A simple microbiological assay for the stereospecific differentiation of alpha and beta isomers of arteether

A new rapid bioassay has been developed which can precisely differentiate between stereospecific alpha and beta isomers of the antimalarial drug arteether. This method was developed through the disc diffusion bioactivity tests wherein semisynthetically produced alpha arteether was able to inhibit the growth of E. coli strains which are defective in DNA gyrase enzyme. The wild type E. coli with intact DNA gyrase did not show this sensitivity to alpha arteether. The beta isomer of arteether was, however, ineffective against both the mutant and wild type strains. Direct experimental proof of gyrase involvement was obtained through mobilization of gyr genes by transformation of E. coli gyr- mutant strains with wild type gyrA clone pMK90 (carried on the thermo-inducible lambda Col E1 vector). This resulted in alpha arteether resistant and nalidixic acid sensitive phenotype clearly demonstrating the use of gyrA mutant strains in differentiating alpha and beta isomers of arteether by this simple bioassay.

The Src homology-2 domains (SH2 domains) of the protein tyrosine kinase p56lck: structure, mechanism and drug design

Src homology 2 (SH2) domains are found in many intercellular signal-transduction proteins which bind phosphotyrosine containing polypeptide sequences with high affinity and specificity and are considered potential targets for drug discovery. The protein p56lck is a member of the family of Src tyrosine kinase. The SH2 domain is thought to be responsible for the recruitment and regulation of p56lck kinase activity. There have been enormous efforts in the development of SH2 domain inhibitors for diseases such as cancer, osteoporosis and other diseases. This review focuses on current understanding of SH2 domain structure, mechanism and drug discovery with an emphasis on p56lck SH2 domain. A potential impact of the accumulated crystallographic effort on the development of methods for structure-based drug design is briefly addressed.

Effect of all-trans-retinoic acid on cytokine production in a murine macrophage cell line

All-trans-retinoic acid (RA) is a cancer chemopreventive agent and a pluripotent morphogen. It belongs to the class of retinoids that, besides being inducers of differentiation and growth-inhibitos, exert immunomodulatory and anti-inflammatory functions by mechanisms that are not clearly understood. Macrophages play different roles in diverse physiological processes, including ones in orchestrating immune and inflammatory responses. Products of activated macrophages such as interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNFalpha), interleukin-6, interleukin-8, and nitric oxide (NO) are important regulators of inflammatory reactions. In this study J774A. 1 cells, a murine macrophage cell line, was used to study the effects of RA on the production of NO, TNFalpha and IL-1beta. Cells were stimulated with lipopolysaccharide (LPS) with or without RA. RA depressed the levels of NO in a dose-dependent manner. NO production and subsequent nitrite accumulation in the media peaked at 24 h, plateaued at 48 h, and remained at the same level through 72 h. The presence of RA decreased TNFalpha levels, measured by both bioassay and enzyme-linked immunosorbent assay (ELISA), but these did not correlate with increased mRNA expression measured by reverse-transcriptase polymerase chain reaction at 6 h after LPS stimulation. IL-1beta protein production measured by both ELISA and bioassay decreased with RA treatment. IL-1beta mRNA expression was not affected by RA except at low doses. This study indicated that RA modulates cytokine production in J774A.1 macrophage cells. Inhibition of inflammatory cytokine production may play a role in the anti-inflammatory activity of RA. The results suggested that effects of RA are complex and are time and concentration dependent.

Disruption of sphingolipid metabolism in small intestines, liver and kidney of mice dosed subcutaneously with fumonisin B(1)

Fumonisin B(1) is a fungal inhibitor of ceramide synthase, a key enzyme in the de novo biosynthesis of sphingolipids. The resulting increase in tissue free sphinganine (and sometimes sphingosine) is used as a biomarker for fumonisin exposure. This study determined whether a single subcutaneous injection of fumonisin B(1) could cause an increase in free sphingoid bases in the intestinal epithelial cells of mice over 24 hr. It was hypothesized that fumonisin administered subcutaneously would be excreted into the small intestine via biliary excretion, and this should be detectable by increased sphingoid bases in the intestine. A significant time-dependent increase in sphingoid bases occurred in the intestine and liver peaking at 4-8 hr and declining to control levels by 24 hr. In the kidney the increase in free sphinganine was persistent. The parallel time course of the change in sphinganine in the intestine and liver suggested fumonisin B(1) was rapidly excreted into the small intestine. Rapid cell turnover in the intestine could account for the reversal of the sphinganine increase. The rapid return to the control level in liver was unexpected since ceramide synthase inhibition in cultured cells is persistent suggesting that liver handles fumonisin B(1) or sphingoid bases quite differently than kidney.

Effects of endotoxin and tumor necrosis factor alpha on regional brain neurotransmitters in mice

Alterations in regional brain concentration of dopamine (DA), norepinephrine (NE), serotonin (5-HT) and their metabolites were investigated in male BALB/c mice injected intraperitoneally with bacterial lipopolysaccharide (LPS, 2 mg kg(-1)) or recombinant murine tumor necrosis factor alpha (TNFalpha, 0.1 mg kg(-1)) at 2, 6, 12 and 24 h after the injection. At 2 h post-injection the LPS administration resulted in hypothermia, which was not apparent at later time points. No consistent effects were observed by either LPS or TNFalpha on peripheral leukocyte counts or plasma transaminase levels. Both LPS and TNFalpha slightly elevated NE metabolism in the striatum at 2-12 h. Concentrations of DA and its metabolites were significantly elevated only in the hypothalamus following TNFalpha at 24 h. Tumor necrosis factor alpha exerted pronounced effects on 5-HT metabolism in most brain regions at 2 h. Results suggest that the effect of LPS is more complex compared with TNFalpha because of the endogenous production of other cytokines including the TNFalpha.

Early fumonisin B1 toxicity in relation to disrupted sphingolipid metabolism in male BALB/c mice

Fumonisin B1 is a mycotoxin produced by Fusarium moniliforme, a common fungus in corn. It is known to cause a variety of diseases, including hepatic and renal degeneration in many species of laboratory and domestic animals. The known biochemical events in fumonisin B1 toxicity involve inhibition of ceramide synthase leading to disruption of sphingolipid metabolism. The effect of fumonisin B1 on ceramide and more complex sphingolipids in mice is not known. Groups of five male BALB/c mice each were injected with fumonisin B1 subcutaneously at doses of 0, 0.25, 0.75, 2.25, and 6.75 mg/kg body weight daily for 5 days. This protocol has been shown to produce a dose-dependent increase in apoptosis in liver and kidney of these animals. In the present study, liver, kidney, and brain were sampled and analyzed for free sphingoid bases and complex sphingolipids one day after the last treatment. A dose-related accumulation of free sphinganine and sphingosine was observed in liver and kidney, but not brain. The maximal increase in free sphinganine in kidney was 10-fold greater than in liver. Total phospholipids increased only in liver, whereas ceramide levels were not consistently altered in liver, kidney, or brain. In liver and kidney, fumonisin B1 treatment increased the sphinganine-containing complex sphingolipids, but no effect was observed on sphingosine-containing complex sphingolipids. No changes in complex sphingolipids were observed in brain. In liver, there was a close correlation between the extent of free sphinganine accumulation, and apoptosis and hepatopathy. This correlation was also evident in kidney but to a lessor extent. Nonetheless, the apoptosis and nephropathy occurred with little or no change in the levels of ceramide or more complex sphingolipids.

