A reduced model of DA neuronal dynamics that displays quiescence, tonic firing and bursting.

Midbrain dopaminergic neurons send numerous projections to cortical and sub-cortical areas, and in a manner dependent upon their activities, diffusely release dopamine (DA) to their targets. Recent experimental studies have shown that DAergic neuronal bursting is associated with a significantly greater degree of DA release than an equivalent tonic activity pattern. Past computational models for DA cell activity relied upon somatodendritic mechanisms in order to generate DA neuronal bursting. However, recent experimental studies indicate that burst firing can be generated somatically with the dendrites silenced. These somatically induced bursts have characteristics consistent with normal bursting, suggesting that a single-compartmental model should be sufficient for generating the observed DA neuronal dynamics. In this work, we introduce such a model for DA neuronal dynamics and demonstrate that this model captures the qualitative behavior of DAergic neuronal dynamics: quiescence, tonic firing and bursting. In our conductance-based approach, the interplay between the L-type calcium and the calcium dependent SK potassium channel provides a scaffold for the underlying oscillation for the pacemaker-like firing patterns. The model includes terms which can selectively block the SK conductance, which would correspond to pharmacological manipulations using the drug apamin. Our modeling studies are in line with experimental evidence that a reduction of the SK conductance often induces DA neuronal bursting. Moreover, our model can reproduce findings that burst firing can be elicited via stimulus driven events, manifested by rises in the amount of NMDA. This model for DA cell activity could be further sculpted to include more detailed second messenger signaling processes in order to elucidate key differences between the two principal classes of midbrain DA neurons: those of the ventral tegmental area and the substantia nigra pars compacta.

HIV and HCV health beliefs in an inner-city community.

Chronic infection with the hepatitis C virus (HCV) is more prevalent than human immunodeficiency virus (HIV) infection, but more public health resources are allocated to HIV than to HCV. Given shared risk factors and epidemiology, we compared accuracy of health beliefs about HIV and HCV in an at-risk community. Between 2002 and 2003, we surveyed a random patient sample at a primary care clinic in New York. The survey was organized as domains of Common Sense Model of Self-Regulation: causes ('sharing needles'), timeline/consequences ('remains in body for life', 'causes cancer') and controllability ('I can avoid this illness', 'medications may cure this illness'). We compared differences in accuracy of beliefs about HIV and HCV and used multivariable linear regression to identify factors associated with relative accuracy of beliefs. One hundred and twenty-two subjects completed the survey (response rate 42%). Mean overall health belief accuracy was 12/15 questions (80%) for HIV vs 9/15 (60%) for HCV (P < 0.001). Belief accuracy was significantly different across all domains. Within the causes domain, 60% accurately believed sharing needles a risk factor for HCV compared to 92% for HIV (P < 0.001). Within the timeline/consequences domain, 42% accurately believed HCV results in lifelong infection compared to 89% for HIV (P < 0.001). Within the controllability domain, 25% accurately believed that there is a potential cure for HCV. Multivariable linear regression revealed female gender as significantly associated with greater health belief accuracy for HIV. Thus, study participants had significantly less accurate health beliefs about HCV than about HIV. Targeting inaccuracies might improve public health interventions to foster healthier behaviours and better hepatitis C outcomes.

Utilizing an electronic health record system to improve vaccination coverage in children.

