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Biomedical subjects

M M Cohen

Publications and source records attributed to M M Cohen.

At least 37 records · Page 2Linked to original sources
PubMed2001

The validity of performance assessments using simulation.

BACKGROUND: The authors wished to determine whether a simulator-based evaluation technique assessing clinical performance could demonstrate construct validity and determine the subjects' perception of realism of the evaluation process. METHODS: Research ethics board approval and informed consent were obtained. Subjects were 33 university-based anesthesiologists, 46 community-based anesthesiologists, 23 final-year anesthesiology residents, and 37 final-year medical students. The simulation involved patient evaluation, induction, and maintenance of anesthesia. Each problem was scored as follows: no response to the problem, score = 0; compensating intervention, score = 1; and corrective treatment, score = 2. Examples of problems included atelectasis, coronary ischemia, and hypothermia. After the simulation, participants rated the realism of their experience on a 10-point visual analog scale (VAS). RESULTS: After testing for internal consistency, a seven-item scenario remained. The mean proportion scoring correct answers (out of 7) for each group was as follows: university-based anesthesiologists = 0.53, community-based anesthesiologists = 0.38, residents = 0.54, and medical students = 0.15. The overall group differences were significant (P < 0.0001). The overall realism VAS score was 7.8. There was no relation between the simulator score and the realism VAS (R = -0.07, P = 0.41). CONCLUSIONS: The simulation-based evaluation method was able to discriminate between practice categories, demonstrating construct validity. Subjects rated the realism of the test scenario highly, suggesting that familiarity or comfort with the simulation environment had little or no effect on performance.

Aged↗
PubMed2001

Enhancement of contrast echocardiography by image variability analysis.

BACKGROUND: Although there have been recent advances in echocardiography, many studies remain suboptimal due to poor image quality and unclear blood-myocardium border. We developed a novel image processing technique, cardiac variability imaging (CVI), based on the variance of pixel intensity values during passage of ultrasound microbubble contrast into the left ventricle chamber, with the aim of enhancing endocardial border delineation and image quality. METHODS AND RESULTS: CVI analysis was performed on simulated data to test and verify the mechanism of image enhancement. Then CVI analysis was applied to echocardiographic images obtained in two different clinical studies, and still images were interpreted by expert reviewers. In the first study (N = 15), using contrast agent EchoGen, the number of observable wall segments in end-diastolic images, for example, was significantly increased by CVI (4.93) as compared to precontrast (3.28) and contrast images (3.36), P < 0.001 for both comparisons to CVI. In the second study (N = 8), using contrast agent Optison, interobserver variability of manually traced end-diastolic volumes was significantly decreased using CVI (22.3 ml) as compared to precontrast (63.4) and contrast images (49.0), P < 0.01 for both comparisons to CVI. CONCLUSION: CVI can substantially enhance endocardial border delineation and improve echocardiographic image quality and image interpretation.

Algorithms↗
PubMed2001

Bayes factor of model selection validates FLMP.

The fuzzy logical model of perception (FLMP; Massaro, 1998) has been extremely successful at describing performance across a wide range of ecological domains as well as for a broad spectrum of individuals. An important issue is whether this descriptive ability is theoretically informative or whether it simply reflects the model's ability to describe a wider range of possible outcomes. Previous tests and contrasts of this model with others have been adjudicated on the basis of both a root mean square deviation (RMSD) for goodness-of-fit and an observed RMSD relative to a benchmark RMSD if the model was indeed correct. We extend the model evaluation by another technique called Bayes factor (Kass & Raftery, 1995; Myung & Pitt, 1997). The FLMP maintains its significant descriptive advantage with this new criterion. In a series of simulations, the RMSD also accurately recovers the correct model under actual experimental conditions. When additional variability was added to the results, the models continued to be recoverable. In addition to its descriptive accuracy, RMSD should not be ignored in model testing because it can be justified theoretically and provides a direct and meaningful index of goodness-of-fit. We also make the case for the necessity of free parameters in model testing. Finally, using Newton's law of universal gravitation as an analogy, we argue that it might not be valid to expect a model's fit to be invariant across the whole range of possible parameter values for the model. We advocate that model selection should be analogous to perceptual judgment, which is characterized by the optimal use of multiple sources of information (e.g., the FLMP). Conclusions about models should be based on several selection criteria.

Bayes Theorem↗
PubMed2001

Effects of gravitational and optical stimulation on the perception of target elevation.

