Mucoadhesive curcumin nanospheres: Biological activity, adhesion to stomach mucosa and release of curcumin into the circulation

Although mucoadhesive drug carriers for the gastro-intestinal tract (GIT) have been reported, the mucoadhesive property and drug release characteristics have never been evaluated separately, whilst the adherence of the carriers to the surface of GIT has not been directly visualized. Here, a monopolymeric carrier made from ethylcellulose (EC) and a dipolymeric carrier made from a blend of methylcellulose (MC) and EC (ECMC) were easily fabricated through a self-assembling process and yielded the highest reported curcumin loading of ~ 48-49%. Both curcumin loaded ECMC (C-ECMC) and curcumin loaded EC (C-EC) particles showed an in vitro free radical scavenging activity and a dose-dependent in vitro cytotoxic effect towards MCF-7 human breast adenocarcinoma and HepG2 hepatoblastoma cells in tissue culture. The in vivo evaluation of their adherence to stomach mucosa and their ability to release curcumin into the circulation were carried out through quantification of curcumin levels in the stomach tissue and in blood of mice orally administered with the two spheres. Direct evidence of the adherence of the C-EC and C-ECMC particles along the mucosal epithelia of the stomach is also presented for the first time through SEM images. The mucoadhesive property of self-assembled C-EC nanoparticles is discussed.     

Effect of acemannan,an extracted polysaccharide from Aloe vera,on BMSCs proliferation,differentiation, extracellular matrix synthesis,mineralization, and bone formation in a tooth extraction model

Aloe vera is a traditional wound healing medicine. We hypothesized acemannan, a polysaccharide extracted from Aloe vera gel, could affect bone formation. Primary rat bone marrow stromal cells (BMSCs) were treated with various concentrations of acemannan. New DNA synthesis, VEGF, BMP-2, alkaline phosphatase activity, bone sialoprotein, osteopontin expression, and mineralization were determined by [³H] thymidine incorporation assay, ELISA, biochemical assay, western blotting, and Alizarin Red staining, respectively. In an animal study, mandibular right incisors of male Sprague–Dawley rats were extracted and an acemannan treated sponge was placed in the socket. After 1, 2, and 4 weeks, the mandibles were dissected. Bone formation was evaluated by dual-energy X-ray absorptiometry and histopathological examination. The in vitro results revealed acemannan significantly increased BMSC proliferation, VEGF, BMP-2, alkaline phosphatase activity, bone sialoprotein and osteopontin expression, and mineralization. In-vivo results showed acemannan-treated groups had higher bone mineral density and faster bone healing compared with untreated controls. A substantial ingrowth of bone trabeculae was observed in acemannan-treated groups. These data suggest acemannan could function as a bioactive molecule inducing bone formation by stimulating BMSCs proliferation, differentiation into osteoblasts, and extracellular matrix synthesis. Acemannan could be a candidate natural biomaterial for bone regeneration.     

Apoptosis in the aged dog brain

Apoptosis similar to that seen in Alzheimer’s disease patients was found in the brain of aged dogs by the TUNEL method of detecting in situ DNA fragmentation. Apoptosis was observed in both neurons and glial cells, and was morphologically characterized by round and swollen cytoplasm and aggregated nuclear chromatin, although these changes were slight. Neurons and astrocytes in the gray matter and oligodendrocytes in the white matter were affected. The number of ApopTag-positive brain cells increased slightly with age, but was not correlated to the number of senile plaques. A good correlation between the number of ApopTag-positive cells and the dementia index was clearly found. The present study indicates that brain cell apoptosis could account for dementia in aged dogs and suggested that aged dogs may be useful as a simplified animal model for Alzheimer’s disease in man. Received: 25 January 1996 / Revised, accepted: 15 March 1996     

Immunohistochemical detection of tau protein in various non-human animal brains

In order to clarify the tau phosphorylation in aged non-human animal brains, paraffin sections of human and non-human animal brains were examined immunohistochemically using two antibodies against tau. The monoclonal antibody (mAb) tau-2 is known to bind non-phosphorylated and phosphorylated forms of tau protein and to recognize neurofibrillary tangles (NFT) in the human brain, whereas rabbit antiserum against tau recognizes the protein in a wide variety of mammalian species. In this study, both antibodies recognized axons, neurites, and cytoplasm of neuronal cells together with oligodendrocytes in non-human animal brains as reported in human brains, suggesting that the distribution of normal tau is quite similar between human and non-human animal brains. Neurofibrillary tangles detected by the Gallyas method were not found in non-human animal brains. Tau-2 intensely labeled NFT in the human brain and neurons of brain stem nuclei in the canine brain. The results may suggest very early stage of abnormal tau phosphorylation leading to NFT formation in the aged canine brain. It is probable that phosphorylation develops over a long period of time (more than 25–30 years) and as a result abnormal tau becomes apparent in humans because they have a long life-span in comparison with most non-human animals.     

