Effect of Syzygium aromaticum extract on immediate hypersensitivity in rats

We investigated the effect of aqueous extract of Syzygium aromaticum (L.) Merr. et Perry (Myrtaceae) flower bud (SAFB) on immediate hypersensitivity. SAFB inhibited compound 48/80-induced systemic anaphylaxis in rats (IC50 = 31.25 mg/kg, i.p.). SAFB also inhibited local immunoglobulin E (IgE)-mediated passive cutaneous anaphylactic reaction (IC50 = 17.78 mg/kg, i.v.; IC50 = 19.81 mg/kg, p.o.). When SAFB was pretreated at concentrations ranging from 25 to 1000 mg/kg, the serum histamine levels were reduced in a dose-dependent manner. Moreover, SAFB dose-dependently inhibited histamine release from rat peritoneal mast cells (RPMC) by compound 48/80 or anti-dinitrophenyl IgE. When SAFB was added, the level of cAMP in RPMC transiently and significantly increased about 47-fold at 10 s compared with that of basal cells. These results indicate that SAFB inhibits immediate hypersensitivity by inhibition of histamine release from mast cells in vivo and in vitro.

Activation of inducible nitric oxide synthase by Yongdam-Sagan-Tang in mouse peritoneal macrophages

The objective of the current study was to determine the effect of Yongdam-Sagan-Tang (YS-Tang) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with YS-Tang after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. YS-Tang had no effect on NO synthesis by itself. When YS-Tang was used in combination with rIFN-gamma, there was a marked co-operative induction of NO synthesis in a dose-dependent manner. The optimal effect of YS-Tang on NO synthesis was shown 6 h after treatment with rIFN-gamma. This increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. NO production was inhibited by NG-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus YS-Tang-stimulated cells was decreased by the treatment with staurosporin. In addition, synergy between rIFN-gamma and YS-Tang was mainly dependent on YS-Tang-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of YS-Tang were endotoxin free. These results suggest that the capacity of YS-Tang to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of YS-Tang-induced TNF-alpha secretion.

Brain-derived neurotrophic factor antisense oligonucleotide impairs memory retention and inhibits long-term potentiation in rats

We have examined the relationship between brain-derived neurotrophic factor gene expression in the hippocampus and memory retention as well as long-term potentiation of rats. One-way inhibitory avoidance learning was adopted as the behavioural paradigm. Results revealed that brain-derived neurotrophic factor messenger RNA levels in the dentate gyrus of the hippocampus were markedly increased at 1 h, 3 h and 6 h post-training in rats showing good retention performance when compared with the poor retention controls. Direct injection of brain-derived neurotrophic factor antisense oligonucleotide into the dentate gyrus of the hippocampus before memory consolidation takes place markedly impaired retention performance in rats. It also significantly decreased brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. The same antisense treatment also markedly reduced the amplitude and slope of excitatory postsynaptic potential as well as the brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. These results suggest that hippocampal brain-derived neurotrophic factor gene expression plays an important role in the memory consolidation process and in the expression of long-term potentiation in rats. These results provide the first evidence to relate brain-derived neurotrophic factor gene expression and memory function in vertebrates. It further suggests that brain-derived neurotrophic factor gene expression is involved in behavioural plasticity.

MPTP produces differential oxidative stress and antioxidative responses in the nigrostriatal and mesolimbic dopaminergic pathways

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to produce a differential toxicity in the nigrostriatal and mesolimbic dopaminergic pathways with the nigrostriatal pathway being more vulnerable. We, therefore, investigated whether oxidative stress and the antioxidant system play a role in this phenomenon. Balb/c mice were treated with either saline or MPTP (30 mg/kg/d) for 7 d, and were sacrificed on the next day. Results revealed that MPTP increased lipid peroxidation in the striatum (ST) and decreased glutathione concentration in the substantia nigra (SN) without markedly affecting these measures in the nucleus accumbens (NAc) and ventral tegmental area (VTA). Further, MPTP produced approximately twofold increases in both manganese superoxide dismutase (MnSOD) and copper-zinc superoxide dismutase (CuZnSOD) activities in the VTA while it only increased MnSOD activity in the SN. Both catalase and glutathione peroxidase (GPx) activities were not markedly altered by MPTP in both systems. However, the basal levels of catalase and GPx activities were higher in the VTA and NAc than in the SN and ST. These results together suggest that a lesser degree of oxidative damage and a more inducible CuZnSOD activity observed in the mesolimbic dopaminergic pathway may partially explain the differential toxicity MPTP produced in these two dopaminergic systems.

HCV and HBV coexist in HBsAg-negative patients with HCV viraemia: possibility of coinfection in these patients must be considered in HBV-high endemic area

