Tumors of childhood in Ibadan, Nigeria (1973-1990)

Childhood neoplasms provide a fertile field for epidemiological research and afford a unique opportunity for studying possible mechanisms of carcinogenesis. The present study reviews 1881 malignant childhood neoplasms in children less than 15 years of age seen in the University College Hospital, Ibadan during an 18-year period. The male-to-female ratio was 1.4:1 and modal age of occurrence was 10 years. The most common childhood neoplasms were lymphomas (45.4%), retinoblastomas (9.7%), and malignant renal neoplasms (8.5%). Burkitt's lymphoma constituted 92% of all lymphomas and 37% of all childhood tumors. Comparison of two clinicopathological studies of childhood cancer in Ibadan between 1960-1972 and 1973-1990 revealed a dramatic upsurge in the relative frequencies of intracranial neoplasms, leukemias, renal neoplasms, and retinoblastomas, with a decline in the relative frequencies of bone neoplasms and Burkitt's lymphoma during the latter period. Whether these changes reflect actual changes in the distribution of childhood cancer in the local population will require further study.     

Organ injury scaling: spleen and liver (1994 revision)

A case of haemangiopericytoma of the greater omentum is reported here. We discuss the presentation, treatment and prognosis of these rare tumours.     

Pharmacological modulation of endothelial function by insulin in the rat aorta

The aim of this study was to investigate the transdermal iontophoresis of a newly designed capsaicin derivative, sodium nonivamide propionate (SNP). The iontophoretic permeation of SNP from various pH buffers increased following the decrease of pH values. This trend was consistent with that of sodium nonivamide acetate (SNA) which is another synthetic analogue of capsaicin. However, the iontophoretic permeability of SNP was much lower than that of SNA. SNP was also delivered iontophoretically from hydrogel formulations. It is suggested that ionizable polymers should be avoided for iontophoretic delivery to maintain good penetration capacity of drugs. Both nonionic cellulose polymers of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) showed higher iontophoretic flux for SNP than the others did. Furthermore, the flux of SNP leveled off with an increase in the amount of polymers in hydrogel, indicating that the viscosity of vehicles plays an important role in the permeation of SNP. Comparing the various iontophoretic application modes, the discontinuous on/off cyclic mode showed higher penetration capacity than did the continuous mode although they possessed the same electrical energy. Moreover, the desorption time of SNP from skin was approximately 20 min which was longer than that of SNA.     

Quantification of the nucleocytoplasmic distribution of wild type and modified proteins using confocal microscopy: interaction between 90-kDa heat shock protein (Hsp90 alpha) and glucocorticosteroid receptor (GR)

Elastin is a major protein component of the vascular wall and is responsible for its unusual elastic properties. Polymers of its repeating VPGVG sequences have been synthesised and shown to exhibit an inverse temperature transition where, as temperature rises, the polymer collapses from an extended chain to a beta-spiral structure with three VPGVG units per turn, each pentamer adopting a type II beta-turn conformation. These studies, however, have not established whether the temperature-driven conformational change is an intrinsic property of the individual pentameric sequences or a global, co-operative effect of many pentamers within the beta-spiral structure. Here, we examine by circular dichroism the behaviour of elastin-like peptides (VPGVG)n, where n varies between 1 and 5. Remarkably, we find that all lengths of peptide undergo an extended left and right arrow beta-turn transition with increasing temperature, suggesting that the induction of the beta-spiral occurs at the level of single pentameric units. The origin of this effect is a positive DeltaS term for the transition. At 35 degreesC, the average transition midpoint temperature, the value of TDeltaS is about 15 kcal mol-1. With larger oligomers (n=3), there is only a modest rise in DeltaS, suggesting that the dominant entropic effect resides within the monomer and that interactions between these units make only a small contribution to the energetics of the transition. Charges at the termini, and residue replacements or additions, regulate the transitions for the short peptides in a manner similar to that observed for the longer polymers. The behaviour of the same peptides in trifluoroethanol and SDS solutions is consistent with formation of the beta-turn being driven by interactions between non-polar groups. The significance of this behaviour for the rational design of temperature-induced responses in proteins is discussed.     

