Biomedical subjects

J L Evans

Publications and source records attributed to J L Evans.

At least 19 recordsLinked to original sources

PubMed1998

Field trial of endotracheal intubation by basic EMTs.

STUDY OBJECTIVE: The 1994 basic-EMT (EMT-B) curriculum recommended teaching EMT-Bs the skill of endotracheal intubation. In this study we assessed the success and complication rates of endotracheal intubations in the field by EMT-Bs. METHODS: We conducted a prospective clinical trial over a period of 28 months in an urban out-of-hospital EMS system. Four first-responder EMT-B engine companies with paramedic backup received 10 hours; intubation training in three sessions spread over at least 2 weeks. The training module was similar to that of the 1994 EMT-B curriculum and included at least 10 intubations on manikins. The EMTs used manikins with closed chest cavities to learn assessment of endotracheal-tube placement. Patients were eligible for intubation by the EMTs if they were apneic and older than 15 years. We calculated 95% confidence interval (CIs) for intubation success rates. RESULTS: Sixty-six EMT-Bs passed the training examinations and were authorized to perform intubation in the field. Endotracheal intubation was attempted by EMTs in 103 patients; the attempt was successful in 53 (95% CI, 42% to 61%). All patients who were not intubated by EMT-Bs were intubated by paramedics, with the exception of six cases. One attempt at intubation was made in 52 patients, two attempts in 44, and three in 7. Three unrecognized esophageal intubations occurred. CONCLUSION: EMT-Bs trained in a short course successfully intubated about half the patients they encountered in this study. This low intubation success rate calls into question the validity of the endotracheal-intubation training module in the 1994 EMT-B national curriculum.

Aged↗

PubMed1997

Response latency and verbal complexity: stochastic models of individual differences in children with specific language impairments.

Within-subject statistical modeling techniques were employed to investigate individual differences in the extent to which two possible indicators of processing time predicted changes in utterance complexity during spontaneous discourse for 10 children ages 7;1 to 10;1 with specific language impairments (SLI) who differed in receptive language abilities. The two indicators of processing time that were modeled were response latency and the use of a specific discourse marker (Verbal Pause) that provided children with additional time to respond. Longer response latencies were not a strong predictor of increased utterance length for any of the children. However, results indicated that children with better receptive skills used substantially more verbal pauses than children with both expressive and receptive deficits and that the use of these pauses was a strong predictor of increased utterance length for children with better comprehension skills.

Adult↗

PubMed1996

Accurate three-dimensional reconstruction of intravascular ultrasound data. Spatially correct three-dimensional reconstructions.

BACKGROUND: The geometrical accuracy of conventional three-dimensional (3D) reconstruction methods for intravascular ultrasound (IVUS) data (coronary and peripheral) is hampered by the inability to register spatial image orientation and by respiratory and cardiac motion. The objective of this work was the development of improved IVUS reconstruction techniques. METHODS AND RESULTS: We developed a 3D position registration method that identifies the spatial coordinates of an in situ IVUS catheter by use of simultaneous ECG-gated biplane digital cinefluoroscopy. To minimize distortion, coordinates underwent pincushion correction and were referenced to a standardized calibration cube. Gated IVUS data were acquired digitally, and the spatial locations of the imaging planes were then transformed relative to their respective 3D coordinates, rendered in binary voxel format, resliced, and displayed on an image-processing workstation for off-line analysis. The method was tested by use of phantoms (straight tube, 360 degrees circle, 240 degrees spiral) and an in vitro coronary artery model. In vivo feasibility was assessed in patients who underwent routine interventional coronary procedures accompanied by IVUS evaluation. Actual versus calculated point locations were within 1.0 +/- 0.3 mm of each other (n = 39). Calculated phantom volumes were within 4% of actual volumes. Phantom 3D reconstruction appropriately demonstrated complex morphology. Initial patient evaluation demonstrated method feasibility as well as errors if respiratory and ECG gating were not used. CONCLUSIONS: These preliminary data support the use of this new method of 3D reconstruction of vascular structures with use of combined vascular ultrasound data and simultaneous ECG-gated biplane cinefluoroscopy.

Blood Vessels↗

PubMed1996

SLI subgroups: interaction between discourse constraints and morphosyntactic deficits.

A performance-based model was employed to investigate the impact of discourse demands on the pattern of morphosyntactic deficits exhibited by children with Specific Language Impairments (SLI). The pattern of grammatical errors varied with respect to discourse demands for children with good receptive language abilities but remained stable and independent of changes in discourse demands for children with both expressive and receptive deficits. These findings suggest distinct deficit profiles for subgroups of children with SLI differing in receptive language abilities that are not evident when syntactic skills are investigated outside the context of ongoing spontaneous discourse.

