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Biomedical subjects

M S Johnson

Publications and source records attributed to M S Johnson.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Incidence and management of arterial emboli from hemodialysis graft surgical thrombectomy.

PURPOSE: To determine the incidence and significance of arterial emboli resulting from surgical thrombectomy/revision of hemodialysis grafts. This information may help in determining the significance and management of similar emboli resulting from percutaneous hemodialysis graft thrombolysis. PATIENTS AND METHODS: Patients undergoing surgical thrombectomy/revision of clotted hemodialysis grafts are studied with postoperative fistulography per institutional protocol whenever possible. For this retrospective study, all postoperative fistulograms from a 1-year period were reviewed for the presence of arterial emboli. Patients with documented arterial emboli were examined for evidence of hand/digital ischemia; only those patients with signs or symptoms of ischemia were treated. At clinical follow-up, repeated evaluation for hand/digital ischemia was performed. RESULTS: Ninety-one thrombectomy/revision procedures were performed during the study period. Postoperative fistulograms were obtained after 67 of these procedures in 32 patients. One patient complained of hand pain during dialysis prior to acquisition of the postoperative fistulogram. Arterial emboli were documented in eight patients (12%; brachial, n = 3; radial, n = 2; ulnar, n = 2; radial/ulnar, n = 1). The single symptomatic brachial embolus was percutaneously removed; no intervention was undertaken in the remainder. At mean follow-up of 14 months, no patient had developed hand or digital ischemia. Subsequent fistulograms demonstrated partial (n = 2) or complete (n = 2) resolution of the untreated emboli. CONCLUSION: Arterial emboli are a relatively common occurrence with surgical thrombectomy/revision. Conservative management appears to be indicated in asymptomatic patients.

Angiography↗
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Comparison of digital subtraction and cut film arteriography in the evaluation of suspected thoracic aortic injury.

PURPOSE: To determine whether intraarterial digital subtraction arteriography (DSA) is as sensitive and specific as cut film arteriography (CFA) in the evaluation of suspected aortic injury resulting from blunt chest trauma. MATERIALS AND METHODS: Both CFA and DSA images of the thoracic aorta were obtained in the right posterior oblique (RPO) projection in 100 of 103 consecutive patients undergoing arteriography after blunt chest trauma. Diagnoses based on blinded separate review of both studies (CFA vs DSA) by four independent reviewers were compared. Reviewers graded their confidence in their diagnoses from 1 (certain) to 10 (uncertain). RESULTS: Eleven of 100 patients had aortic or great vessel injuries confirmed by operation (n = 10) or transesophageal echocardiography (n = 1). Three hundred eighty-eight of 400 diagnoses based on RPO CFA and 390 of 400 diagnoses based on RPO DSA agreed with the correct diagnoses. The sensitivity, specificity, and diagnostic accuracy of CFA versus DSA were not significantly different. The reviewers' confidence in their diagnoses was equivalent between CFA (average confidence score, 1.373) and DSA (average confidence score, 1.375). CONCLUSION: DSA and CFA yield equivalent sensitivity, specificity, and diagnostic accuracy in the evaluation of blunt chest trauma.

Adolescent↗
PubMedDate not supplied

Phantom for calibration of preoperative imaging modalities in endoluminal stent-graft repair of aortic aneurysms.

PURPOSE: Successful deployment of an endoluminal prosthesis for repair of an abdominal aortic aneurysm (AAA) is critically dependent on accurate preoperative assessment of aneurysm morphology with use of such modalities as contrast aortography (CA), spiral computed tomography (CT), magnetic resonance (MR) imaging, and intravascular ultrasonography (IVUWS). The authors describe a new phantom that could be used both to calibrate these four imaging modalities and to determine which imaging technique(s) is (are) best for preoperative AAA sizing. MATERIALS AND METHODS: A life-sized AAA model was constructed of silicone elastomers with luminal access ports for introduction of contrast media and catheters. Contrast material-filled rings were positioned circumferentially along the length of the model as reference points for dimension measurements. The modalities were compared to each other relative to the actual dimensions of the model, as determined at its construction. RESULTS: In this pilot study, all modalities were relatively similar in their ability to measure the dimensions of the AAA model. Length measurements accounted for most of the interinstitutional and interobserver variability. MR imaging had the least variability. CONCLUSIONS: The authors developed a new phantom that can be imaged successfully with CA, CT, MR imaging, and IVUS in repetitive, reproducible fashion. Structural refinements and future larger scale, statistically significant evaluations of such models should establish this as a useful adjunct in multicenter endoluminal stent-graft trials to allow calibration of imaging modalities and to determine which modality or modalities is (are) best for preoperative AAA sizing.

