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D J Jones

Publications and source records attributed to D J Jones.

At least 37 records · Page 2Linked to original sources
PubMed1997

Determination of eltanolone in human plasma by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of eltanolone in plasma has been developed. Plasma samples containing eltanolone were diluted with acetonitrile to precipitate plasma proteins, and derivatized with 2,4-dinitrophenylhydrazine before direct injection onto a C18 column. The mobile phase was acetonitrile-water (70:30, v/v) containing 0.1% trifluoroacetic acid and detection was by UV absorbance at 367 nm. The quantitation limit was 0.020 microg/ml. The method has proven to be rapid, precise and sensitive in the range of concentrations found during and following intravenous anaesthesia.

Anesthetics, Intravenous↗
PubMed1997

The aortic homograft: evolution of indications, techniques, and results in 107 patients.

BACKGROUND: Homograft aortic valve replacement has been performed in 107 patients during the past 7 years. Two primary methods of implantation were used (intraaortic and root replacement). Results of both methods are presented. METHODS: Intraaortic implantation (subcoronary or cylinder technique) was performed in 36 patients (mean age, 54 years) for aortic stenosis or regurgitation (31 patients) and endocarditis (5 patients). Aortic root replacement was performed in 71 patients (mean age, 62 years). The majority (58 patients) had complex root pathologies such as ascending aneurysm, dissection, or prosthetic endocarditis with annular destruction. Early results were assessed with intraoperative or predischarge echocardiography; annual echocardiograms provided long-term follow-up. Left ventricular mass was calculated in patients with long-standing pathology for whom preoperative and postoperative data were available. RESULTS: Early valvular insufficiency was documented in 16 of the 36 intraaortic implants (44%); 9 of these have had progression of the insufficiency. Of the 20 patients who had trivial or no early insufficiency, significant insufficiency has developed in 7 and mild insufficiency has developed in 5. Calculation of left ventricular mass revealed a mean reduction of 11% at 1 year. There has been no mortality, endocarditis, or homograft-related reoperation in the intraaortic group with a mean follow-up of 50 months. The root replacement group had a hospital mortality of 17%. The cardiac pathology was limited to the aortic valve in 12 patients; mortality in this subset was zero. There has been no significant early or late postoperative valvular insufficiency in the 59 surviving patients. More rapid left ventricular mass reduction was seen in this group with a 26% mean reduction within 1 year. A mean follow-up of 32 months in the root replacement group has seen no homograft-related reoperations. CONCLUSIONS: Although the lack of early mortality in the intraaortic group makes this technique appealing, the high incidence of early insufficiency with the realistic expectation of progression has led to our abandonment of the intraaortic technique. Homograft aortic root replacement confers a higher mortality based on the severity of aortic pathology, but offers excellent long-term hemodynamics in any patient. We have expanded our indication for homograft root replacement to include patients with isolated valvular disease rather than reserving it for those patients with extensive root pathology.

Adult↗
PubMed1997

Coinfection of wild ducks by influenza A viruses: distribution patterns and biological significance.

Coinfection of wild birds by influenza A viruses is thought to be an important mechanism for the diversification of viral phenotypes by generation of reassortants. However, it is not known whether coinfection is a random event or follows discernible patterns with biological significance. In the present study, conducted with viruses collected throughout 15 years from a wild-duck population in Alberta, Canada, we identified three discrete distributions of coinfections. In about one-third of the events, which involved subtypes of viruses that appear to be maintained in this duck reservoir, coinfection occurred at rates either close to or significantly lower than one would predict from rates of single-virus infection. Apparently, the better adapted an influenza A virus is to an avian population, the greater is its ability to prevent coinfections. Conversely, poorly adapted, nonmaintained viruses were significantly overrepresented as coinfectants. Rarely encountered subtypes appear to represent viruses whose chances of successfully infiltrating avian reservoirs are increased by coinfection. Mallards (Anas platyrhynchos) and pintails (A. acuta) were significantly more likely to be infected by a single influenza A virus than were the other species sampled, but no species was significantly more likely to be coinfected. These observations provide the first evidence of nonrandom coinfection of wild birds by influenza A viruses, suggesting that reassortment of these viruses in a natural population does not occur randomly. These results suggest that even though infections may occur in a species, all subtypes are not maintained by all avian species. They also suggest that specific influenza A virus subtypes are differentially adapted to different avian hosts and that the fact that a particular subtype is isolated from a particular avian species does not mean that the virus is maintained by that species.

