Measurement of cytosolic Ca2+ concentration in Limulus ventral photoreceptors using fluorescent dyes.

Several Ca-sensitive fluorescent dyes (fura-2, mag-fura-2 and Calcium Green-5N) were used to measure intracellular calcium ion concentration, Cai, accompanying light-induced excitation of Limulus ventral nerve photoreceptors. A ratiometric procedure was developed for quantification of Calcium Green-5N fluorescence. A mixture of Calcium Green-5N and a Ca-insensitive dye, ANTS, was injected in the cell and the fluorescence intensities of both dyes were used to calculate the spatial average of Cai within the light-sensitive R lobe of the photoreceptor. In dark-adapted photoreceptors, the initial Cai was 0.40 +/- 0.22 microM (SD, n = 7) as measured with fura-2. Cai peaked in the light-sensitive R lobe at 700-900 ms after the onset of an intense measuring light step, when the spatial average of Cai within the R lobe reached 68 +/- 14 and 62 +/- 37 microM (SD, n = 5) as measured with mag-fura-2 and Calcium Green-5N, respectively. The rate of Cai rise was calculated to be approximately 350 microM/s under the measuring conditions. The resting level of Mg2+ was estimated to be 1.9 +/- 0.9 mM, calculated from mag-fura-2 measurements. To investigate the effect of adapting light on the initial Cai level in the R lobe, a 1-min step of 420 nm background light was applied before each measurement. The first significant (P < 0.05) change in the initial level of Cai occurred even at the lowest adapting light intensity, which delivered approximately 3 x 10(3) effective photons/s. The relative sensitivity of the light-adapted photoreceptors was linearly related to the relative Cai on a double log plot with slope between -4.3 and -5.3. We were unable to detect a Cai rise preceding the light-activated receptor potential. The Cai rise, measured with Calcium Green-5N, lagged 14 +/- 5 ms (SD, n = 32) behind the onset of the receptor potential at room temperature in normal ASW. In the absence of extracellular Ca2+ and at 10 degrees C, this lag increased to 44 +/- 12 ms (SD, n = 17).

Velocity profile in the main pulmonary artery in a canine model.

The velocity profile of the main pulmonary artery was determined in nine adult, open-chested, mechanically ventilated mongrel dogs using an intraluminal, needle-mounted, range-gated, pulsed Doppler technique. Mean phasic point velocities were determined at 2 mm intervals across the lumen of the vessel, 2 cm above the pulmonary valve, by recording the Doppler shift of an activated 20 MHz piezoelectric crystal, range-gated 3.5 mm in the direction of the pulmonary valve. Mean Reynolds numbers from the main pulmonary artery ranged from 275 to 1140. Radially normalised intraluminal distance versus mean phasic point velocity plots were constructed which demonstrated a curved profile in all 9 dogs. First order regression analysis demonstrated a poor fit (r: 0.05-0.68). Second order (r:0.61-0.97) and third order (r:0.72-0.99) regression analyses markedly improved the fit, confirming the non-linear nature of the velocity profile. Step-wise third order regression analysis to determine the importance of the entry sequence demonstrated that the most important term for determining the regression coefficient was the X2 term in six dogs. In addition, the velocity profile was noted to be shifted, with the highest velocities recorded between the centre of the vessel and the anterior wall in eight of nine dogs (location of highest velocity: +0.26 radius +/- 0.25 (mean +/- SD).

Two-dimensional in vivo pressure/diameter relationships in the canine main pulmonary artery.

Ultrasonic measurement of blood flow within the main pulmonary artery (MPA) requires a precise knowledge of the mean blood velocity within this vessel and the cross-sectional area (CSA). Small conformational changes in the elliptical shape of the MPA have substantial effects on the calculation of CSA and, subsequently, flow. We examined the extent of these changes by measuring the pulsatile and mean elliptical dimensions of the MPA in nine anaesthetised, open-chested, mechanically ventilated mongrel dogs using two pairs of 10 MHz ultrasonic, piezoelectric crystals. These custom-made devices were sutured to the PA adventitia along the long and short cross-sectional axes 2 cm distal to the pulmonary valve. Axial dimensions were collected during normal, elevated (via noradrenaline and fluid additions) and reduced (via exsanguination) PA pressures. We confirmed the linear pressure/diameter response in 15/18 axial data sets (r greater than 0.80). Further, the linear axial responses of the long and short diameters were parallel (7/9, p less than 0.05) and have different zero-pressure intercepts (7/9, p less than 0.0001). A mathematical consequence of this parallelism is predictable, although non-constant, eccentricity. Finally, error analysis of multi-axial measurement techniques were shown to improve CSA accuracy by as much as 50% when compared with uni-axial determinations.

