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Biomedical subjects

P Butler

Publications and source records attributed to P Butler.

At least 55 records · Page 3Linked to original sources
PubMed1997

Heart rates and abdominal temperatures of free-ranging South Georgian shags, Phalacrocorax georgianus

The South Georgian shag (Phalacrocorax georgianus) shows a remarkable diving ability comparable to that of penguins, yet nothing is known of the physiology of these birds. In this study, heart rates and abdominal temperatures were recorded continuously in four free-ranging South Georgian shags using an implanted data-logger. A time­depth recorder was also attached to the back of the implanted birds to record their diving behaviour. The diving behaviour of the birds was essentially similar to that reported in other studies, with maximum dive durations for individual birds ranging between 140 and 287 s, and maximum depths between 35 and 101 m. The birds, while at the nest, had a heart rate of 104.0±13.1 beats min-1 (mean ± s.e.m.) and an abdominal temperature of 39.1±0.2 °C. During flights of 221±29 s, heart rate and abdominal temperature rose to 309.5±18.0 beats min-1 and 40.1±0.3 °C, respectively. The mean heart rate during diving, at 103.7±13.7 beats min-1, was not significantly different from the resting values, but the minimum heart rate during a dive was significantly lower at 64.8±5.8 beats min-1. The minimum heart rate during a dive was negatively correlated with both dive duration and dive depth. Abdominal temperature fell progressively during a diving bout, with a mean temperature at the end of a bout of 35.1±1.7 °C. The minimum heart rate during diving is at a sub-resting level, which suggests that the South Georgian shag responds to submersion with the 'classic' dive response of bradycardia and the associated peripheral vasoconstriction and utilisation of anaerobic metabolism. However, the reduction in abdominal temperature may reflect a reduction in the overall metabolic rate of the animal such that the bird can remain aerobic while submerged.

Journal Article↗
PubMed1997

Adolescent mothers' self-esteem and role identity and their relationship to parenting skills knowledge.

The purpose of this study was to investigate the relationship between the adolescent mother's self-esteem and her knowledge of parenting skills. Erikson's psychosocial theory provided the basis for the general hypothesis that the adolescent mother's global self-esteem will correlate with her parenting skills knowledge. The findings reported here support the conclusion that self-esteem is a good indicator of the adolescent mother's parenting. There were significant correlations between the mother's baseline self-esteem and her knowledge about role reversal, empathy, developmental expectations, and corporal punishment. The data also supported the hypothesis that adolescent self-esteem is developmentally continuous. Using Erikson's theory, it was argued that the adolescent mother's parenting is at risk if she has not had the opportunity to achieve her role identity, which is a prerequisite for the parenting stage of generativity.

Adolescent↗
PubMed1996

Environmental acidity and white muscle recruitment during swimming in the brown trout (Salmo trutta)

Electromyographic recordings show that, for adult brown trout swum up to their critical swimming speed (Ucrit) in a flume at neutral pH, white muscle recruitment occurred when speeds approached 1 body length s-1 (BL s-1) and continued to Ucrit (approximately 2 BL s-1) at both winter (5 °C) and summer (15 °C) acclimation temperatures. However, in the majority of fish swum up to Ucrit at sublethal acidic pH, continuous white muscle recruitment did not occur, although all swam above 1 BL s-1. Any observed electrical activity of the white muscle in these individuals was, at best, intermittent. Consequently, the mean Ucrit of these fish was approximately half that of fish swum at neutral pH. In all fish at sublethal pH, red muscle activity was observed for the whole duration of the exercise period, showing that swimming speeds greater than 1 BL s-1 were achieved largely aerobically. Fish that were chased around a tank at sublethal pH appeared lethargic in their escape response, exhibiting little or no burst swimming. Other observed effects of exposure to sublethal pH, which may have affected swimming capacity, included increases in the resting levels of blood and muscle ammonia, reduced muscle glycogen stores and reduced muscle ion concentrations.

Journal Article↗
PubMed1995

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History, 20th Century↗
PubMed1995

Clinical experience with the long-term use of 1% apraclonidine. Incidence of allergic reactions.

