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Biomedical subjects

R Bradbury

Publications and source records attributed to R Bradbury.

At least 19 recordsLinked to original sources
PubMed2004

Efficacy of Piper (Piperaceae) extracts for control of common home and garden insect pests.

Extracts from three species of the plant family Piperaceae, Piper nigrum [L.], Piper guineense [Schum & Thonn, and Piper tuberculatum [Jacq.], were tested for efficacy against insects from five orders. All three species contain isobutyl amides, plant secondary compounds that act as neurotoxins in insects. These materials are considered safe to mammals because Piper spp. were used for centuries for spice and medicinal purposes. When 24-h P. nigrum LC50 values were compared between common insect pests from eastern Canada and the northeastern United States, the most sensitive species in order of increasing lethal concentration were eastern tent caterpillar, Malacosoma americanum (F.) < European pine sawfly larvae, Neodiprion sertifer (Geoffroy) < spindle ermine moth larvae, Yponomeuta cagnagella [Hübner] < viburnum leaf beetle larvae, Pyrrhalta viburni [Paykull] < stripped cucumber beetle adults, Acalymma vittatum (F.) < Colorado potato beetle adults, Leptinotarsa decemlineata (Say) < Japanese beetle adults, Popillia japonica [Newman] < hairy chinch bug, Blissus leucopterus hirtis [Montandon]. The life stage tested was the point at which each species causes the greatest amount of damage to the host plant and the point at which most gardeners would likely choose to treat with a conventional synthetic insecticide. Greenhouse trials revealed that the pepper formulations also had a repellent activity, thus protecting plant leaves from 1) herbivory (lily leaf beetle, Lilioceris lilii [Scopoli], adults and larvae and stripped cucumber beetle adults) and 2) oviposition [European corn borer, Ostrinia nubilalis (Hübner)]. Combinations with other botanical extracts were additive at best in toxicity and repellent trials. Nontarget toxicity to beneficial invertebrates is a possibility because the P. nigrum LC50 for beneficial ladybird beetles was 0.2%. P. nigrum extracts can provide a reasonable level of control against lepidopteran and European pine sawfly larvae and also will work as a short-term repellent and feeding deterrent. It is recommended that the use of Piper extracts be restricted to small-scale spot treatments in residential areas where insect pest outbreaks have occurred.

Animals↗
PubMed2001

Studies on [3H]CP-55940 binding in the human central nervous system: regional specific changes in density of cannabinoid-1 receptors associated with schizophrenia and cannabis use.

A number of studies suggested that cannabis use can cause or exacerbate psychoses and may increase the risk of developing schizophrenia. These findings suggest that changes in the cannabinoid system of the brain may be involved in the pathology of schizophrenia. To determine whether changes in the cannabinoid system were present in the brains of subjects with schizophrenia, we used in situ radioligand binding and autoradiography to measure the binding of [3H]CP-55940 to the cannabinoid-1 receptor in the dorsolateral prefrontal cortex (Brodmann's area 9), caudate-putamen and areas of the temporal lobe from schizophrenic and control subjects, some of whom had ingested cannabis close to death. There was an increase in the density of [3H]CP-55940 binding to cannabinoid-1 receptors in the dorsolateral prefrontal cortex from subjects with schizophrenia (mean+/-S.E.M.: 142+/-9.9 vs 119+/-6.6fmol/mg estimated tissue equivalents; P<0.05) that was independent of recent cannabis ingestion. There was an increase in the density of cannabinoid-1 receptors in the caudate-putamen from subjects who had recently ingested cannabis (151+/-9.0 vs 123+/-7.2fmol/mg estimated tissue equivalents; P<0.05) that was independent of diagnoses. These data indicate that there are changes in cannabinoid-1 receptors in the dorsolateral prefrontal cortex that may prove to be associated with the pathology of schizophrenia. By contrast, changes in the density of cannabinoid-1 receptors may occur in the caudate-putamen in response to cannabis ingestion.

Brain↗
PubMed2000

New chromogenic identification and detection of Staphylococcus aureus and methicillin-resistant S. aureus.

