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P H Smith

Publications and source records attributed to P H Smith.

At least 19 recordsLinked to original sources
PubMed2004

Atmospheric imaging results from the Mars exploration rovers: Spirit and Opportunity.

A visible atmospheric optical depth of 0.9 was measured by the Spirit rover at Gusev crater and by the Opportunity rover at Meridiani Planum. Optical depth decreased by about 0.6 to 0.7% per sol through both 90-sol primary missions. The vertical distribution of atmospheric dust at Gusev crater was consistent with uniform mixing, with a measured scale height of 11.56 +/- 0.62 kilometers. The dust's cross section weighted mean radius was 1.47 +/- 0.21 micrometers (mm) at Gusev and 1.52 +/- 0.18 mm at Meridiani. Comparison of visible optical depths with 9-mm optical depths shows a visible-to-infrared optical depth ratio of 2.0 +/- 0.2 for comparison with previous monitoring of infrared optical depths.

Algorithms↗
PubMed2004

Evidence from Opportunity's Microscopic Imager for water on Meridiani Planum.

The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.

Extraterrestrial Environment↗
PubMed2004

Textures of the soils and rocks at Gusev Crater from Spirit's Microscopic Imager.

The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous textures and evidence for alteration rinds, coatings, and veins consistent with secondary mineralization. The rock textures are consistent with a volcanic origin and subsequent alteration and/or weathering by impact events, wind, and possibly water.

Extraterrestrial Environment↗
PubMed2004

The genetics of non-host disease resistance in wheat to barley yellow rust.

Non-host resistance is investigated as a potential source of durable resistance. However, the genetics of non-host resistance between closely related plant species and their corresponding pathogens would indicate that in these interactions, non-host resistance primarily involves major genes that operate on a gene-for-gene principal similar to that seen in host resistance. Wheat is a non-host of the barley-attacking form of the fungus responsible for yellow rust, i.e. Puccinia striiformis f. sp. hordei. While P. striiformis f. sp. hordei is generally unable to infect wheat, a partial susceptibility was exhibited by the wheat variety Chinese 166. Consequently, in the cross Lemhi x Chinese 166 two major QTLs for resistance to P. striiformis f. sp. hordei were identified: one on chromosome 1D and a second on 2B. These two QTLs accounted for 43.5% and 33.2% of the phenotypic variance for resistance to barley yellow rust, respectively. In addition, two QTLs of smaller effect were also identified: one on chromosome 5A, contributing 5.1% of the variance and a second on chromosome 6A, contributing 10.9% to the phenotype. The QTL on 6A was derived from the susceptible variety, Chinese 166. In all cases the resistance towards P. striiformis f. sp. hordei was associated with a visual chlorosis/necrosis response typical of race-specific host resistance.

Basidiomycota↗
PubMed2004

A genetic analysis of adult plant resistance to stripe rust in the wheat cultivar Kariega.

The wheat cultivar Kariega expresses complete adult plant resistance to stripe rust in South Africa. The aim of this investigation was to determine the extent and nature of variability in stripe rust resistance in a population of 150 doubled haploid lines generated from a cross between Kariega and the susceptible cultivar Avocet S. Analysis of field data for adult plant stripe rust resistance identified two major QTLs and two minor QTLs in the resistant cultivar Kariega. The two major QTLs were located on chromosomes 7D ( QYr.sgi-7D) and 2B ( QYr.sgi-2B.1), contributing 29% and 30% to the phenotypic variance, respectively. QYr.sgi-2B.1 is primarily associated with a chlorotic and/or necrotic response, unlike QYr.sgi-7D, which is believed to be the adult plant resistance gene Yr18. These two QTLs for adult plant resistance in Kariega appear to represent different forms of resistance, where QYr.sgi-7D may represent potentially more durable resistance than QYr.sgi-2B.1. Mixture model analysis of the field leaf infection scores suggested a genetic model involving two independent genes combining in a classical, epistatic manner. The results of the QTL analysis demonstrate its higher resolution power compared to the mixture model analysis by detecting the presence of minor QTLs.

Basidiomycota↗
PubMed2004

An economical bioreactor for evaluating biogas potential of particulate biomass.

