Metamorphic In(0.20)Ga(0.80)As p-i-n photodetectors grown on GaAs substrates for near infrared applications.

The growth and performance of top-illuminated metamorphic In(0.20)Ga(0.80)As p-i-n photodetectors grown on GaAs substrates using a step-graded In(x)Ga(1-x)As buffer is reported. The p-i-n photodetectors display a low room-temperature reverse bias dark current density of ~1.4×10(-7) A/cm(2) at -2 V. Responsivity and specific detectivity values of 0.72 A/W, 2.3×10(12) cm·Hz(1/2)/W and 0.69 A/W, 2.2×10(12) cm·Hz(1/2)/W are achieved for Yb:YAG (1030 nm) and Nd:YAG (1064 nm) laser wavelengths at -2 V, respectively. A high theoretical bandwidth-responsivity product of 0.21 GHz·A/W was estimated at 1064 nm. Device performance metrics for these GaAs substrate-based detectors compare favorably with those based on InP technology due to the close tuning of the detector bandgap to the target wavelengths, despite the presence of a residual threading dislocation density. This work demonstrates the great potential for high performance metamorphic near-infrared InGaAs detectors with optimally tuned bandgaps, which can be grown on GaAs substrates, for a wide variety of applications.

Direct measurement of quantum confinement effects at metal to quantum-well nanocontacts.

Model metal-semiconductor nanostructure Schottky nanocontacts were made on cleaved heterostructures containing GaAs quantum wells (QWs) of varying width and were locally probed by ballistic electron emission microscopy. The local Schottky barrier was found to increase by approximately 0.140 eV as the QW width was systematically decreased from 15 to 1 nm, due mostly to a large (approximately 0.200 eV) quantum-confinement increase to the QW conduction band. The measured barrier increase over the full 1 to 15 nm QW range was quantitatively explained when local "interface pinning" and image force lowering effects are also considered.

Percutaneous endoscopic gastrostomy (PEG) in patients with ALS and bulbar dysfunction.

OBJECTIVE: To compare characteristics of ALS patients with and without percutaneous endoscopic gastrostomy (PEG). METHODS: Using the ALS Patient Care Database, data from patients with and without PEG with ALS Functional Rating Scale-bulbar subscale (ALSFRSb) scores < or = 5 were analyzed; follow-up data were also collected. RESULTS: PEG use was markedly increased with declining ALSFRSb scores. Demographics did not differ, but ALSFRS composite scores and bulbar and arm subscale scores were lower (P<0.0001). PEG patients used significantly more assistive devices, multidisciplinary care, home care nurses and aides, had more frequent physician and emergency department visits and hospital admissions (P<0.0001), and had lower health status based on the mini-SIP scale (P=0.0047). PEG use varied greatly between ALS centers. In the follow-up study, positive impact of PEG was noted in 79 % of PEG patients but in only 37.5% of patients who received PEG later, based on a small number of patients. PEG use showed no survival benefit. CONCLUSION: Patients did not receive PEG until bulbar function was severely reduced and overall ALS had markedly progressed. PEG may have been performed too late to demonstrate survival benefits. Aggressive proactive nutritional management appears essential in patients with ALS. To determine whether PEG provides benefits, it must be performed at earlier stages of the disease and prospectively studied.

Breast-feeding and smoking habits among Israeli women.

BACKGROUND: Many women stop smoking before or during pregnancy, or while breast-feeding (nursing). OBJECTIVES: To assess the relation between breast-feeding and smoking habits. METHODS: A survey was conducted among 920 women attending family health clinics (group 1) and a maternity department (group 2) on their breast-feeding and smoking habits. RESULTS: A total of 156 women (16.95%) smoked during pregnancy. A significant correlation was found between breast-feeding and not smoking after delivery (P = 0.009 in group 1, P = 0.03 in group 2). A higher tendency to nurse was found among women with an uneventful pregnancy, who vaginally delivered a singleton at term weighing 2,500-4000 g, and who received guidance on breast-feeding. CONCLUSION: Professional guidance in favor of breast-feeding is crucial to increase the rate of nursing. Encouraging breast-feeding will probably decrease the rate of cigarette smoking.

