Differentiation and apoptosis of human germinal center B-lymphocytes

An in vitro experimental model was developed to characterize the cellular and molecular factors that regulate germinal center (GC)-B-cell differentiation and apoptosis. In the culture system that sustains the GC-B-cell survival, CD40L stimulation is essential for GC-B-cell proliferation and differentiation in the presence of 1L-2, IL-4, and IL-10. IL-2 and Il-4 promote proliferation of GC-B-cells, whereas IL-10 is required for generation of plasma cells. Generation of memory B cells requires CD40L, IL-2, IL-4, but not IL-10. There are two mechanisms that cause apoptosis. In the early stage, spontaneous apoptosis occurs in the absence of CD40 stimulation. Following CD40L stimulation, Fas-mediated apoptosis operates to eliminate GC-B-cells, unless activated GC-B-cells encounter a second signal via B-cell Ig receptors. Physiological significance of these findings is discussed.

A robust approach to image enhancement based on fuzzy logic

In this paper, we propose a robust approach to image enhancement based on fuzzy logic that addresses the seemingly conflicting goals of image enhancement: (i) removing impulse noise, (ii) smoothing out nonimpulse noise, and (iii) enhancing (or preserving) edges and certain other salient structures. We derive three different filters for each of the above three tasks using the weighted (or fuzzy) least squares (LS) method, and define the criteria for selecting each of the three filters. The criteria are based on the local context, and they constitute the antecedent clauses of the fuzzy rules. The overall result of the fuzzy rule-based system is the combination of the results of the individual filters, where each result contributes to the degree that the corresponding antecedent clause is satisfied. This approach gives us a powerful and flexible image enhancement paradigm. Results of the proposed method on several types of images are compared with those of other standard techniques.

The effect of diphenyl-dimethyl-dicarboxylate on cyclosporine-A blood level in kidney transplants with chronic hepatitis

An adequate blood level of cyclosporine-A (CsA) is essential to keep graft function in kidney transplants. Due to a narrow therapeutic index and highly variable pharmacokinetic properties associated with CsA, drug interactions may have a significant impact on the immunosuppressive efficacy or toxicity of CsA. Numerous drug interactions of potential clinical significance involving CsA have been reported. Dephenyl-dimethyl-dicarboxylate (PMC), a hepatotonic drug, is a substance derived from the synthesis of Schizandrae fructus elements. We have experienced two cases of drug interaction between CsA and PMC in kidney transplants with chronic hepatitis. In both cases, CsA troughs decreased markedly to a subtherapeutic level following administration of PMC. We, therefore, suggest that PMC could decrease the CsA trough level and thus a close monitoring of the CsA trough level is necessary during a PMC therapy.

Involvement of the gallbladder in childhood metachromatic leukodystrophy: ultrasonographic findings

The purpose of this study was to analyze the peculiar involvement of the gallbladder in childhood metachromatic leukodystrophy. Seven consecutive children (four boys, three girls; age range, 9 to 58 months old; mean age, 24.3 months) with biochemically confirmed metachromatic leukodystrophy were studied with abdominal ultrasonography. Four of them showed abnormal findings, such as diffuse thickening of the gallbladder wall (more than 3 mm thick), sludge-like echogenic material, or papillary polypoid ingrowth of inner wall obliterating the lumen. In childhood metachromatic leukodystrophy, the characteristic abnormality of the gallbladder on ultrasonography may serve as an ancillary diagnostic clue to supplement the clinical and MR imaging findings, facilitating the differential diagnosis from the other, similar leukodystrophies.

