A standoff, focused-beam land mine radar

This paper describes a standoff, focused-beam, ground-penetrating radar (GPR) for detecting buried antipersonnel (AP) mines. The radar features a 1 to 6 GHz, pulsed stepped-frequency microwave source with hardware range gate, an ultrawide bandwidth feed antenna, and an offset parabolic reflector. A focused-beam, created by feeding the reflector from an offset position, reduces the surface clutter and improves the detection of buried mines. A processing technique based on spectral analysis (Prony method) is developed in an attempt to reduce surface clutter. Tests conducted at the Fort A.P. Hill countermine test lanes showed excellent detection capability for both metallic and nonmetallic mines     

Dietary practices of South African ultradistance runners

Training (T) and prerace (PR) dietary intakes of male and female athletes participating in a 90-km ultramarathon and the usual diets of matched, sedentary controls were investigated using 24-hr dietary records. Supplement use, mean weekly training distance, and race performance times were recorded. Macro- and micronutrient intakes were analyzed using computerized nutritional analysis programs. Total mean energy intake in the T and PR diets of the runners was 10.1 and 12.8 MJ in the men (n = 150) and 7.5 and 9.1 MJ in the women (n = 23). Mean relative contribution of CHO to the runners' total kilojoule intake increased from 50.0 and 49.5% in the T diets to 57.7 (p < .05; n = 153) and 56.4% (p < .05; n = 23) in the PR diets of male and female runners, respectively, and energy-boosting supplements were included in the PR diets of 48% of female and 59% of male runners. Seventy-eight percent of female and 62% of male runners used vitamin and mineral supplements in their T diets as opposed to 39% of female and 28% of male controls. No statistically significant relationship was found between total kilojoule, CHO, fat, protein, and selected micronutrient intake during the 3 days before the race and performance in the 90-km event in runners of homogenous training status and gender.     

A randomized trial of recombinant human interleukin-11 following autologous bone marrow transplantation with peripheral blood progenitor cell support in patients with breast cancer

Complications resulting from advanced atherosclerosis are the most common indication for vascular reconstructive surgery. Atherosclerosis is a systemic disease affecting the entire arterial tree, but lesions involving the coronary, extracranial cerebral, and lower extremity circulations have the most clinical significance for surgeons. The pathogenesis of atherosclerosis involves a complex series of events, similar to a chronic inflammatory process, with the formation of atherosclerotic plaque as the end result. Injury to the endothelial cell of the artery, resulting in endothelial cell dysfunction, is the first step in the process. Activated endothelial cells attract leukocytes and vascular smooth muscle cells (VSMC), which accumulate and proliferate in the arterial wall. These cellular components produce an excessive amount of connective tissue matrix. The ultimate end point is the formation of a mature fibrous plaque. Symptoms occur when advanced lesions are complicated by plaque rupture, hemorrhage into the plaque, emboli, or thrombosis. A thorough understanding of the pathogenesis of atherosclerosis is essential for the development of strategies for the prevention of the disease, and for the development of new and effective treatments.     

A pilot study on the effects of cultivation conditions of chicory (Cichorium intybus L.) roots on the levels of sesquiterpene lactones in chicons

 One of the quality parameters of chicory (Cichorium intybus L.) is its slightly bitter taste which is caused by sesquiterpene lactones. As the quality of chicons is highly dependent on the quality of the roots, the effects of the cultivation conditions of the roots on the levels of sesquiterpene lactones in chicons were investigated. Roots from a collection of 11 commercially available and 2 experimental chicory cultivars were grown at five different locations with two nitrogen manuring levels to evaluate the differences in sesquiterpene lactone levels as measured with enzyme-linked immunosorbent assays (ELISAs). There were significant differences (P<0.001) between cultivars in both lactucopicrin and lactucin-like (lactucin, 8-deoxylactucin and their 11β,13-dihydro derivatives) sesquiterpene lactone levels. In addition, a significant (P=0.006 and P=0.019, respectively) effect of additional nitrogen manuring was observed on the levels of lactucopicrin and lactucin-like sesquiterpene lactones. The interaction of cultivar with nitrogen manuring had a significant (P=0.013) effect on the level of lactucin-like sesquiterpene lactones. Furthermore, the lactucopicrin level was significantly influenced by the interactions of the cultivar with the nitrogen manuring level (P<0.001), with the location (P=0.001) and with both the nitrogen manuring level and location (P<0.001). The results indicate that it may be possible to influence the level of the bitter sesquiterpene lactones and, consequently, to influence the taste of chicons by cultivar choice and/or cultivation location and conditions. Received: 17 December 1996     

