The multidisciplinary management of hypodontia: a team approach.

Hypodontia is a frequently encountered condition within general dental practice. Its successful management involves the interplay of a number of clinicians. The general dental practitioner plays a key role in the management of patients. The aim of this short article is to outline some of the principles of the multidisciplinary management of hypodontia with an emphasis on orthodontic treatment.

Microbial contamination of laboratory constructed removable orthodontic appliances.

OBJECTIVES: This study aims to determine whether laboratory constructed removable orthodontic appliances are free from microbial contamination prior to clinical use and to evaluate the dental hospital cross-infection procedures to ensure that patient-derived contamination does not enter the construction process, thereby propagating a cycle of cross-contamination. MATERIALS AND METHODS: The construction process of removable orthodontic appliances from three individuals was evaluated at every stage, from impression to final delivery of the appliance using molecular microbiological techniques. The bacterial profiles at each stage of appliance construction were obtained using denaturing gradient gel electrophoresis, along with the bacterial profiles of the three participants' saliva. This enabled the bacterial profiles found at each stage of construction to be compared directly with the saliva of the person for whom the appliance was being constructed. Bacteria were identified at each stage using 16S rDNA PCR amplification and sequence phylogeny. RESULTS: There was no evidence of bacterial cross-contamination from patients to the laboratory. The current process of disinfection of impression appears to be adequate. Contamination was found on the final removable appliances (0.97 × 10(2)-1.52 × 10(3) cfu ml(-1)), and this contamination occurred from within the laboratory itself. CONCLUSIONS: Every effort is made to reduce potential cross-infection to patients and dental professionals. Newly constructed removable appliances were shown not to be free from contamination with bacteria prior to clinical use, but this contamination is environmental. Further studies would be required to determine the level of risk this poses to patients. CLINICAL SIGNIFICANCE: Dental professionals have a duty of care to minimise or eradicate potential risks of cross-infection to patients and other members of the team. To date, much less attention has been paid to contamination from the orthodontic laboratory, so contamination and infection risks are unknown.

Time-dependent recontamination rates of sterilised dental instruments.

OBJECTIVES: To determine time-related recontamination rates of sterilised instruments, following guidance from the UK Department of Health (HTM 01-05) that such instruments within primary dental care may only be stored for 60 days following sterilisation using a vacuum autoclave. MATERIALS AND METHODS: A total of 25 used examination mirrors underwent a washer-disinfector cycle, individual packaging and finally vacuum autoclaving. Immediately after autoclaving, time zero, five mirrors were tested for microbial contamination by aerobic and anaerobic culture. At 31, 60, 90 and 124 days a further five mirrors were removed from their packaging and were similarly tested for microbial contamination. RESULTS: There was no bacterial growth on blood-enriched media under both aerobic and anaerobic conditions after 5 days of incubation at 37°C at any time period from 0 to 124 days post-sterilisation. CONCLUSIONS: There was no recontamination of sterilised instruments in this investigation over the test period of 124 days. This exceeds the recommended limit of 60 days stated by the UK Department of Health. The new guidance, HTM 01-05, appears to place an extra burden on primary care dentists. This burden is not without associated costs, and at present does not appear to be based on published evidence.

Endovascular treatment of cranial dural arteriovenous fistulae: a single-centre, 14-year experience and the impact of Onyx on local practise.

INTRODUCTION: Dural arteriovenous fistulae (DAVFs) are a potentially dangerous group of intracranial arteriovenous shunts with significant morbidity and mortality. Treatment has traditionally included transvenous and/or transarterial embolisation, which may be followed by surgical ligation. This study assesses the impact of Onyx on treatment. METHODS: Forty-nine consecutive patients referred for endovascular management of DAVFs between 1994 and 2008 were included in a retrospective, intention-to-treat analysis. DAVFs managed conservatively or purely surgically were excluded. Success rates and complications were compared between patients treated by transvenous, transarterial Onyx and transarterial non-Onyx material embolisation. RESULTS: Fifty-six separate DAVFs were detected in 49 patients. Embolisation of 52 DAVFs was performed or attempted. Transvenous sinus occlusion of ten type I or II DAVFs resulted in cure but was unsuccessful in a single type IV fistula and three of the four indirect carotico-cavernous fistulae treated in this way. Two type I and nine type III/IV were identified in the transarterial, non-Onyx group and three of 11 (27.3%) were cured. Amongst the six type II and 20 type III/IV DAVFs belonging to the transarterial Onyx group, cure was achieved in 17 of 26 (65.4%) rising to 72.7%, considering only those cases where the fistula could be accessed and Onyx was injected. CONCLUSIONS: The introduction of Onyx has improved the endovascular cure rate of DAVFs, particularly types III and IV. Advances in technology have made an endovascular approach the management of choice for the majority of DAVFs requiring treatment. Low complication rates are achievable.

Ganglioneuroma of the mandible resulting from metastasis of neuroblastoma.