Quantitative assessment of motor fatigue in amyotrophic lateral sclerosis.

Motor fatigue is a common complaint in patients with amyotrophic lateral sclerosis (ALS), but is often excluded, unlike weakness, from the clinical assessment of these patients. This could be due to the complexity and often painful assessment techniques of this motor deficit. This study examines the feasibility of quantitative assessment of motor fatigue by modifying presently available force measurements. The relationship between weakness and fatigue in ALS patients was also examined. Fifty-four ALS patients and 39 normal control subjects performed 30 s of sustained maximal voluntary isometric contraction (MVIC) of elbow flexors (EF), knee extensors (NE), and ankle dorsiflexors (DF), using a computerized force measurement system and standardized testing procedures. Fatigue index (FI) was digitally calculated, from the force-time curve, as the percentage of MVIC unable to be sustained over the 30-s period. Fatigue was greater in ALS patients than in normal control (mean=23% vs. 15%) in all muscles including muscles that were not clearly weak. Weakness and fatigue were poorly correlated in ALS patients and may be independent measures of the pathogeneses of ALS.

Training clinical researchers in neurology: we must do better.

The pace of scientific discoveries, the increasing complexity of managing patients, and the runaway cost of neurological services have created an urgent need for a wide range of clinical research in neurology. Despite increasing recognition of this need and recent increases in funding for training clinical investigators, neurologists conducting cellular and molecular investigations are more likely to join faculties, maintain research careers, and attain academic advancement. Because academic departments of neurology are successful in producing and nurturing basic science researchers, why aren't they just as triumphant in spawning clinical investigators? This crisis in the preparation of clinical investigators has been brought about by many factors: competing time demands for clinical service, lack of methodologically rigorous training in the disciplines necessary to conduct clinical research, and lack of mentorship. Neurology residents contemplating a clinical research career may observe junior faculty who lack career guidance, are ill-prepared as independent investigators, and must juggle patient demands while trying to write a research grant or conduct a study. Already burdened by medical school debts, is it any wonder that our neurology graduates don't leap to a career with a future that seems so insecure? Academic departments of neurology must develop full-scale clinical research training programs if they are to meet the pressing need for clinical research. As a starting point, they must free themselves from their dependence on providing clinical services to generate income. Following the model which has produced successful basic researchers, much greater effort must be given to establishing rigorous methodological training in collaboration with other departments, creating senior role models, and protecting time for clinical investigators to conduct research. Unless we create incentives to careers in clinical research, we will never answer the growing number of clinical research questions we face today.

Phase III randomized trial of gabapentin in patients with amyotrophic lateral sclerosis.

BACKGROUND: Preclinical and clinical studies of gabapentin in patients with ALS led the authors to undertake a phase III randomized clinical trial. METHODS: Patients were randomly assigned, in a double-blinded fashion, to receive oral gabapentin 3,600 mg or placebo daily for 9 months. The primary outcome measure was the average rate of decline in isometric arm muscle strength for those with two or more evaluations. RESULTS: Two hundred four patients enrolled, 196 had two or more evaluations, and 128 patients completed the study. The mean rate of decline of the arm muscle strength was not significantly different between the groups. Moreover, there was no beneficial effect upon the rate of decline of other secondary measures (vital capacity, survival, ALS functional rating scale, timed walking) nor was there any symptomatic benefit. In fact, analysis of the combined data from the phase II and III trials revealed a significantly more rapid decline of forced vital capacity in patients treated with gabapentin. CONCLUSION: These data provide no evidence of a beneficial effect of gabapentin on disease progression or symptoms in patients with ALS.

US neurologists: attitudes on rationing.