Modifications in the rhythm of schizogony in Plasmodium chabaudi chabaudi associated with the selection of chloroquine resistance

Thirty-two patients affected with skeletal conditions were examined with MRI using Short TI Inversion Recovery sequence and Spectral Presaturation with Inversion Recovery (SPIR) sequence as well as Spin-Echo (SE) T1-weighted sequence and Fast Spin-Echo (FSE) T2-weighted sequence to compare their value in the assessment of skeletal lesions. SPIR sequence was performed after intravenous injection of Gd-DTPA. The lesions included primary bone tumors (10 cases: 1 osteosarcoma, 1 periosteal sarcoma, 1 Ewing's sarcoma, 1 chondrosarcoma, 2 non-ossifying fibromas, 1 chondroma, 1 chondromyxoid fibroma, 1 desmoplastic fibroma and 1 bone cyst), metastases (7 cases: 3 prostate, 3 breast, 1 lung-squamous cell carcinoma), infections (12 cases: 9 osteomyelitis, 3 spondylodiscitis), sacroiliitis (1 case) and posttraumatic bone bruise (2 cases of bone marrow edema). The four sequences were compared by using both qualitative and quantitative evaluation. Qualitative evaluation showed that STIR sequence was better than SPIR sequence (performed with Gd-DTPA) for lesion conspicuity (p < .016) and for signal intensity uniformity (p < .03). Compared with SE T1 and FSE T2 sequences, fat-suppressed sequences were superior for conspicuity, margins, and extension of the lesions (range of p < .001-.017). Only SPIR with Gd-DTPA sequence, compared with SE T1 sequence for lesion conspicuity was not statistically significantly different. Quantitative evaluation showed statistically significant higher values of percent contrast (%C) and contrast-to-noise ratio (C/N) for STIR sequence compared with SPIR sequence (%C p < .004; C/N p < .040). This study suggests that STIR sequence and SE T1-weighted sequence provide high sensitivity in lesion detection and good anatomical definition. The use of a fat-suppressed sequence with Gd-DTPA can be useful for lesion characterization.     

Cytotoxicity and cell-proliferation induced by the nephrocarcinogen hydroquinone and its nephrotoxic metabolite 2,3,5-(tris-glutathion-S-yl)hydroquinone

Hydroquinone, an intermediate used in the chemical industry and a metabolite of benzene, is a nephrocarcinogen in the 2-year National Toxicology Program bioassay in male Fischer 344 rats. Current evidence suggests that certain chemicals may induce carcinogenesis by a mechanism involving cytotoxicity, followed by sustained regenerative hyperplasia and ultimately tumor formation. Glutathione (GSH) conjugates of a variety of hydroquinones are potent nephrotoxicants, and we now report on the effect of hydroquinone and 2,3,5-(tris-glutathion-S-yl)hydroquinone, on site-selective cytotoxicity and cell proliferation in rat kidney. Male Fischer 344 rats (160-200 g) were treated with hydroquinone (1.8 mmol/kg or 4.5 mmol/kg, p.o.) or 2,3,5-(tris-glutathion-S-yl)hydroquinone (7.5 micromol/kg; 1.2-1.5 micromol/rat, i.v.), and blood urea nitrogen (BUN), urinary gamma-glutamyl transpeptidase (gamma-GT), alkaline phosphatase (ALP), glutathione-S-transferase (GST) and glucose were measured as indices of nephrotoxicity. Hydroquinone (1.8 mmol/kg, p.o.) is nephrotoxic in some rats, but not others, but cell proliferation (BrDU incorporation) in proximal tubular cells of the S3M region correlates with the degree of toxicity in individual rats. At 4.5 mmol/kg, hydroquinone causes significant increases in the urinary excretion of gamma-GT, ALP and GST. Pretreatment of rats with acivicin prevents hydroquinone-mediated nephrotoxicity, indicating that toxicity is dependent on the formation of metabolites that require processing by gamma-GT. Consistent with this view, 2,3,5-(tris-glutathion-S-yl)hydroquinone, a metabolite of hydroquinone, causes increases in BUN, urinary gamma-GT and ALP, all of which are maximal 12 h after administration of 2,3,5-(tris-glutathion-S-yl)hydroquinone. In contrast, the maximal excretion of GST and glucose occurs after 24 h. By 72 h, BUN and glucose concentrations return to control levels, while gamma-GT, ALP and GST remain slightly elevated. Examination of kidney slices by light microscopy revealed the presence of tubular necrosis in the S3M segment of the proximal tubule, extending into the medullary rays. Cell proliferation rates in this region were 2.4, 6.9, 15.3 and 14.3% after 12, 24, 48 and 72 h, respectively, compared to 0.8-2.4% in vehicle controls. Together with the metabolic data, the results indicate a role for hydroquinone-thioether metabolites in hydroquinone toxicity and carcinogenicity.     