OBJECTIVE: To identify the incidence and characteristics of allergic reactions associated with the long-term use of 1% apraclonidine hydrochloride. METHODS: We undertook a retrospective analysis of 64 patients receiving long-term 1% apraclonidine therapy at the University of California-San Francisco Glaucoma Service. Patients were excluded if the duration of treatment was less than 2 weeks. Demographic data, initial intraocular pressure response, and incidence and characteristics of allergic reactions were obtained through chart review. Student's t test and chi 2 analysis were used to analyze the demographic data, and Kaplan-Meier survival analysis was used to estimate the long-term incidence of local reactions. RESULTS: Sixty-four patients met the criteria for the study. Of these, 31 (48%) developed an allergic reaction (responders) that led to discontinuation of treatment with the medication, with a mean latency of 4.7 months. Mean follow-up was 13.3 months. Patients free of local reactions (nonresponders) for at least 10 months were able to successfully continue apraclonidine use. Responders tended to be older and female. CONCLUSIONS: Our data are specific for the 1% preparation; however, physicians prescribing apraclonidine on a long-term basis should be aware of possible allergic reactions. A substantial percentage of patients developed this side effect, but most tolerated the medication for up to 4 months, and those without a local reaction after 10 months appeared to be able to continue apraclonidine use indefinitely. This allergic reaction is likely related to the adrenergic agent itself, and not to preservatives.

Adrenergic alpha-Agonists↗
PubMed1995

The in vivo pharmacological profile of a 5-HT1 receptor agonist, CP-122,288, a selective inhibitor of neurogenic inflammation.

1. The aim of the present study was to investigate the in vivo pharmacological profile of CP-122,288, an indole-derivative with a conformationally restricted N-methylpyrrolidinyl basic side chain in the C-3 position. This C-3 substituent structurally differentiates CP-122,288 from the 5-HT1D receptor agonist sumatriptan, which possesses an N,N-dimethylaminoethyl group. [Formula: see text] 2. When administered prior to electrical stimulation of the trigeminal ganglion, CP-122,288 (0.3-300 ng kg-1, i.v.) produced a dose-related inhibition of plasma protein extravasation in rat dura mater (minimum effective dose, MED, 3 ng kg-1 i.v., P < 0.05; maximal inhibition of plasma extravasation at 30 ng kg-1 i.v., P < 0.01). Sumatriptan produced a similar inhibition of plasma leakage in the dura, but at much higher dose levels (MED, 100 micrograms kg-1 i.v., P < 0.05). Thus, CP-122,288 is of the order of 10(4) fold more potent than sumatriptan. 3. At all doses tested, CP-122,288 did not inhibit plasma protein extravasation measured in extracranial tissues such as the lower lip, eyelid, and conjunctiva. 4. In a separate series of studies in the anaesthetized rat, CP-122,288 (0.003-3 micrograms kg-1 i.v.) produced no change in either heart rate or mean arterial blood pressure, thus demonstrating that doses of CP-122,288 which inhibit plasma protein leakage in rat dura, are devoid of hemodynamic effects. 5. Following a 5 min period of electrical stimulation of the trigeminal ganglion, a 20 min period of sustained neurogenically-driven plasma extravasation, occurring in the absence of electrical stimulation, was initiated. By administration of the compound 5 min after completing the phase of electrical stimulation, this protocol permitted the evaluation of the activity of CP-122,288 on an ongoing and established inflammatory event. CP-122,288 (30 and 300 ng kg-1, i.v., P < 0.01 and P < 0.05, respectively) produced a complete inhibition of plasma protein leakage which was consistent with its effects when administered prior to trigeminal ganglion stimulation. 6. In the anaesthetized dog, CP-122,288 and sumatriptan, at 1-300 micrograms kg-1, i.v., produced a dose-dependent reduction in carotid arterial blood flow and coronary arterial diameter. These data demonstrate that sumatriptan inhibits neurogenic inflammation in the rat (MED, 100 micrograms kg-1, i.v.), and produces vasoconstriction in the dog, over a similar dose-range. Interestingly, doses of CP-122,288 that inhibit neurogenic inflammation in rat dura mater (0.3-300 ng kg-1) were demonstrated to be devoid of vasoconstrictor activity in either the carotid or coronary vascular beds of dog. 7. These data demonstrate that in the rat, CP-122,288 is a highly potent and selective inhibitor of neurogenic inflammation in intracranial tissues, at doses which are devoid of vasoconstrictor activity in dog. Potentially, CP-122,288 may be of use for the acute treatment of migraine, without the risk of cardiovascular side-effects.

Anesthesia↗
PubMed1995

Natural history of bacteriuria in women with primary biliary cirrhosis and the effect of antimicrobial therapy in symptomatic and asymptomatic groups.