The velocity profile in the canine ascending aorta and its effects on the accuracy of pulsed Doppler determinations of mean blood velocity.

The velocity profile in the ascending aorta, which has been variously reported as parabolic, skewed or flat, was measured using an intraluminal probe equipped with a miniature piezoelectric crystal activated by a 20 MHz pulsed Doppler with a 1 mm3 sample volume size. Phasic velocities, determined via spectral analyses, were obtained at 2 mm intervals across the aortic lumen of anaesthetised open-chest dogs by sequentially moving the crystal between posterior and anterior walls, maintaining the ultrasound beam parallel to the flow axis. Range-gating allowed data acquisition 3.5 mm proximal to the crystal, thus eliminating probe induced turbulence. Time and spatial distributions of velocities over the cross-section were computed. Expected errors in vessel mean velocity estimates based on point measurements were calculated. Analysis of phasic waveforms showed increased posterior velocities during systole but third order regression analysis of normalised point mean velocities across the lumen showed the best fit was a statistically flat straight line. Centreline referenced analyses indicated the expected difference between point mean velocity and vessel mean velocity was maximal (19.3 +/- 10.1%) 4 mm toward the posterior wall and minimal (4.7 +/- 9.1%) 5 mm toward the anterior wall. Anterior posterior wall referenced analyses indicated the most reliable position for estimating vessel mean velocity from point mean velocity along this axis was 5 mm from the anterior wall.

A minicomputer-based perinatal/neonatal telecommunications network.

A minicomputer-based telecommunications network has been developed to link all of the state's nine tertiary neonatal intensive care units in order to provide information on availability of neonatal and maternal beds. The information is updated automatically on computer terminals located in each neonatal intensive care unit every two hours by a complete system poll (350 polls per month). This information has been found to be accurate 95% of the time. Through a computer simulation, this network is shown to provide a significant reduction (P less than .0005) in the number of referral telephone calls, and thus the time, required to locate a bed within the state for obstetric or pediatric patients needing transfer. In addition, this network has provided a data base to aid in local, regional, and statewide planning for perinatal facilities. A 6-month summary of the data indicated that for 16% of the system polls, less than two neonatal intensive care units could accept outside referrals, demonstrating frequent severe statewide restrictions for care of high-risk patients. The total operating budget for the most recent fiscal year was less than +25,000, which is far less than that of manual 24-hour central telephone operator systems providing similar services. This telecommunications network is a cost-effective answer to the common problem of limited regional perinatal resources.

Constant postoperative monitoring of cardiac output after correction of congenital heart defects.

A new method has been developed that permits constant postoperative monitoring of mean and phasic cardiac output in patients after correction of congenital heart defects. A miniature ultrasound probe is attached to the adventitia of the ascending aorta at the conclusion of the operative procedure. This is connected to the monitoring equipment by means of polyurethane-covered wires that exit the chest wall through a small stab wound. The probe can easily be removed by gentle traction when the patient's condition is stable. The technique was developed, validated, and refined in extensive animal studies, and this report describes the first series of 20 consecutive human implants, performed between August 1984 and September 1985, in which the absolute cardiac output determination obtained with the ultrasound probe at the time of its application was correlated with cardiac output as measured with a standard electromagnetic flow probe. Fourteen male and six female patients (mean age 5.5 years) were studied. Operations performed included eight atrial septal defect repairs, four procedures for tetralogy of Fallot, three ventricular septal defect repairs, three stenotic valve corrections, and two Senning operations. One operative death occurred, but no complications were related to probe application or removal. The average cardiac output in the 20 patients as measured with the ultrasound probe was 2.2 +/- 1.1 L/min (range 0.67 to 5.27 L/min). This is nearly identical to the results noted with the electromagnetic flow probe, where the mean cardiac output was 2.3 +/- 1.2 L/min (range 0.7 to 6 L/min). Regression analysis revealed a high linear correlation (r = 0.9) between the two techniques. A monitor can display the cardiac output trend with 1 minute updates, which greatly enhance management of intravenous drug therapy and volume administration. In conclusion, this new extraluminal removable probe allows virtually continuous monitoring of the postoperative cardiac output after correction of congenital heart defects and should become a standard technique in the postoperative care of these patients.

Sonographic characteristics of the cavum velum interpositum.

