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Biomedical subjects

A C Lee

Publications and source records attributed to A C Lee.

At least 37 records · Page 2Linked to original sources
PubMed2000

Short-wavelength automated perimetry and standard perimetry in the detection of progressive optic disc cupping.

OBJECTIVE: To compare progression in short-wavelength automated perimetry (SWAP) and white-on-white (standard) perimetry in eyes with progressive glaucomatous changes of the optic disc detected by serial stereophotographs. METHODS: Forty-seven glaucoma patients with at least 2 disc stereophotographs more than 2 years apart, along with standard perimetry and SWAP examinations within 6 months of each disc photo of the same eye, were included in the study. The mean follow-up time was 4.1 years (range, 2.0-8.9 years). Baseline and follow-up stereophotographs were then graded and compared for the presence of progression. Progression in standard perimetry and SWAP, using the Advanced Glaucoma Intervention Study scoring system and a clinical scoring system, was compared between eyes with progressive change on stereophotographs and those without. RESULTS: Twenty-two of 47 eyes showed progressive change by stereophotographs. There was a statistically significant difference in the mean change in Advanced Glaucoma Intervention Study scores for both standard perimetry (P<.004) and SWAP (P<.001) between the progressed and nonprogressed groups. The sensitivity, specificity, and area under the receiver operator characteristic curve were higher using SWAP than standard perimetry when evaluated by either algorithm. This was statistically significant only in the area under the receiver operator characteristic curve for the Advanced Glaucoma Intervention Study scoring system (P =.04). CONCLUSIONS: Short-wavelength automated perimetry identified more patients than standard perimetry as having progressive glaucomatous changes of the optic disc. Compared with standard perimetry, SWAP may improve the detection of progressive glaucoma. Arch Ophthalmol. 2000;118:1231-1236

Aged↗
PubMed2000

Chiropractic care for children.

OBJECTIVE: To describe the practice characteristics and pediatric care of chiropractors. STUDY DESIGN: Cross-sectional, descriptive survey. SETTING: Chiropractic practices in the Boston, Mass, metropolitan area. PARTICIPANTS: One hundred fifty licensed chiropractors. MAIN OUTCOME MEASURES: Demographics, practice characteristics, and fee structure. Practitioners were also asked about their approach to childhood immunizations and a clinical scenario. Data were analyzed using simple descriptive statistics. RESULTS: Ninety (60%) chiropractors responded. All were white and 65% were men. Respondents had on average 122 patient visits weekly, of which 13 (11%) were from children and adolescents. Typical visit frequency ranged from 1 to 3 times weekly. Average visit fees were $82 and $38 (initial and follow-up) and 49% of the fees were covered by insurance. Seventy percent of the respondents recommended herbs and dietary supplements. For pediatric care, 30% reported actively recommending childhood immunizations; presented with a hypothetical 2-week-old neonate with a fever, 17% would treat the patient themselves rather than immediately refer the patient to a doctor of medicine, doctor of osteopathy, or an emergency facility. CONCLUSIONS: Children and adolescents constitute a substantial number of patients in chiropractics. An estimated 420000 pediatric chiropractic visits were made in the Boston metropolitan area in 1998, costing approximately $14 million. Pediatric chiropractic care is often inconsistent with recommended medical guidelines. National studies are needed to assess the safety, efficacy, and cost of chiropractic care for children.

Adolescent↗
PubMed2000

Comparison of long-term variability for standard and short-wavelength automated perimetry in stable glaucoma patients.

PURPOSE: To quantify and compare, on a point-by-point basis, the long-term variability of standard and short-wavelength automated perimetry in a group of stable glaucoma patients. METHODS: From a group of 53 glaucoma patients experienced in visual field testing, we identified one eye, randomly chosen, from each of 25 glaucoma patients whose condition was found to be stable, based on both standard and short-wavelength automated perimetry visual field criteria. On each of three visits during a period of up to 3 months, each patient performed one standard and one short-wavelength automated perimetry 24-2 visual field in a random order on a Humphrey visual field analyzer. The long-term variability (also referred to as test-retest variability) was defined as the SD of the three threshold decibel values at each test location. The long-term variability for each test point (mean +/- SD) was determined separately for both standard visual fields and short-wavelength automated perimetry. RESULTS: With all 52 test locations of the 24-2 field averaged, the global long-term variability, mean (+/- SD) for standard visual fields and short-wavelength automated perimetry was 2.37 +/- 2.03 dB (95% confidence interval, 2.26-2.48 dB) and 2.92 +/- 2.03 dB (95% confidence interval, 2.81-3.03 dB), respectively (P <.0001). In 16 of the 52 visual field locations, long-term variability on short-wavelength automated perimetry was significantly higher than long-term variability on standard visual fields. In addition, the long-term variability increased with greater distance from the point of fixation for both standard visual fields and short-wavelength automated perimetry. The long-term variability decreased closer to fixation, more for standard visual fields than for short-wavelength automated perimetry. CONCLUSIONS: In a group of stable glaucoma patients, mean long-term variability was 0.55 dB higher for short-wavelength automated perimetry than for standard visual fields. This needs to be taken into consideration when serial visual fields are evaluated for change.

