Search PubMed⌕ Search

Biomedical subjects

N Fox

Publications and source records attributed to N Fox.

At least 19 recordsLinked to original sources
PubMed2000

A novel procedure for efficient genotyping of single nucleotide polymorphisms.

Due to the surge in interest in using single nucleotide polymorphisms (SNPs) for genotyping a facile and affordable method for this is an absolute necessity. Here we introduce a procedure that combines an easily automatable single tube sample preparation with an efficient high throughput mass spectrometric analysis technique. Known point mutations or single nucleotide polymorphisms are easily analysed by this procedure. It starts with PCR amplification of a short stretch of genomic DNA, for example an exon of a gene containing a SNP. By shrimp alkaline phosphatase digest residual dNTPs are destroyed. Allele-specific products are generated using a special primer, a conditioned set of alpha-S-dNTPs and alpha-S-ddNTPs and a fresh DNA polymerase in a primer extension reaction. Unmodified DNA is removed by 5'-phospho-diesterase digestion and the modified products are alkylated to increase the detection sensitivity in the mass spectrometric analysis. All steps of the preparation are simple additions of solutions and incubations. The procedure operates at the lowest practical sample volumes and in contrast to other genotyping protocols with mass spectrometric detection requires no purification. This reduces the cost and makes it easy to implement. Here it is demonstrated in a version using positive ion detection on described mutations in exon 17 of the amyloid precursor protein gene and in a version using negative ion detection on three SNPs of the granulocyte-macrophage colony stimulating factor gene. Preparation and analysis of SNPs is shown separately and simultaneously, thus demonstrating the multiplexibility of this genotyping procedure. The preparation protocol for genotyping is adapted to the conditions used for the SNP discovery method by denaturing HPLC, thus demonstrating a facile link between protocols for SNP discovery and SNP genotyping. Results corresponded unanimously with the control sequencing. The procedure is useful for high throughput genotyping as it is required for gene identification and pharmacogenomics where large numbers of DNA samples have to be analysed. We have named this procedure the 'GOOD Assay' for SNP analysis.

Amyloid beta-Protein Precursor↗
PubMed2000

EEG correlates of the development of infant joint attention skills.

The development of the capacity for social attention coordination, or "joint attention," is a major milestone of infancy. Data from a recent study of handicapped infants have raised the hypothesis that the tendency to initiate bids for joint attention may reflect processes associated with the frontal cortex to a greater extent than other forms of infant attention coordination (R. Caplan et al., 1993). This hypothesis was examined in a longitudinal study of 32 normally developing infants. The results indicated that EEG data at 14 months indicative of left frontal, as well as left and right central cortical activity, was associated with the tendency to initiate joint attention bids (IJA) at 14 and 18 months. In contrast, a pattern of left parietal activation and right parietal deactivation at 14 months was associated with the development of the capacity to respond to the joint attention bids (RJA) of others at 14 and 18 months. These results were interpreted to be consistent with a general anterior-posterior model of attention development (M. Posner & S. Petersen, 1990). The implications of these results for current conceptualizations of joint attention development, as well as for understanding the disturbance of joint attention skill development in autism are discussed.

Attention↗
PubMed1999

Spatial working memory in Asperger's syndrome and in patients with focal frontal and temporal lobe lesions.

Spatial working memory (SWM) was investigated in 15 patients with Asperger's syndrome (AS) comparing their performance to 18 age- and IQ-matched control subjects. An additional comparison was made with 20 unilateral frontal excision patients [9 right (RFL); 11 left (LFL)] and with 38 unilateral temporal lobectomy patients [18 right (RTL); 18 left (LTL)], the frontal and temporal lobe patients having separate matched control groups. SWM was tested using the Executive Golf Task, a test that also measures spatial strategy formation. The AS group showed a substantial deficit on SWM, but no impairment in strategy formation. The LFL showed the same pattern of impairment, but with a less substantial deficit. The RFL group showed a large deficit, but some of this was accounted for by a strategy formation impairment. Of the temporal lobe lesions groups, only the RTL group was impaired on SWM, but this group showed normal strategy formation. It was concluded that the SWM deficit in AS may reflect a more general difficulty in accessing different types of representations in order to guide voluntary behavior, providing at least a partial explanation for the executive deficits found in AS.

