Characterization of an alpha-particle irradiator for individual cell dosimetry measurements

A computer-controlled, alpha-particle irradiator is described that allows for the measurement of the number and location of alpha-particle hits to individual cell nuclei, and subsequent scoring of cell survival. Cells are grown on a track-etch material (LR 115) and images are obtained of the cells prior to irradiation. The cells are then irradiated from below by a planar, collimated Am-241 source. The exposure time is varied so that the average number of hits to cell nuclei ranges from 0 to 3. After cell survival has been scored, images of the etched material are obtained and spatially registered to the original cell images. The etched images and cellular images are superimposed allowing for the determination of the number and position of hits to individual cell nuclei. This paper characterizes the irradiator including the energy and fluence of the incident alpha particles. Additionally, we describe the sources of uncertainty associated with this experiment, including the cell dish repositioning and cell migration during scanning and irradiation.     

Close mapping of the focal non-epidermolytic palmoplantar keratoderma (PPK) locus associated with oesophageal cancer (TOC)

Focal non-epidermolytic palmoplantar keratoderma (PPK or palmoplantar ectodermal dysplasia type III) is associated with oesophageal cancer in three families: two large pedigrees located in Liverpool, UK and in the midwestern American states and one smaller family from Germany. In these families, the PPK is inherited as autosomal dominant and has a late onset, usually manifesting between 7 and 8 years of age. The disease is characterised by thickening of the pressure areas of the soles, but is not restricted to the feet and also presents with oral leukokeratosis and follicular hyperkeratosis. The disease locus [previously termed the "tylosis oesophageal cancer gene' (TOC) locus] has been mapped to 17q23-qter by linkage analysis. This region is located telomeric to the keratin 16 gene, in which mutations have been identified in focal PPK families who show no increased cancer risk. We describe the close mapping of this locus to the interval between AFMb054zf9 and D17S1603 using haplotype analysis of additional Genethon markers in the region and show that although the American family is unlikely to be related to either of the other two, the UK and German pedigrees may share a common descent. This work provides a basis for positional cloning and candidate gene analysis in order to identify a gene that may be involved in familial oesophageal cancer.      

A New Retrieval System for Cement-Retained Implant Superstructures: A Technical Report

This article discusses two methods for improving the retrievability of cement-retained implant superstructures. One method involves incorporating a removal screw in the superstructure and the second method uses a small dimple on the abutment, accessed through a vent in the superstructure.     

Incipient ovarian failure associated with raised levels of follicle stimulating hormone and reduced levels of inhibin A in older sheep

In women there is a gradual rise in the basal level of follicle stimulating hormone (FSH) in the years prior to the menopause (pre- menopause) which is thought to be due to a relative lack of ovarian factors reflecting the number of antral follicles present in the ovaries. Experimental animal models for this phenomenon, particularly in mono-ovulatory species, have been lacking due to most animals' relatively short life span. We have available a group of experimental ewes in which the right ovary was removed and the left ovary was autotransplanted to the neck at least 10 years previously, which have been maintained in good health until an age of 12-13 years. Two experiments were conducted with these animals to determine the endocrine and follicular effects of age: a retrospective experiment in the same Finn-Merino ewes (n = 5) when the animals were 6-7 or 12-13 years of age; and a cohort experiment in old (12-13 years, n = 6) and young (2 years, n = 5) ewes of the same breed. In both retrospective and cohort experiments, the concentrations of FSH were significantly higher (P < 0.05) in older animals during the luteal phase when oestradiol secretion was low. This increase in FSH was associated with a decrease in the concentration of inhibin A (P < 0.05) in older animals in both the follicular and luteal stages of the cycle but the concentrations of oestradiol were similar between ages. Although there were significantly fewer antral follicles (P < 0.05) available for development in older ewes during the early luteal phase of the cycle, the ovulation rate was similar to that observed in younger animals (2.0+/-0 vs 2.0+/-4; P > 0.05) but the interval from luteal regression to the onset of the LH surge was longer (P < 0.05) in older animals. In conclusion, the endocrine changes associated with increasing reproductive age in sheep are therefore similar to those observed in women, suggesting that the sheep could be a useful animal model to study the effect of age on human fertility.      

International Salmonella Typhimurium DT104 infections, 1992-2001

The incidence of multidrug-resistant (MDR) Salmonella Typhimurium infections in humans, and in particular MDR definitive phage type 104 (DT104), has increased substantially in many countries in the last 2 decades, often associated with increased illness. To examine the magnitude of this problem, a survey was conducted among countries with available antimicrobial resistance or phage typing surveillance data. A total of 29, primarily industrialized, countries participated in the survey, which covered the years 1992-2001. Overall, the incidence of MDR S. Typhimurium and DT104 increased continuously during this period, although the problem affected primarily Europe and North America. The increase appeared to have peaked in the United Kingdom but not in other countries. Also, the incidence of quinolone-resistant S. Typhimurium was increasing. This survey implies that MDR S. Typhimurium constitutes an increasing public health problem in large parts of the world and emphasizes the importance of surveillance and control programs.     