Increased production of proinflammatory cytokines by murine macrophages following oral exposure to sodium selenite but not to seleno-L-methionine

Selenium (Se) is an essential as well as a toxic trace element in animal and human nutrition. The immune system is a known target of Se intoxication. The objectives of the present study were to determine the effects of oral exposure to inorganic and organic forms of Se on the murine immune system and to compare the relative toxicity of the different chemical forms. Male BALB/c mice, 6-7 weeks of age, were exposed continuously to 0, 1, 3 or 9 ppm of Se as sodium selenite or seleno-L-methionine in the drinking water for 14 days. Following the treatment period mice were euthanized; trunk blood, spleen, thymus, liver and kidney were aseptically collected and organs weighed. Single-cell splenocyte cultures were made from the spleens and used to determine the effects of Se treatment on mitogen-induced lymphocyte blastogenesis and cytokine production. There were no changes in the 0 and 1 ppm Se groups as selenite. The thymus/body weight ratio was significantly reduced at 3 ppm Se as sodium selenite, and all other parameters remained unaffected. Exposure to 9 ppm of Se as sodium selenite resulted in marked decrease in body weight gain and relative organ weights. Treatment of mice with 9 ppm Se as sodium selenite increased erythrocyte counts in peripheral blood, reduced splenic cellularity, but increased the basal rate of splenocyte proliferation and induced a dose-dependent increase in phytohemagglutinin-P-induced lymphocyte proliferation. Sodium selenite at this dose increased the production of proinflammatory cytokines, tumor necrosis factor alpha and interleukin-1 beta, in lipopolysaccharide-stimulated splenic macrophages. Mice exposed to Se as seleno-L-methionine in the drinking water did not display any effects on the parameters examined at the dose range in this study. Results indicated that splenic macrophages and lymphocytes are sensitive to Se intoxication and there is a disparity in the immune system toxicity of inorganic and organic forms of Se administered via the drinking water, inorganic Se being more toxic.

Fumonisin hepatotoxicity is reduced in mice carrying the human tumour necrosis factor alpha transgene

Our previous studies have indicated that tumour necrosis factor alpha (TNFalpha) is involved in fumonisin B1 (FB1)-induced toxic responses. To investigate the role of TNFalpha in FB1 toxicity further we employed male transgenic mice expressing human TNFalpha gene (TG) and their wild-type equivalent C57BL/6 (WT). It was hypothesized that TG animals would have enhanced response to FB1. Repeated subcutaneous treatment of animals with 2.25 mg/kg per day of FB1 for 5 days caused minimal changes in body weight, organ weights, blood cell counts, and TNFalpha levels in plasma 1 day after the last injection. The mRNA for TNFalpha in liver increased in both TG and WT after FB1 treatment, providing evidence that FB1 induces hepatic TNFalpha expression. Liver and kidney lesions were found in TG after FB1 treatment; however, liver lesions seen in FB1-treated TG were considerably less than those observed in WT. The decreased hepatotoxicity in TG after FB1 treatment correlated with plasma concentrations of alanine aminotransferase and aspartate aminotransferase. Free sphinganine levels increased significantly in both the liver and kidney of WT and TG mice treated with FB1. The increase of free sphinganine in the liver from TG mice was 40% less than in WT mice and paralleled the changes in serum liver enzymes. Regional brain neurotransmitters and their metabolites were increased to a similar extent by FB1 in both WT and TG mice. Since the data did not support the original hypothesis, we investigated the levels of NFkappaB in liver. The cytosolic NFkappaB was significantly higher in TG compared with WT. Induction of NFkappaB, caused by increased endogenous production of TNFalpha, is a possible explanation of decreased FB1 hepatotoxicity in TG. The results suggest a protective role for NFkappaB in FB1-induced liver damage.

Increase in dopamine metabolites in murine striatum after oral exposure to inorganic but not organic form of selenium

Selenium (Se) is an essential as well as a toxic trace element. Se intoxication has been reported in both livestock and humans. The central nervous system is sensitive to Se poisoning; exposure to Se causes blind staggers in cattle, poliomyelomalacia in pigs, and nervous system disorders in humans. Differences in neurotoxicity between inorganic and organic Se have been demonstrated. In this study, groups of five male BALB/c mice each were administered sodium selenite or selenomethionine in drinking water ad libitum at 0, 1, 3, and 9 ppm as Se for 14 days. At the end of Se exposure, their brains were removed and dissected into different regions. The concentration of norepinephrine (NE), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT), and 5-hydroxyindolacetic acid (5-HIAA) were determined in each brain region. Food and water consumption and body weight gain were significantly decreased in the group treated with the highest concentration of sodium selenite. In mice administered sodium selenite at 3 and 9 ppm, DOPAC was significantly higher in the striatum than in the control group. The striatal HVA was also increased in the group treated with 3 ppm Se; the DA showed a similar pattern, but the increase was not statistically significant. No alterations of NE, 5-HT, or 5-HIAA levels were detected in any brain region of mice treated with sodium selenite. No significant differences in any parameter among the groups treated with selenomethionine were observed indicating that inorganic Se was more neurotoxic than organic Se via drinking water. The alterations of DA metabolites by inorganic Se in DA-rich striatum suggested a Se-specific increased neural activity of dopaminergic pathways. Results may be useful in further elucidation of neurotoxicity of Se and in establishing a safe level of intake for this element.

Effects of mountaineering training at high altitude (4,350 m) on physical work performance of women

BACKGROUND

Little is known about work performance of women in hypobaric hypoxia. Moreover, whether native women of moderate altitude (2,000-2,100 m) differ from their lowland counterparts in their ability to adjust to hypobaric hypoxia is also not known. Hence, physiological alterations on work performance due to mountaineering training with altitude adaptation was evaluated in two groups of women and compared to the differences in the responses of the native women of moderate altitudes (Highlanders-HL) with those of the plains (Lowlanders-LL).

METHODS

Pre-training tests were conducted at 2,100 m, then during sojourn to 4,350 m and re-tested again after return to 2,100 m. Physical work performance was assessed following standard step-test-exercise on a 30 cm stool with 24 cycles x min(-1) for 5 min. Heart rate, BP, ventilation, oxygen consumption and oxygen saturation were monitored at rest and during exercise followed by 5 min recovery in all three situations.

RESULTS

During initial assessment, HL showed higher cardiovascular efficiency with faster recovery of exercise heart rate. Both groups showed significant improvement in physical performance due to mountaineering training at high altitude (HA). The difference in performance between two groups narrowed down at 4,350 m and further reduced during re-test with maintenance of initial superiority of the HL.

CONCLUSIONS

a) Native women of moderate altitude (HL) are more fit compared with their plains counterparts (LL); b) All women achieved marked improvement in cardiovascular and respiratory efficiency as well as the step-test score due to intense mountaineering training at HA, and the rate of improvement in physical performance was higher in LL; c) Further, induction by trekking under progressive hypoxia coupled with rigorous mountaineering activity at HA merits in understanding better acclimatization and improved physical performance.

