Biomedical subjects
M Gordon
Publications and source records attributed to M Gordon.
Words, art, body and memory: readings from a writer.
This essay considers the consequences of childhood experiences with family illness on future adult sensibilities. Novelist and memoirist Mary Gordon describes her father's early death from heart disease and her childhood responsibilities toward her mother who was chronically ill with polio. She examines the relations between the ill body and the rituals and teachings of Catholicism and, by implication, all religious imagings of the body. By detailing her current caregiving responsibilities toward her mother, who is now homebound with Alzheimer disease, she scrutinizes the responses of the healthy toward the ill. She cites passages from her own novels--The Other Side, The Shadow Man, and Spending--in which characters' bodies fail and sicken. By examining these retrospective and prospective experiences with other people's ailments, Gordon exhorts medical students and doctors to tend to the bodies in their care with skill, with vision, and with words. She joins fellow writer Joseph Conrad in his task: "by the power of the written word to make you hear, to make you feel; it is, before all, to make you see."
Report of the Sixth International Workshop on Human Chromosome 11 Mapping 1998. Nice, France, May 2-5, 1998.
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Attention deficit hyperactivity disorder: diagnosis and management in the USA.
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Application of lacZ transgenic mice to cell lineage studies.
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The paradox of the low-renin state in diabetic nephropathy.
Although diabetic nephropathy is often a low renin state, the renin system appears to be implicated in its pathogenesis. In this study, it was hypothesized that the low plasma renin activity (PRA) is misleading, masking and perhaps reflecting an activated intrarenal renin system. PRA and renal vascular responses (inulin and para-aminohippurate clearance) to graded doses of an angiotensin II (AngII) antagonist, irbesartan, were assessed in eight healthy volunteers and 12 patients with type 2 diabetes mellitus and nephropathy on a 10 mmol Na intake, to activate the renin system. Basal PRA was suppressed in type 2 diabetes mellitus compared with the healthy subjects (0.58 +/- 0.14 versus 1.58 +/- 0.28 ng/L per s, mean +/- SEM; P < 0.01). Despite the low PRA, renal perfusion rose more in response to irbesartan in type 2 diabetes mellitus (714 +/- 83 to 931 +/- 116 ml/min; P = 0.002) than normal (624 +/- 29 to 772 +/- 49 ml/min; P = 0.008). The youngest patients were hyperfiltrating and showed the largest rise in renal plasma flow in response to irbesartan, whereas renal plasma flow rose less and GFR fell in patients with low basal GFR. PRA rose in response to irbesartan more gradually in the patients with type 2 diabetes mellitus, but ultimately matched the normal response. To account for the apparent paradox of a heightened renal hemodynamic response to an AngII antagonist in the face of a low PRA in type 2 diabetes mellitus, and the rise in PRA following the AngII antagonist, it is proposed that there is increased intrarenal AngII production in type 2 diabetes mellitus. This increase could account for suppressed circulating renin, the exaggerated renal vasodilator response to irbesartan, and the therapeutic effectiveness of interrupting the renin system in diabetic nephropathy.
36 month intermittent cyclical etidronate treatment in patients with established corticosteroid induced osteoporosis.
OBJECTIVE: To determine the longterm safety and efficacy of etidronate therapy in patients in whom corticosteroid induced bone loss has already occurred. METHODS: We performed a 36 month observational cohort study in which all data were obtained from Canadian Database of Osteoporosis and Osteopenia (CANDOO) patients. The etidronate group consisted of 24 patients who received 400 mg of etidronate disodium for 14 days, followed by 76 days of calcium carbonate (500 mg of elemental calcium), repeated every 3 mo; the control group included 37 patients who received calcium carbonate 500 to 1000 mg daily. Outcome measurements included changes within groups from baseline and differences between groups in the bone mineral density (BMD) of the lumbar spine, femoral neck, and trochanter at 12, 24, and 36 months. The incidence of vertebral fractures was also determined. RESULTS: Etidronate therapy resulted in a meaningful percentage increase from baseline in lumbar spine BMD, primarily during the first 24 months of treatment, and this increase was sustained for the remainder of the 36 month study period (5.2%; p = 0.016). Analysis of covariance revealed a significant percentage difference (SD) between groups in lumbar spine BMD at 12 [5.5 (13.5) percent; p = 0.003] and 24 months [6.0 (17.4) percent; p = 0.011] in favor of the etidronate group. After 3 years of therapy, one patient (4%) experienced one vertebral fracture in the etidronate group, whereas 3 patients (8%) experienced 5 vertebral fractures in the control group. CONCLUSION: Etidronate treatment administered for 36 months reversed lumbar spine bone loss, and appeared to be safe in patients with established corticosteroid induced osteoporosis.
