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At least 847 records · Page 47Linked to original sources
PubMed1998

Reversible prolonged pacemaker failure due to electrocautery.

Despite improved technology, permanent pacemakers remain susceptible to electromagnetic interference, including electrocautery. We describe sudden, apparently irreversible output loss in a pacemaker associated with the use of electrocautery, despite standard precautionary measures. When tested by the manufacturer several weeks later, pulse generator function was normal and it was functioning in the "reset" mode. We postulate that pacemaker failure was related to current drain causing "lockout" of the voltage control oscillator, the mechanism responsible for regulating pulse width. Further reduction in battery voltage, due either to exposure to cold temperatures while the device was being transported to the manufacturer or to further use of electrocautery during device explanation, may have allowed it to reach the "reset" level, permitting normal function to resume.

Aged↗
PubMed2001

An outbreak of respiratory disease complex in sheep in Central Ethiopia.

An investigation was carried out into an outbreak of respiratory disease complex (RDC) in 3641 Menz and Awassi x Menz cross sheep in Central Ethiopia between 1998 and 1999 by clinical, serological, microbiological, post-mortem and histopathological examinations. The monthly incidence of RDC varied from 2.8% to 4.0% and the prevalence was as high as 17%. The case fatality rate was 18%, despite culling of sick sheep. Over 76% of the morbidity occurred in adults, followed by 19% among weaners. Similarly, 62% of the mortality was in adults. However, 27% of the mortality occurred in lambs despite the low morbidity in the group. Significant breed and age differences were seen in the morbidity and mortality rates (p < 0.05). Clinical signs, gross and microscopic lesions and serological and bacteriological examinations showed an interplay of several causes of the RDC, including pestes des petits ruminants (PPR) (72.3%, serologically confirmed), lung worms, maedi-visna, bacterial bronchopneumonia (staphylococcal and streptococcal), enzootic pneumonia and some fungal infections. Cold temperatures, which may be as low as -8.5 degrees C at night, are major predisposing factors along with managemental stresses. Vaccination of animals with a homologous PPR vaccine appeared to decrease dramatically the occurrence of the disease, showing that PPR played an important role in the outbreak. Several of the pathogens do not appear to be individually capable of causing the respiratory disease. Appropriate strategies for the prevention of RDC are suggested.

Animal Husbandry↗
PubMed2003

Changes in the metabolic activity of neurons in the anterior hypothalamic nuclei in rats during hyperthermia, fever, and hypothermia.

Histochemical methods were used to detect differently directed changes in the metabolic activity of neurons in the anterior hypothalamic nuclei in rats during hyperthermia, fever, and hypothermia. Hyperthermia induced by high temperatures was associated with increases in the activities of enzymes involved in energy metabolism, with increases in RNA contents in neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus of the rat, which is evidence for increases in metabolic activity in the neurons of these nuclei. Endotoxin-induced fever was accompanied by decreases in the metabolic activity of neurons in the median preoptic nucleus, while activity in neurons of the supraoptic and paraventricular nuclei showed no significant change. The development of hypothermia induced by low temperatures was characterized by decreases in the metabolic activity of neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus. It is suggested that the differently directed changes in metabolic activity in the neurons of the anterior hypothalamus in hyperthermia, fever, and hypothermia are associated with their roles in the central mechanisms of thermoregulation (median preoptic nucleus) and neurosecretory processes (supraoptic and paraventricular nuclei).

Animals↗
PubMed2003

Characterization of an Arabidopsis mutant deficient in gamma-tocopherol methyltransferase.

Alpha-tocopherol (vitamin E) is synthesized from gamma-tocopherol in chloroplasts by gamma-tocopherol methyltransferase (gamma-TMT; VTE4). Leaves of many plant species including Arabidopsis contain high levels of alpha-tocopherol, but are low in gamma-tocopherol. To unravel the function of different forms of tocopherol in plants, an Arabidopsis plant (vte4-1) carrying a functional null mutation in the gene gamma-TMT was isolated by screening a mutant population via thin-layer chromatography. A second mutant allele (vte4-2) carrying a T-DNA insertion in the coding sequence of gamma-TMT was identified in a T-DNA tagged mutant population. In vte4-1 and vte4-2 leaves, high levels of gamma-tocopherol accumulated, whereas alpha-tocopherol was absent indicating that, presumably, these two mutants represents null alleles. Over-expression of the gamma-TMT cDNA in vte4-1 restored wild-type tocopherol composition. Mutant plants were very similar to wild type. During oxidative stress (high light, high temperature, cold treatment) the amounts of alpha-tocopherol and gamma-tocopherol increased in wild type, and gamma-tocopherol in vte4-1. However, chlorophyll content and photosynthetic quantum yield were very similar in wild type and vte4-1, suggesting that alpha-tocopherol can be replaced by gamma-tocopherol in vte4-1 to protect the photosynthetic apparatus against oxidative stress. Fatty acid and lipid composition were very similar in WT, vte4-1 and vte1, an Arabidopsis mutant previously isolated which is completely devoid of tocopherol. Therefore, a shift in tocopherol composition or the absence of tocopherol has no major impact on the amounts of specific fatty acids or on lipid hydrolysis.

Arabidopsis↗
PubMed1998

A cytokinesis checkpoint requiring the yeast homologue of an APC-binding protein.

Checkpoint controls ensure that events of the cell-division cycle are completed with fidelity and in the correct order. In budding yeast with a mutation in the motor protein dynein, the mitotic spindle is often misaligned and therefore slow to enter the neck between mother cell and budding daughter cell. When this occurs, cytokinesis (division of the cytoplasm into two) is delayed until the spindle is properly positioned. Here we describe mutations that abolish this delay, indicating the existence of a new checkpoint mechanism. One mutation lies in the gene encoding the yeast homologue of EB1, a human protein that binds the adenomatous polyposis coli (APC) protein, a tumour suppressor. EB1 is located on microtubules of the mitotic spindle and is important in spindle assembly. EB1 may therefore, by associating with microtubules, contribute to the sensor mechanism that activates the checkpoint. Another mutation affects Stt4, a phosphatidylinositol-4-OH kinase. Cold temperature is an environmental stimulus that causes misalignment of the mitotic spindle in yeast and appears to activate this checkpoint mechanism.

1-Phosphatidylinositol 4-Kinase↗
PubMedDate not supplied

Assembly of microtubules from nucleotide-depleted tubulin.

In vitro assembly of microtubules from tubulin is considered to have an absolute requirement for added GTP (or a non-hydrolysable GTP-analogue) involving binding at the E(exchangeable)-site located on the beta-subunit of the tubulin dimer. By contrast, GDP inhibits assembly. Nucleotide hydrolysis has been implicated in the dynamic properties of microtubules, treadmilling and mechanical coupling. Here we demonstrate that assembly is not necessarily dependent on the presence of GTP at the E-site; microtubules can be formed efficiently in the absence of GTP in the presence of pyrophosphate. These microtubules, which have normal morphology and lability at cold temperatures, contain N(non-exchangeable)-site GTP and a significant proportion of E-site GDP. This demonstrates the possibility of direct incorporation of GDP-containing tubulin dimer during assembly which probably derives from microtubule-associated protein (MAP)-containing oligomers. This finding has important implications for the mechanism of microtubule elongation. The effects of pyrophosphate suggest that charge neutralization by the bidentate ligand is an essential step in promoting microtubule assembly, and that this interaction involves only a minimal conformational change in the protein.

Alkaline Phosphatase↗
PubMed2006

The sequestration of ethane on Titan in smog particles.

Saturn's largest satellite, Titan, has a dense atmosphere of nitrogen with a few per cent of methane. At visible wavelengths its surface is hidden by dense orange-brown smog, which is produced in the stratosphere by photochemical reactions following the dissociation of methane by solar ultraviolet light. The most abundant of the products of these reactions is ethane, and enough of it should have been generated over the life of the Solar System to form a satellite-wide ocean one kilometre deep. Radar observations have found specular reflections in 75 per cent of the surface spots observed, but optical searches for a sun-glint off an ocean have been negative. Here I explain the mysterious absence or rarity of liquid ethane: it condenses onto the smog particles, instead of into liquid drops, at the cold temperatures in Titan's atmosphere. This dusty combination of smog and ethane, forming deposits several kilometres thick on the surface, including the observed dunes and dark areas, could be named 'smust'. This satellite-wide deposit replaces the ocean long thought to be an important feature of Titan.

Journal Article↗
PubMed1997

Visual detection of transport-P in peptidergic neurones.

1. Hypothalamic peptidergic neurones possess an uptake process for amines (transport-P), for which prazosin is a substrate. It is characterized by a paradoxical increase in the accumulation of [3H]-prazosin when the concentration of unlabelled prazosin is increased above 10(-7) M. This increase is due to activation of a proton-dependent, vacuolar-type ATPase-linked pump that is blocked by tricyclic antidepressants. This study utilized a fluorescence method to detect amine uptake in individual cells. 2. Prazosin is fluorescent but most of its emission spectrum is in the ultraviolet range. We therefore used an analogue of prazosin in which the furan ring had been substituted with a fluorescent group, BODIPY FL. This compound's emission maximum is in the green part of the visible spectrum. 3. BODIPY FL prazosin accumulated in immortalised peptidergic neurones and the characteristic emission spectrum of the compound was evident in these cells. Accumulation of BODIPY FL prazosin was saturable and was inhibited by the tricyclic antidepressant desipramine and by unlabelled prazosin. As previously described for prazosin, uptake of BODIPY FL prazosin was blocked by cold temperature and by the organic base chloroquine. Thus, prazosin and BODIPY FL prazosin were accumulated by the same uptake process. 4. BODIPY FL prazosin accumulated in a granular distribution, which is compatible with storage in intracellular vesicles. 5. Hypothalamic cells from foetal rats in primary culture also accumulated BODIPY FL prazosin by a desipramine-sensitive process. Uptake was predominantly in neurones and glial cells did not accumulate the amine. 6. Fluorescent detection provides visual evidence for amine uptake in peptidergic neurones and should enable detailed study of the distribution of this process in the brain.