Lipid-protein interactions in the membrane: studies with model peptides

We have used fluorescence quenching of tryptophan-containing trans-membrane peptides by bromine-containing phospholipids to study the specificity of peptide-lipid interactions. We have synthesized peptides Ac-K2GLm WLnK2A-amide where m = 7 and n = 9 (L16) and m = 10 and n = 12 (L22). Binding constants of L22 for dioleoylphosphatidylserine [di(C18 : 1)PS] or dioleoylphosphatidic acid [di(C18 : 1)PA] relative to dieoleoylphosphatidylcholine [di(C18 : 1)PC] were close to 1. However, for L16, whilst the bulk of the di(C18 : 1)PA molecules bound with a binding constant relative to di(C18 : 1)PC close to 1, a small number of di(C18 : 1)PA molecules bound much more strongly. Assuming just one high affinity binding site on L16 for anionic lipid, the affinity of the site for di(C18 : 1)PS was calculated to be ca. 8 times that for di (C18 : 1)PC. The relative binding constant was little affected by ionic strength and close contact between the anionic headgroup of di(C18 : 1)PS and a lysine residue on the peptide was suggested. The relative binding constant for di(C18 : 1)PS at this high affinity site was less than for di(C18 : 1)PA. Cholesterol interacts with L22 with an affinity about 0.7 of that of di(C18 : 1)PC. The structure of the peptide itself is important. The peptide Ac-KKGYL6WL8YKKA-amide (Y2L14) incorporated into bilayers of dinervonylphosphatidylcholine [di(C24 : 1)PC] whereas L16 did not incorporate into this lipid. It is suggested that thinning of a lipid bilayer around a peptide to give optimal hydrophobic matching is less energetically unfavourable when a Tyr residue is located in the lipid/water interfacial region.

Fumonisin toxicity in a transgenic mouse model lacking the mdr1a/1b P-glycoprotein genes

The toxicity of fumonisin B(1) (FB(1)) was investigated in male mdr1a/1b double knockout (MDRK) mice, lacking the drug-transporting P-glycoproteins. These transgenic animals are deficient in their blood:brain barrier and accumulate different drugs in brain and other tissues. The MDRK and their wild-type counterparts, FVB mice, were injected subcutaneously with 2.25 mg/kg per day of FB(1) for 5 days and sampled one day after the last treatment in a protocol that has resulted in marked hepatic and renal damage in other strains. FB(1) caused liver enlargement in both FVB and MDRK. Hematological parameters were not affected in either strain. Plasma levels of alanine aminotransferase and aspartate aminotransferase, measures of liver damage, were increased by FB(1) in both FVB and MDRK mice. Histopathological evaluation of liver corroborated this finding. Kidney lesions were induced by FB(1) in both types of mice. Concentrations of free sphingosine and sphinganine increased in liver and kidney of both strains after the FB(1) treatment, although the increase in liver sphingoid bases was half as much in MDRK as compared to FVB. The levels of sphinganine-containing complex sphingolipids were increased in kidney. The levels of sphingosine-containing complex sphingolipids in kidney were unaffected by FB(1) treatment but were significantly lower in control MDRK than in FVB mice. The levels of neurotransmitters and their metabolites were similarly affected in both strains by FB(1), suggesting no influence of disrupted blood:brain barrier on FB(1)-induced neurotoxicity. In both strains, the liver mRNA for tumor necrosis factor alpha was increased; however, the increase was statistically significant only in FVB. It was apparent that mice deficient in P-glycoprotein do not exhibit greater sensitivity to FB(1), the cellular or brain transport of FB(1) appears to be independent of this multidrug transporting system.

Effects of aromatic residues at the ends of transmembrane alpha-helices on helix interactions with lipid bilayers

We have studied the effects of aromatic residues at the ends of peptides of the type Ac-KKGL(n)()WL(m)()KKA-amide on their interactions with lipid bilayers as a function of lipid fatty acyl chain length, physical phase, and charge. Peptide Ac-KKGFL(6)WL(8)FKKA-amide (F(2)L(14)) incorporated into bilayers of phosphatidylcholines containing monounsaturated fatty acyl chains of lengths C14-C24 at a peptide:lipid molar ratio of 1:100 in contrast to Ac-KKGL(7)WL(9)KKA-amide (L(16)) which did not incorporate at all into dierucoylphosphatidylcholine [di(C24:1)PC]; Ac-KKGYL(6)WL(8)YKKA-amide (Y(2)L(14)) incorporated partly into di(C24:1)PC. Lipid-binding constants relative to that for dioleoylphosphatidylcholine (C18:1)PC were obtained using a fluorescence quenching method. For Y(2)L(14) and F(2)L(14), relative lipid-binding constants increased with increasing fatty acyl chain length from C14 to C24; strongest binding did not occur at the point where the hydrophobic length of the peptide equalled the hydrophobic thickness of the bilayer. For Ac-KKGYL(9)WL(11)YKKA-amide (Y(2)L(20)), increasing chain length from C18 to C24 had little effect on relative binding constants. Anionic phospholipids bound more strongly than zwitterionic phospholipids to Y(2)L(14) and Y(2)L(20) but effects of charge were relatively small. In two phase (gel and liquid crystalline) mixtures, all the peptides partitioned more strongly into liquid crystalline than gel phase; effects were independent of the structure of the peptide or of the lipid (dipalmitoylphosphatidylcholine or bovine brain sphingomyelin). Addition of cholesterol had little effect on incorporation of the peptides into lipid bilayers. It is concluded that the presence of aromatic residues at the ends of transmembrane alpha-helices effectively buffers them against changes in bilayer thickness caused either by an increase in the chain length of the phospholipid or by the presence of cholesterol.

Tolerance to fumonisin toxicity in a mouse strain lacking the P75 tumor necrosis factor receptor

Fumonisin B1 (FB1), a potent mycotoxin prevalent in corn and cereals, causes a variety of toxic effects in different mammalian species. The biochemical responses of FB1 involve inhibition of ceramide synthase leading to accumulation of free sphingoid bases and a possible involvement of tumor necrosis factor alpha (TNFalpha). To further characterize the role of TNFalpha, toxic response to FB1 was investigated in male C57BL/6J mice (WT) and a corresponding TNFalpha receptor knockout (TRK) strain, genetically modified to lack the TNFalpha1b receptor. The hepatotoxic effects of 5 daily injections of 2.25 mg/kg per day of FB1 were observed in WT but were reduced in TRK, evidenced by circulating alanine aminotransferase and aspartate aminotransferase levels and histopathological evaluation of the tissue. FB1 induced TNFalpha expression in the livers of both WT and TRK mice to a similar extent (3-4 fold over control); however, a corresponding increase of cellular NFkappaB, expected after the downstream cellular signaling of TNFalpha, was noted only in the WT. Accumulation of liver sphingosine after FB1 treatment was similar in both WT and TRK, but the FB1-induced increases in liver sphinganine and kidney sphingosine and sphinganine were lower in TRK than in WT. Results emphasized the role of TNFalpha in FB1-induced hepatotoxicity in mice and the possible relationship of sphingoid base accumulation and TNFalpha induction. Moreover, the presence of TNFalpha receptor 1b appears to be important in mediating the hepatotoxic responses of TNFalpha and FB1 in mice.