Intraoperative facial nerve monitoring: a comparison between electromyography and mechanical-pressure monitoring techniques.
OBJECTIVES: To examine the hypothesis that for intraoperative facial nerve monitoring, an EMG monitor is more sensitive than a mechanical-pressure monitor. To compare the threshold sensitivity of the two facial nerve monitoring methods-mechanical-pressure versus EMG--by using them simultaneously during surgery. To assess and compare their true- and false-positive responses in otologic and neurotologic procedures. SETTING: A tertiary referral private otology/neurotology practice. STUDY DESIGN: Prospective case-controlled study. PATIENTS AND METHODS: The facial nerve of 46 consecutive patients undergoing various otologic and neurotologic procedures was stimulated intraoperatively using a pulsed constant-current. Facial responses were monitored using the Silverstein WR-S8 Monitor/Stimulator and the Brackmann EMG System simultaneously. The threshold (i.e., minimal) current level required to elicit a response from each monitor was recorded. Monitor responses to facial nerve manipulation (including false-positive responses) were assessed by continuous recording of all responses, using the Wiegand Monitoring System, and noting the causative event for each response. RESULTS: The EMG monitor responded to lower current threshold (p < 0.001) in every surgical procedure and for every nerve segment studied. However, the average threshold difference was <0.05 mAmps and in clinical practice, when using above threshold stimulation, becomes negligible. In posterior fossa surgery, the EMG monitor showed higher sensitivity by responding earlier to various manipulations of the bare facial nerve. The EMG had more false-positive responses than the mechanical-pressure monitor. CONCLUSIONS: In otologic surgery, if monitoring is required, the mechanical-pressure monitor is used. In neurotologic surgery, both monitors are used simultaneously.
The evolution of clinical trials: inclusion and representation.
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Impaired spatial navigation learning in transgenic mice over-expressing heme oxygenase-1.
Transgenic mice expressing heme oxygenase-1 (HO-1) using the neuron-specific enolase promoter were impaired in learning the Morris water maze compared to nontransgenic littermates. The memory of the HO-1 mice for the location of the platform was similarly impaired when tested using a probe trial after 7 training blocks, but performance on visible platform trials was similar for both groups of mice. Importantly, both HO-1 and nontransgenic mice had normal sensorimotor function, and performed the same on a Y-maze alternation task, highlighting the specificity of memory deficit in the spatial navigation task. These results suggest that carbon monoxide, one product of HO-1 activity, interferes in the development of spatial navigation memory, and may play a role in normal memory function.
Funding Canada's health care system: a tax-based alternative to privatization.
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The anatomy of a clinical information system.
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Enhanced intestinal adenomatous polyp formation in Pms2-/-;Min mice.
Analysis of two human familial cancer syndromes, hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis, indicates that mutations in either one of four DNA mismatch repair gene homologues or the adenomatous polyposis coli (APC) gene, respectively, are important for the development of colorectal cancer. To further investigate the role of DNA mismatch repair in intestinal tumorigenesis, we generated mice with mutations in both Apc and the DNA mismatch repair gene, Pms2. Whereas Pms2-deficient mice do not develop intestinal tumors, mice deficient in Pms2 and heterozygous for Min, an allele of Apc, develop approximately three times the number of small intestinal adenomas and four times the number of colon adenomas relative to Min and Pms2+/-;Min mice. Although Pms2 deficiency clearly increases adenoma formation in the Min background, histological analysis indicated no clear evidence for progression to carcinoma.
The Glaucoma Symptom Scale. A brief index of glaucoma-specific symptoms.
OBJECTIVE: To develop a brief symptom survey specific for persons with glaucoma, the Glaucoma Symptom Scale (GSS). DESIGN: Cross-sectional study of symptoms, functional impairment, and vision-targeted health-related quality of life among persons with glaucoma. PATIENTS: A sample of 147 persons with glaucoma among a broad range of treatment categories from 4 tertiary care glaucoma centers and 44 persons without eye disease enrolled from the same 4 centers. MAIN OUTCOME MEASURES: Participants completed a modified version of the Ocular Hypertension Treatment Study 10-item symptom checklist. Participants also completed 2 vision-specific measures, the National Eye Institute Visual Function Questionnaire and the VF-14. Participants underwent a clinical evaluation, including ocular and medical history, dilated ophthalmic examination, and Humphrey 24-2 automated visual field testing. RESULTS: The GSS has 2 underlying domains that demonstrate sufficient internal consistency reliability for between-group comparisons. The GSS discriminates well between persons with and without glaucoma. Additionally, tests of association with clinical markers of glaucoma severity support the clinical validity of the measure and tests of association with established vision-targeted measures provide evidence of construct validity. CONCLUSION: The simplicity, brevity, and psychometric properties of the GSS support its use in clinical practice and research to quantify symptoms in patients with glaucoma and to assist in investigations concerning the effect of glaucoma and treatments.
Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study.
OBJECTIVE: This report presents the results of a randomized clinical trial of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK). DESIGN: A randomized, prospective multicenter clinical trial. PARTICIPANTS: A total of 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. The mean preoperative manifest refraction spherical equivalent was -9.23 diopters (D) in the PRK group and -9.30 D in the LASIK group. INTERVENTION: All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure using the Summit Apex excimer laser. Attempted corrections ranged from 6.00 to 15.00 D. MAIN OUTCOME MEASURES: Data on uncorrected and spectacle-corrected visual acuity, predictability,and stability of refraction, corneal haze, and flap complications were analyzed. Patients were observed for up to 6 months. RESULTS: One day after surgery, 0 (0.0%) and 3 (4.5%) eyes in the PRK group saw 20/20 and 20/40 or better uncorrected, respectively, while 7 (10%) and 48 (68.6%) eyes in the LASIK group saw 20/20 and 20/40 or better, respectively. At 6 months after PRK, 13 (19.1%) and 45 (66.2%) eyes saw 20/20 and 20/40 or better, respectively, while after LASIK, 16 (26.2%) and 34 (55.7%) eyes saw 20/20 and 20/40 or better, respectively (odds ratio = 0.56 for likelihood of uncorrected visual acuity < 20/40 for PRK vs. LASIK, 95% confidence interval [CI] = 0.31-1.19). After PRK, 39 eyes (57.4%) were within 1.0 D of attempted correction compared with 24 eyes (40.7%) in the LASIK group (odds ratio = 0.50 for likelihood fo undercorrection 1.0 D for PRK vs. LASIK, 95% CI = 0.24-1.04); however, the standard deviation of the predictability was similar between groups: 1.01 D for PRK and 1.22 D for LASIK. From months 1 to 6, there was an average regression of 0.89 D in the PRK group and 0.55 D in the LASIK group. After PRK, eight eyes (11.8%) had a decrease in spectacle-corrected visual acuity of two Snellen lines or more; after LASIK, two eyes (3.2%) had a decrease of two lines or more (odds ratio = 3.89 for risk of loss of spectacle-corrected visual acuity for PRK vs. LASIK, 95% CI = 0.71-21.30). Only two eyes had postoperative spectacle-corrected visual acuity less than 20/32, however. CONCLUSIONS: Although improvement in uncorrected visual acuity is more rapid in LASIK than in PRK, efficacy outcomes in the longer term generally are similar between the two procedures. There is a greater tendency toward undercorrection in LASIK eyes using the specific laser and nomogram in this study, but the scatter in achieved versus attempted correction is similar, suggesting little difference in the accuracy of the two procedures. A suggestion of decreased propensity for loss of spectacle-corrected visual acuity in LASIK eyes requires further investigation.
Temporal processing across frequency channels by FM selective auditory neurons can account for FM rate selectivity.
Auditory neurons tuned to the direction and rate of frequency modulations (FM) might underlie the encoding of frequency sweeps in animal vocalizations and formant transitions in human speech. We examined the relationship between FM direction and rate selectivity and the precise temporal interactions of excitatory and inhibitory sideband inputs. Extracellular single-unit recordings were made in the auditory midbrains of eight mustached bats. Up- and down-sweeping linear FM stimuli were presented at different modulation rates in order to determine FM selectivity. Brief tone pairs with varying interstimulus delays were presented in a forward masking paradigm to examine the relative timing of excitatory and inhibitory inputs. In the 33 units for which tone pair data were collected, a correspondence existed between FM rate selectivity and the time delays between paired tones. Moreover, FM directional selectivity was strongly linked to rate selectivity, because directional preferences were expressed only at certain rates and not others. We discuss how abnormalities in the relative timing of inputs could alter or abolish the selectivity of such neurons, and how such a mechanism could account for the perceptual deficits for formant transitions seen in certain children with phonological deficits.