Silicon optical fiber.

Described herein are initial experimental details and properties of a silicon core, silica glass-clad optical fiber fabricated using conventional optical fiber draw methods. Such semiconductor core fibers have potential to greatly influence the fields of nonlinear fiber optics, infrared and THz power delivery. More specifically, x-ray diffraction and Raman spectroscopy showed the core to be highly crystalline silicon. The measured propagation losses were 4.3 dB/m at 2.936 microm, which likely are caused by either microcracks in the core arising from the large thermal expansion mismatch with the cladding or to SiO(2) precipitates formed from oxygen dissolved in the silicon melt. Suggestions for enhancing the performance of these semiconductor core fibers are provided. Here we show that lengths of an optical fiber containing a highly crystalline semiconducting core can be produced using scalable fiber fabrication techniques.

Rhythmic auditory stimulation improves gait more than NDT/Bobath training in near-ambulatory patients early poststroke: a single-blind, randomized trial.

OBJECTIVES: The effectiveness of 2 different types of gait training in stroke rehabilitation, rhythmic auditory stimulation (RAS) versus neurodevelopmental therapy (NDT)/Bobath- based training, was compared in 2 groups of hemiparetic stroke patients over a 3-week period of daily training (RAS group, n = 43; NDT/Bobath group =35). METHODS: Mean entry date into the study was 21.3 days poststroke for the RAS group and 22.3 days for the control group. Patients entered the study as soon as they were able to complete 5 stride cycles with handheld assistance. Patients were closely equated by age, gender, and lesion site. Motor function in both groups was pre-assessed by the Barthel Index and the Fugl-Meyer Scales. RESULTS: Pre- to posttest measures showed a significant improvement in the RAS group for velocity (P = .006), stride length (P = .0001), cadence (P = .0001) and symmetry (P = .0049) over the NDT/Bobath group. Effect sizes for RAS over NDT/Bobath training were 13.1 m/min for velocity, 0.18 m for stride length, and 19 steps/min for cadence. CONCLUSIONS: The data show that after 3 weeks of gait training, RAS is an effective therapeutic method to enhance gait training in hemiparetic stroke rehabilitation. Gains were significantly higher for RAS compared to NDT/Bobath training.

Autosomal recessive polycystic kidney disease: radiologic-pathologic correlation.

Autosomal recessive polycystic kidney disease is a heritable but phenotypically variable disorder characterized by varying degrees of nonobstructive renal collecting duct ectasia, hepatic biliary duct ectasia and malformation, and fibrosis of both liver and kidneys. In the kidney, the dilated collecting ducts and interstitial fibrosis, when severe, may significantly impair renal function and result in hypertension and renal failure. Imaging typically shows large but reniform kidneys, diffusely increased renal parenchymal echogenicity at ultrasonography, and a striated nephrogram after contrast material administration. In the liver, periportal fibrosis accompanies the malformed and dilated bile ducts; this may result in portal hypertension. The liver may appear normal or may show intrahepatic biliary dilatation; once portal hypertension develops, splenomegaly and varices are usually evident. The relative degrees of kidney and liver involvement tend to be inverse: Children with severe renal disease usually have milder hepatic disease, and those with severe hepatic disease tend to evidence mild renal impairment. Presently, treatment consists of supportive management and control of hypertension. Replacement therapy for renal failure (dialysis or kidney transplantation) and control of portal hypertension (portal circulatory diversion or liver transplantation) may be necessary.

Rhythmic facilitation of gait training in hemiparetic stroke rehabilitation.

