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Biomedical subjects

P L Ross

Publications and source records attributed to P L Ross.

At least 19 recordsLinked to original sources
PubMed1999

Racial differences between solid organ transplant donors and recipients in British Columbia: a five-year retrospective analysis.

BACKGROUND: We attempted to determine whether significant racial differences exist between organ donors and transplant recipients in British Columbia, and whether differences exist between individual organ transplant programs (lung, heart, kidney, liver, and pancreas). The design of the study was a retrospective review. METHODS: We used the database of the British Columbia Transplant Society, a provincial agency, for the years 1992 to 1997 inclusive. The outcome measures were a comparison of racial characteristics of organ donors and transplant recipients collectively and by individual organ transplant program. RESULTS: There were 236 organ donors and 766 transplant recipients. Comparing racial groups between donors and recipients, Caucasians contributed the most donors (93.2%) but received proportionately fewer organs (73.4%, P<0.000001). Orientals donated 3.4% of all organs but constituted 14.4% of all recipients (P<0.00001). Non-Oriental, non-Caucasians (predominantly Asian Indians and Native Aboriginals) constituted 3.4% of all donors and 12.2% of all recipients (P=0.0001). Among the individual organ transplant programs, lung, heart, and pancreas recipients were predominantly Caucasian (148 of 156 recipients). Oriental recipients were more likely to be kidney recipients (19.8% of all kidney recipients) compared with all Oriental recipients (P<0.000001). Likewise, Asian Indians were more likely to be kidney recipients (7.2% of all kidney recipients) compared with all Asian Indian recipients (P<0.0001). Native Aboriginals, however, were more likely to be liver allograft recipients (8.3% of all liver transplants) than nonliver allograft recipients (P=0.017). CONCLUSIONS: In British Columbia, disparity exists between Oriental and non-Oriental, non-Caucasian donors and recipients. Orientals and Asian Indians were more likely to be kidney graft recipients than nonkidney graft recipients, whereas Native Aboriginal recipients seemed more likely to have undergone liver transplantation.

Asian People↗
PubMed1998

Analysis of DNA fragments from conventional and microfabricated PCR devices using delayed extraction MALDI-TOF mass spectrometry.

Applications of polymerase chain reaction (PCR) product analysis using rapid affinity capture followed by delayed extraction (DE) MALDI-TOFMS is presented. Such applications include multiplex short tandem repeat (STR) typing, which is demonstrated for STR systems from conventional and microchip-based thermal cycling instruments. Using the combination of the microfabricated PCR instrument and DE-MALDI-TOFMS, a complete genotyping assay can be performed in under 50 min with a resultant molecular weight accuracy approaching or exceeding 100 ppm through external calibration. The observed resolution and mass accuracy for a 69-base PCR product enables identification of single base substitutions by direct molecular weight determination.

Calibration↗
PubMed1998

Anaesthesia in a parturient with Noonan's syndrome.

PURPOSE: To report the management of labour analgesia and subsequent anaesthesia for postpartum bleeding in a 19-yr-old parturient with Noonan's syndrome. CLINICAL FEATURES: The patient presented in active labour at 36-wk gestation. She was known to have Noonan's syndrome and had been assessed regularly throughout pregnancy. Features of the syndrome exhibited by the patient included typical facies, chest skeletal abnormalities, pulmonary valve dysplasia, mental retardation and lymphoedema. In addition, she had Factor XI deficiency (0.46 mg.L-1) and thrombocytopenia (92 x 10(9).L-1), previously unreported in a parturient with this syndrome. Although epidural analgesia may have been considered the labour analgesic technique of choice, the risk of epidural haematoma caused by her bleeding diathesis made this unacceptable. This risk was balanced against the possibility of a potentially difficult intubation due to facial abnormalities, should emergency operative delivery become necessary. Labour analgesia was provided with intravenous patient controlled opioid analgesia (fentanyl 25 micrograms bolus, five minute lockout) despite her mental retardation. Dilatation and curettage required general anaesthesia after intubation with awake direct laryngoscopy using cautious sedation. CONCLUSION: Noonan's syndrome is characterised by multi-system involvement, requiring thorough preoperative assessment of cardiovascular, skeletal, haematological and central nervous systems. Clotting and platelet defects considerably restrict the possible analgesic and anaesthetic options for labouring patients with this syndrome.

Adult↗
PubMed1998

Early exercise after experimental myocardial infarction: effect on left ventricular remodeling.