To examine the combined effects of gravitational and optical stimulation on perceived target elevation, we independently altered gravitational-inertial force and both the orientation and the structure of a background visual array. While being exposed to 1.0, 1.5, or 2.0 Gz in the human centrifuge at NASA Ames Research Center, observers attempted to set a target to the apparent horizon. The target was viewed against the far wall of a box that was pitched at various angles. The box was brightly illuminated, had only its interior edges dimly illuminated, or was kept dark. Observers lowered their target settings as Gz was increased; this effect was weakened when the box was illuminated. Also, when the box was visible, settings were displaced in the same direction as that in which the box was pitched. We attribute our results to the combined influence of otolith-oculomotor mechanisms that underlie the elevator illusion and visual-oculomotor mechanisms (optostatic responses) that underlie the perceptual effects of viewing pitched visual arrays.

Adult↗
PubMed2001

Osteomyelitis in the diabetic patient: diagnosis and treatment. Part 1: Overview, diagnosis, and microbiology.

Foot ulcerations are common among people with diabetes and often lead to mixed infections that require hospitalization and create significant challenges for clinicians. Many result in contiguous bone infections. Regimens used to treat osteomyelitis often are seen as controversial. A subtle balance between medical and surgical therapy is necessary if a potentially curative outcome is to be achieved. The following article is one of a two-part series. This, the first manuscript, discusses the diagnosis and microbiology of contiguous osteomyelitis in the diabetic foot.

Diabetic Foot↗
PubMed2001

Osteomyelitis in the diabetic patient: diagnosis and treatment. Part 2: Medical, surgical, and alternative treatments.

In the diabetic population, wound and foot infections are often mixed, containing from three to six organisms. This creates a significant problem regarding antibiotic protocols. Many of these episodes result in contiguous bone infections with subsequent erosive changes, sequestra, and involucrum. A multidisciplinary approach to treatment is often required. Studies have shown that a protocol of 6 weeks of intravenous antibiotics may be appropriate to treat osteomyelitis; however, this is controversial and often not curative. Osteomyelitis is a surgical disease; a subtle balance between medical and surgical therapy is necessary if a potentially curative outcome is to be achieved. The duration of antibiotic therapy may be shortened considerably after surgical intervention. In cases of infection mitigated by severe peripheral vascular disease, end-stage renal disease, diabetes, or other medical problems where surgery is not an option, long-term antibiotics may be used as suppressive therapy along with adjunctive local treatments. The following is the second article of a two-part series. The first paper discussed the diagnosis and microbiology of contiguous osteomyelitis in the diabetic foot. This article outlines the various medical, antibiotic, and surgical options available to the clinician. Adjunctive and alternative therapies also are discussed.

Amputation, Surgical↗
PubMed2000

Multiple meningiomas, craniofacial hyperostosis and retinal abnormalities in Proteus syndrome.

Because clinical evidence suggests that Proteus syndrome may be caused by a somatic mutation during early development, resulting in mosaicism, the possible types of abnormalities and their clinical distributions are highly variable. Here, we report on an unusual patient with Proteus syndrome. Manifestations included multiple meningiomas, polymicrogyria, and periventricular heterotopias. Both eyes had epibulbar cystic lesions. The retina showed diffuse disorganization with nodular gliosis, retinal pigmentary abnormalities, chronic papilledema, and optic atrophy. Other abnormalities included progressive cranial, mandibular, maxillary, and auditory canal hyperostoses, epidermal nevi, and mental deficiency. The limbs were proportionate, and the hands and feet were normal.

Adult↗
PubMed2000

Fronto-ocular syndrome: newly recognized trigonocephaly syndrome.

We describe an apparently unique disorder, Fronto-Ocular syndrome, present in a mother and her two daughters, and comprising trigonocephaly due to coronal and metopic craniosynostosis, ocular hypotelorism, ocular proptosis and ptosis, epicanthal folds, hypoplastic supraorbital ridges, elevated nasal bridge, thin philtrum, high-arched palate and a narrow bifrontal region. Both daughters have glabellar capillary hemangiomas, a congenital heart defect and mild developmental disabilities. Review of the literature failed to disclose any syndrome with similar findings. It is likely that this disorder represents an autosomal dominant condition, that arose as a new mutation in the mother. Mutational analysis of fibroblast growth factor receptor (FGFR) 1 and FGFR2 failed to identify the molecular basis of the disorder.

Adult↗
PubMed2000

Ocular manifestations in Proteus syndrome.

