Lysosomal-mediated degradation of apoptotic thymocytes within thymic nurse cells

A thymic epithelial cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature alphabetaTCR(lo)CD4(+)CD8(+) thymocytes in vitro was used in long-term coincubation experiments to determine the ultimate fate of thymocytes that remained within intracytoplasmic vacuoles of thymic nurse cells (TNCs). In an earlier report, a subset of the population released from the TNC interaction was shown to mature to the alphabetaTCR(hi)CD69(hi) stage of development, while thymocytes that bided within the TNC cytoplasm died through the process of apoptosis. Here, we show the presence of both apoptotic and nonapoptotic thymocytes within the cytoplasm of freshly isolated TNCs as well as in tsTNC-1 cells in culture. A microscopic analysis revealed total degradation of the cytoplasmic apoptotic thymocyte population that remained in tsTNC-1 cells after an 8- to 10-h incubation period. A quantitative analysis showed an increase of cytoplasmic thymocyte degradation over time to almost 80% after 9 h of incubation. However, in the presence of bafilomycin A1, which is used to inhibit acidification of lysosomal vesicles, degradation of apoptotic thymocytes never reached 10%. These data suggest that lysosomes within TNCs play a role in the degradation of apoptotic thymocytes. We examined tsTNC-1 cells before the addition of thymocytes to cultures and found lysosomes to be clustered around the nucleus in the cytoplasm of TNCs. Shortly after the internalization event, apoptotic thymocytes move to the area of the cytoplasm containing lysosomes. Using the confocal microscope, we obtained evidence that shows the degradation event to be facilitated through the fusion of lysosomes with the specialized vacuoles within TNCs containing apoptotic cells.     

Evidence for the direct transfer of the carboxylate of N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) to generate 4-carboxy-5-aminoimidazole ribonucleotide catalyzed by Escherichia coli PurE, an N5-CAIR mutase

Formation of 4-carboxy-5-aminoimidazole ribonucleotide (CAIR) in the purine pathway in most prokaryotes requires ATP, HCO3-, aminoimidazole ribonucleotide (AIR), and the gene products PurK and PurE. PurK catalyzes the conversion of AIR to N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) in a reaction that requires both ATP and HCO3-. PurE catalyzes the unusual rearrangement of N5-CAIR to CAIR. To investigate the mechanism of this rearrangement, [4,7-13C]-N5-CAIR and [7-14C]-N5-CAIR were synthesized and separately incubated with PurE in the presence of ATP, aspartate, and 4-(N-succinocarboxamide)-5-aminoimidazole ribonucleotide (SAICAR) synthetase (PurC). The SAICAR produced was isolated and analyzed by NMR spectroscopy or scintillation counting, respectively. The PurC trapping of CAIR as SAICAR was required because of the reversibility of the PurE reaction. Results from both experiments reveal that the carboxylate group of the carbamate of N5-CAIR is transferred directly to generate CAIR without equilibration with CO2/HCO3- in solution. The mechanistic implications of these results relative to the PurE-only (CO2- and AIR-requiring) AIR carboxylases are discussed.     

Post-oil-spill fires at Ugbomro (Niger Delta): a new vista in soil-pollution studies

Reconnaissance of the post-oil-spill, fire-scourged site at Ugbomro, in the Niger Delta, was contingent upon the loud public outcry and galvanizing hue that ensued the widespread conflagration. Sampling was carried out by the grid technique, and fire-scourged soils and their unaffected controls were analyzed. Contrary to the 'celebrated' opinion of some that the fires improvised bush fallowing for cropping, the site had witnessed severe impoverishment as evidenced by the hitherto neglected insidious impact of such infernos on soil macronutrients. Alterations in physico-chemical properties (pH, conductivity, etc.) provided adequate bases for this conclusion, and offered broad explanations for the paucity of macronutrients in affected soils. For instance, a pH range of 3.1-3.8 hindered N2 fixation and other metabolic activities that enhance mineralization. Elaeis guineensis in a density of 3 stands/m2 at the control site was the only tree-form not charred beyond recognition.Against future fires, it is important to strengthen contingencies for more-expedient clean-up responses to oil spills to severe possibilities of in situ conflagrations. Nutrient supplementations, revegetation, and site surveillance should disengage the 'unsighted fingers' of sabotage. A careful husbandry of these measures might re-establish nutrient stability, and forestall future re-occurrence of such effacing incidents.     

