Levodopa replacement therapy alters enzyme activities in striatum and neuropeptide content in striatal output regions of 6-hydroxydopamine lesioned rats

The effects of striatal dopamine denervation and levodopa replacement therapy on neuronal populations in the rat striatum were assessed by measurement of glutamic acid decarboxylase (GAD) and choline acetyltransferase (CAT) activities in the striatum, dynorphin and substance P concentrations in the substantia nigra, and enkephalin concentration in the globus pallidus. Rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal pathway were treated for 21 days with levodopa (100 mg/kg/day, i.p., with 25 mg/kg benserazide) on either an intermittent (b.i.d.) or continuous (osmotic pump infusion) regimen and sacrificed following a three day drug washout. In saline-treated control rats, striatal GAD activity and globus pallidus enkephalin content were elevated and nigral substance P content was reduced ipsilateral to the 6-OHDA lesion. Intermittent levodopa treatment further increased GAD activity, decreased CAT activity, restored substance P to control levels, markedly increased dynorphin content, and had no effect on enkephalin. In contrast, continuous levodopa elevated globus pallidus enkephalin beyond the levels occurring with denervation, but had no effect on any of the other neurochemical measures. These results indicate that striatal neuronal populations are differentially affected by chronic levodopa therapy and by the continuous or intermittent nature of the treatment regimen. With the exception of substance P, levodopa did not reverse the effects of the 6-OHDA lesion but, rather, either exacerbated the lesion-induced changes (e.g. GAD and enkephalin) or altered neurochemical markers which had been unaffected by the lesion (e.g. CAT and dynorphin).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of fatty acids on the mycelial growth and polysaccharide formation by Ganoderma lucidum in shake flask cultures

Fatty acids were added into the media to investigate their effects on the mycelial growth and polysaccharide formation by Ganoderma lucidum. The experiments were carried out in freely suspended cultures or immobilized cultures using shake flasks. The results indicate that the extent of stimulation or inhibition were associated with the types and levels of fatty acids. Oleic acid at the level of 0.15 g/100 ml led to a significant increase in cell concentration from 0.20 to 0.46 g/100 ml in a suspended culture and palmitic acid was of great advantage to polysaccharide production. In contrast, linoleic acid (0.1 g/100 ml) drastically suppressed both mycelial growth and polysaccharide formation. In immobilized cultures with fatty acids, the stimulation of mycelial growth remained the same level, but the enhancement of polysaccharide production became less. In addition, the growth of G. lucidum in the pattern of immobilization might be beneficial to the production of mycelia and polysaccharide.

Dopaminergic modulation of striatal neuropeptides: differential effects of D1 and D2 receptor stimulation on somatostatin, neuropeptide Y, neurotensin, dynorphin and enkephalin

Dopaminergic modulation of neuropeptides in rat striatum was investigated by examining the effects of prolonged D1 or D2 receptor stimulation on levels of somatostatin, neuropeptide Y, neurotensin, dynorphin and enkephalin. Rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal pathway were treated for 7 days with either the D1 agonist SKF 38393 (12.5 mg/kg/day) or the D2 agonist quinpirole (1 mg/kg/day). Two regimens of agonist treatment were compared: continuous infusion via osmotic pump implanted i.p. and intermittent (once daily) i.p. injection. Rats were sacrificed 3 h after the last injection and peptide levels measured in the striatum bilaterally by radioimmunoassay; alterations in peptide content were observed primarily in the denervated striatum. In comparison to values from lesioned, vehicle-treated controls, intermittent administration of SKF 38393 reduced somatostatin and neuropeptide Y (down 61% and 57%, respectively), increased neurotensin (up 105%) and dynorphin (up 184%) and had no effect on enkephalin; continuous SKF 38393 decreased neuropeptide Y by 39% but did not alter levels of the other peptides. Continuous quinpirole elevated somatostatin and neuropeptide Y levels (up 43% and 33%, respectively), but reduced the lesion-induced increases in both neurotensin (down 51%) and enkephalin (down 24%) content. Conversely, intermittent quinpirole decreased somatostatin (down 35%) and neuropeptide Y (down 27%), increased neurotensin content by 79% and had no effect on enkephalin. Dynorphin levels were not altered by either continuous or intermittent quinpirole. These findings reveal the complexity of dopaminergic influences on striatal neuropeptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of Pseudomonas aeruginosa to the phenotype characteristic of strains from patients with cystic fibrosis