Neuroblastoma, ganglioneuroblastoma and ganglioneuroma are neuroblastic tumours derived from primordial neural crest tissue. The authors report a rare presentation of a ganglioneuroma of the mandible arising from a metastasis of an adrenal neuroblastoma. The pathogenesis and behaviour of ganglioneuromas is discussed, together with recommendations for their management.

Trans-sphenoidal encephalocele in association with Dandy-Walker complex and cardiovascular anomalies.

We present a case of trans-sphenoidal encephalomeningocele in association with a posterior cranial fossa malformation which fulfils the criteria for the Dandy-Walker complex [1]. Congenital cardiovascular defects were also present. An abnormality of neural crest development may be responsible for the combined occurrence of these anomalies.

Can spontaneous spinal epidural haematoma be managed safely without operation? A report of four cases.

The presentation, investigation, and management of four patients with spontaneous spinal epidural haematoma is presented. In each case the diagnosis was made by MRI. At the time of diagnosis spontaneous recovery had started in each patient and therefore they were all treated conservatively. In each case follow up MRI confirmed rapid reduction in the size of the haematoma and no underlying cause was demonstrated. The presentation, diagnosis, and rationale for treatment are discussed. Conservative treatment is safe in some cases of spinal epidural haematoma if early neurological recovery has started.

Generation of retroviral vector for clinical studies using transient transfection.

Transient transfection of 293T cells was utilized to produce high-titer murine recombinant retroviral vectors for clinical studies. This system was initially optimized by gene transfer using different retroviral envelope proteins into activated human CD4+ T lymphocytes in vitro. Higher titer and infectivity were obtained than with stable murine producer lines; titers of 0.3-1 x 10(7) infectious units per milliliter for vectors encoding the green fluorescent protein (GFP) were achieved. Virions pseudotyped with envelope proteins from gibbon ape leukemia virus or amphotropic murine leukemia virus resulted in gene transfer of > or = 50% in CD4+ human T lymphocytes with this marker. Gene transfer of Rev M10 with this vector conferred resistance to HIV infection compared with negative controls in the absence of drug selection. Thus, the efficiency of transduction achieved under these conditions obviated the need to include selection to detect biologic effects in T cells. Finally, a protocol for the production of large-scale supernatants using transient transfection was optimized up to titers of 1.9 x 10(7) IU/ml. These packaging cells can be used to generate high-titer virus in sufficient quantities for clinical studies and will facilitate the rapid, cost-effective generation of improved retroviral, lentiviral, or other viral vectors for human gene therapy.

Inducible expression of human hepatitis B virus (HBV) in stably transfected hepatoblastoma cells: a novel system for screening potential inhibitors of HBV replication.

We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.

Magnetic resonance imaging of intracranial cavernous angiomas: a report of 13 cases with pathological confirmation.

The magnetic resonance imaging features of 13 pathologically confirmed cavernous angiomas were retrospectively reviewed. T2-weighted images were found to be the most useful, the commonest appearance being a mixed signal intensity core with a complete peripheral rim of marked hypointensity. These appearances relate largely to various stages in the evolution of haemorrhage, although the presence of calcium and slowly flowing blood also contribute.

Activation of the prolactin receptor gene by promoter insertion in a Moloney murine leukemia virus-induced rat thymoma.

The prolactin receptor (Prlr) and growth hormone receptor (Ghr) genes and the Moloney murine leukemia virus integration-2 (Mlvi-2) locus were mapped to mouse chromosome 15 and human chromosome 5 bands p12-p14. To examine the potential relationship between Mlvi-2 and the genes encoding the growth hormone receptor and the prolactin receptor, we determined the chromosomal location of all three loci in the rat, using a panel of rat-mouse somatic cell hybrids, and in the mouse, using a panel of (C57BL/6J x Mus spretus)F1 x C57BL/6J interspecific backcross mice. These analyses revealed that Ghr, Prlr, and Mlvi-2 map to chromosome 2 in the rat and to chromosome 15 in the mouse, in close proximity with each other. Pulsed-field gel electrophoresis of rat genomic DNA showed no overlaps between the gene encoding the prolactin receptor and the remaining loci. Moreover, expression of the prolactin receptor was not affected by provirus insertion in Mlvi-2. During these studies, however, we detected one T-cell lymphoma line (2779) in which the prolactin receptor gene was activated by provirus integration. Sequence analysis of polymerase chain reaction-derived cDNA clones showed that the prolactin receptor RNA message initiates at the 5' long terminal repeat and utilizes the splice donor site 5' of the gag gene to splice the viral sequences onto exon 1 of the prolactin receptor. This message is predicted to encode the intact prolactin receptor protein product. Exposure of the T-cell lymphoma line 2779 to prolactin promoted cellular proliferation.

Specific growth stimulation by linoleic acid in hepatoma cell lines transfected with the target protein of a liver carcinogen.

