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Biomedical subjects

R M Griffin

Publications and source records attributed to R M Griffin.

At least 19 recordsLinked to original sources
PubMed1999

A carbon column-based liquid chromatography electrochemical approach to routine 8-hydroxy-2'-deoxyguanosine measurements in urine and other biologic matrices: a one-year evaluation of methods.

8-Hydroxy-2'-deoxyguanosine (8OH2'dG) is a principal stable marker of hydroxyl radical damage to DNA. It has been related to a wide variety of disorders and environmental insults, and has been proposed as a useful systematic marker of oxidative stress. Analytic procedures for 8OH2'dG in DNA digests are well established; however, routine measurement of free 8OH2'dG in other body fluids such as urine or plasma has been problematic. This has hindered its evaluation as a general clinical, therapeutic monitoring, or environmental assessment tool. Therefore, we developed a liquid chromatography electrochemical column-switching system based on the use of the unique purine selectivity of porous carbon columns that allows routine accurate measurement of 8OH2'dG in a variety of biologic matrices. This paper describes the rationale of the system design and the protocols developed for 8OH2'dG in urine, plasma, cerebrospinal fluid, tissue, DNA, saliva, sweat, kidney dialysis fluid, foods, feces, culture matrix, and microdialysates. Concentrations in both human and animal body fluids and tissues are reported. The system performance is discussed in the context of a 1-year evaluation of the methods applied to approximately 3600 samples, using internal quality control and external blind testing to determine long-term accuracy. The methods are reliable and accurate, and therefore should prove useful in assessing the role and utility of oxidative DNA damage in aging and human illness.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1993

Prolonged use of isoflurane in a patient with tetanus.

We describe a patient with tetanus, who received isoflurane for sedation to facilitate controlled mechanical ventilation. Isoflurane was administered for 34 days, resulting in a sustained serum inorganic fluoride ion concentration in excess of 50 mumol litre-1 and a peak serum inorganic fluoride ion concentration of 87 mumol litre-1. Although these concentrations are potentially nephrotoxic, no toxicity was evident clinically.

Adult↗
PubMed1990

Aspiration pneumonia and the laryngeal mask airway.

A case of aspiration pneumonia is reported after the use of a laryngeal mask airway in a young woman undergoing an elective cholecystectomy. The case illustrates the hazards of regurgitation with the laryngeal mask airway and the need for further evaluation when used with controlled mechanical ventilation.

Adult↗
PubMed1989

Cardiovascular effects of a nifedipine infusion during fentanyl-nitrous oxide anesthesia in dogs.

The hemodynamic effects of a nifedipine infusion were investigated in eight dogs given fentanyl/pancuronium/nitrous oxide/oxygen anesthesia. Nifedipine (20 micrograms/kg) was given intravenously over two minutes immediately prior to each 30-minute infusion at 2 micrograms/kg/min, 4 micrograms/kg/min, and 6 micrograms/kg/min. The range of plasma nifedipine levels obtained was 52.1 to 113.7 ng/mL. The predominant hemodynamic effects were significant reductions in systemic vascular resistance (SVR) and mean aortic pressure (MAP), accompanied by a rise in cardiac index and heart rate (HR). Administration of calcium chloride (20 mg/kg) after the nifedipine infusion had no effect on SVR or MAP, but HR was significantly reduced. Serum epinephrine and norepinephrine levels increased after the infusion of nifedipine and suggested that fentanyl did not completely overcome the sympathetic response to the profound vasodilatation. The resulting tachycardia in combination with diastolic hypotension from nifedipine could have a detrimental effect on the myocardial oxygen balance.

Anesthesia, Inhalation↗
PubMed1989

Comparison of methohexital and propofol for electroconvulsive therapy: effects on hemodynamic responses and seizure duration.

Electroconvulsive therapy can produce severe disturbances in the cardiovascular system, most commonly a transient period of hypertension. This study was designed to determine whether propofol, in comparison with methohexital, would attenuate this hypertensive response. Fifteen patients were studied during courses of six ECT administrations, each patient receiving propofol or methohexital on different occasions. Arterial pressure, heart rate, and cardiac rhythm were recorded. The induction doses were 1.08 +/- 0.03 mg.kg-1 of methohexital, and 1.60 +/- 0.04 mg.kg-1 of propofol. Systolic pressure, diastolic pressure, and heart rate were consistently lower following propofol than methohexital (P less than 0.005). The mean maximum increase over baseline systolic pressure was 2.1 +/- 2.9 mmHg with propofol, and 26.7 +/- 4.5 mmHg with methohexital (P less than 0.001). Cardiac rhythm abnormalities were infrequent, and their incidence did not differ significantly between the two induction agents (P greater than 0.3). The duration of seizures, as measured clinically, was reduced with propofol (17.9 +/- 2.5 s) in comparison with methohexital (30.9 +/- 2.8 s) (P less than 0.001). Recovery times were similar for the two agents. Since the role of seizure duration in the therapeutic efficacy of ECT remains controversial, propofol may be a useful induction agent for this procedure.

Analysis of Variance↗
PubMed1989

Hemodynamic effects of verapamil during fentanyl-nitrous oxide anesthesia.

The hemodynamic effects of a verapamil infusion were investigated in six dogs given fentanyl-nitrous oxide anesthesia. Verapamil, 0.2 mg/kg, was given followed by an infusion of 3, 6, and 9 micrograms/kg per minute, which produced plasma verapamil concentrations ranging from 98 to 204 ng/ml. Verapamil significantly reduced the systemic vascular resistance index and mean arterial pressure. The decrease in afterload led to an increase in cardiac index, since there was little change in myocardial contractility (LV dP/dt). Administration of calcium chloride, 20 mg/kg, did not reverse the hemodynamic effects of verapamil. The data indicate that in dogs verapamil can be given, even in high concentrations, during fentanyl-nitrous oxide anesthesia without serious adverse electrophysiologic or hemodynamic consequences.

