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Biomedical subjects

M Jones

Publications and source records attributed to M Jones.

At least 325 records · Page 18Linked to original sources
PubMed1998

Effect of continuous positive airway pressure on forced expiratory flows in infants with tracheomalacia.

Continuous positive airway pressure (CPAP) is used to minimize airway collapse in infants with tracheomalacia. Forced expiratory flows (FEFs) at functional residual capacity (FRC) increase with increasing CPAP in infants with tracheomalacia, and it has been suggested that CPAP prevents airway collapse by "stenting" the airway open. Since FEF is greater at higher than at lower lung volumes, we evaluated whether the increase in flow measured at FRC (V FRC) with CPAP could be explained by the increase in FRC with CPAP. We measured full FEF-volume curves at CPAP levels of 0, 4, and 8 cm H2O in six infants with tracheomalacia and five healthy control infants. In both groups of infants, FVC did not change with CPAP; however, inspiratory capacity (IC) decreased and thus FRC increased with increasing CPAP. FEFs at FRC increased with increasing levels of CPAP; however, the FEFs at 50% and 75% of expired volume were not different for the three levels of CPAP for both groups of infants. Our finding that FEFs measured at the same lung volumes did not differ for the different levels of CPAP indicates that CPAP affects forced flows primarily by increasing lung volume.

Forced Expiratory Flow Rates↗
PubMed1998

Violence and aggression in psychiatric units.

OBJECTIVE: To help predict aggressive and violent behaviors, the frequency and types of these behaviors in acute psychiatric inpatient settings were examined, and potential interactions between staffing and patient mix and rates of the behaviors were explored. METHODS: Data on violent incidents were gathered prospectively in three adult acute psychiatric units in a general hospital and two units in a primary psychiatric hospital in Sydney, Australia. Staff recorded violent and aggressive incidents, which were ranked on an 8-level scale. They also completed weekly reports of staffing levels and patient mix. Poisson regression analysis was used to calculate relative rates, 95 percent confidence intervals, and p values. RESULTS: A total of 1,289 violent incidents were recorded over a seven-month period. Based on the scale, 58 percent of the incidents were serious. Seventy-eight percent were directed toward nursing staff. Complex relationships between staffing, patient mix, and violence were found. Relative risk increased with more nursing staff (of either sex), more nonnursing staff on planned leave, more patients known to instigate violence, a greater number of disoriented patients, more patients detained compulsorily, and more use of seclusion. The relative risk decreased with more young staff (under 30 years old), more nursing staff with unplanned absenteeism, more admissions, and more patients with substance abuse or physical illness. In total these factors accounted for 62 percent of the variance in violence. CONCLUSIONS: Violent incidents in psychiatric settings are a frequent and serious problem. Incidents appear to be underreported, and the seriousness of an incident does not guarantee it will be reported.

Adult↗
PubMed1998

Repetitively violent patients in psychiatric units.

OBJECTIVE: Violent incidents in inpatient psychiatric settings were examined among a group of repeatedly violent patients to better understand the clinical and occupational health significance of repeated violence. METHODS: Data on violent incidents were collected prospectively over seven months in five psychiatric units in Sydney, Australia. Recidivist patients--those responsible for more than 20 incidents of violence or aggression--and nonrecidivist violent patients were compared in terms of the nature of the incidents, warning signs, and staff responses to violence. RESULTS: Of the 174 patients involved in violent incidents, 20 (12 percent) were recidivists. These patients accounted for 69 percent of the 752 violent incidents identified. Recidivists were significantly older than nonrecidivist patients. Compared with nonrecidivists, the men recidivists were more likely to have an organic brain syndrome, and the women recidivists were more likely to have a personality disorder. When a recidivist patient was violent, staff members' response was significantly less likely to include institutional mechanisms for dealing with violence, such as contacting occupational health and safety officers, completing injury notification forms, and notifying police. Violence occurred among recidivists despite their giving more warning signs than nonrecidivists, suggesting that recidivists' threats were not taken seriously by staff, perhaps reflecting demoralization in the face of repeated violence. CONCLUSIONS: Even though this study focused only on serious incidents and defined recidivism narrowly, it found that recidivism of violence and aggression among psychiatric patients was a serious problem. The relative lack of response by staff members to the violent acts of recidivist patients is of concern.

Aggression↗
PubMed1998

Cognitive performance in recreational users of MDMA of 'ecstasy': evidence for memory deficits.