An economical bioreactor designed for evaluating the biogas potential of particulate biomass is described. The bioreactor uses a simple stirring apparatus, called the Bordeaux stirrer, to enable gas-tight mixing of fermentation cultures. The apparatus consists of a low-rpm motor connected to a bent steel stir rod, which is placed in a length of flexible plastic tubing inserted through a rubber stopper in a gas-tight manner. This stirrer is suitable for providing intermittent or continuous mixing in bench-scale anaerobic cultures containing particulate biomass. The reactor system may be operated as a batch-fed or semi-continuously fed digester. This communication documents the advantages of the stirring apparatus, describes the details of reactor fabrication and operation, and outlines the type of experimental work for which the bioreactor is suitable.

Bacteria, Anaerobic↗
PubMed2002

Prostatic stem cells.

Multipotent cells within the epithelial compartment, together with phenotypically 'plastic' mesenchyma cells (stromal stem cells), provide a repository of protected genetic information from which the structure, stability and functionality of the prostate gland can be maintained. However, mere preservation of cells in a non-dividing state is insufficient to provide the necessary reservoir of information from which the structure and function of the prostate gland can be retained or recreated. Rather, there is a constant dynamic interaction, at the level of information exchange, between stem cells (whether epithelial or mesenchymal) and their surrounding environment (both humoral and physical). Thus, with respect to epithelial stem cells, these reside within environmental 'niches' which allow their controlled and limited proliferation while preserving genomic integrity. Similar 'mesenchymal niches' are also predicted to occur, although not yet identified, thus providing the multipotent source from which the full spectrum of stromal phenotypes might be regenerated. Recent data from studies of the haematopoietic and hepato-biliary systems indicate that the potential scope of stem cells far exceeds the immediate phenotypic complement of those tissues within which they originate, being dependent upon their precise environment as well as their genomic integrity.

Cell Differentiation↗
PubMed2002

Effects of paired-pulse and repetitive stimulation on neurons in the rat medial geniculate body.

Many behaviorally relevant sounds, including language, are composed of brief, rapid, repetitive acoustic features. Recent studies suggest that abnormalities in producing and understanding spoken language are correlated with abnormal neural responsiveness to such auditory stimuli at higher auditory levels [Tallal et al., Science 271 (1996) 81-84; Wright et al., Nature 387 (1997) 176-178; Nagarajan et al., Proc. Natl. Acad. Sci. USA 96 (1999) 6483-6488] and with abnormal anatomical features in the auditory thalamus [Galaburda et al., Proc. Natl. Acad. Sci. USA 91 (1994) 8010-8013]. To begin to understand potential mechanisms for normal and abnormal transfer of sensory information to the cortex, we recorded the intracellular responses of medial geniculate body thalamocortical neurons in a rat brain slice preparation. Inferior colliculus or corticothalamic axons were excited by pairs or trains of electrical stimuli. Neurons receiving only excitatory collicular input had tufted dendritic morphology and displayed strong paired-pulse depression of their large, short-latency excitatory postsynaptic potentials. In contrast, geniculate neurons receiving excitatory and inhibitory collicular inputs could have stellate or tufted morphology and displayed much weaker depression or even paired-pulse facilitation of their smaller, longer-latency excitatory postsynaptic potentials. Depression was not blocked by ionotropic glutamate, GABA(A) or GABA(B) receptor antagonists. Facilitation was unaffected by GABA(A) receptor antagonists but was diminished by N-methyl-D-aspartate (NMDA) receptor blockade. Similar stimulation of the corticothalamic input always elicited paired-pulse facilitation. The NMDA-independent facilitation of the second cortical excitatory postsynaptic potential lasted longer and was more pronounced than that seen for the excitatory collicular inputs. Paired-pulse stimulation of isolated collicular inhibitory postsynaptic potentials generated little change in the second GABA(A) potential amplitude measured from the resting potential, but the GABA(B) amplitude was sensitive to the interstimulus interval. Train stimuli applied to collicular or cortical inputs generated intra-train responses that were often predicted by their paired-pulse behavior. Long-lasting responses following train stimulation of the collicular inputs were uncommon. In contrast, corticothalamic inputs often generated long-lasting depolarizing responses that were dependent on activation of a metabotropic glutamate receptor. Our results demonstrate that during repetitive afferent firing there are input-specific mechanisms controlling synaptic strength and membrane potential over short and long time scales. Furthermore, they suggest that there may be two classes of excitatory collicular input to medial geniculate neurons and a single class of small-terminal corticothalamic inputs, each of which has distinct features.