Hepatocellular carcinoma (HCC) is one of the most common cancers and is highly associated with hepatitis B virus (HBV) infection in Korea. The role of HBV and hepatitis C virus (HCV) in HCC patients who are negative for hepatitis B surface antigens (HBsAg) remains poorly defined. It has been suggested that HCV core protein may impair the polymerase activity of HBV in vitro, potentially lowering HBV titre in coinfected patients. Therefore, routine enzyme immunoassay may not detect HBV, in spite of the presence of HBV viraemia in low titres. The aim of this study was to confirm the coexistence of HBV viraemia in hepatitis C-infected patients with HCC who have apparent HBsAg seronegativity and to establish the need for clinical reinterpretation of enzyme immunoassay (EIA) serological tests of HBsAg in patients with HCV viraemia and HCC. The serological profiles of HBV and HCV in 616 patients with HCC were analysed and the coinfection rate of HCV and HBV investigated. Sera were obtained from 16 patients who were both anti-HCV and HCV-RNA positive but HBsAg negative, and tested for HBV by polymerase chain reaction (PCR). Eleven non-A and non-B chronic hepatitis patients without HCC who had the same profiles of anti-HCV, HCV-RNA, and HBsAg were tested for HBV by PCR. As a control group, sera were obtained from 15 patients with HCC and 30 non-A and non-B chronic hepatitis patients without HCC; both were anti-HCV, HCV-RNA, and HBsAg negative and tested for HBV PCR. Of the 616 patients with HCC, 450 (73.1%) had current HBV infection, 48 (7.8%) had anti-HCV antibodies, and nine (1.5%) had viral markers of both HCV and HBV by serological profiles. Of the 27 patients with HCV viraemia and HBsAg seronegativity (16 with HCC; 11 with non-A non-B chronic hepatitis), 14 (51.9%) showed HBV viraemia by PCR. In contrast, of the 75 patients in the control group (45 with HCC; 30 with non-A and non-B chronic hepatitis) who were both HCV PCR negative and HBsAg negative, five (11.1%) showed HBV viraemia by PCR. The PCR for HBV revealed coexistent HBV viraemia in HCV viraemia patients, despite HBsAg negativity by EIA. In HBV-endemic areas, the possibility of coinfection of HBV in HBsAg-negative patients with HCV viraemia should be considered and molecular analysis for HBV-DNA performed.

Antianaphylactic properties of eugenol

The effects of eugenol, a major component of clove, on anaphylaxis were evaluated in rats. Eugenol inhibited compound 48/80-induced systemic anaphylaxis 100% with a dose of 10 micrograms g-1 body weight (BW). While serum levels of histamine were markedly elevated after compound 48/80 injection in all groups of rats, rats injected with eugenol showed a significant reduction in serum histamine levels. Eugenol also inhibited passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) IgE. Eugenol dose-dependently inhibited histamine release from the rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. The morphological examination clearly showed that eugenol prevented the anaphylactic degranulation of RPMC. Moreover, Eugenol (10 micrograms ml-1) had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha production. These results suggest that eugenol has antianaphylactic properties by preventing mast cell degranulation.

Spirulina platensis inhibits anaphylactic reaction

We investigated the effects of the powders of Spirulina platensis (SPP) on anaphylactic reactions. SPP inhibited compound 48/80-induced anaphylactic shock 100% with doses of 0.5, and 1.0 mg/g body weight (BW). SPP significantly inhibited serum histamine levels induced by compound 48/80 in rats. SPP (0.5 mg/g BW) inhibited to 68.7% passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) IgE. SPP dose-dependently inhibited the histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80. Moreover, SPP had a significant effect on anti-DNP IgE-induced histamine release or tumor necrosis factor-alpha production from RPMC. These results suggest that SPP may contain compounds with actions that inhibit mast cell degranulation in the rat.

Activation of inducible nitric oxide synthase by human choriogonadotropin in RAW 264.7 cells

Although human choriogonadotropin (hCG) plays a crucial role in the regulation of the menstrual cycle and maintenance of pregnancy, little is known about the other functions. However, recently hCG receptors have been identified in nongonadal cells. The objective of the current study was to determine the effect of hCG on the production of nitric oxide (NO). Stimulation of RAW 264.7 cells with hCG after treatment with recombinant interferon-gamma (rIFNgamma) resulted in increased NO synthesis. hCG had no effect on NO synthesis itself. NO production was inhibited by N(G)-monomethyl-L-arginine. rIFNgamma in combination with hCG showed marked increase of the expression of the inducible nitric oxide synthase (iNOS) gene. In addition, synergy between rIFNgamma and hCG was mainly dependent on hCG-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of hCG were endotoxin free. These results suggest that the capacity of hCG to increase NO production from rIFNgamma-primed RAW 264.7 cells is the result of hCG-induced TNF-alpha secretion.

Polarization properties of fiber lasers with twist-induced circular birefringence

We have experimentally observed and theoretically analyzed the polarization properties of fiber lasers with twist-induced birefringence. Twisting a fiber induces the circular birefringence of a fiber laser cavity, and this birefringence reduces the effects of intrinsic linear birefringence on the polarization properties of fiber lasers. The frequencies of their polarization eigenmodes coincide with each other gradually as the twist rate increases, and the directions of polarization eigenmodes deviate from the birefringence axis at a much larger twist rate than the magnitude of intrinsic linear birefringence. We describe the successful experimental results for Nd and Er fiber lasers.

Effect of the aqueous extract of Aquilaria agallocha stems on the immediate hypersensitivity reactions

We investigated the effects of the aqueous extract of Aquilaria agallocha Roxb. (Thymelaeaceae) on the immediate hypersensitivity reactions. The aqueous extract of Aquilaria agallocha stems showed inhibitory effects on passive cutaneous anaphylaxis, anaphylaxis induced by compound 48/80, and histamine release from rat peritoneal mast cells (RPMC). The morphological examination also clearly showed that the extract prevented the degranulation of RPMC in rats. The level of compound 48/80-induced intracellular cAMP in RPMC, when the extract was added, significantly increased about 8-fold at 10 s compared with that of basal cells. These results suggest that the aqueous extract of Aquilaria agallocha stems inhibits the immediate hypersensitivity reaction by inhibition of histamine release from mast cells.

