Search PubMed⌕ Search

Biomedical subjects

M Durkin

Publications and source records attributed to M Durkin.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effect of PaCO2 on cerebral blood flow distribution during halothane compared with isoflurane anaesthesia in the rat.

In order to examine anaesthetic effects on the distribution of cerebral blood flow (CBF) during normo- and hypocapnia, male adult Sprague-Dawley rats were allocated randomly to four groups in a 2 x 2 factorial design, using PaCO2 value and anaesthetic agent as between-group factors. Animals were anesthetized with either 1.38% isoflurane (inspired) or 1.05% halothane (inspired) and the lungs ventilated mechanically at either normocapnia (PaCO2 5.1-5.6 kPa) or hypocapnia (PaCO2 3.1-3.3 kPa) for 1 h. CBF was measured using 14C-iodoantipyrine autoradiography. Local CBF in selected cortical and subcortical regions of interest and area-weighted mean global CBF were calculated. Data were compared by analysis of variance. Normocapnic (mean (SE] CBF for halothane (n = 6) and isoflurane (n = 7) was 120 (8) ml/100 g min-1 (PaCO2 5.6 (0.49) kPa) and 117 (9) ml/100 g min-1 (PaCO2 5.4 (0.5) kPa), respectively. Hypocapnic CBF for halothane (n = 6) and isoflurane (n = 6) was 82 (7) ml/100 g min-1 (PaCO2 3.3 (0.12) kPa) and 82 (6) ml/100 g min-1 (PaCO2 3.2 (0.12) kPa), respectively. Hypocapnia reduced global CBF for both groups by 30% (P less than 0.001), but there was no difference between anaesthetic agents (P greater than 0.8). Hypocapnia decreased CBF in all local structures examined. Although subcortical structures had similar CBF at both normocapnia and hypocapnia, CBF in three cortical samples was greater (P less than 0.05) in both the normocapnic and hypocapnic halothane groups than the corresponding isoflurane groups. The CBF reactivity to changes in PaCO2 was similar for both agents (approximately 2 ml/100 g min-1 mm Hg). (ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Localized alterations of dopamine receptor binding in rat brain by repeated electroconvulsive shock: an autoradiographic study.

The effects of repeated electroconvulsive shock (ECS) on binding parameters of D1 and D2 type dopamine (DA) receptors were investigated in different brain regions of male rats using quantitative autoradiography. D1 binding was studied with [3H]SCH 23390 as the ligand and D2 binding with [3H]spiroperidol. The distribution patterns of both D1 and D2 receptor sites were in good agreement with previously published reports. Repeated ECS induced upregulation of D1 receptors in the olfactory tubercle, the endopiriform nucleus and the substantia nigra without appreciably affecting D1 binding sites in the striatum, n. accumbens or in other brain regions containing D1 binding sites. Upregulation of D2 binding sites, after ECS, was seen in the accumbens, the olfactory tubercle, the amygdaloid nuclei, the claustrum and the endopiriform nucleus, but not in the caudate-putamen or in other brain regions containing D2 binding sites. The present finding that repeated ECS can selectively upregulate DA receptor binding sites in discrete brain areas, including limbic structures, renders important support to a large number of previous studies that demonstrated effects of repeated ECS on DA receptor function in behavioral models.

Animals↗
PubMed1990

An autoradiographic study of the uptake and distribution of iron by the brain of the young rat.

Rats aged 15, 28, or 42 days were injected intraperitoneally with iron-59 and were sacrificed at varying intervals. Total acquisition of iron-59 by the brain, when compared to levels of iron-59 in blood sampled 48 h after injection, diminished with increasing age at injection. Cerebral levels of iron-59 in animals injected at age 15 days did not change with postinjection interval despite rapidly decreasing serum levels of iron-59. Thus, iron acquired by the brain early in postnatal development becomes sequestered in that organ. However, autoradiography of the brains of animals injected at age 15 days showed definite changes over time in the anatomic distribution of the isotope. This suggests that mechanisms may exist for the translocation of iron from one area of the brain to another.

Aging↗
PubMed1990

Validity of the 'Ten Questions' for screening serious childhood disability: results from urban Bangladesh.