Animals↗
PubMed2002

Mutations in wheat showing altered field resistance to yellow and brown rust.

Intensive screening of a small population of mutagenised wheat lines revealed a large number of lines with altered resistance to both yellow and brown rust. The parental cultivar Guardian has an intermediate level of adult plant resistance to this disease; mutants were therefore isolated that showed either enhanced resistance or enhanced susceptibility to yellow rust. Seven lines were identified that gave an altered yellow rust disease phenotype as adult plants under both field and greenhouse conditions. Simultaneous field testing for brown rust infection identified two of these lines as having increased resistance to brown rust.

Fungi↗
PubMed2001

Fundamental differences between the thalamocortical recipient layers of the cat auditory and visual cortices.

In visual and somatosensory cortices of several species, spiny stellate cells in layer 4 are the first elements in signal processing where thalamic information is integrated and emergent receptive field properties are generated and sent on to more superficial cortical layers. In vivo and in vitro experiments have provided important information about how the anatomy and physiology of these cells and this layer fit into the functional cortical circuitry. No such data exist for the auditory cortex but are requisite if we are to understand whether ideas about information processing in one sensory cortical area can be generalized to another. Accordingly, we used in vitro slices from which to record and labeled cells in the middle layers of the cat auditory and visual cortices to compare basic anatomical and physiological features of cells recovered in similar layers using the same methods. Our results demonstrate a striking difference in a basic characteristic of two primary sensory cortical areas. In the visual cortex, spiny stellate cells predominate, receive short-latency synaptic inputs, and project to supergranular layers. No such spiny stellate population is encountered in the middle layers of the auditory cortex. Spiny cells that are not stellate or pyramidal are occasionally encountered but, as a group, do not display consistent anatomical or physiological features that might allow them to function as auditory cortical versions of the visual spiny stellates. Rather, pyramidal cells in the lower half of layer 3 and layer 4 appear to have assumed this role.

Animals↗
PubMed2001

Human cutaneous fatty acid-binding protein induces metastasis by up-regulating the expression of vascular endothelial growth factor gene in rat Rama 37 model cells.

Human cutaneous fatty acid-binding protein (C-FABP) gene is capable of inducing the metastatic phenotype when overexpressed in nonmetastatic rat Rama 37 cells. However, the mechanism of how it induces metastasis is not clear. Northern and slot blot analyses revealed that expression of the endogenous vascular endothelial growth factor (VEGF) gene was increased by 3.8-5.2-fold in the C-FABP-transfected cells (pSV-CFABP-R37) and in their metastatic sublines (e.g., Met-1) when compared with that in the nonmetastatic control transfectant pSV-R37 cells generated by transfection of only plasmid DNA. Higher levels of VEGF immunoreactive protein were also secreted from the malignant C-FABP-expressing cells. Reverse transcription-PCR detected two VEGF transcript isoforms, VEGF(164) and VEGF(188), in both the nonmetastatic control transfectant pSV-R37 cells and the malignant metastatic Met-1 cells. Chick chorioallantoic membrane assays showed that the conditioned medium of the control pSV-R37 cells possessed only very weak angiogenic activity, whereas conditioned media from the metastatic C-FABP transfectants and their sublines were strongly angiogenic and could be inhibited by antibodies to VEGF. Transfection of VEGF(164) cDNA in an expression vector into nonmetastatic Rama 37 cells produced a cell clone (R37-VEGF-2) that expressed high levels of VEGF. Inoculation of R37-VEGF-2 cells into syngeneic Wistar Furth rats produced metastases in a significant number (Fisher's exact test, P < 0.01) of animals (18 of 31 animals), whereas the control, vector alone-transfected R37-PSV cells produced no metastases (0 of 30 animals). Immunocytochemical methods demonstrated a strong positive staining for VEGF and an increased microvessel density in the primary tumors produced from PSV-VEGF-2 cells in comparison with tumors produced from control transfectants. Immunocytochemical staining for factor VIII detected a 3.5-fold increase in microvessel density of the primary tumors produced by PSV-VEGF-2 cells when compared with that of the primary tumors developed from the control pSV-R37 cells. Therefore, we suggest that overexpression of the C-FABP gene in the original transfectants induces metastasis through up-regulation of expression of the VEGF gene in this rat Rama 37 model system, and thus VEGF may play a crucial role in this particular metastatic cascade.