Anesthesia, Inhalation↗
PubMed1988

Haemodynamic effects of diltiazem during fentanyl-nitrous oxide anaesthesia. An in vivo study in the dog.

The haemodynamic effects of diltiazem were studied in six dogs during fentanyl-nitrous oxide (in oxygen) anaesthesia. A bolus of diltiazem 300 micrograms kg-1 was given, followed by infusions at 30, 60 and 90 micrograms kg-1 min-1 which produced plasma diltiazem concentrations of 392 +/- 30, 908 +/- 54 and 1483 +/- 134 ng ml-1, respectively. Diltiazem significantly reduced systemic vascular resistance index, mean arterial pressure, heart rate and PR interval. The decrease in afterload increased cardiac index, since there was little change in myocardial contractility (LV dP/dt). Five dogs developed second degree atrioventricular (AV) block in association with the highest dose. Administration of calcium chloride 20 mg kg-1 did not reverse the haemodynamic or electrophysiological effects of diltiazem. Isoprenaline increased heart rate and restored sinus rhythm in four dogs with AV block.

Anesthesia, General↗
PubMed1987

Myocardial ischaemia during non-cardiac surgery. A comparison of different lead systems using computerised ST segment analysis.

Computerised ST segment analysis was used to compare the frequency of ischaemia occurring in electrocardiographic leads II, V5, CS5 and CB5. Three out of 15 patients with ischaemic heart disease developed ischaemic changes, which were evident in all four leads in each patient. A single bipolar lead may be substituted for a true V5 lead when monitoring patients at increased risk of developing myocardial ischaemia. ST segment analysis facilitates the early diagnosis of peri-operative myocardial ischaemia, which may otherwise be missed on the standard electrocardiogram.

Aged↗
PubMed1986

Biological monitoring for heavy metals: practical concerns.

Some of the practical concerns associated with performing routine analyses of heavy metals (cadmium, lead, mercury, and arsenic) in various biological matrices are the selection of the biological matrix for monitoring, the sample collection, sample storage and shipment, and sample preparation and analysis. Other factors that affect the quality of the analytical values include contamination of sampling materials, blood drawing procedures, methods of obtaining urine samples, sample homogeneity, instrument calibration and performance, and laboratory quality control programs. A total system quality control approach is necessary to obtain accurate analyses of metals in biological samples, just as it is in all analytical situations.

Arsenic↗
PubMed1985

Electrocardiographical changes in the peri-operative period. A pilot study.

The value of continuous electrocardiogram recording in the peri-operative period has been examined. In a group of 15 patients, 14 developed changes two of which persisted into the postoperative period. Dysrhythmias, ST segment and T-wave changes occurred frequently. Continuous recording is of potential benefit in the study of cardiovascular disease and therapy in the peri-operative period.

Adult↗
PubMed1984

Forum. A comparison between the midline and paramedian approaches to the extradural space.

A prospective, randomised study was devised to compare the midline and paramedian approaches to the extradural space in women during labour. The two approaches were equally successful with respect to catheter insertion and analgesia and had a similar incidence of complications, although the paramedian approach caused patients more discomfort. Since only 2 ml of 1% lignocaine with adrenaline were infiltrated prior to insertion of the Tuohy needle, a greater volume of the local anaesthetic may reduce the discomfort of using the paramedian approach.

Anesthesia, Epidural↗
PubMed1983

Direct determination of lead in evaporated milk and apple juice by anodic stripping voltammetry: collaborative study.

A method for the direct determination of lead in evaporated milk and in fruit juice with no prior sample digestion was successfully collaborated by 13 laboratories. The anodic stripping voltammetric (ASV) method studied consisted of adding 0.2 mL aliquots of evaporated milk or 0.3 mL aliquots of fruit juice to 2.9 mL of a dechelating reagent, Metexchange. The reagent-sample mixture is then analyzed for lead by ASV with no further sample preparation. Each collaborator received 24 samples, 2 each at 5 different levels (0.07-0.70 ppm for spiked evaporated milk and 0.09-0.87 ppm for spiked apple juice) along with duplicate practice samples of labeled lead content at each of 2 levels for each sample type. All unknowns were coded with random numbers. Approximately 69% of the reporting laboratories had never analyzed either evaporated milk or fruit juice for lead. Average time between receipt of samples and reporting of results was 1.6 days for all laboratories. The pooled variations between duplicate determinations for apple juice and evaporated milk were 0.00059 and 0.00043, respectively. The method was adopted official first action for both fruit juice and evaporated milk.

Animals↗
PubMed1980

The response of cage-reared cockerels to dietary medication with growth promoters. I. Size and consistency of the response.

Day-old cockerels were used to examine the growth responses obtained when 50 ppm procaine penicillin, 25 ppm zinc bacitracin, or 20 ppm nitrovin were administered in a wheat-based diet. The birds were fed ad libitum from one day of age a plain or supplemented diet in a series of 10, 21, and 56-day tests conducted between 1971 and 1974. Growth responses, measured by improvement in the live weight gain and feed conversion, were obtained with each treatment, consistently over each annual period. The penicillin and zinc bacitracin gave maximal differences in live weight gain compared with the controls before 14 days of age and, possibly, before 7 days of age, whereas the maximal response to treatment with nitrovin occurred after 14 days of age.

Animals↗