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Biomedical subjects

R Guillen

Publications and source records attributed to R Guillen.

8 recordsLinked to original sources
PubMed2001

A study of quetiapine: efficacy and tolerability in psychotic adolescents.

OBJECTIVE: To study the effectiveness, safety, and tolerability of quetiapine in adolescents with psychotic disorders. METHODS: This study was an 8-week, open trial using quetiapine with 15 adolescents, ages 13-17 years, mean age 15.1 years, with a diagnosis of a psychotic disorder. Our primary instruments focused on psychotic symptomatology as measured by the Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression (CGI), Positive and Negative Syndrome Scale (PANSS), and the Young Mania Rating Scale (YMRS). Other measures included adverse events, clinical laboratory tests, vital signs, electrocardiogram (ECG), extrapyramidal (EPS) measures, and ophthalmologic examination. RESULTS: Quetiapine significantly reduced psychotic symptoms as measured by the BPRS, PANSS, YMRS, CGI, and CGI Severity of Illness scale. The average weight gain was 4.1 kg. After correction for expected weight gain, the mean weight gain over the 8-week period was 3.4 kg. Prolactin and cholesterol remained unchanged. Trends were found for a decrease in T4 and an increase in thyroid-stimulating hormone. Common adverse effects were somnolence, agitation, drowsiness, and headache. No significant findings were noted on repeat ECGs, EPS measures, or ophthalmic examination. The final average treatment dose was 467 mg/day (range 300-800 mg/day). CONCLUSIONS: Quetiapine is suggested to be effective treatment of youths with psychotic disorders and to have a favorable side-effect profile.

Adolescent↗
PubMed1996

Improved protocol for the formation of N-(p-nitrobenzyloxy)aminoalditol derivatives of oligosaccharides.

An improved procedure has been developed for the rapid derivatization of oligosaccharides with UV-detectable p-nitrobenzylhydroxylamine (PNB). The improved conditions used result in quantitative derivatization of neutral oligosaccharides. Sialylated oligosaccharides can also be quantitatively PNB-derivatized without detectable desialylation. Of the oligosaccharides tested, only the derivatization of oligogalactosyluronic acids was incomplete (yield approximately 70%). PNB-derivatization of tamarind seed xyloglucan oligosaccharides results in products with improved chromatographic properties during HPAEC. These PNB derivatives were also subjected to hydrophilic interaction chromatography (HILIC) and analyzed by on-line LC-MS. On-line LC-MS is readily usable with HILIC, as this chromatographic technique does not require salt-containing solvents. Approximately 10 pmol of a PNB-derivatized oligosaccharide can be identified and quantitated utilizing this method.

Carbohydrate Conformation↗
PubMed1993

Structural analysis of tamarind seed xyloglucan oligosaccharides using beta-galactosidase digestion and spectroscopic methods.

The borohydride-reduced forms (oligoglycosyl alditols) of two isomeric octasaccharides (Glc4Xyl3Gal) that are released from xyloglucans of various plant species upon treatment with a fungal endo-(1-->4)-beta-glucanase were isolated and structurally characterized. A mixture of oligosaccharides that is released from tamarind seed xyloglucan by the endo-(1-->4)-beta- glucanase was digested with a commercially available beta-galactosidase (Aspergillus niger). The beta-galactosidase selectively hydrolyzed the galactosyl residue of one of the two isomeric octasaccharides present in the mixture. A homogeneous preparation of the beta-galactosidase-resistant octasaccharide was prepared by high-resolution gel-permeation chromatography of the enzyme-digestion products. Spectroscopic characterization of the oligoglycosyl alditol prepared by reduction of this octasaccharide confirmed the previously proposed structure that had been based on analysis of the mixture of isomeric octasaccharides. The availability of large amounts of the pure, reduced octasaccharide and of a pure, reduced pentasaccharide (Glc3Xyl2) made it possible to completely assign their 1H and 13C NMR spectra. In addition, the borohydride-reduced form of the beta-D-galactosidase-susceptible octasaccharide isomer was purified by high pH anion-exchange chromatography of the endo-(1-->4)-beta-glucanase-released octasaccharides from rape-seed xyloglucan (no beta-galactosidase treatment), and its 1H and 13C NMR spectra were assigned. Additional correlations between specific structural features of xyloglucan oligoglycosyl alditols and the positions of specific resonances in their NMR spectra were deduced and added to the extensive list that we have compiled. The effects of recording the NMR spectra of the xyloglucan oligoglycosyl alditols in the presence of borate salts, which could lead to incorrect structural assignments, are also described.

Carbohydrate Conformation↗
PubMed1985

Kidney allograft biopsy: a valuable tool in assessing the diagnosis of acute rejection.

In order to determine the value of an isolated renal percutaneous biopsy in renal allografts with acute rejection, we studied 17 allograft nephrectomies, in which the histological degree of acute rejection of each of 30 Tru-cut cylinders, were compared with the histological degree of acute rejection diagnosed in 6 large fragments of each kidney considered as a whole. An accurate histological degree of acute rejection was made in 366 cylinders (71.8%). One hundred twenty-nine kidney cylinders (25.3%) were considered of a minor histological degree of acute rejection and 15 cylinders (2.9%) of a higher histological degree. We conclude that percutaneous renal allograft biopsy provides a representative picture of acute rejection histopathology but must be evaluated with other clinical and biochemical data for a correct clinical management.

Acute Disease↗