Peripheral neuroblastoma in a young Beagle dog

A peripheral neuroblastoma was found in the abdominal cavity of a young male beagle dog. The large tumor mass involved the left kidney and both adrenal glands. Histologically, a major portion of the neoplasm consisted of lobulated sheets of small round cells with hyperchromatic nuclei mixed with polygonal cells and neuropil. Small clusters of polygonal cells with abundant eosinophilic cytoplasm and a trabecular growth pattern were observed adjacent to some of the tumor lobules. Small, round neoplastic cells metastasized to lumbar lymph nodes and also to the adrenal glands. The neoplastic cells were positive for neuron-specific enolase, synaptophysin, and neurofilament protein. Electron micrographs revealed intracytoplasmic dense core granules, microtubules, intermediate filaments, and desmosomes in the cytoplasm of the neoplastic cells.

Antibacterial activity of cured dental resin incorporating the antibacterial monomer MDPB and an adhesion-promoting monomer

In this study, the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) and an adhesion-promoting phosphoric monomer were incorporated into Bis-GMA-based dental resin and its antibacterial activity after curing was investigated. The experimental resin containing MDPB and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was polymerized and washed with methanol, and the bacteriostatic and bactericidal effects against Streptococcus mutans were determined. Growth of S. mutans was strongly inhibited by contact with the surface of cured MDPB/MDP-containing resin, although the bactericidal effect was small. Cured MDPB/MDP-containing resin also showed an inhibitory effect against in vitro plaque formation on its surface by S. mutans. The bactericide immobilized in Bis-GMA-based resin demonstrated bacteriostatic activity as a contact antimicrobial even when adhesion-promoting phosphoric monomer was incorporated into the materials.

Antibacterial activity of dentine primer containing MDPB after curing

OBJECTIVES

A monomer methacryloyloxydodecylpyridinium bromide (MDPB) has antibacterial activity before polymerization. Furthermore, the antibacterial agent is immobilized by the polymerization of MDPB and the resin-based material incorporating MDPB is able to show an antibacterial effect even after being cured. The purpose of this study was to investigate the antibacterial effect of a dentine primer containing MDPB after curing.

METHODS

The inhibitory effect of a cured MDPB-containing primer on the growth of Streptococcus mutans, Actinomyces viscosus and Lactobacillus casei was determined by the agar-disc method. The bactericidal activity of cured primer during a 1-h contact period was assessed using S. mutans, and the elution of unpolymerized MDPB was measured with high performance liquid chromatography.

RESULTS

Cured MDPB-containing primer showed an inhibitory effect on the growth of all species which were in contact with the specimen surface, and displayed a little bactericidal effect on S. mutans without releasing any unpolymerized antibacterial components.

CONCLUSION

Incorporation of antibacterial monomer MDPB into dentine primer is beneficial for providing antibacterial activity after curing.

Weight change of various light-cured restorative materials after water immersion

This study investigated weight changes of various light-cured glass-ionomer cements and other restorative materials during water immersion and compared findings with those of conventional glass-ionomer cement and light-cured resin composites. Three light-cured glass-ionomer cements, two polyacid-modified composite resins, one conventional glass-ionomer cement, and one light-cured composite resin were evaluated in this study. The weight changes of these specimens after water immersion were measured using an electronic analytical balance and adjusted according to water solubility measured at the same time weight change was measured. The results were analyzed by one-way ANOVA and Scheffé's F test at P < 0.05. The weight change of Photac-Fil Aplicap was the largest, and there were significant differences among the materials (P < 0.05). Weight change after 6 weeks' water immersion was noted in the following order: Fuji Ionomer Type II LC, Vitremer, Fuji Ionomer Type II, VariGlass VLC, Geristore V, and Clearfil AP-X. It is suggested that the amount of water sorption of light-cured glass-ionomer cements is greater than that of polyacid-modified composite resins.

Photoelastic analysis of polymerization contraction stresses in resin composite restorations

OBJECTIVES

The objective of this study was to determine the distribution and the magnitude of the internal stresses in a resin composite restoration resulting from polymerization shrinkage by using photoelastic analysis.

METHODS

Butt-joint box-shaped cavities (5.0 x 2.0 mm, 2.0 mm in depth) prepared in bovine teeth and in composite moulds were filled with the light-activated transparent composite. The restoration was cross-sectioned perpendicularly to the longitudinal side of the cavity and observed with polarized microscopes. The principal stresses of the restoration, normal and shear stresses at the cavity wall were evaluated by the graphical integration method. The integrity of the bond along the cavity wall was also examined by staining method.