CD48 delivers an accessory signal for CD40-mediated activation of human B cells

CD48, a glycosyl phosphatidylinositol anchored molecule has recently been shown to be a ligand for the T cell surface protein CD2 in mouse, human, and rat. It is expressed on practically all human T and B cells; however, its function remains unknown. We examined whether CD48 may be involved in the delivery of activating signals to human B cells. Costimulation with anti-CD48 J4-57 significantly increased CD40-mediated activation of tonsillar B cells. Costimulatory effect of anti-CD48 was observed on B cell aggregation, proliferation, and IgG secretion. Anti-CD48 alone did not stimulate resting B cells. Accessory signal provided through CD48 required the presence of IL-4 and/or IL-10, whereas responses of B cells to IL-2 was not affected. Ligation of CD48 by specific antibody induced CD23 expression on IL-4-stimulated Ramos B cell line but did not affect expression of CD25. We also examined the biochemical nature of the costimulatory effect of anti-CD40 and CD48. Ligation of CD40 or CD48 on the B cells induced tyrosine phosphorylation of proteins. CD40 induced earlier changes in the protein phosphorylation than CD48 did. Taken together, our data suggest that the stimulation via CD40 provides initial signals to activate B cells and CD48 may be involved in enhancing the activating signal to B cells, resulting in increased responsiveness of B cells to IL-4 and IL-10.

Up-regulation of Bcl-xL expression protects CD40-activated human B cells from Fas-mediated apoptosis

CD40--CD40L interactions between resting B cells and activated T cells are essential for germinal center formation. It has been shown that CD40L can induce both Fas expression and susceptibility to Fas-mediated killing in B cells, while anti-Ig can partially rescue B cells from Fas-mediated killing. However, the intracellular mechanism for this phenomenon is not known. We examined the expression of Fas and bcl-2 family gene products, such as Bcl-2, Bcl-x, Bax, and Mcl-1, in human tonsillar B cells. The activation of naive B cells by CD40L induced transient expression of Bcl-xL. As the Bcl-xL level decreased in CD40-activated B cells, the cells became susceptible to apoptosis by anti-Fas antibodies. Though anti-Ig did not change the Fas expression, it protected CD40-activated B cells from Fas-mediated killing by up-regulating Bcl-xL expression. The addition of anti-Ig did not significantly change Bcl-2, Bax, and Mcl-1 levels compared to those of B cells activated by CD40L alone.

Effects of intrathecally injected histamine receptor antagonists on the antinociception induced by morphine, beta-endorphin, and U50, 488H administered intrathecally in the mouse

The present study was designed to investigate the modulatory effects of blockade of spinal histamine receptors on antinociception induced by spinally administered morphine, beta-endorphin and U50, 488H. The effects of intrathecal (i.t.) injections with cyproheptadine (a histamine-1 (H1) receptor antagonist), ranitidine (an H2 receptor antagonist), or thioperamide (an H3 receptor antagonist) injected i.t., on the antinociception induced by morphine, beta-endorphin or trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl] benzeocetamide (U50, 488H) injected intrathecally (i.t.) were studied. The antinociception was assayed using the tail-flick test. The i.t. injection of cyproheptadine (20 micrograms), ranitidine (20 micrograms), or thioperamide (20 micrograms) alone did not produce any antinociceptive effect. i.t. pretreatment with cyproheptadine attenuated the inhibition of the tail-flick response induced by i.t. administered morphine or beta-endorphin, but not U50, 488H. In addition, i.t. pretreatment with ranitidine attenuated the inhibition of the tail-flick response induced by i.t. administered morphine, beta-endorphin, or U50, 488H. Furthermore, the i.t. pretreatment with thioperamide attenuated the inhibition of the tail-flick response induced by beta-endorphin or U50, 488H, but not morphine, administered i.t. Our results indicate that spinal H1 receptors may be involved in the production of antinociception induced by spinally applied morphine or beta-endorphin- but not U50, 488H. Spinal H2 receptors appear to be involved in spinally administered morphine-, beta-endorphin- and U50, 488H-induced antinociception. Supraspinal histamine H3 receptors may be involved in the production of antinociception induced by supraspinally applied beta-endorphin or U50, 488H, but not morphine.

