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Biomedical subjects

M G Hart

Publications and source records attributed to M G Hart.

At least 19 recordsLinked to original sources
PubMed1998

The effect of home training with direct blood pressure biofeedback of hypertensives: a placebo-controlled study.

BACKGROUND: Home training in self-lowering of blood pressure using continuous blood pressure feedback has not previously been reported. Enhancement of laboratory-learned skills was hypothesized on the basis of outcomes from other intellectual, emotional and physical endeavours. OBJECTIVE: To examine the supplementary effect of home blood pressure biofeedback training. DESIGN: Thirty unmedicated, mild hypertensives participated in a randomized, double-blinded, modified contingency placebo-controlled study. METHOD: After suitable screening and baseline blood pressure measurements subjects undertook eight laboratory biofeedback sessions and then 12 home training sessions over 4 weeks using continuous finger blood pressure monitoring. RESULTS: In the laboratory those being administered active therapy (n=16) lowered systolic pressures by 5 +/- 5.4 mmHg compared with a lowering of 4 +/- 4.2 mmHg with placebo (NS). During the fourth week at home lowering for the active group (11 +/- 8 mmHg) was greater than that with placebo (4 +/- 6.2 mmHg, P=0.017). Arm-cuff blood pressures were not statistically different for groups and with time but that of the active group was lower by 9 +/- 15.4/7 +/- 10.2 mmHg, which is a clinically relevant change, after home biofeedback. CONCLUSIONS: The efficacy of self-lowering of systolic blood pressure in mild hypertensives by continuous feedback was enhanced by 6 mmHg with 4 weeks of practice at home. Standard arm-cuff blood pressure was reduced by a clinically relevant amount. The home environment proved cost effective for this 'high-tech' approach.

Adult↗
PubMed1998

Effect of feedback signal and psychological characteristics on blood pressure self-manipulation capability.

Blood pressure presentation mode and personality are likely to influence biofeedback outcome. Thirty-six normotensive subjects were randomly assigned to visual or auditory continuous systolic feedback. "Distracting speech" and "broad band noise" were also superimposed and the effect on the biofeedback response was investigated. Psychological influence was also investigated. Systolic pressure reduction of 4 +/- 4.3 mmHg (visual, p = .04) and 5 +/- 5.5 mmHg (visual + auditory, p = .03) were achieved compared with auditory feedback (2 +/- 4.7 mmHg), which was less effective. The addition of noise or speech had no effect on the systolic response, but speech adversely affected diastolic reduction (p = .04). Mood (p = .003) was associated with systolic lowering, whereas increased trait anxiety (p = .06) and expectation (p = .03) had trends for opposite effects. Increased anger-hostility, state-anxiety, and expectation (p = .06) had links with systolic raising capability. We conclude that feedback modality and psychological characteristics have implications for studies investigating blood pressure manipulation capability.

Adult↗
PubMed1995

Physiological influences on continuous finger and simultaneous intra-arterial blood pressure.

Because of the clinical and experimental utility of continuous finger blood pressure measurements and the need for accuracy, we tested the performance of a new hydraulic device in 22 consecutive hypertensive subjects during physiological and pharmacological interventions. Ipsilateral brachial intra-arterial pressure was monitored during rest, Valsalva's maneuver, static handgrip, and mental arithmetic and after sublingual glyceryl trinitrate. In excess of 40,000 blood pressure values were analyzed. Average bias (intra-arterial minus finger blood pressure) was 8.2 +/- 17.0 mm Hg (mean +/- SD, P = NS) for systolic and 2.8 +/- 10.4 mm Hg (P = NS) for diastolic pressure. Two-way ANOVA of biases with subject and task factors showed a subject effect (P < .001). Intersubject and intrasubject standard deviations of bias were 13.8 and 9.8 mm Hg systolic and 8.7 and 5.7 diastolic, respectively. Linear drift (millimeters of mercury per minute) of finger pressure was greater (P < .001) for systolic than diastolic pressure during static exercise and math and after glyceryl trinitrate. Coefficients of determination for blood pressure ranged from 0.4 +/- 0.3 to 0.8 +/- 0.3 during the tasks. We conclude that (1) noninvasive finger blood pressure faithfully follows intra-arterial changes but with clinically relevant offsets, (2) this technique is best suited for assessing pressure changes, (3) physiological and pharmacological interventions do not consistently affect finger pressure accuracy, (4) many reports of finger blood pressure measuring devices are based on direct readings obtained with inadequate system response characteristics, and (5) the tested instrument falls short of the standard requirements (bias < or = 5 +/- 8 mm Hg) for devices that measure intermittently.