This paper describes a new chromogenic plate medium, CHROMagar Staph aureus (CHROMagar, Paris, France), for the identification of Staphylococcus aureus on the basis of colony pigmentation. The abilities of CHROMagar Staph aureus, thermostable nuclease (DNase), and mannitol salt agar (MSA) to identify S. aureus isolates (n = 114) and discriminate between S. aureus and coagulase-negative staphylococci (CoNS; n = 22) were compared. CHROMagar Staph aureus proved to be more sensitive and specific than DNase and MSA, allowing a reliable, simple, and rapid method for the identification of S. aureus isolates. All CoNS encountered in this study with the exception of S. chromogenes could be easily differentiated from S. aureus on this medium. The supplementation with 4 microgram of oxacillin or methicillin per ml allowed simple identification of methicillin resistance in hospital-acquired S. aureus strains which show multiple-drug resistance profiles. Community-acquired methicillin-resistant S. aureus strains showing non-multi-drug resistance profiles require further evaluation on this new chromogenic medium. Methicillin or oxacillin resistance of all S. aureus isolates was confirmed by the detection of penicillin-binding protein 2a, encoded by the mecA gene, using the latex slide agglutination MRSA-Screen test (PBP 2' Test, DR900M; Oxoid).

Bacterial Proteins↗
PubMed1999

Modification of gene expression by dietary antioxidants in radiation-induced apoptosis of mice splenocytes.

The modification of radiation-induced apoptosis in splenocytes by a vitamin-containing dietary supplement was studied. For 45 days prior to irradiation at a lethal dose of 6 Gy, mice received a dietary supplement containing vitamins with antioxidant properties and microelements. The expression of TRPM-2 (a marker for programmed cell death), bcl-2 (the product of which has been shown to prevent apoptosis), superoxide dismutase, and catalase genes was studied at different time intervals after irradiation. Radiation-induced alterations in gene expression were different in the control and the antioxidant mixture-fed mice. The antioxidant mixture administration resulted in an inhibition of TRPM-2 expression both before and after irradiation. The bcl-2 mRNA content steadily increased after irradiation in splenocytes from antioxidant mixture-fed mice, while in the control group 2-h after irradiation only trace amount of bcl-2 mRNA was detected. In splenocytes from control mice, the expression of superoxide dismutase and catalase genes significantly decreased within 2-h after irradiation; whereas in mice receiving the antioxidant mixture, inhibition of catalase gene expression was not as prominent. The expression of superoxide dismutase gene was still high 24-h after irradiation. The antioxidant administration decreased the radiation-induced apoptosis and delayed internucleosomal fragmentation of DNA. Our data suggest that radiation-induced alteration of gene expression is, at least in part, determined by reactive oxygen species.

Animals↗
PubMed1999

Expression of the human P2Y6 nucleotide receptor in normal placenta and gestational trophoblastic disease.

The P2Y family of purinergic receptors are members of the G-protein-coupled receptor superfamily. The P2Y6 subtype is expressed at particularly high levels in the placenta, suggesting that P2Y6 plays an important role in placental function. However, the cellular localization of P2Y6 within the placenta is unknown. This study examined the expression of P2Y6 in first-trimester and full-term placental tissues, as well as examples of gestational trophoblastic disease, by Northern blot analysis and in situ hybridization. P2Y6 message was present at similar levels in first-trimester and full-term placenta, and in situ hybridization revealed that message was most abundant in the cytotrophoblast of the villi and chorionic plate at both gestational stages. The syncytiotrophoblast harbored lower levels of P2Y6 in first-trimester placenta, and by full-term, the syncytiotrophoblast only focally expressed P2Y6 transcripts. Neither the intermediate trophoblast nor nontrophoblastic elements of the placenta expressed P2Y6. Molar disease expressed P2Y6 in the villous trophoblast but not in the proliferative intermediate trophoblast, recapitulating the pattern of first-trimester placenta. Neither choriocarcinoma nor the choriocarcinoma cell lines JEG-3 and JAr expressed P2Y6 transcript. These findings reveal that P2Y6 mRNA production is highly characteristic of the epithelial-like cytotrophoblast and syncytiotrophoblast, whereas expression is absent in the mesenchymal-like intermediate trophoblast. Thus, P2Y6 may play an important role in trophoblastic development, differentiation, and neoplasia.

