Biomedical subjects
R Freeman
Publications and source records attributed to R Freeman.
Pyrolysis mass spectrometry analysis of free-living and symbiotic cyanobacteria.
The potential of pyrolysis mass spectrometry to distinguish closely related cyanobacterial strains was assessed by using the technique to compare symbiotic cyanobacteria isolated from the hornwort Phaeoceros laevis and free-living cyanobacterial strains at the same field site. The same strains had previously been compared using polymerase chain reaction-based DNA fingerprinting techniques (West & Adams 1997, Appl. Environ. Microbiol. 63: 4479-4484). Many of the strains were grouped identically by the two techniques, although there were some differences, possibly resulting from the ability of these cyanobacteria to develop a range of specialised cell types having different chemical compositions to the vegetative cells. Although growth conditions were chosen to suppress cellular differentiation, this may not always have been completely successful. With careful control of growth conditions pyrolysis mass spectrometry has considerable potential as an additional tool for the phenetic comparison of cyanobacterial strains. It has the advantage that analysis is directly derived from whole cells, and hence is simpler and cheaper than DNA-based methods, although it does require the growth of axenic strains. The technique may be particularly useful in the study of some of the more cryptic unicellular and non-heterocystous filamentous cyanobacterial groups, in which the lack of cellular differentiation should minimise any variability in the chemical composition of cells.
Rapid detection of methicillin-resistant staphylococci by multiplex PCR.
A multiplex PCR was developed to detect the coagulase gene (coa; pathognomic of Staphylococcus aureus) and the mecA gene (characteristically encoding for methicillin resistance in staphylococci) in a single, rapid test. Suitable primers for the gene targets and an internal, amplification control were incorporated into a multiplex PCR assay, which was then optimized on a capillary air thermal cycler to improve the turnaround time of the test to approximately 1.5 hours. The assay was evaluated with 111 fresh clinical isolates of staphylococci. The multiplex PCR correctly distinguished between isolates of S. aureus, which were sensitive to methicillin (MSSA) and those resistant to it (MRSA). It also correctly differentiated between similar isolates of coagulase negative staphylococci (MSSE and MRSE respectively). It was concluded that this multiplex PCR was a rapid and reliable method for the detection of methicillin-resistant staphylococci.
No effect of adjunctive fluoxetine on eating behavior or weight phobia during the inpatient treatment of anorexia nervosa: an historical case-control study.
A six-week open label clinical trial investigated the response to fluoxetine in adolescents hospitalized for treatment of anorexia nervosa. Patients were drawn from consecutive admissions to a specialty treatment service and received fluxoetine as an add-on to their multidisciplinary treatment regimen beginning three weeks to one month postintake. Global clinical severity ratings of eating behavior and weight phobia were obtained at baseline and then at biweekly intervals. These ratings were compared to those obtained from matched historical case-controls who received an identical course of inpatient therapy but without adjunctive pharmacotherapy. Analyses failed to show any beneficial or detrimental effect of fluoxetine on these clinical measures. We conclude that fluoxetine has no robust additive or synergistic therapeutic benefit when measured against the effects of intensive, multidisciplinary inpatient therapy.
The importance of orthostatic intolerance in the chronic fatigue syndrome.
Chronic fatigue syndrome (CFS) or myalgic encephalomyelitis is a clinically defined syndrome characterized by persistent or relapsing debilitating fatigue for longer than 6 months in the absence of any definable medical diagnosis. The cause of this syndrome is unknown. Symptoms of orthostatic intolerance, such as disabling fatigue, dizziness, diminished concentration, tremulousness, and nausea, are often found in patients with CFS. In this review, we critically evaluate the relationship between orthostatic intolerance and CFS. Particular emphasis is placed on clinical diagnosis, laboratory testing, pathophysiology, and therapeutic management. It is hoped that this review will provide a stimulus for further study of this complex and disabling condition.
OSCE performance evaluations made by standardized patients: comparing checklist and global rating scores.
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Assessing the generalizability of OSCE measures across content domains.
PURPOSE: To assess the degree to which OSCE measures generalize across multiple administrations to the same students. METHODS: Students' scores from three OSCEs at one institution were correlated to determine the generalizability of the scoring systems across course domains. RESULTS: Analysis revealed that while checklist scores showed quite low correlations across examinations from different domains (ranging from 0.14 to 0.25), global process scores showed quite reasonable correlations (ranging from 0.30 to 0.44), with the correlations for global scores being significantly higher than those for checklist scores in all three comparisons. CONCLUSION: These data would seem to confirm the intuitions about each of these measures: the checklist scores are highly content-specific, while the global scores are evaluating a more broadly based set of skills. Implications for the use of these scales are discussed.
Rapid PCR-based detection of Streptococcus pneumoniae DNA in cerebrospinal fluid.
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ABC medium, a new chromogenic agar for selective isolation of Salmonella spp.
