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Biomedical subjects

L King

Publications and source records attributed to L King.

At least 73 records · Page 4Linked to original sources
PubMed1996

Technical skills experiences in pediatric emergency medicine fellowship programs.

Guidelines for Pediatric Emergency Medicine (PEM) fellowship programs were published by the Curriculum Subcommittee, Section of Emergency Medicine, American Academy of Pediatrics in February 1993. The guideline listed 120 technical skills that the subcommittee felt all fellows should be able to perform at the completion of their training. The purpose of this study was to measure the experience of PEM fellows in performing skills recommended by the subcommittee and to determine if documentation lists were being maintained. A written survey was mailed to 63 graduating fellows in May 1993, requesting information on the number of times procedure skills were performed. Limited experience was defined as having performed a procedure five or less times. Thirty-two surveys (51%) were returned. Eleven fellows (34%) stated they maintained a procedure documentation list. Of 117 skills analyzed, the majority of fellows had limited experience in 49 procedures and zero experience in 22 procedures. The majority of fellows had limited experience in 12 of 20 life- or limb-saving procedures and zero experience in five. Large emergency department volumes did not influence number of procedure completions. Our data indicate that graduating PEM fellows have limited experience in performing many common as well as several life- and limb-saving skills. Documentation lists of technical skills are not being maintained by most fellows.

Canada↗
PubMed1995

Protease-susceptible sites and properties of fragments of aortic smooth-muscle myosin.

We have examined the protease susceptibility of aortic myosin, the thermal unfolding profiles of myosin rod and light meromyosin (LMM) and the solubility properties of the LMM fragments. Two major protease-susceptible sites were found, located at the head-rod junction and the heavy meromyosin (HMM)-LMM junction. Both tryptic and chymotryptic digestion of aortic myosin rod produced the LMM (80-85 kDa) and short subfragment 2 (S-2) (40-45 kDa) segments, which were similar to those of gizzard myosin rod and differed from the short LMM (70 kDa) and long S-2 (58 kDa) segments produced from skeletal-muscle rod. The thermal unfolding profile of aortic myosin rods exhibited three helix-unfolding transitions, at 47.5, 51 and 54 degrees C, similar to those of gizzard rods yet different from those of skeletal-muscle rods. There was a dramatic difference in the solubility of aortic LMM fragments of various molecular mass, as for gizzard smooth-muscle LMM and rabbit skeletal-muscle LMM. LMM fragments of molecular mass 77 kDa or more were completely insoluble in low-ionic-strength buffer, whereas LMM fragments of molecular mass 73 kDa or less were completely soluble in low-ionic-strength buffer. Proteolytic digestion patterns of LMM showed two additional protease-susceptible sites located 13 and 30 kDa from the ends of the LMM molecule. This suggests the existence of flexible regions within the LMM molecule, which may be responsible for the folded form of aortic myosin.

Amino Acid Sequence↗
PubMed1995

Unfolding domains in smooth muscle myosin rod.

Gizzard smooth muscle myosin rod, an alpha-helical coiled coil, exhibits two cooperative thermal or denaturant-induced helix unfolding transitions in solutions containing 0.6 M NaCl at neutral pH, when monitored by circular dichroism at 222 nm. The first smaller transition unfolds part of the subfragment 2 (S2) domain, and the main transition unfolds the remaining helix including the light meromyosin (LMM) domain. These unfolding domains were identified by monitoring the fluorescence of acrylodan, an environmentally sensitive fluorescence probe, and the ESR signal of a maleimide spin-label, sensitive to motion, both specifically attached to Cys 43 in the S2 region of the rod sequence. The identities of the domains were verified by studying the unfolding of the S2 and LMM coiled-coil peptides obtained by proteolytic cleavage of spin-labeled and unlabeled rod. The fluorescence of acrylodan-labeled rod indicated that although the S2 intermediate is unfolded, it is not in a random-coil conformation. The unfolded S2 region stabilized the LMM domain against unfolding, possibly by a direct interaction with the LMM region. Such an interaction may be involved in the salt- and phosphorylation-dependent 6S to 10S shift in configuration of the myosin molecule.

2-Naphthylamine↗
PubMed1995

Biosynthetic conversion of phosphatidylglycerol to sn-1:sn-1' bis(monoacylglycerol) phosphate in a macrophage-like cell line.