Aged↗
PubMed1991

Development of LYNX: a computer application for disease diagnosis and health monitoring in wild mammals, birds and reptiles.

IBM-compatible software has been developed so that quantitative and qualitative haematological and biochemical reference data for over 500 species of mammals, birds and reptiles can be made readily accessible to veterinary surgeons. The LYNX software makes it possible to retrieve these data at different taxonomic levels (species, genera, families, orders and classes) and to select data by age and sex. The data for each variable may be presented in the form of a reference range or as a frequency histogram. Notes describing the variations in blood cell morphology observed in healthy individuals of each species are included in the database. The user's own haematological and biochemical data can also be entered, stored and used.

Animals↗
PubMed1991

Erythrocyte size, number and haemoglobin content in vertebrates.

Relationships between erythrocyte number, size and haemoglobin content were examined in 441 species (101 families) of mammals, birds and reptiles. Whereas the total number of red cells (RBC), the mean cell volume (MCV) and mean cell haemoglobin (MCH) showed much variation, the haemoglobin level (Hb), packed cell volume (PCV) and mean cell haemoglobin concentration (MCHC) were relatively constant in all adult mammals and birds but lower in reptiles. There was a strong positive correlation between MCV and MCH and a strong negative correlation between MCV and RBC across all species. Mammals had more, smaller erythrocytes per unit volume of blood than birds, which, in their turn, had more, smaller erythrocytes than reptiles. The findings confirm that the oxygen-carrying capacity of the blood is highly conserved in birds and mammals but is lower in exothermic groups such as reptiles. Although the significance of the observed species differences in RBC and MCV has yet to be explained, the findings have considerable evolutionary, physiological and diagnostic interest.

Animals↗
PubMed1990

Haematology of clinically normal and sick captive reindeer (Rangifer tarandus).

A retrospective analysis of haematological values from clinically normal captive reindeer (Rangifer tarandus) showed that the red cell count, haemoglobin level, packed cell volume and lymphocyte count were higher and the erythrocyte sedimentation rate and eosinophil count were lower in juveniles than in adults. Newborn animals were anaemic compared with juveniles and adults and had high reticulocyte counts. The values from healthy reindeer were used to identify abnormal haematological variations in a number of sick animals. It was shown that reindeer exhibit similar haemopathological responses to those of other artiodactyla, with increases in the erythrocyte sedimentation rate and fibrinogen level being of particular diagnostic significance. Eosinophilia was the only abnormal haematological finding in individuals with subclinical infections of intestinal parasites.

Animals↗
PubMed1989

Age-related changes in the haematology of female F344 rats.

As little comprehensive baseline data are available on age-related haematological changes in genetically-defined rat strains, the haematology of female F344 rats is described in animals sampled at 2, 4, 8, 20, 66 and 121 weeks of age. Values for Hb, RBC and PCV increased from 2 weeks of age to reach adult levels at 8 weeks, whereas MCV, MCH and reticulocyte counts were high initially but decreased to reach the adult range at 8 weeks. Between 66 and 121 weeks, reticulocyte counts were significantly increased and values for MCHC significantly decreased. Lymphocytes were the predominant white cell type in each age group. The absolute numbers of neutrophils and lymphocytes showed slight variations between 2 and 66 weeks and both cell types increased significantly between 66 and 121 weeks. Platelet counts showed no overall age-related trends. Fibrinogen values increased from 2 weeks of age to reach the adult level at 8 weeks. One animal of the 14 sampled at 121 weeks showed changes in the blood, liver and spleen consistent with a diagnosis of lymphoid leukaemia.