Cellular and molecular factors that regulate the differentiation and apoptosis of germinal center B cells. Anti-Ig down-regulates Fas expression of CD40 ligand-stimulated germinal center B cells and inhibits Fas-mediated apoptosis

To investigate the molecular and cellular mechanisms underlying the selection, differentiation, and apoptosis of germinal center (GC) B cells, we have established a culture system containing a follicular dendritic cell (FDC) line, HK. The mAb, 3C8, which is specific to HK cells and recognizes dendritic network in the GC, was developed and provided additional evidence that HK cells are related to FDC by sharing a unique surface Ag. The roles for CD40 ligand (CD40L) and T cell-derived cytokines in the differentiation of GC B cells were investigated in our culture system. We show that there are two distinct stages of GC B cell differentiation. In the early stage, GC B cells undergo spontaneous apoptosis unless they are stimulated by CD40L. In the secondary stage, IL-10 directs GC B cell differentiation toward the generation of plasma cells, while the absence of IL-10 stimulation leads to the generation of memory B cells. The major function of CD40L was found in the enhancement of cell recovery and the augmentation of memory B cell generation. Although GC B cells are Fas+, GC B cells are at first resistant to, but then become sensitive to, anti-Fas killing after 24 h in culture with CD40L, which coincides with the gradual increase in Fas expression on GC B cells. Furthermore, anti-Ig down-regulated Fas expression on CD40L-stimulated GC B cells, suggesting that Ag receptor engagement down-regulates Fas expression and prevents Fas-mediated apoptosis of GC B cells. Our data imply that GC T cells have an important role in the differentiation and apoptosis of GC B cells. GC T cells expressing both CD40L and Fas ligand have a dual function on GC B cells, helper or killer, depending on the status of target B cells. In the early stage, GC T cells stimulate the extensive proliferation of GC B cells, ensuring a large repertoire of B cells for selection. In the later stage, GC T cells kill B cells via Fas-Fas ligand interactions unless GC B cells are positively selected by Ags present on FDC.

Cellular and molecular factors that regulate the differentiation and apoptosis of germinal center B cells. Anti-Ig down-regulates Fas expression of CD40 ligand-stimulated germinal center B cells and inhibits Fas-mediated apoptosis

To investigate the molecular and cellular mechanisms underlying the selection, differentiation, and apoptosis of germinal center (GC) B cells, we have established a culture system containing a follicular dendritic cell (FDC) line, HK. The mAb, 3C8, which is specific to HK cells and recognizes dendritic network in the GC, was developed and provided additional evidence that HK cells are related to FDC by sharing a unique surface Ag. The roles for CD40 ligand (CD40L) and T cell-derived cytokines in the differentiation of GC B cells were investigated in our culture system. We show that there are two distinct stages of GC B cell differentiation. In the early stage, GC B cells undergo spontaneous apoptosis unless they are stimulated by CD40L. In the secondary stage, IL-10 directs GC B cell differentiation toward the generation of plasma cells, while the absence of IL-10 stimulation leads to the generation of memory B cells. The major function of CD40L was found in the enhancement of cell recovery and the augmentation of memory B cell generation. Although GC B cells are Fas+, GC B cells are at first resistant to, but then become sensitive to, anti-Fas killing after 24 h in culture with CD40L, which coincides with the gradual increase in Fas expression on GC B cells. Furthermore, anti-Ig down-regulated Fas expression on CD40L-stimulated GC B cells, suggesting that Ag receptor engagement down-regulates Fas expression and prevents Fas-mediated apoptosis of GC B cells. Our data imply that GC T cells have an important role in the differentiation and apoptosis of GC B cells. GC T cells expressing both CD40L and Fas ligand have a dual function on GC B cells, helper or killer, depending on the status of target B cells. In the early stage, GC T cells stimulate the extensive proliferation of GC B cells, ensuring a large repertoire of B cells for selection. In the later stage, GC T cells kill B cells via Fas-Fas ligand interactions unless GC B cells are positively selected by Ags present on FDC.

Effects of GABA receptor antagonists injected spinally on antinociception induced by opioids administered supraspinally in mice