Adult↗
PubMed2000

Asymmetric frontal activation during episodic memory: the effects of stimulus type on encoding and retrieval.

Recent functional neuroimaging studies have suggested that the left prefrontal cortex is preferentially involved in the encoding of episodic memory whilst the right prefrontal cortex is preferentially involved in the retrieval of episodic memory, irrespective of the type (e.g. modality) of information being remembered. In the present PET activation study, a 2 x 2 design was employed to investigate the relationship between encoding and retrieval of verbal and non-verbal material in episodic memory. Accordingly, seven healthy volunteers were scanned whilst encoding and then recalling stimuli which either emphasised visual or verbal processes. When encoding and retrieval tasks were compared directly, significantly greater prefrontal activation was observed in the encoding conditions, regardless of modality, although these changes were bilaterally distributed. In contrast when the verbal and visual memory tasks were compared directly, the former was associated with rCBF changes that were predominantly located in the left lateral frontal cortex whilst the latter was associated with rCBF changes that were predominantly located in the right lateral frontal cortex. These results suggest that encoding and retrieval may actually involve similar regions of the lateral prefrontal cortex when all factors relating to the type of stimulus material (i.e. modality), are appropriately controlled.

Adult↗
PubMed2000

Septic arthritis in hemophilia with central venous catheter: a case report.

A case is reported of septic arthritis in a child with human immunodeficiency virus-negative hemophilia A associated with a Staphylococcus aureus catheter-associated septicemia. The infection occurred in relation to the use of a totally implantable central venous catheter. The organism was eventually eradicated with antibiotics injected via the catheter. With increasing use of such catheters in the hemophilic population, clinicians should be alerted to the possibility of septic arthritis for prompt diagnosis and treatment.

Adolescent↗
PubMed2000

Practice patterns of massage therapists.

OBJECTIVES: To describe the practice patterns of licensed massage therapists (LMTs). DESIGN: Cross-sectional survey. SUBJECTS: One hundred and twenty-six (126) massage practices randomly selected from the Greater Boston Area yellow pages. OUTCOMES MEASURES: Practitioner demographics, training, practice characteristics, and fees. RESULTS: The response rate was 65%. Most respondents were Caucasian (95%) and female (80%). Their mean age was 41 years old. Half held a college degree; on average, practitioners received 1000 hours of training in massage therapy. The majority were in group practices (59%) and saw an average of 20 patients per week. The typical visit lasted 50-60 minutes; the cost was $60 and rarely covered by insurance (5%). Half of respondents offered sliding scales to patients, but only 11% accepted Medicaid patients. Respondents reported less than 1 visit per week from pediatric and adolescent patients (<21 years old). CONCLUSIONS: Most LMTs are female and Caucasian. The costs of massage therapy are almost entirely paid out-of-pocket by patients (95%). LMTs infrequently care for children.

Adult↗
PubMed2000

Small incision nonendoscopic browlift.

PURPOSE: To determine the efficacy of a nonendoscopic brow/forehead lift. METHODS: Case series of 12 patients. Small scalp and upper eyelid blepharoplasty incisions were used to elevate the brows/forehead and perform protractor myectomy. RESULTS: All patients achieved an aesthetically pleasing eyebrow and forehead lift with reduction of vertical and horizontal glabellar creases. Complications included one patient who experienced prolonged ecchymosis after corrugator muscle resection and one patient who had asymmetric lid folds after surgery. The length of follow-up ranged from 9 to 35 months. CONCLUSIONS: The small incision nonendoscopic browlift technique provides a useful alternative to the endoscopic approach.

Adult↗
PubMed2000

Homeopathy and naturopathy: practice characteristics and pediatric care.