Nucleotide-Dependent Isomerization of Glutamate Dehydrogenase in Relation to Total RNA Contents of Peanut

The physiological function of glutamate dehydrogenase (GDH) was investigated by treating germinating peanut (Arachis hypogaea L.) seeds with nucleoside triphosphate (NTP) solutions in order to alter the isoenzyme distribution patterns. The free nucleosides and nucleotides of the GTP-treated peanut were the highest [8.7 μmol g⁻¹(f.m.)], and they decreased through the ATP-treated peanut [5.8 μmol g⁻¹(f.m.)], and CTP-treated peanut [5.5 μmol g⁻¹(f.m.)], to the UTP-treated peanut [4.1 μmol g⁻¹(f.m.)]. The combination of 4 NTPs induced 20 % higher content of Pi [173 nmol g⁻¹(f.m.)] than in the control, but the combined ATP+UTP treatment induced the lowest (93.0 nmol g⁻¹(f.m.)] Pi. The 4 NTP treatment also induced the highest number of GDH isoenzymes (28) followed by the purine NTP treatments (15 to 20), but the pyrimidine NTP treatments and the combined purine + pyrimidine NTP treatments induced the lowest numbers (<15) of isoenzymes. The deamination/amination ratios were generally higher in the UTP (0.11), and CTP (0.06) treated peanuts than in the GTP (0.04), and ATP (0.07) treated peanuts. There were mutual relationships between higher numbers of GDH isoenzymes present in the GTP-, and ATP-treated peanuts and higher RNA (236.5 and 239.4 μg g⁻¹, respectively) contents on one hand, and between the lower numbers of isoenzymes in the CTP-, and UTP-treated peanuts and lower RNA (162.0 and 152.5 μg g⁻¹, respectively) contents. The recurrent relationships of the effects of the NTP treatments of peanut were UTP > ATP > CTP > GTP. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effects of highly active antiretroviral therapy on the serum levels of pro-inflammatory and anti-inflammatory cytokines in HIV infected subjects

Background

Cytokines play an important role in controlling the homeostasis of the immune system and infection with Human Immunodeficiency virus (HIV) leads to deregulated production of both pro- and anti-inflammatory cytokines. This study was designed to determine the effects of HIV and Highly Active Antiretroviral Therapy (HAART) on the levels of pro-and anti-inflammatory cytokines in HIV infected subjects.

Method

A total of 50 HIV infected and 50 HIV seronegative control participants were recruited for the study. The HIV infected subjects were recruited before commencement of antiretroviral therapy and were followed up for 12?months. Blood samples were collected at 3 different points: before initiation of therapy, 6?months into therapy and 12?months into therapy. Serum cytokines were analyzed using ELISA method while CD4+ T cells and viral load counts were measured using standard laboratory methods.

Result

The results showed that pro-inflammatory cytokines: Tumour necrosis factor-alpha (TNF-α), Interleukin-6 (IL-6) and anti-inflammatory cytokines Interleukin-4 (IL-4), Interleukin-10 (IL-10) and Transforming growth factor-beta (TGF-β) were significantly elevated in HIV infected subjects before commencement of therapy compared to 6?months and 12?months into therapy (P?<?0.01) and compared to control participants (P?<?0.01). TNF-α, TGF-beta remained significantly elevated even after 12?months of therapy compared to control participants (P?<?0.01), while IL-4, IL-6, and IL-10 showed no significant difference compared to control participants after 12?months of therapy (P?>?0.05). INF-γ was significantly reduced before commencement of therapy and after 12?months of therapy compared to control participants (P?<?0.05) respectively.

Conclusion

TNF-α and TGF-β remained significantly elevated even after 12?months of therapy, while IFN-γ remained significantly reduced after 12?months of therapy. Regulating these cytokines which were unresponsive to therapy could serve as a potential measure of therapy for HIV infected subjects. The positive effect of 12?months therapy on IL-4, IL-6 and IL-10 levels can be used to monitor disease prognosis during therapy especially in resource poor setting where regular viral load monitoring is unavailable.