Bis(monoacylglycerol) phosphate has a unique stereoconfiguration of sn-glycero-1-phospho-1'-sn-glycerol and is synthesized from exogenous phosphatidylglycerol by macrophages. Previous work by our laboratory showed that the macrophage-like cell line RAW 264.7 synthesizes sn-glycero-1-phospho-1'-sn-glycerol bis(monoacylglycerol) phosphate. Here we describe studies using RAW 264.7 cells that examine the biosynthetic pathway by which bis(monoacylglycerol) phosphate is formed. Experiments were conducted using precursors that were specifically radiolabeled on the glycerol backbone in order to examine the stereoconfiguration of the intermediates and products formed in intact RAW 264.7 cells. The results of our studies indicate that a complex series of reactions are involved in the synthesis of bis(monoacylglycerol) phosphate. In this proposed pathway phosphatidylglycerol is hydrolyzed to form 1-acyllysophosphatidylglycerol which is then acylated on the headgroup glycerol to form the sn-glycero-1-phospho-1'-sn-glycerol enantiomer of bis(monoacylglycerol) phosphate. The sn-glycero-1-phospho-1'-sn-glycerol enantiomer of bis(monoacylglycerol) phosphate is then thought to undergo a stereoconversion that proceeds via the required removal of the acyl group at the sn-1 position. The resulting sn-glycero-1-phospho-1'-sn-glycerol enantiomer of lysophosphatidylglycerol with the acyl moiety on the original headgroup glycerol is then acylated to form sn-glycero-1-phospho-1'-sn-glycerol bis(monoacylglycerol) phosphate.

Animals↗
PubMed1995

Molecular cloning and expression of a cDNA for human kidney cysteine conjugate beta-lyase.

Kidney cysteine conjugate beta-lyase (glutamine transaminase K, kyneurenine aminotransferase, EC 2.6.1.64) metabolises the cysteine conjugates of certain halogenated alkenes and alkanes to form reactive metabolites which can produce nephrotoxicity and neurotoxicity in experimental animals and man. Using a combination of hybridisation screening and PCR techniques we have isolated a full-length cDNA for human kidney cysteine conjugate beta-lyase. Comparison of the deduced amino acid sequence with that of the rat enzyme indicated an 82% overall similarity, with 90% similarity around the pyridoxal phosphate binding site, many of the changes being conservative in nature. Expression of the cDNA in Cos-1 cells resulted in the production of a cytosolic enzyme which showed both cysteine conjugate beta-lyase and glutamine transminase K activity. Preliminary mapping of the gene for human cysteine conjugate beta-lyase by PCR analysis of genomic DNA from human-rodent hybrid cells indicated that it is located on human chromosome 9.

Amino Acid Sequence↗
PubMed1995

Use of magnetic resonance imaging and P-31 magnetic resonance spectroscopy to detect and quantify muscle dysfunction in the amyopathic and myopathic variants of dermatomyositis.

OBJECTIVE: To investigate the use of magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (MRS) in characterizing the metabolic and functional status of muscles in patients with amyopathic dermatomyositis (DM) and to compare the findings with those in patients with classic myopathic DM. METHODS: Nine patients with amyopathic DM, 11 patients with myopathic DM, and 11 normal individuals were studied. MRI images of thigh muscles were obtained, and T1 and T2 relaxation times were calculated. Biochemical status was quantitated with P-31 MRS, by determining concentrations of phosphate metabolites during rest and exercise. RESULTS: Patients with amyopathic DM showed no muscle inflammation, and MRS data obtained during rest were normal. During exercise at 25% and 50% maximum voluntary contractile force, the MRS data revealed significant differences between amyopathic DM patients and control subjects indicating inefficient metabolism. In contrast, muscles of patients with myopathic DM showed inflammation and metabolic abnormalities even during rest. CONCLUSION: Metabolic deficiencies in patients with amyopathic DM were unmasked by exercise, suggesting that the 2 DM syndromes may share muscle abnormalities. MRI/MRS may be useful in diagnosis and optimization of treatment.

Adult↗
PubMed1995

32P-postlabeling and HPLC separation of DNA adducts formed by diesel exhaust extracts in vitro and in mouse skin and lung after topical treatment.

Diesel exhaust extracts contain many carcinogenic compounds which have been shown to form polycyclic aromatic hydrocarbon (PAH)- and nitrated PAH-DNA adducts in rodent skin and lung. The aim of this study was to characterize by 32P-postlabeling, TLC and HPLC the primary postlabeled PAH-DNA adduct(s) formed in vitro and in vivo by diesel extracts. The diesel particle extracts had known concentrations of benzo[a]pyrene, benzo[b,j,k]-fluoranthenes (B[b,j,k]F) and chrysene. DNA adducts were analyzed in calf thymus DNA incubated in vitro with PAHs activated by S9 mix and in skin and lung DNA from topically treated mice. The main diesel-derived DNA adduct formed in vitro and in vivo did not co-migrate on HPLC and large TLC plates with (+/-)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti BPDE)-, B[b]F-,B[j]F-,B[k]F-or chrysene-DNA adduct standards. By co-chromatography DNA adducts formed by chrysene from both in vitro and in vivo samples were identified. Nissan diesel extract containing higher PAH concentrations than Volkswagen automobile extract formed skin DNA adducts that co-migrated with chrysene- and anti BPDE- DNA-derived adducts. We conclude that the use of a highly sensitive 32P-postlabeling method combined with HPLC improves the identification of PAH adducts formed by complex mixtures such as diesel exhaust extracts.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1994

Conformationally altered aortic myosin light chains.