Altered dopamine turnover in murine hypothalamus after low-dose continuous oral administration of aluminum

Aluminum, a known neurotoxic substance, has been suggested as a possible contributing factor in the pathogenesis of Alzheimer's disease. Ground-water pollution by aluminum has been recently reported. In the current study groups of 5 male BALB/c mice were administered aluminum ammonium sulfate in drinking water ad libitum at 0, 5, 25, and 125 mg/L aluminum for 4 weeks. At the termination of aluminum exposure, their brains were removed and dissected into cerebrum, cerebellum, medulla oblongata, midbrain, corpus striatum, and hypothalamus. The concentration of norepinephrine (NE), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA), were determined in each brain area. DA, DOPAC, and HVA levels were lower in the hypothalamus of aluminum-treated mice, most notably in the low-dose group, as compared with control. No marked alterations in NE, 5-HT, and 5-HIAA levels were detected in any brain region. Changes in the concentration of DA and its metabolites measured in the hypothalamus suggest an inhibition of DA synthesis by aluminum.

Increased responsiveness to intravenous lipopolysaccharide challenge in steers grazing endophyte-infected tall fescue compared with steers grazing endophyte-free tall fescue

Fescue toxicosis in cattle occurs as a result of consumption of ergot alkaloids in endophyte-infected (E+, Neotyphodium coenophialum) tall fescue (Festuca arundinacea). The condition is characterized by pyrexia, decreased weight gains, rough hair coats, and decreased calving rates. The objective of this experiment was to investigate whether steers grazing E+ fescue have altered host response to lipopolysaccharide (endotoxin, LPS) challenge compared with steers grazing endophyte-free (E-) fescue. Angus steers (n=8) had continuously grazed either E+ (n=4) or E- (n=4) tall fescue grass for 8 months prior to the experiment. The E+ steers had lower body weight, depressed average daily gain, and decreased basal serum prolactin compared with the E- steers prior to LPS administration. Each steer received a single bolus i.v. injection of LPS (0.2 microgram/kg body weight; Escherichia coli; 026:B6) dissolved in sterile saline, and blood was serially collected every 30 min for 4 h and at 24 h post LPS administration. LPS increased serum tumor necrosis factor-alpha (TNF-alpha), cortisol, and haptoglobin but decreased plasma glucose and IGF-I. Importantly, however, TNF-alpha, cortisol, and IGF-I responses to LPS were greater in E+ compared with E- steers. These results indicated that animals grazing E+ fescue had altered integrated metabolic host response compared with animals grazing E- fescue. Potentially, combined exposure to E+ fescue and a bacterial LPS could have greater deleterious effects on the animal compared with exposure to only one of the two and would likely lead to increased catabolism.

Modulation of tumor necrosis factor alpha expression in mouse brain after exposure to aluminum in drinking water

Aluminum, a known neurotoxic substance and a ground-water pollutant, is a possible contributing factor in various nervous disorders including Alzheimer's disease. It has been hypothesized that cytokines are involved in aluminum neurotoxicity. We investigated the alterations in mRNA expression of tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), and interferon gamma (IFNgamma), cytokines related to neuronal damage, in cerebrum and peripheral immune cells of mice after exposure to aluminum through drinking water. Groups of male BALB/c mice were administered aluminum ammonium sulfate in drinking water ad libitum at 0, 5, 25, and 125 ppm aluminum for 1 month. An additional group received 250 ppm ammonium as ammonium sulfate. After treatment, the cerebrum, splenic macrophages and lymphocytes were collected. The expression of TNFalpha mRNA in cerebrum was significantly increased among aluminum-treated groups compared with the control, in a dose-dependent manner. Other cytokines did not show any aluminum-related effects. In peripheral cells, there were no significant differences of cytokine mRNA expressions among treatment groups. Increased expression of TNFalpha mRNA by aluminum in cerebrum may reflect activation of microglia, a major source of TNFalpha in this brain region. Because the aluminum-induced alteration in cytokine message occurred at aluminum concentrations similar to those noted in contaminated water, these results may be relevant in considering the risk of aluminum neurotoxicity in drinking water.

Increased proinflammatory cytokines production by ergotamine in male BALB/c mice

The ergopeptine alkaloid ergotamine (ET) mimics the effects of ergopeptine alkaloids found in endophyte-infected (E+) fescue forage considered causative for fescue toxicosis. Altered immune capacity, compromised intake and thermoregulation, and inflammatory changes are observed in fescue toxicosis. Taken together, these suggest the cytokine pattern may be altered by ergot alkaloids. Thus, the objective of this study was to determine whether major splenocyte-derived cytokines--interleukin 2 (IL-2), interleukin 4 (IL-4), interferon gamma (IFN-gamma)--and macrophage-derived cytokines--interleukin 1beta, (IL-1beta), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha)--were affected by ergotamine. Two sets of male BALB/c mice (n = 5/treatment) were treated with ergotamine tartrate (s.c.) for 10 d at doses of 0 (control), 0.4, 2, 10, or 50 mg/kg body weight. Twenty-four hours after the last treatment, splenocytes (S) were isolated from one set of animals and macrophages (Mphi) from the other set for determination of IL-2, IL-4, INF-gamma, and IL-1beta, IL-6, TNF-alpha, respectively. Following activation with 5 microg/ml concanavalin A (Con A) (S) and 10 microg/ml lipopolysaccharide (LPS) (Mphi), cells were incubated for 48 and 24 h, respectively, and supernatants were collected and assayed for respective cytokines by enzyme-linked immunosorbent assay (ELISA). Additionally, differential white blood cell (WBC) counts were performed and the neutrophil (N):lymphocyte (L) ratio calculated. Ergotamine treatment significantly increased IL-6 levels at the 2.0 mg/kg dose and greater and TNF-alpha at the highest dose. There was no treatment effect on IL-1beta, IL-2, IL-4, and IFN-gamma. Also, no effect was observed upon total and differential WBC counts as well as N:L ratio. Ergotamine affected the proinflammatory cytokine IL-6, and this increase may contribute to fescue tosicosis.

Analysis of taxol and major taxoids in Himalayan yew, Taxus wallichiana

A reversed-phase column liquid chromatography method for the analysis of taxol, 10-deacetylbaccatin III, baccatin IV, 1-hydroxybaccatin I, 2-acetoxybrevifoliol, brevifoliol, 2'-deacetoxydecinnamoyltaxinine J and 2'-deacetoxytaxinine J in yew needles has been developed using a Nova-Pak Phenyl column and a binary gradient profile. The various aspects of analysis such as extraction efficiency, detection limits, reproducibility and peak purity were validated using UV-Vis as well as photodiode array detection.