RESULTS

The internal stresses of the restorations in bovine teeth were not large enough to observe, apparently because the gaps along the dentinal wall acted as a stress relief. On the other hand, there were no gaps along the cavity walls at the restorations in the composite moulds. As flow of the resin composite was severely limited, the maximum normal tensile stress at the cavity wall, which occurred near the internal line angle of the cavity, was calculated to reach as high as 23 MPa. The stress level near the internal line angle was higher than that near the cavo-surface margin.

CONCLUSION

The distribution of the internal stresses in a composite restoration in a box-shaped cavity is considered to be unfavorable for the deep dentin bond. A good understanding of these phenomena may improve the clinical effectiveness of resin composite restoration.

Differential effects of beta-endorphin and Met- and Leu-enkephalin on steroid hormone-induced lordosis in ovariectomized female rats

The effect of intrathirdventricular (I.T.V.) injections of beta-endorphin, anti-beta-endorphin antiserum, Met-enkephalin, Leu-enkephalin, and naloxone on the initial activation and final development of steroid hormone-mediated induction of female sexual receptivity was studied in ovariectomized female rats. The lordosis response to male mounts in ovariectomized rats after subcutaneous (S.C.) estradiol benzoate (EB) and progesterone (Prog) priming was facilitated by beta-endorphin, and Met-enkephalin (10 microg x 5 microl(-1)), but inhibited by Leu-enkephalin, when the peptides were injected into the third ventricle at the time of S.C. EB priming. A lower dose Met-enkephalin had no effects. Lordosis behavior in steroid hormone-primed rats was significantly facilitated when I.T.V. injections of Met-enkephalin were given 1 h prior to behavioral testing (47 h after EB priming). At 1 h prior to behavioral testing (47 h after EB priming), I.T.V. injection of beta-endorphin significantly inhibited lordosis behavior, especially at the higher dose of beta-endorphin (10 microg x 5 microl(-1)). Under those conditions, Leu-enkephalin had no effect. Lordosis behavior of ovariectomized female rats receiving S.C. steroid hormones and I.T.V. injection of anti-beta-endorphin antiserum was significantly inhibited when anti-beta-endorphin antiserum was injected at the time of EB priming. However, lordosis was significantly facilitated when anti-beta-endorphin antiserum was injected 1 h prior to the behavior testing (47 h after EB priming). In contrast, I.T.V. injection of the opioid antagonist naloxone given either at the time of EB priming or 1 h prior to behavioral testing (47 h after EB priming) decreased lordosis behavior. The present results suggest that 1) beta-endorphin, Met-enkephalin, and Leu-enkephalin have differential effects in the control of lordosis behavior; 2) the opioidergic systems may modulate initial-stage and final-stage estrogen-induced lordosis behavior; and 3) the opioidergic systems could be divided into the endorphinergic modulation-type and enkephalinergic modulation-type, based on their effects on lordosis behavior.

Two antigens on zygotes and ookinetes of Plasmodium yoelii and Plasmodium berghei that are distinct targets of transmission-blocking immunity

We have developed transmission-blocking monoclonal antibodies (MAbs) against Plasmodium yoelii 21-kDa (Pys21) and 28-kDa (Pys25) ookinete surface proteins. These MAbs block infectivity of P. yoelii to Anopheles stephensi. One MAb, 14, cross-reacted by Western blotting with a 28-kDa surface protein (Pbs25) of P. berghei ookinetes and blocked oocyst development, as assayed by direct mosquito feeds on passively immunized P. berghei-infected mice. In total, we have identified two ookinete surface proteins in P. yoelii, one of which is also present in P. berghei. The transmission-blocking activity of the anti-Pys25 MAb 4 was complete and more potent than that of the anti-Pys21 MAb 2. Moreover, Fab fragments of MAb 4 had transmission-blocking activity in mice. In comparison, Fab fragments of MAb 2 did not have detectable transmission-blocking effect, although F(ab')2 did. Furthermore, MAb 2 and MAb 4 appeared to block the in vitro formation and development of zygotes as well.

