Age-matched Normal Subjects Research Articles

Morphological algebraic models of the TU-wave patterns/in idiopathic long QT syndrome

A computer-assisted analysis of the TU-complex morphology was employed to characterize repolarization abnormalities in LQTS and to assess arrhythmic risk. Electrocardiograms (ECGs) were collected from 14 idiopathic LQTS patients (seven without symptoms and seven with a history of syncope or cardiac arrest) and from 14 sex- and age-matched normal subjects. Digitized TU-wave patterns from V2–V6 precordial leads were analyzed. The morphologies of the T and U waves were modeled by an algebraic sum of differences between two pairs of action potential-like curves of different shape and duration so that the whole TU complex was approximated by (S1−S2)+(L1−L2). By finding the best fit model of the digitized TU-wave signal, the amplitude and duration of each decomposition curve were determined for each lead. The following ‘secondary’ parameters were then derived: (a) the ratio between the sum of the amplitudes of the two long (L1 and L2) and the two short (S1 and S2) decomposition curves (A-ratio), (b) the highest A-ratio found in V2 to V6 (A-ratio max), and (c) the model-derived durations of the T-wave, U-wave and TU-complex. Conventional measures of RR and QTc intervals and of QT dispersion did not differ between symptomatic and asymptomatic LQTS patients. Modeled QT interval was significantly longer in the symptomatic than in the asymptomatic LQTS patients and in asymptomatic LQTS patients than in the controls. In addition, symptomatic LQTS patients had a longer S2 and T-wave duration in most leads than normal subjects. Conversely, modeled QU interval and U-wave duration did not significantly differ between the three groups. Compared to normal subjects, the amplitudes of S1, S2, L1 and L2 in the LQTS patients were not significantly different in most leads. A-ratio and A-ratio max were greater in symptomatic than asymptomatic LQTS patients and in the latter than in controls. A cut-off value of 0.90 of A-ratio max separated all symptomatic (1.34±0.38) from all asymptomatic patients (0.60±0.21). Although the correlation between model parameters and cellular substrate is at present unclear, it is possible that the morphological alterations described by the model are related to the arrhythmogenic mechanism(s) of the idiopathic LQTS.

18F]FDG-PET study in dementia with lewy bodies and alzheimer's disease

1. The authors report two siblings with dementia with Lewy bodies (DLB). Both the older brother and the younger sister underwent positron emission tomography (PET) studies with [ 18F]-2-fluoro-deoxy-D-glucose (FDG) during life. The FDG-PET study demonstrated unique and pronounced metabolic impairment in the occipital cortex in both patients. The clinical diagnosis of DLB in the sister was confirmed by autopsy. 2. FDG-PET images from 11 patients with Alzheimer's disease (AD), 7 patients with DLB and 10 age-matched normal subjects were obtained and analyzed by the statistical parametric mapping (SPM) method. The SPM demonstrated a widespread metabolic reduction in the DLB group. The reduction was particularly pronounced in the visual association cortex in the DLB group compared to the AD group irrespective of clinical severity of the disease. 3. These findings suggest that functional neuroimaging techniques, including FDG-PET, will provide a valuable diagnostic aid to differentiate DLB from AD, and this will help detect DLB patients in the early stage of the disease. Alzheimer's disease (AD), consortium on dementia with Lewy bodies (CDLB), dementia with Lewy bodies (DLB), [ 18F]-2-fluoro-deoxy-D-glucose (FDG), Lewy bodies (LBs), positron emission tomography (PET), statistical parametric mapping (SPM)

Cytoplasmic Transfer of Platelet mtDNA from Elderly Patients with Parkinson's Disease to mtDNA-less HeLa Cells Restores Complete Mitochondrial Respiratory Function

For determination of whether platelet mtDNA in patients with Parkinson's disease (PD) possesses some lesions to reduce respiratory enzyme activities, platelet mtDNA was transferred into mtDNA-less (ρ0) HeLa cells from aged PD patients and age-matched normal subjects, since their activities were controlled by both mitochondrial and nuclear genomes. The resultant mtDNA-repopulated cybrid clones containing the HeLa nuclear genome as a common background were used for comparison of respiratory enzyme activities. Remarkable variations of the enzyme activities were observed in the cybrid clones, irrespective of whether their mtDNA was transferred from normal subjects or PD patients, and some of them showed 20% reduction of average activities. Thus, the mtDNA mutations responsible for inducing 20% reduction should be polymorphic rather than pathogenic. On the other hand, pathogenic control cybrid clones possessing mtDNA mutations from patients with mitochondrial disorders showed significant and specific decline of respiratory enzyme complex I activity beyond the normal range of the variations. These observations warrant reassessment of the conventional concept that complex I activity in platelets of PD patients is defective due to mtDNA mutations.

