The honey bee gut microbiota: strategies for study and characterization

Gut microbiota research is an emerging field that improves our understanding of the ecological and functional dynamics of gut environments. The honey bee gut microbiota is a highly rewarding community to study, as honey bees are critical pollinators of many crops for human consumption and produce valuable commodities such as honey and wax. Most significantly, unique characteristics of the Apis mellifera gut habitat make it a valuable model system. This review discusses methods and pipelines used in the study of the gut microbiota of Ap. mellifera and closely related species for four main purposes: identifying microbiota taxonomy, characterizing microbiota genomes (microbiome), characterizing microbiota-microbiota interactions and identifying functions of the microbial community in the gut. The purpose of this contribution is to increase understanding of honey bee gut microbiota, to facilitate bee microbiota and microbiome research in general and to aid design of future experiments in this growing field.

Novel biosensors for quantitative phytic acid and phytase measurement

Phytase (EC 3.1.3.26) and phytic acid (myo-inositol hexaphosphate) play an important environmental role in poultry industry and have a health aspect in food industry. Novel biosensors have been developed for simple, one step quantitative phytic acid and phytase detection. A system based on the sequentially acting enzyme phytase and pyruvate oxidase (POD) was employed for the development of phytase and phytic acid biosensors. Poly(carbamoylsulphonate) (PCS) hydrogel immobilized POD electrode was applied for the detection of phytase. It was based on the indication of phosphate ions produced by the hydrolysis of phytic acid. The phytase biosensor showed a linear response ranging from 0.5 to 6.0 units/ml. A bi-enzyme sensor based on co-immobilization of phytase and POD was developed for the detection of phytic acid on the basis of amperometric detection of the enzymatically-generated hydrogen peroxide at 0.6 V versus Ag/AgCl. It showed a linear response ranging from 0.2 to 2.0 mM with a detection limit of 0.002 mM.

Microsatellite instability and mutation of DNA mismatch repair genes in gliomas

Microsatellite instability (MSI) has been identified in various human cancers, particularly those associated with the hereditary nonpolyposis colorectal cancer syndrome. Although gliomas have been reported in a few hereditary nonpolyposis colorectal cancer syndrome kindred, data on the incidence of MSI in gliomas are conflicting, and the nature of the mismatch repair (MMR) defect is not known. We established the incidence of MSI and the underlying MMR gene mutation in 22 patients ages 45 years or less with sporadic high-grade gliomas (17 glioblastomas, 3 anaplastic astrocytomas, and 2 mixed gliomas, grade III). Using five microsatellite loci, four patients (18%) had high level MSI, with at least 40% unstable loci. Germline MMR gene mutation was detected in all four patients, with inactivation of the second allele of the corresponding MMR gene or loss of protein expression in the tumor tissue. Frameshift mutation in the mononucleotide tract of insulin-like growth factor type II receptor was found in one high-level MSI glioma, but none was found in the transforming growth factor beta type II receptor and the Bax genes. There was no family history of cancer in three of the patients, and although one patient did have a family history of colorectal carcinoma, the case did not satisfy the Amsterdam criteria for hereditary nonpolyposis colorectal cancer syndrome. Three patients developed metachronous colorectal adenocarcinomas, fitting the criteria of Turcot's syndrome. Thus, MSI and germline MMR gene mutation is present in a subset of young glioma patients, and these patients and their family members are at risk of developing other hereditary nonpolyposis colorectal cancer syndrome-related tumors, in particular colorectal carcinomas. These results have important implications in the genetic testing and management of young patients with glioma and their families.

Presence of Epstein-Barr virus in lymphoepithelioma-like carcinoma of the middle ear

AIM

To examine the association of Epstein-Barr virus (EBV) with carcinoma of the ear.

METHODS

Five non-keratinising squamous cell carcinomas and two undifferentiated carcinomas of the ear were examined. In situ hybridisation was used to localised EBV-encoded RNAs (EBER). Immunohistochemical methods to detect LMP-1 and EBNA2 were performed in the EBER positive cases.

RESULTS

Two cases were EBER positive, including one non-keratinising and one undifferentiated carcinoma. Both showed identical morphology to those arising from the nasopharynx, with abundant lymphoid stroma. They were both negative for LMP-1 and EBNA2.

CONCLUSIONS

EBV associated carcinoma with the morphology of lymphoepithelioma can also arise from the middle ear.