OBJECTIVE: To assess neurologists' attitudes on rationing health care and to determine whether neurologists would set healthcare priorities in ways that are consistent with cost-effectiveness research. BACKGROUND: Cost-effectiveness research can suggest ways to maximize health benefits within fixed budgets but is currently being underused in resource allocation decisions. METHODS: The authors surveyed a random sample of neurologists practicing in the United States (response rate, 44.4%) with three hypothetical scenarios. Two scenarios were designed to address general attitudes on allocating finite resources with emphasis on formulary decisions for costly drugs. The third scenario was designed to assess whether neurologists would optimize the allocation of a fixed budget as recommended by cost-effectiveness analysis. RESULTS: Three-quarters of respondents thought that neurologists make daily decisions that effectively ration healthcare resources, and 60% felt a professional responsibility to consider the financial impact of individualized treatment decisions on other patients. Only 25% of respondents thought that there should be no restrictions placed on any of the five newer antiepileptic agents. In a 1995 survey, 75% of similarly sampled neurologists agreed that no restrictions should be placed on the availability of FDA-approved medications. Nearly half (46%) of respondents favored a less effective test and would be willing to let patients die to ensure the offering of a more equitable alternative. CONCLUSIONS: Most neurologists recognize the need to ration health care, and although they think cost-effectiveness research is one method to achieve efficient distribution of resources, many think that considerable attention should also be given to equity.

Training the future neurology workforce.

OBJECTIVE: To address training demands on future neurologists, the American Academy of Neurology (AAN) surveyed its US members as to their views about training the future neurology workforce. METHODS: The survey was mailed to 575 US neurologists and 425 residents/fellows. Respondents (54%) were asked about their perceptions of current and future educational programs and settings needed to improve practice competence; issues related to subspecialization; and the role of non-neurologists in providing neurologic care. Views of neurologists were compared with those of neurology residents/fellows. RESULTS: Most respondents support additional training in outpatient, community, and staff model health maintenance organization settings. The majority of respondents oppose a required fifth year of training or a yearly competency examination, but neurologists who have a subspecialty interest and residents/fellows favor elective certification and higher fees by subspecialists. General neurologists oppose these ideas. Most neurologists feel that primary care physicians, nurse practitioners, and physician assistants can manage uncomplicated neurologic problems, although residents/fellows are less willing to accept the role of nonphysician providers for neurologic services. CONCLUSIONS: Neurology educational programs should consider addressing deficiencies that today's practitioners perceive. Increasing subspecialization, although favored by most neurologists, creates a challenge for the neurologic community as neurologists without subspecialty training see this trend as a threat to their livelihood.

The ALS patient care database: goals, design, and early results. ALS C.A.R.E. Study Group.

OBJECTIVE: The ALS Patient Care Database was created to improve the quality of care for patients with ALS by 1) providing neurologists with data to evaluate and improve their practices, 2) publishing data on temporal trends in the care of patients with ALS, and 3) developing hypotheses to be tested during formal clinical trials. BACKGROUND: Substantial variations exist in managing ALS, but there has been no North American database to measure outcomes in ALS until now. METHODS: This observational database is open to all neurologists practicing in North America, who are encouraged to enroll both incident and prevalent ALS patients. Longitudinal data are collected at intervals of 3 to 6 months by using standard data collection instruments. Forms are submitted to a central data coordinating center, which mails quarterly reports to participating neurologists. RESULTS: Beginning in September 1996 through November 30, 1998, 1,857 patients were enrolled at 83 clinical sites. On enrollment, patients had a mean age of 58.6 years +/-12.9 (SD) years (range, 20.1 to 95.1 years), 92% were white, and 61% were men. The mean interval between onset of symptoms and diagnosis was 1.2+/-1.6 years (range, 0 to 31.9 years). Riluzole was the most frequently used disease-specific therapy (48%). Physical therapy was the most common nonpharmacologic intervention (45%). The primary caregiver was generally the spouse (77%). Advance directives were in place at the time of death for 70% of 213 enrolled patients who were reported to have died. CONCLUSIONS: The ALS Patient Care Database appears to provide valuable data on physician practices and patient-focused outcomes in ALS.

End-of-life care: a survey of US neurologists' attitudes, behavior, and knowledge.

