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Biomedical subjects

L L Evans

Publications and source records attributed to L L Evans.

9 recordsLinked to original sources
PubMed1999

Low falls: an underappreciated mechanism of injury.

OBJECTIVE: This is a retrospective study designed to evaluate the pattern and severity of injuries that result from low falls, defined as falls from less than 20 ft, subsequent mortality, and requirements of hospital resources. Our hypothesis is that many of these injuries, even without cardiopulmonary instability, are worthy of trauma center care. METHODS: The records of all patients entered into the hospital trauma registry at an urban Level I trauma center during the years 1991 through 1997 who suffered low falls and who either died after admission or were hospitalized for at least 3 days were reviewed. Patients suffering isolated hip fractures were excluded. One hundred seventy-six patients constituted the study population. This group accounts for about 2% of all admissions for falls at our institution. Patterns of injury were examined. Age, mechanism of injury, Injury Severity Score (ISS), and cardiopulmonary or neurologic instability on admission were documented. Mortality, length of intensive care unit and hospital stays, as well as billed hospital charges, were reviewed. RESULTS: The majority of patients (62%) were younger than 50 years. Sixty patients had ISS >15 and 116 patients had ISS >9. Sixty patients had multisystem injuries requiring specialty care. Head injuries were found in 81 patients (35%), and vertebral fractures or spinal cord injuries were found in 49 patients (22%), including 9 quadriplegics and 5 paraplegics. There were seven patients with intra-abdominal injuries (five spleen and two bowel injuries). There was one patient with a rupture of the thoracic aorta. Seventeen patients had deteriorating neurologic or pulmonary function on arrival, but the majority (90%) were stable. Of the 159 "stable" patients, 48 suffered head injuries, 7 were quadriplegic, and 3 were paraplegic. All intra-abdominal injuries were in this group. Overall, 14 of 176 patients (8%) died. Seven deaths were in patients older than 60 years, and seven deaths were in younger patients (p = 0.04). The majority of deaths (9 of 14) were from head trauma. Care in the intensive care unit was required in 92 of 176 patients. Nine patients had billed charges exceeding $100,000. CONCLUSION: Low falls can cause significant injuries, most commonly to the head and spine. Based on mechanism of injury alone, patients injured in low falls might not be taken to trauma centers. We have found, however, that many of these patients sustain serious multisystem injuries, even though they are stable initially. Although these patients represent only a fraction of those who fall, our study would support adjustment of triage guidelines to recommend transport of such patients, particularly elderly patients, to trauma centers.

Accidental Falls↗
PubMed1998

Vesicle-associated brain myosin-V can be activated to catalyze actin-based transport.

Myosin-V has been linked to actin-based organelle transport by a variety of genetic, biochemical and localization studies. However, it has yet to be determined whether myosin-V functions as an organelle motor. To further investigate this possibility, we conducted a biochemical and functional analysis of organelle-associated brain myosin-V. Using the initial fractionation steps of an established protocol for the purification of brain myosin-V, we isolated a population of brain microsomes that is approx. fivefold enriched for myosin-V, and is similarly enriched for synaptic vesicle proteins. As demonstrated by immunoelectron microscopy, myosin-V associates with 30-40% of the vesicles in this population. Although a majority of myosin-V-associated vesicles also label with the synaptic vesicle marker protein, SV2, less than half of the total SV2-positive vesicles label with myosin-V. The average size of myosin-V/SV2 double-labeled vesicles (90+/-45 nm) is larger than vesicles that label only with SV2 antibodies (60+/-30 nm). To determine if these vesicles are capable of actin-based transport, we used an in vitro actin filament motility assay in which vesicles were adsorbed to motility assay substrates. As isolated, the myosin-V-associated vesicle fraction was nonmotile. However, vesicles pre-treated with ice-cold 0.1% Triton X-100 supported actin filament motility at rates comparable to those on purified myosin-V. This dilute detergent treatment did not disrupt vesicle integrity. Furthermore, while this treatment removed over 80% of the total vesicle proteins, myosin-V remained tightly vesicle-associated. Finally, function-blocking antibodies against the myosin-V motor domain completely inhibited motility on these substrates. These studies provide direct evidence that vesicle-associated myosin-V is capable of actin transport, and suggest that the activity of myosin-V may be regulated by proteins or lipids on the vesicle surface.

Actins↗
PubMed1997

Subcellular localization of myosin V in nerve growth cones and outgrowth from dilute-lethal neurons.

Myosin V-null mice (dilute-lethal mutants) exhibit apparent neurological defects that worsen from birth until death in the third postnatal week. Although myosin V is enriched in brain, the neuronal function of myosin V is unclear and the underlying cause of the neurological defects in these mice is unknown. To aide in understanding myosin V function, we examined the distribution of myosin V in the rodent superior cervical ganglion (SCG) growth cone, a well characterized neuronal structure in which myosin V is concentrated. Using affinity purified, myosin V-specific antibodies in immunofluorescence and immunoelectron microscopy, we observed that myosin V is concentrated in organelle-rich regions of the growth cone. Myosin V is present on a distinct population of small (50-100 nm) organelles, and on actin filaments and the plasma membrane. Myosin V-associated organelles are present on both microtubules and actin filaments. These results indicate that myosin V may be carried as a passenger on organelles that are transported along microtubules, and that these organelles may also be capable of movement along actin filaments. In addition, we found no abnormalities in outgrowth, morphology, or cytoskeletal organization of SCG growth cones from dilute-lethal mice. These results indicate that myosin V is not necessary for the traction force needed for growth cone locomotion, for organization of the actin cytoskeleton, or for filopodial dynamics.

Actin Cytoskeleton↗
PubMed1995

Particles move along actin filament bundles in nerve growth cones.

Organelle movement along actin filaments has been demonstrated in dissociated squid axoplasm [Kurznetsov, S. A., Langford, G.M. & Weiss, D. G. (1992) Nature (London) 356, 722-725 and Bearer, E.L., DeGiorgis, J.A., Bodner, R.A., Kao, A.W. & Reese, T.S. (1993) Proc. Natl. Acad. Sci. USA 90, 11252-11256] but has not been shown to occur in intact neurons. Here we demonstrate that intracellular transport occurs along actin filament bundles in intact neuronal growth cones. We used video-enhanced differential interference contrast microscopy to observe intracellular transport in superior cervical ganglion neurons cultured under conditions that enhance the visibility of actin bundles within growth cone lamellipodia. Intracellular particles, ranging in size from < 0.5-1.5 microns, moved along linear structures (termed transport bundles) at an average maximum rate of 0.48 micron/sec. After particle movement had been viewed, cultures were preserved by rapid perfusion with chemical fixative. To determine whether particle transport occurred along actin, we then used fluorescence microscopy to correlate this movement with actin and microtubule distributions in the same growth cones. The observed transport bundles colocalized with actin but not with microtubules. The rates of particle movement and the association of moving particles with actin filament bundles suggest that myosins may participate in the transport of organelles (or other materials) in intact neurons.

Actin Cytoskeleton↗
PubMed1995

Solute focusing techniques for bioseparations.

The growth of industrial biotechnology has had a major impact on the research and development of both analytical and preparative focusing techniques. Pioneering methods such as isoelectric focusing are being modified to overcome the limitations of batch mode operation, scale up difficulties, high power requirement, and excessive heat generation. present advances in focusing techniques have been made by either overcoming the limitations of standard techniques or by investigating new focusing systems. Here we review the background and history of isoelectric focusing and discuss several new focusing techniques including recycle isoelectric (RIEF), counteracting chromatographic electrophoresis (CACE), and countercurrent gradient chromatography (CGC).

Chromatography↗
PubMed1988

Infectious complications in patients with severe head injury.

Mortality and morbidity from head trauma have been substantially reduced by improved prehospital care and aggressive diagnostic and therapeutic management. However, a substantial number of patients will require prolonged periods of hospitalization, intensive care, and ventilator support during their recovery, placing them at risk for infectious complications. Eighty-two such patients were reviewed during a 30-month period at a Level I trauma center. Forty-one patients (50%) developed at least one infectious complication. The most common source was respiratory, occurring in 34 patients relatively early (average, 3.2 days) in their hospital course. The severity of head injury and presence of coexisting thoracic trauma correlated statistically; administration of prophylactic antibiotics and corticosteroids did not in the development of infectious problems. Only three patients died as a result of sepsis, indicating that early recognition and prompt treatment may control the severity of infectious complications.

Adolescent↗
PubMed1987

Early evaluation of cardiac injury by two-dimensional echocardiography in patients suffering blunt chest trauma.

The availability of two-dimensional echocardiography as a clinical tool has led to an interest in its applicability, usefulness, and reliability in the evaluation of blunt cardiac trauma. Forty patients who sustained objective evidence of blunt chest trauma were evaluated at our institution using serial ECGs, creatine phosphokinase (CPK) isoenzyme determinations, and two-dimensional echocardiography. Twenty patients (50%) manifested evidence of cardiac injury as demonstrated by abnormal ECGs, elevated CPK isoenzymes, or abnormal echocardiograms. Nine (23%) patients had abnormal echocardiograms with findings of pericardial effusions in four, chamber enlargement in three, and echodense areas of the right ventricle in two. There was no correlation with ECG changes or the presence of CPK isoenzymes. Based on these observations we believe echocardiography can be used as a noninvasive modality to complement other clinical tools in the detection of blunt cardiac injury.

Adult↗
PubMed1977

Monoplace hyperbaric oxygen therapy for gas gangrene.

Untreated gas gangrene is a fulminating infection that can lead to extensive tissue necrosis and death. Hyperbaric oxygen, when used with antibiotics and surgical debridement, can lead to decreased mortality. Nine patients with gas gangrene proven by positive clostridial cultures have been treated at St Luke's Hospital of Kansas City with a mortality of 11.1%. A case of gas gangrene developing from a perirectal abscess is presented.

Abscess↗