Vitamin A deficiency and nocturnal vision in teenagers with cystic fibrosis

The aim of this study was to document plasma retinol status and nocturnal vision in ten eutrophic adolescents with cystic fibrosis (CF) receiving daily retinol supplementation. Plasma retinol, alpha and beta carotenes and retinol binding protein were measured in ten clinically stable CF patients (mean age: 14.3 years; Shwachman score: 80-100). Nocturnal vision evaluation was performed with a Beyne optometer. Plasma retinol (mean 0.42 +/- 0.16 mg/l), alpha carotene and beta carotene levels were below the lower limit of normal in all but one patient. Five out of ten patients with normal standard opthalmological examination presented a poor (n = 3 patients) or a pathological (n = 2) dark adaptation test. These two patients showed a dramatic increase in nocturnal vision after 1 year of adapted retinol supplementation. CONCLUSION: Low vitamin A levels occur frequently in clinically stable, eutrophic and retinol supplemented CF adolescents. Since vitamin A deficiency is associated with poor nocturnal vision and since this pattern can be reversed by adapted retinol supplementation, we recommend monitoring plasma vitamin A levels in CF patients and evaluation of dark adaptation in retinol deficient patients.     

Endosonographic features of esophageal granular cell tumors

BACKGROUND AND STUDY AIMS: Granular cell tumors of the esophagus are rare tumors. A definite diagnosis is achieved by endoscopic biopsies in only 50% of cases. Endoscopic ultrasonography (EUS) is the best procedure in the evaluation of upper gastrointestinal tract submucosal tumors. The aim of this study was to describe the endosonographic findings of esophageal granular cell tumors. METHODS: From January 1989 to March 1994, 15 patients with 21 granular cell tumors which had negative biopsies were examined by EUS (Olympus GF UM3 or GF UM20,7,5 and 12 MHz). In five cases, the tumor was also studied with a 20 MHz Olympus miniprobe. The final histological diagnoses were obtained by subsequent endoscopic snare resection in 20 cases and surgically in one case. RESULTS: The endosonographic features (with the GF UM3 or GF UM20) of esophageal granular cell tumors were: a) a tumor size of less than 2 cm in 95% of cases; b) an hypoechoic solid pattern in 100% of cases; c) a tumor arising in the inner layers in 95% (second echo-poor layer n=15; third echo-rich layer n=5). In one case, the endosonographic finding was transmural malignant infiltration of the esophageal wall (histologically confirmed). CONCLUSION: When a granular cell tumor of the esophagus is suspected, EUS can show the inner layer location of the tumor and thus contribute to planning the endoscopic resection or follow up. When the tumor also invades the outer layers, EUS can contribute to planning the surgical resection.     

Giuseppe Gradenigo and his contributions to audiology

Giuseppe Gradenigo (1859-1926) was an important figure in the development of Otology. Within this paper the authors consider his background and his particular contributions to the development of various aspects of audiology.     

Agenesis of the corpus callosum in a mother and son

Most reported familial cases of agenesis of the corpus callosum have followed either an autosomal recessive or an X-linked recessive pattern of inheritance. To the best of our knowledge, there is only one previous report of a family showing clear-cut autosomal dominant inheritance. We present the second such family, among whom a mother and her son had moderately severe coordination problems and low-normal intelligence. We suggest that agenesis of the corpus callosum, when transmitted as an autosomal dominant trait, is clinically characterized by a relatively milder phenotype than that occurring when inheritance is either autosomal or X-linked recessive and may be more common than has been thought.     