OBJECTIVE: The American Academy of Neurology (AAN) surveyed the attitudes, behavior, and knowledge of its members regarding care at the end of life. Three groups of AAN members were surveyed: neuro-oncologists, ALS specialists, and a representative sample of US neurologists. METHODS: The survey presented two clinical scenarios involving end-of-life care. Neurologists were asked a series of questions to assess their knowledge of existing medical, ethical, and legal guidelines; their willingness to participate in physician-assisted suicide (PAS) or carry out voluntary euthanasia (VE); and their general attitudes regarding end-of-life care. RESULTS: Neurologists support a patient's right to refuse life-sustaining treatment, but many believe that they are killing their patients in supporting such refusals. Thirty-seven percent think it is illegal to administer analgesics in doses that risk respiratory depression to the point of death. Forty percent believe they should obtain legal counsel when considering stopping life-sustaining treatment. One half believe that PAS should be made explicitly legal by statute for terminally ill patients. Under current law, 13% would participate in PAS and 4% would carry out VE; if those procedures were legalized, 44% would participate in PAS and 28% in VE. Approximately one third believe that physicians have the same ethical duty to honor a terminally ill patient's request for PAS as they do to honor a such a patient's refusal of life-sustaining therapy. CONCLUSIONS: There is a gap between established medical, legal, and ethical guidelines for the care of dying patients and the beliefs and practices of many neurologists, suggesting a need for graduate and postgraduate education programs in the principles and practices of palliative care medicine. Many neurologists would participate in PAS and carry out VE if legalized.

Restoring hand function in patients with severe polyneuropathy: the role of electromyography before tendon transfer surgery.

Electromyography (EMG) was evaluated as a supplement to clinical examination and biomechanical considerations to optimize forearm donor muscle selection before tendon transfers to 4 functionless hands in 3 patients with slowly progressive polyneuropathies. Two patients had unusually severe Charcot-Marie-Tooth disease; the third patient had idiopathic mononeuropathy multiplex. Standard EMG parameters were used to devise an intuitive muscle grading system, including most importantly interference patterns and motor control, plus motor unit morphology and stability. Given our objective of restoring survivable function despite ongoing polyneuropathy, we found that EMG reveals prognostically important differences among partially denervated candidate muscles that cannot be detected by experienced clinical examiners. Opposition transfer was performed on one hand of each patient. After 39-, 39-, and 51-month follow-up durations, restored opposition was graded as good in these 3 hands. We conclude that EMG provides meaningful guidance in selecting optimal forearm muscles for tendon transfers to hands in the setting of slowly progressive polyneuropathies.

Awareness of folic acid for neural tube defect prevention among Israeli women.

The failure of neural tube closure during early embryogenesis results in a range of neural tube defects (NTD), the most common of which is spina bifida. The role of folic acid in reducing the rate of NTD has been well-established. Three recent cases of infants with NTD inspired this investigative study into the level of awareness and knowledge of folic acid and its function in the prevention of NTD among Israeli women. Of 920 women interviewed, only 51 (5.5%) had heard of folic acid, and 27 (2.8%) were reported to have taken it. The source of information and the motivation for self-medication were also explored with regard to socioeconomic and health profile. Awareness of folic acid was significant among women aged 17-29 years (P = 0.005) and those aged 30-39 years (P = 0.009), and among semireligious and nonreligious women (P = 0.008 and 0.01, respectively). Among women who were aware of folic acid, only nonreligious women tended to take it. No correlation was found between folic acid intake and age, religiosity, nationality, number of pregnancies, and health status among women who were aware of folic acid intake. The poor level of awareness, evident in our study, demands that the medical community broadcast the benefit of folic acid. Furthermore, government health initiatives, such as the addition of folic acid to flour preparations, may effectively ensure its appropriate daily intake. These improved education and prevention programs may forcibly reduce the rate of NTD-affected pregnancies.

Measuring quality of care in neurology.

Neurologists are being asked to incorporate methods into daily practice that measure quality of care. Standards of care are increasingly being defined using evidence-based assessments of neurological literature. To evaluate quality of care, a widely accepted and useful model considers the structure, process, and outcomes of care. Outcomes, the impact of care on patients' health, should include measures of mortality, morbidity, disability, patient functioning and well-being (health-related quality of life), and patient satisfaction with care. A variety of private organizations and government programs exist to encourage documentation and promotion of high quality of care. This explosion in quality information is not yet standardized, so that much confusion exists about appropriate data elements to be measured. The challenge is to collect, summarize, and disseminate practical data useful to neurologists and the purchasers and consumers of our services.