Silver Nanoparticles by PAMAM-Assisted Photochemical Reduction of Ag(+)

The photochemical synthesis of Ag(0) nanoparticles in the presence of amino- and carboxylate-terminated PAMAM dendrimers is reported. The formation of Ag(0) nanoparticles was followed spectrophotometrically and by transmission electron microscopy (TEM). According to TEM investigations Ag(0) nanoparticles with the average size of about 7 nm in diameter were produced. Based on the present investigation a possible mechanism for the Ag(0) nanoparticles formation is proposed. Copyright 2000 Academic Press.

Aldehyde bisulfite-toluidine blue (ABT) staining as a topo-optical reaction for demonstration of linear order of vicinal OH groups in biological structures

The aldehyde-bisulfite-toluidine blue reaction followed by poststaining stabilization with potassium ferricyanide (ABT) is described as a topo-optical, oriented staining reaction of the vicinal OH groups of complex carbohydrates in biological structures such as polysaccharides, glycoproteins and glycolipids. The birefringence as induced by the oriented dye binding as a result of ABT is indicative of linear order of the vicinal OH groups and, in turn, provides information on the ultrastructural pattern of carbohydrate moieties in biological substances, which pattern is often not demonstrable by other ultrastructural methods. The possibilities of this new approach to the ultrastructural analysis of complex carbohydrates with ABT in a great number of biological substances is demonstrated and its practical value in histopathology discussed.

Serum 25(OH)-vitamin D levels and bone metabolism in patients on maintenance hemodialysis

AIMS

An increasing amount of evidence suggests that 25-hydroxy vitamin D3 (25(OH)D3) may contribute to the bone health of patients with chronic kidney disease (CKD). The underlying vitamin D status of these patients, however, has often been neglected. In a cross-sectional study we assessed the association between vitamin D status and parathyroid function, bone turnover, bone mass and structure in patients on maintenance hemodialysis.

METHODS

69 patients on maintenance hemodialysis were assessed by bone densitometry (DEXA) and quantitative bone ultrasound (QUS). Serum 25-hydroxy vitamin D3 levels, serum markers of bone turnover and clinical data were tabulated.

RESULTS

A high prevalence of potentially significant vitamin D3 deficiency was found in this patient group: 59% of the patients had a 25(OH)D3 level below 20 nmol/l. There was a significant negative correlation between serum 25(OH)D3 levels and serum intact parathyroid hormone (iPTH) (r = -0.231, p < 0.05), and this association remained significant after controlling for potential covariables. Furthermore, we show here that serum 25(OH)D3 concentration is positively correlated with bone mineral density (BMD) measured at the radius (r = 0.424, p < 0.01). Finally, we show for the first time that 25(OH)D3 levels are significantly and independently correlated with broadband ultrasound attenuation (beta = 0.262, p < 0.05) measured with calcaneal quantitative bone ultrasound (QUS) in patients with chronic renal failure.

CONCLUSION

Vitamin D3 deficiency may contribute to the impaired bone health of patients on maintenance dialysis.

The effects of task comprehension on preschoolers' and adults' categorization choices

In experimental tasks in which subjects sort sets of objects with conflicting appearances and taxonomic relations, preschoolers often have been found to categorize according to appearance. The procedures used in past studies, however, may have biased preschoolers to attend to appearance instead of taxonomic relations. This possibility was examined in two experiments. In Experiment 1, children's preference for taxonomic- or appearance-based sorting was affected by both the training and the instructions they received. Adults in Experiment 1 were affected by instructions, but not by training. In Experiment 2 preschoolers sorted above chance according to the criterion for which they received training and instruction (taxonomic relations or appearance). Consistency data, children's justifications, and spontaneous labeling support the conclusions that training and instructions have a significant effect on children's preference to sort according to taxonomic relations or appearance, and that both criteria can be used systematically by children as young as four. Implications for task comprehension, flexibility, methodology, and education are discussed.

Interaction between iron(II) and hydroxamic acids: oxidation of iron(II) to iron(III) by desferrioxamine B under anaerobic conditions

Interaction between iron(II) and acetohydroxamic acid (Aha), alpha-alaninehydroxamic acid (alpha-Alaha), beta-alaninehydroxamic acid (beta-Alaha), hexanedioic acid bis(3-hydroxycarbamoyl-methyl)amide (Dha) or desferrioxamine B (DFB) under anaerobic conditions was studied by pH-metric and UV-Visible spectrophotometric methods. The stability constants of complexes formed with Aha, alpha-Alaha, beta-Alaha and Dha were calculated and turned out to be much lower than those of the corresponding iron(II) complexes. Stability constants of the iron(II)-hydroxamate complexes are compared with those of other divalent 3d-block metal ions and the Irving-Williams series of stabilities was found to be observed. Above pH 4, in the reactions between iron(II) and desferrioxamine B, the oxidation of the metal ion to iron(III) by the ligand was found. The overall reaction that resulted in the formation of the tris-hydroxamato complex [Fe(HDFB)]+ and monoamide derivative of DFB at pH 6 is: 2Fe2+ + 3H4DFB+ = 2[Fe(HDFB)]+ + H3DFB-monoamide+ + H2O + 4H+. Based on these results, the conclusion is that desferrioxamine B can uptake iron in iron(III) form under anaerobic conditions.

