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Biomedical subjects

K Mueller

Publications and source records attributed to K Mueller.

At least 37 records · Page 2Linked to original sources
PubMed1998

Locomotor stereotypy produced by dexbenzetimide and scopolamine is reduced by SKF 83566, not sulpiride.

Like amphetamine, scopolamine produces locomotor stereotypy (repetitive routes of locomotion) in an open field. To determine whether locomotor stereotypy is a common behavioral effect of anticholingeric agents, several doses of the anticholinergic dexbenzetimide were tested for the ability to produce locomotor stereotypy; like scopolamine, dexbenzetimide produced locomotor stereotypy. To investigate a possible role of dopamine in anticholinergic-induced locomotor stereotypy, we tested the ability of the dopamine D1 antagonist SKF 83566 and the D2 antagonist sulpiride to block the locomotor stereotypy induced by scopolamine as well as dexbenzetimide. SKF 83566 blocked scopolamine- and dexbenzetimide-induced locomotor stereotypy; sulpiride did not reduce dexbenzetimide-induced locomotor stereotypy, but enhanced scopolamine-induced locomotor stereotypy. Hyperlocomotion was reduced by both dopamine antagonists. Results are interpreted in support of the notion that dopamine is the likely candidate mediating locomotor stereotypy.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1998

Recovery of free ADP, Pi, and free energy of ATP hydrolysis in human skeletal muscle.

We measured significant undershoots of the concentrations of free ADP ([ADP]) and Pi ([Pi]) and the free energy of ATP hydrolysis (DeltaGATP) below initial resting levels during recovery from severe ischemic exercise with 31P-nuclear magnetic resonance spectroscopy in 11 healthy sports students. Undershoots of the rate of oxidative phosphorylation would be predicted if the rate of oxidative phosphorylation would depend solely on free [ADP], [Pi], or DeltaGATP. However, undershoots of the rate of oxidative phosphorylation have not been reported in the literature. Furthermore, undershoots of the rate of oxidative phosphorylation are unlikely because there is evidence that a balance between ATP production and consumption cannot be achieved if an undershoot of the rate of oxidative phosphorylation actually occurs. Therefore, oxidative phosphorylation seems to depend not only on free [ADP], [Pi], or DeltaGATP. An explanation is that acidosis-related or other factors control oxidative phosphorylation additionally, at least under some conditions.

Adenosine Diphosphate↗
PubMed1998

Low level CO2 effects on pulmonary function in humans.

The purpose of the study was to determine whether chamber exposure to low levels of CO2 results in functional alterations in gas mixing and closing volume in humans. Four healthy volunteer subjects were exposed to 0.7% CO2 and to 1.2% CO2. Spirometry, lung volumes, single breath nitrogen washout, diffusing capacity for carbon monoxide (DLCO) by two methods, and cardiac output were measured in triplicate. Values were obtained over two non-consecutive days during the training period (control) and on days 2 or 3, 4, 6, 10, 13, and 23 of exposure to each CO2 level. Measurements were made during the same time of day. There was one day of testing after exposure, while still in the chamber but off carbon dioxide. The order of testing, up until measurements of DLCO and cardiac output, were randomized to avoid presentation effects. The consistent findings were a reduction in diffusing capacity for carbon monoxide and a fall in cardiac output, occurring to a similar degree with both exposures. For the group as a whole, there was no indication of major effects on spirometry, lung volumes, gas mixing or dead space. We conclude that small changes may occur in the function of distal gas exchanging units; however, these effects were not associated with any adverse health effects. The likelihood of pathophysiologic changes in lung function or structure with 0.7 or 1.2% CO2 exposure for this period of time, is therefore, low.

Breath Tests↗
PubMed1997

Capsaicin-resistant vagal afferent fibers in the rat gastrointestinal tract: anatomical identification and functional integrity.

The presence and distribution of vagal fibers and terminals throughout esophagus and gastrointestinal tract that could be anterogradely labeled by nodose ganglion tracer injections was quantitatively assessed in capsaicin- and vehicle-pretreated adult rats, in order to identify the capsaicin-resistant population. Up to 90% of the intraganglionic laminar endings (IGLEs), in the myenteric plexus of the esophagus, and 70-90% in the stomach, as well as 57% of the intramuscular endings or arrays (IMAs) in the fundic stomach survived the capsaicin treatment, while in the upper small intestine only few and in the lower small intestine, the cecum and colon, virtually no IGLEs survived capsaicin treatment. Intramucosal terminals were not assessed. