a valuable technique in treating the patient with hypothermia, as are more invasive modalities, including body cavity lavage. Although there is no shotgun approach to blood component transfusion therapy, the coagulopathy shown by these patients has a time course that is more rapid than stat laboratories can presently keep up with. Given the fulminant nature of this coagulopathy, the authors feel justified in empirically initiating platelet and plasma or cryoprecipitate transfusion on identification of visible coagulopathy. The willingness of trauma surgeons to push the envelope in treating these most severely afflicted patients has allowed patients who once would have certainly died to lead meaningful lives.

Acidosis↗
PubMed2000

Role utilization of nurses in public psychiatry.

This study examined the professional, work and organizational characteristics, and the actual and preferred work activities of nurses employed by one state mental health agency. Findings include neutral ratings by this older and experienced group of nurses in relation to job satisfaction, work autonomy, and organizational commitment regardless of educational background or work setting. Specific activities of the nurses varied appropriately based on education, but differences emerged among functions performed by nurses in inpatient and community settings. All nurses preferred to increase their direct care activities and significantly reduce their clerical activities. Factors related to the appropriate utilization of public sector psychiatric nurses are analyzed.

Adult↗
PubMed2000

Playing policy pinball: making policy analysis palatable.

The author presents a teaching tool to make policy analysis accessible to a wide range of audiences, especially those who might normally be reluctant to engage in policy discussions or debate. The tool has been used with good results in a variety of venues, and is presented with brief examples of how it can be used.

Economics↗
PubMed2000

Anterior ischemic optic neuropathy: a complication after systemic inflammatory response syndrome.

BACKGROUND: Patients are surviving previously fatal injuries. Unique morbidities are occurring in these survivors. Anterior ischemic optic neuropathy represents a previously unrecognized cause of blindness in the trauma victim. We hypothesize that this phenomenon is caused by unique characteristics of optic edema/ pressure or decreased blood flow associated with massive resuscitation. METHODS: Between November of 1991 and August of 1998, there were 18,199 admissions to our trauma center. Of this group, 350 patients required massive volume resuscitation (>20 liters infused over first 24 hours). Patients having closed head injuries, facial fractures or direct orbital trauma were excluded from study. The following variables were studied: demographics, injury severity (Injury Severity Score, highest lactate, worst base deficit, and lowest pH) crystalloid and transfusion requirements, ventilator requirements (PEEP) RESULTS: Of the 350 patients with massive resuscitation, 9 patients were diagnosed with anterior ischemic optic neuropathy (2.6%). Of these, seven patients required celiotomy (78%). Six of the seven celiotomy patients had damage control celiotomies and abdominal compartment syndrome (86%). One patient had a repair of a subclavian artery; one had a complex acetabular repair. Blindness was unilateral in five patients and bilateral in four. All nine patients had evidence of global hypoperfusion, systemic inflammatory response, massive resuscitation, and high ventilatory support; one patient required cardiopulmonary resuscitation. CONCLUSION: Prone positioning is known to be associated with an increased intraocular pressure. We postulate that the combination of massive resuscitation and prone positioning will increase the incidence of anterior ischemic optic neuropathy. As such, we recommend that prone positioning for adult respiratory distress syndrome be reserved for only those patients at risk of death.

Adolescent↗
PubMed2000

Blunt splenic injury in adults: Multi-institutional Study of the Eastern Association for the Surgery of Trauma.