BACKGROUND AND PURPOSE: Differential considerations for pineal region CSF collections include both true cysts and normal cystlike anatomic variations. Our purpose was to determine the sonographic characteristics of pineal region fluid spaces that reflect the presence of a normal persistent cavum velum interpositum (CVI). METHODS: Eighteen neonates and infants who had sonographic findings of "cysts" in the pineal region were examined prospectively with conventional sonography and color Doppler sonography to evaluate the shape of the fluid collection and its anatomic relationship with the color-coded internal cerebral veins. Subsequent MR images were obtained in eight of these infants to determine the exact nature of the cystlike collections. RESULTS: The cystlike spaces in the pineal region were of an inverted helmet shape in 14 subjects and roundish in four. All were situated inferior or slightly anteroinferior to the splenium of the corpus callosum and 2.5 to 4 mm away from the quadrigeminal plate. The internal cerebral veins were either inferior (n = 12) or inferolateral (n = 6) to the cystlike spaces at sonography. Subsequent MR studies confirmed eight of these cystlike spaces to be the posterior portion of the CVI. CONCLUSION: The CVI may appear as a cyst in the pineal region on neonatal sonograms. Usually, it has a characteristic inverted helmet shape and is situated beneath the fornices and above the internal cerebral veins.

Neuroimaging findings in late infantile GM1 gangliosidosis.

Late infantile GM1 gangliosidosis is an extremely rare metabolic disorder with clinical features of seizure and progressive motor and mental retardation without facial dysmorphism or visceral organomegaly. We report the CT and MR imaging findings in one infant, which included abnormalities of the cerebral cortex, white matter, and deep nuclei.

Software analysis of 20 MHz pulsed Doppler quadrature data.

A computer software procedure for processing quadrature data obtained from a 20 MHz pulsed Doppler system is described and the quality of results obtained is illustrated. The system is implemented on a standard laboratory minicomputer system. Software flexibility expands use of this high resolution device for measuring blood velocity to larger vessels than previously demonstrated. Techniques for dealing with high frequency aliasing, time delays, digital filtering and sampling intervals are included.

Synovial chondroma of the ankle in a young child after recent trauma: CT and MR features.

We report a case of synovial chondroma of the left ankle in an 11-year-old boy presenting with soft tissue swelling after recent trauma. The noncalcified or nonossified intraarticular chondroma arising from metaplastic synovium has characteristic imaging appearance on computed tomography (CT) and magnetic resonance imaging (MRI). A lobulated mass of fluid-like density and signal intensity along with internal septa are characteristic features on CT and MRI. The knowledge of CT and MRI features of noncalcified or nonossified synovial chondroma is important to distinguish from the simple or complicated effusion, hemarthrosis, or other synovial process.

Induction of perforated synapses in rat barrel cortex by whisker plucking.

To investigate synaptic alteration in the somatosensory cortex related to peripheral sensory blocking, the present study examined synapse number and structure within a single barrel following plucking of the C3 whisker of rat pups. The results indicate that whisker plucking produces no changes in synapse number and size, but does induce an early appearance of perforated synapses at P30 and P60, within the plucked whisker corresponding barrel. Thus, earlier occurrence of perforated synapses may indicate a representation of sensory experience.

Light-induced Mn2+ influx in Limulus ventral photoreceptors.

In contrast to insect species, light-activated influx of divalent ions into Limulus ventral photoreceptors has proven difficult to demonstrate. We used the quench of the fluorescent indicator dye, fura-2, to measure Mn2+ influx. Limulus ventral photoreceptors were injected with fura-2 and excited at 360 nm. When the photoreceptors were bathed in 1 mmol.l-1 Mn2+, an approximately 1% per 10 s decline in the fura-2 fluorescence during intervals between 50-ms flashes was taken as a measure of Mn2+ entry in darkness. Fluorescence decline during 10-s flashes was used to monitor Mn2+ entry during the photoresponse. During the 10-s flashes we observed a small rapid decline of the fura-2 fluorescence even in the absence of Mn2+. This reflected a contamination of the fluorescence signal arising from light-induced release of intracellular calcium stores. A subsequent slower decline in fluorescence during the 10-s flash, amounting to approximately 9% per 10 s, was only observed in the presence of extracellular Mn2+ and was attributed to Mn2+ influx. This light-activated influx was not through voltage-gated calcium channels since it persisted under voltage clamp, was not stimulated by depolarizing current injections, nor blocked by NiCl2. Depletion of internal calcium stores by cyclopiazonic acid treatment did not accelerate Mn2+ influx.

A microprocessor-based instrument to measure pulmonary functions in critically-ill newborn infants.

Despite advances in the medical care of critically-ill newborn infants, chronic complications due to intense ventilatory support are common. Selection of ventilator settings is empirical, since measurement of pulmonary functions in newborn infants is not commonly performed. A microprocessor-based instrument was constructed to measure pulmonary function in critically-ill newborn infants with respiratory failure. Data collected fail to demonstrate any beneficial effect upon pulmonary mechanics with increasing amounts of continuous distending airway pressure, and in fact demonstrate an adverse effect upon the lung ventilation. These results demonstrate the need to measure pulmonary function to develop procedures to select optimum ventilator settings. A microprocessor-based system is suitable for such an application, and could be incorporated into future infant respiratory support equipment.