Effect of cytochalasin D on systemic and local anaphylaxis in a murine model

We investigated the effect of cytochalasin D on anaphylaxis. Cytochalasin D dose-dependently inhibited systemic anaphylaxis induced by compound 48/80 in rats. Especially, cytochalasin D inhibited compound 48/80-induced systemic anaphylaxis 100% with a dose of 1 microg g-1 body weight (BW). Cytochalasin D significantly inhibited serum histamine levels induced by compound 48/80. Cytochalasin D (10(-1) microg g-1 BW) also inhibited local anaphylaxis activated by anti-dinitrophenyl (DNP) IgE to 79.6+/-1.8%. Cytochalasin D dose-dependently inhibited histamine release from the rat peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. The level of cAMP in rat peritoneal mast cells, when cytochalasin D was added, transiently and significantly increased about fourfold compared with that of basal cells. Our studies provide evidence that cytochalasin D will be beneficial in the treatment of anaphylaxis.

Anti-Ehrlichia chaffeensis antibody complexed with E. chaffeensis induces potent proinflammatory cytokine mRNA expression in human monocytes through sustained reduction of IkappaB-alpha and activation of NF-kappaB

Ehrlichia chaffeensis is an obligatory intracellular bacterium that infects monocytes and macrophages and is the etiologic agent of human ehrlichiosis in the United States. Our previous studies showed that the exposure of human monocytes to E. chaffeensis induces the expression of interleukin-1beta (IL-1beta), IL-8, and IL-10 genes in vitro but not the expression of tumor necrosis factor alpha (TNF-alpha) and IL-6 mRNAs. In this study, the effect of anti-E. chaffeensis antibody complexed with E. chaffeensis on the expression of major proinflammatory cytokines in human monocytes was examined. Human monocytic cell line THP-1 was treated with E. chaffeensis which had been preincubated with human anti-E. chaffeensis serum for 2 h, and the levels of cytokine mRNAs were evaluated by competitive reverse transcription-PCR. Anti-E. chaffeensis antibody complexed with E. chaffeensis significantly enhanced mRNA expression of IL-1beta in THP-1 cells. The expression of TNF-alpha and IL-6 mRNAs was also induced. The levels of secreted IL-1beta, TNF-alpha, and IL-6 during 24 h of stimulation were comparable to those induced by Escherichia coli lipopolysaccharide at 1 microg/ml. Fab fragment of anti-E. chaffeensis immunoglobulin G complexed with E. chaffeensis did not induce any of these three cytokines, indicating that ehrlichial binding is required for IL-1beta mRNA expression and that binding of the immune complex to the Fc gamma receptor is required for TNF-alpha and IL-6 mRNA expression and enhanced IL-1beta mRNA expression. Furthermore, prolonged degradation of IkappaB-alpha and activation of NF-kappaB were demonstrated in THP-1 cells exposed to anti-E. chaffeensis serum and E. chaffeensis. This result implies that development of anti-E. chaffeensis antibody in patients can result in the production of major proinflammatory cytokines, which may play an important role in the pathophysiology of ehrlichiosis and immune responses to it.

Inhibitory effects of Korean folk medicine 'Hi-Chum' on histamine release from mast cells in vivo and in vitro

The effect of aqueous extract of Siegesbeckia glabrescence (Compositae) whole plants (SGWP) on systemic or local anaphylaxis was studied. SGWP inhibited compound 48/80-induced systemic anaphylaxis 100% with a dose of 1000 mg/kg. Oral administration of SGWP (100 mg/kg) showed a marked inhibition rate in local immunoglobulin E (IgE)-mediated passive cutaneous anaphylaxis reaction. When SGWP was pretreated at concentration ranging from 0.1 to 1000 mg/kg, the serum histamine levels were reduced in a dose-dependent manner. Moreover, SGWP dose-dependently inhibited the histamine release from peritoneal mast cells by compound 48/80. These results indicate that SGWP possess strong antianaphylactic activity by inhibition of histamine release from mast cells.

An epidemiological study of developmental dysplasia of the hip in infants in Singapore

The incidence of congenital dislocation of the hip (CDH) in Singapore and Malaysia has been reported as being lower than in the West. In our hospital, we have seen an increasing number of congenital hip dislocation as well as dysplastic hips. We undertook a prospective study from December 1989 to December 1994 of 20,000 live births. The neonates were all screened by a consultant neonatologist and the findings were confirmed by a consultant paediatric orthopaedic surgeon. All babies had plain X-rays at 3 months and an acetabular index (AI) of 30 degrees or more was considered dysplastic. All babies with positive signs were followed up for 1 year and again had radiographs taken at 1 year. Comparison of plain X-rays and ultrasound assessment in a subgroup of 130 neonates showed that 64% of patients with AI > 20 degrees had hip dysplasia by ultrasonographic (alpha angle < 60 degrees) The incidence of dysplastic hips was 16.8 per 1000 live births. The overall incidence of neonates with dislocated hips was 4.7 per 1000 live births. The Malays were most affected with an incidence of 5.4 per 1000 live births. The incidence of developmental dysplasia of the hip in Singapore is higher than previously reported, with the Malays having the highest incidence. A significant number of babies with clicking hips have radiological evidence of acetabular dysplasia (AI > 30 degrees). One-third of the babies' hips were still dysplastic at 1 year of age. A well-organised screening programme with experienced examiners has proved to be useful in making early and accurate clinical diagnosis.