ACTIGRAPHIC SLEEP-WAKE PATTERNS AND URINARY 6-SULFATOXYMELATONIN EXCRETION IN PATIENTS WITH ALZHEIMER'S DISEASE

Recent studies suggest melatonin, due to its antioxidant and free-radical- scavenging actions, may play a role in the neuroprotection against amyloid, which is implicated in the pathogenesis of Alzheimer's disease (AD). In this study, we determined urinary 6-sulfatoxymelatonin (aMT6s) excretion together with actigraphic sleep-wake patterns of untreated male patients with AD who lived at home. Results were compared with those obtained from normal age-matched elderly and normal young male subjects. Similar measurements were also performed in another group of patients with AD who were treated with a cholinesterase inhibitor (Donepezil, Aricept). Total 24h aMT6s values were significantly reduced in elderly controls (19.9h ± 5.2 μg/24h), in those with untreated AD (12.7 ± 4.4 μg/24h), and in patients treated for AD (12.4 ± 4.4 μ g/24h) compared with normal young men (32.8 ± 3.1 μ g/24h). A day-night difference in aMT6s was evident in all young controls, in 50% of elderly controls, in only 20% of patients with untreated AD, and in 67% of those with AD receiving Aricept. Sleep quality (expressed as sleep efficiency, wake time, and long undisturbed sleep duration) was better in young and elderly controls compared with the two groups of patients with AD. There was no significant correlation between aMT6s values or sleep patterns and the severity of cognitive impairment in patients with AD. Taken together, these data suggest that disrupted sleep, decreased melatonin production, and partial lack of day-night difference in melatonin secretion were observed equally in normal elderly and in patients with AD. Our results do not permit drawing any conclusion as to whether changes in urinary aMT6s excretion is correlated with disturbed sleep in patients with AD. (Chronobiology International, 18(3), 513–524, 2001)

Do P1 and N1 evoked by the ERP task reflect primary visual processing in Parkinson's disease?

To evaluate whether P1 and N1 evoked by ERP tasks could appropriately reflect primary visual processing in Parkinson's disease (PD). We recorded ERPs in 13 PD patients with duration of illness less than 5 years and 18 age-matched normal control subjects. P1 and N1 from Oz were evoked by a visual oddball and a delayed matching S1-S2 task. The effect of different events on P1 and N1 was studied. All patients were given an ECD-SPECT examination, and the SPECT images were overlaid on the 3D-MRI. The correlation of P1 or N1 to the regional cerebral blood flow (rCBF) was studied. P1 was not influenced by different events. There was no significant P1 differences between the PD and the normal group. N1 was significantly shorter and smaller in the patients than that in the normal group. N1 amplitude after the waveform subtraction (target-frequent) in the PD group did not show significant difference with that in the normal controls, nor with the N1 before the subtraction. Nd, the subcomponent of N1 after the subtraction in the patients was significantly earlier and smaller than that in the normal controls. P1 only weakly correlated with the rCBF in the occipital lobe. N1 was correlated with the rCBF in a global region. The results provided some evidence that P1 might reflect the primary visual processing, and N1 might be involved in both primary and cognitive visual processing. The altered N1 in the PD patients might be due to the deformed Nd.

Non-invasive diagnosis of concealed Wolff-Parkinson-White syndrome by detection of concealed anterograde pre-excitation.