Isolates of Pseudomonas aeruginosa from cystic fibrosis patients are unusual; they are often susceptible to the bactericidal effect of human serum, have a rough lipopolysaccharide, and produce an exopolysaccharide that is responsible for the characteristic mucoid phenotype. In contrast, strains from the environment and from patients with other diseases usually have smooth lipopolysaccharide, do not produce very much mucoid exopolysaccharide, and are phenotypically nonmucoid. The predominance of mucoid strains of P. aeruginosa in infections of patients with cystic fibrosis has not been explained. In the lower airways, where P. aeruginosa persists in cystic fibrosis, nutrients for bacterial growth may be limited. We investigated whether growth of P. aeruginosa under conditions of suboptimal nutrition causes conversion to the characteristic cystic fibrosis phenotype. Ninety-two strains of P. aeruginosa were maintained for up to 90 days in a minimal medium with acetamide as the sole carbon source. In 56 (52%) of 107 cultures, isolates with rough lipopolysaccharide emerged, and in 20 (19%) of 104 nonmucoid cultures, mucoid isolates were recovered. Strains with rough lipopolysaccharide also were sensitive to the bactericidal effect of normal human serum. Under conditions of suboptimal nutrition in vitro, isolates of P. aeruginosa emerged that produced rough lipopolysaccharide and were mucoid, typical of many isolates from cystic fibrosis patients. This peculiar phenotype may arise as a consequence of nutritional limitation within the cystic fibrosis respiratory tract rather than from features unique to these strains of bacteria.

Fresh green tea and gallic acid ameliorate oxidative stress in kainic acid-induced status epilepticus

Green tea is one of the most-consumed beverages due to its taste and antioxidative polyphenols. However, the protective effects of green tea and its constituent, gallic acid (GA), against kainic acid (KA)-induced seizure have not been studied. We investigated the effect of fresh green tea leaf (GTL) and GA on KA-induced neuronal injury in vivo and in vitro. The results showed that GTL and GA reduced the maximal seizure classes, predominant behavioral seizure patterns, and lipid peroxidation in male FVB mice with status epilepticus (SE). GTL extract and GA provided effective protection against KA-stressed PC12 cells in a dose-dependent manner. In the protective mechanism study, GTL and GA decreased Ca(2+) release, ROS, and lipid peroxidation from KA-stressed PC12 cells. Western blot results revealed that mitogen-activated protein kinases (MAPKs), RhoA, and COX-2 expression were increased in PC12 cells under KA stress, and expression of COX-2 and p38 MAPK, but not RhoA, was significantly reduced by GTL and GA. Furthermore, GTL and GA were able to reduce PGE(2) production from KA-stressed PC12 cells. Taken together, the results showed that GTL and GA provided neuroprotective effects against excitotoxins and may have a clinical application in epilepsy.

Propionic acid and its esterified derivative suppress the growth of methicillin-resistant Staphylococcus aureus USA300

Previously, we demonstrated that Propionibacterium acnes, a human skin commensal bacterium, ferments glycerol into short-chain fatty acids, including propionic acid. Propionic acid suppressed the growth of Staphylococcus aureus USA300, a community-acquired methicillin-resistant bacterium, in vitro and in vivo. In this study, it is demonstrated that the anti-USA300 activity of propionic acid persisted after buffering the acid with 4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid. This suggests that the growth suppression of USA300 mainly resulted from the antimicrobial activity of propionic acid per se and not from the acidity of the medium. In addition, proprionic acid significantly reduced the intracellular pH of USA300 and exhibited broad-spectrum antimicrobial activity against Escherichia coli and Candida albicans. P. acnes showed a higher tolerance to propionic acid. Next, an esterified derivative of propionic acid was synthesised. Propionic acid and the esterified derivative were equivalent in their efficacy to suppress the growth of USA300 in vitro. The esterified derivative thus provides an alternative to propionic acid as an antimicrobial agent against S. aureus.

Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated rice soils

Soil washing is considered a useful technique for remediating metal-contaminated soils. This study examined the release edges of Cd, Zn, Ni, Cr, Cu or Pb in two contaminated rice soils from central Taiwan. The concentrations exceeding the trigger levels established by the regulatory agency of Taiwan were Cu, Zn, Ni and Cr for the Ho-Mei soil and Pb for the Nan-Tou soil. Successive extractions with HCl ranging from 0 to 0.2 M showed increased release of the heavy metals with declining pH, and the threshold pH value below which a sharp increase in the releases of the heavy metals was highest for Cd, Zn, and Ni (pH 4.6 to 4.9), intermediate for Pb and Cu (3.1 to 3.8) and lowest for Fe (2.1), Al (2.2) and Cr (1.7) for the soils. The low response slope of Ni and Cr particularly for the rice soils make soil washing with the acid up to the highest concentration used ineffective to reduce their concentrations to below trigger levels. Although soil washing with 0.1 M HCl was moderately effective in reducing Cu, Pb, Zn and Cd, which brought pH of the soils to 1.1+/-0.1 (S.D.), the concurrent release of large quantities of Fe and Al make this remediation technique undesirable for the rice soils containing high clay. Successive washings with 0.01 M HCl could be considered an alternative as the dissolution of Fe and Al was minimal, and between 46 to 64% of Cd, Zn, and Cu for the Ho-Mei soil and 45% of Pb in the Na-Tou soil were extracted after four successive extractions with this dilute acid solution. The efficacy of Cd extraction improved if CaCl2 was added to the acid solution. The correlation analysis revealed that Cr extracted was highly correlated (P < 0.001) with Fe extracted, whereas the Cu, Ni, Zn, Cd or Pb extracted was better correlated (P < 0.001) with Al than with Fe extracted. It is possible that the past seasonal soil flooding and drainage in the soils for rice production was conducive to incorporating Cr within the structure of Fe oxide, thereby making them extremely insoluble even in 0.2 M HCl solution. The formation of solid solution of Ni with Al oxide was also possible, making it far less extractable than Cd, Zn, Cu, or Pb with the acid concentrations used.

Use of dynamic capillaroscopy for studying cutaneous microcirculation in patients with diabetes mellitus

To investigate the relationship between cutaneous microcirculation and retinopathy in diabetes mellitus, we studied by dynamic capillaroscopy 35 diabetes mellitus patients, including 10 patients without retinopathy, 10 patients with background retinopathy, and 15 patients with proliferative retinopathy. We found that (1) cutaneous and retinal microcirculation in diabetes mellitus in long-term diabetes mellitus, regressional rather than proliferational changes occurred in skin vasculature as compared to that in retina; (2) functional impairments of cutaneous microcirculation, that is, decreased resting capillary blood cell velocity, peak blood cell velocity, and prolonged time to peak capillary blood cell velocity by dynamic capillaroscopy, could be detected in diabetes mellitus patients without retinopathy; (3) the degree of tortouosity of capillaries, impairment in peak capillary blood cell velocity, and time to peak capillary blood cell velocity of cutaneous microcirculation were significantly correlated with the gravity of retinopathy in diabetes mellitus patients; (4) abnormal leakage of fluorescence in cutaneous microcirculation appeared in diabetes mellitus patients with or without abnormal fluorescein angiography in retina. In conclusion, dynamic capillaroscopy used in concert with ophthalmoscopy and fluorescein angiography can facilitate a comprehensive examination of vasculopathy in diabetes mellitus.

PCP-induced alterations in cerebral glucose utilization in rat brain: blockade by metaphit, a PCP-receptor-acylating agent

The effects of phencyclidine (PCP) on regional cerebral glucose utilization was determined by using quantitative autoradiography with [14C]-2-deoxyglucose. PCP increased brain metabolism in selected areas of cortex, particularly limbic, and in the basal ganglia and thalamus, whereas the drug decreased metabolism in areas related to audition. These results are consistent with the known physiology of central PCP neurons and may help to suggest brain areas involved in PCP-mediated actions. Moreover, based on the behavioral similarities between PCP psychosis and an acute schizophrenic episode, these data may be relevant to the understanding of schizophrenia. The PCP-receptor-acylating agent, metaphit, blocked most of these PCP actions. In addition, metaphit by itself was found to diminish glucose utilization rather uniformly throughout brain. These results indicate an antagonist effect of metaphit on the PCP system and suggest a widespread action of metaphit, putatively at a PCP-related site, possibly in connection with the N-methyl-D-aspartate (NMDA) receptor.