Senile plaques in very aged cats

Senile plaques were found in the cerebral cortices of three very aged cats (more than 18 years old). The plaques consisted of a coarse assembly of silver staining-positive materials, and was morphologically different from the well-known classical, primitive, and diffuse plaques. Congophilic amyloid angiopathy was observed in a few cortical arterioles of the oldest cat (20 years old). The senile plaques and a few cortical blood vessels were immunopositive for amyloid β-protein (Aβ). Aβ-positive materials were also sparsely distributed in the cortical neuropil but did not form senile plaques there. These findings should help to clarify the development of senile plaques and the early stage of Aβ deposition. Received: 29 May 1995 / Revised, accepted: 28 September 1995     

Antimicrobial susceptibility patterns and phage types of Salmonella typhi from Vietnam

A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salmonella typhi strains isolated in 1996 from Vietnam was carried out. The strains were tested for susceptibility to chloramphenicol, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, nalidixic acid, ceftazidime, ceftriaxone and ciprofloxacin. Simultaneous resistance to chloramphenicol, ampicillin, tetracycline and trimethoprim-sulfamethoxazole were present in 84 strains (75.7%). Nalidixic acid resistance was only observed in 2 multidrug-resistant strains (1.8%). Twenty-one strains (18.9%) were completely susceptible to all drugs tested. All 111 strains were susceptible to ceftazidime, ceftriaxone and cipropfloxacin. The MIC values for chloramphenicol, ampicillin and trimethoprim-sulfamethoxazole corresponded with the results by disk diffusion method. On Vi phage-typing, 5 different phage types (28, A, D1, E1 and M1) were found in 12 strains (10.8%). However, most S. typhi strains were indistinguishable by this typing technique because they were degraded Vi-positive or untypeable Vi-positive strains (35.1% and 54.1%, respectively). There were no correlations between antimicrobial resistance patterns and phage types in the tested S. typhi strains in this study.     

Clinical,radiographic, and histologic analysis of the effects of acemannan used in direct pulp capping of human primary teeth: short-term outcomes

Acemannan has been previously reported as a direct pulp-capping agent in animal study. This natural material demonstrated its biocompatibility and enhanced reparative dentin formation. The objective of this study was to investigate the action of acemannan as a direct pulp-capping material in human primary teeth with deep caries. Forty-two deeply carious mandibular primary molars from 37 children, aged 7–11 years old diagnosed with reversible pulpitis were studied. After completely removing the infected dentine, teeth with a pinpoint pulpal exposure were randomly divided into two treatment groups: acemannan or calcium hydroxide. A glass-ionomer cement base was applied to all teeth prior to restoration with stainless steel crowns. Clinical and radiographic evaluation was performed 6 months post-treatment. The teeth due to exfoliate were extracted and histopathologically evaluated for inflammation, dentine bridge formation, and soft tissue organization. At 6 months, the overall clinical and radiographic success rates of direct pulp capping with acemannan and calcium hydroxide at 6 months were 72.73 and 70.0 %, respectively. The histopathological results indicated that the acemannan-treated group had significantly better histopathological responses compared with the calcium hydroxide-treated group (p < 0.05). These data suggest acemannan offers a valuable alternative biomaterial for vital pulp therapy in primary teeth.     

Immunohistochemical detection of anti-oxidative stress enzymes in the dog brain

Anti-oxidative stress enzymes were immunohistochemically detected in the brain from young to very-aged dogs. More than half of the neurons in the cerebral cortex of the young dogs (< 5 years old) were positive for copper (Cu), zinc (Zn) superoxide dismutase (SOD), and the staining intensity was strong. The number of Cu, Zn SOD-positive neurons decreased with age, and only 10–50% of neurons were positive for SOD in the aged and very aged (> 9 years old) dogs. In contrast, no glial cells were immunostained for Cu, Zn SOD in the young dogs, and the number, as well as the staining intensity, increased with age, reaching > 50% in the aged and very aged dogs. Apoptotic brain cells, which were conspicuous in the aged dog brain, were negative for Cu, Zn SOD. The Cu, Zn SOD immunoreactions were also observed in the degenerative neurites of amyloid type senile plaques, vessels affected with cerebral amyloid angiopathy (CAA) and reactive astroglia around these amyloid plaques and CAA in the aged and very aged dog brains. Diffuse type senile plaques were negative for Cu, Zn SOD. The number of catalase- or glutathione peroxidase-positive cells varied among dogs regardless of their age. An age-related decrease in number of Cu, Zn SOD-positive neurons may enhance the toxicity of oxygen free radicals, resulting in neuronal cell death.     

Nivalenol-induced apoptosis in thymus, spleen and Peyer''s patches of mice

ICR:CD-1 male mice were orally administered with Nivalenol(NIV) at the dose levels of 5, 10 and 15 mg/kg body weight, and examined at 12, 24 and 48 hours after inoculation (HAI), respectively, to elucidate the process of development of apoptosis in the thymus, spleen and Peyer's patch. There were no signs of clinical disorders and no changes in body and organ weights until 48 HAI except for that the thymus weight significantly decreased at 48 HAI. Immunohistochemically, the number of apoptotic lymphocytes evaluated by in situ detection for fragmented DNA showed a dose-dependent increase at 12 HAI in both the thymus and the Peyer's patch, while it became to increase at 24 HAI in the spleen. Dead lymphocytes in the thymus, spleen and Peyer's patch showed ultrastructural characteristics of apoptosis. Moreover, the DNA ladder was first detected by agarose gel electrophoresis at 12 HAI in the thymus of 15 mg/kg-group. The results clearly indicate that NIV is able to induce apoptosis in the lymphoid tissues of mice.