Identification of a novel glial fibrillary acidic protein mRNA isotype related to memory retention in rats

Using the polymerase chain reaction (PCR) differential display directed to cloning transcripts related to retention performance for the inhibitory avoidance learning task, we have isolated two rat cDNA fragments homologous to the 3' untranslated region (3'UTR) of glial fibrillary acid protein (GFAP) cDNA. The GFAP upper cDNA represents a new GFAP mRNA isotype which has a 7 bp insertion in the 3'UTR. Further analyses indicated that retention performance in rats containing only the new GFAP mRNA isotype was significantly better than that of rats containing both the new GFAP mRNA isotype and the standard GFAP mRNA simultaneously. These results suggest that expression of the GFAP isotypes may be related to memory retention in rats.

Ehrlichia sennetsu groE operon and antigenic properties of the GroEL homolog

A clone expressing an immunoreactive 55-kilodalton (kDa) protein of Ehrlichia sennetsu, the causative agent of human Sennetsu ehrlichiosis, was isolated from a gene library of this organism. Sequence analysis of the DNA insert revealed two open reading frames, encoding proteins of 10,620 and 58,225 kDa, respectively. These deduced amino acid sequences were homologous to those of the GroES and GroEL heat shock proteins (HSP) of other bacteria, respectively. Phylogenetic trees based on GroES and GroEL homologs of several bacteria including E. sennetsu showed a relationship similar to that based on 16S rRNA gene sequences. The recombinant and native 55-kDa proteins of E. sennetsu, GroEL homolog, reacted with a monoclonal antibody (SPA807) which recognizes a homologous sequence between human and mycobacterial HSP60 and a polyclonal antibody (SPA804) to cyanobacteria HSP60, but not with antibodies to HSP60 of several other organisms used. Furthermore, anti-recombinant E. sennetsu 55-kDa protein antibody prepared in a rabbit was reactive to HSP60 antigens of other Ehrlichia and Rickettsia species, but not GroEL of E. coli. The recombinant 55-kDa protein would be a useful tool for studying the role of this antigen in the immune response to E. sennetsu infection.

Antisense oligonucleotides to corticotropin-releasing factor impair memory retention and increase exploration in rats

Corticotropin-releasing factor is known as a stress peptide which stimulates adrenocorticotropin and corticosterone release. It also has a direct central effect to produce various behavioural activations in rats. In the present study, we have designed and studied the effects of an antisense oligonucleotide directed against the corticotropin-releasing factor gene in rats. Local injection of this antisense oligonucleotide into the hippocampus (1 nmol, five injections) significantly impaired the retention performance of an inhibitory avoidance task in rats. In another experiment, the same injection (1 nmol, four injections) also markedly increased rearing response and total distance travelled by rats in a novel activity chamber. Meanwhile, it markedly decreased grooming behaviour in rats. When directly injected into the hypothalamus in another group of animals (1 nmol, four injections), this antisense oligonucleotide significantly decreased the plasma adrenocorticotropin level. The effectiveness of these antisense oligonucleotide treatments was verified by a significant reduction in the level of corticotropin-releasing factor messenger RNA in specific brain regions as determined by quantitative reverse transcription polymerase chain reaction analysis. These results strengthen the importance of corticotropin-releasing factor in modulating memory processing and exploratory behaviour in rats. This work also provides an important tool for studying other physiological functions that corticotropin-releasing factor may mediate or modulate in mammals.

Ehrlichia chaffeensis inclusions are early endosomes which selectively accumulate transferrin receptor

Ehrlichia chaffeensis is an obligatory intracellular bacterium which infects macrophages and monocytes. Double immunofluorescence labeling was used to characterize the nature of E. chaffeensis inclusion in the human promyelocytic leukemia cell line THP-1. E. chaffeensis was labeled with dog anti-E. chaffeensis serum and fluorescein isothiocyanate-conjugated anti-dog immunoglobulin G (IgG). Lissamine rhodamine-conjugated anti-mouse IgG was used to label various mouse monoclonal antibodies. Ehrlichial inclusions did not fuse with lysosomes, since they were not labeled with anti-CD63 or anti-LAMP-1. The ehrlichial inclusions were slightly acidic, since they weakly accumulated 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine and stained weakly positive for vacuolar type H+ ATPase. Some ehrlichial inclusions were labeled positive with antibodies against HLA-DR, HLA-ABC, and beta2 microglobulin, while other inclusions in the same cell were labeled negative. The inclusions were labeled strongly positive for transferrin receptors (TfRs) and negative for the clathrin heavy chain. Time course labeling for TfRs showed that up to 3 h postinfection, most of the ehrlichial inclusions were negative for TfRs. After 6 h postinfection, 100% of the ehrlichial inclusions became TfR positive and the intensity of labeling was increased during the subsequent 3 days. Reverse transcription-PCR showed a gradual increase in the level of TfR mRNA postinfection, which reached a peak at 24 h postinfection. These results suggest that ehrlichial inclusions are early endosomes which selectively accumulate TfRs and that the ehrlichiae up-regulate TfR mRNA expression.

Suppression of L-histidine decarboxylase mRNA expression by methyleugenol

We investigated the effect of methyleugenol on anaphylaxis. Methyleugenol completely inhibited systemic anaphylaxis induced by compound 48/80 in mice. Methyleugenol also inhibited local anaphylaxis activated by anti-dinitrophenyl (DNP) IgE. Moreover, methyleugenol dose-dependently inhibited histamine release in mast cells activated by compound 48/80 or anti-DNP IgE. Northern-blot analysis demonstrated that significantly reduced level of the mRNA of L-histidine decarboxylase (HDC) was expressed in mast cells treated with methyleugenol, compared to that without methyleugenol. We conclude that methyleugenol directly affect histamine release and HDC gene over-expression in mast cells.