Amino acid substitution in alpha-helix 7 of Cry1Ac delta-endotoxin of Bacillus thuringiensis leads to enhanced toxicity to Helicoverpa armigera Hubner

Insecticidal proteins or delta-endotoxins of Bacillus thuringiensis are highly toxic to a wide range of agronomically important pests. The toxins are formed of three structural domains. The N-terminal domain is a bundle of eight alpha-helices and is implicated in pore formation in insect midgut epithelial membranes. All the delta-endotoxins share a common hydrophobic motif of eight amino acids in alpha-helix 7. A similar motif is also present in fragment B of diphtheria toxin (DT). Site-directed mutagenesis of Cry1Ac delta-endotoxin of B. thuringiensis was carried out to substitute its hydrophobic motif with that of DT fragment B. The mutant toxin was shown to be more toxic to the larvae of Helicoverpa armigera (cotton bollworm) than the wild-type toxin. Voltage clamp analysis with planar lipid bilayers revealed that the mutant toxin opens larger ion channels and induces higher levels of conductance than the wild-type toxin.

The prolactin response to fenfluramine in schizophrenia is associated with negative symptoms

We examined the serotonergic system in drug-free inpatients [schizophrenia (n=28) and schizoaffective (n=7)] by administering a challenge dose of oral dl-fenfluramine (fenfluramine) in a controlled angiocatheter study. Seventeen of these patients were also randomized to a placebo condition in addition to receiving fenfluramine. Response to fenfluramine as reflected by changes in serum prolactin and cortisol were examined by repeated measures ANOVA, as well as Area Under the Curves (AUCs). The prolactin response, but not the cortisol response, was significantly correlated with measures of negative symptoms.

Hallucinations in the acute schizophrenic-type psychosis: effects of gender and age of illness onset

Our objective was to test the hypothesis that gender, the age of illness onset, or the interaction between these two variables, would distinguish acutely ill schizophrenic and schizoaffective patients who hallucinated from those who did not. Hallucinatory experiences were measured by the hallucination item of the Brief Psychiatric Rating Scale in a sample of 160 drug-free inpatients admitted for the treatment of an acute episode. Patients were categorized as either non-hallucinators or hallucinators. An additional analysis included only those who had 'severe' hallucinations (i.e., score > or = 5). Female gender, but not age of onset, predicted a higher frequency of hallucinations (irrespective of degree of severity) in the total sample, but specifically in the schizophrenic patients. These results indicate that there may be gender differences in the propensity to experience hallucinations during the acute schizophrenic episode.

Serine palmitoyltransferase inhibition reverses anti-proliferative effects of ceramide synthase inhibition in cultured renal cells and suppresses free sphingoid base accumulation in kidney of BALBc mice

The purpose of this study was to determine the ability of the fungal serine palmitoyltransferase (SPT) inhibitor, myriocin, to prevent the anti-proliferative and cytotoxic effects of fumonisin B(1) in cultured pig kidney epithelial cells, LLC-PK(1). In an earlier study with LLC-PK(1) cells, β-chloroalanine (a nonspecific SPT inhibitor) was found to inhibit the fumonisin-induced accumulation of free sphinganine by >90% but only partially reversed (50-60%) fumonisin's antiproliferative and cytotoxic effects. β-Chloroalanine is not the ideal SPT inhibitor for this type of study because it also inhibits other pyridoxal 5'-phosphate-dependent enzymes. A potent and selective fungal SPT inhibitor (myriocin) was partially purified from liquid cultures of Isaria (=Cordyceps) sinclairii by a combination of organic extraction and column chromatography. The various fractions were bioassayed for their ability to inhibit fumonisin-induced sphinganine accumulation in LLC-PK(1) cells. The activity in partially purified material was compared to the activity of highly purified myriocin and the results expressed as myriocin equivalents. The estimated IC(50) and IC(95) for inhibition of fumonisin-induced sphinganine accumulation were approximately 1.8 and 22 nM, respectively. The IC(95) concentration of the fungal SPT inhibitor reversed the antiproliferative effects and prevented fumonisin-induced apoptosis after 48 h exposure to 50 μM fumonisin B(1). The SPT inhibitor was also effective at reducing free sphinganine in vivo. Free sphinganine concentration was reduced 60% in kidney of mice injected i.p. with SPT inhibitor plus fumonisin B(1) when compared to fumonisin B(1) alone. The ability of SPT inhibition to reduce fumonisin B(1)-induced sphinganine accumulation in vivo may be useful in the development of therapeutic agents for treatment of animals suspected to have been exposed to toxic levels of fumonisin in feeds.

Effect of vitamin C and E in modulating peripheral vascular response to local cold stimulus in man at high altitude

At high altitude (HA), cold stress is aggravated by hypoxia, perhaps due to the increased formation of free radicals which trigger oxidative stress. This may be one of the contributing factors for adverse effects including disturbances in microcirculation and capillary permeability resulting in decreased peripheral blood flow. This leads to altered cold-induced-vasodilatation (CIVD) response on exposure to HA. The present study was conducted on 40 male volunteers (4 groups of 10 each) to evaluate the utility of supplementation of vitamin C (500 mg/d)and vitamin E (400 mg/d) singly, as well as in combination, in modulating peripheral vascular response by assessing CIVD response under local cold stimulus both at Delhi (200 m) and at HA (3,700 m). On exposure to 3,700 m, decreased CIVD response was observed in all the groups. The responses were better in vitamin supplemented groups, in general, as compared to the placebo group. The best CIVD response was seen in the vitamin C (singly)-treated group. Administration of vitamin C and E together did not result in any additional benefit. Facilitation of CIVD response due to supplementation of vitamin C may be attributed to its (a) antioxidant effect, and (b) major physiological functions of increased metabolism and thermogenic properties, facilitation of collagen synthesis, restoration of intercellular substances and better maintenance of the rheological status of the blood. Hence, vitamin C is effective for improving peripheral blood flow and thereby reduces the incidence of cold injuries during acclimatization or outdoor duties at HA.

Biological activity of the labdane diterpenes

Biological activity of diterpenes of the labdane skeleton, isolated from the terrestrial plants and marine sources during the last ten years has been reviewed.

Region-specific decrease of dopamine and its metabolites in brains of mice given ergotamine

Ergot alkaloids (EA) such as the ergopeptine alkaloid ergotamine (ET) are adrenergic, dopaminergic, and serotonergic agents. The objective of this experiment was to investigate regional brain neurotransmitter alterations caused by EA. Male BALB/c mice were treated s.c. daily with ergotamine tartrate for 10 d at 0 (saline), 0.4, 2, 10, or 50 mg/kg body weight. Twenty-four hours after the last treatment, animals were sacrificed and brains dissected. Regional concentrations of norepinephrine (NE), dopamine (DA), serotonin (5-HT), and metabolites 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindole-3-acetic acid (5-HIAA) were measured by high-performance liquid chromatography (HPLC). Moreover, selected organ weights and plasma prolactin (PRL) were determined. Dopamine concentration was significantly reduced by ET at all doses in the striatal and hypothalamic regions. A reduction of the DA metabolite HVA occurred in striatum at only the highest dose, whereas in the hypothalamus both HVA and DOPAC were markedly reduced. Concentrations of NE, MHPG, 5-HT, and 5-HIAA were not affected by treatment in these regions. In the cerebellum, MHPG was significantly elevated at the 50 mg/kg dose. No effect of treatment was observed in the cerebrum, medulla, and midbrain. Further, no treatment-related differences in plasma PRL and organ weights other than a significant liver weight decrease at intermediate doses were found. Therefore, the effects of ET were predominantly upon DA metabolism in the corpus striatum and hypothalamus. The reductions in DA, HVA, and DOPAC indicate decreased DA synthesis.

