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Biomedical subjects

A L James

Publications and source records attributed to A L James.

At least 73 records · Page 4Linked to original sources
PubMed1987

Quantitative measurement of smooth muscle shortening in isolated pig trachea.

Matched porcine tracheal rings were exposed to theophylline and increasing doses of carbachol in Krebs solution. Histological sections of each ring were traced and each of the following dimensions measured: the external perimeter (Pe) and external area (Ae) defined by the outer border of smooth muscle and inner surface of cartilage, and the internal perimeter (Pi) and internal area (Ai) defined by the luminal surface of the epithelium and the muscle length (L) along its outer border. Absolute wall area (WA = Ae - Ai) and relative wall area (PW = WA/Ae) were calculated. Carbachol-treated tracheal ring dimensions were compared with those of their matched theophylline-treated rings. In tracheal rings with intact cartilage, maximal smooth muscle shortening of 44% was achieved with 10(-2) M carbachol. In tracheal rings in which anterior and posterior segments of cartilage were excised, the trachealis muscle passively shortened by 20% and maximal shortening (10(-3) M carbachol) was 57%. Although Ai decreased with maximal smooth muscle shortening, there were no changes in the length of Pi or in WA. These data show that the cartilage in the porcine trachea exerts both a preload that passively stretches the trachealis muscle and an afterload that limits maximal smooth muscle shortening.

Airway Resistance↗
PubMed1987

Airway responsiveness to intravenous and inhaled acetylcholine in the guinea pig after cigarette smoke exposure.

Exposure of conscious guinea pigs to cigarette smoke results in bronchial hyperresponsiveness. To examine the mechanisms involved, we measured airway responses to increasing doses of intravenous or inhaled acetylcholine in guinea pigs exposed to cigarette smoke (n = 20) or to air (n = 20). After exposure the guinea pigs were anesthetized, paralyzed, and studied in a pressure-sensitive body plethysmograph while ventilated through a tracheostomy. Two and 6 puffs of an aerosol of increasing concentrations (0.05 to 500 micrograms/ml) of acetylcholine were delivered via the tracheostomy. Intravenous acetylcholine was delivered in boluses of 0.1 ml of increasing concentrations (0.5 to 50,000 micrograms/ml) via a catheter in an external jugular vein. Pulmonary resistance (RL), dynamic compliance (Cdyn), and heart rate (HR) were measured at baseline (after aerosolized or intravenous saline) and after each dose of acetylcholine. The peak responses to both inhaled and intravenous acetylcholine were rapid in onset (less than 15 s), short-lived (3 to 4 breaths), and were noncumulative. The baseline RL, Cdyn, and HR were not different in the smoke and air exposure groups. In the intravenous acetylcholine group, there were no differences in RL, Cdyn, and HR responses between the air and smoke exposure groups. In the inhaled acetylcholine group, the dose-response curve was shifted to the left (p less than 0.05) and reached a higher maximal response (p less than 0.01) after smoke exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1986

Sensitive reagents for detection of indole production by bacteria.

A number of substituted 4-aminobenzaldehydes were compared with more commonly employed reagents for the detection of indole-producing organisms among the Enterobacteriaceae. Factors such as rate of colour intensity and stability were compared in tests with reference organisms and clinical isolates, and with appropriate concentrations of pure indolic standards. 2-Methoxy 4-dimethylaminobenzaldehyde and 4-N pyrrolidylbenzaldehyde produced immediate and intense red to purple colourations when used in the indole test both in liquid media and on multipoint inoculated plates. Both reagents were considered to be superior to the traditional Ehrlich's reagent and also to 4-dimethylaminocinnamaldehyde which is often used as an alternative.

Benzaldehydes↗
PubMed1986

A sensitive method for demonstration of decarboxylase activities amongst Enterobacteriaceae without use of pH indicators.