Cognitive task performance was assessed in three groups of young people: 10 regular users of 3,4-methylenedioxymethamphetamine (MDMA) who had taken 'ecstasy' 10 times or more; 10 novice MDMA users who had taken 'ecstasy' one to nine times; and 10 control subjects who had never taken MDMA. A computerized battery of cognitive tasks (Cognitive Drug Research system) was undertaken on a day when subjects were drug free. Performance on the response speed and vigilance measures (simple reaction time, choice reaction time, number vigilance), was similar across the three subgroups. However on immediate word recall and delayed word recall, both groups of MDMA users recalled significantly less words than controls. Animal research has shown that MDMA can lead to serotonergic neurodegeneration, particularly in the hippocampus and frontal cortex. Although the design of this study was far from ideal, these data are consistent with other findings of memory decrements in recreational MDMA users, possibly caused by serotonergic neurotoxicity.

Adolescent↗
PubMed1998

Lunar cycles and violent behaviour.

OBJECTIVE: It is commonly believed that the full moon exerts an influence on violence and aggression in psychiatric settings. The literature to date is contentious. This study used a robust methodology to examine the hypothesis that there was an increased frequency of violent and aggressive behaviour among hospitalised psychiatric clients at the time of the full moon. METHOD: Prospective data were collected in five inpatient psychiatric settings across the Northern Sydney Area Health Service. Morrison's hierarchy of violence and aggression was used to rate behaviour. Lunar phases were clearly defined and Poisson regression used to examine relationships between lunar phase and violence. Extraneous temporal variation was considered. RESULTS: No significant relationship was found between total violence and aggression or level of violence and aggression and any phase of the moon. CONCLUSION: Future research could profitably examine the implications of a belief in the lunar effect among health workers in the face of evidence that no relationship exists between violence, aggression and the lunar cycle.

Adult↗
PubMed1998

A method for estimating aortic regurgitant effective orifice area by digital Doppler color flow mapping.

BACKGROUND AND AIMS OF THE STUDY: Although non-invasive assessment of the severity of aortic regurgitation (AR) is important, quantitative evaluation of AR can be difficult in clinical settings. Most Doppler echocardiographic methods have been compared with angiographic grading of AR severity. However, while aortic angiography is used widely for grading AR severity, the method is only semi-quantitative. A computed semi-automatic digital color Doppler method has recently been described for calculating stroke volume and cardiac output. The study aim was to develop a method of evaluating AR severity by using a digital automated color Doppler method (ACM) along with continuous wave (CW) Doppler for estimating aortic regurgitant effective orifice area. METHODS: A total of 22 different hemodynamic conditions were studied in six sheep. Regurgitant volumes (RV) were determined by electromagnetic flowmetry (EM) and by ACM. AR effective orifice areas (EOAs) were determined by dividing each of the RVs by the time integrals of the AR continuous wave velocities. AR EOAs by ACM were compared with those obtained by EM and with other EM indices of regurgitant severity. ACM was accurate for quantifying AR EOAs (r = 0.96). RESULTS AND CONCLUSIONS: Calculated AR EOA correlated well with peak AR flow and regurgitant fraction by EM. The combined ACM/CW Doppler method can be useful for estimating non-invasively the aortic regurgitant EOA and for evaluating the severity of AR.

Anatomy, Cross-Sectional↗
PubMed1998

Bacterial flora in the duodenum of healthy cats, and effect of dietary supplementation with fructo-oligosaccharides.

OBJECTIVE: To investigate changes in the duodenal flora of healthy cats over time, and evaluate the effect of dietary supplementation with fructo-oligosaccharides (FOS). ANIMALS: 12 healthy, barrier-maintained, specific-pathogen-free cats. PROCEDURE: Duodenal juice for bacteriologic examination was collected via oral endoscopy 5 times from each cat over a 32-week period. Cats were allotted randomly to 2 groups, and a crossover design study, during which they were fed either a replete dry (basal) diet or, for 12 consecutive weeks, basal diet supplemented with 0.75% FOS, was done. Samples (3 from cats fed the basal and 2 from cats fed the FOS diet) were collected for a minimum of 6 weeks after commencement of feeding, and a minimum of 6 weeks apart. RESULTS: Mean aerobic, anaerobic, and total bacterial counts did not differ significantly among sample collection times. After pooling of the results, mean (+/- SD) log10 colony-forming units (CFU) of aerobic, anaerobic, and total bacteria/ml were 5.5 +/- 1.1, 4.8 +/- 1.0 and 5.6 +/- 1.1, respectively. However, individual cats had considerable variation in counts: mean (range) intraindividual coefficients of variation were: 19.0 (6.1 to 34.2), 19.9 (4.8 to 35.5), and 18.1 (5.5 to 32.6)%, respectively. In 1 cat, total bacterial count varied between < 3.0 and 6.3 CFU/ml. Bacterial flora varied qualitatively: only Enterococcus faecalis, Clostridium perfringens, Bacteroides, Pasteurella, and Streptococcus spp, and unidentified gram-negative (aerobic) rods were present in > 50% of the samples. CONCLUSIONS: Wide quantitative and qualitative variation in the duodenal flora of healthy cats was observed over time, which was not affected by dietary supplementation with FOS.

