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Biomedical subjects

R Freeman

Publications and source records attributed to R Freeman.

At least 37 records · Page 2Linked to original sources
PubMed1991

Spectral analysis of heart rate in diabetic autonomic neuropathy. A comparison with standard tests of autonomic function.

Power spectral analysis of the heart rate was compared with standard tests of autonomic function performed on 15 insulin-dependent diabetic patients with symptoms of autonomic dysfunction. The high-frequency power, low-frequency power, and total power of the heart rate power spectrum measured in the supine position--possible measures of parasympathetic nervous system function--were significant predictors of the expiratory-inspiratory ratio, the beat-to-beat heart rate difference on deep respiration, the standard deviation of the resting heart rate, the 30:15 ratio, and the Valsalva ratio. The change in low-frequency power on moving from the supine to upright position, a possible measure of sympathetic nervous system function, was a modest predictor of the systolic and diastolic blood pressure fall in response to postural change, but a poor predictor of the blood pressure response to isometric exercise and a cold stimulus. This study supports the role of heart rate power spectral analysis as a clinical test of autonomic function in patients with known or suspected autonomic failure.

Adult↗
PubMed1991

Delayed-focus pulses for magnetic resonance imaging: an evolutionary approach.

An evolutionary algorithm has been used to design a family of shaped radiofrequency pulses giving uniform absorption-mode excitation across a predetermined frequency band. By allowing a free precession interval before signal acquisition, time is left for field gradients to be switched and for undesirable transients to decay.

Electromagnetic Phenomena↗
PubMed1991

Differentiation between mycobacteria of the Mycobacterium tuberculosis complex by pyrolysis mass spectrometry.

32 isolates belonging to the Mycobacterium tuberculosis complex were examined by pyrolysis mass spectrometry (PyMS). This technique demonstrated that recent clinical isolates of M. africanum were indistinguishable from those of M. bovis and together formed a homogeneous group distinct from M. tuberculosis. Isolates of BCG were heterogeneous and more closely related to laboratory-adapted strains of M. tuberculosis than to recent isolates of either M. tuberculosis or M. bovis. PyMS is a simple and inexpensive technique which gives interesting information on the relationships between members of the M. tuberculosis complex and can make the clinically important distinction between strains of M. bovis and M. tuberculosis accurately and much more rapidly than conventional techniques.

Mass Spectrometry↗
PubMed1991

Predictors for infection following open-heart surgery.

A large open-heart surgery unit dealing with approximately 1000 elective patients per annum and housed in a dedicated suite, including a specialized intensive therapy unit, has provided a unique model for the study of predictors of infections and related phenomena. Over more than 10 years a series of studies has shown: the powerful effect of antibiotic usage on the colonization/infection rates with Gram-negative bacilli; the predictive relationships between preoperative chest status and the development of postoperative chest problems; an important correlation between preoperative peak urine flow rates and susceptibility to postoperative urinary tract infections; and the predictive significance of preoperative antibodies to enteric Gram-negative bacilli in relation to postoperative pyrexia and Gram-negative infection. The lessons learned from this easily studied group of patients may have important applications in other surgical settings.

Anti-Bacterial Agents↗
PubMed1991

Strain differentiation of nosocomial isolates of Pseudomonas aeruginosa by pyrolysis mass spectrometry.

Pyrolysis mass spectrometry (PyMS) was used for rapid interstrain comparison of Pseudomonas aeruginosa isolates from a small outbreak of sternal wound infections in a cardiothoracic surgical ward. The PyMS results were compared with those obtained by conventional O-serotyping. All the isolates were phage non-typable. Evidence obtained from PyMS of identity/non-identity between isolates correlated completely with that obtained by O-typing and correctly identified those isolates comprising the epidemic strain, in one instance in advance of O-serotyping. The speed and versatility of PyMS make it an attractive technique for the initial screening of isolates from nosocomial outbreaks of infection with P. aeruginosa and other organisms.

Bacterial Typing Techniques↗
PubMed1991

Inter-strain comparison by pyrolysis mass spectrometry in the investigation of Staphylococcus aureus nosocomial infection.