Adrenergic alpha-Antagonists↗
PubMed2004

Attempted reduction of 1,2,3-thiadiazole-4-carboxylates with samarium/iodine in methanol. Unexpected ring enlargement to 1,2,5-trithiepan-4,6-dicarboxylates.

When stirred with powdered samarium and iodine in methanol at ice-cold temperature, ethyl 1,2,3-thiadiazole-4-carboxylate 5 underwent unusual reduction involving the dimeric ring enlargement with a sulfur addition, giving dimethyl 1,2,5-trithiepan-4,6-dicarboxylates 7a,b as a cis/trans-isomeric mixture in acceptable yield. The 1,2,3-thiadiazole ring of 5 proved to resist reduction by ordinary reducing agents, where the only choice in most cases was either recovery of the unchanged substrate or decomposition to an intractable mixture of unidentified products and tar.

Heterocyclic Compounds, 1-Ring↗
PubMed1998

Human sudomotor responses to heating and cooling upper-body skin surfaces: cutaneous thermal sensitivity.

The influence of local skin temperature (Tskl) on the control of local and whole-body sweating was evaluated in eight healthy males. A water-perfusion garment (37 degrees C) and a climatic chamber (36.45 +/- 0.78 degrees C; [+/- SD]; relative humidity 60.3 +/- 1.6%) were used to raise and clamp skin and core temperatures. Warm and cool stimuli were applied to four upper-body skin regions (face, arm, forearm, hand) using perfusion patches (249.0 +/- 0.2 cm2). Heating elevated, while cooling suppressed sweat rate (msw) locally, and at other skin surfaces. However, the tendency for Tskl manipulations to induce localized sweat responses was no more powerful than it was at stimulating sweating in non-treated regions (P > 0.05). Accordingly, neither thermal stimulus produced significantly greater local sudomotor influences than were elicited contralaterally (P > 0.05). No statistical support was found for the notion of inter-regional differences in upper-body cutaneous thermal sensitivity for sudomotor control, and, regardless of the stimulation site, whole-body sudomotor responses to localized thermal treatments were equivalent (P > 0.05).

Acclimatization↗
PubMed2000

An investigation of temperature and stress distribution on a restored maxillary second premolar tooth using a three-dimensional finite element method.

This paper presents the stress analysis of the maxillary second premolar tooth under thermal loading as a result of hot/cold liquid in the mouth using the three-dimensional (3D) finite element method (FEM). The tooth was considered to be in a restored state with composite resin and amalgam on glass-ionomer as the base material. In the first step of the study, the temperature changes as a result of hot/cold liquid in the mouth were calculated. The thermal stress distributions owing to the temperature changes were then obtained. All calculation programs were prepared by the authors using FORTRAN 77. The tooth was assumed to be isotropic, homogeneous, elastic and unsymmetric. The distribution of temperature and stress were plotted for some critical points.

Bicuspid↗
PubMed2002

When exactly can carpal tunnel syndrome be considered work-related?

BACKGROUND: Carpal tunnel syndrome (CTS), compression of the median nerve at the wrist, is the most frequently encountered peripheral entrapment neuropathy. Whilst rates of all other work-related conditions have declined, the number of work-related musculoskeletal disorders (which include CTS) has not changed for the past 9 years in the USA. Median days off work are also highest for CTS: 27 compared to 20 for fractures and 18 for amputations. This results in enormous Workers Compensation and other costs to the community. Awareness of CTS as a disorder associated with repeated trauma at work is now so widespread amongst workers that many have diagnosed themselves before being medically assessed, often by means of the Internet. Surprisingly, however, a definite causal relationship has not yet been established for most occupations. Although the quality of research in this area is generally poor, CTS research studies are being used as the basis for acceptance of Workers Compensation claims, substantial expensive ergonomic workplace change and even workplace closures. The fact that the incidence of work-related musculoskeletal disorders has not changed despite these latter measures would suggest that a causal relationship is not proven and that some resources are being misdirected in CTS prevention and treatment. METHOD: A literature review of 64 articles on CTS was conducted. This included those articles most frequently cited as demonstrating the relationship between CTS and work. RESULTS: Primary risk factors in the development of CTS are: being a woman of menopausal age, obesity or lack of fitness, diabetes or having a family history of diabetes, osteoarthritis of the carpometacarpal joint of the thumb, smoking, and lifetime alcohol intake. In most cases, work acts as the 'last straw' in CTS causation. CONCLUSION: Except in the case of work that involves very cold temperatures (possibly in conjunction with load and repetition) such as butchery, work is less likely than demographic and disease-related variables to cause CTS. To label other types of work as having caused CTS, therefore, would result in inappropriate allocation of resources. It would also relieve individuals of the responsibility of addressing correctable lifestyle factors and treatable illnesses such as obesity, diabetes, smoking and increased alcohol intake which may have contributed to their CTS more that their work. This results in both avoidable long-term health effects and ongoing costs to the community.

Adult↗