A removable extraluminal Doppler probe for continuous monitoring of changes in cardiac output.

To address the problem of monitoring cardiac output in postoperative cardiac patients, a removable, extraluminal pulsed Doppler probe has been constructed which continuously reflects changes in cardiac output by monitoring blood velocity in the ascending aorta. Velocity is related to the frequency of the Doppler shift and the angle at which the ultrasound beam intersects the vessel. A 1 mm2 piezoelectric crystal mounted at a 45 degree angle on the tip of the probe is activated with a 20-MHz range-gated pulsed Doppler, and velocity is determined from Fourier analysis of quadrature data using computer software with a 50-KHz processing range. The device is designed for application to the ascending aorta at the conclusion of a cardiac surgical procedure; and, since mean diameter changes in the ascending aorta have been shown to be very small over a wide range of mean aortic pressures, cardiac output is linearly related to velocity. To test this technique, simultaneous recordings were made from the pulsed Doppler probe and an electromagnetic flow probe in five mongrel dogs over a range of cardiac outputs from 0.5 to 6 l/min for a total of 136 data points. Excellent correlation was found between the electromagnetic flow probe and pulsed Doppler probe data (average r = .98 +/- .006). Average slope between the two was 1.004 and average zero intercept was -0.025 l/min. The catheter is small, stable, has no baseline drift, and continuously and accurately reflects pulsatile changes at high and low flows.

Segmental hemorrhagic infarction of testis associated with epididymitis.

Testicular infarction is most commonly associated with acute testicular torsion. We present the sonographic findings in a case of segmental testicular infarction associated with epididymitis. The gray-scale abnormalities included a round, well-defined, hypoechoic intratesticular mass and heterogeneity and enlargement of the epididymis. Color Doppler sonography demonstrated only minimal blood flow in the intratesticular mass and increased flow in the epididymis. Recognition of acute testicular segmental infarction as a complication of epididymitis may prevent unnecessary orchiectomy.

A pulse method of measuring respiratory system compliance.

We describe a new method of measuring respiratory system compliance (Crs) that appears to detect whether respiratory muscles are relaxed. A pulse airflow, 0.3/s, is blown into the mouth through a pneumotachograph. Mouth pressure is recorded on the abscissa of an oscilloscope. Inflated volume, integrated from the flow signal, is recorded on the ordinate. After an initial step shift of pressure related to the flow resistance of the subject, pressure increases linearly at a rate inversely proportional to Crs. Crs is calculated from the slope of the volume-pressure line. With relaxed subjects, repeated pulses yield straight lines with similar slopes (mean coef of variation = 4.8%). When subjects are not relaxed, the pulse produces irregular lines. In 15 normal subjects who could relax. Crs averaged 0.86 +/- 0.016 (SD) 1/cmH2O. When normalized for body size by dividing by the vital capacity, the mean value was 0.021 +/- 0.0024 cmH2O-1, which agrees with published values. We conclude that the pulse method accurately measures Crs and has the advantage of detecting respiratory muscle relaxation.

Primary chiasmal sarcoid granuloma: MRI.

We report MRI findings of a pathologically proven primary sarcoid granuloma of chiasmal origin that mimicked an optic pathway glioma

Compliance of chest wall in obese subjects.

Whereas studies in awake subjects have demonstrated that chest wall compliance (Ccw) is low in obese subjects, the one study performed on paralyzed obese subject found Ccw to be normal. The purpose of this study was to measure Ccw in awake obese subjects with the pulse-flow technique, a method which appears to detect respiratory muscle relaxation. Seven normal males, 14 obese males, and 8 obese females [body mass index (BMI) varied from 20 to 83 kg/m2] were studied in the seated position. Ccw was measured by blowing air at a constant flow into the mouth and lungs for approximately 2 s and calculated by dividing airflow in liters per second by the change in esophageal minus body surface pressure in centimeters of water per second. In normal and obese subjects we found no correlation between BMI and Ccw. We conclude that obesity does not decrease Ccw.

Imaging of huge lingual thyroid gland with goitre.

We present the CT and MRI findings in a 75-year-old woman with a huge pathologically proven lingual thyroid which underwent goitrous degeneration. CT and MRI showed a midline, tongue-based, exophytic mass with areas of necrosis and heterogeneous contrast enhancement, as seen in large goitres in the normal thyroid gland.