A brevifoliol analogue from the Himalyan yew Taxus wallichiana

The needles of Taxus wallichiana gave a new brevifoliol derivative whose structure was established by spectral data.

A decrease of reelin expression as a putative vulnerability factor in schizophrenia

Postmortem prefrontal cortices (PFC) (Brodmann's areas 10 and 46), temporal cortices (Brodmann's area 22), hippocampi, caudate nuclei, and cerebella of schizophrenia patients and their matched nonpsychiatric subjects were compared for reelin (RELN) mRNA and reelin (RELN) protein content. In all of the brain areas studied, RELN and its mRNA were significantly reduced (approximately 50%) in patients with schizophrenia; this decrease was similar in patients affected by undifferentiated or paranoid schizophrenia. To exclude possible artifacts caused by postmortem mRNA degradation, we measured the mRNAs in the same PFC extracts from gamma-aminobutyric acid (GABA)A receptors alpha1 and alpha5 and nicotinic acetylcholine receptor alpha7 subunits. Whereas the expression of the alpha7 nicotinic acetylcholine receptor subunit was normal, that of the alpha1 and alpha5 receptor subunits of GABAA was increased when schizophrenia was present. RELN mRNA was preferentially expressed in GABAergic interneurons of PFC, temporal cortex, hippocampus, and glutamatergic granule cells of cerebellum. A protein putatively functioning as an intracellular target for the signal-transduction cascade triggered by RELN protein released into the extracellular matrix is termed mouse disabled-1 (DAB1) and is expressed at comparable levels in the neuroplasm of the PFC and hippocampal pyramidal neurons, cerebellar Purkinje neurons of schizophrenia patients, and nonpsychiatric subjects; these three types of neurons do not express RELN protein. In the same samples of temporal cortex, we found a decrease in RELN protein of approximately 50% but no changes in DAB1 protein expression. We also observed a large (up to 70%) decrease of GAD67 but only a small decrease of GAD65 protein content. These findings are interpreted within a neurodevelopmental/vulnerability "two-hit" model for the etiology of schizophrenia.

Fumonisin B1-induced increases in neurotransmitter metabolite levels in different brain regions of BALB/c mice

Fumonisin B1, a toxin produced by Fusarium moniliforme, causes a variety of diseases in animals, including those involving the central nervous system, such as equine leukoencephalomalacia (ELEM). The changes of biogenic amines may reflect fumonisin B1 neurotoxicity. It was previously reported that consumption of feed contaminated with Fusarium moniliforme cultures produced an elevation of 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of 5-hydroxytryptamine (5-HT), in whole rat brains. In a subsequent study from the same laboratory, rats given fumonisin B1 orally for 4 weeks showed no changes in neurotransmitter levels of the whole brain. In the current study, groups of five male BALB/c mice were injected with fumonisin B1 subcutaneously at doses of 0, 0.25, 0.75, 2.25, 6.75 mg kg-1 body weight daily for 5 days. One day after the last treatment, their brains were dissected into cerebrum, cerebellum, medulla oblongata, midbrain, corpus striatum and hypothalamus. Levels of norepinephrine (NE), dopamine (DA), DA metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and 5-HT and 5-HIAA were determined. A significant elevation of HVA was observed in mice treated with high doses of fumonisin B1 in most brain regions. In striatum, a decrease of 5-HT was observed by the fumonisin B1 treatment. Ratios of neurotransmitters to metabolites such as HVA/DA and 5-HIAA/5-HT were elevated in several brain regions of the treated groups. An accumulation of neurotransmitter metabolites is suggestive of increased neuronal activity or interference with their efflux from cells.

Pretreatment plasma homovanillic acid in schizophrenia and schizoaffective disorder: the influence of demographic variables and the inpatient drug-free period

BACKGROUND

The relationship between plasma homovanillic acid (pHVA) and schizophrenic symptoms has not been conclusively determined. We reexamine pHVA levels in a new sample of patients with emphasis on demographic variables and the drug-free period.

METHODS

Plasma HVA levels were studied in 54 schizophrenic and schizoaffective-disordered, drug-free inpatients suffering from a psychotic exacerbation.

RESULTS

A significant correlation was observed between pHVA levels and the number of inpatient drug-free days in the total sample, as well as the schizophrenic patient subsample. Further, pHVA was significantly and positively correlated with the duration of illness in the schizophrenic patient subsample. Plasma HVA correlations with behavior, as measured by Brief Psychiatric Rating Scale factors (anxiety/depression and hostility/suspiciousness), emerged only when considering schizophrenic patients drug-free for more than 2 weeks. No correlation was found between pHVA and the age of illness onset or the duration of the delay of treatment of the first psychotic episode.

CONCLUSIONS

The effects of antipsychotic withdrawal on levels of pHVA in clinical populations may have to be examined and controlled for in future studies attempting to study the relationship between this metabolite and behavior in acutely ill, drug-free schizophrenic patients.

Verapamil for the treatment of acute mania: a double-blind, placebo-controlled trial

OBJECTIVE

This study investigated the efficacy of verapamil in acute mania.

METHOD

The study was a 3-week double-blind, random-assignment, parallel-group, placebo-controlled inpatient trial of verapamil for patients with acute mania. Of the 32 study patients, 15 were given placebo and 17 were given verapamil.

RESULTS

Mean absolute change scores on the Mania Rating Scale at endpoint, with baseline scores as the covariates, did not differ between the verapamil and placebo groups. There were no significant differences between the two groups in age, sex, and presence of psychosis.

CONCLUSIONS

The investigators found no benefit of verapamil over placebo in treating acute mania.

Tumor necrosis factor-alpha as a contributor in fumonisin B1 toxicity

Fumonisin B1 is a toxic product of Fusarium moniliforme, which inhibits ceramide synthase, leading to accumulation of free sphingoid bases. Despite its known biochemical action, the mechanism of toxicity is not fully understood. Male BALB/c mice were injected subcutaneously with 0 to 6.75 mg/kg/day of fumonisin B1 for 5 days. One day after the last treatment, spleens were collected, and peritoneal macrophages were obtained from separate groups after an intraperitoneal injection of thioglycolate broth. Peripheral leukocyte counts were increased and kidney weights were decreased by fumonisin B1 treatment. Presence of apoptotic cells in the liver and kidney of treated mice was confirmed by enzymatic immunoassay. Macrophages cultured with lipopolysaccharide indicated an increased secretion of tumor necrosis factor-alpha (TNF-alpha) but not of interleukin-1alpha. No effect was seen on interferon-gamma production when splenocytes were incubated with concanavalin A. Elevation of leukocyte and reticulocyte counts was abrogated by pretreatment with anti-TNF-alpha antibody before a single dose of fumonisin B1 (25 mg/kg), supporting the hypothesis that the fumonisin B1 toxicity involves TNF-alpha. Cultures of J774A.1 cells, when treated with fumonisin B1, produced TNF-alpha in vitro. Results indicate that fumonisin B1 toxicity may involve secretion of TNF-alpha by TNF-alpha-producing cells without altering interleukin-1alpha or interferon-gamma. The influence on TNF-alpha-production may be a contributing factor to fumonisin B1-induced apoptosis and other observed toxic effects in animals.