Child↗

PubMed1995

Transgenic superoxide dismutase mice differ in opioid-induced analgesia.

Autoradiographic data from transgenic mice carrying the human Cu/Zn-superoxide dismutase gene demonstrate an increase in mu-opioid receptor concentration in dopaminergic-related areas and the central grey area. The relative potencies of mu-, delta- and kappa-opioid receptor agonists to induce antinociception in heterozygous and homozygous superoxide dismutase transgenic mice as well as four inbred strains were assessed to determine the functional significance of the increased receptor concentration. Increased superoxide dismutase activity results in an increased sensitivity to mu-agonists in a gene dosage-dependent manner. SOD/Tg/hom mice were less sensitive to the delta-agonist than were SOD/Tg/het mice. The superoxide dismutase transgene did not affect kappa-opioid receptor agonist sensitivity. These data suggest that delta-opioid receptors are not regulated in the same manner as mu-opioid receptors and that kappa-opioid receptors are unaffected by superoxide dismutase activity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1995

The effects of wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase, on insulin-stimulated glucose transport, GLUT4 translocation, antilipolysis, and DNA synthesis.

PI 3-kinase, an enzyme that selectively phosphorylates the 3-position of the inositol ring, is acutely activated by insulin and other growth factors. The physiological significance of PI 3-kinase activation and, more specifically, its role in insulin action is an area under intense investigation. In this study, we have examined the role of PI 3-kinase activation in mediating selected metabolic and mitogenic effects of insulin employing the fungal metabolite wortmannin, a potent inhibitor of PI 3-kinase activity. In isolated rat and cultured 3T3-L1 adipocytes, wortmannin inhibited insulin-stimulated glucose transport (IC50 = 9 nM) without a significant effect on basal transport. Insulin-stimulated translocation of GLUT4 in isolated rat adipocytes was markedly inhibited by wortmannin. Wortmannin had no effect on either basal or insulin-stimulated glucose utilization in L6 myocytes, a skeletal muscle cell line in which GLUT1 is the predominant transporter isoform. Wortmannin also partially antagonized the antilipolytic effect of insulin on adenosine deaminase-stimulated lipolysis in isolated rat adipocytes. Furthermore, wortmannin caused a significant reduction in insulin-stimulated DNA synthesis in Fao rat hepatoma cells. We conclude that PI 3-kinase activation is necessary for maximum insulin-stimulated glucose transport, translocation of GLUT4, antilipolysis and DNA synthesis.

3T3 Cells↗

PubMed1994

Expression of human GLUT4 in mice results in increased insulin action.

Glucose metabolism was evaluated in transgenic mice expressing the human GLUT 4 glucose transporter. Fed GLUT 4 transgenic mice exhibited a 32% and 56% reduction in serum glucose and insulin and a 69% and 33% increase in non-esterified fatty acid and lactate levels, respectively. Transgenic mice exhibited a significant increase in whole-body glucose disposal during a euglycaemic-hyperinsulinaemic clamp. Insulin-stimulated glucose uptake in isolated soleus muscles and adipocytes was greater in transgenic compared to control mice due to increased basal glucose uptake. Transgenic mice displayed increased glycogen levels in liver and gastrocnemius muscle, and increased insulin-stimulated 14C-glycogen accumulation in isolated soleus muscle. We conclude that over-expression of the GLUT 4 glucose transporter in mice results in 1) an increase in whole-body glucose disposal and storage, and 2) an increase in both basal and insulin-stimulated glucose uptake and disposal in vitro. These changes resulted in the reduction of serum glucose and insulin levels. These results provide direct evidence that glucose transport (and GLUT 4 per se) plays a significant role in regulating whole-body glucose homeostasis. Additionally, these data support the idea that pharmacological strategies directed at increasing the expression of GLUT 4 protein may have beneficial (hypoglycaemic) effects in the diabetic state.

Adipocytes↗

PubMed1994

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, I. Initial studies.

BACKGROUND: Intravascular ultrasound (IVUS) of arteries is limited by the inability of current instruments to visualize beyond the catheter tip. We have developed a prototype 4-mm-diameter forward-viewing IVUS catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif) that has the ability to provide B-mode cross-sectional ultrasound data for a distance of up to 2 cm distal to the catheter tip. METHODS AND RESULTS: To study the utility of this device, a 20-MHz forward-viewing IVUS catheter was used to examine 13 arterial segments (5 human femoral arteries, 1 human carotid artery, 7 canine arteries) in vitro and 1 phantom. After imaging, all data were compared with histology (Histo). In all cases, the IVUS catheter provided forward-viewing images corresponding to the arterial geometry and demonstrated vascular landmarks and atherosclerotic lesions. There was a good correlation between Histo-determined luminal diameters (LD) and IVUS-determined diameters for a distance of 14 mm ahead of the catheter tip: IVUS LD = 1.0 Histo LD + 1.3 (r = .87). CONCLUSIONS: These preliminary data suggest that a forward-viewing IVUS catheter is feasible, accurate, and useful for evaluation of arterial geometry distal to the catheter tip.

Angiography↗

PubMed1994

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, II. Three-dimensional reconstruction and display of data.

BACKGROUND: Current intravascular ultrasound (IVUS) catheters provide transverse imaging at the level of the ultrasound transducer. This limits imaging to large-diameter segments without critical atherosclerotic narrowings. We have developed a prototype 20-MHz forward-viewing IVUS catheter that provides two-dimensional sector imaging distal to the catheter tip. A present limitation of this technique is that the catheter must be manually rotated to obtain multiple longitudinal views required to integrate the segment into a three-dimensional matrix. To overcome this, we have developed an algorithm that reconstructs these multiple two-dimensional forward-viewing IVUS images into a three-dimensional matrix for more complete depiction of the segment distal to the ultrasound catheter. This algorithm allows display and multidimensional slicing of the three-dimensional reconstruction. METHODS AND RESULTS. To test our algorithms, five arterial segments (three canine aortas, two human femoral arteries) were evaluated in vitro. In each segment, 36 forward-viewing longitudinal slices were collected, digitized, processed, and reoriented to produce a three-dimensional reconstruction (3DR) matrix. The matrix data were sliced into parallel transverse sections and compared with morphometric interpretation of histological sections (Histo). As a result, image data could be reconstructed for a distance of 2.0 cm ahead of the catheter. 3DR easily demonstrated wall and luminal morphology and provided transverse IVUS images comparable to the histological specimens. A good correlation was noted between Histo- and 3DR-determined luminal diameters (LD) and luminal areas: 3DR LD = 1.4 Histo LD-0.4, r = .86; 3DR LD = 0.7 +/- 0.20 cm (mean +/- SD); and Histo LD = 0.7 +/- 0.13 cm. CONCLUSIONS: These preliminary data demonstrate the feasibility of 3DR of forward-viewing IVUS data. This method allows rapid, detailed analysis of diseased arterial segments previously unavailable with standard IVUS and may permit better targeting of interventional techniques.

Animals↗

PubMed1994

Effects of diet acidity and protein level or source of calcium on the performance, gastrointestinal content measurements, bone measurements, and carcass composition of gilt and barrow weanling pigs.

A total of 228 crossbred weanling pigs (average age of 25 d and BW of 6.44 kg) were used in two trials to evaluate the responses to sex, diet acidity, protein level, and source of calcium on the performance, gastrointestinal digesta measurements, bone measurements, and carcass composition. Diet acidity was manipulated by varying the sources of supplemental phosphorus in the diets. Trial 1 (5 wk) was conducted as a 2 x 3 x 2 factorial to evaluate sex (gilts and barrows), diet acidity (pH 5.9 and .90% P, pH 6.1 and .63% P, and pH 6.9 and .63% P), and level of protein (16 and 22% CP). In Trial 2 (6 wk), diet acidity (pH 5.5, 5.9, and 6.8, all with .7% P) and Ca sources (CaCO3 and CaSO4) were used with gilts and barrows. The sex x diet acidity interactions were significant for ADG in both trials. Barrows seemed to respond to both the more acidic diets and the buffered phosphate diets even though the pH was less acidic than that of the unbuffered diets. Gilts responded only to the more acidic diets. In Trial 1, gilts ate more and grew faster (P < .05) than barrows, but no sex effects on performance were observed in Trial 2. Pigs fed 22% CP diets grew faster (P < .001) and more efficiently (P < .001) than did pigs fed 16% CP diets, but protein level x diet acidity and protein level x sex interactions were not significant. Stomach digesta DM, pH, and titration value were not consistently influenced by sex and diet acidity in Trials 1 and 2, by protein level in Trial 1, and by calcium source in Trial 2. Only the sex x diet acidity interaction for stomach DM tended to be significant in both trials; gilts fed the less acidic diets had the lowest DM, whereas barrows fed the more acidic diets had the lowest DM values. Although not significant in every case in both trials, bone (average of metacarpal and metatarsal) volume was lower and specific gravity and shear stress values were higher for gilts than for barrows. Pigs fed 16% CP diets had higher specific gravity (P < .05) and stress (P < .06) values than pigs fed 22% CP diets. A protein level x diet acidity interaction (P < .03) for stress suggested that pigs fed 22% CP diets were unaffected by diet acidity, whereas pigs fed 16% CP had the highest stress values when fed the more acidic diet and the lower P level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Secretion of radioactivity in breast milk following administration of 99Tcm-MAG3.