Adaptation, Physiological↗
PubMed1997

The influence of meperidine and nitrous oxide on respiratory depression in rats.

Narcotic sedation is commonly accomplished with nitrous oxide (N2O) coadministration. Concerns regarding respiratory morbidity and mortality with drug combinations have been reported in the literature, particularly in patients not receiving supplemental oxygen (O2). The purpose of this investigation was to determine the effect of meperidine alone and in combination with N2O on respiration in laboratory rats by evaluating cardiovascular and arterial blood gas data. Fifty-four Sprague-Dawley rats were assigned to one of six groups (nine per group). Groups were allocated based upon the dosage of meperidine administered (0, 4.0, or 8.0 mg/kg intraperitoneally [i.p.]) and exposure to N2O (50% with oxygen) or O2 (100%). Following meperidine administration, animals were placed into a sealed chamber through which flowed either N2O or O2. Arterial blood was obtained, at baseline and at 15-min intervals, from a femoral artery catheter and pH, O2, CO2 (mm Hg), and oxygen saturation (%) were determined. Plasma samples were analyzed using a System 1306 pH/blood gas analyzer. Group comparisons demonstrated that: (a) N2O coadministration, in animals pretreated with meperidine, did not result in increased arterial CO2 levels, and (b) as expected, arterial O2 levels in all groups increased significantly from preexposure baseline values (P < 0.05). This investigation demonstrated that the coadministration of N2O to meperidine-sedated animals did not enhance respiratory depression.

Analgesics, Opioid↗
PubMed1996

Determination of (R)-(+)- and (S)-(-)-isomers of thiopentone in plasma by chiral high-performance liquid chromatography.

A method for the determination of R-(+)- and (S)-(-)-isomers of thiopentone in plasma was developed. Following liquid-liquid extraction, the separation of enantiomers of thiopentone and the internal standard (racemic ketamine) was achieved by high-performance liquid chromatography on an alpha1-acid glycoprotein (AGP) column with ultraviolet detection at 280 nm. The mobile phase consisted of 20 mM KH2PO4 buffer-2-propanol-methanol (93.5:5.0:1.5) at pH 5.0. The flow-rate was 0.9 ml/min. The limit of quantification for each isomer was approximately 10 ng/ml. The assay is suitable for pharmacokinetic studies of (R)-(+)- and (S)-(-)-isomers of thiopentone, following usual bolus intravenous clinical doses of the racemic drug.

Aged↗
PubMed1996

Comparison of characteristics of patients and treatment outcome for pulmonary non-tuberculous mycobacterial infection and pulmonary tuberculosis.

BACKGROUND: Patients with non-tuberculous mycobacteria are usually started on conventional antituberculous triple therapy once acid fast bacilli are detected, before the exact type of mycobacteria has been identified. The ability to identify the characteristics of patients with tuberculous and non-tuberculous mycobacteria may be helpful in identifying before treatment those patients more likely to have non-tuberculous infection. METHODS: A retrospective study was conducted of all patients in one unit in whom non-tuberculous mycobacteria were identified in sputum or bronchoalveolar washings in the period 1987-93. The pattern of drug resistance was determined from laboratory records, and all case notes and chest radiographs were reviewed to identify the underlying disease and treatment outcome. All cases were compared with a matched control group of patients with culture positive Mycobacterium tuberculosis diagnosed during the same period. RESULTS: In the period studied there were 70 non-tuberculous and 221 tuberculous isolates. The non-tuberculous bacteria were typed as follows: M xenopi 23 (33%), M kansasii 19 (27%), M fortuitum 14 (20%), others 14 (20%). Of those with non-tuberculous mycobacteria, 83% were white subjects compared with 47% for tuberculosis. Patients with non-tuberculous mycobacteria were older than those with tuberculosis. Pre-existing lung disease or AIDS was present in 81% of patients with non-tuberculous mycobacteria and in 17% of patients with tuberculosis. Sensitivity to rifampicin and ethambutol was seen in 95% of M xenopi and 96% of M kansasii isolates. Relapse occurred in 60% of cases infected with M xenopi, 20% infected with M kansasii, and in 7% of cases with tuberculosis. CONCLUSIONS: In the population studied non-tuberculous mycobacteria occurred most frequently in elderly white subjects with pre-existing lung disease. If mycobacteria are detected in this group, consideration should be given to the possibility of non-tuberculous infection before embarking on treatment. A combination containing rifampicin and ethambutol is effective. The relapse rate for infection with M xenopi is high and prospective studies of the effect of the above combination of antituberculosis drugs are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Effect of ractopamine on growth performance, carcass composition, and cutting yields of pigs slaughtered at 107 and 125 kilograms.