We describe a new chromogenic agar medium, ABC medium (alphabeta-chromogenic medium), which includes two substrates, 3, 4-cyclohexenoesculetin-beta-D-galactoside and 5-bromo-4-chloro-3-indolyl-alpha-D-galactopyranoside, to facilitate the selective isolation of Salmonella spp. This medium exploits the fact that Salmonella spp. may be distinguished from other members of the family Enterobacteriaceae by the presence of alpha-galactosidase activity in the absence of beta-galactosidase activity. A total of 1, 022 strains of Salmonella spp. and 300 other gram-negative strains were inoculated onto this medium. Of these, 1,019 (99.7%) strains of Salmonella spp. produced a characteristic green colony, whereas only 1 strain (0.33%) of non-Salmonella produced a green colony. A total of 283 stool samples were cultured onto desoxycholate citrate (DC) agar and ABC medium by direct inoculation and after selective enrichment in selenite broth. Overall, the sensitivity and specificity were superior for ABC medium (100 and 90.5%, respectively) than for DC agar (88 and 26.9%, respectively). We conclude that ABC medium offers a high degree of specificity for the detection of Salmonella spp. in stool samples.
Rapid immunochromatographic assay for diagnosis of tuberculosis: antibodies detected may not be specific.
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System identification of closed-loop cardiovascular control mechanisms: diabetic autonomic neuropathy.
We applied cardiovascular system identification (CSI) to characterize closed-loop cardiovascular regulation in patients with diabetic autonomic neuropathy (DAN). The CSI method quantitatively analyzes beat-to-beat fluctuations in noninvasively measured heart rate, arterial blood pressure (ABP), and instantaneous lung volume (ILV) to characterize four physiological coupling mechanisms, two of which are autonomically mediated (the heart rate baroreflex and the coupling of respiration, measured in terms of ILV, to heart rate) and two of which are mechanically mediated (the coupling of ventricular contraction to the generation of the ABP wavelet and the coupling of respiration to ABP). We studied 37 control and 60 diabetic subjects who were classified as having minimal, moderate, or severe DAN on the basis of standard autonomic tests. The autonomically mediated couplings progressively decreased with increasing severity of DAN, whereas the mechanically mediated couplings were essentially unchanged. CSI identified differences between the minimal DAN and control groups, which were indistinguishable based on the standard autonomic tests. CSI may provide a powerful tool for assessing DAN.
Human studies of recombinant human nerve growth factor and diabetic peripheral neuropathy.
Recombinant human nerve growth factor (rhNGF) is the first neurotrophin to be investigated in clinical trials of diabetic peripheral neuropathy (DPN). To date, the drug has been administered to 60 healthy volunteers and 209 patients with DPN in phase I and II studies. Results from phase I have demonstrated rhNGF to be safe and generally well tolerated in doses up to 1.0 microg/kg given intravenously or subcutaneously for up to 12 doses. Doses investigated in phase II were 0.1 or 0.3 microg/kg s.c. 3 days a week for 6 months. Preliminary results from this trial suggest that rhNGF specifically improves the function of small-fibre sensory peripheral neurons, which is consistent with its postulated mode of action. Two pivotal 12-month phase III trials are underway in diabetic patients with symptomatic peripheral neuropathy to confirm the therapeutic effects of rhNGF. Results from these trials are expected in 2000.
The pharmacotherapy of depressive illness in adolescents: an open-label comparison of fluoxetine with imipramine-treated historical controls.
BACKGROUND: This open-label, 6-week clinical trial investigated the response to fluoxetine in medication-naive adolescents hospitalized for treatment of major depression. METHOD: A total of 52 consecutively admitted patients (mean age = 15.7 years) fulfilling Research Diagnostic Criteria for unipolar, nonpsychotic major depression received fluoxetine monotherapy (mean dose = 33.2 mg/day) in conjunction with psychosocial therapies. Outcome was assessed weekly using the Hamilton Rating Scale for Depression (HAM-D) and the Clinical Global Impressions Scale (CGI). Response in this cohort was compared with that observed in 28 historical controls treated with imipramine (mean dose = 217 mg/day) who were consecutively admitted patients to this same facility and assessed in an identical, standardized, open-label protocol. RESULTS: HAM-D scores decreased by a mean of 13.2 in the fluoxetine group compared with 10.2 in the group receiving imipramine (p<.002). The mean percentage decreases in HAM-D scores in the 2 groups were 54.3% and 41.4%, respectively (p<.003). The percentages of patients classified as responders based on a final CGI score of 2 or less were 48.1% and 17.9%, respectively (p = .009). Medications were generally well tolerated with only 5 patients failing to complete the full 6 weeks of their original treatment. CONCLUSION: In spite of the uncontrolled nature of these data, the findings add to recent evidence suggesting more favorable response to selective serotonin reuptake inhibitors than tricyclics in adolescents with depressive illness.