Primary biliary cirrhosis (PBC) patients have an increased incidence of recurrent urinary tract infection compared with patients with other chronic liver diseases. The course of significant asymptomatic and symptomatic bacteriuria in women with PBC was evaluated: consecutive patients were screened for bacteriuria at their outpatient appointments. Bacteriuric patients who were asymptomatic (n = 21) were randomised to receive antimicrobial therapy (n = 11), or no therapy (n = 10). Bacteriuric patients who were symptomatic (n = 13) were treated. All were followed up by weekly dipslide examination of urine. The course of bacteriuria in the 13 symptomatic and 11 asymptomatic treated patients was similar in terms of the medium interval between successive infective episodes (three and four weeks respectively), the number of relapses (six and seven) and reinfections (14 and 18). Most untreated asymptomatic patients became abacteriuric spontaneously but became reinfected with a different organism during the study period. A separate group of 24 PBC patients with no previous bacteriologically proved urinary tract infection was followed weekly in a similar fashion: seven (29%) became bacteriuric for two to four weeks during a three month period. This study suggests that treatment of recurrent bacteriuric episodes in PBC patients does not alter the natural history of their infection. The long term implication of periodically infected urine in these patients is currently unknown.

Adult↗
PubMed1995

Pulsatile insulin secretion accounts for 70% of total insulin secretion during fasting.

The purpose of the present study was to determine the contributions of discrete insulin secretory bursts vs. basal insulin release to total insulin secretion in vivo. Quantification of the partitioning of pulsatile and basal insulin secretion is complicated by physiological delivery of these pulses into the portal vein and the absence of validated methods of measuring the rates of pulsatile and basal insulin secretion in vivo. We therefore 1) developed a canine model with chronically implanted portal vein catheters, 2) validated an established deconvolution technique as well as a novel direct catheterization technique (Clustcath) for measurement of pulsatile and nonpulsatile insulin secretion rates in this model, and 3) applied these methods to study insulin secretion in the overnight-fasted dog in vivo to determine the contribution of pulsatile vs. basal insulin secretion to total rates of endogenous insulin secretion. Rates of total, pulsatile, and nonpulsatile endogenous insulin secretion measured by Cluscath closely parallel those measured by deconvolution analysis (54 +/- 15 vs. 51 +/- 11, 38 +/- 12 vs. 36 +/- 11, and 16 +/- 4 vs. 14 +/- 4 pmol/min, respectively). Clustcath and deconvolution indicated that the majority of insulin was secreted as pulses (70 +/- 6 and 66 +/- 7%, respectively). These data infer that any process that selectively decreases the pulsatile component of insulin secretion (e.g., diabetes mellitus) will likely have a major impact on total insulin secretion.

Animals↗
PubMed1995

Physiological modelling of oxygen consumption in birds during flight

This study combines data on changes in cardiovascular variables with body mass (Mb) and with exercise intensity to model the oxygen supply available to birds during flight. Its main purpose is to provide a framework for identifying the factors involved in limiting aerobic power input to birds during flight and to suggest which cardiovascular variables are the most likely to have been influenced by natural selection when considering both allometric and adaptive variation. It is argued that natural selection has acted on heart rate (fh) and cardiac stroke volume (Vs), so that the difference in the arteriovenous oxygen content (CaO2-Cv¯O2) in birds, both at rest and during flight, is independent of Mb. Therefore, the Mb exponent for oxygen consumption (V(dot)O2) during flight can be estimated from measurements of heart rate and stroke volume. Stroke volume is likely to be directly proportional to heart mass (Mh) and, using empirical data, values for the Mb coefficients and exponents of various cardiovascular variables are estimated. It is concluded that, as found for mammals, fh is the main adaptive variable when considering allometric variation, although Mh also shows a slight scaling effect. Relative Mh is likely to be the most important when considering adaptive specialisations. The Fick equation may be represented as: (V(dot)O2)Mbz = (fh)Mbw x (Vs)Mbx x (CaO2 - Cv¯O2)Mby , where w, x, y, z are the body mass exponents for each variable and the terms in parentheses represent the Mb coefficients. Utilising this formula and data from the literature, the scaling of minimum V(dot)O2 during flight for bird species with a 'high aerobic capacity' (excluding hummingbirds) is calculated to be: 166Mb0.77&plusmn;0.09 = 574Mb-0.19&plusmn;0.02 x 3.48Mb0.96&plusmn;0.02 x 0.083Mb0.00&plusmn;0.05 , and for hummingbirds (considered separately owing to their unique wing kinematics) it is: 314Mb0.90&plusmn;0.22 = 617Mb-0.10&plusmn;0.06 x 6.13Mb1.00&plusmn;0.11 x 0.083Mb0.00&plusmn;0.05 . These results are largely dependent on the cardiovascular values obtained from pigeons flying near to the minimum power speed of 10 m s-1, but would appear to provide realistic values. Both the measured and the estimated V(dot)O2 for hummingbirds appear to scale with a larger Mb exponent than that for all other birds, and it is suggested that this is as a result of the larger Mb exponent for flight muscle mass as the larger species of hummingbirds try to maintain hovering performance. It is proposed that estimated V(dot)O2 for birds during flight, which is based on Mh in combination with estimates of fh and CaO2-Cv¯O2, gives an indirect measure of relative aerobic power input and, when corrected for the estimated scaling influences of the mechano-chemical conversion efficiency and lift generation with respect to Mb, may be a useful indicator of the relative capacity of the muscle to sustain power output and lift production during flight.