Electrophysiological findings suggest that concealed anterograde conduction through accessory pathways may exist even during sinus rhythm in patients with so-called concealed Wolff-Parkinson-White (WPW) syndrome. To evaluate the pre-excitation characteristics in various types of WPW syndrome, high-resolution electrocardiograms were analyzed in 81 consecutive WPW syndrome patients and 50 age-matched normal subjects. The WPW group consisted of 30 cases of concealed WPW diagnosed by electrophysiological study, 38 cases of manifest WPW in which apparent delta waves were constant, and 13 cases of intermittent WPW in which the delta waves appeared periodically. The duration of the low-amplitude, high-frequency components of the signal-averaged filtered QRS complex that preceded the earliest upstroke of the surface QRS, including any delta waves (preceding potential duration, PPD), and the duration of low amplitude signals less than 10 microV (I-LAS10) or 20 microV (I-LAS20) were measured as parameters of pre-excitation. The PPDs in concealed and intermittent WPW were both significantly longer than in manifest WPW or in control subjects (6.8+/-2.7 ms, 7.9+/-3.5 ms vs 2.3+/-3.2 ms, 1.0+/-1.6 ms, both p<0.0001). Abnormally prolonged PPDs (>4 ms) were observed in 90% of concealed WPW cases and 76.9% of intermittent WPW, but in only 4% of normal subjects and 31.6% of manifest WPW. Both I-LAS10 and I-LAS20 in the 3 types of WPW syndrome were significantly longer than in normal subjects. The initial portion of the filtered QRS in concealed WPW closely resembled that of intermittent WPW. These results strongly suggest that in concealed WPW anterograde conduction through accessory pathways does occur and produces small amounts of pre-excitation even during sinus rhythm. The study concluded that, despite its name, concealed WPW is not completely concealed, and that non-invasive diagnosis during sinus rhythm is possible by using high-resolution electrocardiography to detect the concealed anterograde pre-excitation.

Defective Representation of Knowledge in Parkinson's Disease: Evidence from a Script-Production Task

The deficits seen in frontal-lobe patients and in the elderly show clearly that spontaneous script generation depends on good frontal-lobe function. Shallice, however, has proposed that one aspect of script generation (contention scheduling, CS) which is involved in the activation and maintenance of overlearned or routine scripts may depend more on the basal ganglia. Patients with Parkinson's disease would thus be expected to manifest deficits somewhat different from those observed in frontal-lobe patients when generating scripts. The performances of 16 nondemented and nondepressed patients with idiopathic Parkinson's disease were compared to those of 16 age-matched normal control subjects under two experimental conditions; routine, forward script generation and nonroutine, backward script generation. Parkinsonian patients generated scripts significantly deprived of contextual elements in the forward condition and made significantly more sequencing and perseverative errors in both forward and backward conditions than did normal subjects. They also produced a significantly higher number of irrelevant intrusions, in both conditions, than did controls. These results support, in a general sense, Shallice's notion that the basal ganglia are important in script generation; however, other specific predictions of Shallice's model were not supported by our findings.

Central Corneal Thickness of Normal Tension Glaucoma Patients in Japan

Purpose: To compare central corneal thickness (CCT) of patients with normal tension glaucoma (NTG) with that of age-matched normal subjects, patients with open-angle glaucoma (POAG) and ocular hypertension (OH) subjects in Japan. Methods: Central corneal thickness was measured in 79 NTG, 61 POAG, 73 OH, and 50 normal subjects with an ultrasonic pachymeter. One eye for 1 subject randomly selected in each group was used for inter-group comparison. The relationship between CCT and the maximum intraocular pressure (IOP) measured by Goldmann applanation tonometer with no ocular hypotensive medication (NTG, OH, and normal subjects) or under medication (POAG patients) was analyzed. Results: The CCT of OH subjects (582 ± 32 μm; mean ± SD) was significantly greater than that of the other groups ( P < .001), while no difference was seen in CCT among normal (552 ± 36 μm), NTG (548 ± 33 μm) and POAG (550 ± 33 μm) subjects. In normal subjects, CCT and the maximum IOP were significantly correlated but the correlation coefficient was small ( r = 0.420, P < .05). Conclusions: Central corneal thickness shows no significant difference among NTG, POAG, and normal subjects in Japan, while it is significantly greater in OH subjects. The CCT has little influence on the diagnosis of NTG in Japan.