Adolescent↗
PubMed1999

Differences in amyloid deposition in islets of transgenic mice expressing human islet amyloid polypeptide versus human islets implanted into nude mice.

Islet amyloid polypeptide (IAPP)-derived amyloid is frequently deposited in the islets of Langerhans in patients with chronic non-insulin-dependent diabetes mellitus (NIDDM). When human islets were implanted under the renal capsule in nude mice, amyloid occurred in 73% of the grafts within 2 weeks. In this study, we compare the deposition of amyloid in islets from a transgenic mouse strain expressing human IAPP (hIAPP) and in normal human islets after implantation in nude mice. The implantations were performed as follows: (1) nondiabetic recipients were given islets from transgenic mice alone, (2) human islets were implanted in the upper pole of the kidney and islets from transgenic mice were implanted in the lower pole of the kidney, (3) grafts containing a mixture of human and transgenic islets were implanted, and (4) transgenic islets and islets from nontransgenic littermates were implanted in therapeutic numbers into recipients made diabetic by a single injection of alloxan prior to implantation. The implants were removed after various periods from 4 days to 8 weeks. The implants were either fixed in Formalin, stained for amyloid, and viewed in polarized light, or processed for immunoelectron microscopy and studied after immunolabeling with specific antibodies against IAPP. We found that the course of amyloid deposition differed significantly between human islets and hIAPP-expressing mouse islets. In human islets, amyloid was mainly deposited intracellularly and only small amounts of amyloid were found extracellularly. In contrast, in islets from transgenic mice, amyloid was exclusively deposited extracellularly and deposition in this site was preceded by an aggregation of immunoreactive material along the basement membrane. These findings point to separate mechanisms for amyloid formation in these two models.

Amyloid↗
PubMed1999

The Wisdom Project: virtual education in primary care.

This article examines the development of the Wisdom Project, a pilot for the teaching of informatics to primary health care professionals, using an original educational model based on e-mail and Web pages. The article begins by placing the development of the Wisdom Project in the context of changes in medical education and training. The aims and objectives of Wisdom are outlined, and the methodologies for setting up and evaluating the project are described. The article then presents the results of the evaluation, including the identification of significant improvements in knowledge of CD ROMs (P = 0.01), e-mail (P = 0.03), Medline (P = 0.02), operating systems (P = 0.02), Web browsers (P = 0.003) and word processing (P = 0.03). Improvements in evidence-based practice (EBP) did not reach significance. Finally, a number of conclusions are presented, considering the lessons learnt for the future development of such projects.

Attitude to Computers↗
PubMed1999

Pharmacology of LY315920/S-5920, [[3-(aminooxoacetyl)-2-ethyl-1- (phenylmethyl)-1H-indol-4-yl]oxy] acetate, a potent and selective secretory phospholipase A2 inhibitor: A new class of anti-inflammatory drugs, SPI.

LY315920 is a potent, selective inhibitor of recombinant human, group IIA, nonpancreatic secretory PLA2 (sPLA2). In a chromogenic isolated enzyme assay, LY315920 inhibited sPLA2 activity with an IC50 of 9 +/- 1 nM or 7.3 x 10(-6) mole fraction, which approached the stiochiometric limit of this assay. The true potency of LY315920 was defined using a deoxycholate/phosphatidylcholine assay with a mole fraction of 1.5 x 10(-6). LY315920 was 40-fold less active against human, group IB, pancreatic sPLA2 and was inactive against cytosolic PLA2 and the constitutive and inducible forms of cyclooxygenase. Human sPLA2-induced release of thromboxane A2 (TXA2) from isolated guinea pig lung bronchoalveolar lavage cells was inhibited by LY315920 with an IC50 of 0.79 microM. The release of TXA2 from these cells by N-formyl-methionyl-leucyl-phenylalanine or arachidonic acid was not inhibited. The i.v. administration of LY315920, 5 min before harvesting the bronchoalveolar lavage cells, resulted in the inhibition of sPLA2-induced production of TXA2 with an ED50 of 16.1 mg/kg. Challenge of guinea pig lung pleural strips with sPLA2 produced contractile responses that were suppressed in a concentration-dependent manner by LY315920 with an apparent KB of 83 +/- 14 nM. Contractile responses induced by arachidonic acid were not altered. Intravenous or oral administration of LY315920 to transgenic mice expressing the human sPLA2 protein inhibited serum sPLA2 activity in a dose-related manner over a 4-h time course. LY315920 is a potent and selective sPLA2 inhibitor and represents a new class of anti-inflammatory agent designated SPI. This agent is currently undergoing clinical evaluation and should help to define the role of sPLA2 in various inflammatory disease states.