Journal Article↗
PubMed1995

Plasma ammonia concentration in brown trout in soft acidic water and its relationship to decreased swimming performance

Adult brown trout (300&shy;600 g) were acclimated for 2 weeks to an artificial soft water (Ca2+, 50 &micro;mol l-1) and maintained at either 5 &deg;C (October to March) or 15 &deg;C (May to August). Following insertion of a cannula into the dorsal aorta under MS-222 anaesthesia and a recovery period of 2 days, the fish were exposed to a 4 day episode of sub-lethal copper levels at pH 5 or kept at control conditions of pH 7 without copper. The copper concentrations had been predetermined by toxicity testing and were approximately 0.47 &micro;mol l-1 at 5 &deg;C and 0.08 &micro;mol l-1 at 15 &deg;C. At 5 &deg;C, a group of fish was also exposed to approximately 0.08 &micro;mol l-1 copper at pH 5. Plasma total ammonia (Tamm) concentration was significantly elevated by exposure to copper and pH 5. In resting trout exposed to the appropriate sub-lethal copper concentration at pH 5, Tamm was six and 7.5 times greater at 5 and 15 &deg;C, respectively, than those of control trout at the respective temperatures. Although unconfirmed, an elevation of ammonia production alone seems unlikely to account for such substantial increases. From previous studies, there is little evidence of impairment of respiratory gas exchange in trout exposed to these copper concentrations and yet, in the acidic test waters, the gradient of NH3 partial pressure between fish and water was 5.5&shy;6 times greater than that under control conditions. Swimming performance determined by the critical swimming speed (Ucrit) was reduced by copper and acid exposure, and a significant relationship existed between Ucrit and the plasma ammonia concentration of exercised trout. Ammonium ions influence several key enzymes involved in energy metabolism, and elevated ammonia levels might, therefore, reduce the capacity of muscle to exercise. Alternatively, ammonia may have affected the nervous coordination of exercise either centrally or by disrupting peripheral motor innervation.

Journal Article↗
PubMed1995

Detection of M2 antibodies in patients with recurrent urinary tract infection using an ELISA and purified PBC specific antigens. Evidence for a molecular mimicry mechanism in the pathogenesis of primary biliary cirrhosis?

Primary Biliary Cirrhosis (PBC) is a chronic liver disease of unknown aetiology. The main characteristic feature of the disease is the presence of circulating antimitochondrial antibodies (AMA) to components (collectively named M2) of the mitochondrial 2-oxo-acid multienzyme complexes; pyruvate, oxoglutarate and branched chain oxo-acid dehydrogenase complexes. As these enzymes are phylogenetically conserved, AMA also exhibit reactivity against a range of microorganisms. PBC patients have an increased incidence of recurrent urinary tract infection (UTI) compared to other chronic liver disease controls. Interestingly, we have recently detected low titre AMA in patients with a history of recurrent UTI but normal liver function using crude bovine heart mitochondrial preparations and immunoblotting techniques. Here we confirm these findings using purified M2 antigens and ELISA. We found that 52% of "normal" subjects with a history of recurrent UTI had AMA specifically to M2 antigens. The percentage was significantly higher than that found for chronic liver disease (19%, p < 0.01) and normal controls (4%, p < 0.001). These results support our hypothesis for molecular mimicry in PBC. We propose that a bacterial trigger, possibly resulting from recurrent UTIs, is responsible for initiating an autoimmune response in a predisposed host because of a cross-reactivity between mitochondrial and bacterial antigens.

Antibody Specificity↗
PubMed1994

Thyrotoxic bone disease in women: a potentially reversible disorder.

