Biomedical subjects
S Chapman
Publications and source records attributed to S Chapman.
The hot air on passive smoking
Explore the source record for details and available documents.
Bans on smoking in public become more commonplace.
Explore the source record for details and available documents.
Emergency use of cellular (mobile) telephones.
Explore the source record for details and available documents.
General Practice Research Database for prescribing analysis.
Explore the source record for details and available documents.
Safety, pharmacokinetics, and antiretroviral activity of the potent, specific human immunodeficiency virus protease inhibitor nelfinavir: results of a phase I/II trial and extended follow-up in patients infected with human immunodeficiency virus.
The safety, antiretroviral activity, and pharmacokinetic profile of nelfinavir, a potent and specific inhibitor of human immunodeficiency virus (HIV) protease, were assessed in a small open-label phase I/II dose-ranging study in protease inhibitor-naive HIV-positive men. A total of 22 patients with baseline plasma HIV RNA > or = 20,000 copies/mL and CD4+ counts between 200 and 500 cells/mm3 were enrolled in the study. Of the 22 patients, 20 were evaluated for activity; 10 patients assigned to 771 mg/day base equivalent (300 mg three times daily) and 10 patients assigned to 1,026 mg/day base equivalent (600 mg twice daily) given monotherapy. A capsule formulation of nelfinavir was used. The initial study period was 28 days; patients showing a virologic response of 1 log10 reduction were eligible for enrollment in an extension phase and addition of nucleoside analogues. A maximally tolerated dose of nelfinavir was not established. A dose-response relationship was observed for four (40%) patients in the 771-mg group and six (60%) patients in the 1,026-mg group experiencing a reduction from baseline in plasma HIV RNA of at lest 1 log during the 28-day study. Of these patients, five sustained the reduction in plasma HIV RNA beyond day 28 (2 patients receiving 771 mg/day and 3 patients receiving 1,026 mg/day). Median increases from baseline in CD4+ counts at day 28 were 216 cell/mm3 and 86 cell/mm3 in the 771-mg and 1,026-mg groups, respectively. After oral administration, median nelfinavir plasma concentrations on day 28 reached a maximum at 1 hour (2,966 ng/mL) in the 771-mg group and at 3 hours (3,157 ng/mL) in the 1,026-mg group. Data for 22 patients were included in the safety analysis; 12 patients (55%) reported at least one grade 2 or worse (moderate, severe, or very severe) adverse event. The most common grade 2 or worse adverse event was diarrhea, reported by two patients (20%) receiving 771 mg/day and seven patients (70%) receiving 1,026 mg/day; followed by nausea, flatulence, asthenia, and headache (each reported in 1 patient [10%] in the 771-mg group) and dizziness (reported in 1 patient [10%] receiving 1,026 mg/day). In the small subgroup (n = 6) who continued taking nelfinavir for longer periods (between 8 and 15 months), virologic responses were sustained in the majority of patients with good tolerability. Nelfinavir is an active HIV-protease inhibitor with favorable pharmacokinetics, good tolerability, and sustained antiviral effects. Results of this early phase I/II dose-ranging study provided data for the safety and antiretroviral activity of nelfinavir and led to the selection of higher doses for phase II/III trials to further optimize virologic and immunologic responses.
Evaluation of mebrofenin hepatoscintigraphy in neonatal-onset jaundice.
BACKGROUND: The prognosis of infants with prolonged neonatal jaundice is dependent on early diagnosis because of the need for prompt surgical management of biliary atresia. OBJECTIVE: To evaluate the usefulness of 99 mTcm-trimethylbromo-iminodiacetic acid (TBIDA, mebrofenin) in the investigation of infantile jaundice. MATERIALS AND METHODS: A retrospective study was undertaken of 58 patients with unexplained prolonged neonatal jaundice. Sixty-eight scans were reviewed. RESULTS: Mebrofenin scintigraphy confirmed the presence of a choledochal cyst in three of the four cases with that diagnosis. There were no false negative results in the nine patients with extrahepatic biliary atresia (EHBA). Three further infants had an incorrect histological diagnosis of EHBA. A gall bladder was identified by US in each case and in one of these, scintigraphy showed gut excretion. In the 16 patients with no gut excretion by 24 h, the final diagnoses were intrahepatic cholestasis (n = 7), Alagille's syndrome (n = 3), neonatal hepatitis (n = 3), alpha-1-antitrypsin deficiency (n = 2) and juvenile xanthogranuloma (n = 1). Seven infants had repeat scintigraphy after the administration of ursodeoxycholic acid (URSO). This changed five non-excretors with hepatitis into excretors. Two infants with hepatitis continued to show non-excretion after URSO, but a gallbladder was identified by US in both. CONCLUSIONS: Mebrofenin scintigraphy is accurate in confirming the presence of a choledochal cyst and in refuting the diagnosis of EHBA. While histology and scintigraphy are each 100 % sensitive for the diagnosis of EHBA, neither, individually, is accurate and the investigation of prolonged neonatal jaundice requires a multi-modality imaging strategy.