Experimental and control groups of 10 hemiparetic stroke patients each underwent a 6 week, twice daily gait training program. The control group participated in a conventional physical therapy gait program. The experimental group trained in the same basic program with the addition of rhythmic auditory stimulation (RAS). Patients entered the study as soon as they could complete 5 strides with hand-held assistance. The training program had to be completed within 3 months of the patients' stroke. In the experimental group RAS was used as a timekeeper to synchronize step patterns and gradually entrain higher stride frequencies. Study groups were equated by gender, lesion site, and age. Motor function was assessed at pretest using Barthel, Fugl-Meyer, and Berg Scales. Walking patterns were assessed during pre- and post-test without RAS present. Pre- vs post-test measures revealed a statistically significant (P<0.05) increase in velocity (164% vs 107%), stride length (88% vs 34%), and reduction in EMG amplitude variability of the gastrocnemius muscle (69% vs 33%) for the RAS-training group compared to the control group. The difference in stride symmetry improvement (32% in the RAS-group vs 16% in the control group) was statistically not significant. The data offer evidence that RAS is an efficient tool to enhance efforts in gait rehabilitation with acute stroke patients.

Rhythmic auditory-motor facilitation of gait patterns in patients with Parkinson's disease.

OBJECTIVES: The effect of rhythmic auditory stimulation (RAS) on gait velocity, cadence, stride length, and symmetry was studied in 31 patients with idiopathic Parkinson's disease, 21 of them on (ON) and 10 off medication (OFF), and 10 healthy elderly subjects. METHOD: Patients walked under four conditions: (1) their own maximal speed without external rhythm; (2) with the RAS beat frequency matching the baseline cadence; (3) with RAS 10% faster than the baseline cadence; (4) without rhythm to check for carry over from RAS. Gait data were recorded via a computerised foot switch system. The RAS was delivered via a 50 ms square wave tone embedded in instrumental music (Renaissance style) in 2/4 metre prerecorded digitally on a sequencer for variable tempo reproduction. Patients on medication were tested in the morning 60-90 minutes after medication. Patients off medication were tested at the same time of day 24 hours after the last dose. Healthy elderly subjects were tested during the same time of day. RESULTS: Faster RAS produced significant improvement (P < 0.05) in mean gait velocity, cadence, and stride length in all groups. Close synchronisation between rhythm and step frequency in the controls and both Parkinson's disease groups suggest evidence for rhythmic entrainment mechanisms even in the presence of basal ganglia dysfunction. CONCLUSIONS: The results are consistent with and extend prior reports of rhythmic auditory facilitation in Parkinson's disease gait when there is mild to moderate impairment, and suggest a technique for gait rehabilitation in Parkinson's disease.

Rhythmic auditory stimulation in gait training for Parkinson's disease patients.

Rhythmic auditory stimulation (RAS) was used as a pacemaker during a 3-week home-based gait-training program for Parkinson's disease (PD) patients (n = 15). Electromyogram (EMG) patterns and stride parameters were assessed before and after the test without RAS to evaluate changes in gait patterns. Data were compared with those of two control groups (n = 11), who either did not participate in any gait training or who participated in an internally self-paced training program. RAS consisted of audiotapes with metronome-pulse patterns embedded into the on/off beat structure of rhythmically accentuated instrumental music. Patients who trained with RAS significantly (p < 0.05) improved their gait velocity by 25%, stride length by 12%, and step cadence by 10% more than self-paced subjects who improved their velocity by 7% and no-training subjects whose velocity decreased by 7%. In the RAS-group, timing of EMG patterns changed significantly (p < 0.05) in the anterior tibialis and vastus lateralis muscles. Evidence for rhythmic entrainment of gait patterns was shown by the ability of the RAS group to reproduce the speed of the last training tape within a 2% margin of error without RAS.

Components of EMG symmetry and variability in parkinsonian and healthy elderly gait.