GABAA and GABAB receptors differentially regulate striatal acetylcholine release in vivo

Microdialysis was used to study the effects of selective GABAergic agents on striatal acetylcholine (ACh) release in awake, freely moving rats. Local perfusion with the GABAA agonist muscimol dramatically reduced striatal ACh release, while the GABAB agonist baclofen caused only minor decreases in ACh release. Co-perfusion with the GABAA antagonist bicuculline diminished the muscimol-induced decrease in ACh release. Likewise, co-perfusion with the GABAB antagonist 2-hydroxysaclofen attenuated the baclofen-induced reduction in ACh release. Bicuculline alone markedly increased striatal ACh release, but 2-hydroxysaclofen by itself had no effect. These results suggest that GABA tonically regulates striatal ACh release primarily through stimulation of inhibitory GABAA receptors.

Antibodies to Epstein-Barr virus-specific DNase in patients with nasopharyngeal carcinoma and control groups

Serum samples from 154 patients with nasopharyngeal carcinoma (NPC), 374 with other cancers, 1,000 normal controls from Government Employees' Clinic Center (GECC), and 3,642 individuals of various ethnic-dialect groups living in high-risk areas for NPC were collected and the concentration of antibodies to Epstein-Barr virus (EBV)-specific DNase activity was determined. Taking a serum sample where 1 ml will neutralize two or more units of the DNase activity as positive, 2-4 units as low level, 4-6 units as medium level, and more than 6 units as a high level of antibody, 90.3% of the NPC patients contained significant amounts of antibodies to EBV-specific DNase activity and most of those had high levels of the antibody. In contrast, only 11% of sera from patients with cancers other than NPC contained antibodies to EBV-specific DNase activity, and high levels were very rare (2.1%). The difference in positive rates between these two groups is highly significant according to the chi 2 test (P less than 0.001). The positive rate of this antibody in the control group (GECC) was 5.3% with 0.0%, 0.8%, and 4.5% having high, medium, and low levels of antibodies, respectively. Again, the difference in positive rates between the GECC group and the NPC group is statistically significant (P less than 0.001). Taken separately, the positive rates of anti-EBV DNase activity in the three high-risk groups were 11.7%, 13.0%, and 13.1%. No significant difference in age distribution for the levels of this antibody was observed in the control GECC group or the three high-risk groups. However, the positive rates of the three high-risk groups are more than twice those of the GECC group (11.7% approximately 13.1% vs 5.3%). This ratio coincides with the ratio of the probability of developing NPC in high-risk groups compared to that of the GECC group (also more than two times). The significance of this coincidence is discussed.

Prolonged infusion of quinolinic acid into rat striatum as an excitotoxic model of neurodegenerative disease

The neurotoxic effects of prolonged exposure of rat striatum to quinolinic acid in vivo was evaluated through assays of neurochemical markers for major neuronal populations. Continuous intrastriatal quinolinic acid infusion for 14 days produced a dose-dependent depletion of striatal choline acetyltransferase (ChAT) activity, glutamic acid decarboxylase (GAD) activity, and somatostatin content. ChAT activity was significantly reduced by quinolinic acid at doses of 90, 270, and 540 nmol/day, while GAD activity and somatostatin content were decreased only at doses of 270 and 540 nmol/day. NADPH-diaphorase histochemistry revealed a loss of striatal NADPH-diaphorase neurons as a result of quinolinic acid infusion at a dose of 270 nmol/day. The neurotoxic lesion induced by prolonged quinolinic acid exposure in vivo can be used as a potential model for studying excitotoxic mechanisms in neurodegenerative disease.

Differential appearance of T cell subsets in the large and small intestine of neonatal mice

We examined the appearance of intestinal intraepithelial lymphocytes (IEL) during the first 12 wk of life to gain insight into postnatal factors that contribute to the differences found between IEL in the large and small intestines of adult mice. Intestinal T cells were very infrequent at birth, but increased in number in the large and small intestine during the first 4 wk of life and then stabilized. The small intestinal epithelium at 2 wk of age contained mostly T cell receptor (TCR) alphabeta+, CD2+ T cells, unlike IEL in adult mice, which were composed of nearly equal proportions of CD2-, TCR alphabeta+ and TCR gammadelta+ cells. Between 2 and 3 wk of age, TCR gammadelta+, CD2- IEL increased greatly in the small intestine, whereas TCR alphabeta+ cells expressing CD2 decreased. By contrast, IEL in the large intestine at 2 and 3 wk of age were mostly TCR alphabeta+, CD2+ T cells similar to large intestinal IEL in adult mice. And finally, the expression of CD69 increased earlier and to higher levels on TCR alphabeta+ and TCR gammadelta+ IEL in the small intestine than in the large intestine. Our results demonstrate that IEL in the large and small intestine are phenotypically similar during suckling and that differences between these populations are established after weaning. Furthermore, the earlier accumulation of IEL with an activated adult IEL phenotype in the small intestine suggests that these T cells mature or expand in the gut and contribute to the maturation of immune function during postnatal life in mice.