BACKGROUND: Electronic Health Records (EHR) are widely believed to improve quality of care and effectiveness of service delivery. Use of EHR to improve childhood immunization rates has not been fully explored in an ambulatory setting. OBJECTIVE: To describe a pediatric practice's use of Electronic Health Records (EHR) in improving childhood immunization. METHODS: A multi-faceted EHR-based quality improvement initiative used electronic templates with pre-loaded immunization records, automatic diagnosis coding, and EHR alerts of missing or delayed vaccinations. An electronic patient tracking system was created to identify patients with missing vaccines. Barcode scanning technology was introduced to aid speed and accuracy of documentation of administered vaccines. Electronic reporting to a local health department immunization registry facilitated ordering of vaccines. RESULTS: Immunization completion rates captured in monthly patient reports showed a rise in the percentage of children receiving the recommended series of vaccination (65% to 76%) (p<0.000). Barcode technology reduced the time of immunization documentation (86 seconds to 26 seconds) (p<0.000). Use of barcode scanning showed increased accuracy of documentation of vaccine lot numbers (from 95% to 100%) (p<0.000). CONCLUSION: EHR-based quality improvement interventions were successfully implemented at a community health center. EHR systems have versatility in their ability to track patients in need of vaccines, identify patients who are delayed, facilitate ordering and coding of multiple vaccines and promote interdisciplinary communication among personnel involved in the vaccination process. EHR systems can be used to improve childhood vaccination rates.

Herceptest: HER2 expression and gene amplification in non-small cell lung cancer.

HER2 is an erbB/HER type 1 tyrosine kinase receptor that is frequently over-expressed in malignant epithelial tumours. Herceptin, a humanised mouse monoclonal antibody to HER2, is proven therapeutically in the management of metastatic breast cancer, significantly prolonging survival when combined with cytotoxic chemotherapeutic agents. Immunohistochemical studies suggest that non-small-cell lung cancer (NSCLC) tumours may over-express HER2. Our aim was to evaluate HER2 gene amplification and semi-quantitative immuno-expression in NSCLC. A total of 344 NSCLC cases were immunostained for HER2 expression in 2 centres using the HercepTest. Fluorescence in situ hybridisation (FISH) analysis for HER2 gene amplification was performed on most positive cases and a subset of negative cases. Fifteen cases (4.3%) demonstrated 2+ or 3+ membranous HER2 immuno-expression. There was no correlation between immuno-expression and tumour histology or grade. Tumours from higher-stage disease were more often HercepTest-positive (p < 0.001). All 4 HercepTest 3+ cases demonstrated gene amplification. One of the 5 2+ cases tested for gene amplification showed areas of borderline amplification and areas of polyploidy. None of the 19 HercepTest-negative cases demonstrated gene amplification or polyploidy (p < 0.001). Gene amplification was demonstrated in all HercepTest 3+ scoring NSCLC cases. Unlike breast cancer, gene amplification and HER2 protein over-expression assessed by the HercepTest appeared to be uncommon in NSCLC. Herceptin may therefore target only a small proportion of NSCLC tumours and be of limited clinical value in this disease, particularly in the adjuvant setting.

Bilateral rhegmatogenous retinal detachments with unilateral vitreous base avulsion as the presenting signs of child abuse.

PURPOSE: To describe a 7-year-old boy with bilateral rhegmatogenous retinal detachments and unilateral vitreous base avulsion as the presenting signs of child abuse. METHOD: Case report. RESULTS: Examination demonstrated no external signs of trauma or ocular findings typically found in battered child syndrome; however, findings of rhegmatogenous retinal detachments and vitreous base avulsion raised the suspicion of child abuse, which was confirmed with further history. A scleral buckle procedure and pars plana vitrectomy with silicone oil tamponade were performed in the right eye followed by a similar procedure in the left eye 1 week later. CONCLUSION: Vitreous base avulsion and rhegmatogenous retinal detachments may be the only presenting signs of child abuse.

Rat endocrine pancreatic development in relation to two homeobox gene products (Pdx-1 and Nkx 6.1).

We studied the distribution of the homeodomain proteins Pdx-1 and Nkx 6.1 in the developing rat pancreas. During early development, nuclear staining for both Pdx-1 and Nkx 6.1 occurred in most epithelial cells of the pancreatic anlage. Subsequently, Nkx 6.1 became more beta-cell-restricted, and Pdx-1 also occurred in other islet cell types and in the duodenal epithelium. During early pancreatic development, cells co-storing insulin and glucagon were regularly detected. The vast majority of these did not possess nuclear staining for either Pdx-1 or Nkx 6.1. Subsequently, cells storing insulin only appeared. Such cells displayed strongly Pdx-1- and Nkx 6.1-positive nuclei. Therefore, Nkx 6.1, like Pdx-1, may be an important factor in pancreatic development and in mature insulin cell function.

