Biomedical subjects

J Snell

Publications and source records attributed to J Snell.

At least 55 records · Page 3Linked to original sources

PubMed1995

Primary care. Three years after Tomlinson ... why millions are still unspent.

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Financing, Government↗

PubMed1995

Protection from oxidation enhances the survival of cultured mesencephalic neurons.

Oxidative stress has been linked to the destruction of dopaminergic neurons in the substantia nigra and may be a significant factor in both Parkinson's disease and MPTP toxicity. Using primary cultures of embryonic rat mesencephalon and standard immunocytochemical techniques, we have examined the survival of tyrosine hydroxylase-containing (TH+) neurons cultured in the presence of antioxidants and/or in an environment of low oxygen partial pressure. The number of TH+ neurons increased approximately twofold if superoxide dismutase, glutathione peroxidase (GP), or N-acetyl cysteine (NAC) were added to the culture media. Exposure of the neurons to a 5% oxygen environment (38 torr, i.e., 38 mm Hg) also increased the survival of TH+ neurons by about twofold. A dramatic enhancement of survival, however, was seen when NAC was used in combination with the 5% oxygen environment. In this case, the number of TH+ neurons increased fourfold from nontreated controls. Morphological changes were also noted. GP increased the average neurite length while NAC increased the average area of the cell body in the TH+ neuron. These results suggest that manipulation of oxidative conditions by changing the ambient O2 tension or the level of antioxidants promotes survival of TH+ neurons in culture and may have implications for transplantation therapies in Parkinson's disease.

Acetylcysteine↗

PubMed1995

The gray-scale ink-jet printer: value in making hard copies of digital images.

Referring physicians often are supplied with copies of images to illustrate a report of the findings of a radiologic study or so that the radiologist can retain the original images. The increasing costs of production, film, and recovery of chemicals have enhanced the requirement for a clean, low-cost dry printing process. An ink-jet gray-scale paper printer (Unitone, Scitex Medical Systems, Bedford, MA) can print high-quality (300 dots per inch [dpi]) images with an effective 10-bit gray scale range by using the Hertz continuous ink-jet method [1-3], which does not require the use of a darkroom or hazardous chemicals. Several types of media (matte paper, glossy paper, transparency film) with a printing area of 26.9 x 43.7 cm (10.6 x 17.4 inches) may be used. The consumables are approximately 50-70% less expensive than the cost of silver halide film, providing a cost advantage over film for referral and archival copies. The results of an initial evaluation of the ink-jet printer at our institution are reported here.

Computer Peripherals↗

PubMed1994

Induction of superoxide anion and nitric oxide production in cultured microglia.

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Animals↗

PubMed1994

Transverse abdominal incisions compared with midline incisions for elective infrarenal aortic reconstruction: predisposition to incisional hernia in patients with increased intraoperative blood loss.

PURPOSE: Both midline and transverse abdominal incisions are used for exposing the infrarenal aorta. Transverse incisions are said to cause less pulmonary and systemic complications, but the claimed advantages may be because most transverse incisions are extraperitoneal, whereas midline incisions are intraperitoneal. This study compares intraperitoneal transverse and midline incisions with respect to perioperative and late complications, especially incisional hernia. METHODS: Three hundred twenty-nine patients undergoing infrarenal aortic reconstruction (239 aneurysms; 90 occlusive disease) were analyzed retrospectively according to whether the abdominal wall incision was midline (154 patients) or transverse (175 patients). In all patients, the subsequent dissection was transperitoneal and not retroperitoneal. RESULTS: Perioperative survival rates and intraoperative blood loss were comparable, but the transverse incision tended to be followed by a shorter period of postoperative ileus (p = 0.07), perhaps because the small bowel was not always exteriorized during operation with transverse incisions. Mean time spent in the intensive care unit was not different between the groups, but those with transverse incisions remained in hospital 5 days less than those receiving midline incisions (p = 0.0005). When an aortic graft greater than 18 mm in diameter was used, survival was reduced compared with that after smaller grafts (p = 0.028). At 1 to 6 years follow-up in 235 patients (109 midline; 126 transverse), 35 (14.9%) incisional hernias were detected, with no statistical difference according to incision (16.5% midline; 13.4% transverse). Analysis by univariate and multivariate logistic regression showed that blood loss at operation exceeding 1000 ml increased the risk of later incisional hernia by a factor of 3.07. Wound infection increased the risk of hernia by 3.70. CONCLUSION: Excess blood loss and wound infection exerted this predisposition to incisional herniation independent of other variables.

Aged↗

PubMed1994

A study of stairs in the housing of independently-living elderly people.

This survey study focuses on stairs in the homes of a substantial number of independently living elderly (60+) residents of a community in which there are mostly multistory houses and apartment buildings with stairs. While the majority could climb their stairs without problems, a substantial minority lived with stairs despite difficulty and even inability in climbing them. Most people were satisfied with their homes, and many were unwilling to admit that stairs were a present or potential problem. Most people, including most with stair problems, had no plans to move from their homes, however, a majority was willing to concede under questioning that stair-free living in a presently unplanned next home would be desirable. There is a plea that stairs be of increased concern in the housing of elderly people, and that there be increased planning for stair-free homes.

Activities of Daily Living↗

PubMed1993

Noninvasive quantitative evaluation of atherosclerosis using MRI and image analysis.