     

Acute toxicity of the water-soluble fraction of spent lubricating oil on the African catfish Clarias gariepinus

Static tests were employed to assess the acute toxicity of the water-soluble fraction (WSF) of spent automotive lubricating oil (of mixed SAE grades) on Clarias gariepinus, a freshwater fish commonly cultured in Nigeria. Median lethal concentrations (LC50) of the WSF were found to decrease as a function of exposure time from 690+/-21 (after 24 h) to 513+/-58 mg/l (after 96 h). The characteristics of the WSF such as mean acidity (pH 6.6), turbidity (40 NTU), total dissolved solids (TDS; 40 mg/l) and significantly reduced (P<0.05) dissolved-oxygen (DO) values (1.44 mg/l) were not compliant with existing standards set for discharged effluents. The solubility of the detected straight-chain aliphatics ranked as C14>C16>C32>C18>C28; that of the simple aromatics was ortho-xylene>para-xylene; and that of the polyaromatic hydrocarbons (PAHs) was acenaphthylene>9H-fluorene>naphthalene>anthracene>phenanthrene>chrysene>benzo[k]fluoranthene>benzo[a]pyrene>benzo[b]fluoranthene, most of which being serious carcinogens. These oil constituents and the overall physico-chemical properties of the WSF are expected to act synergistically on the test organism (C. gariepinus), eliciting the quantal responses observed. The toxicity of the WSF points to the base constituent, oxidative degradation, and mechano-chemical reactions associated with aged crankcase oils. These oils, therefore, should definitely no longer be disposed into water streams or landscape, not even at sub-lethal concentrations, because of the inherent toxicity of their soluble fractions and the associated danger of bioaccumulation.     

Upstream Petroleum Degradation of Mangroves and Intertidal Shores: The Niger Delta Experience

This article was inspired by a field reconnaissance survey of outcrops along the Nembe‐Brass axis of the petroliferous Niger Delta. It reviews various tradeoffs of the impact of upstream petroleum (seismic and production) operations on the mangrove ecosystems in that region, the largest in Sub‐Saharan Africa. Mangroves and intertidal shores are considered critical to the economic well‐being of this region owing to the people's dual occupation in fishing and farming. The mangrove ecosystem provides a nutrient medium, which serves as a nursery and spawning ground for many fish species and other biota. Oil and gas activities might destroy these spawn areas, causing reduction in resource output and community pressure. Devegetation of the mangrove forest as a result of seismic delineation leaves the fragile soil exposed, unprotected, and susceptible to erosion. Again, loss of vegetation might discourage the natural role of plants in air purification (CO₂ utilization and O₂ production). The release of nutrients (organic N₂, NH₃, and NO$\rm{{_{3}^{-}}}$ ) and polyaromatic hydrocarbons (PAHs) to the environment, with the attendant increase in microbial load, increases biochemical O₂ demand (BOD) and depletes dissolved O₂ (DO) in H₂O to a level that is beyond the tolerance limit of organisms. This anoxic situation leads to asphyxiation and subsequent fish kill in affected areas. In order of increasing vulnerability, the mangroves and intertidal shores of the Niger Delta fall under categories 8 to 10 on the environmental sensitivity index (ESI) scale, which predisposes the areas to serious long‐term effects and clean‐up complexity. Thus, there is need to monitor mangrove systems and shoreline changes in the areas of considerable seismic and production activities, especially in the coastal Niger Delta, where pipeline corrosion due to salt intrusion into the swampy environment and ‘unsighted fingers’ of sabotage have increased the prevalence of oil spills.     

Petroleum industry effluents and other oxygen-demanding wastes in Niger Delta, Nigeria

In this article, we review the fundamental phenomenon of oxygenation within the overriding context of petroleum-industry effluents and the other oxygen demanding wastes in Niger Delta, Nigeria. Drill cuttings, drilling mud (fluids used to stimulate the production processes), and accidental discharges of crude petroleum constitute serious land and water pollution in the oil-bearing province. Effluents from other industrial establishments such as distilleries, pulp and paper mills, fertilizer plants, and breweries, as well as thermal effluents, plant nutrients (such as nitrates and phosphates), and eroded sediments have also contributed to the pollution of their surrounding environment. Since these wastes are oxygen-demanding in nature, their impact on the recipient environment can be reversed by the direct application of simple chemistry. The wastes can be reduced, particularly in natural bodies of water, by direct oxidation-reduction processes or simple chemical combinations, acid-base reactions, and solubility equilibria; these are pH- and temperature-dependent. A shift in pH and alkalinity affects the solubility equilibria of Na+, Cl-, SO(2-), NO3(-), HCO3(-), and PO4(3-), and other ions and compounds.