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Biomedical subjects

P Mann

Publications and source records attributed to P Mann.

At least 19 recordsLinked to original sources
PubMed2006

Identification of heavy metal-induced genes encoding glutathione S-transferases in the arbuscular mycorrhizal fungus Glomus intraradices.

Arbuscular mycorrhizal fungi are able to alleviate the stress for plants caused by heavy metal contamination of soil. To analyze the molecular response of arbuscular mycorrhizal fungi to these pollutants, a subtractive cDNA library was constructed using RNA from Glomus intraradices extraradical hyphae of a root organ culture treated with a mixture of Cd, Zn, and Cu. Screening by reverse Northern blot analysis indicated that, among 308 clones, 17% correspond to genes up-regulated by heavy metals. Sequence analysis of part of the clones resulted, amongst others, in the identification of six genes putatively coding for glutathione S-transferases belonging to two different classes of these enzymes. Expression analyses indicated that the genes are differentially expressed during fungal development and that their RNA accumulation dramatically increases in extraradical hyphae grown in a heavy metal-containing solution.

Daucus carota↗
PubMed2005

Differential regulation of hyaluronic acid synthase isoforms in human saphenous vein smooth muscle cells: possible implications for vein graft stenosis.

Autologous saphenous vein bypass grafts (SVG) are frequently compromised by neointimal thickening and subsequent atherosclerosis eventually leading to graft failure. Hyaluronic acid (HA) generated by smooth muscle cells (SMC) is thought to augment the progression of atherosclerosis. The aim of the present study was (1) to investigate HA accumulation in native and explanted arterialized SVG, (2) to identify factors that regulate HA synthase (HAS) expression and HA synthesis, and (3) to study the function of the HAS2 isoform. In native SVG, expression of all 3 HAS isoforms was detected by RT-PCR. Histochemistry revealed that native and arterialized human saphenous vein segments were characterized by marked deposition of HA in association with SMC. Interestingly, in contrast to native SVG, cyclooxygenase (COX)-2 expression by SMC and macrophages was detected only in arterialized SVG. In vitro in human venous SMC HAS isoforms were found to be differentially regulated. HAS2, HAS1, and HA synthesis were strongly induced by vasodilatory prostaglandins via Gs-coupled prostaglandin receptors. In addition, thrombin induced HAS2 via activation of PAR1 and interleukin 1beta was the only factor that induced HAS3. By small interfering RNA against HAS2, it was shown that HAS2 mediated HA synthesis is critically involved in cell cycle progression through G1/S phase and SMC proliferation. In conclusion, the present study shows that HA-rich extracellular matrix is maintained after arterialization of vein grafts and might contribute to graft failure because of its proproliferative function in venous SMC. Furthermore, COX-2-dependent prostaglandins may play a key role in the regulation of HA synthesis in arterialized vein grafts.

Adult↗
PubMed2004

Growth-inhibitory and cell cycle-arresting properties of the rice bran constituent tricin in human-derived breast cancer cells in vitro and in nude mice in vivo.

Tricin, a flavone found in rice bran, inhibits the growth of human-derived malignant MDA-MB-468 breast tumour cells at submicromolar concentrations. As part of the exploration of tricin as a potential cancer chemopreventive agent, we investigated the duration and cell cycle specificity of growth inhibition elicited by tricin in vitro and the effect of tricin on the development of MDA-MB-468 tumours grown in immune-compromised MF-1 mice in vivo. Preincubation of MDA-MB-468 cells with tricin (1-40 microM) for 72 h compromised cell growth after tricin removal, and such irreversibility was not observed in human breast-derived nonmalignant HBL-100 cells. Tricin (>/=5 microM) arrested MDA-MB-468 cells in the G2/M phase of the cell cycle without inducing apoptosis as adjudged by annexin V staining. In nude mice consumption of tricin with the diet (0.2%, w w(-1)) from 1 week prior to MDA-MB-468 cell implantation failed to impede tumour development. Steady-state levels of tricin in plasma, breast tumour tissue and intestinal mucosa, as measured by HPLC, were 0.13 microM and 0.11 and 63 nmol g(-1), respectively. Cells were exposed to tricin (0.11, 1.1 or 11 microM) in vitro for 72 h and then implanted into mice. The volume of tumours in animals bearing cells pre-exposed to 11 microM tricin was less than a third of that in mice with control cells, while tumours from cells incubated with 0.1 or 1.1 microM tricin were indistinguishable from controls. These results suggest that the potent breast tumour cell growth-inhibitory activity of tricin in vitro does not directly translate into activity in the nude mouse bearing the MDA MB-468 tumour. While the results do not support the notion that tricin is a promising candidate for breast cancer chemoprevention, its high levels in the gastrointestinal tract after dietary intake render exploration of its ability to prevent colorectal carcinogenesis propitious.

