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Biomedical subjects

R Pratesi

Publications and source records attributed to R Pratesi.

At least 37 records · Page 2Linked to original sources
PubMed1993

Anthropometric and craniofacial patterns in mentally retarded males with emphasis on the fragile X syndrome.

Anthropometric and craniofacial profile patterns indicating the percent difference from the overall mean were developed on 34 physical parameters with 31 white, mentally retarded males (23 adults and 8 children) with the fra(X) syndrome matched for age with 31 white, mentally retarded males without a known cause of their retardation. The fra(X) syndrome males consistently showed larger dimensions for all anthropometric variables, with significant differences for height, sitting height, arm span, hand length, middle finger length, hand breadth, foot length, foot breadth, and testicular volume. A craniofacial pattern did emerge between the two groups of mentally retarded males, but with overlap of several variables. Significant differences were noted for head circumference, head breadth, lower face height, bizygomatic diameter, inner canthal distance, ear length and ear width, with the fra(X) syndrome males having larger head dimensions (head circumference, head breadth, head length, face height and lower face height), but smaller measurements for minimal frontal diameter, bizygomatic diameter, bigonial diameter, and inner canthal distance. Several significant correlations were found with the variables for both mentally retarded males with and without the fra(X) syndrome. In a combined anthropometric and craniofacial profile of 19 variables comparing 26 white fra(X) syndrome males (13 with high expression (> 30%) and 13 with low expression (< 30%), but matched for age), a relatively flat profile was observed with no significant differences for any of the variables. Generally, fra(X) syndrome males with increased fragile X chromosome expression have larger amplifications of the CGG trinucleotide repeat of the FMR-1 gene. No physical differences were detectable in our study between fra(X) males with high expression and apparently larger amplifications of the CGG trinucleotide repeats compared with those patients with low expression. Our research illustrates the use of anthropometry in identifying differences between mentally retarded males with or without the fra(X) syndrome and offers a comprehensive approach for screening males for the fra(X) syndrome and selecting those individuals for cytogenetic and/or molecular genetic testing.

Adolescent↗
PubMed1992

Wavelength-dependent quantum yield for Z----E isomerization of bilirubin complexed with human serum albumin.

The quantum yield, phi ZE, for configurational photoisomerization (4Z,15Z----4Z,15E) of bilirubin bound non-covalently to human serum albumin was determined (at 23 +/- 2 degrees C) by laser excitation and chromatographic analysis of products. Values obtained for photoexcitation at 465 nm were about one-half those previously reported. The quantum yield was dependent on excitation wavelength, decreasing from a value of 0.109 +/- 0.010 for excitation at 457.9 nm to a value of 0.054 +/- 0.005 for excitation at 514.5 nm. The wavelength dependence is consistent with rapid transfer of excitation energy between the two non-identical pyrromethenone chromophores of bilirubin in the singlet excited state. Since the quantum yields for photoisomerization and luminescence of bilirubin bound to serum albumin at room temperature are both low, internal conversion processes, rather than Z----E configurational isomerizations, are probably the major pathways for deactivation of photo-excited bilirubin.

Bilirubin↗
PubMed1992

[The use of Opticath in the correct measurement of the pulmonary capillary wedge pressure].

The Authors assess the utility of the on-line monitoring of SvO2 during 156 measurements of pulmonary capillary wedge pressure (PCWP) done on 52 Intensive Care Unit patients. The measurement was always right when the SvO2 increased more than 90%. The Authors found a good correlation between the SvO2 monitored during the measurement of the PCWP and the saturation of pulmonary capillary blood measured by cooximeter. These data suggest that the complex procedure to confirm the reliability of the measurement recommended by Gardner can be simplified by the observation of the trend of SvO2 on the monitor oximetrix. This allows to obtain saving time for the staff, saving blood for the patients, reduction of risk for the transmission of infective diseases due to the handling of blood and guarantees a further routinary control of reliability on the measure of PCWP.

Catheterization, Swan-Ganz↗
PubMed1991

[Cardiac tamponade: an unusual cause. Clinical case].

The Authors describe an unusual case of acute cardiac tamponade caused by fistulization in the pericardial cavity of an amebic abscess of the left lobe of the liver. The availability of echocardiography facilitated prompt diagnosis and treatment.