Quantitative assessment of ventricular function in children with single ventricles using the Doppler myocardial performance index

Assessment of ventricular function in patients with functionally single ventricles and unusual ventricular geometry is difficult. The Doppler myocardial performance index (MPI) may provide a method of assessing function in these patients. The purposes of this study were to compare the MPI in normal children and in children with a functionally single ventricle, and to compare the MPI in patients with single ventricles before and after bidirectional cavopulmonary anastamosis (BCPA). Echocardiograms of all patients who underwent BCPA between January 1994 and December 1998 were reviewed before and after surgical palliation. Age-matched normal subjects (n = 30) served as controls. The MPI was calculated from Doppler tracings of ventricular inflow and outflow. Of the 60 patients with single ventricles who underwent BCPA, 41 had adequate preoperative Doppler studies to allow calculation of the MPI, and 21 of 41 had adequate studies before and after BCPA. The MPI was higher in patients with single ventricles than in normal controls (0.67 ± 0.14 vs 0.32 ± 0.10, p <0.001). There was no significant difference in the MPI in patients with single ventricles before and after surgery (0.70 ± 0.16 vs 0.66 ± 0.15). However, patients who had a BCPA at <1 year of age had a significant decrease in the MPI after surgery (0.71 ± 0.10 vs 0.61 ± 0.11, p = 0.01). Compared with controls, the MPI was significantly higher in patients with single ventricles suggesting an altered hemodynamic state consistent with decreased ventricular function. The MPI decreased in patients who underwent BCPA at <1 year of age, suggesting an improvement in ventricular function. The MPI provides an objective method of assessing and following ventricular function in patients with single ventricles that is independent of ventricular geometry.

Nerve fiber analyzer and short-wavelength automated perimetry in glaucoma suspects: A pilot study

Purpose To test the relationship between the results of short-wavelength automatic perimetry (SWAP) and retinal nerve fiber layer (RNFL) measurements with scanning laser polarimetry (Nerve Fiber Analyzer, NFA) in age-matched normal subjects, glaucoma suspects, and early glaucoma patients. Design Case-control study. Participants and methods Thirty-eight normal subjects, 32 glaucoma suspects, and 14 early glaucoma patients were recruited. All subjects underwent RNFL assessment by NFA, achromatic visual field testing (24-2 threshold), and repeated SWAP (24-2 threshold blue-on-yellow). Main outcome measures Mean deviation (MD) of visual field testing and RNFL values were obtained. Results Glaucoma suspects were divided into two groups according to their SWAP results: high risk (with SWAP abnormalities) and low risk (with normal SWAP result). No statistically significant difference in SWAP MD and RNFL values were observed between normal and low-risk groups ( P > 0.05), but these values were found to be significantly lower in high-risk and early glaucoma groups ( P < 0.01). Conclusions This study suggests that RNFL examination by NFA may be a useful test for the early detection of glaucomatous damage of glaucoma suspects. It appears to provide agreement with SWAP abnormalities and is more sensitive than conventional standard automated perimetry.

Apparent diffusion coefficient measurements in progressive supranuclear palsy.

We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes.

Abnormal premovement gating of somatosensory input in writer's cramp

One characteristic of focal dystonia is the sensory trick, by which sensory input to a certain area of the body can reduce abnormal contractions in muscles nearby. This suggests that adjusting the link between sensory input and movement allows motor commands to be issued more effectively from the brain. To explore this sensorimotor link, we studied the attenuation (gating) of somatosensory evoked potentials (SEPs) before and during hand movements in patients with writer's cramp. For premovement gating, 10 patients and 11 age-matched normal subjects were given a warning sound followed 1s later by an electric stimulus to the right median nerve at the wrist. The latter served both as a reaction signal to start a finger extension task and as the input to evoke SEPs over the scalp. Because reaction times always exceeded 70 ms, short-latency SEPs thus obtained were unaffected by the afferents activated by the movement. The amplitudes of frontal N30 components were significantly decreased over the frontal leads compared with SEPs elicited at rest (P: < 0.002) in the normal group, whereas significant gating was found not for N30 but for frontal P22 (P: = 0. 002) in the patient group. For midmovement gating studies, SEPs to the right median nerve stimulation were recorded in 16 patients and 12 age-matched normal subjects at rest, and during active and passive finger extension-flexion movements. In contrast to the premovement SEPs, the frontal N30 was equally gated during active and passive movements both in the patient (P: < or = 0.002) and the normal group (P: < or = 0.003). These findings indicate that in writer's cramp the sensitivity of sensory input channels from the hand is wrongly set by the central command to move. Perhaps the sensory trick, by supplying additional input not usually present during unobstructed movement, is a manoeuvre to correct this imbalance. Dystonia may result not only from abnormalities in the central motor command but also from disturbed central processing of sensory input.