The present study was designed to investigate the modulatory effects of blockade of spinal GABAA and GABAB receptors on antinociception induced by supraspinally administered mu- and epsilon-opioid receptor agonists. The effects of intrathecal (i.t.) injections with GABAA and GABAB receptor antagonists, SR 95531 [2-(3-carboxypropyl)-3-amino-6-(4-mehylphenyl)pyridazinium bromide] and 5-aminovaleric acid, respectively, on the antinociception induced by morphine (a mu-opioid receptor agonist) and beta-endorphin (an epsilon-opioid receptor agonist) injected intracerebroventricularly (i.c.v.) were studied. Antinociception was assayed using the tail-flick test. The i.t. injection of SR 95531 (0.04-0.16 nmol) and 5-aminovaleric acid (32.5-130 nmol), administered alone did not affect the latencies of the tail-flick response, but selectively antagonized the inhibition of the tail-flick response induced by muscimol (a GABAA receptor agonist) and baclofen (a GABAB receptor agonist), respectively. The i.t. injection of SR 95531 attenuated dose-dependently the inhibition of the tail-flick response induced by i.c.v. administered morphine, without affecting the i.c.v. administered beta-endorphin-induced response. 5-Aminovaleric acid attenuated dose-dependently the inhibition of the tail-flick response induced by beta-endorphin, without affecting the response to i.c.v. administered morphine. Our results indicate that GABAA but not GABAB receptors located at the spinal cord appears to be involved in the antinociception induced by morphine administered supraspinally whereas GABAB but not GABAA receptors located at the spinal cord may be involved in the antinociception induced by supraspinally administered beta-endorphin, supporting further the hypothesis that morphine and beta-endorphin administered supraspinally produce their antinociception via the activation of different descending pain inhibitory systems.

Antinociceptive effect of smilaxin B administered intracerebroventricularly in the mouse

We examined the antinociceptive effect of smilaxin B administered intracerebroventricularly (i.c.v.) in ICR mice. The tail-flick test was used as an analgesic assay. Smilaxin B showed a strong antinociceptive effect in a dose-dependent manner. Sulfated cholecystokinin (CCK-8s, 0.5 ng), muscimol (50ng), or MK-801 [(+/-)-5-methyl-10, 11-dihydro-5H-dibenzo [a,d]cyclohepten-5, 10-imine maleate, 1 microgram] injected i.c.v. significantly reduced inhibition of the tail-flick response induced by smilaxin B administered i.c.v. However, naloxone (2 microgram), baclofen (10 ng), or CNQX (6-cyano-7- nitroquinoxaline-2,3-dione, 0.5 microgram) injected i.c.v. did not affect inhibition of the tail-flick response induced by similaxin B administered i.c.v. The intrathecal (i.t.) injection of yohimbine (20 micrograms), but not methysergide (20 micrograms) and naloxone (2 microgram), significantly attenuated inhibition of the tail-flick response. induced by smilaxin B administered i.c.v. Our results suggest that GABAA or NMDA receptors but not opioid, GABAB, and non-NMDA receptors located at the supraspinal level may play important roles in the production of antinociception induced by smilaxin B administered supraspinally. Furthermore, smilaxin B administered supraspinally. may produce its antinociception by activating descending noradrenergic- but not opioidergic- and serotonergic-neurons.

Interleukin-12 stimulates B cell growth by inducing IFN-gamma

Human interleukin-12 (IL-12) is a 70-kDa polypeptide that activates human natural killer cells. It has been purified from the culture supernatant of a human Epstein-Barr virus-transformed B cell line and cloned. We show that native as well as recombinant IL-12 promoted growth of Staphylococcus aureus Cowan I strain (SAC) or anti-mu antibody-activated B cells in a dose-dependent manner. IL-12 also acted in synergy with IL-2 in growth and differentiation of SAC-activated B cells. Since anti-interferon (IFN)-gamma antibody completely abrogates B-cell growth factor (BCGF) activity of IL-12, the BCGF activity is mediated by IFN-gamma. This conclusion is clearly supported by the results that IL-12 indeed induced IFN-gamma production by activated B cells. These results suggest that the B cell proliferative effect of IL-12 may be mediated by autocrine IFN-gamma.

