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The goal of this study was to show whether a correlation exists between the intensity of specific respiratory muscle training and the improvement of strength and endurance in inspiratory musculature in patients with neuromuscular disorders (NMD). Sixteen patients with NMD (13 with Duchenne muscular dystrophy and 3 with spinal muscular atrophy) performed inspiratory muscle training (IMT) at home with a special training apparatus for 9 months. Maximal inspiratory mouth pressure (PIMAX) and 12s‐maximum voluntary ventilation (12s‐MVV) test served as parameters for inspiratory muscle strength and endurance, respectively. In patients whose inspiratory vital capacity (VCin) declined by less than 10% during the year before training began (n= 10), a significant positive correlation was found between the number of successfully completed strength and endurance exercises and the improvement of PIMAX(P< 0.05) and 12s‐MVV (P< 0.05). In patients whose VCin‐decline exceeded 10% (n= 6), indicating more progressive respiratory system involvement of the disease, no significant correlation between the improvement of PIMAXand 12s‐MVV and the intensity of training was found. In patients with NMD, the effects of IMT‐runs are dose‐dependent, provided that the respiratory system involvement of the disease is only slowly progressive. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 1257–1260, 2000.

The goal of this study was to show whether a correlation exists between the intensity of specific respiratory muscle training and the improvement of strength and endurance in inspiratory musculature in patients with neuromuscular disorders (NMD). Sixteen patients with NMD (13 with Duchenne muscular dystrophy and 3 with spinal muscular atrophy) performed inspiratory muscle training (IMT) at home with a special training apparatus for 9 months. Maximal inspiratory mouth pressure (PIMAX) and 12s-maximum voluntary ventilation (12s-MVV) test served as parameters for inspiratory muscle strength and endurance, respectively. In patients whose inspiratory vital capacity (VCin) declined by less than 10% during the year before training began (n = 10), a significant positive correlation was found between the number of successfully completed strength and endurance exercises and the improvement of PIMAX (P &lt; 0.05) and 12s-MVV (P &lt; 0.05). In patients whose VCin-decline exceeded 10% (n = 6), indicating more progressive respiratory system involvement of the disease, no significant correlation between the improvement of PIMAX and 12s-MVV and the intensity of training was found. In patients with NMD, the effects of IMT-runs are dose-dependent, provided that the respiratory system involvement of the disease is only slowly progressive. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 1257–1260, 2000.

The optical performance of the eyes of nine vertebrate species was evaluated using optical system design techniques and schematic eye models. Essential features of eyes, including the modulation transfer function (MTF) and the MTF cutoff frequency are related to the numerical aperture of the eyes. Superior resolution for in vivoimaging of photoreceptors may be achieved by dilating the iris pupil of an eye, minimizing coherence, and using short wavelength illumination. The difference of lateral and axial resolution between a small and a large eye for imaging photoreceptors in vivo. © 2000 Society of Photo-Optical Instrumentation Engineers.

A new gas filter correlation spectrometer (gaspec), for the remote detection of trace vapors in the atmosphere by means of natural emission in the ir, is described. Unique optical features of the gaspec include two detectors using a single focal plane chopper plus an optical reference for electronic gain balancing. Continuous sensor balance and calibration are achieved along with the source radiometric and target gas information. Several gaspec instruments have been built and tested including devices to sense CH_4, C_2H_6, HCl, and CO. Some preliminary data taken with these sensors are presented.

Abstract: A microprocessor-controlled light-emitting diode (l.e.d.) display is used to measure dark adaptation. The apparent intensity of the l.e.d. display is controlled by varying the pulse width while holding the pulse repetition rate constant. During the period of dark adaptation, the absolute threshold is measured by the method of limits. Separate series of threshold values are obtained for red and green l.e.d. stimuli. The design uses inexpensive programmable and conventional integrated circuits. Stimulus parameters, test administration, and data acquisition are under software control. The dark adaptation functions derived with this device are comparable to those obtained with other instruments.

The aim of our study was to examine the effect of posture on inspiratory muscle activity response to hypercapnia. Recent research has revealed that in normal subjects the activation of the rib cage muscles and of the diaphragm is actually greater in the upright than in the supine position during resting tidal breathing. In this study we examined whether the upright position necessarily entails a greater activation of the inspiratory muscles also under conditions of ventilatory stress. For this purpose we compared the responses to CO2-rebreathing in the supine and sitting positions in five volunteers, by simultaneously recording the electromyogram of the diaphragm (EMGdi) and the intercostal muscles (EMGint). The electromyogram was recorded by means of surface electrodes to measure the EMG amplitude. While the slopes of ventilatory (VE) response to increasing arterial CO2 tension (PaCO2) were similar in the two positions, both the EMGdi-VE and EMGint-VE relationship showed steeper slopes in the supine than in the sitting position. In each CO2 run the increases in EMGdi were linearly related to those in EMGint. This relationship was not affected by the body position. These results suggested that, in spite of similar ventilatory responses to CO2-rebreathing in the lying and sitting positions, the supine position, in humans, required a higher activation of the inspiratory muscles.