Acetates↗
PubMed1998

General practitioners and the Internet: modelling a 'virtual community'.

BACKGROUND: Electronic discussion lists are used by many groups, including GPs, for communication and information sharing. The technology offers potential for formal learning and professional development. Various models have been proposed to describe the dynamics of such 'virtual' forums, and research is required to explore how such a discussion list might support professional development. OBJECTIVE: We aimed to explore the use of the Internet-based discussion group gp-uk by GPs and their colleagues. METHODS: We carried out a qualitative study of the electronic text generated by GPs and colleagues on an academic medical discussion group. RESULTS: The list gp-uk has features of a collaborative medium, in which the audience are also contributors. There is support for a 'critical mass' model, in which a relatively small number of members contribute on a regular basis. There is little support for a 'discretionary database' model of more formal sharing of specific factual information. CONCLUSIONS: The findings indicate a model for a 'virtual classroom' for computer-mediated learning and professional development. A critical mass of participants is a requisite, the list should be facilitated to guide discussions and supporting resources such as an Internet web-site should be provided.

Computer Communication Networks↗
PubMed1998

PACE: a model for integrated care of frail older patients. Program of All-inclusive Care for the Elderly.

The Program of All-inclusive Care for the Elderly (PACE) is a model of care that pools Medicare and Medicaid funds to provide acute and long-term care services for older patients through the use of interdisciplinary teams. Services include physician visits, prescription drugs, rehabilitation services, personal care workers, hospitalization, and nursing home care, if needed. PACE programs may also offer social services intervention, case management, respite care, or extended home care nursing. The PACE site assumes financial responsibility for all services. Now that PACE programs can become permanent providers under Medicare, their number is expected to grow.

Aged↗
PubMed1997

The professional perception of orthodontic treatment complexity.

OBJECTIVE: To assess the current professional concept of orthodontic treatment complexity. DESIGN: Cross sectional survey of practitioners' views towards recently completed orthodontic treatments. SETTING: Specialist and non-specialist practitioners in General Dental Services in North Western and Mersey regions. The sampling was carried out between 1993-95. SUBJECTS AND METHODS: All practitioners undertaking orthodontic treatments in the GDS in the North Western and Mersey regions were invited to participate. Practitioners submitted consecutively started cases for scrutiny by analysis of study models and pre-treatment and post-treatment questionnaires. 280 cases were collected. Data were analysed using multiple linear regression. MAIN OUTCOME MEASURES: The occlusal changes were assessed using the Index of Orthodontic Treatment Need and the Peer Assessment Rating. Self administered questionnaires employed 5-point Likert type scales to record practitioners' and patients' opinions. RESULTS: It appears that the concept of complexity is related to the occlusal changes which occur during orthodontic treatment. Attempts to define treatment complexity identifies factors which are of questionable validity and could be easily manipulated in practice setting. CONCLUSIONS: The present concepts of treatment complexity appear to be somewhat flawed. There is no occlusal index of complexity which is particularly satisfactory but as a crude interim measure 3 grades of complexity are proposed based on the PAR index.

Adolescent↗
PubMed1997

Cellular delivery of NGF does not alter the expression of beta-amyloid immunoreactivity in young or aged nonhuman primates.

