The spatial distribution of enteric bacteria in the Jordan River-Lake Kinneret contact zone

Lake Kinneret, in the north of Israel, is the only freshwater body in the country. It supports many activities, including recreation, tourism, and a commercial fishing industry, but its prime function is to supply water to other parts of the country. Consequently, maintaining a high water quality of the lake is of prime importance. The major part (some 90%) of the annual runoff of water enters Lake Kinneret from the north via the Jordan River during the autumn-winter floods. During this period, the river carries sediments, toxic agricultural chemicals, and allochthonous organisms, including pathogenic bacteria, into the lake. The Jordan River-Lake Kinneret contact zone is characterized by a rapid transformation from a riverine to a lacustrine water mass within 700 m from the river mouth, with very high spatial gradients of practically all hydrodynamic, hydrophysical, hydrochemical, and microbiological parameters. Previous measurements have shown that the distribution of enteric bacteria in the river-lake contact zone is related to the attenuation of river current flows. The aim of this study was to determine whether the change in the number of enteric bacteria (fecal coliforms, Escherichia coli, and Klebsiella spp.) in the water of the River Jordan-Lake Kinneret contact zone was due to sedimentation or to dilution. The data were then utilized to build a conceptual model explaining the distribution of biological pollutants (bacteria) in the river-lake contact zone of a shallow tropical lake, using the microbial communities of the River Jordan-Lake Kinneret contact zone, as an example.     

Is herpes simplex virus associated with pulp/periapical inflammation?

OBJECTIVES: This study focuses on the detection of herpes simplex virus (HSV) DNA in dental pulp and inflamed periapical tissue.Study Design: Dental pulp tissue (vital and necrotic) and periapical tissue samples were collected under strictly sterile conditions and examined for the presence of HSV DNA. Saliva samples were also examined for the presence of the viral DNA. The polymerase chain reaction assay was used to detect viral DNA. Blood samples were collected, and the enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies against HSV was carried out. RESULTS: According to the ELISA test, 19 of the 23 blood samples were IgG-positive and IgM-negative to HSV, whereas 4 were IgG-negative and IgM-negative. HSV DNA was not detected in the tissue and the saliva samples tested. CONCLUSION: HSV is not present and therefore is probably not involved in the pathology of tooth neural tissue.     

Apoptotic promoters and inhibitors in Alzheimer's disease: Who wins out?

A spectrum of apoptotic mediators are seen in neurons that are vulnerable in Alzheimer's disease (AD), leading many investigators to suggest that neuronal death in AD is mediated by an apoptotic process. Indeed, the environment of the AD brain is awash with proapoptotic mediators including amyloid-beta, oxidative stress, hydroxynonenal oxidants and metabolic alterations with concomitant energy failures. However, the phenotype that defines the terminal events that are pathogonomic of apoptosis, such as chromatin condensation, apoptotic bodies and membrane blebbing, are not seen in AD. Therefore, we speculated that, although AD presents with a proapoptotic environment, apoptosis does not proceed to completion. In this regard, we found that while the initiator phases of apoptosis were engaged, this does not lead to the activation of the terminal commitment phase necessary for apoptotic cell death. In other words, in AD, there is a lack of effective apoptotic signal propagation to distal effectors. This is a novel phenomenon (which we term abortosis) that represents an inhibition of apoptosis at the postinitiator stage in neurons that survive in AD.     

Histologic response to intraligament injections using a computerized local anesthetic delivery system. A pilot study in mini-swine

BACKGROUND: Intraligamentary (periodontal ligament) injection has been used to locally control pain with minimal anesthetic dose. The purpose of the present study was to determine the histologic effect of using a computer-controlled local anesthesia delivery system (CCLADS) for the administration of a periodontal ligament injection in the mini-swine model system. METHODS: Thirty-two sites in 3 mini-swine pigs with healthy periodontium were selected. Each site was notched on the mesial-lingual line angle of the tooth to allow a reference for needle placement and provide a histologic marker. An anesthetic cartridge was used with a 30-gauge needle attached to the handpiece of the CCLADS. This provided a controlled flow rate for 2 minutes. The control sites were treated with the same needle in place for 20 seconds. The animals were sacrificed and provided observation periods of 1 hour, 1, 4, 7, 21, and 49 days. Specimens were stained with hematoxylin and eosin and trichrome. RESULTS: Twenty-four hours after injection, limited localized inflammation was present. By 7 days, the ligament appeared within normal limits. Apical migration of the junctional epithelium extended to the apical limit of the notch and was similar in test and control specimens. CONCLUSIONS: Within the limits of this study, the histologic results showed that tissue responses following intraligament injections using a CCLADS demonstrated limited inflammatory responses within the first 24 hours, which abated by 7 days postinjection. Similar migration of the junctional epithelium was seen in test and control specimens and was probably related to tooth injury rather than anesthetic injections. Further investigations are warranted using CCLADS to determine whether clinical benefits will translate in the human model system.