Animal Feed↗
PubMed1997

Direct measurement of three-dimensionally reconstructed flow convergence surface area and regurgitant flow in aortic regurgitation: in vitro and chronic animal model studies.

BACKGROUND: Evaluation of flow convergence (FC) with two-dimensional (2D) imaging systems may not be sufficiently accurate to characterize these often asymmetric, complex phenomena. The aim of this study was to validate a three-dimensional (3D) method for determining the severity of aortic regurgitation (AR) in an experimental animal model. METHODS AND RESULTS: In six sheep with surgically induced chronic AR, 20 hemodynamically different states were studied. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary electromagnetic flow meters. Video composite data of color Doppler flow mapping images were transferred into a TomTec computer after computer-controlled 180 degrees rotational acquisition. Direct measurement of the 3D reconstructed FC surface areas as well as measurements of FC areas estimated with 2D methods with hemispherical and hemielliptical assumptions were performed, and values were multiplied by the aliasing velocity to obtain peak regurgitant flow rates. There was better agreement between 3D and electromagnetically derived flow rates than there was between the 2D and the reference values (r=.94, y=1.0x-0.16, difference=0.02 L/min for the 3D method; r=.80, y=1.6x-0.3, difference=1.2 L/min for the 2D hemispherical method; r=.75, y=0.90x+0.2, difference=-0.20 L/min for the 2D hemielliptical method). CONCLUSIONS: Without any geometrical assumption, the 3D method provided better delineation of the FC zones and direct measurements of FC surface areas, permitting more accurate quantification of the severity of AR than the 2D methods.

Animals↗
PubMed1997

Stimulation of proliferation in human colon cancer cells by human monoclonal antibodies against the TF antigen (galactose beta1-3 N-acetyl-galactosamine).

In many tissues, the TF (Thomsen-Friedenreich) blood group antigen (Galbeta1-3GalNAc alpha-) behaves as an onco-foetal carbohydrate antigen, showing increased expression in malignancy and hyperplasia. Dietary lectins which bind the TF antigen have marked effects on proliferation of epithelial cells without cytotoxicity. This led us to speculate that anti-TF antibodies, including those that naturally occur in humans, might have similar effects. Five anti-TF antibodies, TF2 (human), TF5 (human), 5A8 (mouse), 8D8 (mouse) and BM22 (mouse), but not TFI (human) or 49H.9 (mouse), showed marked dose-dependent stimulation (95-192%) of [3H]thymidine incorporation by HT29 human colon cancer cells. Similar stimulation of proliferation of HT29 cells by these monoclonal antibodies (MAbs) was found when cell count assessment was used. Antibody-stimulated proliferation was inhibited by co-incubation with glycoproteins expressing Galbeta1-3GalNAc alpha- (asialo glycophorin or [Galbeta1-3GalNAc alpha-O-p-aminophenyl]n-human serum albumin). A proliferative effect of these antibodies was also demonstrated on human colon cancer cell lines LS174T and HT29-MTX but not on Caco-2 cells. Although immunoblotting showed similar binding patterns of all the antibodies on HT29 cell membrane extracts, there was little correlation between cell surface binding assessed by immunofluorescence and proliferative response, and internalization of the biotinylated antibody TF5 was demonstrated by confocal microscopy. Our results provide further evidence that cell surface glycoproteins which express TF antigen may play an important role in the regulation of cell proliferation and also suggest that human anti-TF antibodies may have proliferative effects on cells which express TF antigen.

Antibodies↗
PubMed1997

Vena contracta imaged by Doppler color flow mapping predicts the severity of eccentric mitral regurgitation better than color jet area: a chronic animal study.