The effect of FMRF-amide-like peptides on electrical activity in isolated mammalian spinal cord

FMRFamide and seven FMRFamide-like peptides were manually synthesized on solid phase and their effects tested upon the amplitude of the dorsal root-ventral root monosynaptic reflex (MSR) and dorsal horn field potentials (FP) in an isolated preparation of rat spinal cord. FLFQPQRFamide (NPFF) and AGEGLSSPFWSLAAPQRFamide (NPAF) both depressed a fast component of the FP with similar potencies. FMRFamide also inhibited the FP but its potency was much lower. NPFF and NPAF potentiated the amplitude of the MSR while FMRFamide had no effect. PQRFamide, PFRFamide, FFRFamide, DPQRFamide and Fmoc-FLFQPQRFamide were also examined on the MSR. PQRFamide and PFRFamide potentiated the MSR whereas FFRFamide and DPQRFamide caused a small depression at high concentrations. The increase in amplitude of the MSR induced by NPFF was completely abolished when the N-terminal was left protected with an Fmoc-group. The results suggest that PFRFamide and PQRFamide may act as agonists of NPFF and NPAF whereas the other peptides did not show such activity.

Plant regeneration via somatic embryogenesis in pigeonpea (Cajanus cajan L. Millsp)

Efficient plant regeneration via somatic embryogenesis has been developed in pigeonpea. Cotyledon and leaf explants from 10-day-old seedlings produced embryogenic callus and somatic embryos when cultured on Murashige and Skoog (MS) medium supplemented with 10 µM thidiazuron (TDZ). Subsequent withdrawal of TDZ from the induction medium resulted in the maturation and growth of the embryos into plantlets on MS basal medium. The rooted plantlets were transferred and acclimatized on vermiculite where they showed normal morphological characters.

Hydrophobic mismatch and the incorporation of peptides into lipid bilayers: a possible mechanism for retention in the Golgi

Preferential interaction of trans-membrane alpha-helices whose hydrophobic length matches the hydrophobic thickness of the lipid bilayer could be a mechanism of retention in the Golgi apparatus. We have used fluorescence methods to study the interaction of peptides Ac-K2-G-Lm-W-Ln-K2-A-amide (Pm+n) with bilayers of phosphatidylcholines with chain lengths between C14 and C24. The peptide P22 (m = 10, n = 12) incorporates into all bilayers, but P16 (m = 7, n = 9) does not incorporate into bilayers when the fatty acyl chain length is C24 and only partly incorporates into bilayers where the chain length is C22. The strongest binding is seen when the hydrophobic length of the peptide matches the calculated hydrophobic thickness of the bilayer. It is suggested that a too-thin bilayer can match to a too-long peptide both by stretching of the lipid and by tilting of the peptide. However, a too-thick bilayer can only match a too-thin peptide by compression of the lipid, which becomes energetically unfavorable when the difference between the bilayer thickness and the peptide length exceeds about 10 A. The presence of cholesterol in the bilayer leads to a marked reduction in the incorporation of P16 into bilayers where the chain length is C18. Hydrophobic mismatch could explain retention of proteins with short trans-membrane alpha-helical domains in the Golgi, the effect following largely from the low concentration of cholesterol in the Golgi membrane compared to that in the plasma membrane.

Demonstration of in-situ apoptosis in mouse liver and kidney after short-term repeated exposure to fumonisin B1

Fumonisin B1, a mycotoxin produced by Fusarium moniliforme, inhibits the activity of ceramide synthetase, the key enzyme in sphingolipid biosynthesis, leading to accumulation ofsphinganine and sphingosine. Ceramide and other sphingolipid pathways have been implicated in signal-induced apoptosis in cells. Groups of male BALB/c mice received subcutaneous injections (0, 0.25, 0.75, 2.25 or 6.25 mg/kg) of fumonisin B1 daily for 5 days and the liver and kidneys were sampled 1 day after the last injection. A decrease in kidney weight was observed after fumonisin treatment. A "blind" random evaluation of stained sections revealed dose-dependent fumonisin B1-associated hepatic and renal lesions in all groups. Terminal uridine triphosphate (UTP) nick-end labelling (TUNEL) in liver and kidney sections confirmed the presence of dose-related apoptotic cells at all treatment levels. Thus fumonisin B1 produced apoptosis after a brief exposure to relatively low doses. The toxicity of fumonisin B1 was greater than that previously found in studies on oral toxicity.

Outcome of 350 implanted chest ports placed by interventional radiologists

PURPOSE

To determine the outcome of implanted chest ports placed by interventional radiologists.

MATERIALS AND METHODS

Between June 1993 and July 1996, a single institution placed 350 implanted chest ports in 346 patients by means of the subclavian vein approach. The medical records of these patients were reviewed to determine the outcome of the ports. Ports were implanted for chemotherapy (n = 341), blood transfusion (n = 7), or antibiotics (n = 2).

RESULTS

Immediate complications were seven (2%) pneumothoraces and one (0.3%) hematoma. Four (1.1%) of the pneumothoraces necessitated hospital admission and treatment with a chest tube. The remaining three were managed on an outpatient basis. One was successfully treated in the interventional suite by catheter suction. Two pneumothoraces were observed and resolved spontaneously. Mean time of patient follow-up was 260 days (range, 22-929 days). Total time of follow-up was 91,000 catheter days. Delayed complications were 10 cases of thrombosis (2.9% or 0.11 per 1,000 catheter days) of the subclavian vein, four infections (1.1% or 0.04 per 1,000 catheter days), four catheter coiling or tip malpositions (1.1% or 0.04 per 1,000 catheter days), three catheter occlusions (0.9% or 0.03 per 1,000 catheter days), and one catheter leak (0.3% or 0.01 per 1,000 catheter days). Six (1.7%) ports had to be removed as a result of a delayed complication.

CONCLUSION

Chest port implantation by interventional radiologists within the radiology department is a successful and safe procedure with complication rates equivalent to, or lower than, those reported in surgical placement series.

CSF neurotensin concentrations and antipsychotic treatment in schizophrenia and schizoaffective disorder

OBJECTIVE

The relationship between CSF neurotensin concentrations and measures of psychopathology in patients with schizophrenia or schizoaffective disorder was examined before and after treatment with antipsychotic drugs.

METHOD

CSF neurotensin concentrations were measured in 42 drug-free patients with schizophrenia or schizoaffective disorder. For 18 of these patients, CSF neurotensin was measure again after 4 weeks of antipsychotic treatment.