Identification of a rat brain gene associated with aging by PCR differential display method

The polymerase chain reaction (PCR) differential display method is a powerful tool to detect and characterize alteration of gene expression in eukaryotic cells. In order to screen the differentially expressed genes between the adult (3 mo) and aged (24 mo) rats, the PCR differential display method was adopted in the present study. One differentially expressed cDNA band (C7-1) was identified and the aged rats expressed more the C7-1 gene than the adult rats in the frontal cortex, but not in the hippocampus and hypothalamus. The C7-1 cDNA band was recovered, reamplified, and subcloned as a probe in Northern blot analysis. A transcript of approx 2.8 kb was expressed in the frontal cortex of both the adult and aged rats, but the C7-1 mRNA level was increased for 52% in the aged rats. The C7-1 gene was then sequenced that contains 243 bp. We have found that the C7-1 cDNA shows no significant homology to any published genes, suggesting that the C7-1 gene is an unknown gene associated with aging. This study provides the first evidence to show that there is alteration in gene expression associated with aging by using the PCR differential display method.

Evaluation of a gel-immunization technique used with two different Immucox vaccine formulations in battery and floor-pen trials with broiler chickens

The use of a gel-immunization technique with Immucox vaccination was compared and evaluated against other immunization methods in battery and floor-pen immunization trials. Gel immunization was found to be superior to immunization by gavage, by spray cabinet, or by the conventional delivery method of Immucox in a battery trial. Significantly enhanced protection as measured by weight gain, coupled with the establishment of a more uniform primary immunizing infection as evidenced by greater intestinal lesions and increased oocyst shedding, was seen in gel-immunized birds. In addition, cross-protective battery trials determined that the strain of Eimeria maxima found in the Immucox vaccine failed to elicit protection against a recent field isolate of E. maxima as measured by average weight gain and lesion scores. A reformulation of the Immucox vaccine that included the field isolate of E. maxima was required to elicit a protective immune response against challenge by the field strain. A floor-pen experiment demonstrated that gel immunization of 1-day-old roaster chickens resulted in performance parameters of average weight gain, average bird weight, and feed conversion that did not differ significantly from those recorded for medicated nonimmunized birds.

Absence of tumor necrosis factor alpha, interleukin-6 (IL-6), and granulocyte-macrophage colony-stimulating factor expression but presence of IL-1beta, IL-8, and IL-10 expression in human monocytes exposed to viable or killed Ehrlichia chaffeensis

Ehrlichia chaffeensis is a recently isolated minute gram-negative obligatory intracellular bacterium of monocytes/macrophages and is the etiologic agent of human monocytic ehrlichiosis. It is not known how macrophages respond when they encounter ehrlichiae in terms of cytokine production. In this study, we examined cytokine mRNA expression by incubating E. chaffeensis with THP-1 cells and performing competitive reverse transcription-PCR (RT-PCR). At 2 h postinfection, the levels of interleukin-1beta (IL-1beta), IL-8, and IL-10 mRNAs were significant but lower than those following Escherichia coli lipopolysaccharide (LPS) stimulation. Unlike the situation with E. coli LPS stimulation, however, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF-alpha) mRNAs were not induced. Time course and dose-response studies confirmed the absence of IL-6, GM-CSF, and TNF-alpha mRNA induction with E. chaffeensis. Viable E. chaffeensis organisms were not required for IL-1beta IO, IL-8, and IL-10 mRNA induction, since heat-killed E. chaffeensis induced identical time course responses. IL-1beta, IL-8, and IL-10 mRNAs were detected for up to 21, 21, and 24 h postexposure with E. chaffeensis, respectively, which were shut off more rapidly than with LPS stimulation. Although heat treatment of E. chaffeensis had no effect, periodate treatment completely abolished the ability of E. chaffeensis to induce IL-1beta, IL-8, and IL-10 mRNAs. The capture enzyme-linked immunosorbent assay result corresponded with the RT-PCR results, showing that viable and heat-killed E. chaffeensis produced and secreted the same levels of IL-1beta and IL-8. IL-10 production was significantly reduced by heat treatment. Periodate-treated ehrlichiae did not induce production of any of the cytokines tested. Anti-CD14 monoclonal antibody and polymyxin B did not inhibit IL-1beta mRNA expression upon exposure to E. chaffeensis. The absence of TNF-alpha, IL-6, and GM-CSF mRNA induction may delay the development of a protective immune response, thereby allowing E. chaffeensis to set up residence in macrophages.

The mesolimbic dopaminergic pathway is more resistant than the nigrostriatal dopaminergic pathway to MPTP and MPP+ toxicity: role of BDNF gene expression

In the present study we examined the role of BDNF gene expression involved in the differential vulnerability of the nigrostriatal and mesolimbic dopaminergic pathways to environmental damage. The toxins for dopamine (DA) neurons 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP+) were used as pharmacological tools. Results revealed that chronic MPTP treatment produced a significant and irreversible DA depletion in the striatum (ST) as well as a marked decrease in tyrosine-hydroxylase (TH) mRNA level in the substantia nigra (SN). Under these conditions, the endogenous brain-derived neurotrophic factor (BDNF) mRNA level was increased in the SN. Only acute DA reduction was found in the nucleus accumbens (NAc) and TH mRNA level was not affected in the ventral tegmental area (VTA) by MPTP treatment. Further, when MPP+ produced a similar extent of DA depletion in the ST and NAc, the TH mRNA level was also decreased while BDNF mRNA level was increased in the SN. The same alterations were not observed in the VTA. Results from the BDNF mRNA regional distribution study revealed that structures in the mesolimbic dopaminergic pathway expressed a more than 2-fold higher basal BDNF mRNA level than structures in the nigrostriatal dopaminergic pathway. Presumably, enhanced BDNF gene expression would help the survival of DA neurons and these findings suggest a better protective mechanism in the mesolimbic pathway. Lastly, direct BDNF infusions to the SN partially protected against MPTP's toxicity on DA neurons in the ST in mice. These results together suggest that a more abundant BDNF mRNA level along the mesolimbic pathway than the nigrostriatal pathway may, at least partially, explain the differential vulnerability of different DA neurons to MPTP and MPP+ toxicity.