The present study determined whether grafts of nerve growth factor-producing fibroblasts alter the expression of beta-amyloid in young or aged nonhuman primates. Aged monkeys serve as an animal model which normally exhibits beta-amyloid-laden plaques. Three young adult (7-12 years of age) and three aged (24-29 years of age) rhesus monkeys received intraventricular implants of polymer-encapsulated cells that were genetically modified to secrete human recombinant nerve growth factor (NGF). Three young adult and three aged rhesus monkeys received identical treatment except that the grafted cells were not genetically modified and thus differed only by a single gene construct. Five additional aged rhesus monkeys were ungrafted and also served as controls. Three to four weeks posttransplantation, young monkeys did not display beta-amyloid-immunoreactive profiles within any CNS structure regardless of treatment. Qualitative observations revealed that aged monkeys displayed numerous beta-amyloid plaque-like structures within the amygdala and hippocampus as well as limbic and neocortices. The amount of beta-amyloid immunoreactivity (beta-amyloid load) was quantified bilaterally within the temporal neocortex of these animals. The beta-amyloid load within the temporal neocortex of aged monkeys was highly variable but did not differ across treatment groups. These data indicate that chronic short-term administration of NGF does not affect the expression of beta-amyloid in the young or the aged primate brain.

Aging↗
PubMed1997

Empowering research: statistical power in general practice research.

BACKGROUND: Statistical power is a measure of the extent to which a study is capable of discerning differences or associations which exist within the population under investigation, and is of critical importance whenever a hypothesis is tested by statistics. Conventionally, studies should reach a power level of 0.8, such that four times out of five a false null hypothesis will be rejected by a study. Statistical power may most easily be increased by increasing sample size. OBJECTIVE: We aimed to assess the level of statistical power of general practice research. METHODS: A total of 1422 statistical tests in 85 quantitative original papers in the British Journal of General Practice were analysed for statistical power. RESULTS: The median power of tests analysed was 0.71, representing a slightly greater than two-thirds likelihood of rejecting false null hypotheses. Of 85 studies, 37 (44%) attained power of 0.8 or more. Ten studies had power of more than 0.99 suggesting 'over-powering'. Twenty-one of the papers surveyed (25%) had a likelihood of gaining significant results poorer than that obtained by tossing a coin when a null hypothesis is false. CONCLUSION: While achieving higher power than studies in similar surveys of other disciplines, the power of general practice research falls short of the 0.8 convention. Adequate power is essential so that effects which exist are not missed. Recommendations are made concerning power calculations prior to the start of research and reporting of results in journal articles.

Bias↗
PubMed1997

Program of All-inclusive Care for the Elderly (PACE): an innovative model of integrated geriatric care and financing.

OBJECTIVES: The Program of All-inclusive Care for the Elderly (PACE) is a long-term care delivery and financing innovation. A major goal of PACE is prevention of unnecessary use of hospital and nursing home care. SETTING: PACE serves enrollees in day centers and clinics, their homes, hospitals and nursing homes. Beginning at On Lok in San Francisco, the PACE model has been successfully replicated across the country. In 1995, PACE was fully operational in 11 cities in nine states. PARTICIPANTS: To enroll in PACE, a person must be 55 years of age or older, be certified by the state as eligible for care in a nursing home and live in the program's defined geographical catchment area. PACE participants are ethnically diverse. In 1995, the average PACE enrollee was 80.0 years old and had an average of 7.8 medical conditions and 2.7 dependencies in Activities of Daily Living. A significant number have bladder incontinence (55%). Many enrollees (39%) live alone in the community, and 14% have no means of informal support. INTERVENTION: Medicare and Medicaid waivers allow delivery of services beyond the usual Medicare and Medicaid benefits. The PACE service delivery system is comprehensive, uses an interdisciplinary team for care management, and integrates primary and specialty medical care. PACE receives monthly capitation payments from Medicare and Medicaid. Patients ineligible for Medicaid pay privately. RESULTS: Outcomes of PACE programs have been positive. There has been steady census growth, good consumer satisfaction, reduction in use of institutional care, controlled utilization of medical services, and cost savings to public and private payers of care, including Medicare and Medicaid. However, starting up a PACE program requires substantial time and capital, and the model has not yet attracted large numbers of older middle income adults. CONCLUSION: The growing number of older people in the United States challenges healthcare providers and policy makers alike to provide high quality care in an environment of shrinking resources. The PACE model's comprehensiveness of health and social services, its cost-effective coordinated system of care delivery, and its method of integrated financing have wide applicability and appeal.