Synthesis of sulfated octadecyl ribo-oligosaccharides with potent anti-AIDS virus activity by ring-opening polymerization of a 1,4-anhydroribose derivative

The synthesis and anti-AIDS virus activity of sulfated octadecyl ribofuranans with medium-range molecular weights have been investigated. Selective ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-alpha-D-ribopyranose with 10-20 mol% of boron triflouride etherate as a catalyst in a large amount of dichloromethane gave 2,3-di-O-benzyl-(1-->5)-alpha-D-ribofuranan in good yield. The molecular weight of the benzylated ribofuranan was in the range of 9 x 10(3) to 10 x 10(3). Debenzylation of the polymer followed by acetylation gave peracetylated (1-->5)-alpha-D-ribofuranans. The peracetylated ribofuranans were treated with octadecyl alcohol and a stannic chloride catalyst to afford acetylated ribofuranans having octadecyl groups at the reducing terminal. The molecular weights of the resulting acetylated octadecyl ribofuranans were below 9 x 10(3). Sulfation of the deacetylated octadecyl ribofuranans by piperidine-N-sulfonic acid in dry Me2SO gave sulfated octadecyl ribofuranans with molecular weights of 3 x 10(3) to 9 x 10(3) and sulfur contents of 13.0-16.2%. The sulfated octadecyl ribofuranans had potent anti-AIDS virus activity, EC50 = 0.6-2.5 micrograms/mL (a standard curdlan sulfate showed EC50 = 0.43 micrograms/mL), and low anticoagulant activity, 4-17 units/mg (a standard dextran sulfate, 22.7 unit/mg). Structural analysis of the ribofuranans was performed by NMR at 400 and 600 MHz.

Diethylumbelliferyl phosphate inhibits steroidogenesis by interfering with a long-lived factor acting between protein kinase A activation and induction of the steroidogenic acute regulatory protein (StAR)

Diethylumbelliferyl phosphate (DEUP) is an organophosphate cholesteryl ester hydrolase inhibitor that blocks steroidogenesis mainly by preventing cholesterol transport into the mitochondria of steroidogenic cells. In the present study, we show that DEUP blocks the cAMP-stimulated mitochondrial accumulation of the 30-kDa mitochondrial proteins (recently named steroidogenic acute regulatory StAR proteins) that are believed to be the cycloheximide-sensitive factors induced by trophic hormones and cAMP. Inhibition of mitochondrial StAR accumulation by DEUP is dose dependent and closely parallels inhibition of progesterone synthesis. Stimulated lactate production, another cAMP-dependent process in MA-10 cells, is also inhibited by DEUP. Inhibition of protein kinase A (PKA) action would explain the inhibition of these two unrelated processes. However, the cytosolic PKA activity of DEUP-treated MA-10 10 cells was normal. Moreover, the activity of purified PKA was unaffected by DEUP. The inhibition of StAR synthesis was not caused by a direct effect of DEUP on the labile proteins since DEUP-treated cells required more than 24 h to recover steroidogenic capacity after DEUP treatment. Further evidence that the synthesis of StAR was not directly affected was obtained using the constitutively active R2C cells. Progesterone synthesis by these cells also involves StAR, but neither StAR synthesis or steroid synthesis is sensitive to DEUP. Lactate formation in dibutyryl-cAMP-stimulated R2C cells is, however, sensitive to inhibition by DEUP. These data can be best explained by DEUP acting on a long-lived factor involved in the cAMP/PKA response pathway, but not involved in constitutive steroidogenesis.

Differential modulation by muscimol and baclofen on antinociception induced by morphine, beta-endorphin, D-Pen2,5-enkephalin and U50,488H administered intracerebroventricularly in the mouse

The present study was designed to investigate the modulatory effects of stimulation of GABAA and GABAB receptors at supraspinal sites on antinociception induced by supraspinally administered mu-, epsilon-, delta-, and kappa-opioid receptor agonists. The effects of the GABAA and GABAB receptor agonists, muscimol and baclofen respectively, on the antinociception induced by morphine (a mu-receptor agonist), beta-endorphin (an epsilon-receptor agonist), D-Pen2,5-enkephalin (DPDPE, a delta-receptor agonist) and U50,488H ([trans-3,4-dichloroN-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl] benzeocetamide]; a kappa-receptor agonist) injected intracerebroventricularly (i.c.v.) were studied. The antinociception was assayed using the tail-flick and hot-plate tests. Muscimol at doses of 25-200 ng, administered i.c.v. alone did not affect the latencies of tail-flick and hot-plate thresholds, but attenuated dose-dependently the inhibition of the tail-flick and hot-plate responses induced by i.c.v. administered morphine (2 micrograms), beta-endorphin (1 microgram), DPDPE (10 micrograms), and U50,488H (60 micrograms). Baclofen (1.25-10 ng) administered i.c.v. alone did not affect the latencies of the tail-flick and hot-plate responses, but attenuated dose-dependently the inhibition of the tail-flick and hot-plate responses induced by beta-endorphin and U50,488H, without affecting morphine- or DPDPE-induced responses. Our results indicate that activation of GABAA receptors at the supraspinal sites by i.c.v. injection of muscimol antagonizes antinociception induced by supraspinally administered mu-, epsilon-, delta-, and kappa-opioid receptor agonists. On the other hand, activation of GABAB receptors at supraspinal sites by i.c.v. baclofen antagonizes antinociception induced by i.c.v. administered epsilon- and kappa-opioid agonists, but not mu- or delta-opioid agonists.

