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Biomedical subjects

C M Harris

Publications and source records attributed to C M Harris.

At least 181 records · Page 10Linked to original sources
PubMed1985

The estimation of microbial biomass.

Methods that have been used to estimate the content, and in some cases the nature, of the microbial biomass in a sample are reviewed. The methods may be categorised in terms of their principle (physical, chemical, biological or mathematical/computational), their speed (real-time or otherwise) and the amount of automation/expense involved. For sparse populations, where the output signal is to be enhanced by growth of the organisms, physical, chemical and biological approaches may be of equal merit, whilst in systems, such as laboratory and industrial fermentations, in which the microbial biomass content is high, physical methods (alone) can permit the real-time estimation of microbial biomass.

Bacteria↗
PubMed1985

Case history questionnaires in the study of doctors' use of resources. Are they measuring what we want?

A set of 15 self-administered case histories were developed, each consisting of a short case followed by a standard format on which desired tests were checked. After pilot testing the case histories within a group of doctors, the authors selected the ten cases with the highest item-total correlations that also provided a broad clinical spectrum. Using a different group of 19 doctors, test-ordering on the questionnaire was compared with actual test-ordering in clinical practice. Questionnaire test-ordering did not reflect practice behavior; in fact, the relationship tended to be inverse (r = -0.43: P less than 0.10). Adjusting for case-mix variation by including only those practice cases with diagnoses similar to questionnaire cases did not improve its performance (r = -0.50: P less than 0.05). These findings suggest that test-ordering on case history questionnaires may not reflect actual practice behavior. Conclusions about test-ordering behavior and management strategies to alter it should not be based on results from questionnaires that have not been validated against actual practice.

Clinical Laboratory Techniques↗
PubMed1985

The stabilization of vancomycin by peptidoglycan analogs.

The glycopeptide antibiotic vancomycin is unstable in solution. It undergoes a rearrangement involving the conversion of an asparagine residue to isoaspartate to give an antibiotically inactive species, CDP-I. Peptide analogs of bacterial peptidoglycan, such as Ac-D-Ala-D-Ala and di-Ac-L-Lys-D-Ala-D-Ala bind to vancomycin and stabilize the antibiotic against degradation and consequent loss of activity. Protection by peptide is effective even under prolonged heating at 80 degrees C or steam sterilization (30 minutes, 10(4) kg/m2).

Chemical Phenomena↗
PubMed1985

Prescribing--a case for prolonged treatment.

In an earlier study it was shown that general practitioners changed some of their prescribing habits when they were given detailed analyses of their prescriptions every six months for two years and provided with opportunities to discuss the information with participating colleagues. A follow-up study of the same doctors two years later revealed that most of the effects of the intervention had disappeared, though the increase in generic prescribing persisted. It is concluded that a more sustained intervention is needed to bring about more lasting change.

Drug Prescriptions↗
PubMed1984

A comparison of ambulatory test ordering for hypertensive patients in the United States and England.

We compared British and American patterns of ambulatory testing for chronic uncomplicated hypertensive patients by examining test use for 351 American patients cared for by 30 community-based internists in Massachusetts and 511 British patients cared for by 18 general practitioners in Greater London. For each of 13 tests examined, utilization was equal or higher for American patients. Significantly more ECGs, chest roentgenograms, plain roentgenograms (other than chest roentgenograms), blood cell counts, urinalyses, cervical cytological tests, barium enema examinations, and intravenous pyelograms were ordered. Differences ranged from four to 40 times higher in the United States. This investigation documents a marked difference in test use. Further study is needed to determine whether the conservative use of diagnostic services adversely affects patient outcomes or represents a more cost-effective form of care.

Clinical Laboratory Techniques↗
PubMed1984

Influence of patient characteristics on test ordering in general practice.

Information regarding all consultations was collected in seven general practices for one year. From these data we report on the use of laboratory tests and its association with patient characteristics--including social class, age, sex, and diagnosis--and with which doctor was consulted. Most of the requests were for technically simple tests of low cost. There was a noticeable variation in the use of tests with regard to all patient characteristics. Diagnosis, identity of doctor, age of patient, and social class were each shown by multivariate techniques to be independently related to use of tests. Whereas fewer tests were used per consultation for social classes III-V compared with other social classes, more were used per patient per year for these same groups, reflecting in part the higher consultation rates of social classes III-V. Variation in diagnoses fully accounted for the greater test ordering for women. Nearly two thirds of all tests were ordered for 10% of all patients who consulted and 7% of all registered patients. The results of our analysis suggest that this concentration is determined primarily by those patient characteristics most indicative of medical need and by which doctor is providing care.

Adolescent↗
PubMed1984

Mental illness in inner London.

From the perspective of general practice, hospital data indicating that the prevalence of mental illness is much higher in inner London than elsewhere in Britain may be misleading. A study in five inner London practices found morbidity patterns for mental disorder similar to those recorded in a national survey.

Anxiety Disorders↗
PubMed1984

Characteristics of saccades in human infants.

Infants (14-151 days) and adults were shown two-dimensional geometric forms or stimuli from a set of highly textured patterns. Their eye movements were recorded by an infrared corneal reflection eye movement recorder as they freely scanned the stimuli. For both infants and adults, linear relationships were found between the peak velocities of fast eye movements and their amplitudes (main sequences). Infants viewing texture stimuli had main sequences with slopes comparable to those of adults. Infants viewing simple geometric forms made slower saccades. They also showed more eye movement oscillations which analyses showed were probably back-to-back saccades. Both the slower saccades and saccadic oscillations were attributed to factors related to the attentional value of the stimuli.