Incorporation of antibacterial monomer MDPB into dentin primer

The polymerizable monomer methacryloyloxydodecylpyridinium bromide (MDPB) shows antibacterial activity when immobilized in a resin-based material. In this study, the antibacterial effect of a dentin primer incorporating MDPB was investigated. The influence of incorporation of MDPB on bond strength to dentin and on the curing performance of the adhesive system was also evaluated. Experimental primers were prepared by addition of MDPB into a proprietary primer at 1, 2, or 5%. Antibacterial effects of experimental primers were compared with those of control primer and two other proprietary primers by an agar disc-diffusion method and bactericidal activity test. Experimental primers produced greater inhibition zones against Streptococcus mutans, Actinomyces viscosus, and Lactobacillus casei than any of three proprietary primers, and inhibition increased as the concentration of MDPB was increased. Bactericidal activity of MDPB-containing primers against Streptococcus mutans was greater than those of the other three primers, with incorporation of MDPB at 5% showing complete killing of bacteria after 30 s contact. No decrease in tensile bond strength was observed for materials containing MDPB. On the contrary, the primer incorporating 1 and 2% MDPB showed higher bond strength than all the others, including the control (p < 0.05). When the degree of conversion of the complex of primer and adhesive resin was determined with Fourier Transform Infrared Spectroscopy, there were no significant differences between any of the experimental primers and the control (p > 0.05). These results indicate that incorporation of the antibacterial monomer MDPB enhanced the antibacterial effect of a proprietary dentin primer before curing, and had no adverse influence on bond strength to dentin and curing of the adhesive system.

Membrane knobs of unfixed Plasmodium falciparum infected erythrocytes: new findings as revealed by atomic force microscopy and surface potential spectroscopy

Cerebral malaria, a severe complication of malaria, is caused by the obstruction of cerebral microvessels by Plasmodium falciparum-infected erythrocytes. Such cells adhere to endothelial cells by means of "knobs" induced on the red cell membrane by the parasites. When atomic force microscopy was used to investigate the structure of the knobs of unfixed infected red cells, each knob was found to consist of two distinct subunits, knob components that have never been seen in chemically fixed knobs examined by conventional transmission electron microscopy. Surface potential spectroscopy revealed that the knobs have a positive charge (+20 mV), whereas the remainder of the red cell plasma membrane is negatively charged. Since endothelial plasma membranes have a negative charge, the charge difference between knobs and endothelium may play a significant role in cytoadherence between the two cell types. The subunit structure of the knobs may be a steric necessity to align adherence molecules so that they can exert their effect. This study shows that the atomic force microscope has great potential for examination of cells in their native state; in combination with surface potential spectroscopy, it may uncover fundamental processes and mechanisms in cell function.

Cerebral cysticercosis manifesting as hydrocephalus--case report

A 70-year-old female presented with gait disturbance and dementia. Cerebrospinal fluid examination revealed mild aseptic meningitis. Magnetic resonance images showed multiple cystic lesions and mural nodules in some of the cysts in the cerebral parenchyma. Metrizamide computed tomography clearly demonstrated multiple intracisternal cysts. Some cysts were surgically excised and a ventriculoperitoneal shunt was implaced. Postoperatively, her gait disturbance and dementia disappeared. Histological examination revealed cysticercosis with viable larva. Ten months after the initial surgery, she presented with right hemiparesis due to enlargement of the remaining cysts in the left frontal lobe. These cysts were removed. Postoperative neurological examination showed slight right hemiparesis. We recommend ventriculoperitoneal shunting for hydrocephalus due to cisternal cysticercosis and praziquantel administration for parenchymal lesions.

Roles of cell-autonomous mechanisms for differential expression of region-specific transcription factors in neuroepithelial cells

Although a number of genes have been found to have restricted expression domains in the embryonic forebrain and midbrain, it remains largely unknown how the expression of these genes is regulated at the cellular level. In this study, we explored the mechanisms for the differential expression of region-specific transcription factors in neuroepithelial cells by using both primary and immortalized neuroepithelial cells from the rat brain at embryonic day 11.5. We found that differential expression patterns of Pax-3, Pax-5, Pax-6, Dlx-1, Dlx-2, Emx2, Otx1 and Dbx observed in vivo were maintained even when the cells were isolated and cultured in vitro, free from environmental influences. Furthermore, in response to Sonic hedgehog, which is a major inductive signal from the environment for regional specification, neuroepithelial cells that maintain distinct regional identities expressed different sets of ventral-specific genes including Islet-1, Nkx-2.1 and Nkx-2.2. These results suggest that certain cell-autonomous mechanisms play important roles in regulating both environmental signal-dependent and -independent expression of region-specific genes. Thus, we propose that use of the in vitro culture systems we describe in this study facilitates the understanding of regulatory mechanisms of region-specific genes in neuroepithelial cells.