At approximately 68 kg live weight, crossbred barrows and gilts (n = 144) were allocated to be fed to one of two weight end points (107 kg and 125 kg). Pigs from each weight group were treated with Ractopamine (RAC) (0, 10, or 20 ppm; n = 24/ treatment for the last 40 kg of gain. Feed consumption and weight gain were measured. Pigs were slaughtered and carcass measurements made at 24 h postmortem. Carcasses were fabricated into wholesale, trimmed wholesale, and boneless wholesale cuts for cutting yields. Hams were separated into muscle, fat, and bone. The RAC improved growth characteristics and carcass characteristics. Pigs fed RAC had increased (P < .01) average daily gain and improved (P < .01) feed:gain ratio over controls in each weight group. Carcasses from pigs treated with RAC had larger (P < .01) longissimus muscle area and reduced (P < .01) fat at the 10th rib. Cuts from 125-kg pigs were generally heavier than those from 107-kg pigs. The RAC increased (P < .05) the boneless cut weights of both weight groups. Percentage of dissected lean from the hams of RAC-treated pigs was (P < .05) higher than that of controls. Few consistent differences were observed between the 10 and 20 ppm of RAC treatments. Results from this study indicate that RAC had positive effects on the growth characteristics, carcass characteristics, and carcass cutting yields of pigs representative of the broad spectrum of market weights.

Adrenergic beta-Agonists↗
PubMed1996

Requiem or renaissance for the law reform commission of Canada?

From 1975 to 1992, the protection of life project of the Law Reform Commission of Canada sought to help society answer some of the legal and bioethical riddles posed by the biomedical revolution, particularly as these developments affected the protection of human life, public safety and fundamental values. A focus on the risks, benefits, rights and duties associated with biomedical sciences and technology provided the project both a means of inquiry into pressing health law and bioethics questions, and a methodology of law reform. The inquiry was often applied through a transdisciplinary perspective, to such topics as the redefinition of death, medically assisted procreation, behavioral alteration, human experimentation, organ transplantation, consent, and the criminal law. Amid recent initiatives to resurrect the Commission, the contributions of the protection of life project are likely to be judged by the bioethico-legal decision-making, dispute resolution, legislative or regulatory enactments and court decisions influenced by its corpus of thought.

Advisory Committees↗
PubMed1995

Normal postoperative gastric emptying after orthopaedic surgery with spinal anaesthesia and i.m. ketorolac as the first postoperative analgesic.

We have assessed the effect of i.m. ketorolac or morphine on early postoperative gastric emptying of liquids in patients undergoing orthopaedic surgery with spinal anaesthesia. Liquid gastric emptying was measured by absorption of paracetamol with patients acting as their own controls. There was no delay after ketorolac 30 mg, but morphine 10 mg resulted in marked delay. There was no difference in postoperative visual analogue pain scores between treatments.

Acetaminophen↗
PubMed1995

A biomechanical comparison of two methods of fixation of fractures of the forearm.