Adolescent↗
PubMed1984

Withdrawal from morphine generalizes to a pentylenetetrazol stimulus.

Rats trained to discriminate pentylenetetrazol (PTZ) from saline in a two-lever food-reinforced operant task were given a three-day course of morphine, 15 to 45 mg/kg tid, ip. On the third day naloxone produced dose-dependent generalization to the PTZ stimulus, with 66% of subjects selecting the PTZ lever after the highest dose (0.32 mg/kg). Following termination of morphine injections, generalization of spontaneous withdrawal was tested. Approximately 50% of subjects selected the PTZ lever at 24 and 48 hrs after the last morphine, and by 96 hrs the percentage of subjects selecting the PTZ lever had dropped to 11%. Rats that chose the PTZ lever at 48 hrs were given diazepam, 5.0 mg/kg, which blocked the PTZ-like stimulus. These data demonstrate that morphine withdrawal produces a stimulus with PTZ-like characteristics which can be blocked by an anxiolytic, and they suggest that the PTZ discrimination may have general utility for investigating drug dependence and withdrawal in animals.

Animals↗
PubMed1984

Reassessing morphine effects in cats: I. Specific behavioral responses in intact and unilaterally brain-lesioned animals.

Behavioral responses to single low doses of morphine (0.5-3.0 mg/kg IP) were measured in intact cats and in cats with removal of one cerebral hemisphere or one caudate nucleus. Responses were dose-dependent and formed 3 stages: (1) autonomic stage (0-15 min postdrug): with vocalization, salivation, licking, swallowing, retching and vomiting; (2) quiet stage (15-60 min postdrug): sitting, fixed gaze, mydriasis, and pricked pinnae; (3) head movement stage (from 30-60 min postdrug and decreasing by the 5th hr): fully aroused but mostly sitting; showing discrete, complex head movements of a visual-tracking type with pouncing/avoidance paw movements, and with irregular, dose-dependent bouts of rocking, pivoting, and backing. Sleep, grooming, micturition and defecation were suppressed. In hemispherectomized cats the frequency of head movements was increased only towards the side of the ablation, and there was a strong bias for body turning to that side together with a significant bias to move the ispilateral paw. None of these biases were significant in cats with a unilateral caudate ablation. We conclude that the cat is an excellent model for behavioral morphine studies when dose levels below those inducing "feline mania" are used. CNS sites underlying these responses are discussed.

Animals↗
PubMed1984

Reassessing morphine effects in cats: III. Responses of intact, caudate nuclei-lesioned and hemispherectomized animals following chronic administration and precipitated withdrawal.

Behavioral response to low doses of morphine (2.0 to 3.0 mg/kg, IP) administered for up to 15 days, and responses to subsequent naloxone challenges, were measured in intact, unilaterally and bilaterally caudate-lesioned (acaudate) cats, and in hemispherectomized cats using a video time-sampling method. For all groups minor tolerance to posture and movement activation patterns was seen, with a reciprocal increase in motor relaxation, which was somewhat more marked for acaudate cats. In contrast to this weak tolerance, all cats showed strong, typical withdrawal manifestations at the beginning of abstinence and a "mini withdrawal" could still be precipitated 15-30 days later when morphine was no longer detectable in the blood. The cats with the unilateral lesions showed whole body turning toward the lesioned side after morphine and away from the lesioned side following naloxone. Only hemispherectomized and acaudate animals showed significant physical deterioration (e.g., weight loss, decreased activity). The comparisons between weak tolerance development versus strong physical dependence and the possible mechanisms involved in shifting the turning biases are discussed. The potential of the cat as a model for studying opiate effects is stressed.

Animals↗
PubMed1984

Seasonal variations in depression and osteoarthritis.

Seasonal variations in consultations for depression and osteoarthritis were discovered in the 1980 morbidity data of five London practices with a total of 32,524 patients. Depression showed a bimodal pattern similar to that described from hospital data and national suicide statistics, but not previously recorded from general practice. Osteoarthritis also showed a bimodal pattern, with peaks in spring and autumn; this came as a surprise and needs confirmation from other studies. It may reflect the known tendency of rheumatic symptoms to become worse when relative humidity and other climatic variables are at their most changeable.The number of patients recorded in the year as having both osteoarthritis and depression was significantly smaller than would have been expected by chance. This finding is probably due to selective attention in the consultation, since it is unlikely that one condition protects a patient from getting the other.

Depression↗
PubMed1983

Effect of lecithin on memory in normal adults.

In a double-blind, placebo-controlled, crossover study of the effect of lecithin on memory test performance, nine normal paid volunteers (age range = 22-55 years) took single oral doses of placebo and lecithin (20 g) 5 hours before cognitive testing. Lecithin raised plasma choline levels during the test session to nearly double the placebo levels, but a categorized serial learning task, a word recognition task, a paired associates learning task, and a test of retrieval by category demonstrated no significant change in memory performance. Lecithin did not selectively enhance memory for low-imagery words. Lecithin also had no effect on psychomotor speed.

Adult↗