Evaluation of postural stability in elderly with diabetic neuropathy.

The objective of this study was to compare clinical and biomechanical characteristics of balance in diabetic polyneuropathic elderly patients and normal age-matched subjects. Fifteen elderly with distal neuropathy (DNP) and 15 healthy age-matched subjects were evaluated with the biomechanical variable COP-COM, which represents the distance between the center of pressure (COP) and the center of mass (COM). Measurements were taken in the quiet position with a double-leg stance, in eyes-open (EO) and eyes-closed (EC) conditions. Subjects were also assessed with clinical balance evaluations. The COP-COM variable was statistically significantly larger in the DNP group than in the healthy group in anterior-posterior (A/P) and medial-lateral (M/L) directions. Furthermore, the DNP group showed statistically significantly larger amplitudes of the COP-COM variable without vision. The severity of the neuropathy, as quantified using the Valk scoring system, was correlated with COP-COM amplitude in both directions. Evaluation of the postural stability of an elderly diabetic population using the COP-COM variable can detect a very small change in postural stability and could be helpful in identifying elderly with DNP at risk of falling.

Carotid Doppler high-intensity transient signals in dilated cardiomyopathy

Background Thromboembolism is an infrequent but serious complication in dilated cardiomyopathy (DCM), and the role of primary preventive antithrombotic or anticoagulation therapy is undetermined. High-intensity transient signals (HITS) by Doppler ultrasound representing microemboli have been described in various clinical settings associated with increased risk of stroke. This study assessed the feasibility, reproducibility, and prevalence of HITS in patients with DCM. Methods Thirty patients with severely reduced left ventricular ejection fraction (≤35%, mean 25%) and New York Heart Association class II to III who were not receiving antithrombotic or anticoagulant therapy and 20 age-matched normal subjects were prospectively examined. Patients with atrial fibrillation, significant cardiac valvular heart disease, a history of cerebrovascular disease, and those who otherwise required antithrombotic or anticoagulation therapy were excluded. One-hour pulsed-wave Doppler recordings over the common carotid artery (CCA) were performed on 3 separate days in each subject by a single, experienced, blinded sonographer with a 4-MHz probe (TC-2000, Nicolet/EME) with a specially designed probe holder. Studies were read in a blinded, random fashion by 2 independent, experienced HITS Doppler recording readers. Results HITS in the CCA were detected in 6 (20%) of 30 patients with DCM and in 3 (15%) of 20 volunteers. This difference was not statistically significant. Intrareader and interreader reproducibility were high (κ = 0.91 and 0.84, respectively; P <.001), whereas intrasubject reproducibility over the 3 visits was moderate to low (κ = 0.22). There was no significant difference between HITS characteristics, that is, intensity and duration, in patients versus controls. Conclusions The prevalence of CCA HITS in patients with clinically stable heart failure who are not receiving anticoagulation/antithrombotic therapy and are not in atrial fibrillation is low and not significantly different from normal patients. These data suggest that HITS monitoring is not a viable surrogate marker for increased thromboembolic risk in such patients with DCM. (Am Heart J 2000;140:e4.)

Abnormal information processing in dementia of Alzheimer type. A study using the event-related potential's field.

Electrical field changes of event-related potentials (ERPs) were investigated in 26 patients with dementia of Alzheimer's type (DAT) and 12 age-matched normal subjects. The patients were assessed with the Clinical Dementia Rating and Mini-Mental State. Each patient selected had only mild to moderate mental disability. Auditory oddball stimulation was presented at 1.5 s intervals and 1,000 Hz for the nontarget and 2,000 Hz for the target tones, both at 85 dB. The target tones were 20% of all the tones. The reference-independent data (latency, global field power: GFP, dissimilarity index: DISS and location of centroids) were obtained and analyzed for each ERP component. The momentary electric strength or 'hilliness' of the ERPs landscape was indicated by GFP. The patients showed prolonged latencies and decreased P300 GFP amplitudes and of N100 GFP. These findings suggest that the abnormal electrical field of ERP may reflect abnormal information processing following the attentional process for target stimuli in DAT patients.