Aorta smooth myosin contains two types of light chain, LC20 and LC17, which fold together with the N-terminal region of each heavy chain to form the globular head region of myosin. We demonstrate an altered conformation of LC20 after its separation from heavy chain by high concentrations of urea, on the basis of the following evidence: 1) A polyclonal antibody against LC20 was not able to recognize this conformationally altered form; 2) Myosin reconstituted from heavy chains and urea-dissociated light chains exhibited extremely low ATPase activity. Circular dichroism unfolding profiles showed that light chains dissociated from heavy chains by SDS appeared to be more stable than those generated by urea dissociation.

Animals↗
PubMed1994

Pressure effects and thermal stability of myosin rods and rod minifilaments: fluorescence and circular dichroism studies.

In the present study hydrostatic pressure was applied upon both skeletal myosin rod molecules and rod minifilaments to learn more of the intra- and intermolecular interaction behavior of myosin. Applied pressure disassembled the rod minifilaments into individual rod molecules and dissociated each myosin rod molecule into two chains of alpha-helix. The dissociation and disassembly profiles of these systems were obtained by measuring their fluorescent anisotropy under pressure. The mid-disassembly pressure of rod minifilaments at 0.4 mg/mL concentration was 430-490 bar. However, dissociation of two helical strands of rod molecules occurred at a much higher pressure, with a mid-disassembly pressure of 1300 bar at this concentration. These results indicate that the intramolecular interactions occurring between two alpha-helical chains of a rod molecule are much more stable under pressure than the intermolecular interactions that occur among rod molecules in a minifilament. The regions in the rod molecules involved in filament assembly were investigated through usage of both the intrinsic fluorescence of tryptophan residues and the extrinsic fluorescence of 6-acryloyl-2-(dimethylamino)naphthalene (acrylodan) labeled cysteine residues. The blue spectral shifts upon minifilament formation suggest the participation of both light meromyosin (LMM) and subfragment-2 (S-2) regions of myosin rods in the filament formation. Profiles of thermal unfolding of myosin rod molecules and rod minifilaments were obtained by circular dichroism measurement. The multiple transitions exhibited upon unfolding profiles indicated the presence of more than one structural domain, each correlating with a cooperative transition. The domain transitional temperatures were found to be 1-4 degrees C higher for rods in minifilaments than those for rod molecules in a solution of similar ionic composition, indicating that all structural domains are involved in filament assembly. Furthermore, the domain transitional temperatures for rod molecules in a buffer containing 0.6 M NaCl were 6-8 degrees C higher than those for rod molecules in 5 mM sodium pyrophosphate buffer, suggesting that each structural domain of a rod molecule becomes stabilized at 0.6 M NaCl solution.

Animals↗
PubMed1994

Effects of denaturant and pressure on the intrinsic fluorescence of titin.

The intrinsic fluorescence of titin was analyzed in this present study. The average fluorescence wavelength of titin was 17 nm shorter than that of tryptophan in water, indicating that tryptophans in titin are not completely exposed to solvent. Guanidine hydrochloride (GdmCl) induced a red spectral shift of 17 nm, a decrease of total intensity of 33%, an increase of spectral bandwidth, and a decrease of anisotropy of 59%. The GdmCl concentration dependence of these fluorescence parameters indicated a two-state transition phenomenon with a transition midpoint at 2.6 M. The free energy change associated with this transition is in the range of 3-3.5 kcal/mol/domain, assuming that titin domains are unfolded independently. The anisotropy value also decreased 69% upon application of hydrostatic pressure up to 2.4 kbar, similar to the situation of GdmCl denaturation. However, the spectral red shift was 3.7-nm at a pressure of 2.4 kbar, indicating that the pressure-altered conformation of titin at 2.4 kbar is distinct to the GdmCl-denatured conformation. Pressure above 2 kbar apparently generated a flexible hydrophobic pocket for tryptophan residues of titin.

Animals↗
PubMed1994

Use of an air medical helicopter in a trauma prevention program.

Trauma is acknowledged as the leading cause of death in the United States in those under 45 years old, with the automobile being particularly lethal and costly. Preventive teaching is a component of any injury reduction program, and health care providers are becoming more actively involved in such efforts. The Mercy Air Ambulance medical team has developed a mock vehicle-collision demonstration, which is staged at area high schools shortly before graduation. The program is a joint effort of several agencies and services. It stimulates the arrest of the responsible driver, the rescue and subsequent air medical transport of two injured students and the death of a fourth student. Not only does this program educate the students in an entertaining fashion, but it results in valuable training for the multiple agencies and individuals who participate in the actual response to motor-vehicle collisions.