An Epstein-Barr virus positive undifferentiated carcinoma in the lacrimal sac

We report a Chinese patient who presented with metastatic undifferentiated carcinoma in the cervical lymph node of unknown primary origin. Despite a raised IgA titre against Epstein-Barr virus capsid antigen, examination and biopsy of the nasopharynx were negative. Radiotherapy was given to the head and neck region with the orbit shielded. There was complete resolution of the metastatic lymph nodes. She developed proptosis of her left eye one year afterward when a large tumour was found in the lacrimal sac region. Review of the initial computerized tomography revealed a small soft tissue mass in the same region. The tumour was composed of undifferentiated carcinoma cells associated with dense lymphoid infiltrate. In situ hybridization for Epstein-Barr virus EBER RNA showed strong positive signals in the malignant cells. This is the first reported case of an Epstein-Barr virus positive undifferentiated carcinoma with lymphoid stroma in the lacrimal sac. In addition to the nasopharynx, salivary glands, nasal cavity and paranasal sinuses, the lacrimal sac should be considered as a potential primary site for Epstein-Barr virus positive metastatic undifferentiated carcinoma in the cervical lymph nodes.

Epstein-Barr virus is present in a wide histological spectrum of sinonasal carcinomas

Nasopharyngeal carcinomas, a common occurrence in Southern Chinese people, shows a strong association with Epstein-Barr virus (EBV); in the same population, sinonasal carcinomas are distinctly rare. Although most nasopharyngeal carcinomas are lymphoepitheliomas, sinonasal carcinomas have a wide morphological spectrum. We studied the clinicopathological features and EBV status of 29 sinonasal carcinomas from Hong Kong Chinese patients. By in situ hybridization using antisense Epstein-Barr virus early RNA (EBER) probe, seven tumors were shown to be strongly positive for the EBV RNA. They displayed a wide morphological spectrum, including one cylindric cell carcinoma, one intestinal type adenocarcinoma, four nonkeratinizing squamous cell carcinomas, and one undifferentiated carcinoma. All were from elderly subjects (mean age, 67), including six men and one woman. Three of these seven patients had complete remission after radiotherapy with a median follow-up period of 29 months. In two cases, EBV latent membrane protein-1 was expressed. Detection of the virus in a number of histological subtypes, including cylindric cell carcinoma and adenocarcinoma, suggests that EBV may play a role in the pathogenesis of a diverse spectrum of carcinomas.

Nasopharyngeal carcinoma. Pattern of tumor regression after radiotherapy

The primary tumor regression pattern of 50 patients with nasopharyngeal carcinoma was reported. The tumor regression was monitored either by indirect nasopharyngeal mirror examination and biopsy or fiberoptic endoscope and biopsy. Fiberoptic endoscope and biopsy was found to be more accurate in noting residual tumor. It is recommended that booster radiation dose to the residual primary tumors be withheld unless positive biopsy samples persist at 10 or more weeks after radiotherapy.

Fabricating acrylic resin baseplates for complete dentures

A technique for fabricating acrylic resin baseplates for complete dentures has been described. With this technique multiple sets of baseplates can be made at a time for a set of master casts. As with all polymethyl methacrylate resins, polymerization shrinkage is present. However, by using denture repair acrylic resin, shrinkage is minimized. Furthermore, when necessary, conventional procedures can be applied to stabilize the baseplates.

Effect of exchange exocrine pancreatic insufficiency on small intestine in the mouse

A genetically conditioned mouse model of exocrine pancreatic insufficiency (epi) has been used to study the effect of the absence of lumenal proteases on small intestinal mucosal proteins. The small bowel was divided into eight equal segments. Enzyme activity was increased only in the first three segments in the case of maltase, sucrase, and lactase (all mol wt above 200,000). Alkaline phosphatase (mol wt 145,000), trehalase (mol wt 95,000), and peptidase (mol wt 175,000) activities were unaffected in proximal segments from epi mice. Proximal brush border proteins were identified and measured quantitatively by sodium dodecyl sulfate acrylamide gel electrophoresis. Those enzymes with increased activity were associated with increased amounts of protein in epi mice. Double labeled studies of protein turnover revealed a longer half-life for large brush border proteins (mol wt above 175,000) in epi mice than in normal mice. Enterokinase activity (a marker for duodenal mucosa) was nearly absent from the duodenum of epi mice. Receptors for the intrinsic factor-vitamin B12 complex (markers for ileal mucosal) were present in the ileum equally in normal and in epi mice. Enterokinase activity can be induced in epi mice by feeding its substrate trypsinogen, but not by trypsin or chymotrypsinogen. Epi mice thus retain the ability to synthesize enterokinase. Pancreatic proteases play an important role in the turnover of certain large mucosal proteins and in the induction of enterokinase.