Synthesis and pharmacological evaluation of some new tetrahydroisoquinoline derivatives inhibiting dopamine uptake and/or possessing a dopaminomimetic property

As shown by structure-activity relationship studies in 8-(substituted-amino)-4-aryl-2-methyl-1,2,3,4-tetrahydroisoquinolines, the most important structural requirement for a marked antidepressant action is the presence of an ureido, (alkoxycarbonyl)amino, or [(alkylamino)acyl]amino group attached to the isoquinoline skeleton in position 8. In one of the biological tests a significant difference was found between 8-amino-4-phenyl-2-methyl-1,2,3,4-tetrahydroisoquinoline (nomifensine) and the new compounds synthesized. Nearly all compounds substituted in the amino group either decrease the spontaneous motility in mice or exert no effect on it. Two syntheses have been elaborated for the preparation of the compounds represented by the general formulas II-V where R1 = hydrogen, halogen, or methyl; Y = CONHR, OCOR, or CO(CH2)nNHR, in which R = alkyl or aralkyl or NHR = cyclic amine and n = 1-2. The syntheses start either from the corresponding 8-amino-4-aryl-2-methyl-1,2,3,4-tetrahydroisoquinolines or from the corresponding noncyclized amino alcohols. Of the compounds, 4-(p-chlorophenyl)-8-[(ethoxy-carbonyl)amino]-2-methyl-1,2,3,4- tetrahydroisoquinoline was found to possess the highest activity.

Evaluation of the Tensioday ambulatory blood pressure monitor according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation

BACKGROUND

The validation of ambulatory blood pressure monitoring devices is necessary to obtain information on their accuracy. The objective of the present study was to evaluate the accuracy of the Tensioday oscillometric ambulatory blood pressure monitor according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation (AAMI).

DESIGN

We followed the phases recommended by the British Hypertension Society protocol: before-use calibration, in-use assessment, after-use calibration, static device validation and report of the evaluation. However, we expanded on the protocol to accommodate features required by the AAMI.

METHOD

The accuracy of calibration of three Tensioday devices was tested before and after the in-use phase when each of three devices was performing 10 24 h sessions of ambulatory monitoring. As all three devices passed these phases, the accuracy of blood pressure measurement was tested in one arbitrarily selected device on 85 subjects for systolic and 85 for diastolic blood pressure values. This was done by comparing three sequential same-arm blood pressure readings obtained by the device with three readings obtained by two observers using standard mercury sphygmomanometer. The comparisons were carried out while resting in the seated, supine and standing positions for all subjects. The results were used to grade the performance of the device according to the British Hypertension Society protocol and to calculate the mean +/- standard deviation of the difference between the device and the observers, as required by the AAMI.

RESULTS

The Tensioday device achieved an overall grade of A for both the systolic and diastolic measurements, and had a mean difference compared with the observer-measured blood pressure of 1.4 +/- 5.3/1.0 +/- 4.7 mmHg, which satisfies the AAMI criteria for accuracy. The British Hypertension Society grading did not change when patients with low, medium, and high blood pressure were analysed separately. The AAMI accuracy criteria were fulfilled in the standing and lying positions as well.

CONCLUSION

On the basis of these results, the Tensioday ambulatory blood pressure monitoring device can be recommended for clinical use for ambulatory monitoring. The accuracy of the device needs, however, further testing in special situations, such as in pregnancy, in elderly patients and during exercise.

Depressed monocyte production of interleukin-1 and tumor necrosis factor-alpha in patients with alcoholic liver cirrhosis

Interleukin-1 and tumor necrosis factor-alpha activity by E. coli lipopolysaccharide-triggered monocytes were studied in patients with chronic alcoholic liver disease. Monocytes from cirrhotic patients were shown to have a significant reduction in IL-1 and TNF-a activity, compared with that from age- and sex-matched healthy controls. These findings indicate further immunoregulatory disturbances concerning alcoholic liver cirrhosis.

Primary spinal intramedullary malignant lymphoma. A case report

A rare case of primary malignant intramedullary lymphoma, localized in the cervical part of the spinal cord, is presented. The onset of clinical symptoms was associated with herpes zoster infection. Surgery led to the histological diagnosis. The clinical investigations excluded the presence of lymphoma in other sites in the central nervous system and in the extraneural organs. Postoperative irradiation and chemotherapy effected relict of neurological symptoms.

An adult case of metachromatic leukodystrophy. Light, polarization and electron microscopic study

The findings are described in an adult case of metachromatic leukodystrophy examined by light, polarization and electron microscopy. Symmetrical demyelination was found in the cerebral hemispheres, but was moderate in the cerebellum, brain stem and spinal cord. Early changes in myelin of peripheral nerves have been demonstrated by polarization microscopy. Various metachromatic structures have been described in glial cells and neurons by electron microscopy, indicating disturbances at different metabolic steps of lipid metabolism. There are minor but no essential ultrastructural differences in the disease of different ages.

The role of the tubulointerstitial changes in the prognosis of IgA glomerulonephritis

The authors investigated the tubulointerstitial changes (atrophic tubuli, interstitial fibrosis and round-cell infiltration) by two methods in renal biopsies from 56 patients with IgA glomerulonephritis. A statistically significant correlation was found to exist between the tubulointerstitial changes and serum creatinine level at the time of renal biopsy. A statistical significant correlation was also established between serum creatinine at the end of a period of 5 years of follow-up and tubulointerstitial changes. Their results suggest that severe tubulointerstitial lesions in IgA glomerulonephritis carry a poor prognosis.