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Biomedical subjects

A G Hayes

Publications and source records attributed to A G Hayes.

At least 19 recordsLinked to original sources
PubMed2004

Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover.

The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (approximately 20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.

Calcium Sulfate↗
PubMed2004

Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum.

Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.

Atmosphere↗
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

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater.

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.

Atmosphere↗
PubMed1999

Cognitive abilities and adjustment with gabapentin: results of a multisite study.

The cognitive and quality of life effects of gabapentin are not yet well explored. While preliminary work in the area has provided positive findings, a large double-blinded study has been needed to explore this area more thoroughly. From 24 sites in North America, 201 adults were studied who had uncontrolled complex partial seizures with or without secondary generalization. Attempts were made to convert each patient from one or two marketed antiepileptic drugs (AEDs) taken in baseline to gabapentin monotherapy (600, 1200, or 2400 mg/day). Tests of cognitive abilities and adjustment were administered at the end of the 8-week baseline period and at the end of the 26-week double-blind treatment period. Analyses of baseline to treatment period changes were conducted for each dose group in comparison with a reference group of placebo-treated patients from another study. In the area of cognitive functioning, no changes in any of the gabapentin groups were found in comparison with the reference group. In the area of adjustment and mood, however, improvement with gabapentin administration was noted on several variables pertaining to emotional and interpersonal adjustment. These results are consistent with findings from previous studies.

Acetates↗
PubMed1996

Extensile posterior approach to the ankle.

Surgical exposure of the ankle is usually obtained by an anterior approach, especially for replacement arthroplasty. The transfibular approach has been popular for arthrodesis. We describe a new posterior approach to the ankle and posterior subtalar joint based on an extra-articular vertical calcaneal osteotomy behind the subtalar joint. The posterior flap so formed is hinged medially and offers wide exposure of the back of the ankle and posterior subtalar joint. This hinge allows safe and stable reduction of the osteotomised calcaneum, and the plane of dissection follows an 'internervous plane' behind the fibula. We have had good results after using this incision in 12 patients with osteoarthritis or rheumatoid arthritis and there have been no difficulties with wound healing.

Adult↗
PubMed1994

Frequency and distribution of medial and lateral patellar luxation in dogs: 124 cases (1982-1992).

From the medical records of 124 dogs, patellar luxations were classified as congenital or acquired, medial or lateral, and unilateral or bilateral; were graded 1 to 4; and were subdivided according to size of dog. The 4 breed-size categories were based on guidelines from American Kennel Club standards for adult height and weight. Findings from these records were compared with the results from dogs with other orthopedic problems. A majority of dogs had congenital (91; 82%), as opposed to acquired (17; 15%) patellar luxations. Distribution of dogs with patellar luxations according to breed size included 54 (98%) with medial patellar luxations (MPL) and 1 (2%) with lateral patellar luxation (LPL) in small breeds, 17 (81%) with MPL and 4 (19%) with LPL in medium breeds, 35 (83%) with MPL and 7 (17%) with LPL in large breeds; and 4 (67%) with MPL and 2 (33%) with LPL in giant breeds. Medial patellar luxation was observed in 110 dogs and 14 dogs had LPL. Cases of MPL and LPL in the same stifle or of medial and lateral patellar luxation in contralateral stifles in the same dog were not observed. Surgical correction was performed primarily in dogs with grade-3 and grade-4 patellar luxations. Medial patellar luxations and LPL were detected in all breed categories. Small-breed dogs were admitted almost exclusively with MPL. Lateral patellar luxation was found uncommonly; however, it was observed more often in larger-breed dogs. Prevalence of MPL was greater, when compared with that for LPL, in every size/breed category.

Animals↗
PubMed1994

4-[(Alkylamino)methyl]furo[3,2-c]pyridines: a new series of selective kappa-receptor agonists.

The synthesis of 5-(arylacetyl)-4-[(alkylamino)methyl]furo[3,2-c] pyridines (16-23, 26, 27) and their activities as kappa-opioid receptor agonists are described. kappa-Agonist potency was particularly sensitive to the nature of the basic moiety. In particular, in the rabbit vas deferens (kappa-specific tissue), the 3-pyrrolidinol analogue 17 (IC50 = 2.7 nM) was found to be approximately 5-fold more potent than the corresponding pyrrolidine analogue 16 (IC50 = 15 nM). In the rat and hamster vasa deferentia (mu-specific and delta-specific tissues, respectively), 17 showed only weak antagonist activity (pKB > 5.5), underlining its selectivity for the kappa-opioid receptor. The major activity for 17 is resident in the 4S,3'S-isomer 26 (rabbit vas deferens IC50 = 1.1 nM). Compound 26 displays excellent antinociceptive activity, as determined in the mouse acetylcholine-induced abdominal constriction test (ED50 = 0.001 mg/kg, sc).

Analgesics↗
PubMed1994

Acute and chronic behavioural sequelae resulting from intrastriatal injection of an NMDA agonist.