Measurements were made of the fraction of injected radioactivity which was secreted in breast milk following 99Tcm-MAG3 dynamic renal scans of two nursing mothers. The activity concentration in the milk expressed at different times after injection was found to decrease monoexponentially, with effective half-lives of 3.2 and 4.0 h. Two models were applied to each set of data and predicted an overall mean infant effective dose equivalent per unit administered activity of 2.9 muSv MBq-1 and maximum of 4.5 muSv MBq-1. The results demonstrated that it was not essential to interrupt breast feeding following administration of 100 MBq 99Tcm-MAG3 for a dynamic renal scan. If a renal perfusion scan is performed using greater activities of 99Tcm-MAG3, the mother should interrupt feeding and not resume until measurements on her expressed milk samples indicate that the effective dose equivalent to the infant will be less than 1 mSv. However, it was noted that a considerably lower radiation dose to the infant could be achieved by using 99Tcm-DTPA. Therefore, it was concluded that whenever clinically appropriate 99Tcm-DTPA should be used for both types of renal investigations of breast-feeding mothers.

Female↗

PubMed1993

Pragmatics and SLI: within-group variations in discourse behaviors.

Selected discourse behaviors of children with specific language impairment (SLI) presenting expressive (E:SLI) or combined expressive-receptive deficits (E-R:SLI) were compared to each other and to chronological age-mates and younger mean length of utterance (MLU)-matched children with normal-language skills. The two SLI subgroups varied from each other on specific measures of turn-taking and cohesion. These findings imply the need for future normative work with SLI subgroups differing in receptive skill, and indicate that, in the interim, pragmatic research with this population will need to consider potential effects of receptive language status when interpreting variations in outcomes for discourse-based variables.

Child↗

PubMed1992

Acetyl-CoA carboxylase in Reuber hepatoma cells: variation in enzyme activity, insulin regulation, and cellular lipid content.

Reuber hepatoma cells are useful cultured lines for the study of insulin action, lipid and lipoprotein metabolism, and the regulation of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of fatty acid biosynthesis. During investigations in different clonal lines of these cells, we have uncovered marked intercellular variability in the activity, enzyme content, and insulin regulation of ACC paralleled by differences in cellular neutral lipid (triglyceride) content. Two contrasting clonal lines, Fao and H356A-1, have been studied in detail. Several features distinguish these two lines, including differences in ACC activity and enzyme kinetics, the content of the two major hepatic ACC isozymes (Mr 280,000 and 265,000 Da) and their heteroisozymic complex, the extent of ACC phosphorylation, and the ability of ACC to be activated on stimulation by insulin and insulinomimetic agonists. As studied by Nile Red staining and fluorescence-activated cell sorting, these two lines also display marked differences in neutral lipid content, which correlates with both basal levels of ACC activity and inhibition of ACC by the fatty acid analog, 5-(tetradecyloxy)-2-furoic acid (TOFA). These results emphasize the importance of characterization of any particular clonal line of Reuber cells for studies of enzyme regulation, substrate metabolism, and hormone action. With respect to ACC, studies in contrasting clonal lines of Reuber cells could provide valuable clues to understanding both the complex mechanisms of intracellular ACC regulation in the absence and presence of hormones and its regulatory role(s) in overall hepatic lipid metabolism.

Acetyl-CoA Carboxylase↗

PubMed1992

Language sample collection and analysis: interview compared to freeplay assessment contexts.

Spontaneous language samples elicited during freeplay and interview contexts were compared for 10 children who were specifically language impaired (SLI). Clinician-child videotaped interactions were analyzed for both structural and conversational behaviors. The results indicated that the interview was a reliable and valid assessment context, eliciting the same profile of behaviors as the freeplay context without altering diagnostic classifications. Most behaviors occurred significantly more often during the interview than during the freeplay context, indicating further that interviews are an efficient language sampling alternative for assessment purposes with elementary school-aged children with language disorders.