Lysine decarboxylase and ornithine decarboxylase activities have been demonstrated in a range of Enterobacteriaceae and related taxa by methods not involving pH indicators. Detection of the diamines produced, cadaverine and putrescine, was achieved by use of reagents based on 5-nitrosalicylaldehyde in the presence of triethanolamine and nickel ions. The method has been shown to be a simple and sensitive means for demonstration of decarboxylase activities when organisms were grown in the presence of the appropriate amino acid. Formation of highly coloured insoluble metal chelates was indicative of enzymatic activity. Results correlated well with existing indicator methods while being superior to the latter with respect to interpretation.

Cadaverine↗
PubMed1986

Symptoms and longitudinal changes in lung function in young seasonal grain handlers.

A total of 119 seasonal grain handlers (mean age 23) were assessed before and towards the end (mean work period 18 days) of the 1983 Western Australian grain harvest to determine if respiratory symptoms that occur with exposure to grain dust are associated with changes in ventilatory capacity or non-specific bronchial reactivity to methacholine. Eighteen per cent of subjects had wheeze, breathlessness, or chest tightness and 18% had cough or sputum production at work. Subjects complaining of wheeze, chest tightness, or breathlessness at work had a significantly greater decline in FEV1 than subjects who did not experience these symptoms (p less than 0.05). Symptoms were not associated with changes in bronchial reactivity. In young grain handlers who develop respiratory symptoms on short term exposure to grain dust changes in FEV1 but not in non-specific bronchial reactivity have been demonstrated.

Adolescent↗
PubMed1985

Adequacy of management and severity of asthma in children attending a summer camp.

To assess the adequacy of therapy in asthma, 46 children with asthma attending a summer camp were asked to complete a questionnaire about their symptoms and the treatment that they had received. Each child's height, weight, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured. According to defined criteria of symptom severity the children were categorized as suffering from severe (48%) or mild (52%) asthma. The mean FEV1/FVC ratio (P less than 0.05) and the mean FEV1 were lower (P less than 0.02) in the children with severe asthma compared with those with mild asthma. In the group with severe asthma, 68% of the children were considered to be receiving suboptimal therapy; 45% had never had their FEV1 or FVC measured. Among those who were receiving suboptimal therapy, 40% had measurable airflow obstruction compared with 17% of children with mild asthma. Because poor management of asthma remains common in children, the need to make doctors and parents aware of the fact that suboptimal therapy may contribute significantly to the morbidity of the condition is emphasized.

Adolescent↗
PubMed1984

Cardiovascular and electrodermal responses to simple stimuli in autistic, retarded and normal children.

Phasic changes in respiratory period, electrodermal activity (EDA), the evoked cardiac response (ECR), and the vasoconstrictive peripheral pulse amplitude response (PPAR), were examined in matched groups of autistic, retarded, and normal children, using repeated presentation of simple visual and auditory stimuli. Analysis as a function of group membership and age indicated that respiratory pause and EDA showed habituation in the retarded and normal groups, but not in the autistic group, with no age effects in any group. PPAR and ECR showed no habituation in any group, but within-group age differences, and a higher mean response level for the autistic subjects. The autistic children did not display the diminution of response level with increased age that was characteristic of both the control groups. These effects were obtained across both modalities. Results could not be attributed to between-group tonic cardiac arousal differences, and were interpreted as further indications of diminished sensitivity to reductions in stimulus novelty, as well as developmental delay, in early-onset psychosis.

Adolescent↗
PubMed1983

Developmental effects in the cerebral lateralization of autistic, retarded, and normal children.

This experiment was designed to determine whether increasing evidence of generalized developmental delay in early-onset psychosis was apparent at a cortical level in autistic children. Using magnitude of dominant ear advantage as an indicator of relative cerebral dominance, unwarned simple reaction time (RT) to monaural presentation of tones was investigated in matched groups of autistic, retarded, and normal children. Analysis of RTs and relative ear advantage as a function of group membership and chronological age indicated that the autistic children showed significant developmental delay in both RT and the establishment of cerebral dominance compared to the control groups. These results thus provide additional evidence of generalized maturational delay at a cortical level in early-onset psychosis, and suggest that the maturational delay of the autistic children is more extensive than the developmental deficits implied by their intellectual impairment.