Rapid identification of Mycobacterium bovis BCG by the detection of the RD1 deletion using a multiplex PCR technique.
The BCG vaccine strain cannot, with confidence, be differentiated from other members of the Mycobacterium tuberculosis complex on phenotypic tests alone. Isolates from clinical sites not associated with vaccination may be confused with M. tuberculosis. A characteristic of BCG strains is the deletion of the genomic region RD1; detection of this forms the basis of a multiplex polymerase chain reaction (PCR) assay to distinguish BCG strains. In this study, 28 M. tuberculosis complex strains were analysed by the PCR assay. A DNA sequence displaying the characteristic deletion was detected in all eleven of the BCG strains tested and was not found in representatives of other members of the complex, including M. bovis. Thus, the assay affords a rapid, simple and effective method for the discrimination of the BCG vaccine strain from other members of the M. tuberculosis complex.
Significance of cytomegalovirus for long-term survival after orthotopic liver transplantation: a prospective derivation and validation cohort analysis.
BACKGROUND: Cytomegalovirus (CMV) infection and disease has been found to be associated with decreased graft and patient survival among heart transplant recipients. We sought to explore the effect of CMV infection and disease on long-term survival in orthotopic liver transplant (OLT) recipients using a derivation and validation cohort. METHODS: For derivation-validation modeling, we used data collected from two prospectively followed cohorts as the basis for multivariate analyses: 167 OLT recipients from the Boston Center for Liver Transplantation (the derivation set; median follow-up: 5.5 years, mortality: 40%) and an independent cohort of 294 OLT recipients from the Mayo Clinic (the validation set; median follow-up: 4.8 years, mortality: 27%). RESULTS: Underlying liver disease other than primary biliary cirrhosis or sclerosing cholangitis, number of units of red blood cells administered during transplantation, and donor CMV seropositivity were the pre- and intratransplant variables independently associated (P<0.01) with decreased long-term survival in the derivation cohort. For variables collected up to 1 year after transplantation, the need for retransplan. tation, CMV pneumonia, invasive fungal disease, and underlying liver disease other than primary biliary cirrhosis or sclerosing cholangitis were independently associated (P<0.01) with decreased long-term survival in the derivation cohort. The magnitude of the relationship of each pre-, intra-, and posttransplant factor with survival, as measured by the relative risk, did not significantly differ between the derivation and validation cohorts. The derivation model, incorporating pre-, intra-, and posttransplant factors, had receiver operating characteristic areas of 73% and 74% for 5-year mortality in the derivation and validation cohorts, respectively. CONCLUSIONS: Data from a derivation and an independent validation cohort demonstrate that CMV factors (reflected by either donor CMV seropositivity at transplantation, CMV pneumonia, or CMV disease within the first posttransplant year) are independently associated with decreased long-term survival in OLT recipients.
Assessing and managing dental phobia in general practice: some practical suggestions.
An awareness of the predisposing dynamics of dental phobia allows members of the dental team to deal empathetically and objectively with their child and adult patients' anxieties and concerns. The use of communication skills and behavioural management techniques together with or without conscious sedation, allow the patient to slowly progress from experiencing phobic reactions toward dental treatment to a lesser form of dental anxiety.
A psychodynamic theory for dental phobia.
Dentists recognise various degrees of dental anxiety in their patients. There are those who are relaxed, those who are anxious and those who are dentally phobic. The question remains why should disagreeable dental experiences result in dental anxiety in one patient, have little effect upon another and cause dental phobia in a third? The aim of this paper is to propose a psychodynamic theory for dental phobia based upon the ideas of false connections and displacement.
Automated Processing of Two-Dimensional Correlation Spectra
An automated scheme is described which locates the centers of cross peaks in two-dimensional correlation spectra, even under conditions of severe overlap. Double-quantum-filtered correlation (DQ-COSY) spectra have been investigated, but the method is also applicable to TOCSY and NOESY spectra. The search criterion is the intrinsic symmetry (or antisymmetry) of cross-peak multiplets. An initial global search provides the preliminary information to build up a two-dimensional "chemical shift grid." All genuine cross peaks must be centered at intersections of this grid, a fact that reduces the extent of the subsequent search program enormously. The program recognizes cross peaks by examining the symmetry of signals in a test zone centered at a grid intersection. This "symmetry filter" employs a "lowest value algorithm" to discriminate against overlapping responses from adjacent multiplets. A progressive multiplet subtraction scheme provides further suppression of overlap effects. The processed two-dimensional correlation spectrum represents cross peaks as points at the chemical shift coordinates, with some indication of their relative intensities. Alternatively, the information is presented in the form of a correlation table. The authenticity of a given cross peak is judged by a set of "confidence criteria" expressed as numerical parameters. Experimental results are presented for the 400-MHz double-quantum-filtered COSY spectrum of 4-androsten-3,17-dione, a case where there is severe overlap. Copyright 1998 Academic Press.