In this study two different types of forearm internal fracture fixations were compared: limited-contact dynamic compression (DC) plates and fluted intramedullary (IM) rods. Eight matched pairs of intact forearms, consisting of the distal part of the humerus, elbow joint, radius, ulna, interosseus membrane, wrist joint, and metacarpals, were randomly separated into two groups. Each was placed into a custom-designed apparatus and subjected to medial bending, supination, pronation, axial compression, and distraction loading. Loads were applied by a materials testing system, and angular displacements were measured by inclinometers. The procedure consisted of first testing specimens intact, then retesting after osteotomizing and fixing the radius with either a plate or rod in half of the group and retesting after osteotomizing and fixing the ulna in the other half. Testing was continued by osteotomizing and remaining intact bone to create a two-bone fracture, fixing them, and retesting after creating a 5-mm gap at the osteotomy sites. These tests showed that the intact ulna contributes more to forearm stability in bending and torsion than does the radius. Therefore, if the radius is fractured but the ulna remains intact, IM rodding will produce constructs with greater stiffnesses, particularly in torsion, than if the ulna is fractured and the radius is intact. In the case of a two-bone fracture, implantation of rods will result in a construct with significantly less stiffness in torsion, as well as distraction and compression (in the case of a fracture gap), than if the fractures were plated.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1995

The efficacy of adding a continuous intravenous morphine infusion to patient-controlled analgesia (PCA) in abdominal surgery.

The effect of adding a continuous infusion of morphine 1 mg/hr to patient-controlled intravenous analgesia was studied in a randomized double-blind trial. Ninety-six patients scheduled for abdominal surgery were enrolled; 38 received PCA and continuous infusion (PCA + C), 45 received PCA alone and 13 were excluded because of protocol violations. PCA was delivered via an ABBOTT 4200 pump with settings of morphine 1 mg bolus and five-minute lockout in both groups. A separate pump delivered a continuous infusion of morphine 1 mg/ml (PCA + C) or 9% normal saline (PCA) at 1 ml/hr for three postoperative days. Pain was assessed by hourly verbal pain scores (VPS) and daily visual analog pain scores at rest and on movement (VAS(rest), VAS(move)). PCA delivered morphine and the demand to delivery ratio (D/D ratio) were used as indirect indicators of pain. These were assessed during daytime (0800-2200 hours), sleep (2200-0500 hours) and on first waking (0500-0800 hours). Patient demographics were similar. Patients receiving a continuous infusion had lower pain scores during the first 24 hours but not thereafter (VPS P = 0.04, VAS(move) P = 0.02). The PCA group delivered more PCA morphine during 0500-0800 hours and 0800-2200 hours on the first day only. There was no significant difference in the D/D ratio for any time period during the three days. Total morphine delivery was greater in the PCA + C group on the second and third postoperative days (P = 0.009 and P = 0.0001 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1995

Ambulatory oxygen therapy in stable kyphoscoliosis.

Patients with chronic obstructive pulmonary disease (COPD) may benefit from ambulatory oxygen; however, the effect of exercise on arterial oxygen saturation (Sa,O2) in patients with kyphoscoliosis and of correction with ambulatory oxygen have not been previously reported. Twelve patients with stable kyphoscoliosis (mean (SD) Cobb angle 79 (26) degrees) were studied, with mean (SD) arterial oxygen tension (Pa,O2) 8.96 (0.93) kPa, arterial carbon dioxide tension (Pa,CO2) 6.52 (0.66), forced expiratory volume in one second (FEV1) 0.90 (0.15) L, forced vital capacity (FVC) 1.34 (0.46) L. Six-minute walking tests with oximetry and visual analogue scores (VAS) for breathlessness were performed on air (baseline), and with cylinders containing air and oxygen at 2 L-min-1. Cylinder walks were in random order, with patients blinded to cylinder content. Patients showed oxygen desaturation at each stage of the study. At baseline, oxygen desaturation during exercise was correlated with deterioration in VAS breathlessness scores. Ambulatory oxygen produced significant improvements in desaturation, breathlessness scores and recovery time compared to baseline and air cylinder walks. There was no relationship between baseline desaturation and changes in walking distance. Although exercise desaturation, breathlessness and recovery times were significantly improved with ambulatory oxygen at 2 L.min-1, walking distance was unaffected. We conclude that patients with moderate to severe kyphoscoliosis have significant oxygen desaturation on exercise and should thus routinely receive oximetry on exercise and assessment for ambulatory oxygen therapy.

Dyspnea↗