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Biomedical subjects

P Butler

Publications and source records attributed to P Butler.

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

A simple method, using 2-hydroxypropyl-beta-cyclodextrin, of administering alpha-chloralose at room temperature.

Effective long term stable anaesthesia is a goal of many drug regimens employed in neuroscience in which procedures carried out are not practical in awake animals. A particular problem is the study of nociceptive mechanisms where good anaesthesia is essential. Similarly studies of cardiovascular or cerebrovascular mechanisms require that normal physiological reflexes be preserved as much as is practical. For non-recovery anaesthesia alpha-chloralose is a good choice since it provides good anaesthesia without excess depression of physiological reflexes. However, alpha-chloralose is sparingly soluble so that its use is not straightforward. We describe the characterisation of a simple procedure to solubilise alpha-chloralose in a solution of 2-hydroxypropyl-beta-cyclodextrin. The resulting solution is stable at room temperature and gives a high concentration of alpha-chloralose making it easier to administer regularly during longer time course experiments.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1997

Stimulation of an intracranial trigeminally-innervated structure selectively increases cerebral blood flow.

The cranial circulation, both extracerebral and cerebral, is innervated by fibers from the trigeminal nerve. This system is known as the trigeminovascular system. The large venous sinuses and dura mater are pain-sensitive and are innervated primarily by branches of the ophthalmic division of the trigeminal nerve. Studies were conducted in the alpha-chloralose anaesthetised cat to examine bulk carotid and cerebral blood flow responses to electrical stimulation of the trigeminal ganglion and superior sagittal sinus. Bulk carotid blood flow was measured using an ultrasonic flow probe and meter applied to the common carotid artery while cerebral blood flow was measured using laser Doppler flowmetry. Vascular resistance was calculated using simultaneously collected blood pressure data. Stimulation of the trigeminal ganglion resulted in a frequency-dependent reduction in both bulk carotid and cerebral vascular resistance. The mean maximal reduction was 39 +/- 5% at 20/s for the carotid bed and 37 +/- 6% at 20/s for the cerebral circulation. Stimulation of the superior sagittal sinus resulted in a frequency-dependent reduction in resistance that involved the cerebral circulation with little effect on bulk carotid resistance. The mean maximum reduction was 37 +/- 6% at 20/s for the cerebral circulation and 11 +/- 3% at 2/s for bulk carotid resistance. The more focused effects of superior sagittal sinus suggest a highly organised somatotopic arrangement of the trigeminal innervation of the cranial circulation. Such a physiological schema fits the known anatomy as reflected by the differential peptidergic innervation from the trigeminovascular system to cranial vessels and may be important in understanding the pathophysiology of migraine, cluster headache and subarachnoid haemorrhage.

Animals↗
PubMed1997

Heat increment of feeding in Brunnich's guillemot

The rate of oxygen consumption (O2), respiratory quotient (RQ) and deep body temperature (TB) were recorded during a single, voluntary ingestion of Arctic cod Boreogadus saida (mean mass 18.9+/-1.1 g, s.e.m., N=13) by five postabsorptive Brunnich's guillemots (thick-billed murre, Uria lomvia). The birds were resting in air within their thermoneutral zone, and the fish were refrigerated to 0-2 degreesC. The rate of oxygen consumption increased by a factor of 1.4 during the first few minutes after ingestion, but there was no significant change in TB. Mean rate of oxygen consumption returned to preingestive levels 85 min after the birds ate the fish. The telemetered temperature of one fish reached TB within 20 min. This suggests that the persistent elevation in O2 over the next hour corresponded to the obligatory component of the heat increment of feeding (HIF) and was not related to heating the fish. Abdominal temperature increases after diving bouts in free-ranging common guillemots (common murre, Uria aalge) are possibly achieved through the HIF, since meals are processed at sea. Of the increase in O2 measured in the laboratory, it is calculated that 30 % is required to heat the fish, while 70 % is due to the HIF. In free-ranging birds, the excess heat provided by the HIF could contribute 6 % of the daily energy expenditure. This suggests that the HIF augments heat production in Uria spp. and thus reduces the energetic cost of thermoregulation.

Journal Article↗
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↗