Variability and bilateral symmetry of EMG gait-cycle profiles were studied in parkinsonian and healthy elderly subjects in the gastrocnemius, tibialis anterior, and vastus lateralis muscles. Components reflecting shape and timing were defined by the magnitude and phase of the cross-correlation function between individual stride profiles and the latency corrected ensemble average (LCEA) (variability), and between bilateral LCEAs (symmetry). Statistical significance was set at a confidence level of 0.01 reflecting a Bonferroni adjustment due to multiple measures. Parkinsonian gait was significantly different from the healthy elderly in several measures: increased shape variability and asymmetry in the gastrocnemius and tibialis anterior muscles, and reduced timing variability in the gastrocnemius. A portion of the parkinsonian group participated in a 3 week therapy program where they walked to rhythmic auditory stimulation. Gait parameters shifted toward healthy elderly values in each measure where population differences were found. Significant changes were observed in decreased tibialis anterior shape variability and asymmetry, and gastrocnemius shape variability. Strong trends were also observed in increased gastrocnemius timing variability and reduced bilateral asymmetry. In addition to the expected decreased in variability and asymmetry of healthy elderly, increased timing variability in the gastrocnemius was associated with a more normal gait, possibly reflecting feedback adaptability of muscle activity which may be useful in generating stable locomotion.

Neuropsychological performance and CD4 levels in HIV-1 asymptomatic infection.

The performance of 68 HIV-1 seropositive asymptomatic (HIV+) subjects stratified on CD4 levels were compared with 82 HIV-1 seronegative (HIV-) subjects on a battery of neuropsychological, mood state, and perceived health status measures. The neuropsychological test battery included measures of attention, reaction time, memory, intellectual ability, psychomotor speed, frontal lobe or "executive" function, and decision time. None of the HIV+ subjects were taking antiviral agents. The groups did not differ for age, mood state, or WAIS-R Verbal and Performance IQ scores. Due to group differences for education and weekly ethanol consumption, both variables were used as covariates in multivariate analyses of variance. Relatively few differences were observed between subgroups of HIV+ patients or between these subgroups and control subjects. These data suggest that factors other than absolute levels of immunosuppression as expressed by CD4 levels alone, appear to be responsible for the deficits observed in HIV+ asymptomatic patients.

The influence of age on endocrine responses to ultraendurance stress.

BACKGROUND: Aging produces significant changes in the human endocrine system. This study was designed to determine if elderly and younger individuals differ in various endocrine measures before and after ultraendurance stress. METHODS: Sixteen young and 19 older subjects competing in a world championship triathlon had blood samples acquired for 13 hormones before, immediately after the event, and 18 hours into recovery. RESULTS: Following the triathlon, almost every hormone level increased. Significantly higher basal circulating levels of dihydroepiandrosterone sulfate (DHEA-S) and thyroid stimulating hormone (TSH) were found in 20-year-old individuals, whereas higher levels of norepinephrine (NEPI) and sex hormone binding globulin (SHBG) were found in the 50- to 74-year-old group. Older subjects had lower postexercise levels of EPI, DHEA-S, GH, and PRL and higher postexercise levels of estradiol than younger individuals. Similarity in pre- and postrace weights as well as Hgb and Hct levels suggested that dehydration, while present, did not significantly contribute to the endocrine changes. CONCLUSIONS: Ultraendurance stress produced dramatic increases in all but one of the hormones evaluated. Whether frequent exercise can alter the endocrine changes that occur with aging cannot be answered by this study. It is clear, however, that when comparisons are made with young active individuals, frequent exercise does not eliminate the differences in basal concentrations of TSH, DHEA-S, SHBG, and NEPI or exercise-induced release of estradiol, GH, and PRL that occur with aging.

Psychopathology in human immunodeficiency virus infection: lifetime and current assessment.

The present study determined lifetime and current psychiatric functioning in a sample of homosexual or bisexual men at various stages of human immunodeficiency virus (HIV) infection in order to address several questions regarding the relationship between psychopathology and HIV infection. HIV+ asymptomatic or symptomatic and HIV- homosexual or bisexual men completed self-report measures of psychological and health functioning and participated in structured diagnostic interviews. Additional information regarding HIV-related life events and their potential relationship to onset of disorder and family history of psychiatric disorder were obtained. A high lifetime prevalence of affective and substance use disorder was found, with almost one half of the sample meeting criteria for both disorders. Lifetime affective disorder diagnosis was associated with a positive family history of affective disorder. HIV-related events were most closely associated with onset or recurrence of affective disorder compared with other disorders. Low current rates of psychiatric disorder and levels of emotional distress were found, with no differences in degree of psychiatric adjustment across stage of infection. We conclude that the lifetime prevalence of certain categories of psychiatric disorder is high in both HIV+ and HIV- homosexual samples. Increased rates of psychiatric disorders do not appear to be a consequence of HIV infection. However, episodes of illness, particularly affective disorder, may develop following an HIV-related event such as confirmation of infection. Although symptomatic subjects have more somatic difficulties, there appears to be no relationship between stage of illness and level of emotional distress.