Administration, Oral↗
PubMed2004

The triple A syndrome is due to mutations in ALADIN, a novel member of the nuclear pore complex.

The triple A syndrome (MIM#231550) is a rare autosomal recessive disorder characterized by adrenocorticotropic hormone (ACTH) resistant adrenal failure, achalasia, alacrima, and a variety of neurological and dermatological features. The triple A syndrome is caused by mutations in the AAAS gene, which encodes a protein known as ALADIN (ALacrima Achalasia aDrenal Insufficiency Neurologic disorder). ALADIN is a new WD-repeat protein that has no significant homology to any previously identified WD-repeat protein. It has been shown that it colocalizes with nuclear pore complexes (NPCs), a finding that strongly suggests an involvement of ALADIN in nucleocytoplasmic transport. An investigation of 110 families with triple A syndrome disclosed mutation hot spots including Q15K (exon 1), and S293P (exon 8), which occur in 17 and 21 families from different geographical regions, respectively. The variable phenotype of all patients cannot be correlated with the localization and the nature of the ALADIN mutations. Thus, modifying genes/factors may be involved in the progression of this neurodegenerative disease. The lack of AAAS mutations in eight patients and negative linkage to chromosome 12q13 in three families are suggestive of genetic heterogeneity. To examine the cellular localization of ALADIN mutants causing triple A syndrome, we investigated nine different ALADIN-mutants: 2 nonsense (W84X, Q456X), 2 frameshift (F157fsX171, G397fsX414) and 5 point mutations (Q15K, L25P, H160R, S263P, L381R) by transfection experiments with green fluorescence protein. Mutants were predominantly localized in the cytoplasm, but also found in the nucleus indicating that ALADIN is essential for NPC targeting. To investigate physiological functions of ALADIN in vivo, we generated and analysed Aaas-/- knockout mice by homologous recombination in embryonic stem cells. Surprisingly, required animals lack any gross abnormality in adrenal and nervous system function. Further studies have to investigate the role of ALADIN at NPCs and to identify interacting proteins. Functional analyses of ALADIN may permit further understanding of its role for adrenocortical function and neurodevelopment.

Adrenal Gland Diseases↗
PubMed2003

From trench fever to endocarditis.

The case of a 44 year old woman with infective endocarditis due to Bartonella quintana, an organism long recognised to cause a condition known as trench fever, is reported. This case illustrates the lengthy differential diagnosis of "culture negative" endocarditis. In addition the presence of serological cross reactivity of Bartonella spp and Chlamydia spp demonstrates the potential for misdiagnosis in these circumstances.

Adult↗
PubMed2002

Differential RNA accumulation of two beta-tubulin genes in arbuscular mycorrhizal fungi.