Child↗

PubMed1992

HLA-DR and DQ matching by DNA restriction fragment length polymorphism methods and the outcome of mixed lymphocyte reaction tests in unrelated bone marrow donor searches. The IMUST Study.

The use of DNA restriction fragment length polymorphism (DNA-RFLP) typing for HLA-DR and DQ genes was assessed in 96 patients who were HLA-A,B and DR matched by serology with one or more potential unrelated marrow donors (UD). Two hundred recipient-donor pairs from 10 transplant centres in the UK were studied. DNA-RFLP revealed serological errors in HLA-DR typing and identified additional recipient-donor mismatches. Of the 200 allegedly serologically matched pairs, 55 (28%) were mismatched for HLA-DR and/or DQ by DNA-RFLP typing. Of the 200 pairs, 68 (34%) mixed lymphocyte reactions (MLR) were negative and 132 (66%) positive. There was a significant correlation between DNA-RFLP defined mismatch and MLR positivity. However quantitative studies revealed no trend towards increasing MLR relative response index (RRI) with cumulative RFLP defined mismatch (i.e. for DR plus DQ compared with DR or DQ alone). RFLP matching for HLA-DR and DQ failed to predict a negative MLR. The RRI in the graft-versus-host direction was greater in RFLP matched pairs who carried HLA-DR4 than in matched pairs lacking DR4, suggesting that failure of RFLP to characterize DR4 subtypes was one reason why routine prediction of a negative MLR was not possible. Despite these limitations we have shown that DNA-RFLP is a reliable method for HLA-DR, DQ typing in routine UD searches in diverse clinical centres. By reducing the number of UD tested in MLR, RFLP typing can substantially reduce the work involved in donor selection.

Bone Marrow Transplantation↗

PubMed1992

Early language and communicative abilities of children with periventricular leukomalacia.

Ten 2-year-old children with periventricular leukomalacia (PVL), a brain injury associated with prematurity, were evaluated using language samples. Five children scored less than 80 on cognitive testing (delayed). Five children with this disorder and normal cognitive scores were assessed at two ages, matched with the delayed group on CA and developmental level. The delayed group produced significantly fewer lexical tokens and spontaneous verbal utterances than did the CA-matched group. No significant differences were observed between the delayed group and either comparison group on other measures of lexicon, grammar, or communication. The data demonstrate a relation between cognitive abilities and measures of verbal productivity in children with PVL.

Child↗

PubMed1991

Turn exchange behaviors of children with normally developing language: the influence of gender.

The turn exchanges of normally developing 8-year-old boys and girls were examined within adult-child dyadic interaction. Videotaped language samples were analyzed for gender differences in the children's production of simultaneous and nonsimultaneous speech. The results indicated no gender differences for nonsimultaneous turn exchange behaviors but significant differences in the overlap subtypes and simultaneous resolution patterns between the boys and the girls. Sex of the adult partner influenced the negotiation and ultimate length of the children's turns. The children's gender differences were consistent with the adult literature that characterizes men as more assertive conversationally than women.

Adult↗

PubMed1991

Effects of dietary pH and phosphorus source on performance, gastrointestinal tract digesta, and bone measurements of weanling pigs.

Crossbred pigs (n = 144, average age and weight = 28 +/- 3 d, 7.5 kg) were used in two 6-wk trials to assess the effects of dietary pH and P source on growth performance, gastrointestinal digesta pH and chloride ion concentration (Cl-), and bone characteristics. Treatments were randomly allotted within blocks (based on weight within gender) to a 3 x 2 factorial arrangement with three dietary pH levels (5.4, 6.0, and 6.7) and two P sources: dicalcium phosphate (DCP) and defluorinated phosphate (DFP). Pigs fed the pH 6.7 diet had reduced ADG (P less than .01) and average daily feed intakes (ADFI; P less than .001) during wk 1 to 3 and overall compared with pigs fed the pH 6.0 diet, but ADG and ADFI were not affected when the pH 5.4 diet was fed. There was a dietary pH x P source interaction (P less than .05) for ADFI. Pigs had decreased ADFI as dietary pH was increased from 6.0 to 6.7 for both DCP and DFP, but ADFI was similar for the pH 6.0 and 5.4 diets with DFP, whereas ADFI was greater for the pH 5.4 diet with DCP. Dietary pH did not influence ADFI:ADG ratio (F:G; P greater than .05), and P source had no effect (P greater than .05) on either ADG, ADFI, or F:G.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