A survey of 2576 children aged two to nine years was carried out in Dhaka, Bangladesh, as part of a collaborative study to test the validity of a questionnaire (the Ten Questions) for screening severe childhood disabilities in community settings. Approximately 7% of the children were positive on the screen and this rate was slightly higher in boys than girls. The sensitivity, specificity and negative predictive value of the Ten Questions were perfect or nearly perfect for severe and moderate (serious) disabilities. The positive predictive value was only 22% for serious disabilities, but 70% of children classified as false positives were found to have mild disabilities or other conditions (such as ear infections) for which early detection and treatment could be beneficial. No major age or gender differences in the validity of the questionnaire were apparent, but this finding needs additional study and confirmation with studies based on larger samples. In general, the results indicate that the Ten Questions is a valid tool for screening serious disabilities in children and can potentially improve the efficiency of health services by reducing the number of children requiring attention from professionals. Future studies using the Ten Questions should foster greater attention to the dimensions of childhood disability as a public health problem in the less developed world.

Bangladesh↗
PubMed1990

Nimodipine does not increase cerebral blood flow during hypocapnia in the rat.

Nimodipine is a calcium entry blocker that shows promise in the therapy for cerebral ischemia. This study was undertaken to examine the interaction of nimodipine with the use of hypocapnia to control cerebral blood volume by reduction in cerebral blood flow (CBF), as might be applicable to patients undergoing anesthesia for neurosurgical procedures. Male adult Sprague-Dawley rats were anesthetized with pentobarbital 50 mg/kg i.p. and were mechanically ventilated at either normocapnia (Paco2 35-40 mm Hg) or hypocapnia (Paco2 23-25 mm Hg). Animals were randomized into four experimental groups in a 2 x 2 factorial design, employing Paco2 level and drug group as between-group factors: vehicle plus normocapnia (group 1, n = 6), nimodipine plus normocapnia (group 2, n = 7), vehicle plus hypocapnia (group 3, n = 6), and nimodipine plus hypocapnia (group 4, n = 6). Nimodipine (1 mug/kg/min) or vehicle was administered i.v. for a period of 45 min. CBF was then measured using [C]iodoantipyrine autoradiography. Hypocapnia decreased global CBF (p <0.0001) and nimodipine increased CBF (p <0.05). Although nimodipine increased global CBF (p <0.05) during normocapnia (89 +/- 8 versus 61 +/- 4 ml/100 g/min), during hypocapnia there was no significant difference between nimodipine and vehicle (45 +/- 3 versus 40 +/- 2 ml/100 g/min). Hypocapnia decreased local CBF in all structures examined, whereas nimodipine increased local CBF in some, but not all structures. In this model, prior institution of hypocapnia prevented nimodipine-induced global CBF increases.

Journal Article↗
PubMed1990

Photoresistive measurement of the Pavlovian conditioned eyelid response in human subjects.

An inexpensive technique is described for measuring eyelid closure during classical (Pavlovian) conditioning experiments. This technique employs a Coulbourn Instruments Co. densitometric device that focuses a beam of infrared light on the cornea. Reflection of the light is interrupted by the eyelids when they are closed, which is sensed by an infrared detector. The latter causes a voltage change to occur, which can then be measured in a variety of ways. Details of both the hardware required and software developed for this purpose are described.

Arousal↗
PubMed1990

Esophageal motor disorder in alcoholics: result of alcoholism or withdrawal?

Both acute and chronic ethanol consumption may cause esophageal dysmotility. In order to systematically evaluate the effect of ethanol on esophageal motility, we studied esophageal motility in 13 healthy subjects before and following acute intravenous administration of 0.8 g/kg ethanol and in chronic alcoholics within 6 hr of their last drink (n = 6) and following 24 to 48 hr of abstinence when signs of withdrawal were present (n = 13). Withdrawing alcoholics were also restudied after intravenous administration of 0.8 g/kg ethanol. Ethanol transiently decreased lower esophageal sphincter pressure (LESP) and inhibited LES relaxation in all control subjects; this inhibitory effect of ethanol on LESP in alcoholics was significantly less, indicating the development of tolerance. Ethanol moderately decreased esophageal contraction amplitude (ECA) in 10 of 13 controls and prolonged duration of contractions in all but had no effect on velocity of esophageal contractions. In contrast, ECA was significantly elevated in both groups of alcoholics, but this was significantly more marked in withdrawing alcoholics. Ethanol infusion returned ECA toward normal values in withdrawing alcoholics. Abnormal motility was noted in three intoxicated alcoholics and 10 (77%) withdrawing alcoholics. This included nutcracker esophagus in five and hypertensive LES in two. These data indicated that (1) esophageal motor dysfunction is common in alcoholics; (2) acute ethanol administration decreases LESP and esophageal contraction amplitude, whereas chronic ethanol consumption and withdrawal from ethanol increases ECA. This suggests development of a compensatory mechanism in chronic alcoholics leading to high pressure esophageal contractions during withdrawal.

Adult↗
PubMed1988

Ayurvedic treatment for jaundice in Nepal.