Near-maximal fractional oxygen extraction by active skeletal muscle in patients with chronic heart failure.

Systemic oxygen uptake and deep femoral vein oxygen content were determined at peak exercise in 53 patients with chronic heart failure with impaired systolic function (mean left ventricular ejection fraction 0.18; n = 41) or preserved systolic function (mean left ventricular ejection fraction 0.70; n = 12) and in 6 age-matched sedentary normal subjects. At peak exercise, deep femoral vein oxygen content in heart failure patients with impaired systolic function and preserved systolic function were similar, both significantly lower than that of normal subjects (2.5 +/- 0.1, 2.9 +/- 0.2, and 5.0 +/- 0.1 ml/100 ml, respectively; P < 0.05). Deep femoral venous oxygen content was lower in patients with the greater impairment of aerobic capacity, regardless of the underlying systolic function (r = 0.72, P < 0.01). Fractional oxygen extraction in the skeletal muscle at peak exercise is enhanced in patients with chronic heart failure when compared with normal subjects, in proportion to the degree of aerobic impairment.

Event-related brain potentials to Memory Workload and ‘Analytical-Specific Perception’ (Mangina-Test) in patients with early Alzheimer's Disease and in normal controls

Our previous research with intra-cerebral event-related potentials in conjunction with an original Memory Workload Paradigm has shown that significant load effects for the N4 latency were found only for both amygdalae and the left posterior hippocampus as well as for both anterior neo-cortical regions of the temporal gyri. These same structures are also affected in Alzheimer’s Disease. Therefore, based on our previous intra-cerebral findings, our present research was to use our novel Memory Workload Paradigm in conjunction with surface ERPs as neurophysiological markers to tap cerebral regions and functions involved in memory disorders pertaining to early Alzheimer’s Disease as opposed to normal memory processes in age-matched normal control subjects. Moreover, the Mangina-Test which measures varying degrees of ‘Analytical-Specific Visual Perception’ was individually administered to all patients and controls in separate sessions. Results indicate that for the early Alzheimer’s Disease group, a significant main effect for memory load was found for the P400 amplitude ( F 3,30=4.52, P<0.02) which was absent in the normal group. In particular, the P400 amplitude was significantly higher on posterior head regions for patients with early Alzheimer’s Disease as opposed to age-matched normal subjects ( F 7,140=3.54, P<0.03) which distinguished both groups ( F 1,20=6.13, P<0.03). For the P400 latency, a significant memory load effect was present only for the normal group ( F 3,30=11.26, P<0.01). The Mangina-Test performance clearly differentiated both groups ( F 1,19=105.85, P<0.001). The present data provide the first valuable evidence that ERPs to our novel Memory Workload Paradigm are sensitive neurophysiological diagnostic markers which delineate the early clinical brain irregularities underlying early Alzheimer’s Disease as opposed to the normal memory processes of age-matched normal subjects. In addition, their use could be valuable for the objective clinical follow-up of therapeutic interventions in early Alzheimer’s Disease.

Gait Variables of Patients After Lower Extremity Burn Injuries

Functional ambulation is an expected outcome of physical therapy after burn injuries on the lower extremities. The purpose of this study was to document temporal and spatial gait parameters of adult patients with the use of the GAITRite system (CIR Systems Inc, Clifton, NJ) after the patients were burned on their lower extremities and to compare these results with previous data reported for normal subjects. Twenty-five adults with lower extremity burns (19 men and 6 women; mean age, 35.6+/-8.3 years) were evaluated within 5 days of discharge from an acute care facility. The GAITRite system, which consists of an electronic walkway that contains 6 sensor pads encapsulated in a rolled-up carpet, was used to collect temporal and spatial variables. The patients walked at their preferred rate of ambulation and completed 2 passes; the 2 passes were then averaged by the software to determine the patients' gait parameters. A 2-tailed t test was used for comparison of the mean values for the patients and the previously published data. The results indicated that for both men and women, cycle time and base of support were significantly higher (P < or = .01) in the patients with burn injuries than in normal subjects. For men, all of the remaining parameters were significantly lower (P < or = .01) in the patients with burns except stride length, which was not significantly different (P > .05). For women, stance time as a percentage of the gait cycle and cadence, velocity, step length, and stride length, were all significantly lower (P < or = .01) in the patients with burn injuries, whereas double support as a percentage of the gait cycle was not significantly different (P > .05) between the 2 groups. These results indicate that immediately after an acute care hospitalization, patients with lower extremity burns have significantly different gait patterns than gender-and age-matched normal subjects. Future studies are necessary to determine whether these impairments in gait limit the functional abilities of a patient.