Homeobox gene product Nkx 6.1 immunoreactivity in nuclei of endocrine cells of rat and mouse stomach.

The homeobox gene product Nkx 6.1 is of unknown function but is expressed in the pancreas and the antropyloric mucosa of the stomach. In the adult pancreas, Nkx 6.1 possesses an insulin cell-restricted distribution, whereas its localization in the stomach is unknown. We now show that the vast majority of serotonin-producing enterochromaffin cells of the antropyloric mucosa contain Nkx 6. 1-immunoreactive nuclei. In addition, a subpopulation of cells co-storing serotonin and gastrin display Nkx 6.1-positive nuclei. Such cells have been postulated to represent precursors of mature gastrin and serotonin cells. The nuclei of the co-storing cells have previously also been found to be positive for another homeodomain protein, Pdx-1. Pdx-1-deficient animals were therefore investigated and were found to be devoid of Nkx 6.1-positive nuclei. Our data show that Pdx-1 is needed for Nkx 6.1 expression and suggest a role for Nkx 6.1 in the maturation of gastrin- and serotonin-positive precursor cells.

Transcription factors contributing to the pancreatic beta-cell phenotype.

Insulin promoter factor-1 (IPF1) (renamed to pancreatic-duodenal homeobox factor-1, PDX1) was originally cloned and characterized as an islet beta-cell specific insulin gene transcription factor (1) and later shown to be essential for the formation of the mature pancreas (2, 3). In the adult normal pancreas PDX1 is almost exclusively expressed in the beta-cell compartment and generally absent from the alpha-cell while it is widely expressed in the pancreatic epithelium during development. Using pluripotent rat islet tumor cultures and derived insulinomas and glucagonomas we have analyzed differential expression of a large number of genes including the transcription factors PDX1, Nkx6.1, Pax6, and NeuroD. While NeuroD and Pax6 expression was detectable among all phenotypes, PDX1 was expressed in the pluripotent culture and maintained in the insulinoma, while Nkx6.1 was selectively co-induced with insulin during insulinoma formation. Both factors were not detectable in the glucagonoma. Nkx6.1 proved to have a highly beta-cell restricted expression in the adult rat. Forced expression of recombinant PDX1 in the glucagonoma resulted in efficient transcriptional activation of the endogenous insulin and IAPP genes, but did not affect glucagon gene activity. In this hybrid alpha/beta-cell phenotype the endogenous Nkx6.1 gene remained silent. We conclude that PDX1 in synergy with NeuroD specifies part of the beta-cell phenotype including transcriptional activation of insulin and IAPP genes, but that other factors such as Nkx6.1 and Pax6 are required for additional features of the fully mature beta-cell phenotype.

Non-primary cervical adenocarcinomas.

We reviewed 16 non-primary cervical adenocarcinomas collected during a six year period. Ten tumors originated in the endometrium, three in the ovary and one each in the bladder, colon and fallopian tube. Tumor spread was identified by combined lymphovascular involvement and stromal invasion in five of the 16 cervices, lymphovascular involvement alone in four cervices, stromal invasion alone in two cervices, lymphovascular involvement with stromal invasion and cervical implantation in two cervices and cervical implantation alone in three cervices. The three tumors with surface implantation alone were of endometrial origin, had minimal if any myometrial invasion, no extrauterine metastases and two had malignant peritoneal washings. Of the 13 tumors with cervical lymphovascular involvement and/or stromal metastases, 11 had ovarian, nodal and/or peritoneal metastases. We conclude that cervical implantation occurs exclusively with endometrial adenocarcinomas, that it follows previous cervical instrumentation and that the prognosis is dependent on the histoprognostic features of the primary endometrial tumor. In contrast, cervical lymphovascular involvement and/or stromal metastases usually reflects disseminated pelvic or abdominal malignancy with a poor prognosis. However histological examination may not afford separation of these two lesions if local cervical invasion is advanced, if spread has occurred by more than one mode or if insufficient clinical/surgical information is provided.