Aging↗
PubMed1987

Fibrinogen levels in mammals suffering from bacterial infections.

In a retrospective survey of fibrinogen levels and neutrophil counts in 388 blood samples from mammals suffering from bacterial infection, the combined results of the two tests provided positive confirmation of infection in a greater percentage of samples than did the results of either test alone. In Perissodactyla, Artiodactyla and Proboscidea, the fibrinogen level was abnormal more often than the neutrophil count. It was concluded that a fibrinogen estimation is a valuable addition to routine haematological screening procedures in mammals.

Animals↗
PubMed1986

Haematological reference values for adult pumas, lions, tigers, leopards, jaguars and cheetahs.

Normal haematological values and fibrinogen levels were obtained from a number of healthy adult Felidae in the collection of the Zoological Society of London. The group comprised 29 pumas (Felis concolor), 32 lions (Panthera leo), 27 tigers (P tigris), 19 leopards (P pardus), 18 jaguars (P onca) and 22 cheetahs (Acinonyx jubatus). The values provided a basis for identifying abnormalities in the blood of sick individuals of these species and for undertaking interspecies comparisons.

Acinonyx↗
PubMed1985

Normal haematological values of axis deer (Axis axis), Père David's deer (Elaphurus davidianus) and barasingha (Cervus duvauceli).

Full blood counts and fibrinogen estimations were carried out on a number of clinically normal adult axis deer (Axis axis), Père David's deer (Elaphus davidianus) and barasingha (Cervus duvauceli). Apart from the finding of higher total red cell counts and a lower mean red cell volume in axis deer than in Père David's deer and barasingha, there was little interspecies variation. Some individual Père David's deer showed eosinophilia, thought to be associated with subclinical intestinal nematode infestation. The findings should provide a useful reference base for monitoring health in these species.

Animals↗
PubMed1984

Principal components analysis of haematological data from F344 rats with bladder cancer fed N-(ethyl)-all-trans-retinamide.

Several multivariate statistical methods are available which can alleviate the problems of analysing the large volumes of data generated from toxicological experiments. One such technique, principal components analysis, provides a method for exploring the relationships between a number of variables (such as blood parameters) and for eliminating redundant data if strong correlations exist between the characters. It also provides a method for clustering individuals, which may reveal similarities between animals in a treatment group or highlight individual 'outliers'. The application of principal components analysis to a set of haematological data from a trial evaluating the efficacy of a synthetic retinoid against carcinogen-induced bladder cancer in the rat has clearly shown, in two bivariate plots, that while some animals in the carcinogen-treated groups were normal, others were anaemic and that animals fed the synthetic retinoid and killed at 1 year had a microcytic anaemia. A full exploration of the data using conventional univariate statistical analysis would have involved at least 28 graphic representations of the data, as well as the interpretation of more than 130 means and SDs. Principal components analysis provides a valuable additional tool for the statistical analysis and exploration of toxicological data, but it must be used in conjunction with univariate or other multivariate methods if hypothesis testing is required. The use of multivariate techniques in toxicology may best be assessed by their practical application to toxicological data, and this paper presents such an evaluation with the aim of encouraging further exploration of the usefulness of principal components analysis. The raw data on which most analyses have been carried out are given.

Analysis of Variance↗
PubMed1984

Haematological values in mouflon (Ovis musimon): influence of age, sex, season and vitamin E status.

Full blood counts, fibrinogen estimations and red cell osmotic fragility tests were carried out on a number of clinically normal captive mouflon (Ovis musimon) from various locations. Age related differences in red and white cell counts and sex related differences in red cell counts were demonstrated. There was also evidence for seasonal changes in red cell values in adult females. During this study, some mouflon were found to be deficient in vitamin E and were transferred to a vitamin E supplemented diet. Comparison of findings on vitamin E deficient and supplemented animals revealed no significant haematological differences.

Age Factors↗
PubMed1983

Age related haematological changes in captive Barbary sheep (Ammotragus lervia).