Antibody to Epstein-Barr virus-specific DNase as a marker for the early detection of nasopharyngeal carcinoma

We have previously shown that high levels of antibody to Epstein-Barr virus (EBV)-specific DNase may be a useful marker for the early diagnosis of nasopharyngeal carcinoma (NPC). Sera from 3,368 males in an area with a high risk for the development of NPC were examined for the presence of antibody to EBV-specific DNase activity. Significant levels of the antibody were found in 430 of these sera. As a result, 32 individuals have attended the out-patient department of otolaryngology for clinical examination. Among them, one individual was found to have a stage II nasopharyngeal carcinoma. This result supports the value of determination of antibody to EBV-specific DNase as a marker for the early detection of NPC.

Endogenous excitatory amino acids tonically stimulate striatal acetylcholine release through NMDA but not AMPA receptors

The effect of stimulation and blockade of excitatory amino acid receptors on striatal acetylcholine release was examined using in vivo microdialysis in awake, freely moving rats. Local perfusion with the NMDA receptor antagonists CPP and MK-801 reduced striatal acetylcholine release, while NMDA itself enhanced striatal acetylcholine release. Co-perfusion with MK-801 blocked the NMDA-induced increase in acetylcholine release. The AMPA/kainate antagonists NBQX and GYKI 52466 alone did not decrease striatal acetylcholine release, although AMPA increased acetylcholine release. Co-perfusion with NBQX reduced the AMPA-induced elevation in acetylcholine release. These findings suggest that endogenous excitatory amino acids tonically stimulate striatal acetylcholine release through NMDA but not AMPA receptors.

N-methyl-D-aspartate receptor blockade differentially modifies regional cerebral metabolic responses to D1 and D2 dopamine agonists in rats with a unilateral 6-hydroxydopamine lesion

Dopamine and the excitatory amino acids play important roles in the control of motor behavior by the basal ganglia; elucidating the manner in which these transmitter systems interact may provide new therapeutic approaches to the treatment of movement disorders such as Parkinson's disease. The 2-deoxyglucose autoradiographic technique was used to examine the effect of N-methyl-D-aspartate receptor blockade on regional cerebral metabolic responses to D1 and D2 dopamine receptor stimulation in rats with a unilateral 6-hydroxydopamine lesion of the nigrostriatal pathway. The D1 agonist SKF 38393 (5 mg/kg, i.v.) increased glucose utilization markedly in entopeduncular nucleus and substantia nigra pars reticulata ipsilateral to the lesion, while the D2 agonist quinpirole (1 mg/kg, i.v.) had no effect in these striatal output regions. SKF 38393 and quinpirole reduced 2-deoxyglucose uptake to a similar extent in the lateral habenula, a region which receives afferent input from entopeduncular nucleus; quinpirole also decreased glucose utilization bilaterally in nucleus accumbens. Pretreatment with the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801 (0.1 mg/kg, i.v.), which had little effect on cerebral metabolism by itself, reduced the effect of SKF 38393 in entopeduncular nucleus and substantia nigra pars reticulata and prevented the effect of quinpirole in nucleus accumbens. MK-801 did not alter the SKF 38393-induced reduction in glucose utilization in lateral habenula, but did reduce the effect of quinpirole in this structure. When these drugs were administered in the same manner to a separate group of lesioned animals, MK-801 did not affect rotational behavior elicited by SKF 38393, but completely eliminated contralateral rotation and actually caused some ipsilateral rotation in response to quinpirole. These findings indicate that D1 and D2 receptor-associated brain mechanisms are differentially influenced by N-methyl-D-aspartate receptor stimulation. D2-mediated behavioral and cerebral metabolic responses appear to require concurrent N-methyl-D-aspartate receptor stimulation. On the other hand, the preservation of D1-mediated rotational behavior and reduced lateral habenula glucose metabolism in the presence of MK-801 despite attenuation of the effects of the D1 agonist in entopeduncular nucleus and substantia nigra pars reticulata suggests that D1 receptor-regulated neuronal pathways exhibit varying degrees of sensitivity to N-methyl-D-aspartate receptor blockade.