Lack of significant changes in nutrition-related parameters with tumor necrosis factor treatment of cancer.

Cancer and its therapies frequently produce anorexia and cachexia. In this study, the acute (3 days) and chronic (4 wks) nutrition-related effects of cancer therapy with recombinant human tumor necrosis factor (rHuTNF) were investigated and described. Nutritional status, as measured by body weight and body composition (body fat and lean-to-fat ratio) with use of bioelectrical impedance, did not appear to deteriorate. None of the serum lipids changed significantly, but triglycerides did rise modestly over four weeks of therapy. Glucose and the peptide hormones (insulin, C-peptide, glucagon, and pancreatic polypeptide) thought to affect appetite did not change with rHuTNF therapy. Therefore, although TNF is thought to contribute to wasting in animal models, it had no negative effect on nutritional status in our small sample. The lack of adverse effect noted in this study is possibly due to the low dose level of rHuTNF or to adaptation.

Rate of CD4 decline and neuropsychological performance in HIV infection.

This study examined the relationship between performance on a battery of neuropsychologic tasks and rate of CD4 lymphocyte decline in 47 gay or bisexual men infected with the human immunodeficiency virus type 1. Subjects were volunteers for a longitudinal study of the human immunodeficiency virus infection and were not selected because of neuropsychiatric symptoms. Subjects were at all stages of illness, although most were asymptomatic. Faster rates of decline in percent CD4 lymphocyte were related to poorer performance on measures of memory and reaction time. This relationship was independent of stage of illness and CD4 level at the time of neuropsychologic examination, and was not due to medication effects. The rate of percent CD4 lymphocyte cell loss is associated with and may represent a risk factor for the development of the human immunodeficiency virus-related neurobehavioral deficit.

The effect of exercise training on body weight and peptide hormone patterns in normal weight college-age men.

Resting and peak glucose, insulin, glucagon, gastric inhibitory polypeptide (GIP) and pancreatic polypeptide (PP) levels were evaluated pretraining, 3 weeks and 10 weeks posttraining in seven college age males. The exercise consisted of thrice weekly session of jogging at 70% VO2max for 20 minutes plus warmup and cool down. Following the 10 weeks, VO2max increased significantly. Body weight remained constant and body fat decreased significantly. Fasting and peak blood glucose levels were normal at the beginning of the study yet improved with training. As expected, fasting and peak insulin levels decreased significantly with training. Although GIP did not change significantly with training, an uncoupling of GIP and insulin peak responses was observed. Glucagon levels were essentially unchanged. Fasting and peak PP levels increased slightly as training occurred. These hormone responses suggest that perhaps body weight and/or changes in body fat stores and fuel use might influence peptide hormone responses with training.

Analysis of EMG activity and temporal components of gait during recovery from perturbation.

In ten able-bodied adults, gait was unexpectedly displaced in order to induce rapid dorsiflexion at heelstrike. Electromyographic (EMG) data were collected bilaterally from the tibialis anterior (TA) and gastrocnemius (G) muscles, and electrogoniometric data monitored joint angle changes in the ankle. Analysis of the data indicated initial EMG responses in the G of the perturbed limb and the TA of the contralateral limb at latencies of approximately 100 msec. It appeared that G activity served to decelerate the dorsiflexion of the ankle of the perturbed limb, whereas the TA accelerated dorsiflexion in the swing limb. Analysis of later EMG activity and foot-ground contact indicated that recovery after perturbation was easily completed during stance of the perturbed limb. Because of the comparatively minimal degree and velocity of displacement, further study with similar protocols might be considered appropriate to study balance problems in clinical populations.