This paper describes beliefs and practices associated with jaundice and its treatment by ayurvedic physicians (vaidyas) in Kathmandu. It documents continuity of ancient ayurvedic ideas and practices as well as syncretism between ayurvedic and allopathic (Western, biomedical) traditions in modern Nepal. Popular beliefs about the cause of jaundice appear to have evolved to fit therapeutic practices adopted by vaidyas from allopathy. An implication of this finding is that beliefs about causation do not necessarily precede and channel therapeutic choices; they may also function to rationalize and provide meaning to experiences of illness and therapy. The data also suggest a number of hypotheses about the efficacy of ayurvedic treatment for jaundice.

Attitude to Health↗
PubMed1987

Mild mental retardation and severe mental retardation compared: experiences in eight less developed countries.

Frequencies of Severe Mental Retardation (SMR) and Mild Mental Retardation (MMR) were obtained from pilot surveys of severe childhood disability in 8 less developed countries. Approximately 1,000 children aged 3 to 9 years were surveyed in each location. The surveys used a Ten Question (TQ) door-to-door interview, usually of the mother, as a screening procedure and a systematic medical and psychological assessment for the diagnosis. Diagnostic categories of SMR (IQ less than or equal to 55) and MMR (IQ greater than 55, less than or equal to 70) were assigned by well trained local psychologists, using formal and informal techniques of assessment. Contrasting frequencies and distributions for MMR compared with SMR are shown for each location. No consistent pattern for MMR versus SMR emerged, neither regarding frequency, male/female ratio, average age nor socio-economic status of household. By contrast, MMR did differ from SMR consistently regarding consanguinity of parents, the presence of associated impairments and the positive report of symptoms at interview. Also, the families of all MR children were lower in SES than comparison families. An interpretation of these findings is offered: the more severely disabled children tend to be assessed as SMR, but so do other children who might, in better circumstances, be assessed as MMR. The relevance of this interpretation is discussed, in terms of assessment and of rehabilitation, and as a guide to further epidemiologic studies.

Asia, Southeastern↗
PubMed1986

"Serious" mental retardation in developing countries: an epidemiologic approach.

In this paper we first present methods and preliminary results of pilot surveys of "serious" mental retardation (IQ less than or equal to 55); the surveys included screening and diagnostic components and were carried out in the less-developed world. Next we discuss two problems raised by these surveys: one is the diagnosis of a case and its clinical dimensions, and the other is the interpretation of prevalence. In the next section we illustrate epidemiological approaches to the analysis of such data, in particular their relevance to prevention. Lastly, we propose that the two-stage survey approach developed in the course of the pilot work can provide a valuable basis for planning and prevention, if certain key conditions can be met.

Bangladesh↗
PubMed1983

Monoclonal antibodies against the GP-2 subunit of laminin.

Two stable rat X mouse hybridoma lines have been isolated. These hybridoma lines produce IgG antibodies directed against the polypeptide portion of the GP-2 subunit of laminin. Antibodies produced by the hybridomas have been shown to be IgG 2b (lambda) and IgG 2a (kappa), respectively. In competition ELISA assays the monoclonal antibodies exhibited different binding affinities for laminin. Furthermore, the two antibodies were partially additive in their reactivity to laminin. Preliminary results also indicate that the antibodies recognized different antigenic determinants in laminin as determined by their reactivity to basement membranes in human and mouse tissues. The monoclonal antibody designated LAM-I stained a broad spectrum of human and mouse tissues; the other monoclonal antibody LAM-II reacted with mouse, but not human tissues. The results indicate that these monoclonal antibodies could be utilized to explore the organization of laminin in basement membranes of different tissues and species.

Animals↗
PubMed1982

Age, typicality, and task effects on categorization of objects.

Object categories seem to have a prototypic structure: a central core of typical members and a periphery of atypical, borderline cases. Our internal concepts of categories must include representations of this prototypic structure. Given such concepts, however, people may use different processing strategies for judging membership in a category. These depend on a person's age and the demands of the categorization task. 3-, 4-, 5-yr.-old, and adult subjects were tested in three different categorization tasks with the same materials. Some of the items to be categorized were central and some were peripheral category members. For 3-yr.-olds there were strong effects of typicality on all three tasks, suggesting that these children were matching items and judging membership in a category on the basis of a wholistic process of comparison. Slightly older children and adults, however, showed differential effects of typicality across tasks, suggesting that they were using various processing strategies in different situations. In some of the tasks, older children and adults may have been using abstraction skills, and for one of the tasks adults may have been using logical classification skills.

Adult↗