Multiplicative interaction between intrathecally and intracerebroventricularly administered morphine for antinociception in the mouse: effects of spinally and supraspinally injected 3-isobutyl-1-methylxanthine, cholera toxin, and pertussis toxin

1. Either intrathecal (i.t.) or intracerebroventricular (i.c.v.) administration of morphine alone at the dose of 0.2 microgram slightly increased inhibition of the tail-flick response. However, combined i.t. and i.c.v. injections of morphine at the same dose increased the inhibition of the tail-flick response in a synergistic manner. 2. Cholera toxin (CTX, 0.05 to 0.5 microgram) pretreated i.t. or i.c.v. for 24 hr or pertussis toxin (PTX, 0.05 to 0.5 microgram) for 6 days dose-dependently attenuated inhibition of the tail-flick response induced by combined i.t. and i.c.v. injection of morphine. 3. 3-Isobutyl-1-methylxanthine (IBMX, 0.001 to 0.1 ng) pretreated i.t. for 10 min dose-dependently attenuated the inhibition of the tail-flick response induced by combined i.t. and i.c.v. injections of morphine. However, IBMX pretreated i.c.v. for 10 min was not effective in attenuating the inhibition of the tail-flick response induced by combined i.t. and i.c.v. injections of morphine. 4. It is concluded that both spinal and supraspinal CTX- and PTX-sensitive G-proteins are involved in the antinociception produced by morphine-induced multiplicative interaction between spinal and supraspinal sites. However, only spinal but not supraspinal cAMP phosphodiesterase is involved in mediating antinociception induced by morphine-induced multiplicative interaction.

Stimulation of germinal center B lymphocyte proliferation by an FDC-like cell line, HK

To identify the signals given to the germinal center (GC) B cells by FDC, we have established an FDC-like cell line, HK. HK cells have the important functions of FDC, which are the preferential binding and stimulation of GC B cells. Cell-cell interaction between IgD- B cells and HK cells resulted in the rescue of these cells from apoptosis, whereas the majority of unbound B cells or B cells cultured in the absence of HK cells underwent apoptosis. We investigated the effects of HK cells on the subpopulations of tonsillar B lymphocytes that are at different stages of maturation and differentiation. The subpopulations of tonsillar B cells were purified by panning and/or MACS according to the surface expression of IgD, CD38, and CD44. Although HK cells alone did not stimulate B cell proliferation, HK cells in the presence of either anti-mu or anti-CD40 significantly enhanced the proliferation of B cells. The data show that HK cells preferentially bind, rescue, and stimulate GC B cells (IgD-CD38+) generating CD38-CD44+ memory B cells. The costimulation activity of HK cells is also provided in a form of soluble factor(s). Hence, the phenotypic and functional analysis of HK cells suggests that these cells may be derived from FDC.

Stimulation of germinal center B lymphocyte proliferation by an FDC-like cell line, HK

To identify the signals given to the germinal center (GC) B cells by FDC, we have established an FDC-like cell line, HK. HK cells have the important functions of FDC, which are the preferential binding and stimulation of GC B cells. Cell-cell interaction between IgD- B cells and HK cells resulted in the rescue of these cells from apoptosis, whereas the majority of unbound B cells or B cells cultured in the absence of HK cells underwent apoptosis. We investigated the effects of HK cells on the subpopulations of tonsillar B lymphocytes that are at different stages of maturation and differentiation. The subpopulations of tonsillar B cells were purified by panning and/or MACS according to the surface expression of IgD, CD38, and CD44. Although HK cells alone did not stimulate B cell proliferation, HK cells in the presence of either anti-mu or anti-CD40 significantly enhanced the proliferation of B cells. The data show that HK cells preferentially bind, rescue, and stimulate GC B cells (IgD-CD38+) generating CD38-CD44+ memory B cells. The costimulation activity of HK cells is also provided in a form of soluble factor(s). Hence, the phenotypic and functional analysis of HK cells suggests that these cells may be derived from FDC.