Transdermal delivery of naltrexone and its active metabolite 6-beta-naltrexol in human skin in vitro and guinea pigs in vivo

The aim of the present study was to evaluate the transdermal delivery of 6-beta-naltrexol (NTXOL), the active metabolite of naltrexone (NTX), across human skin and guinea pig skin in vitro and in hairless guinea pigs in vivo. NTXOL may be responsible for much of NTX's pharmacologic activity. In vitro diffusion studies on NTXOL were compared with similar studies on NTX using a formulation of propylene glycol and buffer in a flow-through diffusion cell system. In vivo guinea pig studies were carried out involving topical application of both drugs in patches containing identical formulations. The in vitro flux of NTX was about 2.3- and 5.6-fold higher than for NTXOL across guinea pig skin and human skin, respectively. NTXOL lag times were longer than NTX in both skin types. In vivo studies in guinea pigs showed that the steady-state plasma level of NTX was twofold greater than NTXOL, which correlated well with in vitro data. The results of the present study indicated that substantial levels of NTX and NTXOL could be delivered via the transdermal route, although the plasma levels of NTXOL were significantly less than NTX. Further transdermal formulation development will be investigated for permeation enhancement.     

Recombinant raccoon pox vaccine protects mice against lethal plague

Using a raccoon poxvirus (RCN) expression system, we have developed new recombinant vaccines that can protect mice against lethal plague infection. We tested the effects of a translation enhancer (EMCV-IRES) in combination with a secretory (tPA) signal or secretory (tPA) and membrane anchoring (CHV-gG) signals on in vitro antigen expression of F1 antigen in tissue culture and the induction of antibody responses and protection against Yersinia pestis challenge in mice. The RCN vector successfully expressed the F1 protein of Y. pestis in vitro. In addition, the level of expression was increased by the insertion of the EMCV-IRES and combinations of this and the secretory signal or secretory and anchoring signals. These recombinant viruses generated protective immune responses that resulted in survival of 80% of vaccinated mice upon challenge with Y. pestis. Of the RCN-based vaccines we tested, the RCN-IRES-tPA-YpF1 recombinant construct was the most efficacious. Mice vaccinated with this construct withstood challenge with as many as 1.5 million colony forming units of Y. pestis (7.7 x 10(4)LD(50)). Interestingly, vaccination with F1 fused to the anchoring signal (RCN-IRES-tPA-YpF1-gG) elicited significant anti-F1 antibody titers, but failed to protect mice from plague challenge. Our studies demonstrate, in vitro and in vivo, the potential importance of the EMCV-IRES and secretory signals in vaccine design. These molecular tools provide a new approach for improving the efficacy of vaccines. In addition, these novel recombinant vaccines could have human, veterinary, and wildlife applications in the prevention of plague.     

Cytotoxicity as an indicator for transport mechanism: evidence that murine bone marrow progenitor cells lack a high-affinity leucine carrier that transports melphalan in murine L1210 leukemia cells

Cytotoxicity of melphalan to murine L1210 leukemia cells was reduced to a limiting maximum value of 50% by 2-aminobicyclo[2,2,1]heptane-2- carboxylic acid (BCH), indicating that cytotoxicity is partially dependent on drug uptake by system L. L-Leucine, but not alpha- aminoisobutyric acid (AIB), completely reduced the remaining 50% of drug cytotoxicity. These results contrast with those obtained with a sensitive host tissue, the bone marow progenitor cells of the white cell series (CFU-C), in that a high-affinity leucine transport system corresponding to system L was not identified.     

Denture stomatitis with multiple intramucosal fistulae

Abstract – A hitherto undescribed clinical and histologic entity occurring in the palate of 13 denture-wearing patients is described. Clinically it is characterized by the presence of small yellowish areas in the hard palate, which on pressure yield a whitish creamy material through multiple openings. The surrounding mucosa may exhibit various degrees of erythema. The histologic changes are characterized by the presence of intramucosal fistulae lined with unkeratinized squamous epithelium. The content of the fistulae, which corresponds to the creamy material expelled, consists of desquamated epithelial cells. These changes have mostly been nodced in elderly females, all wearing maxillary dentures for many years. This entiPf is considered a type of demure stomatitis characterized by intramucosal proliferation of epithelium, possibly because of long-standing chronic irritation from dentures. The origin of the intramucosal fistulae is unknown. The fistulae are believed to originate either from the ductus of the minor salivary glands or from the surface epithelium of the palate.     

Intermediate lymphocytic lymphoma: immunophenotypic and cytogenetic findings

A detailed immunohistologic and cytogenetic analysis of 12 cases of intermediate lymphocytic lymphoma was performed. The characteristic immunophenotype of intermediate lymphocytic lymphoma was: surface IgM and IgD+, BA1+, B1+, BA2-, B2-, B4+, Leu 14+, Leu 1+, HLA-DR+, and common acute lymphocytic leukemia associated (CALLA) antigen negative. Clonal chromosome abnormalities were identified in ten cases, with structural or numerical abnormalities of chromosomes 11 or 12 in nine cases. Five cases had structural abnormalities involving the long arm of chromosome 11; three of these had translocations with chromosome 14 at band q32. Three cases had trisomy 12, and one case had a translocation involving the long arm of chromosome 12. The tenth case had a translocation involving the long arms of chromosomes 7 and 9. These characteristic immunophenotypic and cytogenetic findings suggest a close lineage relationship between intermediate lymphocytic lymphoma and small lymphocytic (well differentiated) lymphoma/chronic lymphocytic leukemia. Their differing clinical, cytologic, and architectural features suggest, however, that intermediate lymphocytic lymphoma should be considered a separate category of lymphocytic lymphoma in the International Working Formulation.