Pyrolysis mass spectrometry (PyMS) was used to examine isolates of Staphylococcus aureus from an outbreak of wound infections on a cardiothoracic surgical unit, some of which were thought to have been related to a point-source in the operating theatre. The PyMS results were compared with the results of phage typing. Both methods suggested that a single strain of S. aureus, of phage pattern 29/52/52A/79/80/81, was responsible for some of the wound infections, but PyMS also identified two patients with phage non-typable isolates. Phage typing indicated four staff members as possible carriers of the epidemic strain, but PyMS indicated only two. Epidemiological enquiry confirmed that one of the two members of staff identified by both methods was likely to have been the source of the theatre-based infection. PyMS is a rapid and relatively inexpensive technique for the investigation of nosocomial S. aureus infection and was more discriminatory than phage typing in this instance.

Carrier State↗
PubMed1991

Rapid inter-strain comparison by pyrolysis mass spectrometry in nosocomial infection with Xanthomonas maltophilia.

Seventeen strains of Xanthomonas maltophilia and one strain of Pseudomonas cepacia were examined by pyrolysis mass spectrometry (PYMS). The Xanthomonas strains comprised 11 clinical and environmental isolates from a suspected outbreak of colonization and infection on a heart-lung transplant intensive care unit, two strains from patients elsewhere in the same hospital and four strains from a national reference collection. The single isolate of Pseudomonas cepacia was from a sink in the same affected intensive care unit. A series of discriminant analyses performed on the PYMS-derived data showed that, whereas six strains of Xanthomonas from the respiratory tract, blood and ventilatory equipment of one of the affected patients were indistinguishable, all the other isolates were distinct. The results of PYMS rapid inter-strain comparison were in accord with those of an epidemiological investigation which suggested that the episode was due to unauthorized reuse of disposable nebulizers and not to cross-infection between patients. Pyrolysis mass spectrometry with rapid data analysis is a potentially useful technique for the investigation of nosocomial infections due to organisms such as X. maltophilia.

Bacteriological Techniques↗
PubMed1991

Discrepant results with a latex agglutination test in the assessment of cytomegalovirus antibody status of cardiac transplant donors.

The cytomegalovirus (CMV) antibody status of 79 cardiac transplant recipients and their respective donors was determined by a latex-agglutination technique and by a CMV IgG ELISA technique on the same samples. Although good agreement between the two methods was found in recipient samples the latex method produced significantly more positive results in donor samples than did the ELISA test. Clinical and serological follow-up of the patients concerned over the first 6 months after transplantation suggested that the ELISA results were correctly predictive of donor transmitted primary CMV infection and that, therefore, the latex test was producing false positive readings. Further investigation is needed to discover the reason for these discrepancies. The use of donor samples taken at the time of organ retrieval may have prejudiced the latex test results. Until these problems are resolved it is suggested that the latex agglutination technique should not be the sole method adopted to assess donor CMV antibody status.

Antibodies, Viral↗
PubMed1991

Rapid inter-strain comparison by pyrolysis mass spectrometry of coagulase-negative staphylococci from persistent CAPD peritonitis.

Pyrolysis mass spectrometry (PyMS) was used as a method of rapid inter-strain comparison of 19 isolates of coagulase-negative staphylococci from episodes of CAPD peritonitis. Thirteen isolates were from multiple, but distinct, episodes of peritonitis in 6 patients and the remaining 6 isolates were from 6 patients with single episodes. The results, expressed in terms of identity/non-identity of strains, were compared with those obtained using an established typing system comprising an extended antibiogram, determination of biotype and plasmid profile analysis. The PyMS results for inter-strain comparison were in agreement with the reference typing scheme results. PyMS can be used in this setting to rapidly obtain evidence that persistent infection is/is not likely to be due to the same organism, although it cannot be used for formal typing. The results by both methods showed that serial, apparently distinct, episodes of peritonitis over periods as long as 120 days may be due to the same strain of coagulase-negative staphylococcus. Clinically based distinctions between recurrence of infection (same strain) and re-infection (different strains) may not always be supported by the microbiological evidence.

Coagulase↗
PubMed1991

Incrimination of an environmental source of a case of Legionnaires' disease by pyrolysis mass spectrometry.

Following a case of Legionnaires' disease Legionella pneumophila of the same serogroup was isolated from the hot water system of the hotel which had been epidemiologically implicated as the source of the infection. Pyrolysis mass spectrometry (PyMS) was used to compare 11 isolates from the hotel water sample with the patient's strain. Epidemiologically unrelated isolates, both clinical and environmental, of the same serogroup and monoclonal antibody type of L. pneumophila were included in the same analysis, together with relevant reference strains. The patient strain was shown to be indistinguishable from seven of the hotel water isolates, but clearly different from other unrelated clinical isolates, the reference strains and some of the other environmental isolates. PyMS is a rapid and cheap method for inter-strain comparison for L. pneumophila.