RESULTS

Significantly higher levels of pretreatment psychopathology were observed in the patients with the lowest CSF neurotensin concentrations. Furthermore, improvements in overall psychopathology and, particularly, negative symptoms were correlated with increases in CSF neurotensin concentrations during treatment.

CONCLUSIONS

These findings provide further evidence for a role of neurotensin the pathophysiology of psychosis and in the mechanism of action of antipsychotic drugs.

A two-phase, double-blind randomized study of three haloperidol plasma levels for acute psychosis with reassignment of initial non-responders

To clarify the plasma level/therapeutic response relationship of haloperidol (HPDL) we used a prospective double-blind design in 95 acutely psychotic patients. After drug washout, patients were randomly assigned to a low, middle or high plasma level range for 2 weeks (phase A), and then 50% of the initial non-responders were randomly reassigned into the putative therapeutic range for an additional 2 weeks (phase B). There were no significant differences in clinical outcome between the three plasma level ranges in phase A. However, in phase B initial non-responders displayed greater improvement in the middle range than in the low or the high ranges. No further benefit was observed when plasma levels were raised to or maintained in the high range.

Alteration of major cytokines produced by mitogen-activated peritoneal macrophages and splenocytes in T-2 toxin-treated male CD-1 mice

Fusarium T-2 toxin has immunotoxic properties that may be related to the modulation of cytokine expression by cells of the immune system. Male CD-1 mice were used to study the effect of in vivo exposure to T-2 toxin on the alteration of interleukin (IL)-1α, tumor necrosis factor α (TNF), and IL-6 in lipopolysaccharide-stimulated peritoneal macrophages, and IL-2, IL-3, and interferon γ (IFNγ) in concanavalin A (Con A)-stimulated splenocytes. Mice were orally dosed with 0, 0.1, 0.5, and 2.5 mg T-2 toxin/kg body weight for 2 weeks on alternate days. Northern blot analysis of IL-1α, TNF, and IL-6 mRNA from activated peritoneal macrophages showed no significant differences between control and treated groups. Measurements of secreted protein by immunoassay demonstrated suppression of these cytokines in all treated groups, suggesting that T-2 toxin affects the translational or post-translational regulation of these cytokines from peritoneal macrophages. Levels of IL-2, IL-3, and IFNγ mRNA from Con A-activated splenocytes were higher in all treated groups. The increases were significant for IL-2 and IFNγ in the groups receiving low (0.1 mg/kg) and high (2.5 mg/kg) doses of T-2 toxin, and for IL-3 in the group receiving a medium (0.5 mg/kg) dose of this toxin (P ≤ 0.05). Results indicated that T-2 toxin given orally at low or medium doses induces transcription or increases mRNA stability of IL-2, IFNγ, and IL-3. Protein levels of all three cytokines were also increased, indicating that T-2 toxin also increases translational/post-translational efficiency of IFNγ, IL-2, and IL-3. Possible mechanisms in the immunosuppressive effects of T-2 toxin may involve endotoxemia resulting after the toxin administration, alteration of the stability of mRNA, or previously described effects of T-2 toxin on protein synthesis.

Acute dietary tryptophan depletion: effects on schizophrenic positive and negative symptoms

Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) available for its synthesis, amounts of TRP in the diet may be manipulated to alter the corresponding levels of serotonin. This technique has been used for probing the role of serotonin in mediating various forms of pyschopathology. In this study, 16 patients meeting DSM III-R criteria for schizophrenia (n = 14) or schizoaffective disorder (n = 2) were assessed for the effects of acute dietary TRP depletion under controlled conditions. The hypothesis was that lowering of serotonin would result in a diminution of 'positive' and/or 'negative' symptoms of psychotic disorders. No clinically or statistically significant improvement compared to baseline occurred when TRP depletion was imposed. Indeed, there was a statistically significant deterioration on measures of negative symptoms. The results are discussed in the context of the methodological issues.

The effect of aflatoxin B1 on cytokine mRNA and corresponding protein levels in peritoneal macrophages and splenic lymphocytes

Male CD-1 mice were used to test the in vivo effects of aflatoxin B1 (AFB1) on the genetic expression of major cytokines produced by macrophages (interleukin (IL)- 1 alpha, IL-6 and tumour necrosis factor alpha (TNF)) and splenic lymphocytes (IL-2, interferon gamma (IFN gamma), and IL-3), activated in vitro with lipopolysaccharide (LPS) and concanavalin A (Con A), respectively. Animals were treated with 0, 0.03, 0.145 or 0.7 mg AFB1/kg body weight orally every other day for 2 weeks. No significant effects of the toxin on the weights of liver, kidney, spleen, or thymus, or in red blood cell counts were noted, but white blood cell counts were significantly elevated at the low (0.03 mg/kg) dose. Cytokine mRNA levels were measured by Northern blots or cDNA amplification and the secreted protein levels were measured by immunoassay. AFB1 had a marked effect on macrophage-produced cytokines. The mRNA levels increased significantly at the low (IL-1 alpha) or medium dose (IL-6 and TNF), their corresponding protein levels were generally suppressed. The levels of IL-1 alpha secreted protein were significantly suppressed at all dosages, and those of IL-6 and TNF at the high dose. The low dose of AFB1 slightly decreased both mRNA and protein levels of lymphocytic IL-2, IFN gamma, and IL-3, only IL-2 mRNA decreasing significantly (P < or = 0.05). It appears that AFB1 treatment preferentially affects macrophage functions, and in particular, it decouples the close correlation usually observed between transcriptional and translational controls of IL-1 alpha, IL-6 and TNF production by these cells.

An investigation of the mechanism of inhibition of the Ca(2+)-ATPase by phospholamban

The Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum has been reconstituted with peptides corresponding to the hydrophobic domain of phospholamban (PLB) with or without the three Cys residues replaced by Ala, and with PLB with the three Cys residues replaced by Ala [PLBcys-(1-52)]. Reconstitution with the hydrophobic domain of PLB[PLB(25-52)] was found to decrease the apparent affinity of the ATPase for Ca2+ with no effect on the maximal rate of ATP hydrolysis observed at saturating concentrations of Ca2+. Reconstitution with PLBCys-(1-52) decreased both the apparent affinity for Ca2+ and the maximal activity; the effect on maximal activity followed from a decrease in the rate of the Ca2+ transport step (E1PCa2-->E2P) as observed with the hydrophilic domain PLB(1-25). The concentration dependences of the effects of the hydrophobic domain and of the whole PLB molecule were very similar, suggesting that the hydrophilic domain made little contribution to the affinity of the ATPase for PLB. The effect of PLB on the ATPase was dependent on the molar ratio of phospholipid to ATPase, suggesting partition of the PLB between its binding site on the ATPase and the bulk lipid phase in the membrane. Neither PLB nor its hydrophobic domain affected the rates of phosphorylation or dephosphorylation of the ATPase. Despite their effects on the apparent affinity of the ATPase for Ca2+, neither PLB nor its hydrophobic domain had any effect on the true affinity of the ATPase for Ca2+, as measured from changes in the tryptophan fluorescence of the ATPase. The effects of PLB on the activity of the ATPase are the sum of the effects of its hydrophilic and hydrophobic domains.