Full blood counts were carried out on a number of clinically normal newborn, juvenile and adult Barbary sheep. Significant age related differences in the number and size of the red cells and in the absolute and relative numbers of neutrophils and lymphocytes were found. Fibrinogen levels and platelet counts were lowest in newborn animals. These differences could complicate the interpretation of haematological findings on sick Barbary sheep if not taken into account.

Age Factors↗
PubMed1983

Normal and clinical haematology in the yak (Bos grunniens).

Haematological examinations have been carried out on 21 clinically normal male and female adult yaks (Bos grunniens). Animals sedated with xylazine had significantly lower red cell counts, haemoglobin levels and packed cell volumes, fewer lymphocytes and higher monocyte counts than those bled while manually restrained. There were few significant sex differences. Several animals had eosinophilia associated with asymptomatic intestinal nematode infection. Haematological reference values were calculated for clinically normal, xylazine sedated and manually restrained yaks. These were used to identify haematological changes in 10 animals with various abnormal clinical signs. It was concluded that blood counts can provide valuable diagnostic information in this species.

Animals↗
PubMed1982

Haematological findings in healthy and sick African grey parrots (Psittacus erithacus).

Full blood counts and fibrinogen estimations were carried out on 11 clinically normal, adult African grey parrots. Reference values derived from these tests were used to identify abnormalities in the blood counts of 11 sick parrots thought to be suffering from bacterial infections. All sick birds showed higher than normal heterophil counts, paralleled in some cases by lymphocytosis, monocytosis, thrombocytosis and increased fibrinogen levels. Anaemia was present in two birds and several others showed minor red cell abnormalities. The findings indicate that clinical haematology can make a useful contribution to the differential diagnosis of infection in African grey parrots. The findings also suggest that the development of anaemia can be a significant complicating factor in infectious conditions in these birds.

Animals↗
PubMed1982

Haematological findings in red-necked wallabies (Protemnodon rufogrisea) with necrobacillosis.

Results of blood counts on 17 red-necked wallabies (Protemnodon rufogrisea) with confirmed necrobacillosis have been compared with those of 36 clinically normal animals. The most common abnormality in infected animals was a raised fibrinogen level, found in all of the cases tested. Neutrophilia occurred in 10 individuals and neutrophil morphology was abnormal in 15. Some infected animals showed monocytosis, raised erythrocyte sedimentation rates, high platelet counts and changes in their red cells. The findings provide useful information about the response of the blood to severe bacterial infections in red-necked wallabies and demonstrate the potential diagnostic use of clinical haematology in this species.

Animals↗
PubMed1981

Novel patterns of ultraviolet mutagenesis and Weigle reactivation in Staphylococcus aureus and phage phi 11.

The effects of u.v. irradiation on the survival of Staphylococcus aureus and its phage phi 11 were studied. The recA and uvr mutations affected their survival in a similar way to synonymous mutations in Escherichia coli. Weigle reactivation (W-reactivation) of phi 11 occurred in wild-type S. aureus and in a uvr mutant but to a lesser extent than has been found for phage lambda in E. coli. Reactivation was recA-dependent and was accompanied by u.v.-induced mutagenesis in a temperature-sensitive mutant of phi 11. Bacterial mutation to streptomycin resistance was induced by u.v. and was also recA-dependent. In S. aureus, as in E. coli, u.v. was a more effective mutagen in the uvr genetic background. However, a dose-squared response for u.v.-induced mutation of wild-type and uvr strains of S. aureus to streptomycin resistance, and of a trp auxotroph to tryptophan independence, was found only with u.v. doses below 1 J m-2. We suggest that, in relation to the Uvr mechanism of DNA repair, u.v. mutagenesis in S. aureus involves both repairable and non-repairable lesions. As in E. coli, the uvr genetic background reduced the u.v. dose required for maximal W-reactivation of u.v.-irradiated phage. However, there was no enhancement of W-reactivation by post-irradiation broth incubation of S. aureus. Our results are compatible with a non-inducible mechanism for this phenomenon.

DNA Repair↗