Aged↗
PubMed1991

The treatment of orthostatic hypotension with dihydroxyphenylserine.

Neurogenic orthostatic hypotension is an incapacitating symptom of central and peripheral autonomic nervous system degeneration. It occurs in such clinical conditions as multiple system atrophy, pure autonomic failure, and small-fiber peripheral neuropathies. Although many treatments are available, their effects are inconsistent, unsustained, and complicated by side effects. 3,4-Dihydroxyphenylserine is a synthetic, unnatural amino acid that is an immediate norepinephrine precursor. There is theoretical and clinical evidence supporting the use of this agent in the treatment of neurogenic orthostatic hypotension in patients with peripheral and central autonomic nervous system dysfunction. We review the biochemistry, pharmacokinetics, and possible mechanisms of action and clinical utility of this agent in the treatment of neurogenic orthostatic hypotension.

Droxidopa↗
PubMed1991

Epidemiological typing of coagulase-negative staphylococci by pyrolysis mass spectrometry.

Pyrolysis mass spectrometry (PMS) was evaluated for the epidemiological typing of coagulase-negative staphylococci (CNS) in situations in which it was necessary to distinguish between repeated isolation of the same strain from a single patient (genuine infection) and coincidental isolation of unrelated strains (contamination). Thirteen CNS isolates were examined, consisting of five pairs, each pair isolated from a single patient, and three unrelated strains. PMS analysis gave results equivalent to a conventional typing system comprising antibiogram, biotype and plasmid profile analysis. Both methods facilitate differentiation between genuine infection with CNS and the isolation of contaminants. The speed, reproducibility, versatility and relatively low cost of PMS suggest that it may be a valuable new technique for the epidemiological typing of CNS in routine clinical settings.

Coagulase↗
PubMed1991

A comparative study of ethamsylate and mefenamic acid in dysfunctional uterine bleeding.

The effects of ethamsylate and mefenamic acid on menstrual blood loss were compared in a double-blind trial in 34 women with menorrhagia. Both drugs produced statistically significant reductions in blood loss during the 3 months of treatment; the overall reduction was 20% in the ethamsylate group and 24% in the mefenamic acid group. Compared with pretreatment values, blood loss was significantly less in each of the 3 treatment months in the mefenamic acid group, but only in the second and third months of treatment in the ethamsylate group. However, more women had a clinically useful reduction in blood loss (greater than 40%) in the ethamsylate group. The onset of effect of mefenamic acid was rapid but ethamsylate showed a comparatively greater effect as the trial progressed. Cessation of treatment was followed by an increase in blood loss, more pronounced in mefenamic acid group who reverted to pre-treatment levels. A greater number of side-effects were reported with mefenamic acid.

Adolescent↗
PubMed1991

An unusual case of pica.

This paper presents the case of a 29 year old woman who compulsively ate rocks and pebbles, a habit developed in childhood. Extensive psychometric testing did not demonstrate phobias, obsessions, tendency to increased anxiety, depression or anorexic or bulimic disorder. The development of pica is partially explained by a childhood eating disorder, obsessive personality traits, cultural factors and specific (personality induced) stresses. Stress-reducing measures were successful in eliminating the eating disorder.

Adult↗
PubMed1991

The prediction of dentists' work behaviour; factors affecting choice or intention in the treatment of special need patients.

The present study was undertaken as part of an overall strategy to develop a co-ordinated dental health care programme for special need patients between general dental practitioners and the community dental service. The beliefs, attitudes and work behaviours of the practitioners were examined, using the theory of reasoned action, in order to highlight perceived difficulties associated with treating this particular patient group as well as to find those dentists willing to treat and carry out domiciliary dental care for them. The results demonstrated that those dentists who had previous experience of treating special need patients and carrying out a variety of domiciliary dental treatments intended to provide dental care for this group. Furthermore, the dentists differed in their evaluations with regard to beliefs and attitude. Those dentists who intended to provide dental care appeared to have more positive attitudes and were able to assess and perceive the relevance as well as the reality of their own beliefs in the light of their previous working behaviours.

Adult↗