Studies on nitrogen cycling under different nitrogen inputs in integrated rice-fish culture in Bangladesh

Management of nitrogen (N) in rice-fish culture is of great significance in order to exploit synergies between rice and fish. However, detailed and systematic studies on N cycling in rice-fish systems are rare. An experiment was carried out at the Bangladesh Agricultural University using the fish species common carp, Cyprinus carpio L., and Nile tilapia, Oreochromis niloticus (L.). Efficiencies of fertilizer and feed as N inputs were evaluated by establishing an apparent N balance. The different N input strategies for rice-fish (RF) treatments were: (1) with fish, with urea (101 kg N ha⁻¹, RF Urea), (2) with fish, with feed (22.6 kg N ha⁻¹, RF Feed I), and (3) with fish, with feed (41.5 kg N ha⁻¹, RF Feed II). Rice only (var. BR28) with urea (101.2 kg N ha⁻¹) was added as the control (Rice only). Urea as N input (Rice only, RF Urea) resulted in negative apparent N balances (N output–N input), whereas N input in the form of feed (RF Feed I, RF Feed II) led to positive apparent N balances due to the lower N input. The presence of fish increased the grain and straw N output in RF Urea compared to Rice only, the effect being significant for straw (P < 0.05). Moreover, a significant difference in nitrogen uptake by rice was seen between the two feeding levels. The higher feeding rate in the RF Feed II treatment led to higher N outputs of grain, straw and fish compared to the RF Feed I treatment, a significant difference occurring for straw (P < 0.05). An apparent recovery efficiency of 48.7% was determined for the additional N input in RF Feed II compared to the RF Feed I teatment. An economic analysis revealed that the RF Urea treatment was the most profitable, as reflected by the highest gross margin. In conclusion, the results indicate that fish can improve nitrogen uptake by rice plants. Moreover, the supply of supplementary feed has a fertilizing effect on the rice due to the utilization of excreted feed nutrients by rice plants.     

Vascular superoxide dismutase deficiency impairs endothelial vasodilator function through direct inactivation of nitric oxide and increased lipid peroxidation

Nitric oxide (NO) and superoxide are both constitutive products of the endothelium. Because NO is readily inactivated by superoxide, the bioactivity of endothelium-derived NO (EDNO) is dependent on local activity of superoxide dismutase (SOD). We examined the effects of chronic inhibition of copper-zinc SOD (CuZnSOD) using a rat model of dietary copper restriction. Male weanling Sprague-Dawley rats were fed a Cu-deficient diet and received either no Cu replacement (Cu-deficient) or Cu in the drinking water (Cu-sufficient). Compared with Cu-sufficient animals, Cu-deficiency was associated with a 68% reduction in CuZnSOD activity and a 58% increase in vascular superoxide as estimated by lucigenin chemiluminescence (both P < .05). Compared with Cu-sufficient animals, arterial relaxation in the thoracic aorta from Cu-deficient animals was 10-fold less sensitive to acetylcholine, a receptor-dependent EDNO agonist, but only 1.5-fold less sensitive to A23187, a receptor-independent EDNO agonist, and only 1.25-fold less sensitive to authentic NO (all P < .05). In contrast, acute inhibition of CuZnSOD with 10 mM diethyldithiocarbamate produced a more uniform reduction in sensitivity to acetylcholine (8-fold), A23187 (10-fold), and NO (4-fold; all P < .001). Cu-deficient animals demonstrated a 2.5-fold increase in plasma-esterified F2-isoprostanes, a stable marker of lipid peroxidation, that correlated inversely with arterial relaxation to acetylcholine (R = -.83; P < .0009) but not A23187 or authentic NO. From these findings, we conclude that chronic inhibition of CuZnSOD inhibits EDNO-mediated arterial relaxation through two mechanisms, one being direct inactivation of NO and the other being lipid peroxidation that preferentially interrupts receptor-mediated stimulation of EDNO.     

High-dose multimodality therapy with autologous stem-cell support for stage IIIB breast carcinoma

PURPOSE: Women with locally unresectable and inflammatory breast carcinoma (IBC) have an approximately 30% 5-year disease-free survival (DFS) rate with conventional multimodality therapy. A short but dose-intensive multimodality phase II trial was designed in an attempt to improve outcome in stage IIIB disease. Mastectomy was performed after high-dose therapy to evaluate pathologic response to treatment. METHODS: Women with newly diagnosed disease received four 2-week cycles of doxorubicin 90 mg/m2 with granulocyte colony-stimulating factor (G-CSF), followed by cyclophosphamide 6,000 mg/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 (CTCb) with marrow and peripheral-blood progenitor cell (PBPC) support. Local therapy consisted of mastectomy and radiotherapy. Tamoxifen (5 years) was begun if the patient was estrogen receptor-positive (ER+). RESULTS: Fifty women (46 stage IIIB [91% IBC], four stage IIIA) entered the study and 47 are assessable. Ten had mastectomy before any systemic therapy (seven with pathologic IBC, three with residual tumor after mastectomy). Eighty percent received full-dose doxorubicin with 60% on schedule. Clinical response rates to induction were 15% complete response (CR), 5% very good partial response (VGPR), 59% partial response (PR), and 21% minor response (MR)/stable disease (SD). Mastectomy after CTCb in 37 patients showed a 14% pathologic CR rate, 29% microscopic foci in breast and/or axilla, and 57% gross tumor. Fifteen (32%) patients have relapsed (median, 17 months post-CTCb). The 30-month DFS is estimated at 64%. For those in pathologic CR, with microscopic, or with gross disease remaining after CTCb, the 30-month DFS is estimated at 100%, 70%, and 38%, respectively. Those with zero, one to three, or > or = four positive nodes at axillary dissection had a median DFS of 31, 18, and 13 months, respectively. CONCLUSION: This short but dose-intensive multimodality approach for stage IIIB breast carcinoma is feasible with encouraging results to date.     