In vivo architecture of the manganese superoxide dismutase promoter

Mitochondrial manganese superoxide dismutase (Mn-SOD) is the primary cellular defense against damaging superoxide radicals generated by aerobic metabolism and as a consequence of inflammatory disease. Elevated expression of Mn-SOD therefore provides a potent cytoprotective advantage during acute inflammation. Mn-SOD contains a GC-rich and TATA/CAAT-less promoter characteristic of a housekeeping gene. In contrast, however, Mn-SOD expression is dramatically regulated in a variety of cells by numerous proinflammatory mediators, including lipopolysaccharide, tumor necrosis factor-alpha, and interleukin-1. To understand the underlying regulatory mechanisms controlling Mn-SOD expression, we utilized DNase I-hypersensitive (HS) site analysis, which revealed seven hypersensitive sites throughout the gene. Following high resolution DNase I HS site analysis, the promoter was found to contain five HS subsites, including a subsite that only appears following stimulus treatment. Dimethyl sulfate in vivo footprinting identified 10 putative constitutive protein-DNA binding sites in the proximal Mn-SOD promoter as well as two stimulus-specific enhanced guanine residues possibly due to alterations in chromatin structure. In vitro footprinting data implied that five of the binding sites may be occupied by a combination of Sp1 and gut-enriched Kr uppel-like factor. These studies have revealed the complex promoter architecture of a highly regulated cytoprotective gene.

Effect of winter cover crops on soil nitrogen availability, corn yield, and nitrate leaching

Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L.), annual ryegrass (Lolium multiflorum), and hairy vetch (Vicia villosa), and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L.) yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha(-1), referred to as N0, N1, N2, and N3, respectively) applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N 0, N 2, and N 3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency's drinking water standard of 10 mg N l(-1) even at recommended N rate for corn in this region (coastal Pacific Northwest). In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake) correlated well with average NO3-N during the high N leaching period for vetch cover crop treatment and for the control without the cover crops. The correlation, however, failed for other cover crops largely because of variable effectiveness of the cover crops in reducing NO3 leaching during the 5 years of this study. Further research is needed to determine if relay cover crops planted into standing summer crops is a more appropriate approach than fall seeding in this region to gain sufficient growth of the cover crop by fall. Testing with other main crops that have earlier harvest dates than corn is also needed to further validate the effectiveness of the bicultures to increase soil N availability while protecting the water quality.

Bisphosphonates inhibit expression of p63 by oral keratinocytes

Osteonecrosis of the jaw (ONJ), a side-effect of bisphosphonate therapy, is characterized by exposed bone that fails to heal within eight weeks. Healing time of oral epithelial wounds is decreased in the presence of amino-bisphosphonates; however, the mechanism remains unknown. We examined human tissue from individuals with ONJ and non-bisphosphonate-treated control individuals to identify changes in oral epithelium and connective tissue. Oral and intravenous bisphosphonate-treated ONJ sites had reduced numbers of basal epithelial progenitor cells, as demonstrated by a 13.8±1.1% and 31.9±5.8% reduction of p63 expression, respectively. No significant differences in proliferation rates, vessel density, or macrophage number were noted. In vitro treatment of clonal and primary oral keratinocytes with zoledronic acid (ZA) inhibited p63, and expression was rescued by the addition of mevalonate pathway intermediates. In addition, both ZA treatment and p63 shRNA knock-down impaired formation of 3D Ex Vivo Produced Oral Mucosa Equivalents (EVPOME) and closure of an in vitro scratch assay. Analysis of our data suggests that bisphosphonate treatment may delay oral epithelial healing by interfering with p63-positive progenitor cells in the basal layer of the oral epithelium in a mevalonate-pathway-dependent manner. This delay in healing may increase the likelihood of osteonecrosis developing in already-compromised bone.