The response of serum growth hormone and prolactin to training in weight-maintaining healthy males.

Resting levels of serum growth hormone (GH) and prolactin (PRL) were measured pretraining, 3 weeks and 10 weeks posttraining in seven college age males. The exercise consisted of thrice weekly sessions at 70% VO2max for 20 minutes plus warmup and cool down. Body weight remained constant during the ten week training period. However, body fat decreased significantly. Resting daytime levels of GH decreased significantly with training while resting PRL levels were unchanged. The hormone responses suggest attenuation of resting GH levels with training and may relate to changes in body fat.

A brief scale for the dementia of Parkinson's disease.

The lack of standardized criteria and methodologies to assess dementia in patients with Parkinson's disease has resulted in inconsistencies and controversies in the literature regarding the incidence and basis of this condition. The authors examined a large group of patients with Parkinson's disease using two standardized sets of criteria for dementia. The neuropsychological data obtained was analyzed using stepwise discriminant analysis, and a brief scale was developed. The results indicated that a regression equation derived from just three neuropsychological procedures (which take only 10 minutes to administer) provides maximum discrimination between patients originally classified as demented or non-demented according to standardized criteria. Cut-off values for the product of the regression equation were calculated to accurately and reliably classify patients using the brief scale.

Surgical management of pancreatic lymphoma.

The clinical and pathologic records of 12 patients with pancreatic lymphoma were reviewed retrospectively to determine distinguishing clinical features. Radiologically, all patients had large abdominal masses in the region of the pancreas. Preoperative percutaneous cytologic biopsy specimens failed to make the diagnosis, and two specimens were interpreted incorrectly as poorly differentiated adenocarcinoma. The diagnosis was difficult to make in two cases, even at laparotomy. Four patients underwent a biliary bypass, and two underwent a concomitant gastric or duodenal bypass. Two patients died postoperatively. Four patients responded well to chemotherapy and/or radiation therapy, and two did not have any recurrences at 3 and 7 years postoperatively. Although rare, lymphoma should be considered in patients with undiagnosed pancreatic masses. The diagnosis may only be made with appropriate preoperative or intraoperative suspicion, and treatment may be rewarding, particularly in comparison with pancreatic adenocarcinoma.

Weight change and peptide hormone responses in patients receiving interferon.

The purpose of this pilot study was to describe body weight status and peptide hormone responses in patients receiving interferon (IFN) therapy for renal cell carcinoma. Eighteen patients were on therapy for approximately two to three months. Mean weight loss of the patients was 2.2 +/- 0.9 kg (mean +/- SEM) or 4.9 +/- 0.9% of prestudy weight. Of the 18 patients, 6 were further evaluated for peptide hormone responses to meal stimulation before and after treatment (mean: 1.5 months). These subjects had a mean weight loss of 4.3 +/- 1.6 kg or 7.0 +/- 3.5% of prestudy weight. Blood was drawn from subjects before and six times after they had consumed a defined formula liquid meal to provoke enteroinsular peptide release. It was discovered that one-half of this group (n = 3; Group A) had some glucose intolerance following IFN therapy, despite increased response of insulin, gastric inhibitory polypeptide (GIP), and pancreatic polypeptide (PP) to meal stimulation. Further, patients in Group A had a weight loss of -11.7 +/- 2.7% of prestudy weight, whereas the other three patients (Group B) experienced a mean loss of -2.3 +/- 1.2% (p less than 0.04). The three subjects characterized by the smaller loss of prestudy weight (Group B) had decreased glucose response to meal stimulation, despite decreased responses of insulin and GIP. Response of PP was slightly increased with treatment in group B, but the increase was not as large as that in Group A. These data may suggest that extreme weight loss and altered peptide hormone response occur in a subset of cancer patients receiving interferon therapy.

Compact linear array external cavity laser.

Successful operation of a compact linear array external cavity laser exhibiting wavelength control of five (widely spaced) individual diode elements and phase-locked operation was demonstrated. The locked array output was tunable over a 15-nm range.