RNA was isolated from spores of different arbuscular mycorrhizal (AM) fungi and used for RT-PCR with degenerate primers for beta-tubulin genes. PCR products were cloned and the sequence of several clones was analysed for each fragment. Comparison of sequences identified two loci for beta-tubulin genes with different GC content and codon usage. Btub1 sequences were most similar to beta-tubulin genes from the Oomycota, while Btub2 sequences showed highest similarity to sequences from the Zygomycota. RT-PCR experiments were carried out to monitor RNA accumulation patterns of Btub1 and Btub2 in asymbiotic germinating spores and in symbiotic extraradical hyphae of three different AM fungi. This indicated that Btub1 is constitutively expressed in Gigaspora rosea, but down-regulated during symbiosis in Glomus mosseae and Glomus intraradices. In contrast, Btub2 showed constitutive expression in the two Glomus species, but down-regulation in G. rosea. Further analysis of different fungi indicated that Btub2 primers could be used to specifically monitor RNA accumulation of AM fungi in environmental samples.

Founder Effect↗
PubMed2001

Mobile lipid production after confluence and pH stress in perfused C6 cells.

NMR-visible mobile lipid (ML) has been observed in aggressive tumors and also in in vitro tumor cell models subjected to growth-inhibiting conditions, such as confluence or low-pH stress. The aim of the present study was to determine if ML production after confluence or low pH stress in a cultured cell model of brain tumor is due to growth arrest alone. ML was observed in situ by one- and two-dimensional (1)H NMR in viable but growth-arrested C6 glioma cells superfused for a period of 48 h after harvesting. The rate of ML production in cells harvested at subconfluence was compared to the rate in cells confluent for one cell cycle and to the rate in subconfluent-harvested cells superfused at low pH (pH 6.1). Confluent-harvested cells produced ML at a markedly greater rate than that of cells harvested at subconfluence, suggesting the involvement of prior cell-cell contact rather than simple growth arrest. A high rate was also observed in subconfluent-harvested cells subjected to low pH, indicating that ML in pH-stressed cells also does not arise from growth arrest alone. Furthermore, two-dimensional data on the degree of unsaturation of the ML fatty acyl chains and one-dimensional (31)P and two-dimensional (1)H NMR data on the GPC content of the cells suggest distinct metabolic pathways for the production of ML following confluence and low-pH stress.

Adenosine Triphosphate↗
PubMed2001

The influence of growth hormone replacement on heart rate variability in adults with growth hormone deficiency.

OBJECTIVE: Growth hormone (GH) deficiency is associated with increased cardiovascular morbidity and mortality. Abnormalities in heart rate variability (HRV), a surrogate marker of cardiac autonomic tone, have also been found in untreated growth hormone deficient (GHD) patients. Similar abnormalities have been found in patients with complications postmyocardial infarction. DESIGN AND MEASUREMENTS: This study was designed to investigate whether GH treatment leads to normalization of cardiac autonomic tone. HRV measurements were obtained from 15 minute resting ECG recordings in 11 untreated adult GHD patients (7 females; mean age 39.2 years), 10 GHD patients (6 females; mean age 46.2 years) reCENving GH replacement (mean duration, 52.7 months) and 12 healthy controls (7 females; mean age 44.6 +/- 2.9 years) who were all of similar age, weight and BMI. The untreated GHD patients were then commenced on GH and HRV measurements repeated after 3 and 6 months of treatment. RESULTS: In accord with our previous findings, HRV analysis using Fast Fourier Transform (FFT) showed a distinct pattern of abnormality in GHD patients compared with controls. Specifically, there was an increase in nHF power (P = 0.04) and a reduction in nLF power (P = 0.04) (representing parasympathetic and sympathetic activity, respectively), a reduction in nVLF power (P = 0.03) and a 50% reduction in LF/HF ratio (P = 0.02) (a measure of sympathovagal balance) in GHD patients when compared with controls. HRV results in patients who have been on long-term GH replacement were indistinguishable from controls. After 3 months GH replacement in the untreated GHD patient group, nVLF power had increased by 28% (P = 0.03) at 3 months and this was sustained at 6 months. However, no significant changes in LF and HF power were seen. CONCLUSIONS: These results suggest that abnormalities of the cardiac autonomic system in GHD patients may be correctable. Longer duration of prospective follow-up will be required to determine at what time point improvements in the other frequency bands occur.