Excitatory amino acid receptor antagonists modify regional cerebral metabolic responses to levodopa in 6-hydroxydopamine-lesioned rats

Excitatory amino acid receptor antagonists have been proposed as novel therapeutic agents to be used with levopoda in the treatment of Parkinson's disease. We examined the neural substrates for the interaction between levodopa and antagonists of either the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid or N-methyl-D-aspartate type of excitatory amino acid receptor using 2-deoxyglucose autoradiography. Thus, we compared the effects of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (10 mg/kg, i.v.) and the N-methyl-D-aspartate antagonist MK-801 (0.1 mg/kg, i.v.) on cerebral metabolic responses to levodopa (25 mg/kg, i.v., with 12.5 mg/kg benserazide) in rats with a unilateral nigrostriatal pathway lesion. Levodopa increased glucose utilization ipsilateral to the lesion in substantia nigra pars reticula (up to 104%), entopeduncular nucleus (up 90%) and subthalamic nucleus (up 30%), indicating that levodopa alters striatal output through the striatonigral, striatoentopeduncular and striatopallidal pathways. Levodopa also decreased metabolic rate in lateral habenula (down 39%), a target of projections from entopeduncular nucleus, implying a reduction in basal ganglia output. 2,3-Dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline and MK-801 by themselves did not affect glucose utilization in any of these regions. Pretreatment with 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline reduced the effect of levodopa in substantia nigra pars reticulata but not in entopeduncular nucleus or subthalamic nucleus, while MK-801 attenuated the effect of levodopa in all three of these structures; neither 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline nor MK-801 altered the effect of levodopa in lateral habenula. When given at the same doses to a separate group of lesioned animals, neither 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline nor MK-801 affected rotational behavior elicited by levodopa. These findings indicate that alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and N-methyl-D-aspartate receptor antagonists differentially modify dopamine receptor-mediated striatal output. alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor blockade may preferentially attenuate the effect of dopamine receptor activation on the striatonigral pathway, while N-methyl-D-aspartate blockade appears to reduce the actions of dopamine on the striatonigral, striatoentopeduncular and striatopallidal pathways.(ABSTRACT TRUNCATED AT 400 WORDS)

Porphyrin metabolisms in human skin commensal Propionibacterium acnes bacteria: potential application to monitor human radiation risk

Propionibacterium acnes (P. acnes), a Gram-positive anaerobic bacterium, is a commensal organism in human skin. Like human cells, the bacteria produce porphyrins, which exhibit fluorescence properties and make bacteria visible with a Wood's lamp. In this review, we compare the porphyrin biosynthesis in humans and P. acnes. Also, since P. acnes living on the surface of skin receive the same radiation exposure as humans, we envision that the changes in porphyrin profiles (the absorption spectra and/or metabolism) of P. acnes by radiation may mirror the response of human cells to radiation. The porphyrin profiles of P. acnes may be a more accurate reflection of radiation risk to the patient than other biodosimeters/biomarkers such as gene up-/down-regulation, which may be non-specific due to patient related factors such as autoimmune diseases. Lastly, we discuss the challenges and possible solutions for using the P. acnes response to predict the radiation risk.

Antimutagenic activity of extracts from Japanese eggplant

Using the Salmonella/microsome assay, the antimutagenic effects of specific components of the extracts from eggplant fruits were investigated. The eggplant fruit juice exhibited an antimutagenic activity against 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) induced mutagenicity. In some of the fractions extracted with several organic solvents (acetone, petroleum ether, ethyl acetate; and methanol), the activity was recognized. No mutagenicity or toxicity for Salmonella typhimurium TA98 in the presence of S9 mixture was observed with any of the extracts. It is suggested that there are multiple components of the activities that exist in the eggplant fruit. We isolated lutein from the 84% methanol (methanol/water, v/v) layer, pheophorbide or chlorophyllide from the 70% methanol layer and tannins containing sugar-moieties from the water layer. Pheophytin a and b, Mg-free derivatives of chlorophyll a and b, were isolated from the petroleum ether layer as possible antimutagens. The pheophytin a with S9 mix inhibited by 30-40% the mutagenicity of Trp-P-2.

Measuring the thickness of articular cartilage from MR images

We have developed an algorithm to estimate and display the spatial distribution of the thickness of articular cartilage in human knees. We used a simulation to derive the most appropriate formula for estimating thickness in digital images. The algorithm was tested by imaging a thickness phantom and comparing the results with the known dimensions of the phantom. The results demonstrated that the maximum error encountered in estimating thickness is one pixel while the average error is 0.4 pixels. We imaged a human knee on a cadaver in two separate sessions and used the two image sets to derive thickness maps of the patellar articular cartilage. The thickness maps generated independently from these image sets were very similar, indicating the reliability of the method in deriving accurate thickness estimates. J. Magn. Reson. Imaging 2001;13:120-126.