Adolescent↗
PubMed1981

General maturational lag as an essential correlate of early-onset psychosis.

Evidence for the increasing recognition of maturational lag in addition to intellectual impairment, associated with the syndrome of early-onset psychosis, is presented to indicate that developmental variables play a central role in the behavioral profile of autistic children. The failure of research to give methodological consideration to control of these variables is discussed, and implications for the interpretation of results from experimental studies are outlined. It is suggested that the distinction between controlling not only for mental age but also for chronological age to facilitate the delineation of specific deficits in this syndrome.

Adolescent↗
PubMed1980

Habituation of electrodermal and respiratory responses to visual stimuli as a function of personality differences in affect level.

The relationship between personality level of affect and habituation of electrodermal and respiratory measures was examined in two groups of normal subjects designated Low P (LP) and High P (HP) according to the P scale of the Eysenck Personality Questionnaire. Experiment 1 examined changes as a function of repeated presentation of simple visual stimuli. Group HP displayed reduced habituation rates for both respiratory pause and skin resistance response (SSR), although initial reactivity levels were similar for both groups. This effect was confirmed more strongly in Experiment 2, which utilized a simple counting task and groups separated more widely on P. The implications of these group differences were discussed in relation to the psychophysiological functioning of autistic children.

Adult↗
PubMed1980

A review of psychophysiology in early onset psychosis.

Research on psychophysiological functioning in early onset psychosis is reviewed within the context of etiological formulations stressing perceptual and selective attention abnormalities. Electroencephalographic (EEG) measures, including resting EEG level, alpha blocking, average evoked response, and contingent negative variation, have received most attention in the literature; cardiovascular and electrodermal indices have not been so extensively explored in this group of children. While the nature of differential reactivity in early onset psychosis has not been thoroughly investigated, limited evidence suggests that the central behavioral anomalies associated with the condition may result from abnormal neurophysiological reactivity to sensory stimulation. Further studies of the psychophysiological functioning of these children should yield data useful in the clarification of etiology.

Adolescent↗
PubMed1978

Handedness in autistics, retardates, and normals of a wide age range.

Tests of handedness were carried out with 34 autistic children aged from 4 years 10 months to 18 years 11 months, and with sex-, age-, and IQ-matched retardates and sex- and age-matched normals. There were no significant differences between the groups on frequency of handedness, degree of righthand usage, or degree of dominant-hand usage. There was however a significant increase in the variance of dominant-hand usage from normals and retardates to autistics. These results were taken to indicate that earlier reports of handedness differences in young autistic children may reflect a developmental lag rather than a specific etiology of autism. Some support for this hypothesis was found from a comparison of age-trends between the groups. The relationship of such a developmental delay to the etiology of autism was discussed.

Adolescent↗
PubMed1975

A comparison of the biochemical activities of Bacteroides corrodens and Eikenella corrodens with those of certain other gramnegative bacteria.

Tests carried out on strictly anaerobic and facultatively anaerobic strains of "corrodens" bacteria, showed that although these organisms are relatively inactive biochemically, differentiation can be made on the basis of tests that demonstrate reduction of nitrite, hydrolysis of urea and 1-naphthyl acetate, decarboxylation of lysine and ornithine, and sensitivity to certain selective agents included in culture medium. Plasma was found to be superior to serum in supporting the growth of all "corrodens" bacteria, and a combination of heated and unheated blood added to a nutrient base was shown to yield good growth. Comparative studies are reported with various species of Bacteroides, Haemophilus, Bordetella and related genera.

Amino Acids↗
PubMed1975

Some observations on the effects produced in white mice following the injection of certain suspensions of corroding bacilli.

Strictly anaerobic and facultatively anaerobic strains of "corroding bacilli" failed to produce any pathological symptoms when injected into white mice and no viable organisms could be recovered after 7 days. However, when these same strains were coupled with certain other living bacteria or certain sterile bacterial extracts, lesions developed from which corroding bacilli could be isolated even after 21 days.

Animals↗