Blotting, Northern↗
PubMed1998

Clozapine and olanzapine treatment decreases rat cortical and limbic GABA(A) receptors.

The density of GABA(A) receptors in the hippocampus and the temporal cortex from rats treated for 28 days with either haloperidol, chlorpromazine, clozapine or olanzapine was measured. Compared to haloperidol (0.01 and 0.1 mg kg(-1) day(-1)) and chlorpromazine (0.1 and 1 mg kg(-1) day(-1)), clozapine and olanzapine (0.1 and 1 mg kg(-1) day(-1)) markedly decreased the density of GABA(A) receptors in these two brain regions. These data suggest that modulation of GABAergic transmission could be an important action of some antipsychotic drugs.

Animals↗
PubMed1998

Candidaemia in an Australian teaching hospital: relationship to central line and TPN use.

We performed a retrospective review of patient case records to identify risk factors for candidaemia and to assess incidence, management and outcome of candidaemia in an Australian teaching hospital. Between January 1994 and June 1996, 38 cases of candidaemia were identified. The incidence was 0.74 per 1000 admissions of 24 h duration, and 1.54 per 1000 admissions of 5 days or more. The mortality rate was 34%, with eight of 13 (62%) of these deaths attributable to candidaemia. Risk factors included underlying gastrointestinal disease (66%) and recent abdominal surgery (61%), while recent broad spectrum antibiotic use was a contributing factor in 95%. Twenty-nine patients (76%) had a vascular access device in situ at time of detection. This was the apparent source of candidaemia in 28 (97%). Twenty-six (90%) were being used for TPN administration. Of patients receiving TPN, 5.2% developed candidaemia. Standard central venous catheters (CVC) were present in 21 patients (55%), having been in situ for an average of 12.7 days. Eighteen (86%) had been in situ for 7 days or more. Management involved removal of any implicated intravascular device. Thirty of 33 early survivors received antifungal chemotherapy. Therapy with amphotericin B, fluconazole alone or amphotericin B followed by fluconazole was equally effective. Concurrent corticosteroid use and neutropaenia contributed to increased mortality. Candidaemia is not benign. Policies regarding regular changing of central lines, especially in the setting of TPN administration and control of broad spectrum antibiotic use are appropriate measures aimed to reduce incidence. Management involves removal of implicated lines and antifungal chemotherapy. Pre-emptive therapy for candida infection should be considered in selected patients with the likelihood of TPN-related central line sepsis. Fluconazole is an effective alternative to amphotericin B in non-neutropenic patients.

Adult↗
PubMed1998

Prevalence and demographic determinants of metronidazole resistance by Helicobacter pylori in a large cosmopolitan cohort of Australian dyspeptic patients.

BACKGROUND: The pre-treatment sensitivity of Helicobacter pylori to metronidazole is a key determinant of successful eradication therapy and should influence local choice of therapy. However, there are few data defining the prevalence of metronidazole resistance (MR) in Australia. AIM: To determine prospectively the prevalence and demographic determinants of MR in H. pylori isolates from a large and cosmopolitan cohort of dyspeptic patients in Sydney. METHODS: Consecutive dyspeptic patients undergoing endoscopy had gastric biopsies for histology, urease test and culture. Metronidazole resistance was determined by E-test after subculture. An MIC > 8 micrograms/mL defined MR. Patient age, gender, birthplace and history of previous nitroimidazole use were recorded. RESULTS: In 732 patients, H. pylori was present in 46.4%. Culture was successful in 81% and subculture for MR in 88% of these. In 237 evaluable patients the overall MR rate was 59.1%. Five patients had had prior triple therapy for H. pylori (of which four of five had MR). Therefore, the primary MR rate in the study population was 58.6% (136/232). MR was more prevalent in younger patients (p = 0.0002). The MR rate was 70.4% in patients 18-39 years, 66.7% in those aged 40-59 years and lowest (38.9%) in those 60 years or older (p = 0.002). The MR rate was highest in patients born in Southeast Asia (72.8%, 59/81) and significantly higher than in Australian born (48.1%, 26/54), or Southern European (46.2%, 24/52) born patients (p = 0.002). There was no gender difference. Logistic regression to determine the impact of each variable (birthplace, age and gender) on MR identified Southeast Asia birthplace as a factor associated with greater likelihood of harbouring an MR isolate (OR 1.88, p = 0.02). Southern European born patients had the lowest risk of MR (OR 0.70, p = 0.02) as did patients older than 60 years (OR 0.56, p = 0.04). A definite history of prior metronidazole use was infrequent and not predictive of MR. CONCLUSIONS: While a high rate of MR is not unexpected in patients born in developing countries, the high rate in Australian born patients is surprising and of concern. This may relate to the high local usage of nitroimidazoles as monotherapy and has important implications for the effectiveness of metronidazole containing triple therapies.