A rob-like gene of Enterobacter cloacae affecting porin synthesis and susceptibility to multiple antibiotics

A chromosomal gene of Enterobacter cloacae affecting the synthesis of major outer membrane proteins in E. cloacae and Escherichia coli was cloned by using selection for resistance to cefoxitin in E. coli. The presence of the gene, when plasmid-borne, led to a decrease in the amount of porin F in E. cloacae and the amount of OmpF in E. coli and caused 2- to 32-fold increases in the MICs of chloramphenicol, tetracycline, quinolones, and beta-lactam antibiotics. The gene encoded a 33-kDa protein, similar (83% identity) to the protein Rob involved in the initiation of DNA replication in E. coli, which was called RobA(EC1) by analogy. RobA from E. cloacae was found to inhibit ompF expression at the posttranscriptional level via activation of micF, a gene also apparently present in E. cloacae, as detected by PCR. As with its homolog from E. coli, RobA(EC1) is related to the XylS-AraC class of positive transcriptional regulators, along with MarA and SoxS, which also cause a micF-mediated decrease in the level of ampF expression.

Circadian rhythm in the Ca(2+)-inhibitable adenylyl activity of the rat striatum

In the present study, we demonstrate that the Ca(2+)-inhibitable adenylyl cyclase (AC) activity in the striatum exhibits a daily oscillation with a peak occurring around 10:00 h. A circadian fluctuation of the AC activity evoked by an A2a adenosine-selective agonist was also observed. Intrastriatal injection of an A2a-selective adenosine agonist or antagonist during the interval in which the Ca(2+)-inhibitable AC activity was at its peak resulted in a more significant alteration of locomotor activity than those observed at a later interval. The marked circadian variation in the Ca(2+)-inhibitable AC activity in the striatum appears to cause a circadian fluctuation in the action of at least one neuromodulator.

Characterization of L-DOPA transport in cultured rat and mouse astrocytes

The present work studied the transport of L-DOPA in cultured rat and mouse astrocytes. Results indicated that the uptake of L-[14C]DOPA in both rat and mouse astrocytes was Na+ independent and temperature sensitive. It was mediated by a carrier-mediated mechanism with Km values of 36 and 60.3 microM, and V(max) values of 2.4 and 1.9 nmol/min/mg protein for rat and mouse cells, respectively. L-DOPA uptake was potently inhibited by aromatic or branched-chain amino acids. Interestingly, the release of intracellular L-[14C]DOPA was also trans stimulated by competitors that affect L-DOPA uptake. The 14C recovered in the 2-min uptake process was identified as L-[14C]DOPA. However, [14C]dopamine (DA) was also detected in both rat and mouse astrocytes after 30 min L-DOPA incubation, indicating the existence of aromatic L-amino acid decarboxylase (AADC). Taken together, L-DOPA was uphill transported into rat and mouse astrocytes by a (Na+) -independent exchanger with preference for aromatic and branched-chain amino acids. Rat astrocytes possessed higher affinity for L-DOPA uptake than mouse astrocytes. Both cells synthesized DA from exogenous L-DOPA. Thus, astrocytes serve not only as a temporary storage site for L-DOPA but also as a DA-producing machinery. These results may be of particular importance to parkinsonian patients under L-DOPA medication.

Effects of enhanced O3 and CO2 enrichment on plant characteristics in wheat and corn

The effects of CO(2) enrichment and O(3) induced stress on wheat (Triticum aestivum L.) and corn (Zea mays L.) were studied in field experiments using open-top chambers to simulate the atmospheric concentrations of these two gases that are predicted to occur during the coming century. The experiments were conducted at Beltsville, MD, during 1991 (wheat and corn) and 1992 (wheat). Crops were grown under charcoal filtered (CF) air or ambient air + 40 nl liter(-1) O(3) (7 h per day, 5 days per week) having ambient CO(2) concentration (350 microl liter(-1) CO(2)) or + 150 microl liter(-1) CO(2) (12 h per day.). Averaged over O(3) treatments, the CO(2)-enriched environment had a positive effect on wheat grain yield (26% in 1991 and 15% in 1992) and dry biomass (15% in 1991 and 9% in 1992). Averaged over CO(2) treatments, high O(3) exposure had a negative impact on wheat grain yield (-15% in 1991 and -11% in 1992) and dry biomass (-11% in 1991 and -9% in 1992). Averaged over CO(2) treatments, high O(3) exposure decreased corn grain yield by 9%. No significant interactive effects were observed for either crop. The results indicated that CO(2) enrichment had a beneficial effect in wheat (C(3) crop) but not in corn (C(4) crop). It is likely that the O(3)-induced stress will be diminished under increased atmospheric CO(2) concentrations; however, maximal benefits in crop production in wheat in response to CO(2) enrichment will not be materialized under concomitant increases in tropospheric O(3) concentration.