We report on the ocular manifestations of a Proteus syndrome patient. Several of the manifestations are due to severe maldevelopment and malfunction of the neuroretina including strabismus, nystagmus, high myopia, and retinal pigmentary abnormalities. In reviewing the literature, strabismus and epibulbar tumors were recorded most commonly. Some articles about presumed Proteus syndrome are spurious; these have not been included here. Also, because of anecdotal and nonsystematic study of the eye and because of the ascertainment bias inherent in literature reports, numbers of cases of each ocular manifestation have not been tabulated.

Child, Preschool↗
PubMed2000

Complementary therapies: have they become accepted in general practice?

OBJECTIVES: To describe Victorian general practitioners' attitudes towards and use of a range of complementary therapies. DESIGN: A self-administered postal survey sent to a random sample of 800 general practitioners (GPs) in Victoria in July 1997. PARTICIPANTS: 488 GPs (response rate, 64%). MAIN OUTCOME MEASURES: GPs' knowledge; opinions about harmfulness and effectiveness; appropriateness for GPs to practise; perceived patient demand; need for undergraduate education; referral rates to complementary practitioners; and training in and practice of each therapy. RESULTS: Acupuncture, hypnosis and meditation are well accepted by the surveyed GPs, as over 80% have referred patients patients to practitioners of these therapies and nearly half have considered using them. General practitioners have trained in various therapies--meditation (34%), acupuncture (23%), vitamin and mineral therapy (23%), hypnosis (20%), herbal medicine (12%), chiropractic (8%), naturopathy (6%), homoeopathy (5%), spiritual healing (5%), osteopathy (4%), aroma-therapy (4%), and reflexology (2%). A quarter to a third were interested in training in chiropractic, herbal medicine, naturopathy and vitamin and mineral therapy. General practitioners appear to underestimate their patients' use of complementary therapies. CONCLUSIONS: There is evidence in Australia of widespread acceptance of acupuncture, meditation, hypnosis and chiropractic by GPs and lesser acceptance of the other therapies. These findings generate an urgent need for evidence of these therapies' effectiveness.

Acupuncture Therapy↗
PubMed2000

Genetic approaches to understanding brain development: holoprosencephaly as a model.

Holoprosencephaly (HPE) is the most common major developmental defect of the forebrain in humans. Clinical expression is variable, ranging from a small brain with a single cerebral ventricle and cyclopia to clinically unaffected carriers in familial HPE. Significant etiologic heterogeneity exists in HPE and includes both genetic and environmental causes. Defects in the cell signaling pathway involving the Sonic Hedgehog (SHH) gene, as well as defects in the cholesterol biosynthesis have been shown to cause HPE in humans. More recently, HPE genes from additional signaling pathways have been identified. These discoveries and current genetic approaches serve as a paradigm for studying normal and abnormal brain morphogenesis. MRDD Research Reviews 6:15-21, 2000.

Brain↗
PubMed2000

Predicting difficult intubation: a multivariable analysis.

PURPOSE: To develop a clinically useful and valid model for predicting difficult laryngoscopic tracheal intubation in patients with seemingly normal airways by adhering to the principles of multivariable model development. METHODS: This was an observational study performed at a tertiary-care teaching hospital. Preoperatively, 444 randomly selected patients requiring tracheal intubation for elective surgery were assessed. In addition, 27 patients in whom tracheal intubation was difficult, but were not assessed preoperatively, were assessed postoperatively. One assessor, blinded to the intubation information, collected the predictor variables. A reliable definition for difficult intubation was used and all attempts were made to eliminate sources of bias. Multivariable modeling was performed using logistic regression and the model was validated using the bootstrapping technique. RESULTS: Of the 461 patients included in the analysis, 38 were classified as difficult to intubate. Multivariable analysis identified three airway tests that were highly significant for predicting difficult tracheal intubation. These were: 1) "mouth opening", 2) "chin protrusion", and 3) "atlanto-occipital extension". Using these tests, a validated, highly reliable and predictive model is produced to determine the probability of difficult intubation for patients. At a selected probability cut-off value, the model is 86.8% sensitive and 96.0% specific. CONCLUSION: A simple and accurate multivariable model, consisting of three airway tests, is produced for predicting difficult laryngoscopic tracheal intubation. Additional studies will be required to determine the accuracy and feasibility of this model when applied to a large sample of new patients by multiple anesthesiologists.

Adult↗
PubMed2000

Tests of auditory-visual integration efficiency within the framework of the fuzzy logical model of perception.