BACKGROUND: The effect of exercise on left ventricular remodeling after myocardial infarction is unclear. The purpose of this investigation was to test whether exercise undertaken during the healing phase of an acute myocardial infarction has an adverse effect on left ventricular remodeling. METHODS: Before surgery, rats (n = 94) were allocated randomly to one of four groups: 1) infarct, swimming exercise; 2) infarct, no exercise; 3) sham operation, swimming exercise; 4) sham operation, no exercise. Beginning 1 week after infarction or sham operation, the rats in the exercise groups swam twice daily for 2 weeks. After a deconditioning period of 5 days, the rats were re-anesthetized, hemodynamic measurements were made, and the hearts were fixed for morphometric analysis. RESULTS: Swimming exercise had no effect on remodeling of infarcted myocardium. Rats with infarcts in the swimming and no exercise groups had similar infarct thicknesses (1.1 +/- 0.2 mm and 0.8 +/- 0.2 mm respectively; NS), and similar degrees of infarct expansion (expansion index 1.2 +/- 0.3 and 1.4 +/- 0.3 respectively; NS). Swimming exercise also had no effect on remodeling of non-infarcted myocardium. Left ventricular volumes and pressure-volume relationships were similar in exercised and non-exercised infarcted rats. CONCLUSION: In rats, 2 weeks of swimming exercise, started 1 week after acute experimental myocardial infarction and followed by 5 days of deconditioning, does not have an adverse effect on left ventricular remodeling.

Analysis of Variance↗
PubMed1998

Transjugular intrahepatic portosystemic shunt patency and the importance of stenosis location in the development of recurrent symptoms.

PURPOSE: To analyze in detail the location and types of stenosis and occlusion that occur after transjugular intrahepatic portosystemic shunt (TIPS) creation and to determine the relative contribution of these various types of TIPS malfunction to recurrent symptoms of variceal bleeding or ascites. MATERIALS AND METHODS: In 116 of 217 patients who underwent TIPS creation between June 1990 and July 1995, follow-up portal venography was performed at 6-month intervals and for symptoms of recurrent variceal bleeding or ascites. RESULTS: Cumulative primary venographic patency by means of Kaplan-Meier survival analysis was 55% at 6 months and 5% at 2 years. Secondary patency was 92% at 2 years. Stenosis or occlusion occurred in 63 of 116 patients (54%). In 20 patients (17%), acute shunt occlusions developed less than 30 days after TIPS creation; in 24 patients (21%), tract abnormalities were detected after 30 days; and in 19 patients (16%), hepatic vein stenoses were detected after 30 days. Abnormalities of the parenchymal tract were more often correlated with recurrent variceal bleeding or ascites than were hepatic vein stenoses (odds ratio, 3.6; P = .02). Ten of 14 patients (71%) with detected biliary fistulas to their TIPS had symptoms, and all patients with biliary fistulas had tract abnormalities. CONCLUSION: Tract stenoses and occlusions were the major cause of symptomatic shunt failure after TIPS creation. Substantial bile duct transections are often associated with tract abnormalities and recurrent symptoms. Although common, hepatic vein stenoses were rarely associated with recurrent symptoms in our patient population.

Adult↗
PubMed1997

Discrimination of single-nucleotide polymorphisms in human DNA using peptide nucleic acid probes detected by MALDI-TOF mass spectrometry.

Human genomic and mitochondrial DNA contain large numbers of single-nucleotide polymorphisms (SNPs), many of which are linked to known diseases. Rapid and accurate genetic screening for important SNPs requires a general methodology which is easily implemented. We present here an approach to SNP discrimination based on high-specificity hybridization of peptide nucleic acid (PNA) probes to PCR-amplified DNA. The assay is directly applied to polymorphisms located within hypervariable region 1 of the human mitochondrial genome and type 1 suballeles of the human leukocyte antigen DQ alpha gene. Captured, single-stranded DNA molecules prepared by PCR amplification are hybridized with PNA probes in an allele-specific fashion. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is then used for rapid, precise, and unambiguous detection and identification of the hybridized PNA probes. Since PNA oligomers bind strongly to complementary DNA under minimal salt conditions, the use of PNA probes is compatible with MALDI-TOFMS. The unparalleled ability of MALDI-TOFMS analysis in terms of molecular weight resolution and accuracy, in conjunction with the highly specific PNA hybridization afforded by this method, offers promise for development into a multiplexed, high-throughput screening technique.

DNA↗
PubMed1997

Analysis of short tandem repeat polymorphisms in human DNA by matrix-assisted laser desorption/ionization mass spectrometry.