Biomechanical study on tibialis posterior tendon transfers

Two methods are used to route the tibialis posterior tendon anteriorly to achieve dorsiflexion: (1) around the medial side of the tibia, or the subcutaneous route; and (2) through the interosseous membrane, or the interosseous route. This study determined the effect of site of tendon insertion on ankle and foot motions and compared the efficacy of both routes. Eleven fresh normal cadaveric legs were used. The detached tibialis posterior tendon was transferred anteriorly through the interosseous membrane and anchored to the first cuneiform along the first metatarsal axis by a barbed staple. The specimen was mounted on a mechanical testing machine. Tension was applied to the tendon and ankle and foot motions were measured. The experimental procedure was repeated with tendon insertion along the second metatarsal axis and serially through to the fifth metatarsal axis. The entire experiment was repeated using the subcutaneous route. The interosseous route was more effective in achieving maximum dorsiflexion with minimal pronation. Shifting the insertion medially caused supination, whereas a more lateral insertion caused pronation.

1-Methyl-4-phenyl-pyridinium (MPP+) uptake does not explain the differential toxicity of MPP+ in the nigrostriatal and mesolimbic dopaminergic pathways

The present study examined the possible differential toxicity of 1-methyl-4-phenyl-pyridinium (MPP+) in the nigrostriatal and mesolimbic dopaminergic pathways in BALB/c mice, and investigated whether MPP+ uptake may account for this differential toxicity. Results indicated that chronic MPP+ infusions to the striatum (ST) and nucleus accumbens (NAc) both produced a toxicity on dopamine (DA) neurons. However, MPP+ produced a more severe DA depletion in the ST than in the NAc. Kinetic analyses from MPP+ uptake studies revealed a similar Km value in both the ST and NAc, suggesting that the affinity for MPP+ uptake is not different. The Vmax was approximately 1.6-fold higher in the ST than in the NAc. These results together suggest that chronic MPP+ infusions produce a differential toxicity on DA neurons in the nigrostriatal and mesolimbic dopaminergic pathways and that the ability of MPP+ uptake in DA terminals probably does not account for this differential toxicity.

Nicotine enhances brain biopterin concentration in rats

The dose-response and time-course effects of acute nicotine on total biopterin concentrations in the striatum, hypothalamus and hippocampus were examined in rats by using high performance liquid chromatography (HPLC) with fluorescence detection. Results indicated that across a wide dose range, only 0.5 mg/kg nicotine (free base) significantly increased biopterin level in the striatum and the hypothalamus, but not in the hippocampus. The time-course results revealed that the optimal time point for nicotine to exert this effect is around 30 min after systemic injection. These results suggest that nicotine may enhance catecholamine synthesis in these areas. It further implies that nicotine may alleviate the symptom of motor dysfunction as observed in certain neurological diseases.

Alteration of corticotropin-releasing factor immunoreactivity in MPTP-treated rats

A decrease of corticotropin-releasing factor (CRF) concentration has been reported in patients with Parkinson's disease (PD). The present study further examined the role of CRF in an animal model of parkinsonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Results indicated that both subchronic (2 days) and chronic (7 days) MPTP treatments decreased the number of CRF immunoreactive neurons in both the paraventricular nucleus (PVN) of the hypothalamus and the central nuelcus of the amygdala (ACN). This effect lasted for almost a month after withdrawal of chronic MPTP injections. In addition, nomifensine pretreatment protected against MPTP's toxicity on DA neurons, as assessed by tyrosine hydroxylase immunoreactivity in the substantia nigra. However, the same treatment did not prevent the toxicity of MPTP on CRF neurons. Further, no significant difference was notable in the number of CRF immunoreactive neurons between normal young adult and normal middle-aged rats in both the PVN and the ACN. These results suggest that MPTP also produces a neurotoxicity on CRF neurons, and this effect is not secondary to MPTP's effect on DA neurons. Besides, altered CRF neuronal activity is involved in the process of pathological ageing, but not physiological ageing. Further, reduced CRF immunoreactivity in the PVN and ACN may imply alterations of neuroendocrine, autonomic as well as central functions caused by MPTP.

Biological and immunological comparisons of Enterobacter cloacae and Escherichia coli porins

Bacteriocin susceptibilities indicate that during cloacin DF13 uptake the F porin of Enterobacter cloacae plays a similar role to that reported for the OmpF porin of Escherichia coli during colicin A entry. The translocatory activities of these two porins during the bacteriocin uptake can be substituted by the porins D and OmpC, respectively, under conditions not requiring the receptor binding step. Using anti-peptide antibodies, a peptide located in the internal loop L3 of the Escherichia coli OmpF porin was identified in the D and F porins of Enterobacter cloacae. The results demonstrated the existence of a close relationship between porins in terms of both antigenic determinants and bacteriocin susceptibilities.

Intracellular acidosis decreases the outward Na(+)-Ca2+ exchange current in guinea pig ventricular myocytes

The Na(+)-Ca2+ exchange transport operating in outward mode has been suggested to cause Ca2+ entry during reperfusion or reoxygenation, exchanging extracellular Ca2+ for intracellular Na+ that has accumulated during ischemia or cardioplegia. During cardioplegia, however, an increase in Ca2+ entry via this mechanism can be decreased due to increased intracellular H+ activity and a decrease in cellular ATP content. In this study giant excised cardiac sarcolemmal membrane patch clamp technique was employed to investigate the effect of cytosolic pH change on the Na(+)-Ca2+ exchanger, excluding the effect of ATP, in guinea pig cardiac myocytes. The outward Na(+)-dependent current, which has a characteristics of Hill equation, was decreased as pH was decreased in the range of 7.5-6.5. The current density generated by the Na(+)-Ca2+ exchange transport was 56.6 +/- 4.4 pA/pF (Mean +/- S.E.M.) at pH 7.2 and decreased to 42.9 +/- 3.0 pA/pF at pH 6.9. These results imply that Na(+)-Ca2+ exchange transport, operating in a reverse mode during cardioplegia, decreases due to increased intracellular H+, and further suggest that consequent intracellular Na+ accumulation is one of aggravating factors for Ca2+ influx during reoxygenation or reperfusion.