OBJECTIVE: To describe the practice characteristics and pediatric care of homeopathic practitioners (HPs) and naturopathic doctors (NDs). DESIGN: Cross-sectional, descriptive survey. SETTING: Homeopathic and naturopathic practices in Massachusetts. PARTICIPANTS: Homeopathic practitioners (N = 42) and NDs (N = 23) identified from the yellow pages, regional and national society membership lists, schools, magazine advertisements, and by word-of-mouth. The response rate was 55% (23/42) for HPs and 65% (15/23) for NDs. MAIN OUTCOME MEASURES: Demographics, practice characteristics, fee structure, and amount of pediatric care. Practitioners were asked for their approach to childhood immunizations and to treating a febrile neonate. Data were analyzed using simple descriptive statistics. RESULTS: Almost all respondents were white. Among the HPs, 13 (57%) were licensed medical doctors. Naturopathic doctors and HPs reported having an average of only 25 to 40 patient visits per week, but children and adolescents accounted for up to one third of these visits. Nearly all reported treating children, but fewer than half of the practitioners reported any formal pediatric training. Initial patient visits typically lasted more than 1 hour and cost $140 to $150. Follow-up visits were scheduled every 4 to 6 weeks and lasted more than 30 minutes on average. Insurance covered less than one third of the patient visits, and sliding scale payments were offered by less than half of the respondents. Most practitioners reported that they did not actively recommend immunizations and fewer than half of the nonphysician practitioners reported that they would refer a 2-week-old neonate with a fever to a medical doctor or emergency medical facility. CONCLUSIONS: Many patients using homeopathy and naturopathy are children. Visits to these providers are frequent and fees are primarily paid out-of-pocket. Failure on the part of these providers to recommend immunizations or recognize potentially serious illnesses is cause for concern.

Adult↗
PubMed2000

Episodic memory meets working memory in the frontal lobe: functional neuroimaging studies of encoding and retrieval.

Recent functional-neuroimaging studies have provided a wealth of new information suggesting that regions of the prefrontal cortex play a role in episodic memory encoding and retrieval. This review seeks to evaluate the results of these studies in the context of one general model that has proposed that the left prefrontal cortex is preferentially involved in episodic memory encoding, whereas the right prefrontal cortex is preferentially involved in episodic memory retrieval, irrespective of the type (e.g., modality) of information being remembered. The origins of this framework are considered in some detail and then all relevant functional-neuroimaging studies are critically reviewed. The results of this review fail to provide support for the functional-asymmetry model, suggesting instead that episodic memory encoding and retrieval may actually involve similar regions of the lateral prefrontal cortex when all factors relating to the type of stimulus material (i.e., modality), are appropriately controlled.

Brain Mapping↗
PubMed1999

Ras proteins induce senescence by altering the intracellular levels of reactive oxygen species.

Human diploid fibroblasts eventually lose the capacity to replicate in culture and enter a viable but nonproliferative state of senescence. Recently, it has been demonstrated that retroviral-mediated gene transfer into primary fibroblasts of an activated ras gene (V12ras) rapidly accelerates development of the senescent phenotype. Using this in vitro system, we have sought to define the mediators of Ras-induced senescence. We demonstrate that expression of V12Ras results in an increase in intracellular and in particular, mitochondrial reactive oxygen species. The ability of V12Ras to induce growth arrest and senescence is shown to be partially inhibited by coexpression of an activated rac1 gene. A more dramatic rescue of V12Ras-expressing cells is demonstrated when the cells are placed in a low oxygen environment, a condition in which reactive oxygen species production is inhibited. In addition, in a 1% oxygen environment, Ras is unable to trigger an increase in the level of the cyclin-dependent kinase inhibitor p21 or to activate the senescent program. Under normoxic (20% O2) conditions, the V12Ras senescent phenotype is demonstrated to be unaffected by scavengers of superoxide but rescued by scavengers of hydrogen peroxide. These results suggest that in normal diploid cells, Ras proteins regulate oxidant production and that a rise in intracellular H2O2 represents a critical signal mediating replicative senescence.

Apoptosis↗
PubMed1999

Late ophthalmological complications after total body irradiation in non-human primates.