The analysis of an important class of human genetic polymorphisms, short tandem repeats (STRs), using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is described. Several model STR systems have been investigated to evaluate MALDI-TOFMS as a realistic alternative to established electrophoresis procedures, and to develop rapid and generally applicable approaches to polymerase chain reaction (PCR) product purification for MALDI-TOFMS analysis. A purification/preconcentration method for PCR product preparation based on affinity capture of biotin-labeled PCR products is demonstrated to be directly compatible with MALDI-TOFMS analysis. The entire sample preparation for MALDI-TOFMS analysis immediately following PCR amplification from human DNA extracts can be accomplished routinely in under 12 min in a single Eppendorf tube. The simplicity of this approach essentially eliminates the sample preparation bottleneck encountered with MALDI-TOFMS analysis of PCR products using existing methods. Using this method, encouraging genotyping results are demonstrated for the THO1 and TPOxx STR systems using subpicomole quantities that represent a fraction of the original dsDNA from a single PCR reaction. The technique is also demonstrated to facilitate rapid sizing of PCR fragments larger than 200 bases using MALDI-TOFMS. As described here, the analysis of DNA can be accomplished in a manner that takes advantage of the rapid and accurate analysis capabilities offered by MALDI-TOFMS.

DNA↗
PubMed1996

Detection of pathogenic and non-pathogenic bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The proteins isolated from the whole cells of bacterial pathogens and related non-pathogenic simulants were analyzed directly, with minimal sample preparation by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Inspection of mass spectrometric profiles obtained from direct MALDI-MS analysis of the protein extracts revealed specific biomarkers for individual bacterial cells. The observed biomarkers enabled us not only to detect pathogenic bacteria (Bacillus anthracis, Yersinia pestis and Brucella meliteusis), but also to distinguish them from the corresponding non-pathogenic species. By examining a series of strains of several Bacillus species (anthracis, thuringiensis, cereus and subtilis), it was possible to derive genus, species and strain-specific biomarkers from the measured molecular masses of the intact proteins. Additional series of biomarkers were obtained from direct mass spectrometric analysis of tryptic digests of the protein extracts. The application of this technique for rapid chemotaxonomic classification of microorganisms is demonstrated.

Bacteria↗
PubMed1996

Rapid identification of bacteria by direct matrix-assisted laser desorption/ionization mass spectrometric analysis of whole cells.

Several characteristic ions were observed during the direct analysis of a variety of both gram-negative and gram-positive intact bacterial cells by the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) technique. The entire process, involving absolutely no sample processing, could be completed in less than ten minutes. A number of specific biomarkers, generated reproducibly for each type of cell from the corresponding mass spectrum, permitted the identification, as well as the distinction, of pathogenic bacteria from their non-pathogenic counterparts. In addition, individual strains of a specific organism could also be differentiated easily. Some of these biomarkers correspond to those observed earlier during the MALDI-MS analysis of protein extracts of the same bacteria. This approach, which can yield valuable data for rapid classification and detection of microorganisms, represents a substantial breakthrough for rapid screening of environmental as well as biological samples.

Bacteria↗
PubMed1996

The effect of dilute vasopressin solution on blood loss during operative hysteroscopy: a randomized controlled trial.

OBJECTIVE: To assess the effect of intracervical injection of dilute (0.05 U/mL) vasopressin solution on blood loss during operative hysteroscopy. METHODS: In a randomized, double-blind study, dilute vasopressin solution or placebo (normal saline) was injected into the cervical stroma of 106 women before dilation of the cervix in preparation for operative hysteroscopy. Intraoperative bleeding was calculated by dividing the number of red blood cells per milliliter of outflow distention fluid by the number of red blood cells per milliliter of the woman's blood immediately before the procedure and multiplying this quotient by the total amount of outflow fluid collected. Pressures were kept constant with a hysteroscopic infusion pump. RESULTS: The mean (+/-standard error of the mean) intraoperative blood loss of the treated (vasopressin) and control (placebo) groups was 20.3 +/- 4.1 mL (range 0-135) and 33.4 +/- 5.4 mL (range 0-290), respectively. The volume of distention fluid intravasation in the treated and control groups was 448.5 +/- 47.0 mL (range 30-1410) and 819.1 +/- 79.7 mL (range 20-1977), respectively. The operating time in the treated and control groups was 31.1 +/- 1.2 minutes (range 18-52) and 34.1 +/- 1.3 minutes (range 19-65), respectively. For all three outcome measures, the differences between the two groups were statistically significant, but for visual clarity of the uterine cavity during surgery, the difference was not significant. CONCLUSION: Administration of dilute vasopressin solution (0.05 U/mL) to the cervical stroma significantly reduces blood loss, distention fluid intravasation, and operative time during hysteroscopy. Further evaluation is required to determine the optimum dosage.

Adult↗
PubMed1994

Calcium supplementation with and without hormone replacement therapy to prevent postmenopausal bone loss.