OBJECTIVE: To measure changes in spinal and femoral neck bone mineral densities in patients treated for Graves thyrotoxicosis. DESIGN: Cohort study. SETTING: Tertiary care center. PATIENTS: Fifteen women with active Graves thyrotoxicosis. Six patients were premenopausal and nine were postmenopausal. All patients had evidence of thyrotoxicosis as indicated by a raised total serum thyroxine, suppressed serum thyroid-stimulating hormone, and an elevated technetium-99m pertechnetate thyroid scan. A control group of 15 healthy volunteers matched for age, sex, and menopausal status were followed during the same period. MEASUREMENTS: Bone mineral density was measured by dual-energy x-ray absorptiometry at baseline and after 12 months of antithyroid therapy when euthyroidism had been achieved. RESULTS: After 12 months of therapy, total serum thyroxine, total serum triiodothyronine, serum alkaline phosphatase, and serum bone Gla-protein activities had returned to normal in all patients (P < 0.001 for all comparison between initial and final biochemical measurements). During this interval, the mean lumbar spine bone mineral increased from an initial value of 1.01 g/cm2 to 1.07 g/cm2, an increase of 6.6% per year (95% CI, 3.6% to 9.6%) (P < 0.001 compared with controls). Increases in femoral neck (1.2%/y; CI, -2.1% to 4.5%; P = 0.2 compared with controls) and femoral trochanter bone mineral (3.2%/y; CI, 2.4% to 8.7%; P = 0.2 compared with controls) were not statistically significant. Using forced-entry multiple regression analysis, the severity of the thyrotoxicosis was independently associated with the percentage increment in lumbar spine bone mineral density after 12 months of antithyroid therapy. CONCLUSION: Effective treatment of Graves thyrotoxicosis was associated with increases in lumbar spine and femoral neck bone mineral. Although the changes in bone mineral were modest, our data suggest that thyrotoxic bone loss may be a reversible disorder.

Absorptiometry, Photon↗
PubMed1994

Natural history of indeterminate pigmented choroidal tumors.

PURPOSE: The purpose of this study is to delineate the natural history of indeterminate pigmented choroidal lesions and identify parameters from the initial visit that correlate with lesion enlargement. METHODS: The authors retrospectively reviewed the records of all patients with indeterminate pigmented choroidal lesions seen in consultation at the Ocular Oncology Unit at the University of California, San Francisco, after 1975. Clinical examination, fundus photography, fluorescein angiography, and ultrasound data were examined. Investigators masked to outcome coded sequential parameters of each of these modalities. Data were analyzed using both univariate and multivariate censored data techniques. RESULTS: Of 293 lesions, 98 grew. The 5-year actuarial rate of growth was 36%. Greater tumor thickness, presence of symptoms, orange pigment, internal quiet zone on B-scan, and hot spots on fluorescein angiography all were significant predictors of tumor enlargement (relative risk of detectable tumor growth, > 1.8). Risk scores were calculated, and subsets with higher probability of future growth were identified. In five of the patients with growing lesions, metastatic disease developed after a median posttreatment follow-up period of 51 months. CONCLUSION: Most small indeterminate pigmented lesions can be followed safely by serial observation and ancillary testing. The authors identified models based on data from the initial visit that can be used as an adjunct to planning tumor management.

Adult↗
PubMed1994

A comparative study of the safety and efficacy of dysprosium-165 hydroxide macro-aggregate and yttrium-90 silicate colloid in radiation synovectomy--a multicentre double blind clinical trial. Australian Dysprosium Trial Group.

The aim of our study was to compare the safety and efficacy of a new preparation, Dysprosium-165 Hydroxide Macroaggregate (165Dy) with Yttrium-90 Silicate (90Y) for radiation synovectomy of the knee in patients with RA and OA. A multicentre double blind clinical trial with subjects randomized to receive 165Dy or 90Y was undertaken in Sydney, Melbourne and Perth. Seventy knees of 59 patients were studied, using as clinical end point measurements, pain in the knee on walking, pain in the knee at rest and stiffness in the knee after rest. Cytogenetic damage, knee retention and extra-articular spread of the radionuclide to regional lymph nodes, liver, urine and blood were evaluated. There was no significant difference in clinical response in the two treatment groups for either RA or OA. Chromosomal changes occurred with equal frequency and the knee retention and extra-articular leakage of radiocolloids to regional lymph nodes and liver were comparable in the two groups. For radiation synovectomy of the knee, 165Dy is at least as safe and as effective as 90Y and has the advantage of a short half-life (2.334 h) and hence requires a shorter period of post-injection immobilization and hospitalization.

Aged↗