Aged↗
PubMed1996

Thrombopoietin stimulates colony-forming unit-megakaryocyte proliferation and megakaryocyte maturation independently of cytokines that signal through the gp130 receptor subunit.

Thrombopoietin (Tpo), the ligand for the c-Mpl receptor, is a major regulator of megakaryopoiesis. Treatment of mice with Tpo raises the platelet count fourfold within a few days. Conversely, c-mpl knock-out mice have platelet counts that are 15% that of normal. The subunit structure of the c-Mpl receptor is not fully understood. Some cytokines that stimulate megakaryopoiesis (IL-6, IL-11, leukemia inhibitory factor, and oncostatin M) bind to receptors that use gp130 as a signal transduction subunit. For these reasons, we determined whether gp130 function was required for Tpo-induced signal transduction. Murine marrow cells were cultured in semi-solid media in the presence of Tpo or IL-3, with or without a neutralizing anti-gp130 monoclonal antibody (RX187) or a soluble form of c-Mpl receptor (soluble Mpl) that blocks Tpo bioactivity, and the numbers of colony-forming unit-megakaryocyte (CFU-Meg) colonies were counted on day 5. Murine marrow cells were also cultured in suspension under serum-free conditions for 5 days, and megakaryocyte DNA content was measured by flow cytometry, as an index of nuclear maturation. The addition of RX187 did not block Tpo-induced CFU-Meg colony growth nor CFU-Meg nuclear maturation in suspension culture. However, IL-3-induced CFU-Meg colony growth and megakaryocyte nuclear maturation decreased in the presence of RX187. Soluble Mpl completely ablated Tpo-induced CFU-Meg growth, and partially blocked IL-3-stimulated CFU-Meg growth. Thus the effects of Tpo on megakaryopoiesis in vitro do not depend on cytokines that signal through gp130. Furthermore, it is unlikely that gp 130 serves as a beta chain for the c-Mpl receptor, as Tpo signalling is unimpaired in the presence of RX187. In contrast, the effects of IL-3 on CFU-Meg growth are mediated in part through Tpo and through gp130-signalling cytokines.

Animals↗
PubMed1996

Do dentists refer orthodontic patients inappropriately?

One concern to both providers and consumers of orthodontic treatment is the length of new patient consultation waiting lists. A possible reason for the excessive length of these lists could be unnecessary referral of patients. This research project aimed to identify whether inappropriate referrals for new patient orthodontic consultations were a significant problem. The study was carried out in two FHSA areas in the north of England in two stages. The first part of the study involved an evaluation of GDP referral patterns to orthodontic secondary care providers. In the second part, information on the patients referred by the dentists was collected. We concluded that there was a marked variation in referral rates between the dentists and many patients were referred unnecessarily. Importantly, there was no association between dentists' referral rate and the number of inappropriate referrals made. It appears that referral guidelines for orthodontic treatment are necessary and they should be directed at all general dental practitioners.

Adolescent↗
PubMed1996

Transgenic model for the discovery of novel human secretory non-pancreatic phospholipase A2 inhibitors.