A new medical image analysis system to quantify atherosclerosis in the lower abdominal aorta using magnetic resonance imaging is described. This medical image analysis and display system permits the quantification of the three-dimensional (3D) properties of the vessel wall and lumen cross-sectional area and volumes. Preliminary results of employing this medical image analysis capability on magnetic resonance images demonstrated a twofold increase in wall volume per unit vessel length, corresponding to intimal thickening, before luminal narrowing was detected. This work demonstrated the feasibility and usefulness of quantitatively evaluating the 3D properties of the vessel lumen and wall by using a combination of magnetic resonance imaging and image analysis. The demonstration that intimal wall thickening is observed in images before observable occlusion of the lumen can be expected to provide an important early indicator of the future development of atherosclerosis. Such capability will permit detailed and quantitative studies to assess the effectiveness of therapies, such as drug, exercise, and dietary regimens.

Aorta↗

PubMed1992

Pet ownership by elderly people: two new issues.

Two new issues of pet ownership were considered in a mail questionnaire and an interview survey of a large number of elderly people age sixty and over. First, evidence was obtained that pets are an important determinant of housing choice. Second, many elderly pet owners have made no arrangements for the pet if they predecease it or become unable to care for it. Problems related to these issues are discussed.

Activities of Daily Living↗

PubMed1986

Differential effects of sino-aortic denervations on cardiac noradrenaline stores, turnover and neuronal re-uptake in normotensive and renal hypertensive rabbits.

The effects of sino-aortic denervation (SAD) on cardiac noradrenaline stores, turnover and neuronal re-uptake were examined in normotensive rabbits and rabbits with two-kidney, two wrapped hypertension. Ten to 12 days after SAD, left ventricular (LV) noradrenaline stores were reduced in renal hypertensives to 43% of that of the sham-operated rabbits, although there was no overt evidence of heart failure. This did not occur after SAD of normotensive rabbits. The reduction in noradrenaline content was accompanied by a reduction in [3H]-noradrenaline turnover time (4.4 h) compared with renal hypertensive (7.4 h) and the normotensive subgroups (9.3 h). Noradrenaline turnover rates were elevated by 25% in hypertensive compared with normotensive rabbits. Left ventricular tyrosine hydroxylase, dopamine-beta-hydroxylase and type A monoamine oxidase activities were similar in normotensive and hypertensive rabbits and were unaffected by SAD. Following SAD of hypertensive rabbits cardiac neuronal uptake for alpha-methylnoradrenaline was reduced by 33% compared with either the hypertensive or the normotensive rabbits. Sino-aortic denervation did not affect neuronal uptake in normotensives. These results suggest that following SAD of hypertensive rabbits, cardiac noradrenaline stores are depleted by enhanced cardiac sympathetic activity (reduction in [3H]-noradrenaline turnover time) and a reduction in neuronal re-uptake. It appears that the hypertensive hypertrophied heart is less able to tolerate chronic sympathetic overactivity and/or liability in coronary oxygen supply brought about by SAD.

Animals↗

PubMed1982

Effects of noradrenergic neuronal activity on 3,4-dihydroxyphenylethylene glycol (DHPG) levels. Quantitation by high performance liquid chromatography.

We describe a sensitive specific and simple high pressure liquid chromatographic procedure for determining 3,4-dihydroxyphenyl-ethylene glycol (DHPG) in both plasma and tissue. DHPG is extracted from plasma or tissue extracts by adsorption onto alumina. DHPG in the alumina eluate is detected electrochemically following chromatography on a C18 reverse phase column. The method is sensitive enough to detect approximately 20 pg/ml of plasma DHPG. Both clonidine (100 micrograms/kg) and desmethylimipramine (2.5 mg/kg) when administered to rabbits for 3 days induced significant falls in both cardiac and plasma DHPG concentrations. These experiments indicate that both tissue and plasma DHPG concentrations may be of value in assessing both the release and re-uptake of norepinephrine at peripheral sympathetic nerve endings in vivo.

Animals↗

PubMed1982

Role of hyaline membrane disease in production of later childhood lung abnormalities.

Between 1961 and 1970, 177 survivors of hyaline membrane disease have been followed clinically and roentgenologically for a minimum of three years to determine the long-term pulmonary outcome. Of these, 153 have been seen for at least six years and 61, for 11 years or more. A total of 175 batteries of pulmonary function tests have been performed on 129 children at age 7 and/or 11 years, Final roentgenograms showed fibrosis in 12 instances, and these changes were positively correlated with the severity of the initial disease, the use of a positive pressure respirator (but not negative pressure respirator), time on the respirator, and length of time in O2, but not high O2 concentrations. Residual symptoms in the first years of life were also correlated with positive pressure respirator use, length of use, and with secondary infection. Pulmonary function tests showed minimal abnormalities in 12 children when last seen. None of these children had a history of exercise intolerance or chronic respiratory symptoms. The ultimate pulmonary history of this population of patients is unknown, but overt childhood lung disease following hyaline membrane disease is not a frequent occurrence.

Child↗

PubMedDate not supplied

Species differences in the generation of reactive oxygen species by microglia.

Although a variety of potential sources for reactive oxygen species (ROS) exist in the CNS, brain macrophages, i.e., the microglia, generate large quantities of these reactive species, particularly in response to injury or inflammatory signals. In order to understand how microglia contribute to changes in oxidative status of the CNS and how this might related to disease states, such as Alzheimer disease (AD), we have examined the regulation of superoxide anion and nitric oxide production from rodent and human microglia. Our results indicate that microglia from all species we have studied release superoxide anion, but produce significantly different amounts in response to the same activating agents. Species differences are also found in the ability to generate nitric oxide (NO). In particular, mouse microglia generate large quantities of NO when stimulated, but human and hamster microglia do not produce measurable amounts under the same stimulation conditions. These species differences are important to consider when modeling human disease processes from rodent studies.

Animals↗

PubMedDate not supplied