OBJECTIVES: This study sought to evaluate the relation between the color Doppler-imaged vena contracta and the severity of mitral regurgitation (MR) in a chronic animal model of MR. BACKGROUND: The vena contracta, which is defined as the smallest connection between the laminar flow acceleration zone and the turbulent regurgitant jet, has been reported to be a clinically useful marker for evaluating the severity of valvular regurgitation. METHODS: Six sheep with chronic MR produced by previous operation severing the chordae tendineae were examined. MR jet flows and vena contracta widths were imaged using a Vingmed 775 scanner with a 5-MHz transducer. Image data were directly transferred in digital format to a microcomputer for off-line measurement. MR was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions determined using mitral and aortic electromagnetic flow probes and flowmeters balanced against each other. RESULTS: Vena contracta width correlated well with regurgitant severity determined by electromagnetic flowmeters (r = 0.95, SEE = 0.05 cm, p < 0.0001 for peak regurgitant flow rate; r = 0.85, SEE = 0.08 cm, p < 0.0001 for regurgitant stroke volume; r = 0.90, SEE = 0.07 cm, p < 0.0001 for regurgitant fraction). CONCLUSIONS: This study shows that the vena contracta width method is useful for predicting the severity of MR. It is simple and conveniently available with high resolution equipment. The quantitative comparisons in the present study lay the foundation for future clinical and research studies using this vena contracta technique.

Animals↗
PubMed1997

Quantifying aortic regurgitation by using the color Doppler-imaged vena contracta: a chronic animal model study.

BACKGROUND: The aim of the present study was to evaluate the accuracy of determining aortic effective regurgitant orifice area (EROA) and aortic regurgitant volume by using the color Doppler-imaged vena contracta (CDVC). METHODS AND RESULTS: Twenty-nine hemodynamically different states were obtained pharmacologically in eight sheep with surgically induced aortic regurgitation. Instantaneous regurgitant flow rates (RFRs) were obtained with aortic and pulmonary electromagnetic flowmeters (EFMs), and aortic EROAs were determined from EFM RFRs divided by continuous wave Doppler velocities. Color Doppler-derived EROAs were estimated by measuring the maximal diameters of the CDVC. Peak and mean RFRs and regurgitant volumes per beat were calculated from vena contracta area continuous wave diastolic Doppler velocity curves. Peak EFM-derived RFRs varied from 1.8 to 13.6 (6.3+/-3.2) L/min (range [mean+/-SD]), mean RFRs varied from 0.7 to 4.9 (2.7+/-1.3) L/min, regurgitant volumes per beat varied from 7.0 to 48.0 (26.9+/-12.2) mL/beat, and the regurgitant fractions varied from 23% to 78% (55+/-16%). EROAs determined by using CDVC measurements correlated well with reference EROAs obtained by using the EFM method (r=.91, SEE=0.07 cm2). Excellent correlations and agreements between peak and mean RFR and regurgitant volumes per beat as determined by Doppler echocardiography and EFM were also demonstrated (r=.95 to .96). CONCLUSIONS: Our study indicates that the CDVC method can be used to quantify both aortic EROAs and regurgitant flow rates.

Animals↗
PubMed1997

A Canadian hospital-based HIV/hepatitis C look-back notification program.

OBJECTIVE: To describe the process used to notify pediatric patients who received transfusions of blood or blood products at our institution before donor blood was routinely screened for antibodies to HIV (1985) and hepatitis C virus (1990), and to evaluate the effectiveness of the notification program. DESIGN: Patients who had received transfusions were identified through the hospital's medical records and the records from the Transfusion Medicine Laboratory. Patients were contacted by registered mail to provide notification of transfusion. A questionnaire was included with the notification to obtain information about the patient's awareness of the transfusion and whether he or she had undergone or planned to undergo testing for HIV and hepatitis C virus. SETTING: Tertiary care university-affiliated teaching hospital in Hamilton, Ont. PATIENTS: Patients 16 years of age or younger who had received blood products between February 1978 and November 1985. Patients who had received only albumin or immune serum globulin were not included as these products were not associated with viral transmission in Canada. RESULTS: Notification letters were sent to 1546 patients. Of these letters 522 (33.8%) were returned undelivered. Of the 1024 patients contacted 493 (48.1%) responded to the questionnaire, of whom 157 (31.8%) were not aware of their transfusion. A total of 130 (26.4%) of the respondents had already undergone testing for HIV, and 342 (69.4%) indicated that they would undergo such testing as a result of the notification. In contrast, only 30 (6.3%) of 474 respondents had undergone testing for hepatitis C virus, but 425 (89.7%) indicated that they would undergo such testing. Overall, the patients' response to the notification was neutral or positive; however, a number of patients expressed dissatisfaction and anxiety. CONCLUSIONS: The high proportion of patients who were unaware that they had undergone transfusion and who decided to undergo testing for HIV and hepatitis C virus as a result of notification supports the use of notification programs such as this one.

Adolescent↗