Spectrooptical and water quality data collected from a 1979 coordinated in situ and airborne study of western Lake Ontario are used to devise a five-component model from which subsurface chlorophyll a and suspended solids concentrations may be determined from submersible optical sensors capable of measuring spectral irradiance reflectance just beneath the free-surface layer. A water–air interface model, which incorporates the effects of surface reflection, is also presented in an attempt to extend such water quality estimations to low altitude remote sensors. Special emphasis is given to the spectral wavelength bands of the Coastal Zone Color Scanner aboard Nimbus-7.

A five-component optical model of Lake Ontario is discussed in terms of unique organics (as represented by chlorophyll a), unique inorganics (as represented by total suspended minerals), unique nonliving organics, and unique dissolved organics. Direct measurements of the irradiance attenuation coefficient K(0), the diffuse reflectance R(0), and the total atttenuation coefficient c are used in conjunction with simulated solutions of the radiative transfer equations to determine the inherent optical properties of the water masses. Multiple regressions between these inherent optical properties and directly measured water quality data are then performed to determine the absorption, scattering, and backscattering cross sections of the organic and inorganic components.

Maximal visual acuity and normal color vision are closely associated with foveal receptor function. When the fovea is destroyed or altered by intense laser irradiation, severe and sometimes permanent losses in visual acuity ensue. In this paper we have shown that the threshold for long-term functional alterations in the fovea is determined not only by the wavelength and corneal exposure power of a laser flash but also by the types of performance criteria used to assess visual functioning. Chromatic acuity provides a much lower threshold for permanent alterations (Krypton — 6 mW; Argon — 3 mW) as opposed to achromatic targets (HeNe — 11 mW). Further, the use of chromatic acuity to assess post-exposure functioning can more accurately delineate the specific cone process most affected by the exposing source. The data from these studies also suggest that some relatively long-term (24 h) cumulative process within the retina is occurring which obviously will affect any threshold value determined.

The aim of this study was to evaluate the difference between Type 1 (insulin-dependent) diabetic patients and healthy control subjects regarding inspiratory muscle load during exercise hyperpnea. For this purpose an incremental progressive exercise test on a cycle ergometer was performed by 36 Type 1 diabetic patients and 40 healthy subjects. In order to determine the mechanical load on the inspiratory muscles breath by breath, we selected the following two parameters, which represent the pressure generated by the inspiratory muscles as well as the duration and velocity of their contraction: (1) the oesophageal tension time index, which is the product of the duty cycle (ratio of inspiratory time to total breath cycle duration) and the mean oesophageal pressure expressed as a percentage of the maximal oesophageal pressure and (2) the mean oesophageal pressure change per time unit during the inspiratory phase of each breathing manoeuver, which is expressed as a fraction of the subject's maximal oesophageal pressure. Comparison of the two groups revealed that at similar levels of ventilation the mechanical load on the inspiratory muscles was significantly higher in the Type 1 diabetic patients than in the control subjects. When the loading was stopped the maximal ventilation was lower in the patients. Nevertheless, they reported a degree of respiratory effort sensation comparable to the control group, which seems to have been caused by an increase of the mechanical load on the ventilatory muscles.

We investigated 8 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) for diaphragmatic strength and the neuromechanical efficiency of the diaphragm while the abdomen was filled with dialysate and while it was empty. Maximum transdiaphragmatic pressure (Pdimax) served as parameter for diaphragmatic strength; diaphragmatic efficiency was assessed by simultaneously monitoring transdiaphragmatic pressure (Pdi) and diaphragmatic electromyogram (EMGdi) during room-air breathing and hyperoxic CO2-rebreathing. After instilling dialysate, Pdimax increased from 76.7 ± 12.1 cmH2O to 92.2 ± 16.3 cmH2O (P < 0.05). While the slopes of the regression lines relating minute ventilation (VE) to arterial CO2 tension, and the change in VE for a given change in Pdi during hypercapnic rebreathing were similar in both states, the slope of EMGdi vs Pdi was significantly steeper when the abdomen was filled (P < 0.05). The increase in Pdimax observed in the filled state may suggest an adaptive rightward shift in the diaphragm's force-length relationship in CAPD patients, although this mechanism is insufficient to prevent a reduction of neuromechanical efficiency of the diaphragm.

The energy demand during physical exercise causes an increased oxygen uptake and supply to active tissues, which may increase the rate of free oxygen radical production and thereby affect the capacity of endogenous cellular defense systems. This could result in DNA base modifications, among which 8-hydroxydeoxyguanosine (8OHdG) is one of the most important and has widely been used as a biomarker of in vivo oxidative lesions. Therefore, we examined the effect of regular running exercise on the urinary levels of 8OHdG in 32 long-distance runners and in a group of untrained healthy subjects. The range of 8OHdG in urine was 0.12–6.45 µmol/mol creatinine in both groups, and no significant difference in the mean excretion levels between runners and control probands was observed. This gives no reason to believe that physical exercise in trained individuals may induce a disturbance of the oxidant-to-antioxidant balance.