Lifesavers and Samaritans: emergency use of cellular (mobile) phones in Australia.
BACKGROUND: There has been highly publicised concern about possible radiation health effects from mobile phones and towers, but scant attention has been paid to the use of mobile phones in reducing notification times in emergencies. METHOD: National random telephone survey of Australian mobile phone users (n = 720) and extrapolation to national user population (n = 5.1 million). FINDINGS: Using a cellular phone, 1 in 8 users have reported a traffic accident; 1 in 4 a dangerous situation; 1 in 16 a non-road medical emergency; 1 in 20 a crime; and 1 in 45 being lost in the bush or being in difficulty at sea. INTERPRETATION: Any debate about the net health impact of mobile phone proliferation must balance possible negative effects (cancer, driving incidents) with the benefits from what appears to be their widespread use in rapidly reporting emergencies and in numerous acts of often health-relevant 'cellular Samaritanism'.
Specific neurochemical derangements of brain projecting neurons in apolipoprotein E-deficient mice.
Apolipoprotein E (apoE)-deficient mice provide a useful system for studying the role of apoE in neuronal maintenance and repair. Previous studies revealed specific memory impairments in these mice that are associated with presynaptic derangements in projecting forebrain cholinergic neurons. In the present study we examined whether dopaminergic, noradrenergic, and serotonergic projecting pathways of apoE-deficient mice are also affected and investigated the mechanisms that render them susceptible. The densities of nerve terminals of forebrain cholinergic projections were monitored histochemically by measurements of acetylcholinesterase activity, whereas those of the dopaminergic nigrostriatal pathway, the noradrenergic locus coeruleus cortical projection, and the raphe-cortical serotonergic tract were measured autoradiographically using radioligands that bind specifically to the respective presynaptic transporters of these neuronal tracts. The results obtained revealed that synaptic densities of cholinergic, noradrenergic, and serotonergic projections in specific brain regions of apoE-deficient mice are markedly lower than those of controls. Furthermore, the extent of presynaptic derangement within each of these tracts was found to be more pronounced the further away the nerve terminal is from its cell body. In contrast, the nerve terminal density of the dopaminergic neurons that project from the substantia nigra to the striatum was unaffected and was similar to that of the controls. The rank order of these presynaptic derangements at comparable distances from the respective cell bodies was found to be septohippocampal cholinergic > nucleus basalis cholinergic > locus coeruleus adrenergic > raphe serotonergic > nigrostriatal dopaminergic, which interestingly is similar to that observed in Alzheimer's disease. These results suggest that two complementary factors determine the susceptibility of brain projecting neurons to apoE deficiency: pathway-specific differences and the distance of the nerve terminals from their cell body.
M1 muscarinic agonist treatment reverses cognitive and cholinergic impairments of apolipoprotein E-deficient mice.
Recent studies suggest that apolipoprotein E (apoE) plays a specific role in brain cholinergic function and that the E4 allele of apoE (apoE4), a major risk factor for Alzheimer's disease (AD), may predict the extent of cholinergic dysfunction and the efficacy of cholinergic therapy in this disease. Animal model studies relevant to this hypothesis revealed that apoE-deficient (knockout) mice have working memory impairments that are associated with distinct dysfunction of basal forebrain cholinergic neurons. Cholinergic replacement therapy utilizing M1-selective muscarinic agonists has been proposed as effective treatment for AD patients. In the present study, we examined whether the memory deficits and brain cholinergic deficiency of apoE-deficient mice can be ameliorated by the M1-selective agonist 1-methylpiperidine-4-spiro-(2'-methylthiazoline), [AF150(S)]. Treatment of apoE-deficient mice with AF150(S) for 3 weeks completely abolished their working memory impairments. Furthermore, this reversal of cognitive deficit was associated with a parallel increase of histochemically determined brain choline acetyltransferase and acetylcholinesterase levels and with the recovery of these cholinergic markers back to control levels. These findings show that apoE deficiency-related cognitive and cholinergic deficits can be ameliorated by M1-selective muscarinic treatment. They also provide a novel model system for development and evaluation of therapeutic strategies directed specifically at the AD patients whose condition is attributed to the apoE genotype.
A preliminary evaluation of nelfinavir mesylate, an inhibitor of human immunodeficiency virus (HIV)-1 protease, to treat HIV infection.