Unilateral and bilateral injections of cis-2,4-methanoglutamate, a potent and selective NMDA agonist, were made into the striatum of rats. Unilateral injections elicited MK-801-sensitive dose-related increases in contralateral turning, beginning 10-15 min after injection. Bilateral injections elicited typical seizure-like behaviours commencing approximately 80 min postinjection. Forty-eight hours after unilateral injection, and presumably after lesion development, no spontaneous preference for turning was seen. Upon challenge with apomorphine (1 mg/kg SC), ipsilateral turning lasting approximately 60 min was seen. Correlates are drawn between this model and some of the features of Huntington's disease.

Animals↗
PubMed1993

A potent new class of kappa-receptor agonist: 4-substituted 1-(arylacetyl)-2-[(dialkylamino)methyl]piperazines.

The synthesis of 4-substituted 1-(arylacetyl)-2-[(alkylamino)methyl]piperazines (10-22, 26, 27, and 30-33) and their activities as kappa-opioid receptor agonists are described. This includes a range of 4-acyl and 4-carboalkoxy derivatives with the latter series showing the greatest kappa-agonist activity. In particular, methyl 4-[(3,4-dichlorophenyl)acetyl]-3-[(1-pyrrolidinyl) methyl]-1-piperazinecarboxylate (18) displays exceptional potency and selectivity. It showed the following activities in functional in vitro assays: rabbit vas deferens (kappa-specific tissue) IC50 = 0.041 nM, rat vas deferens (mu-specific tissue) IC50 > 10,000 nM, and hamster vas deferens (delta-specific tissue) IC50 > 10,000 nM. Compound 18 is also a highly potent antinociceptive agent, as determined in the mouse acetylcholine-induced abdominal constriction test: ED50 = 0.000 52 mg/kg, sc. The activity of 18 resides solely in its 3(R)-enantiomer. The kappa-agonist activity in both the 4-acyl and the 4-carbamate series is sensitive to the size of the 4-substituent. In addition, it would appear that an appreciable negative electrostatic potential in this region of the molecule is an important requirement for optimal potency.

Analgesics↗
PubMed1993

Necrosis of the hand after extravasation of intravenously administered phenytoin.

Extravascular escape of intravenously administered phenytoin can result in serious local soft tissue complications. Injury can range from simple phlebitis to chemical cellulitis or, in extreme cases, frank tissue necrosis that necessitates amputation. The histopathologic findings include extensive necrosis and sloughing of epidermis, widespread necrosis of dermis, subcutaneous tissue, muscles and nerves, and extensive thrombotic occlusion of vessel lumens. Results of elastic tissue stains reveal that the thrombosed vessels are exclusively veins and venules. Vascular fibrinoid necrosis, leukocytoclasis, and true inflammatory vasculitis are not features. This is the first detailed report of the histopathologic alterations associated with this therapeutic misadventure.

Amputation, Surgical↗
PubMed1992

Cutaneous metastasis from squamous cell carcinoma of the cervix.

Metastasis to the skin occurs rarely, regardless of the nature of the primary systemic neoplasm. Although carcinoma of the cervix is the fourth most common malignancy in women, cutaneous involvement originating from cervical cancer is particularly unusual, even in the terminal stages of disease. Only 22 cases, including this one, are clearly documented in the literature. The main sites of the cutaneous metastases in these cases were the abdominal wall or lower extremity. However, we describe a 41-year-old woman with cervical cancer who developed metastatic nodules on the upper back. The skin of the back is an uncommon location for metastasis from any malignant tumor, and when it occurs in women, it is generally associated with carcinoma of the breast or malignant melanoma. To the best of our knowledge, this is the first reported case of cervical carcinoma metastasis to this unlikely cutaneous site.

Abdominal Neoplasms↗
PubMed1992

Synthesis, antinociceptive activity, and opioid receptor profiles of substituted trans-3-(decahydro- and octahydro-4a-isoquinolinyl)phenols.

A series of trans-3-(6- and 7-substituted-decahydro-4a-isoquinolinyl)phenols and trans-3-(octahydro-4a-isoquinolinyl)phenols have been synthesized as potential opioid analgesics. Using a combination of in vitro and in vivo test systems, the receptor profiles of selected compounds have been assessed and in some instances distinguish between mu- and kappa-receptor agonists. In general, introduction of a 6-exocyclic methylene group into the trans-3-(decahydro-4a-isoquinolinyl)phenol system enhanced both antinociceptive activity and kappa-opioid receptor selectivity. For each series, analogues bearing an N-cyclopropylmethyl substituent exhibited greater kappa-receptor selectivity while N-methyl derivatives showed greater mu-receptor selectivity. The 7-substituted compounds (3b) were significantly less potent antinociceptive agents than their 6-substituted counterparts (3a), the octahydroisoquinoline analogues exhibiting intermediate activity. The axial 8-methyl-6-exocyclic methylene isoquinoline (20) is the most potent compound in the mouse abdominal constriction assay (ED50 = 0.05 mg/kg sc), whereas the equatorial 8-methyl isomer (16) was significantly less potent (ED50 = 3.3 mg/kg sc).

Analgesics↗