Microfabricated Lamb wave device based on PZT sol-gel thin film formechanical transport of solid particles and liquids

The fabrication using silicon micromachining and characterization of an acoustic Lamb wave actuator is presented. The intended use of the device is for mass transport and sensor applications. The device consists of dual interdigitated transducers patterned on a thin-film composite membrane of silicon nitride, platinum, and a sol-gel-derived piezoelectric ceramic (PZT) thin film. The acoustic properties of the device are presented along with preliminary applications to mechanical transport and liquid delivery systems. Improved acoustic signals and improved mass transport are achieved with PZT over present Lamb wave devices utilizing ZnO or AlN as the piezoelectric transducer     

A robust CMOS compander

A robust CMOS compander circuit meeting all of the requirements for analog cellular telephony and using an improved sigma-delta compander topology is presented. Rather than digitizing and reconstructing the input signal using a sigma-delta modulator as has been done previously, only the amplitude path is digitized while the voice path remains analog. The amplitude information is obtained digitally, and is reduced to a single bit using a first-order sigma-delta modulator. Performing this function digitally eliminates problems due to analog offsets and in implementing the long time constant required. The output signal is formed by gating the analog input signal under control of the amplitude signal. The expander and compressor circuits each consist of a single op amp and 2000 gates of digital logic, and have been implemented on 0.8-μm CMOS processes. The ADC for the amplitude path uses a compact switched-capacitor second-order sigma-delta modulator implemented using a single amplifier. No external components are required. Tracking error for the compressor was measured to be less than 0.3 dB over a 60-dB input range when operating on a 3.0-V supply. The test time, when compared to conventional compander implementations, is considerably reduced     

A transimpedance CMOS multichannel amplifier with a 50 Ω-wideoutput range buffer for high counting rate applications

A fast transimpedance multichannel amplifier has been designed, fabricated in CMOS 1.2-μm technology and tested. Each channel consists of a current sensitive preamplifier followed by a voltage amplification stage and an on-chip buffer able to drive 50 Ω loads with an output range of ±800 mV. Measured peaking time at the output is 40 ns and the circuit recovers to baseline in 90 ns. This results in a counting capability of more than 10⁷ hits/s, Signals of both polarities can be handled. The first two stages consume a total of 2 mW per channel and the 50 Ω buffer consumes another 17 mW. The equivalent noise charge (ENC) is 1100 e^- rms with a slope of 40e^-/pF. The IC is intended for use in gas and solid-state detectors with high particle rate and extensive charge release as in high energy calorimetry     

A Metallographic Study of the High-Temperature Decomposition of Austenite in Alloy Steels Containing Mo and Cr

Optical and electron microscopy have been used to study the complex microstructures developed during the isothermal decomposition of austenite above 550°C in Fe-4Mo-0.2C and Fe-10Cr-0.4C alloy steels. As the transformation temperature is decreased, the decomposition products change from the disordered growth of nodular alloy pearlites to blocky ferrite structures containing fine dispersions of alloy carbide, and finally to acicular ferrite structures also containing alloy carbide. The branched M₆C and M₂₃C₆ of the high-temperature pearlite is replaced by Mo₂C and M₇C₃ with a fibrous or lath morphology in the lower temperature structures. The decomposition microstructures are explained in terms of a model which takes account of the growth of particular alloy carbides at the interfaces of ferrite allotriomorphs, where the growth mechanism, and hence the morphology, is sensitive to transformation temperature.     

Supramedullary modulation of sympathetic vasomotor function

1. Supramedullary structures including the ventral medial prefrontal cortex (MPFC) and the midbrain cuneiform nucleus (CnF) project directly and indirectly to premotor sympatho-excitatory neurons of the rostral ventrolateral medulla (RVLM) that are critically involved in the generation of sympathetic vasomotor tone. 2. Electrophysiological studies have demonstrated that activation of depressor sites within the MPFC is associated with splanchnic sympathetic vasomotor inhibition and inhibition of the activity of RVLM sympathoexcitatory neurons. 3. Antidromic mapping and anatomical studies support the notion that a relay in the nucleus tractus solitarius is involved in the cardiovascular response to MPFC stimulation. 4. The midbrain CnF, which lies adjacent to the midbrain periaqueductal grey, is a sympathoexcitatory region of the midbrain reticular formation. Sympathoexcitatory responses evoked from the CnF are associated with short-latency excitation of RVLM neurons. 5. Cuneiform nucleus stimulation induces the expression of mRNA for the immediate early genes c-fos and NGFI-A in mid-brain, pontine and hypothalamic structures. 6. The MPFC and CnF are supramedullary structures with opposing modulatory influences on sympathetic vasomotor drive, whose roles in cardiovascular control mechanisms warrant further investigation.