Aortic Aneurysm, Abdominal↗
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The emergency medical services system response to a commercial airliner incident at the very remote location of Shemya, Alaska.

INTRODUCTION: A multiple patient incident involving a commercial airliner is a challenge for any community EMS system. When the community is on a remote island in the North Pacific Ocean, where there is no hospital and only a small clinic staffed by just one physician and several nurses and technicians, the challenge is much greater. The incident described herein necessitated providing emergency care at the airport, and at the same time, activating a response capability from hundreds of miles away to transport the patients to definitive care. The situation was compounded further by the fact that most of those injured spoke little or no English. This paper reviews the events that occurred and the lessons learned. OBJECTIVE: To identify the events that occurred when a commercial airliner, with more than 250 passengers and crew aboard, experienced an in-flight "upset" that resulted in many being injured. What was learned may help other areas be better prepared for such events. STUDY POPULATION: A commercial airliner incident that occurred in April, 1993 resulted in the need for emergency medical care at the remote island location of Shemya, Alaska initially, and fixed-wing transport of the injured to definitive care in Anchorage, Alaska, USA, which is about 1,300 miles (2,130 km) from Shemya. METHODS: A case review methodology was used that included interviews with key persons involved in the response to this incident to learn first-hand what occurred; by review of the National Transportation Safety Board (NTSB), reports, and by having agencies involved in the event review draft report materials to ensure accuracy. RESULTS: This study showed how a remote site with a small cadre of medically trained personnel could organize and effectively provide initial emergency care for > 200 persons, and have them transported more than a thousand miles to definitive care. CONCLUSIONS: Valuable lessons were learned from this incident that may help other areas be better prepared, particularly in remote areas, for large multiple patient events.

Accidents, Aviation↗
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Computer-based characterization of epidermal growth factor precursor.

The cDNA sequence of the precursor of mouse epidermal growth factor (EGFP) has recently been reported by two groups, both of whom noted the presence of repeated similar segments, each about 40 residues long. One of these repeat units overlaps with the sequence of epidermal growth factor itself. The sequence of epidermal growth factor has been reported to be similar to that of pancreatic secretory trypsin inhibitor (PSTI) and a somewhat better match has been found with part of the sequence of bovine factor X, one of the blood coagulating factors. We report here that there is an even stronger similarity between the sequences of some of the repeat units of epidermal growth factor precursor and certain segments in factor X. This sequence similarity is also apparent in comparisons with other blood coagulation factors. On the basis of these sequence comparisons we suggest a scheme for the evolution of the epidermal growth factor precursor. We have also identified certain structural features in the precursor sequence that bear on the way in which the mature epidermal growth factor is generated.

Amino Acid Sequence↗
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Domainal evolution of a prokaryotic DNA repair protein and its relationship to active-transport proteins.

The ABC excision nuclease of Escherichia coli is an ATP-dependent DNA repair enzyme composed of three protein subunits, UvrA, UvrB and UvrC. The DNA sequences of all three genes have been reported. UvrA, the component that binds directly to the DNA, and UvrB, which attaches itself to the UvrA-DNA complex, both contain consensus sequences though to be diagnostic of ATP-binding sites, although the UvrC sequence does not. We now report that a computer analysis of the UvrA sequence has revealed an unusual series of internal duplications centering around putative metal-binding sites which may be involved in the interaction with DNA. We also find a strong evolutionary relationship to a family of prokaryotic membrane-associated active-transport proteins.

Amino Acid Sequence↗
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Stent grafting of abdominal aortic aneurysms: pre-and postoperative evaluation with multislice helical CT.

Endovascular stent grafting of abdominal aortic aneurysms is a new technique that may replace open surgery in selected cases. Pre-and postoperative angiography can be replaced by helical CT. This pictorial essay describes and illustrates the use of multislice helical CT where maximum intensity projection and multiplanar reformats play a central role in the evaluation.

Aged↗
PubMedDate not supplied

Effects of 2,4,6-trinitrotoluene in a holistic environmental exposure regime on a terrestrial salamander, Ambystoma tigrinum.

