Comparison of conventional single echo and multi-echo sequences with a fast spin-echo sequence for quantitative T2 mapping: application to the prostate

The accuracy of water T2 maps generated from a fast spin-echo (FSE) sequence was compared with data obtained by conventional single and multi-echo spin-echo pulse sequences using a commercial gel phantom. Spatially localized stimulated echo acquisition mode (STEAM) proton spectroscopy was also used to confirm the reported water T2 values of the gels contained in the phantom. The FSE sequence was shown to be superior in accuracy to both the single and multi-echo spin echo sequences and comparable to STEAM, producing results that were within 10% of known values. The effectiveness of the FSE sequence was further demonstrated by generating T2 maps of the normal and diseased prostate in clinically acceptable imaging times, resulting in comparable T2 values to those obtained using STEAM. Accurate quantitative T2 maps can be produced with the FSE sequence.     

Topical laryngo-tracheal anesthesia and intraocular pressure in anesthesia for ophthalmic surgery

OBJECTIVE: The reflex response to orotracheal intubation provokes an increase of arterial pressure accompanied by an increase of chorioides volume and a consequent ocular hypertone. There are several methods to reduce the reflex response due to intubation. One of the most effective is topical anaesthesia of larynx and trachea. Experiments were directed to evaluate the efficacy of topical anaesthesia to reduce the intraocular hypertone due to orotracheal intubation. DESIGN: A prospective randomized mask study was conduct on patients undergoing ophthalmologic (anterior segment) surgery at the Eye Clinic of Florence University. METHODS: Intraocular pressure was measured by a Goldman tonometer at four times: T0 = basal, T1 = 2' minutes after induction of general anaesthesia, T2 = 2' minutes after laryngoscopy, T3 = 2' minutes after orotracheal intubation. At the same moments, systolic blood pressure, heart rate, rate pressure pro duct were measured. Patients were randomly divided in two groups: Group L (n = 10) in which was evaluated the efficacy of laryngotracheal topical spray of lidocaine 4% (2 ml) and Group F (n = 10) in which saline was used instead of anesthetic. The filling of the LTA kit (Abbott) was made by a person not involved in the experiments. DATA ANALYSIS: Student's t test for unpaired data. RESULTS: Topical anaesthesia reduces the increase of intraocular pressure, hypertension and rate pressure product due to intubation. The intraocular pressure reduces to 13% less than basal value in Group L and increase to 50% more than basal value in Group F. CONCLUSION: The topical anaesthesia of larynx and trachea is effective to reduce the intraocular hypertension due to the reflex response evoked by orotracheal intubation.     

Urokinase and the intestinal mucosa: evidence for a role in epithelial cell turnover

The enzyme nitric oxide synthase catalyzes the oxidation of the amino acid L-arginine to L-citrulline and nitric oxide in an NADPH-dependent reaction. Nitric oxide plays a critical role in signal transduction pathways in the cardiovascular and nervous systems and is a key component of the cytostatic/cytotoxic function of the immune system. Characterization of nitric oxide synthase substrates and cofactors has outlined the broad details of the overall reaction and suggested possibilities for chemical steps in the reaction; however, the molecular details of the reaction mechanism are still poorly understood. Recent evidence suggests a role for the reduced bound pterin in the first step of the reaction--the hydroxylation of L-arginine.     

Maturation of peroxisomes in differentiating human hepatoblastoma cells (HepG2): possible involvement of the peroxisome proliferator-activated receptor alpha (PPAR alpha)

Although several variant alleles at the human NAT1 gene locus have been reported, their relationship to phenotypic variations in NAT1 function remains unclear. We have used in-vivo and invitro phenotyping tests, along with PCR-based cloning and heterologous expression, to investigate the extent of variation in NAT1 function and to characterize novel allelic variants at the NAT1 gene locus. The NAT1-selective substrate p-aminosalicylic acid (PAS) was used as a probe for NAT1 function. In-vivo PAS acetylation rates were estimated by determining the ratio of PAS to N-acetylated PAS (AcPAS) in urine and plasma following the oral ingestion of Nemasol Sodium. Excluding outliers, a 65-fold variation in the urinary AcPAS:PAS ratio was observed (n = 144), while a 5.6-fold variation in the plasma AcPAS:PAS ratio was seen in a subset (n = 19) of this sample. Urinary and plasma ratios correlated moderately (r = 0.74, p < 0.0005). One individual (case 244) had a marked impairment of PAS N-acetylation, with 10-fold lower urinary and plasma AcPAS:PAS ratios compared with other subjects. Biochemical investigations in whole blood lysates from case 244 suggested a NAT1 kinetic defect, with a 20-fold increased apparent K(m) for PAS and a 90-fold decreased Vmax for AcPAS formation. We subcloned, sequenced and expressed the protein-coding regions of the NAT1 alleles from case 244 and from seven other selected probands. Sequence analysis revealed the presence of two new variant alleles, designated as NAT1 x 14 and NAT1 x 15, in case 244, as well as one variant, NAT1 x 11, which has been observed in previous investigations. NAT1 x 14 contained a missense mutation (G560-->A) that is predicted to change a single amino acid (Arg187-->Gln), as well as two 3' non-coding region mutations (T1088-->A and C1095-->A) that have previously been observed in the NAT1 x 10 allelic variant. NAT1 x 15 had a single nonsense mutation (C559-->T; Arg187-->stop) and, thus, encodes a truncated protein. The activity of recombinant NAT1 14 mirrored the defective enzyme function in whole blood lysates from case 244, while NAT1 15 was completely inactive. Expressed NAT1 11, on the other hand, had identical activity to the wild type NAT1 4 allele, suggesting that the coding region mutations in this variant are functionally silent. The frequencies of NAT1 x 11, NAT1 x 14 and NAT1 x 15 were 0.021, 0.028 and 0.014 (n = 288 alleles), respectively, suggesting that they are relatively rare in our predominantly Caucasian sample.     

Protection and advocacy system standing--to vindicate the rights of persons with disabilities

A characteristic of perinatal encephalopathies are the distinct patterns of neuronal and glial cell loss. Cerebral hypoperfusion is thought to be a major cause of these lesions. Gestational age is likely to influence outcome. This study compares the cortical electrophysiologic and histopathologic responses to hypoperfusion injury between preterm and near term fetuses. Chronically instrumented 0.65 (93-99-d, n = 9) and 0.9 (119-133-d, n = 6) gestation fetal sheep underwent 30 min of cerebral hypoperfusion injury. The parasagittal cortical EEG and impedance (measure of cytotoxic edema) responses plus histologic outcome (3 d) were compared. The acute rise in impedance was similar in amplitude, but the onset was delayed (5.0 +/- 0.7 versus 9.1 +/- 1.1 min, p < 0.05) in the preterm fetuses relative to those near term. In contrast the extent of the secondary rise was reduced (p < 0.01) and peaked earlier in the preterm fetuses (19.8 +/- 1.0 versus 40.5 +/- 3.5 h, p < 0.01). Both groups had a similar fall in EEG spectral edge frequency. The preterm fetuses had a milder loss of EEG intensity at 72 h (-7.7 +/- 1.5 versus -12.8 +/- 0.9 dB, p < 0.05). At both ages there was a predominantly parasagittal cortical distribution of damage with a similar pattern of neuronal loss in the thalamus and striatum. There was extensive selective neuronal loss within the upper layers of the cortex in those near term. In contrast the preterm fetuses developed subcortical infarcts (p < 0.05). The cortical response to injury altered during the last trimester. The results suggest the severity of the delayed phase of cortical neuronal injury and selective neuronal loss increased near term. In contrast, the preterm fetuses had a more rapidly evolving injury leading to necrosis of the subcortical white matter.     

Paracrine expression of a native soluble vascular endothelial growth factor receptor inhibits tumor growth, metastasis, and mortality rate

Vascular endothelial growth factor (VEGF) is a potent and selective vascular endothelial cell mitogen and angiogenic factor. VEGF expression is elevated in a wide variety of solid tumors and is thought to support their growth by enhancing tumor neovascularization. To block VEGF-dependent angiogenesis, tumor cells were transfected with cDNA encoding the native soluble FLT-1 (sFLT-1) truncated VEGF receptor which can function both by sequestering VEGF and, in a dominant negative fashion, by forming inactive heterodimers with membrane-spanning VEGF receptors. Transient transfection of HT-1080 human fibrosarcoma cells with a gene encoding sFLT-1 significantly inhibited their implantation and growth in the lungs of nude mice following i.v. injection and their growth as nodules from cells injected s.c. High sFLT-1 expressing stably transfected HT-1080 clones grew even slower as s.c. tumors. Finally, survival was significantly prolonged in mice injected intracranially with human glioblastoma cells stably transfected with the sflt-1 gene. The ability of sFLT-1 protein to inhibit tumor growth is presumably attributable to its paracrine inhibition of tumor angiogenesis in vivo, since it did not affect tumor cell mitogenesis in vitro. These results not only support VEGF receptors as antiangiogenic targets but also demonstrate that sflt-1 gene therapy might be a feasible approach for inhibiting tumor angiogenesis and growth.     

D1 and D2 dopamine receptor mediation of amphetamine-induced acetylcholine release in nucleus accumbens

To assess the interaction of dopamine and acetylcholine systems in the rat nucleus accumbens in response to direct D-amphetamine administration, in vivo microdialysis measures of acetylcholine were used during reverse dialysis of amphetamine alone and in combination with D1 and D2 receptor antagonists SCH 23390 and sulpiride, respectively. During a 15-min exposure to amphetamine (50 microM) in the nucleus accumbens, acetylcholine increased to 33% above pre-infusion levels, became maximal at 15 min post-infusion (+41%) and gradually returned to baseline levels by 60 min post-amphetamine. Conversely, amphetamine (1 mM) administration caused a biphasic change in acetylcholine release with a trend toward a decrease (-14%) during exposure followed by a significant increase (+36%) at 30 min post-amphetamine that returned to baseline levels by 60 min after infusion. The increases observed during amphetamine (50 microM) exposure and during recovery from amphetamine (1 mM) were both blocked by co-administration with the D1 antagonist, SCH 23390 (10 microM), but not with the D2 antagonist, sulpiride (10 microM). Co-infusion of sulpiride eliminated the trend toward reduced acetylcholine release observed during 1 mM amphetamine whereas co-administration of SCH 23390 potentiated this decrease. A possible tonic D1 facilitation of nucleus accumbens acetylcholine release was indicated by the consistent reductions in acetylcholine release observed during infusion of SCH 23390. These results suggest that amphetamine administration in the nucleus accumbens induces a bidirectional change in acetylcholine release that is dependent on dose and opposing effects of nucleus accumbens D1 and D2 activation. In general, relatively low doses of amphetamine administered into the nucleus accumbens caused an increase in acetylcholine release that was dependent on dopamine D1 receptors whereas higher doses of amphetamine resulted in a D2-mediated decrease.