Planar optical configurations for crossover interconnects

Two planar optics configurations for crossover interconnects are described, and the interconnection capacity of each configuration is derived on the basis of Gaussian beams' being relayed by microlens arrays. To reduce the optical path differences between bypass- and exchange-connection routes in the crossover configurations, we propose the use of two different substrates.

Accentuation of gas exchange gradients in flushes of ponderosa pine exposed to ozone

Two-year-old ponderosa pine seedlings (Pinus ponderosa Laws.) were exposed to episodic O(3) concentrations in open-top chambers for two consecutive growing seasons (June through September of 1990 and 1991). Near the end of the second season of O(3) exposure, gas exchange was measured on needles of surviving flushes at saturating CO(2) and photosynthetic photon flux density (PPFD). Both photosynthetic capacity (A(sat)) and stomatal conductance to water vapor (g(wv)) declined linearly with needle age but differences within a flush were also found. Gas exchange rates of needles from the base of the current-year flush were significantly lower than those of needles from the top of the flush, even though age differences between needles were negligible. Although most measurements were conducted at saturating CO(2), similar patterns of gas exchange were also found at 350 micro mol mol(-1) CO(2), indicating that photosynthesis of needles at the bottom of the flush was more strongly affected by O(3) than that of needles at the top of the flush, even though the potential for O(3) uptake was probably less in needles at the bottom of the flush because of reduced stomatal conductance. Carboxylation efficiency (deltaA/deltaC(i)), the linear slope of the A/C(i) response, was highly correlated with A(sat), varying with needle age, needle position in the flush and O(3) exposure, but the magnitude of the reductions was greater than for A(sat). We conclude that susceptibility to O(3) damage among needles of an individual seedling varies not only with needle age but also with needle position, and that reductions in photosynthetic capacity may not be directly attributable to increased uptake of the pollutant. The data also indicate the need to consider within-flush variation when estimating whole-plant carbon gain and O(3) uptake.

Role of hippocampal nitric oxide in memory retention in rats

The present study investigated the role of hippocampal nitric oxide (NO) in memory retention of an inhibitory avoidance learning task in rats. The anatomical locus was aimed at the dentate gyrus (DG). Results indicated that intra-DG administration of a NO generator, sodium nitroprusside (SNP), at moderate doses enhanced retention performance in a dose-response fashion in rats. SNP at higher doses, on the other hand, impaired memory retention. Intra-DG injection of a NO inhibitor, L-NG-monomethylarginine (L-MeArg), impaired retention performance at moderate doses. Coadministration of a NO precursor L-arginine (2.9 and 7.2 micrograms) reversed the memory-impairing effect of L-MeArg. An in vitro ADP-ribosylation experiment showed five protein bands with molecular weights around 118, 94, 54, 43, and 39 kDa that were labeled. The labeling intensity of these proteins decreased as the concentration of in vivo SNP increased. These results suggest that hippocampal NO plays a facilitatory role in the memory process of an inhibitory avoidance learning task in rats.

Amphetamine enhances memory retention and facilitates norepinephrine release from the hippocampus in rats

The present study investigated the effects of intrahippocampal amphetamine on memory retention and the role of hippocampal norepinephrine (NE) in memory consolidation in rats. One-way inhibitory avoidance learning paradigm was adopted. Animals were trained to avoid the foot shock. The latency to step into the shock compartment was recorded as the retention measure. The ceiling score (full retention) was 600 s. Results indicated that intra-hippocampal injections of amphetamine produced a dose-dependent enhancement of memory retention with doses at 0.6 micrograms and 1.6 micrograms reaching a significant effect. The beta-adrenergic blocker propranolol, at a dose which did not affect retention alone (80 ng), antagonized the memory-enhancing effect of amphetamine. Along with this memory-enhancing effect, amphetamine also elevated the level of NE release, and this effect was significant in animals not showing a full retention score (nonresponders) than in animals showing a full retention score (responders), as assayed by in vivo microdialysis. Within the control group, the responders also had a higher level of NE than the nonresponders. All these results are probably due to the fact that responders have a higher level of NE release than nonresponders. The effect of amphetamine on NE release is, therefore, not as obvious in responders. These results together support our hypothesis that NE plays a facilitatory role in the memory process and amphetamine enhances retention performance, at least in part, through facilitation of hippocampal NE release.

Impaired retention by angiotensin II mediated by the AT1 receptor

We demonstrated previously that hippocampal dentate gyrus neurons were sensitive to angiotensin II (AII) and recently discovered that AII applied directly to the dentate gyrus inhibited granule cell long-term potentiation induction and that the inhibition is mediated by the AT1 receptor and can be blocked by losartan, a specific AT1 antagonist. The purpose of the present study was to examine the effects of AII administered directly to the dentate gyrus, 1, 5, 50, 150, and 300 ng, on the retention of an inhibitory shock avoidance response and to determine if the resultant impairment of retention can be blocked by losartan. A total of 12 groups of rats in three experiments were studied. Three independent repetitions of 5 ng AII administered bilaterally to the dentate gyrus demonstrate a clear impairment of retention under these experimental conditions and that the impairment can be effectively prevented by pretreatment with 20 mg/kg of losartan IP.