2,4,6-Trinitrotoluene (TNT) is a defense-related environmental contaminant present at high concentrations in soil at some military installations. Tiger salamanders (Ambystoma tigrinum, family Ambystomatidae) were exposed to TNT in a soil matrix and fed earthworms that had also been exposed to TNT via contaminated soil. Such exposure was previously shown to result in significant accumulation of both TNT and TNT metabolites by salamanders. Following 14 days of combined oral and dermal exposures, salamanders were evaluated for signs of toxicity. Control and TNT-exposed salamanders gained weight (p < 0.025). In addition, organ to body weight ratios (kidney, liver, and spleen) were not affected by treatment. The function of splenic phagocytic cells was evaluated because these cells are sensitive to certain environmental chemical exposures. Neither the chemiluminescence response (H2O2 production) nor the phagocytic capacity of such cells were different between controls and treatment groups. In like manner, no changes were seen in the peripheral hematologic parameters investigated. Histopathologic evaluations were inconclusive, yet the liver revealed the presence of heavily pigmented iron-rich phagocytes (melanomacrophages). This investigation presents a realistic approach and preliminary data for investigating the effects of xenobiotic exposure in a soil matrix on a terrestrial vertebrate.

Administration, Cutaneous↗
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The tale of the tragedy of Neftegorsk.

An earthquake with a magnitude of 7.6 struck the town of Neftegorsk (population about 3,000) on 27 May, 1995. This paper describes the devastation and the human aspects of the catastrophe of the first week following the quake. A total of 1,995 persons were found dead under the rubble, including 268 children less than 16 years of age. There were 1,144 survivors. A total of 406 person were rescued alive from under the rubble of which an additional 37 persons died in a hospital following rescue. Most of the survivors have been relocated, but some remain in the area. There remains a need for psychological support for the survivors and rescuers.

Adult↗
PubMedDate not supplied

Serious and fatal firearm injuries among children and adolescents in Alaska: 1991-1997.

STUDY OBJECTIVE: To describe demographics, causal factors, intent, and incident locations of serious and fatal firearm injuries among children and adolescents in Alaska, for the years 1991 through 1997. METHODS: Data from the Alaska Trauma Registry plus Vital Statistics death certificates were reviewed for a seven-year period (1991-1997). Data elements included are: intent (ICD 9-CM E-Codes and narratives); age group; region of incident; place of occurrence; alcohol or drug involvement; type of firearm used; and perpetrator. RESULTS: During the seven-year study period, 222 children and adolescents ages 0-19 years were admitted to a hospital for a non-fatal firearm injury, plus 165 others received fatal firearm injuries. Of these 387 serious and fatal injuries, 34.9% (135) were determined to be unintentional, 36.4% (141) were suicides or suicide attempts, 23.3% (90) were homicide/assaults, 0.5% (2) were legal intervention, and for 4.9% (19) intent was unknown. Rates of serious and fatal firearm injuries per 100,000 youth for the six-year study period ranged from 14 in the Fairbanks North Star Borough and the Kenai Peninsula Borough to 105 in the Yukon-Kuskokwim Region. The statewide average for this period was 27.1 per 100,000 children and adolescents. CONCLUSIONS: Firearm injuries are a leading cause of serious and fatal injuries to children and youth in Alaska. This study suggests that many children and adolescents in Alaska who were injured by firearms, or who caused injury to other children or youth by firearms, had easy access to them. Efforts should be made to convince adults not to let children or at risk teenagers have unsupervised access to firearms, and to promote safe storage of firearms.

Accidents↗
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The Alaska Trauma Registry.

Recognizing that injury is the leading cause of death and disability for virtually all age groups in Alaska, a trauma task force was developed in the Anchorage area in the early 1980s. This task force established the trauma registry pilot project in the state of Alaska. The Emergency medical Services Section, Department of Health and Social Services provided the funding to the Southern Region Emergency Medical Services Council, Inc. and the Alaska Chapter of the American College of Surgeons Committee on Trauma to develop this pilot project. The funding originated from a federal grant from the National Highway Traffic Safety Administration. Seven hospital participated in the pilot project which lasted approximately two and one half years. There were 5,087 entries into the registry with information on 4,860 patients. The rationale, methodology, and development of the registry, as well as some of the data accumulated is presented. The potential usefulness of the registry as a quality improvement tool and as an extensive data base for injury prevention and trauma care research also is discussed.

Adolescent↗
PubMedDate not supplied

Alaska/Magadan EMS project: phase two.

In July, 1991, five members of the Alaska/Magadan Medical Exchange group visited the Magadan/Chukotka Region of the Soviet Far East, to continue studies of the emergency medical services (EMS) system, and to implement recommendations for system improvement developed during the previous year. During this exchange visit, major efforts focused on development of a rapid defibrillation system for the city of Magadan, technical assistance and training to upgrade burn treatment capabilities, and training and equipping prehospital emergency medical service providers to perform spinal immobilization techniques on traumatic injury patients. Further studies were conducted to compare EMS in the Magadan/Chukotka Region with EMS in Alaska, and recommendations are being presented for further collaborative projects.

Alaska↗