Immunostaining of heat shock proteins in the retina and optic nerve head of normal and glaucomatous eyes.

To examine immunostaining of 60-kd and 27-kd heat shock proteins (HSP 60 and HSP 27), which are known to increase cell survival in response to stress, in glaucomatous retina and optic nerve head. Six postmortem eyes from patients with primary open-angle glaucoma, 6 eyes from patients with normal-pressure glaucoma, and 6 eyes from age-matched normal subjects were studied by immunohistochemistry. The sections of the retina and optic nerve head were examined after immunostaining with antibodies to HSP 60 and HSP 27. The intensity of the immunostaining and the number of labeled cells for heat shock proteins (HSPs) were greater in retina sections from glaucomatous eyes than in sections from normal eyes from age-matched donors. Retinal immunostaining of HSP 60 was prominent in the retinal ganglion cells and photoreceptors, whereas immunostaining of HSP 27 was prominent in the nerve fiber layer and ganglion cells as well as in the retinal vessels. In addition, retinal immunostaining of these HSPs exhibited regional and cellular differences. Optic nerve heads of glaucomatous eyes exhibited increased immunostaining of HSP 27, but not HSP 60, which was mostly associated with astroglial cells in the lamina cribrosa. The increased immunostaining of HSP 60 and HSP 27 in the glaucomatous eyes may reflect a role of these proteins as a cellular defense mechanism in response to stress or injury in glaucoma. These findings suggest that immunoregulation is an important component of glaucomatous optic neuropathy.

Vestibular catch-up saccades in labyrinthine deficiency.

During rapid head rotations, saccades ipsiversive with compensatory vestibulo-ocular reflex (VOR) slow phases may augment the deficient VOR and assist gaze stabilization in space. The present experiments compared these vestibular catch-up saccades (VCUSs) with visually and memory-guided saccades. To characterize VCUSs and their relationship to deficiency of the initial VOR, we delivered random, whole-body transients of 1000 and 2800 degrees/s2 peak yaw acceleration around four different eccentric vertical axes in eight unilaterally and one bilaterally vestibulopathic subjects, as well as nine age-matched normal subjects. Eye and head movements were sampled at 1200 Hz using magnetic search coils. Subjects fixed targets at either 500 or 15 cm distance immediately before unpredictable onset of rotation in darkness. Under all testing conditions, normal subjects exhibited only compensatory vestibular slow phases and occasional anticompensatory quick phases. This behavior was also typical of unilaterally vestibulopathic subjects rotated contralesionally. When rotated ipsilesionally, however, vestibulopathic subjects had deficient slow-phase VOR gain with prolonged latency, and six of the nine exhibited saccadic movements in the compensatory direction (VCUSs). Higher head accelerations preferentially evoked VCUSs, but there were no preferred combinations of target distances and eccentric rotation axes. Peak velocities and durations of VCUSs increased with saccade amplitude. The latency distribution for VCUSs peaked around 70 ms, substantially shorter than reported for either visually guided express saccades or vestibular memory contingent saccades. The latency of each VCUS was highly correlated with the gaze error prior to that VCUS. The amplitude of VCUSs was calibrated to gaze position error, such that VCUSs reduced gaze error by an average of 37%. Thus when VOR slow-phase responses cannot compensate fully for head rotation, vestibular gaze position error can nevertheless calibrate the programming of VCUSs to augment the deficient VOR, much like catch-up saccades substitute for deficient visual pursuit.