Animals↗
PubMed2001

Provision of MRI can significantly reduce CT collective dose.

The purpose of this study was to investigate the proportion of patients currently being investigated by CT that could be investigated by MRI with a potential reduction in exposure to ionizing radiation. The health detriment arising from the radiation dose associated with CT has been quantified in terms of the number of likely cases of serious health effects. The results show that a significant saving in the collective radiation dose is possible, with an associated detriment of between 0.23 and 0.33 cases of cancer or severe hereditary effects averted in one imaging department every year. In selecting the balance of provision of MRI and CT facilities, the health detriment associated with the radiation dose from CT should be considered.

Adolescent↗
PubMed2001

Assessment of clinical partner violence screening tools.

OBJECTIVE: To compare the Women's Experience with Battering Scale (WEB) with the Index of Spouse Abuse-Physical Scale (ISA-P) as screening tools to identify intimate partner violence (IPV). METHODS: We conducted a large cross-sectional survey of women age 18 to 65 attending one of two family practice clinics from 1997 to 1998. All women completed both the WEB and the ISA-P and a telephone interview. We figured agreement estimates between the two tools, used stratified analyses to evaluate attributes of those more likely to screen as battered or physically assaulted, and compared associations between the WEB and ISA-P and a range of mental and physical health indicators known to be associated with IPV. RESULTS: 18% of 1152 eligible women surveyed had experienced IPV in a current or most recent intimate relationship with a male partner; 17% had been battered (WEB+), and 10% had been physically assaulted (ISA-P+). Had we used the ISA-P alone to assess IPV, we would have missed almost 45% of IPV. As anticipated, the ISA-P was more strongly associated with IPV-associated injuries and number of physician visits in the last year. The WEB was more strongly associated with self-perceived mental health, anxiety, depression, drug abuse, and low social support. CONCLUSION: Clinicians need validated screening tools to rapidly and reliably screen patients for IPV. Most screening tools assess physical violence and injury without considering the more chronic experience of battering and the psychological terror associated with this violence. The WEB may identify more abused women than tools measuring physical assaults.

Adult↗
PubMed2000

Detection of synchrony in the activity of auditory nerve fibers by octopus cells of the mammalian cochlear nucleus.

The anatomical and biophysical specializations of octopus cells allow them to detect the coincident firing of groups of auditory nerve fibers and to convey the precise timing of that coincidence to their targets. Octopus cells occupy a sharply defined region of the most caudal and dorsal part of the mammalian ventral cochlear nucleus. The dendrites of octopus cells cross the bundle of auditory nerve fibers just proximal to where the fibers leave the ventral and enter the dorsal cochlear nucleus, each octopus cell spanning about one-third of the tonotopic array. Octopus cells are excited by auditory nerve fibers through the activation of rapid, calcium-permeable, alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors. Synaptic responses are shaped by the unusual biophysical characteristics of octopus cells. Octopus cells have very low input resistances (about 7 M Omega), and short time constants (about 200 microsec) as a consequence of the activation at rest of a hyperpolarization-activated mixed-cation conductance and a low-threshold, depolarization-activated potassium conductance. The low input resistance causes rapid synaptic currents to generate rapid and small synaptic potentials. Summation of small synaptic potentials from many fibers is required to bring an octopus cell to threshold. Not only does the low input resistance make individual excitatory postsynaptic potentials brief so that they must be generated within 1 msec to sum but also the voltage-sensitive conductances of octopus cells prevent firing if the activation of auditory nerve inputs is not sufficiently synchronous and depolarization is not sufficiently rapid. In vivo in cats, octopus cells can fire rapidly and respond with exceptionally well-timed action potentials to periodic, broadband sounds such as clicks. Thus both the anatomical specializations and the biophysical specializations make octopus cells detectors of the coincident firing of their auditory nerve fiber inputs.