A phase I/II dose-ranging open-label 28-day monotherapy study of the safety, pharmacokinetics, and antiviral activity of nelfinavir mesylate (Viracept), an inhibitor of human immunodeficiency virus (HIV)-1 protease, was done in 65 HIV-1-infected subjects. After 28 days, 54 responding subjects entered an open-label extension that allowed for the addition of nucleoside inhibitors of reverse transcriptase and dose escalation to maintain durability. The drug was well-tolerated and demonstrated robust antiviral activity, with demonstrable superiority of the 750 mg and 1000 mg three times daily regimens. Thirty subjects who continued to receive therapy at 12 months attained a persistent 1.6 log10 reduction in HIV RNA, accompanied by a mean increase in CD4 cells of 180-200/mm3. Studies of viral genotype and phenotype after virus rebound revealed that the initial active site mutation allowing for nelfinavir resistance is mediated by a unique amino acid substitution in the HIV-1 protease D30N, which does not confer in vitro phenotypic cross-resistance to the currently available protease inhibitors.
Cell-to-cell and phloem-mediated transport of potato virus X. The role of virions
Movement-deficient potato virus X (PVX) mutants tagged with the green fluorescent protein were used to investigate the role of the coat protein (CP) and triple gene block (TGB) proteins in virus movement. Mutants lacking either a functional CP or TGB were restricted to single epidermal cells. Microinjection of dextran probes into cells infected with the mutants showed that an increase in the plasmodesmal size exclusion limit was dependent on one or more of the TGB proteins and was independent of CP. Fluorescently labeled CP that was injected into epidermal cells was confined to the injected cells, showing that the CP lacks an intrinsic transport function. In additional experiments, transgenic plants expressing the PVX CP were used as rootstocks and grafted with nontransformed scions. Inoculation of the PVX CP mutants to the transgenic rootstocks resulted in cell-to-cell and systemic movement within the transgenic tissue. Translocation of the CP mutants into sink leaves of the nontransgenic scions was also observed, but infection was restricted to cells close to major veins. These results indicate that the PVX CP is transported through the phloem, unloads into the vascular tissue, and subsequently is transported between cells during the course of infection. Evidence is presented that PVX uses a novel strategy for cell-to-cell movement involving the transport of filamentous virions through plasmodesmata.
An attempt to swindle nature: press anti-immunisation reportage 1993-1997.
There is some evidence that low childhood immunisation rates in Australia may be attributed partly to parental antipathy toward immunisation. The anti-immunisation movement is becoming more organised in its efforts to lobby against childhood immunisation, while the lessening of the public's exposure to the effects of vaccine-preventable disease has provided a climate ripe for such a lobby to have a disproportionate influence on parents. Forty months of Australian print media coverage of immunisation were reviewed for anti-immunisation arguments and their underlying ideological subtexts. Of 2440 articles about childhood immunisation, 115 (4.7 per cent) contained statements opposing immunisation. Eight subtexts that referenced wider discourses about medicine, the state and the body dominated anti-immunisation discourse (cover-up; excavation of the facts; unholy alliance for profit; towards totalitarianism; us and them; vaccines as poisonous chemical cocktails; vaccines as cause of idiopathic ills; and back to nature). Attempts to redress claims made against immunisation must not only address specific claims about vaccine efficacy and safety but be grounded in a reframing of the ideological appeals that currently frame the contents of anti-immunisation discourse.
Postmodernism and public health.
Explore the source record for details and available documents.
Community panics about mobile phone towers.
Explore the source record for details and available documents.
Genotypic and phenotypic characterization of human immunodeficiency virus type 1 variants isolated from patients treated with the protease inhibitor nelfinavir.
Nelfinavir mesylate (formerly AG1343) is a potent and selective inhibitor of human immunodeficiency virus (HIV) protease approved for the treatment of individuals infected with HIV. Nucleotide sequence analysis of protease genes from plasma HIV type 1 (HIV-1) RNA revealed a unique aspartic acid (D)-to-asparagine (N) substitution at residue 30 (D30N) in 25 of 55 patients treated with nelfinavir for a median of 13 weeks. Although the appearance of D30N was occasionally associated with concurrent or sequential emergence of other changes (e.g., at residues 35, 36, 46, 71, 77, and 88), genotypic changes associated with phenotypic resistance to other protease inhibitors were not observed (e.g., at residues 48, 50, 82, and 84) or were only rarely observed (e.g., at residue 90). In phenotypic assays, viral isolates with high-level resistance to nelfinavir remained susceptible to indinavir, saquinavir, ritonavir, and amprenavir (formerly VX-478/141W94). Similar results were observed in phenotypic assays utilizing HIV-1 NL4-3, which contained the D30N substitution alone or in combination with substitutions at other residues (e.g., residues 46, 71, and 88). These data indicate that the initial pathway of resistance to nelfinavir is unique and suggest that individuals failing short courses of nelfinavir-containing regimens may respond to regimens containing other protease inhibitors.
The buried bumper syndrome: a complication of percutaneous endoscopic gastrostomy.
Explore the source record for details and available documents.
Preschool hearing, speech, language, and vision screening.
Explore the source record for details and available documents.