PURPOSE: To investigate the long-term effects of total body irradiation (TBI) on the incidence and time course of ocular complications. MATERIALS AND METHODS: Rhesus monkeys treated with TBI photon doses up to 8.5 Gy and proton doses up to 7.5 Gy were studied at intervals up to 25 years post-irradiation. They were compared with control groups with a similar age distribution. Cataract formation and ocular fundus lesions were scored according to a standardized protocol. Fluorescein angiography and histopathology was performed in selected animals. RESULTS: Cataract formation occurred after a latent period of 3-5 years. Significant cataract induction was observed for photon-doses of 8 and 8.5 Gy and beyond 20 years after proton irradiation. The severity of the lesions represents significant impairment of vision and would require cataract surgery if similar results occurred in human bone marrow transplant patients. Fluorescein angiography demonstrated a normal pattern of retinal vessels in 13 out of 14 animals (93%) from the irradiated group and in eight out of nine animals (89%) from the control group. No additional lesions apart from age-related degenerative changes could be demonstrated. Histological evaluation revealed no radiation-associated vasculopathy. CONCLUSIONS: Radiation alone for doses up to 8.5 Gy of photons does not carry a potential risk for fundus pathology, whereas clinically important cataract induction should be anticipated within 5 years after photon doses of 8.0 and 8.5 Gy and proton doses in excess of 2.5 Gy.

Age Factors↗
PubMed1999

Classification and behavior of canine mammary epithelial neoplasms based on life-span observations in beagles.

As part of a study of the effects of low-level radiation, 1,343 Beagles, including 671 males and 672 females, were evaluated over their full lifetime for the occurrence of mammary neoplasia; there were 139 control males and 138 control females and 532 irradiated males and 534 irradiated females. All nodules found in surgical specimens or at necropsy were evaluated histologically. The overall incidence, metastasis and recurrence rates, and contribution to mortality of mammary neoplasms were determined. Based on this unique opportunity to correlate morphologic characteristics with ultimate biological behavior of all mammary tumors in a defined canine population, we propose a histogenetically based reclassification of epithelial mammary tumors. Of the 672 female dogs, 70.8% (476) had at least one mammary neoplasm; 60.7% (408) had more than one. Two male dogs had mammary neoplasms. Of 1,639 mammary carcinomas in the 672 females, 18.7% (307) were classified as ductular carcinomas (arising from the small interlobular or intralobular ductules), whereas 80.7% (1,322) were classified as adenocarcinomas of other histogenetic origin. Of 73 fatal carcinomas, ductular carcinomas accounted for 48 fatalities (65.8%), whereas other adenocarcinomas accounted for only 20 fatalities (27.4%). Radiation had no effect on this ratio. Ductular carcinomas also had a higher rate of metastasis than did adenocarcinomas. Existing classifications of mammary carcinomas do not recognize the characteristic morphologic features, the degree of malignancy, and the prognostic importance of these ductular carcinomas. Metastasis rates did not differ between simple and complex carcinomas or between those lesions and adenocarcinomas in mixed tumors. True carcinosarcomas metastasized more frequently (100%, or 5/5) than did adenocarcinomas in mixed tumors (34.4%, or 22/64), emphasizing the importance of not lumping these tumors under the classification of malignant mixed tumors.

Adenocarcinoma↗
PubMed1999

Survey of acupuncturists: practice characteristics and pediatric care.

OBJECTIVE: To describe the practice characteristics and pediatric care provided by licensed acupuncturists. DESIGN: Cross-sectional survey. SETTING: Boston metropolitan area. SUBJECTS: 227 licensed acupuncturists were surveyed; 140 (62%) responded. MAIN OUTCOME MEASURES: (1) DEMOGRAPHICS, (2) practice characteristics, (3) pediatric care, (4) recommendations of peers recognized as experts in pediatric acupuncture. RESULTS: (1) DEMOGRAPHICS: 70% Caucasian, 61% female; (2) practice characteristics: average of 39 visits weekly with an average charge of $54 for a 57-minute visit; patients were typically scheduled for follow-up once or twice weekly; only 5% of fees were covered by insurance; 80% recommended herbal remedies and 66% dispensed herbs in the office; (3) few acupuncturists treated more than one child per week; most used non-needle techniques or Japanese-style acupuncture to stimulate points in children; 85% would refer a febrile two-week-old infant immediately to a physician; (4) only 17 acupuncturists were recommended by three or more peers and saw three or more patients weekly; their practices were all in wealthy suburban areas. CONCLUSIONS: Most acupuncturists in the Boston area are Caucasian and female. Compared with physicians, they schedule patients for more frequent follow-up, allocate more time, are less likely to be reimbursed by insurance, and treat fewer children. Additional studies are needed to assess effectiveness, quality, and access to acupuncture services for adults and children.

Acupuncture Therapy↗