Influence of opioid peptides on the priming action of estrogen on lordosis in ovariectomized rats

Lordosis in response to male mounting in estrogen-progesterone primed ovariectomized rats was facilitated by beta-endorphin or metenkephalin but inhibited by leu-enkephalin if the peptides were injected into third ventricle at the time of estrogen-priming. It is suggested that opioidergic systems modulate the activation of the estrogen-dependent brain functions that control lordosis.

Effect of prewarming in the cold season on thermoregulatory responses during exercise

OBJECTIVE

To assess whether thermoregulation in the cold season can be affected by prewarming before exercise.

METHODS

Four healthy non-athletic unacclimatised males were exercised to the same degree in summer and winter on a bicycle ergometer without prewarming (experiment 1) and after prewarming by sitting for 30 min in a room at 30 degrees C (experiment 2). During exercise, sweat production and rectal and skin temperatures were measured continuously.

RESULTS

There was seasonal variation in sweating capacity and sensitivity and in heat storage during exercise without prewarming (experiment 1). After the subjects were warmed before exercise, there was no such seasonal variation in their sweat rates during exercise at 30 degrees C and 40 degrees C (experiment 2). In both cases, the sweat rate and skin temperature were dependent on the environmental temperature, and the sweat rate and core temperature were dependent on the workload. In the cold season, sweating sensitivity and evaporative cooling response could be enhanced by thermal stimulation. There was no seasonal difference in the relation between evaporative heat loss and metabolic rate in the two thermal conditions. These values did not differ significantly between winter after prewarming and summer (P > 0.05), neither did heat storage and metabolic heat production at various workloads (P > 0.05).

CONCLUSIONS

There is adaptation of the thermoregulatory mechanisms during temperature acclimatisation. Body warming enhances not only the heat dissipating activity of the thermoregulatory centre but also the induction of peripheral sweat gland activity. Seasonal change of sweat rate in exercising men can be eliminated through a different type of acclimatisation by prewarming in the cold season.

Antibacterial effect of composite incorporating Triclosan against Streptococcus mutans

It has been shown that composite incorporating the antibacterial agent Triclosan (Irgasan DP 300, which is sparingly soluble in water, inhibited in vitro plaque formation by Streptococcus mutans, although the release of the agent was much less than the minimum inhibitory concentration for the bacterium. In this study, the inhibitory effect of the composite incorporating 1% Triclosan against growth and adherence of S. mutans was investigated. S. mutans was inoculated on the surface of a specimen made of control or Triclosan-incorporated composite and the number of bacteria was compared after 3, 6, 12 and 24 hr of incubation. The adherence of S. mutans to the control and experimental composite, with or without saliva treatment, was also examined by scanning electron microscopy. The composite incorporating Triclosan demonstrated significant inhibition of growth of S. mutans after 6, 12 and 24 hr of incubation. Adherence of S. mutans to the Triclosan-incorporated composite was less compared with control for both non-treated and saliva-treated specimens. It is concluded that the antiplaque effect of composite incorporating Triclosan depends upon its ability to inhibit bacterial growth and adherence, and Triclosan-incorporated composite is able to exhibit the antibacterial activity even after being treated with saliva.

Maximal sweating rate in humans

We reviewed the literature concerning the maximal sweating rate (SRmax) during heat acclimatization, walking in desert heat and marathon running, and analyzed it from the viewpoint of sex, age, level of maximal oxygen uptake, and experimental conditions, i.e., ambient temperature, relative humidity, work intensity, work type, working duration, seasonal factors and the techniques of heat acclimatization. Exercise simulation, walking, running or bicycling, to induce the SRmax was conducted in a hot climatic chamber or in the desert. The SRmaxs due to marathon running were 1,000 to 1,200 g.h-1 in the cold season and 1,500 to 2,000 g.h-1 in the hot season. After several days of heat acclimatization, sweating capacity in the exercise simulation reached a maximum rate, over 2,000 g.h-1. There was a sexual difference in the SRmax, and the sweating capacity in the female was less than that in the male. Thus, the maximal sweating capacity in human was observed by prolonged moderate muscular exercise under thermal stress and internal and/or external heat loads.