Accidents, Traffic↗
PubMed1994

Use of home health services by elderly persons with cognitive impairment.

Individuals with cognitive impairment are at high risk for institutionalization; thus, they may benefit from the support provided by home health services. The authors studied a cohort of elderly persons admitted to a home health agency, after first assessing them for cognitive impairment. Comparisons were made between cognitively impaired and cognitively intact individuals. Significant differences in the volume and type of services used were found. Management issues for home health agencies are raised.

Aged↗
PubMed1994

Abundance of a restricted fetal B cell repertoire in marrow transplant recipients.

Patients undergoing bone marrow transplantation are humorally immunodeficient for one or more years post-transplant. This immunodeficiency could be partially caused by B cell repertoire restriction similar to that observed in ontogeny. To test this idea, the abundance of rearranged genomic segments bearing five variable heavy chain (VH) genes was compared in patients at several timepoints post-transplant and in immunologically normal neonates, infants and adults. The genes evaluated in the study (VH6, VH4-58p2, VH3-56p1, VH3-20p1 and VH3-13-2) were selected from those commonly utilized by fetal B cells. The assay employed quantitative PCR and oligonucleotide hybridization detection under conditions designed to detect relatively unmutated forms of these genes. In blood B cells from early post-transplant (2-5 months) patients, these VH genes were markedly overutilized compared with normal adults. B cells from late post-transplant (6-21 months) patients and from normal neonates and infants also overutilized these genes; however, to a lesser degree than early post-transplant B cells. The data suggest that, as in ontogeny, the B cell repertoire is strikingly restricted to fetal-type VH genes early post-transplant, and may become normal only very late (years) post-transplant.

Adult↗
PubMed1994

Perceptions of collaborative practice between Navy nurses and physicians in the ICU setting.

BACKGROUND: Despite strong evidence for the benefits of collaborative practice between nurses and physicians, this model remains the exception rather than the rule. OBJECTIVES: To examine the extent to which Navy nurses and physicians perceive that collaborative practice exists in the ICU, and to examine the difference in perceived use of collaborative practice by Navy nurses and physicians in the ICU. METHODS: Ninety nurses and 49 physicians working in ICUs at the Navy's four teaching hospitals and aboard the Navy's two hospital ships deployed in Southwest Asia were surveyed using the Collaborative Behavior Scale-Part I and the Collaborative Practice Scales. RESULTS: There was a significant difference between nurses' and physicians' perceptions of collaborative practice behavior. Physicians reported that collaborative practice behavior existed to a greater extent than did nurses in the study. There was no significant difference between nurses' and physicians' perceived use of collaborative practice behavior. CONCLUSIONS: Navy ICU nurses and physicians perceived that they were involved in collaborative practice behavior at a moderate level. Physicians, however, reported perceiving collaborative practice to a greater extent than did nurses. Further research, in different populations, is required to test the theorized constructs of the instruments used to measure perceptions of collaborative practice behavior in this study.

Attitude of Health Personnel↗
PubMed1993

The effect of calcium phosphate ceramic composition and structure on in vitro behavior. I. Dissolution.

Synthetic calcium phosphate ceramic (CPC) surfaces can be transformed to a biological apatite through a sequence of reactions which include dissolution, precipitation, and ion exchange. By virtue of the reactions being material-dependent, it is important to determine parametric rate effects. In this study we focused on the effect of stoichiometry and crystal structure of CPCs on the dissolution kinetics. Monophase, biphase, and multiphase CPCs with a Ca/P ratio equal to or greater than 1.5 were studied. The experiments were performed in a calcium- and phosphate-free Tris buffer solution at pH 7.3. The dissolution behavior of the CPCs studied was found to vary over a wide range. The dissolution rate of the monophase CPCs increased in the order of stoichiometric hydroxyapatite, calcium deficient hydroxyapatite, oxyhydroxyapatite, beta-tricalcium phosphate, alpha-tricalcium phosphate, and tetracalcium phosphate. Dissolution of biphase and multiphase CPCs increased prorated the concentration of more soluble component.

Biocompatible Materials↗
PubMed1993

Metastatic clear-cell hidradenocarcinoma of the vulva.

Clear-cell hidradenocarcinoma is a malignant tumor of sweat gland origin. It is most often found on the trunk, head, and extremities. This case report describes a rare occurrence of this tumor on the vulva of a young woman. The discovery of metastatic disease reflects the potentially aggressive nature of this tumor.

Adenocarcinoma↗