Adult↗
PubMed2000

Interlaboratory comparison of the CB6F1-Tg rasH2 rapid carcinogenicity testing model.

Several genetically engineered mouse models are currently being examined for potential use in cancer hazard identification. We have undertaken an interlaboratory comparison of the performance of the CB6F1-Tg rasH2 transgenic mouse in cancer bioassays concurrently conducted in the United States and Japan. Chemicals selected for study included known human carcinogens (melphalan and cyclosporin A) and known rodent carcinogens (p-cresidine and vinyl carbamate) tested at carcinogenic doses, and non-carcinogens (p-anisidine and resorcinol) tested at appropriate high doses. Because of abdominal adhesions caused by the intraperitoneal dosing vehicle, melphalan was excluded from the study results. The remaining five studies showed similar results between the two laboratories conducting each study. Vinyl carbamate gave the strongest positive response inducing lung adenomas and carcinomas and splenic hemangiosarcomas. p-Cresidine was considered positive for urinary bladder transitional neoplasia. Cyclosporin A, p-anisidine, and resorcinol were negative in all studies. Although only five chemicals were successfully tested in this interlaboratory comparison, there was good concordance in outcome for the strong carcinogens and for the non-carcinogens. Successful testing of chemicals with less carcinogenic potential may require modifications in study design to include more animals and longer study duration.

Adenoma↗
PubMed2000

Abnormal heart rate variability in adults with growth hormone deficiency.

GH-deficient (GHD) patients have increased risk of cardiovascular death and may have cardiac structural abnormalities. In non-GHD patients these are associated with cardiac autonomic dysfunction, and it is possible that autonomic dysfunction is also present in GHD patients. Power spectral analysis (PSA) of heart rate variability (HRV) indirectly measures cardiac autonomic tone and generates peaks at 3 frequency bands, very low frequency (VLF), low frequency (LF) and high frequency (HF). The area under the LF curve is considered to reflect predominantly cardiac sympathetic activity, whereas HF indicates parasympathetic activity. PSA of HRV was performed in 14 normotensive GHD patients (5 men and 9 women; mean age, 35.2 yr) and 19 healthy controls (9 men and 10 women; mean age, 38.3 yr). GHD patients had 26% lower normalized LF power (P < 0.004), 39% higher normalized HF power (P < 0.001), 28% lower normalized VLF power (P < 0.046), and 51% lower LF/HF ratio (an index of sympathovagal balance; P < 0.001) compared to controls. These data indicate that heart rate variability is abnormal in patients with GHD. The decreased sympathetic tone could be a consequence of reduced central sympathetic tone or altered cardiac responsiveness to autonomic control and may contribute to the increased cardiovascular risk in GHD patients.

Adult↗
PubMed1998

A study of imidazole-based nuclear magnetic resonance probes of cellular pH.

A number of imidazole-based compounds were tested for their utility as (1)H NMR molecular probes of intracellular pH. Imidazole, previously found useful as a probe of erythrocyte pH, reported a pH in perfused canine glioma cells that was more than 1 pH unit lower than that reported by inorganic phosphate, consistent with the known lysosomal compartmentation of the molecule. Imidazole acetate, also proposed as an NMR probe of cellular pH, was found not to enter the cells of this study. Histidine was found to be readily taken up by cells and reported a pH consistent with that reported by inorganic phosphate. Using the chemical shift of the histidine H2 proton in cells incubated with 10 mM histidine, cellular pH measurements could be obtained in less than 1 s. This compares quite favorably with the measurement time, typically several minutes, needed to assess in vivo pH by (31)P NMR. The use of histidine as a probe of pH is demonstrated in perfused canine and rat glioma cells subjected to ischemia or to low extracellular pH.

Animals↗
PubMed1997

In utero exposure to low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin alters reproductive development of female Long Evans hooded rat offspring.