Transgenic mice were created which overexpress human secretory non-pancreatic phospholipase A2 (sPLA2) pansomatically as a potential disease and drug-testing model. The mice were produced using a DNA construct in which the inducible mouse metallothionein gene promoter drives expression of a human sPLA2 minigene. High levels of sPLA2 were detected in several tissues by immunofluorescence localization. Expression in the testes caused hypospermia and male infertility. Circulating catalytically active sPLA2 could be induced to levels observed in patients undergoing a systemic inflammatory response but had no detectable effect on the mice. Therefore, these results suggest that sPLA2 hyperphospholipasemia alone may have only limited pathophysiological consequences. We further show that 3-[3-acetamide-1-benzyl-2-ethylindolyl-5-oxy]propane phosphonic acid LY311727), a potent new inhibitor of phospholipase A2 catalysis developed by our group, dramatically suppresses the circulating enzyme activity in these animals whereas 3-[3-acetamide-1-benzyl-2-propylindolyl-5-oxy]propane phosphonic acid (LY314024), a substantially less potent LY311727 analog, is without effect. These later results thus motivate the further development of this compound as a potential new therapeutic agent and valuable research tool.

Animals↗
PubMed1996

The effect of thrombopoietin on the proliferation and differentiation of murine hematopoietic stem cells.

In this study, we explored whether thrombopoietin (Tpo) has a direct in vitro effect on the proliferation and differentiation of long-term repopulating hematopoietic stem cells (LTR-HSC). We previously reported a cell separation method that uses the fluorescence-activated cell sorter selection of low Hoescht 33342/low Rhodamine 123 (low Ho/low Rh) fluorescence cell fractions that are highly enriched for LTR-HSC and can reconstitute lethally irradiated recipients with fewer than 20 cells. Low Ho/low Rh cells clone with high proliferative potential in vitro in the presence of stem cell factor (SCF) + interleukin-3 (IL-3) + IL-6 (90% to 100% HPP-CFC). Tpo alone did not induce proliferation of these low Ho/low Rh cells. However, in combination with SCF or IL-3, Tpo had several synergistic effects on cell proliferation. When Tpo was added to single growth factors (either SCF or IL-3 or the combination of both), the time required for the first cell division of low Ho/low Rh cells was significantly shortened and their cloning efficiency increased substantially. Moreover, the subsequent clonal expansion at the early time points of culture was significantly augmented by Tpo. Low Ho/low Rh cells, when assayed in agar directly after sorting, did not form megakaryocyte colonies in any growth condition tested. Several days of culture in the presence of multiple cytokines were required to obtain colony-forming units-megakaryocyte (CFU-Mk). In contrast, more differentiated, low Ho/high Rh cells, previously shown to contain short-term repopulating hematopoietic stem cells (STR-HSC), were able to form megakaryocyte colonies in agar when cultured in Tpo alone directly after sorting. These data establish that Tpo acts directly on primitive hematopoietic stem cells selected using the Ho/Rh method, but this effect is dependent on the presence of pluripotent cytokines. These cells subsequently differentiate into CFU-Mk, which are capable of responding to Tpo alone. Together with the results of previous reports of its effects on erythroid progenitors, these results suggest that the effects of Tpo on hematopoiesis are greater than initially anticipated.

Animals↗
PubMed1996

Oral fluconazole compared with bladder irrigation with amphotericin B for treatment of fungal urinary tract infections in elderly patients.

Fungal urinary tract infections are increasingly prevalent in the elderly in acute and chronic care settings. This randomized trial compares the efficacy and safety of oral fluconazole with the efficacy and safety of bladder irrigation with amphotericin B for treatment of funguria (> or = 10,000 cfu/mL of urine) in 109 hospitalized elderly patients. A second treatment course was given for persistent funguria. Indwelling bladder catheters were present in 69% of the patients. While Candida albicans was the predominant isolate from catheterized patients, C. albicans, Candida tropicalis, and Torulopsis glabrata were recovered from noncatheterized patients. Two days after completion of treatment, funguria was eradicated in 96% of the patients treated with amphotericin B and 73% of those treated with fluconazole (P < .05). At 1 month after study enrollment, the mortality rate associated with all causes was greater among patients who were treated with amphotericin B bladder irrigation than among those who received oral fluconazole therapy (41% vs. 22%, respectively; P < .05); this finding suggests that local therapy may be associated with poorer survival. The proportion of patients without funguria at 1 month after study enrollment was similar in the two treatment groups (84%, amphotericin B group; 80%, fluconazole group). A few minor and mild adverse events occurred.

Administration, Oral↗