BACKGROUND: Nonoperative management of blunt injury to the spleen in adults has been applied with increasing frequency. However, the criteria for nonoperative management are controversial. The purpose of this multi-institutional study was to determine which factors predict successful observation of blunt splenic injury in adults. METHODS: A total of 1,488 adults (>15 years of age) with blunt splenic injury from 27 trauma centers in 1997 were studied through the Multi-institutional Trials Committee of the Eastern Association for the Surgery of Trauma. Statistical analysis was performed with analysis of variance and extended chi2 test. Data are expressed as mean +/- SD; a value of p < 0.05 was considered significant. RESULTS: A total of 38.5 % of patients went directly to the operating room (group I); 61.5% of patients were admitted with planned nonoperative management. Of the patients admitted with planned observation, 10.8% failed and required laparotomy; 82.1% of patients with an Injury Severity Score (ISS) < 15 and 46.6% of patients with ISS > 15 were successfully observed. Frequency of immediate operation correlated with American Association for the Surgery of Trauma (AAST) grades of splenic injury: I (23.9%), II (22.4%), III (38.1%), IV (73.7%), and V (94.9%) (p < 0.05). Of patients initially managed nonoperatively, the failure rate increased significantly by AAST grade of splenic injury: I (4.8%), II (9.5%), III (19.6%), IV (33.3%), and V (75.0%) (p < 0.05). A total of 60.9% of the patients failed nonoperative management within 24 hours of admission; 8% failed 9 days or later after injury. Laparotomy was ultimately performed in 19.9% of patients with small hemoperitoneum, 49.4% of patients with moderate hemoperitoneum, and 72.6% of patients with large hemoperitoneum. CONCLUSION: In this multicenter study, 38.5% of adults with blunt splenic injury went directly to laparotomy. Ultimately, 54.8% of patients were successfully managed nonoperatively; the failure rate of planned observation was 10.8%, with 60.9% of failures occurring in the first 24 hours. Successful nonoperative management was associated with higher blood pressure and hematocrit, and less severe injury based on ISS, Glasgow Coma Scale, grade of splenic injury, and quantity of hemoperitoneum.

Adult↗
PubMed2000

The incidence of splenectomy is decreasing: lessons learned from trauma experience.

Over the past decade, splenic preservation has become a well-reported and accepted principle in trauma management. The reasons for splenic preservation may have influenced nontraumatic surgical management as well. To investigate the changing incidence and indications for splenectomy, we conducted a 10-year review of all splenectomies at our institution. During this time, between January 1, 1986, and December 31, 1995, 896 patients underwent splenectomy. Hospital charts and records were examined to determine the etiology and incidence of splenectomy. Indications were classified as: 1) trauma, i.e., performed for blunt or penetrating injury; 2) hematologic malignancy, i.e., therapy or staging of underlying leukemia, Hodgkin's lymphoma, or non-Hodgkin's lymphoma; 3) cytopenia, i.e., treatment of thrombocytopenia, anemia, or leukopenia; 4) iatrogenic, i.e., injury during another procedure; 5) incidental, i.e., required for adjacent organ resection; 6) portal hypertension, i.e., left-sided portal hypertension or during shunting procedure; 7) diagnostic, i.e., uncertainty excluding hematologic malignancy; or 8) other, i.e., miscellaneous indications. Trauma accounted for 41.5 per cent of all splenectomies during this time period, hematologic malignancy 15.4 per cent, cytopenia 15.6 per cent, incidental 12.3 per cent, iatrogenic 8.1 per cent, portal hypertension 2.3 per cent, diagnostic 2.0 per cent, and other 2.7 per cent. Comparing the first and second 5-year time periods, the following increases/decreases in average annual incidence were noted: splenectomy for all indications, -36.9 per cent; trauma, -32.9 per cent; hematologic malignancy, -51.4 per cent; cytopenia, 35.1 per cent; incidental, -35.9 per cent; iatrogenic, -30.2 per cent; diagnostic, +4.9 per cent, and other, -57 per cent. Traumatic injury to the spleen remains the most common indication for splenectomy, but the incidence has decreased dramatically over the past 10 years. Splenectomies for treatment of hematologic malignancies and cytopenia, as well as incidental and iatrogenic splenectomies, have also decreased significantly. Only the incidence of diagnostic splenectomy has remained stable. Although initiated within the field of trauma, the advantages of splenic preservation now appear to be well recognized beyond that field.

Humans↗