Prenatal administration of a single dose of 1 microg TCDD/kg induces malformations of the external genitalia and subfertility in female offspring (L. E. Gray, Jr., and J. S. Ostby (1995) Toxicol. Appl. Pharmacol. 133, 285-294). A cross-fostering study indicated that in utero but not lactational TCDD exposure (1 microg TCDD/kg on gestational Day 15) induces cleft phallus, vaginal thread formation, and reduced ovarian weight. TCDD treatment on the 15th day of pregnancy at 0, 0.05, 0.20, or 0.80 microg TCDD/kg delayed vaginal opening at 0.80 microg/kg in the progeny. A persistent vaginal thread was displayed by 27% of the progeny at 0.20 and 92% at 0.80 microg TCDD/kg. These effects did not appear to result from abnormal ovarian function during prepubertal development; neither serum estradiol levels nor ovarian estradiol production were reduced in 21- or 28-day-old progeny of dams exposed to 1 microg TCDD/kg. In addition, partial to complete clefting of the phallus was displayed in TCDD-treated rats (10% at 0.20 and 60% at 0.80 microg TCDD/kg) and these dosage levels also increased the length of the urethral slit, increased distance from the urethral opening to the tip of the phallus, and decreased distance from the urethral opening to the vaginal orifice. Although fertility rates were normal, time-to-pregnancy was delayed by treatment with 0.80 microg TCDD/kg. When necropsied at 20 months of age, females from the TCDD-dose groups displayed histopathological alterations of the reproductive tract. In summary, administration of TCDD at dosage levels of 0.2, 0.8, and 1.0 microg/kg produces morphological reproductive alterations in female rat offspring as a consequence of in utero exposure.

Abnormalities, Drug-Induced↗
PubMed1997

Pneumococcal pericarditis presenting as an out of hospital cardiopulmonary arrest.

Serious complications of pneumococcal pneumonia have become uncommon with effective antibiotic treatment. Purulent pericarditis is a rare though well described complication of untreated pneumococcal sepsis. A case of untreated pneumococcal pneumonia complicated by purulent pericarditis is described. This presented as an out of hospital asystolic cardiopulmonary arrest.

Adult↗
PubMed1997

Role perceptions of mothers with young children: the impact of a child's disability.

OBJECTIVE: The purpose of this study was to examine and compare the perceived past, present, and future occupational roles of mothers of young children. Awareness of the role demands placed on mothers will assist occupational therapists in addressing the needs of children with disabilities within the family context. METHOD: One hundred and thirty-five mothers of children 6 months to 5 years of age completed the Role Checklist, which examines participants' perceptions of past, present, and future occupational roles. Forty-five participants had children with multiple disabilities and major functional limitations, 45 had children with Down's syndrome, and 45 had children who were typically developing. RESULTS: The group of mothers of children who were typically developing was found to have significantly more present roles than the other two groups. All three groups lost significant numbers of roles from past (before birth of child) to present and anticipated adding significant numbers of future roles. There were no significant differences among the three groups in value placed on occupational roles. CONCLUSION: Role demands of caring for a young child were high for all participants, particularly if the child had a disability. Participants seemed to respond to these demands by giving up other discretionary roles in order to meet their caregiving obligations. Thus, asking mothers of children with disabilities to take on therapy-related caregiving tasks may contribute to role strain.

Adult↗
PubMed1996

Effect of postoperative mydriatics on the iris.

PURPOSE: To assess the role postoperative mydriatics play after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (IOL) implantation in causing iris modifications and in controlling inflammation. SETTING: Outpatients Department, Ninewells Hospital, Dundee, Scotland. METHODS: The prospective study comprised 136 patients who had standardized ECCE. Half the patients used a mydriatic for 2 weeks postoperatively. Anterior chamber activity, pain, and eye redness were evaluated at 2 weeks postoperatively; pupil shape, peripheral anterior synechias, IOL position, and iris adhesions, at 6 weeks. RESULTS: Iris-lens adhesions were significantly more common in the group using a mydriatic. There was no difference between the two groups in postoperative inflammation. CONCLUSION: Mydriatics should not be used routinely after ECCE with posterior chamber IOL implantation.

Aged↗