Adolescent↗
PubMed1998

Staphylococcal bacteraemia: the hospital or the home? A review of Staphylococcus aureus bacteraemia at Concord Hospital in 1993.

AIMS: To examine the risk factors for, and the complications and mortality of, Staphylococcus aureus bacteraemia. METHODS: A retrospective case review of patients with S. aureus bacteraemia in 1993 diagnosed at the Concord Repatriation General Hospital, Sydney. RESULTS: Of 104 cases reviewed, 32 were due to methicillin resistant S. aureus (MRSA), 73 were due to methicillin sensitive S. aureus (MSSA) and one was a dual infection. Twenty-eight of the bacteraemias were community-acquired, including one case of MRSA, and 76 were hospital-acquired; 38% had an implanted prosthetic device or graft. The average age (68 years), incidence of underlying diseases and hospitalisation in the past month (26%) did not differ between MRSA and MSSA groups. MRSA was more likely in patients with recent broad-spectrum antibiotic use (53% vs 0, p < .01). Vascular access was the commonest source of sepsis (61%) but in community-acquired cases the source was unknown in 50%. Use of central line access was more predictive of MRSA infection (75% vs 49%, p = .018). In hospital-acquired infection, MRSA sepsis occurred later in the course of the admission (26 days vs eight days, p < .01). Directly attributable mortality was highest in MRSA and community-acquired MSSA infection (9% and 11%) compared with hospital-acquired MSSA infection (1%). CONCLUSIONS: Nosocomial S. aureus bacteraemia, particularly MRSA, is a major source of preventable morbidity, which could be addressed by improved infection control of MRSA, antibiotic use and attention to central line catheter use.

Aged↗
PubMed1997

A prospective study of Clostridium difficile infection and colonization in pediatric oncology patients.

BACKGROUND: Patients with cancer often receive broad spectrum antibiotics in addition to antineoplastic chemotherapy. Both treatments predispose adult oncology patients to infection and colonization with Clostridium difficile, but the role of this pathogen in pediatric oncology patients is poorly defined. METHODS: A prospective study of 149 fecal samples from symptomatic pediatric oncology patients and 58 samples from asymptomatic patients was performed. Each sample was analyzed for the presence of C. difficile and its toxins A and B. RESULTS: In 8.7% of the symptomatic samples and 19% of the asymptomatic samples toxigenic C. difficile was found. No association was found between either the use of antibiotics and/or the administration of chemotherapy and the presence of toxigenic C. difficile. Younger children were more likely to be infected or colonized with C. difficile, and there was no evidence of nosocomial transmission of C. difficile within the study population. CONCLUSIONS: As toxigenic C. difficile may form part of the normal flora in young children, this study indicates that in the absence of a defined outbreak, C. difficile does not appear to be an important pathogen in pediatric oncology patients.

Adolescent↗
PubMed1996

Media coverage of the Child B case.

The case of a girl with leukaemia, known as Child B, hit the headlines in March 1995 when her father refused to accept the advice of doctors who counselled against further treatment and took Cambridge and Huntingdon Health Authority to court for refusing to fund chemotherapy and a second bone transplant for her in the private sector. British national newspapers varied greatly in the way they covered the case. Some paid little attention to clinical considerations and presented the case as an example of rationing based on financial considerations. Their selective presentations meant that anyone reading just one newspaper would have received only limited and partial information. If members of the public are to participate in debates about treatment decisions and health care rationing, means other than the media will need to be found to inform and involve them.

Attitude to Health↗