OBJECTIVE: To determine whether augmentation of dietary calcium is effective in the prevention of early postmenopausal bone loss. DESIGN: Three-arm, placebo-controlled, randomized parallel trial. The study duration was 2.9 +/- 1.1 (SD) years. SETTING: General community. PARTICIPANTS: 118 healthy, white women 3 to 6 years after spontaneous menopause, recruited by community announcement. INTERVENTIONS: Random allocation to daily intake of 1700 mg of calcium (calcium carbonate given in divided doses with meals); placebo; or conjugated equine estrogens (0.625 mg; days 1 to 25), progesterone (10 mg; days 16 to 25), and 1700 mg of elemental calcium daily. Each participant received 400 IU of vitamin D daily. MAIN OUTCOME MEASURES: Total body calcium measured by delayed gamma neutron activation analysis and whole-body counting; bone mineral density of the spine, femur, and radius measured by photon absorptiometry. RESULTS: Bone mineral density declined in the placebo group for the lumbar spine (-2.1%/y; 95% Cl, -3.3 to -0.9), femoral neck (-2.0%/y; Cl, -2.6 to -1.2), trochanter (-1.6%/y; Cl, -2.4 to -0.8), Ward triangle (-2.7%/y; Cl, -3.7 to -1.7), and total body calcium (-2.0%/y; Cl, -2.2 to -1.8). Rates of change were intermediate for calcium augmentation compared with placebo and estrogen-progesterone-calcium but statistically significant compared with placebo for total body calcium (-0.5%/y; Cl, -0.9 to -0.1; P = 0.006) and the femoral neck (-0.8%/y; Cl, -1.4 to -0.2; P = 0.03). CONCLUSIONS: Although less effective than estrogen-progesterone-calcium, calcium augmentation alone significantly retards bone loss from the femoral neck and improves calcium balance in recently postmenopausal women. Dietary calcium augmentation should be recommended as a strategic option in helping to prevent early postmenopausal bone loss.

Analysis of Variance↗
PubMed1994

Transcatheter tubal sterilization in rabbits. Technique and results.

RATIONALE AND OBJECTIVES: A potential method of nonsurgical tubal sterilization was tested in rabbits. METHODS: Metal coils were designed which could be placed into the uterotubal junction using transvaginal fluoroscopic fallopian tube catheterization. These metal coils were successfully placed unilaterally in the uterotubal junction of 32 rabbits. The contralateral fallopian tube and uterus were used as a control. The rabbits were bred, and the presence of pregnancies was confirmed by palpation. RESULTS: In 21 rabbits (66%), the coil stayed in place. Sixteen rabbits had multiple gestations on the side without the coil and no gestations on the side with the coil. Three rabbits had gestations on both sides, even though the coil was in place, and two rabbits never conceived. In 11 rabbits (34%) the coil was dislodged as early as 5 days and as late as 18 weeks after the procedure. Five of these 11 rabbits had bilateral embryos, 4 had embryos only on the side contralateral to where the coil had been, and 2 never conceived. CONCLUSIONS: The metal coil does prevent conception if it stays in place at the uterotubal junction. However, the coil failed to prevent pregnancy in 3 of 19 rabbits, and was dislodged in 11 rabbits, giving an overall failure rate for contraception of 44%.

Animals↗
PubMed1993

Patient-controlled epidural analgesia in labour: varying bolus dose and lockout interval.

This double-blind prospective study was designed to determine the best dose variables for patient-controlled epidural analgesia (PCEA) and to compare bolus-only PCEA with continuous infusion epidural analgesia (CIEA) during the first stage of labour. Five groups of parturients self-administered 0.125% bupivacaine with 1:400,000 epinephrine and fentanyl 2.5 micrograms.ml-1 using PCA pumps programmed as follows: Group A, 2 ml bolus/10 min lockout interval (LI); Group B, 3 ml bolus/15 min LI; Group C, 4 ml bolus/20 min LI; Group D, 6 ml bolus/30 min LI; Group E, 8 ml.hr-1 continuous infusion. Hourly assessments included: VAS scores for pain and satisfaction, sensory and motor block, bupivacaine and fentanyl consumption. Blood samples were collected at birth for maternal and fetal fentanyl concentrations. Data from 68 patients showed no differences among groups in pain relief or maternal satisfaction. Most patients received excellent analgesia and those requiring extra epidural supplements were evenly distributed across groups. There was higher consumption of bupivacaine and fentanyl in Group E than in any of the other four groups: bupivacaine mg.hr-1, mean (SD), 9.4 (2.7) in Group E vs 5.2 (1.7) in Groups A-D inclusive (P < 0.0001); fentanyl microgram.hr-1, 19.6 (4.6) in group E vs 12.6 (7.5) in Groups A-D inclusive (P < 0.05). Motor block was minimal, whereas sensory levels were higher at the 3- and 4-hour assessments in Groups D and E than in all other groups (P < 0.05). Plasma fentanyl concentrations were < 0.5 ng.ml-1 in all samples and no sequelae from fentanyl were observed, apart from mild pruritus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Gadolinium-DTPA transplacental transfer and distribution in fetal tissue in rabbits.