The fuzzy logical model of perception [FLMP, Massaro, Perceiving Talking Faces: From Speech Perception to a Behavioral Principle (MIT Press, Cambridge, MA, 1998)] has been extremely successful at describing performance across a wide range of ecological domains as well as for a broad spectrum of individuals. Because the model predicts optimal or maximally efficient integration, an important issue is whether this is the case for most individuals. Three databases are evaluated to determine to what extent a significant quantitative improvement in predictive ability can be obtained if integration is assumed to be somewhat inefficient. For the most part, there were no significant signs of inefficient integration. The previous differences found by Grant and Seitz [J. Acoust. Soc. Am. 104, 2438-2450 (1998)] must be due to their measures of efficiency, which appear to be invalid and/or conflate information with integration efficiency. Finally, the descriptive ability of the FLMP is shown to be theoretically informative and not simply the model's ability to describe any possible outcome.

Humans↗
PubMed2000

A clinical trial of the Buteyko Breathing Technique in asthma as taught by a video.

The Buteyko Breathing Technique (BBT) is promoted as a drug-free asthma therapy. It is based on the premise that raising blood PaCO2 through hypoventilation can treat asthma. Our study was designed to examine whether the Buteyko Breathing Technique, as taught by a video, is an efficacious asthma therapy. Thirty-six adult subjects with mild to moderate asthma were randomized to receive either a BBT or placebo video to watch at home twice per day for 4 weeks. Asthma-related quality of life, peak expiratory flow (PEF), symptoms, and asthma medication intake were assessed both before and after intervention. Our results demonstrated a significant improvement in quality of life among those assigned to the BBT compared with placebo (p = 0.043), as well as a significant reduction in inhaled bronchodilator intake (p = 0.008). We conclude that the BBT may be effective in improving the quality of life and reducing the intake of inhaled reliever medication in patients with asthma. These results warrant further investigation.

Adult↗
PubMed2000

Perception of facial features and face-to-face communications in space.

This paper examines how human face-to-face communications may be compromised by exposure to the microgravity environment of space. Although efficient face-to-face communications are acknowledged to be essential for astronauts to work safely and effectively, the space environment causes facial edema, and allows speakers and listeners to confront one another in multiple orientations that can potentially interfere with many important non-linguistic communication cues. In addition, high background noises in space shuttles and stations can mask auditory messages. Currently, the effects of spaceflight on the ability to identify facial features, to read lips, to integrate visual and auditory sensory information, and to interpret spoken messages in noisy environments while the speakers are at various orientations with respect to the listeners, are virtually unknown. Ground-based experiments conducted in our laboratory with computer-displayed facial images presented at various orientations have suggested how non-linguistic cues may be degraded by changes in the retinal orientations of facial images. The results of our ground-based studies illustrating impaired recognition of facial features in non-erect images are described, their implications for effective face-to-face communications among astronauts in space are discussed, and two experiments that can quantify the effects of microgravity on face-to-face communications in space are outlined.

Adult↗
PubMed1999

Hormone replacement therapy: a survey of Ontario physicians' prescribing practices.

BACKGROUND: Although much has been written about hormone replacement therapy (HRT), there are few clearcut recommendations on its use. The purpose of this study was to determine Ontario physicians' patterns of and reasons for prescribing HRT, their use of pretreatment investigations and their surveillance of HRT users, and to determine whether physicians' reported practice is consistent with existing recommendations. METHODS: A self-administered questionnaire was mailed to a nonproportional stratified sample of 327 Ontario physicians (23.9% gynecologists, 76.1% general practitioners/family physicians [GP/FPs]). Outcome measures were ranking of reasons for prescribing HRT, nature of preliminary testing, regimens prescribed, duration of HRT and frequency of follow-up. RESULTS: The response rate was 60.9% overall (70.9% of the gynecologists, 58.3% of the GP/FPs). Prevention of osteoporosis was reported by 97.4% as an important or very important reason for prescribing HRT; prevention of coronary artery disease was important or very important for 89.3%. When considering whether or not to prescribe HRT, 97.3% stated that breast cancer was an important or very important factor. When presented with hypothetical cases, 97.0% stated that they would prescribe combined estrogen-progestin for a symptomatic woman with an intact uterus; 13.6% stated that they would do so for a woman with no uterus. Most reported that they would prescribe HRT for 12 or more years (73.3%) and would follow up patients every 1 to 2 years (70.6%). INTERPRETATION: Despite controversy about HRT in the published literature, the Ontario physicians surveyed reported similar reasons and patterns of prescribing, pretreatment investigations, and surveillance of postmenopausal women using HRT. These results suggest that Ontario physicians' knowledge about HRT is consistent with recommendations in the published literature.

Adult↗