Additional heat-curing of light-cured composite resin for inlay restoration

The purpose of this study was to evaluate the effect of heat application after light curing on some physical properties of composite resin for dental inlay. Specimens each were additionally dry heat-cured at various temperatures for 15 min after initial light curing, and other specimens were not heat-cured as a control. Fracture toughness, bending strength, bending elastic modulus, coefficient of thermal expansion, hygroscopic expansion, microhardness, water absorption and solubility were determined. Fracture toughness, bending strength and bending elastic modulus were significantly higher when heated at 80-120 degrees C than the control. The coefficient of thermal expansion, hygroscopic expansion, microhardness and solubility were significantly improved than those of the control when heated, while water absorption was not significantly altered by dry heat-curing. These results indicate that the physical properties of composite resin, except water absorption, were improved significantly when heated after initial cure.

Adhesion of Plasmodium falciparum-infected erythrocytes to human cells and secretion of cytokines (IL-1-beta, IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, GM-CSF

The scientific interest in the physical interaction of Plasmodium falciparum-infected erythrocytes with host cells stems from the suggestion that excessive binding in the microvasculature leads to severe malaria. The authors studied, therefore, two parasites for their ability to adhere to normal human cells and to induce cytokine production, one parasite lacking a binding capacity (DD2) and one which adhered to CD36+ transfected CHO cells (MCAMP). The MCAMP parasites readily bound to platelets and erythrocytes and to monocytes, polymorphonuclear granulocytes and EBV-transformed B cells as seen by light and electron microscopy. Platelets were frequently attached in large numbers to the infected erythrocyte surface and groups of infected erythrocytes were sometimes held together by several platelets. Nine out of 17 cytokines tested were found to be secreted into the culture supernatants after 35 h of co-cultures containing monocytes or unfractionated peripheral blood mononuclear cells (PBMC) and parasites (IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, IL-1-beta, and GM-CSF). Three additional cytokines were also present in low levels (< 200 pg/ml, IL-2, IL-4, IFN gamma) in the culture supernatants after incubation of the cells for 4 days. TNF alpha, IL-RA, and IL-8 were secreted from polymorphonuclear granulocytes, LGLs and T cells. Platelets and, to a lesser degree, monocytes and T cells secreted large amounts of TGF beta (10-30 ng/ml). Cytokines may participate in the pathogenesis but also the suppression of immune responses seen during acute malarial infections.

Comparative study on free radical injury in the endothelium of SHR and WKY aorta

1. Using 13 week old SHR and WKY rats, aortic endothelial injury was examined after tert-butylhydroperoxide (t-BOOH) perfusion. 2. ESR analysis revealed a hydroxyl radical adducts in the perfusate after t-BOOH perfusion. 3. After t-BOOH perfusion, endothelial changes such as cauliflower-like blebs and crater-like holes were frequently observed in the SHR aorta, but rarely seen in the WKY aorta. 4. X-ray spectra revealed the cerium perhydroxide deposition on the surface of endothelial cells of the SHR aorta. 5. These findings indicate that free radical injury is much more intense in the endothelial cells of SHR than in those in WKY.

Marginal adaptability and fit of ceramic milled inlays

The authors investigated the marginal adaptation and internal fit of ceramic inlay made by a ceramic milling system. The study's results indicated that the mean marginal and internal gap size of the ceramic inlay restorations was less than 100 microns, making the fit clinically acceptable.

Murine complement reduces infectivity of Plasmodium yoelii to mosquitoes

The alternative pathway of complement in the mouse serum significantly reduced, but did not eliminate, the infectivity of Plasmodium yoelii to Anopheles stephensi. The reduction of the infectivity is mainly due to the inability of the zygote to transform into the ookinete in the mosquito midgut.

Naloxone and initial estrogen action to induce lordosis in ovariectomized rats: the effect of a cut between the septum and preoptic area

The effects of intra-third-ventricular (ITV) injection of naloxone (NLX), an opioid receptor antagonist, on lordosis behavior were studied in ovariectomized female rats given a horizontal half-circle cut located just above the anterior commissure (ARD) and subcutaneously (s.c.) treated with estradiol benzoate (EB) and progesterone (Prog). In ARD-sham control animals, lordosis quotient (LQ) was 78.8 +/- 4.2% (SE,n = 8). LQ (48.3 +/- 7.2%, SE, n = 8) in the ARD-sham rats significantly decreased with the ITV injection of NLX at the time of s.c. EB-priming. In contrast, lordosis reflex in the ARD-operated animals was maximally facilitated (sham versus ARD, P < 0.01). LQ in the ARD-operated rats did not decrease with the ITV injection of NLX at the s.c. EB-priming. The present results suggest that the opioidergic systems modulate an initial phase of estrogen action to induce lordosis and play a part in neural input from the forebrain structures to regulate female sexual receptivity.