Acoustic Stimulation↗
PubMed2000

Identification of the messenger RNA for human cutaneous fatty acid-binding protein as a metastasis inducer.

Using our recently developed systematic differential display and complete comparison of gene expression approaches combined with other methods, we have identified a large number of mRNAs that are expressed differentially between benign and malignant human cells. One such mRNA that is common to prostate and breast carcinoma cell lines encodes the human cutaneous fatty acid-binding protein (C-FABP). Northern and slot blot analyses confirm that the expression levels of C-FABP mRNA in the malignant prostate and breast carcinoma cell lines are 4.9+/-0.9- to 16.9+/-2.1-fold higher than those expressed in the benign cell lines. A similar difference between the benign and malignant cell lines was also detected at the protein level. In situ hybridization experiments have detected overexpression of the mRNA for C-FABP in human prostate carcinoma tissues. Transfection of a C-FABP expression construct into the benign, nonmetastatic rat mammary epithelial cell line Rama 37 and inoculation of the C-FABP expression transfectants into syngeneic Wistar-Furth rats produce a significant number (P < 0.05) of animals with metastases (6 of 26 animals), whereas the control transfectants generated by the vector alone yield no such metastases. Measurements of mRNA and protein levels with Northern and Western blotting show that C-FABP is not expressed in the control transfectant cells produced by the vector alone but is highly expressed in the pool of C-FABP transfectants and-the sublines established from their metastases. Immunocytochemical staining with antibodies to C-FABP shows that C-FABP is not expressed in the primary tumors developed from the control transfectants that have failed to metastasize, but it is expressed in both the primary tumors developed from the C-FABP transfectants and their metastases. Reinoculation of the sublines established from metastases in syngeneic rats has produced a higher proportion (50%) of animals (7 of 14 animals) with metastases than that obtained in the first-round inoculations, indicating that the metastatic clones have been preferentially selected from the original pool of metastatic and nonmetastatic transfectant clones. These results have demonstrated that elevated expression of C-FABP can induce metastasis and that metastatic capability has been transferred in a genetically dominated manner in this Rama 37 model. Thus, we suggest that C-FABP is a metastasis-inducing gene, and under suitable conditions, it may induce metastasis of some human cancers.

Animals↗
PubMed2000

Physical health consequences of physical and psychological intimate partner violence.

BACKGROUND: Past studies that have addressed the health effects of intimate partner violence (IPV) have defined IPV as violence based on physical blows that frequently cause injuries. To our knowledge, no epidemiologic research has assessed the physical health consequences of psychological forms of IPV. OBJECTIVE: To estimate IPV prevalence by type and associated physical health consequences among women seeking primary health care. DESIGN: Cross-sectional survey. SETTING AND PARTICIPANTS: A total of 1152 women, aged 18 to 65 years, recruited from family practice clinics from February 1997 through January 1999 and screened for IPV during a brief in-clinic interview; health history and current status were assessed in a follow-up interview. RESULTS: Of 1152 women surveyed, 53.6% ever experienced any type of partner violence; 13.6% experienced psychological IPV without physical IPV. Women experiencing psychological IPV were significantly more likely to report poor physical and mental health (adjusted relative risk [RR], 1.69 for physical health and 1.74 for mental health). Psychological IPV was associated with a number of adverse health outcomes, including a disability preventing work (adjusted RR, 1.49), arthritis (adjusted RR, 1.67), chronic pain (adjusted RR, 1.91), migraine (adjusted RR, 1.54) and other frequent headaches (adjusted RR, 1.41), stammering (adjusted RR, 2.31), sexually transmitted infections (adjusted RR, 1.82), chronic pelvic pain (adjusted RR, 1.62), stomach ulcers (adjusted RR, 1.72), spastic colon (adjusted RR, 3.62), and frequent indigestion, diarrhea, or constipation (adjusted RR, 1.30). Psychological IPV was as strongly associated with the majority of adverse health outcomes as was physical IPV. CONCLUSIONS: Psychological IPV has significant physical health consequences. To reduce the range of health consequences associated with IPV, clinicians should screen for psychological forms of IPV as well as physical and sexual IPV.

Adolescent↗