Mucociliary activity and histopathology of sinus mucosa in experimental maxillary sinusitis: a comparison of systemic administration of antibiotic and antibiotic delivery by polylactic acid polymer

To evaluate the efficacy of antibiotic delivered by polyactic acid (PLA) polymer in sinusitis, we induced maxillary sinusitis in 32 New Zealand white rabbits by occluding the sinus ostium and inoculating the sinus cavity with Streptococcus pneumoniae. The rabbits were divided into three groups consisting of group 1 (control group, 8 rabbits), which was treated only by reopening the ostium; group 2, which was treated by both reopening the ostium and injecting ampicillin intramuscularly (40 mg/kg/day in three divided doses, 12 rabbits); and group 3 (12 rabbits) in which a piece of PLA-polymer ampicillin (0.326 mg) sheet (1.5 x 1.5 cm) was placed within the sinus after re-establishing ostial patency. The light microscopic findings such as epithelial ulceration, loss of cilia, infiltration of inflammatory cells, and edema were less pronounced in group 2 and minimal in group 3. The electron microscopic findings such as swelling of mitochondria and endoplasmic reticulum and protruded cytoplasm were severest in the control group, followed by groups 2 and 3. The mucociliary transport speed measured at the medial wall of the maxillary sinus was highest in group 3. The results of this study suggest that treatment with PLA-polymer ampicillin may have a better efficacy in maxillary sinusitis than that with systemic administration of ampicillin.

String editing analysis of human visual search

Eye movement (EM) data were recorded for human subjects performing a visual search task in a stereoscopic computer-generated three-dimensional scene. Each experimental run consisted of six presentations: three different object placements on a common background (quasi-natural scene) were used and one of the placements was repeated three additional times. Raw EM searchpath data were linearized, fixation points were defined via a fixation algorithm and, finally, strings of fixation region labels were obtained based upon a priori regionalization schemes. Use of string editing techniques allowed quantitative comparison of the similarity of various searchpaths. Analysis of the similarity of searchpaths for each subject, as well as across subjects, led us to conclude that presentation of repeated object placements caused each subject to develop a partly self-consistent, but idiosyncratic searchpath based upon a spatial model for that placement pattern.

Differential effects of 3-isobutyl-1-methylxanthine injected intrathecally or intracerebroventricularly on antinociception induced by opioids administered intracerebroventricularly in the mouse

Various doses of 3-isobutyl-1-methylxanthine (IBMX), a cAMP phosphodiesterase inhibitor, injected intrathecally (i.t.) or intracerebroventricularly (i.c.v.) alone did not show any antinociceptive effect. IBMX (0.01 to 1 ng) pretreatment i.t. for 10 min dose-dependently attenuated the inhibition of the tail-flick response induced by i.c.v. administered morphine (2 micrograms), beta-endorphin (1 microgram), and U50, 488H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl] benzeocetamide), 60 micrograms. However, pretreatment with IBMX i.c.v. did not affect the inhibition of the tail-flick response induced by morphine, beta-endorphin, and U50, 488H administered i.c.v. Neither i.c.v. nor i.t. pretreatment with IBMX attenuated the inhibition of the tail-flick response induced by D-Pen2-D-Pen5-enkephalin (DPDPE; 10 micrograms) administered i.c.v. Our results suggest that spinal but not supraspinal cAMP phosphodiesterases are involved in mediating antinociception induced by morphine, beta-endorphin and U50, 488H administered supraspinally. However, neither spinal nor supraspinal cAMP phosphodiesterase is involved in mediating antinociception induced by DPDPE administered supraspinally.