Adult↗
PubMed1990

[Russel's syndrome: diencephalic tumor in a child].

The case of a male child with Russel's syndrome due to a pilocytic astrocytoma located in the diencephalic region is presented. The diagnosis was made in the 16th month of age, but symptoms began in the 4th months of life, when he started losing weight. By the time he was admitted weight was 6150g and he was 74cm tall, with an emaciated aspect, no panniculus adiposus, irritated, and with symptoms of intracranial hypertension. There was convergent strabismus, vertical nystagmus of the left eye and bilateral papilledema. Tendinous reflexes were exacerbated and he had spastic tetraparesis. The endocrine evaluation showed a basal raise of GH (23ng/ml), TSH (6.2mUI/1) and prolactin (26ng/ml). The first two hormones did not respond to the acute test with TRH, while prolactin had a poor response. He was submitted to radiotherapy with linear acceleration (total dose of 4000 rads) and surgery, during which the tumor could not be completely removed due to its large size. After 9 months, the child is doing well, with a considerable weight gain (2500g).

Astrocytoma↗
PubMed1989

Quantum yields for laser photocyclization of bilirubin in the presence of human serum albumin. Dependence of quantum yield on excitation wavelength.

The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (phi LR) was measured at five monochromatic excitation wavelengths in the range 450-530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XIII alpha impurities. The values obtained (7.2-18 x 10(-4] were lower than those previously reported and showed the following wavelength dependence: 457.9 less than 488.0 less than 501.7 less than 514.5 approximately equal to 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15E and 4E,15Z isomers also was studied. This reaction became less regioselective for the 4Z,15E isomer with increasing wavelength. The observed wavelength dependence of phi LR and of the [4E,15Z]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formation in vivo at different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength-dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorption maximum.

Bilirubin↗
PubMed1989

Phototherapy for neonatal hyperbilirubinemia.

New light has recently been shed on the way phototherapy reduces bilirubin concentration in icteric infants. The introduction of a high-performance liquid chromatography technique led to the discovery of new photoisomers of bilirubin, the configurational and structural isomers with high and low quantum yields, respectively, and to a renewed interest in the photochemical properties of bilirubin in vitro and in vivo. Circular dichroism and absorption spectroscopies have then shown that bilirubin behaves like a bichromophoric system, with the 2 halves of the molecule strongly interacting in the excited state. This coupling mechanism makes the quantum yields of bilirubin photochemistry wavelength-dependent, with marked effects in the long wavelength edge of the bilirubin absorption spectrum. The photochemistry of bilirubin is substantially similar in icteric rats and babies, and is consistent with what is observed in vitro. However, the metabolism of bilirubin photoproducts in rats sometimes differs quite significantly from that in babies. In particular, only the low quantum yield structural isomer, lumirubin, is efficiently excreted by babies. Although the relative role of the bilirubin photoprocesses in the therapy of hyperbilirubinemia is not yet known with certainty, the structural photoisomerization is generally assumed to represent the main route of bilirubin elimination. As a consequence, the determination of the spectral band that optimizes the process of formation of lumirubin in neonate may represent an important step in the improvement of the clinical protocol of phototherapy. Therefore, in addition to reviewing the most recent data on bilirubin photochemistry and the metabolism of bilirubin products, this article presents a computation of the optimal light for lumirubin formation. The combined effects of long-wavelength photochemistry of bilirubin and skin attenuation show that the optimal spectral range should be between 480 and 510 nm.

Chromatography, High Pressure Liquid↗
PubMed1989

Histopathology of diode and argon laser lesions in rabbit retina. A comparative study.

Argon lasers are the most frequently used laser source for retinal photocoagulation. These are expensive, bulky and low-efficiency devices. In contrast, diode semiconductor lasers have a number of characteristics that make them attractive for medical application: compact size, high electrical-to-optical efficiency, and long operating lifetime. Comparable irradiance lesions (about 120 Wcm2), ophthalmoscopically similar to those obtained therapeutically in humans, were obtained by a diode and an argon laser. Twenty-four hours after the treatment, a study of these lesions was made by light and electron microscopy. Argon irradiations resulted in damage to both the inner and the outer retinal layers, while the diode laser radiation produced damage to the outer retina and choroid. A sufficient diode laser light passed into the choroid to induce small vessel occlusions and/or edema. The histological characteristics of the lesions produced by the two lasers suggest the use of the diode lasers, as well as argon lasers, in the treatment of retinal and subretinal pathologies.