PYY in developing murine islet cells: comparisons to development of islet hormones, NPY, and BrdU incorporation.

Exhaustive characterizations of antisera to the structurally related peptides pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY) enabled us to establish the developmental pattern of these peptides in rat and mouse pancreas. PYY was the earliest detectable peptide and was present in all early appearing endocrine cell types. NPY appeared later and occurred exclusively in a subpopulation of insulin cells, whereas PP cells arose latest. At the earliest stage studied, all endocrine cells stored PYY. Most of these cells also contained glucagon. Subsequently, the endocrine cells comprised glucagon+PYY cells and glucagon+PYY+insulin cells. Later, cells storing either only insulin or insulin+PYY appeared. Quantitations of the relative numbers of these cell populations during development were consistent with a precursor role of triple-positive (insulin+glucagon+PYY) cells. Moreover, bromodeoxyuridine (BrdU) injections at E15.5 showed that a large percentage of triple-positive cells were in S-phase and therefore were actively dividing, whereas almost no pure insulin cells or insulin+PYY cells synthesized DNA at this time. These results suggest that PYY-positive endocrine cells may represent precursors for mature islet cells.

A comparison of the immunogenicity of the native and denatured forms of a protein.

The effect of heat denaturation on the physicochemical and immunological properties of a model protein, ovalbumin, and its formaldehyde/lysine-treated form was investigated. Polyacrylamide gel electrophoresis and gel filtration showed that heat denaturation converted ovalbumin to high Mr polymers, whereas formaldehyde/lysine-treated ovalbumin remained monomeric with only a small proportion forming oligomers. NMR analysis demonstrated that non-denatured structures could easily be differentiated from the denatured structures. Intraperitoneal immunization of rabbits and mice showed that both native and denatured forms of ovalbumin induced an immune response, but denatured forms of ovalbumin were found to be less immunogenic and to have a lower epitope density than native ovalbumin. Analysis of the antisera in crossed immunoelectrophoresis showed that they were specific for either native or denatured forms of ovalbumin. These findings were further investigated by ELISA and immunoaffinity chromatography, and the high specificity and low cross-reactivity was confirmed. We conclude that the immunogenic epitopes on denatured ovalbumin are different from those on ovalbumin, and that these epitopes reflect a continuum of denatured conformations.

Efficient method for constructing comprehensive murine Fab antibody libraries displayed on phage.

We have developed efficient methodologies for construction and expression of comprehensive phage display libraries of murine Fab antibody fragments in E. coli cells. Our methods optimize several critical steps of the polymerase chain reaction (PCR) amplification of transcripts of the re-arranged immunoglobulin genes and of their subsequent assembly and expression: Firstly, we have designed exhaustive sets of PCR primers of low degeneracy for the amplification of transcripts of the Fab region of the heavy and light-chain genes. These primers proved effective in amplification of Fab gene fragments from a large panel of hybridoma cell lines of different specificity and family sub-type. Secondly, we have developed a 'jumping PCR' technique that effectively assembled and recombined the amplified heavy and light-chain gene fragments into a bi-cistronic operon. Thirdly, we have constructed expression vectors for insertion of the combinatorial Fab gene-cassette in fusion with a truncated version of the phage surface protein, gIIIp. The heavy chain and the light chain-gIII fusion are transcribed as a polycistronic mRNA from the lacZ promoter and efficient transcriptional control is provided by wildtype lacI present on the vector. The utility of the system was demonstrated by isolating several antigen-binding clones from hybridomas and libraries made from immunized mice.