RATIONALE AND OBJECTIVES: The authors assessed to what extent the commonly used the magnetic resonance imaging contrast agent, gadopentetate dimeglumine, crosses the placenta. METHODS: Eight pregnant rabbits in the third trimester were injected with 0.1 mmol/kg of gadopentetate dimeglumine, and killed 5, 15, 30, or 60 minutes after injection. Placental and fetal tissues were analyzed for gadolinium content. RESULTS: Placental concentrations of gadolinium were initially high (16.6 +/- 3.4 micrograms/gram) and then declined with a biexponential pattern. Initial gadolinium levels in the fetal organs were low and remained so except for the fetal kidneys, which showed increased levels of gadolinium from 4.3 +/- 1.1 micrograms/gram at 5 minutes to 6.8 +/- 1.8 micrograms/gram at 60 minutes. CONCLUSIONS: The results indicate that gadolinium does cross the rabbit placenta, and that concentrations in the placenta and the fetal urinary tract are sufficient for imaging as well as possible fetal toxicity.

Animals↗
PubMed1990

Comparison of lidocaine CO2, two per cent lidocaine hydrochloride and pH adjusted lidocaine hydrochloride for caesarean section anesthesia.

Lidocaine can be prepared in a variety of ways which may affect the characteristics of neural blockade achieved. Experimental evidence is equivocal as to the clinical impact of the use of different lidocaine preparations. A randomized, double-blind study was performed to investigate the differences in epidural anaesthesia for Caesarean section using three different lidocaine solutions: lidocaine CO2, two per cent lidocaine and two per cent lidocaine with its pH adjusted by the addition of bicarbonate. No differences were found among the groups in time of onset of neural blockade, quality or duration of neural blockade, time to delivery of the infant or volume of anaesthetic solution injected into the epidural space. A significant difference was found between the pH's of the solutions used. It is concluded that all three solutions are equally efficacious in epidural anaesthesia for Caesarean section.

Adult↗
PubMed1990

Epidural sufentanil for post-caesarean section analgesia: lack of benefit of epinephrine.

Epidural sufentanil was administered to 57 women after Caesarean section, under epidural anaesthesia, to provide postoperative analgesia. Each patient received a 30 micrograms dose at the first complaint of pain and this dose was repeated when pain recurred. Epinephrine (1:200,000) was added to the local anaesthetic, sufentanil, both, or neither. The time of onset of analgesia, efficacy, duration of analgesia and the incidence of side-effects were recorded. This dose of epidural sufentanil provided satisfactory postoperative analgesia and no serious side-effects were observed. The onset of analgesia was rapid (4-6 min), but the duration of action was brief (4-5 hr). The addition of 1:200,000 epinephrine had no statistically significant influence on any of the measured variables. Pruritus occurred commonly but never required treatment. Drowsiness was experienced frequently and was felt by some patients to inhibit their interaction with their neonates. Respiratory depression, as defined by a respiratory rate less than 10 bpm, was not observed. A number of patients noted a transient period of euphoria 5-8 min after administration of the epidural sufentanil. The authors feel that epidural sufentanil provides satisfactory analgesia after Caesarean section, but the brief duration of action and the high incidence of drowsiness limit its acceptability for routine use in obstetric patients.

Adult↗
PubMed1989

Cardiovascular collapse following an overdose of prostaglandin F2 alpha: a case report.

A case report is presented of a parturient who suffered severe hypotension and pulmonary oedema following an overdose of intramyometrial prostaglandin F2 alpha. Oxytocin induction of labour in this patient led to a rapid delivery, followed by a hypotonic uterus and postpartum haemorrhage. After resuscitation with blood and crystalloid fluids, the uterus was explored under general anaesthesia. The uterus was free of retained products but the lower uterine segment failed to contract despite bimanual uterine compression and intravenous oxytocin. Prostaglandin F2 alpha was injected into the lower uterine segment via a transvaginal approach. This was rapidly followed by cardiovascular collapse and later by pulmonary oedema. The differential diagnosis and subsequent management are discussed.

Adult↗