Animals↗
PubMed1986

Phototherapy for neonatal jaundice: clinical equivalence of fluorescent green and "special" blue lamps.

The relative efficacy of fluorescent green (Sylvania F20T12/G) and "special" blue (Westinghouse F20T12/BB) lamps in the phototherapy of jaundiced neonates was investigated. Two groups of low birth weight infants with a mean gestational age of 35 weeks and mean birth weight of 1930 gm, who developed hyperbilirubinemia within the first 5 days of life, were given green or blue lamp phototherapy under the same irradiation conditions. No statistically significant difference in plasma bilirubin concentrations was found between the two groups after 24 or 48 hours of treatment. Because recent measurements indicate that green lamps are much less efficient than special blue lamps for the production of Z, E isomers of bilirubin in vitro and in vivo, the clinical equivalence of these two types of lamps seems to support the hypothesis that production of structural photoisomers of bilirubin is the main mechanism of phototherapy in humans. Therefore, fluorescent green lamps provide an alternative to special blue lamps for treatment of neonatal hyperbilirubinemia.

Bilirubin↗
PubMed1986

[Alexia without agraphia: a clinico-tomographic study].

The authors report the clinical findings and CT-scanning results in two cases of alexia without agraphia and review the literature on this subject. Both patients had extensive infarction in the territory supplied by the left posterior cerebral artery and developed severe alexia without agraphia, right hemianopia without color-anomia and one of them presented with transient verbal memory difficulties. In both cases the evolution was very good, with total regression of the alexia after 17 months in the first patient and almost complete recovery after there months in the second one. The authors comment on the causes and possible mechanisms of the alexias, especially of the alexia without agraphia, and suggest that every patient with right hemianopic disturbances due to occlusion of the left posterior cerebral artery be thoroughly studied from a neurological point of view, so that this syndrome can be detected since, notwithstanding its recognized rarity, it seems highly probable that many cases have been overlooked as a result of incomplete examination of the patients.

Adult↗
PubMed1985

Laser investigation of bilirubin-photobilirubin photoconversion.

The reversibility of the configurational photoisomerization process of bilirubin (BR) with laser lines in the blue-green spectral region is investigated. Photoisomerization efficiency of BR is found to depend strongly on wavelength, and to decrease when the excitation wavelength is increased from blue to green. Reversion of BR photoisomers (identical to photobilirubin, PBR) back to native BR is demonstrated for several laser lines by irradiating PBR/BR mixtures with wavelengths greater than the excitation wavelengths. Green lines turn out to be very efficient for PBR----BR reversion. The PBR concentrations at photoequilibrium, obtained from the spectrophotometric data, are in close agreement with the corresponding values measured with the high performance liquid chromatography technique in the case of 10 nm bandwidth filtered light reported in the literature. The 457 nm blue laser line produces 32% PBR concentration at photoequilibrium; only 14, 7, and 3% PBR concentrations are produced by the blue-green lines at 488, 501, 514 nm, respectively. The effect on the photostationary PBR/BR mixture of successive irradiations with different wavelengths, and the influence of the wavelength sequence are reported. In the case of blue lines our results support the assumption of the first-order kinetics for the BR in equilibrium PBR photoreaction. Departures are observed with green-lines (501, 514 nm). The present results, together with the i) good clinical efficiency reported for fluorescent green lamps; and ii) slow elimination of configurational photoisomers in infants, tend to confirm the lumirubin-pathway as the main mechanism for phototherapy, and call for clinical investigation of narrow-spectrum lamps with peak emission wavelength in the (biologically safer) 480 divided by 530 nm range.

Bilirubin↗
PubMed1984

GAPO syndrome: report of three affected brothers.

We present a sibship of three brothers affected with the GAPO syndrome. This is a rare and very characteristic autosomal-recessive trait whose main manifestations are growth retardation, alopecia, pseudo anodontia, and optic atrophy. So far nine affected individuals are known (4 males and 5 females). Two of them, the patient of Andersen and Pindborg cited in Tipton and Gorlin [1983] and one of the cases of Wajntal et al [1982], died at 39 and 37 years respectively.

Alopecia↗