Identification of novel metabolites of butadiene monoepoxide in rats and mice

Differences in the metabolism of 1,3-butadiene (Bd) in rats and mice may account for the observed species difference in carcinogenicity. Previous studies of the metabolic fate of Bd have identified epoxide formation as a key metabolic transformation which gives 1, 2-epoxy-3-butene (BMO), although some evidence of aldehyde metabolites is reported. In this study, male Sprague-Dawley rats and male B6C3F1 mice received single doses of [4-14C]BMO at 1, 5, 20, and 50 mg/kg of body weight (0.014, 0.071, 0.286, and 0.714 mmol/kg of body weight). Analysis of urinary metabolites indicated that both species preferentially metabolize BMO by direct reaction with GSH when given by ip administration. The excretion of (R)-2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene (IIa), 1-(N-acetyl-L-cystein-S-yl)-2-(S)-hydroxybut-3-ene (IIb), 1-(N-acetyl-L-cystein-S-yl)-2-(R)-hydroxybut-3-ene (IIc), and (S)-2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene (IId) accounted for 48-64% of urinary radioactivity in rats and 46-54% in mice. The metabolites originating from the R-stereoisomer of BMO (IIc and IId) predominated over those arising from the S-stereoisomer (IIa and IIb) in both species. IIc was formed preferentially in mice and IId in rats. The corresponding mercaptoacetic acids, S-(1-hydroxybut-3-en-2-yl)mercaptoacetic acid (IIf) and S-(2-hydroxybut-3-en-1-yl)mercaptoacetic acid (IIg), were identified only in mouse urine (ca. 20% of the recovered radioactivity). 4-(N-Acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (Ia), a metabolite derived from hydrolysis of BMO, accounted for 10-17% of the radioactivity in rat and 6-10% in mouse urine. 4-(N-Acetyl-L-cystein-S-yl)-2-hydroxybutanoic acid (Ib), 3-(N-acetyl-L-cystein-S-yl)propan-1-ol (Ic), and 3-(N-acetyl-L-cystein-S-yl)propanoic acid (Id), also derived from the hydrolysis of BMO, were only present in the rat. Metabolites of 1,2,3,4-diepoxybutane (DEB) were not detected after administration of BMO in rat or mouse urine. This study showed both quantitative and qualitative differences in the metabolism of BMO with varying doses and between species. The data aid in the safety evaluation of Bd and contribute to the interpretation of mathematical models developed for quantitative risk assessment and extrapolation of animals to humans.     

Identification of a putative alpha-glucan synthase essential for cell wall construction and morphogenesis in fission yeast

The cell wall protects fungi against lysis and determines their cell shape. Alpha-glucan is a major carbohydrate component of the fungal cell wall, but its function is unknown and its synthase has remained elusive. Here, we describe a fission yeast gene, ags1(+), which encodes a putative alpha-glucan synthase. In contrast to the structure of other carbohydrate polymer synthases, the predicted Ags1 protein consists of two probable catalytic domains for alpha-glucan assembly, namely an intracellular domain for alpha-glucan synthesis and an extracellular domain speculated to cross-link or remodel alpha-glucan. In addition, the predicted Ags1 protein contains a multipass transmembrane domain that might contribute to transport of alpha-glucan across the membrane. Loss of Ags1p function in a temperature-sensitive mutant results in cell lysis, whereas mutant cells grown at the semipermissive temperature contain decreased levels of cell wall alpha-glucan and fail to maintain rod shapes, causing rounding of the cells. These findings demonstrate that alpha-glucan is essential for fission yeast morphogenesis.