Chronic, low-level (1.0 W/kg) exposure of mice prone to mammary cancer to 2450 MHz microwaves

In a previous study (Frei et al., Bioelectromagnetics 19, 20-31, 1998), we showed that low-level (0.3 W/kg), long-term exposure of mice prone to mammary tumors to 2450 MHz radiofrequency (RF) radiation did not affect the incidence of mammary tumors, latency to tumor onset, tumor growth rate or animal survival when compared to sham-irradiated animals. In the current study, the specific absorption rate (SAR) was increased from 0.3 W/kg to 1.0 W/kg. The same biological end points were used. One hundred C3H/HeJ mice were exposed in circularly polarized waveguides for 78 weeks (20 h/day, 7 days/week) to continuous-wave, 2450 MHz RF radiation; 100 mice were sham-exposed. There was no significant difference between exposed and sham-exposed groups with respect to the incidence of palpated mammary tumors (sham-exposed = 30%; irradiated = 38%), latency to tumor onset (sham-exposed = 62.0 +/- 2.3 weeks; irradiated = 62.5 +/- 2.2 weeks) and rate of tumor growth. Histopathological evaluations revealed no significant difference in numbers of malignant, metastatic or benign neoplasms between the two groups. Thus long-term exposures of mice prone to mammary tumors to 2450 MHz RF radiation at SARs of 0.3 and 1.0 W/kg had no significant effects when compared to sham-irradiated animals.     

Global approach to the asthmatic patient

Changes in the graft-infiltrating cell population (GIC) induced by Class I MHC pretreatment were characterized using flow cytometric analysis. C3H mice received 10(7) EL4 cells intravenously 14 days prior to transplant with C57BL/10 (H-2b) hearts. Transplanted hearts were removed from six recipients in both groups at 4, 6, 9, 12, 15, and 21 days after transplantation. GICs were harvested and incubated with FITC-conjugated Lyt-1 and Lyt-2 and phycoerythrin-conjugated L3T4 monoclonal antibodies. The proportion of GICs which were Lyt-1, L3T4, or Lyt-2 positive was similar in both control and pretreated groups at all times posttransplant, and all three cell populations exhibited similar changes over the course of the study in both groups. At Post-transplant Day (PTD) 9, there were significantly more double-staining cells (L3T4+, Lyt2+) in the pretreated group than in the control group (8.58 +/- 2.49% vs 4.36 +/- 1.32%, P < 0.05). By PTD 15, the double-staining cells had increased in pretreated mice to 17.46 +/- 4.36% of the total GICs (P < 0.05). The percentage of GICs in EL4-pretreated mice which were Lyt-1- was significantly higher at all time points than the percentage of L3T4- or Lyt-2- cells, whereas in the control, these cell populations were equivalent, implying that in pretreated mice, cells are present which are L3T4+ or Lyt2+ but Lyt-1-.(ABSTRACT TRUNCATED AT 250 WORDS)     

PIK1, an essential phosphatidylinositol 4-kinase associated with the yeast nucleus

Transmission of mitogenic and developmental signals to intracellular targets is often mediated by inositol derivatives. Here we present the cloning and characterization of a gene from Saccharomyces cerevisiae, PIK1, encoding the enzyme that catalyses the first committed step in the production of the second messenger inositol-1,4,5-trisphosphate. PIK1 encodes a phosphatidylinositol 4-kinase (PI 4-kinase) essential for growth. Cells carrying PIK1 on a multicopy vector overexpress PI 4-kinase activity exclusively in a nuclear fraction, suggesting that PIK1 is part of a nuclear phosphoinositide cycle. Temperature-sensitive mutations, but not a null mutation, can be suppressed by high osmolarity or an elevated concentration of Ca2+. Conditional mutants have a cytokinesis defect as indicated by a uniform terminal phenotype of cells with large buds and fully divided nuclei. We suggest that PIK1 controls cytokinesis through the actin cytoskeleton.     

Thermoanalysis of the combined Fe3O4-reduction and CH4-reforming processes

The chemical equilibrium composition of the system Fe₃O₄ + 4CH₄, at 1300 K and 1 atm consists of solid Fe and a 2:1 gas mixture of H₂ and CO. Thermogravimetric (TG) analysis combined with gas Chromatographic measurements was conducted on the reduction of Fe₃O₄ (powder, 2-μm mean particle size) with 2.3, 5, 10, and 20 pct CH₄ in Ar, at 1273, 1373, 1473, and 1573 K. The reduction proceeded in two stages, from Fe₃O_{4 to FeO, and finally to Fe. CR}, conversion and H₂ yield increased with temperature, while the overall reaction rate increased with temperature and CH4 concentration. C (gr) deposition, due to the cracking of CR,, was observed. By applying a topochemical model for spherical particles of unchanging size, the reaction mechanism was found to be mostly controlled by gas boundary layer diffusion. The apparent activation energy reached a maximum at 30 pct reduction extent and decreased monotonically until completion. When compared with the results using instead either H₂ or CO as reducing gas, the reduction achieved completion faster using CH₄, at temperatures above 1373 K.