Malondialdehyde and 4-hydroxy-2-nonenal in plant tissue cultures: LC-MS determination of 2,4-dinitrophenylhydrazone derivatives

The cytologically active secondary lipid peroxidation products, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE) have been detected as their 2,4-dinitrophenylhydrazone (DNP) derivatives in plant tissue cultures using LC-MS. This paper reports, for the first time, the use of LC-MS methodology to definitively identify 4-hydroxy-2-nonenal in plants. Limits of detection for the two derivatives are approximately 5 pmol (1.2 x 10(-9) g; 1 microM) and 0.1 pmol (3 x 10(-11) g; 20 nM) respectively. Mass spectrometer response was linear in the range from 2-200 microM DNP-MDA and 0.02-10 microM DNP-HNE. This methodology has been used to assess the formation of aldehydic secondary lipid peroxidation products in dedifferentiated callus cultures of Daucus carota. The finding that profiles of MDA and HNE can be correlated with embryogenic competence is of considerable interest as oxidative status has already been implicated as a regulatory factor in animal development.     

Disparate effects of antidiabetic drugs on arterial contraction

Type II diabetic patients and others with insulin resistance are at risk for development of hypertension characterized by elevated peripheral vascular resistance and loss of insulin's normal vasodilating activity. Oral antidiabetic drugs have recently been recognized to have disparate effects on arterial pressure in such patients and in related rodent models. Sulfonylureas (e.g., glyburide), which stimulate insulin secretion, have been reported either to increase or not to affect arterial pressure, whereas nonsulfonylurea agents with insulin-sensitizing properties, the biguanide metformin and various thiazolidinediones (eg, pioglitazone), have been reported to decrease arterial pressure in humans and rodents. To help elucidate these disparate effects, we investigated these agents for direct actions on arterial vascular contractility and its sensitivity to insulin. Preincubation of intact rat tail arterial tissue rings for 2 hours with known therapeutically effective antidiabetic concentrations of metformin and pioglitazone significantly attenuated the force of contractions produced by either potassium (membrane depolarization) or norepinephrine ([NE] adrenergic receptor activation). Glyburide did not influence these contractions. Preincubation with metformin also induced an attenuating (vasodilating-like) action of insulin on arterial tissue rings contracted by potassium. Conversely, glyburide induced an accentuating action of insulin on potassium-mediated contractions. These results are consistent with measures of vascular function obtained in the past after oral administration of the drugs, which suggested but did not prove that they may exert direct effects on arterial vascular contractility. Thus, metformin and thiazolidinediones may decrease arterial pressure partly by direct vasorelaxant mechanisms, with metformin having an additional effect of inducing vasorelaxation by insulin. In contrast, sulfonylureas may directly induce a paradoxical vasoconstrictor response to insulin.     

Fourier-transform Raman spectra of ivory. III: Identification of mammalian specimens

The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.     

Radiographic sizing for meniscal transplantation

Allograft or synthetic meniscal replacement has the potential to delay the arthritic sequelae of the meniscectomized knee. Meniscal implants must, however, be side and size specific. A cadaveric study was performed in which medial and lateral menisci were painted with a radiopaque tantalum powder-cyanoacrylic mixture. Radiographs of this preparation demonstrated reproducible relationships between each meniscus and established bony landmarks. When corrected for magnification, meniscal size could be derived from plain films. Meniscal width equaled the distance (coronal) from the peak of the tibial eminence to the periphery of the tibial metaphysis on anteroposterior films. Meniscal length was measured from lateral radiographs. Medial meniscal length was 80%, and lateral meniscal length was 70% of the measured sagittal length of the tibial plateau. Measurement error averaged 7.8% by these parameters.     

Expression of fmrfamide gene neuropeptides is partly different in the embryonic nervous system of the pond snail, Lymnaea stagnalis L

The prevalence of hypercalcemia in patients with untreated tuberculosis (TB) varies widely between countries. Since the vitamin D status and calcium intake are important determinants of hypercalcemia in TB, these two factors were compared among four populations (U.K., Hong Kong, Malaysia, Thailand) with a low prevalence (<3%) and two populations (Sweden, Australia) with a high prevalence (>25%). In the three Asian countries, the circulating vitamin D levels are abundant, but the calcium intakes are low. Subjects from the U.K. have the lowest circulating vitamin D level of all, although their calcium intake is high. In Sweden and Australia, both the circulating vitamin D levels and calcium intakes are high. Since serum 1,25(OH)2D concentration will only be raised if its substance for extrarenal conversion, 25(OH)D, is plentiful and the effect of a given serum 1,25 (OH)2D concentration on serum calcium is determined by the calcium intake, it is postulated that the regional variation in the prevalence of hypercalcemia in TB may be due to differences in the circulating vitamin D levels and calcium intakes in these populations.