The hepatic carcinogen N-2-fluorenylacetamide (2-acetylaminofluorene) was shown previously to interact specifically with its target protein, liver fatty acid binding protein (L-FABP), early during hepatocarcinogenesis in rats. In search of the significance of the interaction, rat L-FABP cDNA in the sense and antisense orientations was transfected into a subline of the rat hepatoma HTC cell line that did not express L-FABP. After the transfections, the basal doubling times of the cells were not significantly different. However, at 10(-5)-10(-7) M, linoleic acid, which is an essential fatty acid, a ligand of L-FABP, and the precursor of many eicosanoids and related lipids, stimulated the incorporation of [3H]thymidine in three randomly isolated and stably transfected cell clones that expressed L-FABP, but virtually did not stimulate the incorporation of [3H]thymidine in three L-FABP-nonexpressing clones transfected with the antisense DNA. Linoleic acid at 10(-6) M increased cell number almost 3-fold (38% vs. 14%; P less than 0.0001) and thymidine incorporation nearly 5-fold (23.2% vs. 4.9%; P less than 0.001) in the L-FABP-expressing cells compared to that in the transfected nonexpressing cells. L-FABP acted specifically and cooperatively with linoleic acid, inasmuch as all the proteins other than L-FABP in the transfected L-FABP nonexpressing cells and four other fatty acids (gamma-linolenic acid, dihomo-gamma-linolenic acid, arachidonic acid, and palmitoleic acid) were unable to effect a significant elevation or difference in the level of DNA synthesis that was attributable to the transfection. Metabolism of the linoleic acid to oxygenated derivatives was apparently necessary, since the cyclooxygenase inhibitor indomethacin partly inhibited and the antioxidant lipoxygenase inhibitors nordihydroguariaretic acid and alpha-tocopherol completely abolished the growth stimulation. The evidence supports the idea that L-FABP, the target protein of the liver carcinogen, acts specifically in concert with oxygenated metabolites of linoleic acid to modulate the growth of hepatocytes.

Association of atrophy of the medial temporal lobe with reduced blood flow in the posterior parietotemporal cortex in patients with a clinical and pathological diagnosis of Alzheimer's disease.

A combination of medial temporal lobe atrophy, shown by computed tomography, and reduced blood flow in the parietotemporal cortex, shown by single photon emission tomography, was found in 86% (44/51) of patients with a clinical diagnosis of senile dementia of the Alzheimer type (SDAT). The same combination of changes was found in four out of 10 patients with other clinical types of dementia and in two out of 18 with no evidence of cognitive deficit. Of the 12 patients who died, 10 fulfilled histopathological criteria for Alzheimer's disease, nine of them having a clinical diagnosis of SDAT, and one a clinical diagnosis of multi-infarct dementia. All 10 patients with histopathologically diagnosed Alzheimer's disease had shown a combination of hippocampal atrophy and reduced parietotemporal blood flow in life. In 10 patients (nine with SDAT) out of 12 in whom the hippocampal atrophy was more noticeable on one side of the brain than on the other the parietotemporal perfusion deficit was also asymmetrical, being greater on the side showing more hippocampal atrophy. These results suggest that the combination of atrophy of the hippocampal formation and reduced blood flow in the parietotemporal region is a feature of dementia of the Alzheimer type and that the functional change in the parietotemporal region might be related to the loss of the projection neurons in the parahippocampal gyrus that innervate this region of the neocortex.

Peripheral cerebral aneurysm associated with a glioma.

This 42-year-old man with acute subarachnoid, intraventricular and parenchymal hemorrhage from an angiographically and surgically confirmed successfully clipped, right splenial artery aneurysm, subsequently manifested a grade 3 astrocytoma at the site of the aneurysm. Intracranial aneurysms are recognized in association with metastases from cardiac myxoma and choriocarcinoma, but are rarely seen with primary brain tumors. In patients with nontraumatic peripheral aneurysms it would seem prudent to biopsy the aneurysm and/or surrounding necrotic tissue at the time of surgical clipping.

A prototype high-purity germanium detector system with fast photon-counting circuitry for medical imaging.

A data-acquisition system designed for x-ray medical imaging utilizes a segmented high-purity germanium (HPGe) detector array with 2-mm wide and 6-mm thick elements. The detectors are contained within a liquid-nitrogen cryostat designed to minimize heat losses. The 50-ns pulse-shaping time of the preamplifier electronics is selected as the shortest time constant compatible with the 50-ns charge collection time of the detector. This provides the detection system with the fastest count-rate capabilities and immunity from microphonics, with moderate energy resolution performance. A theoretical analysis of the preamplifier electronics shows that its noise performance is limited primarily by its input capacitance, and is independent of detector leakage current up to approximately 100 nA. The system experimentally demonstrates count rates exceeding 1 million counts per second per element with an energy resolution of 7 keV for the 60-keV gamma ray photon from 241Am. The results demonstrate the performance of a data acquisition system utilizing HPGe detector systems which would be suitable for dual-energy imaging as well as systems offering simultaneous x-ray transmission and radionuclide emission imaging.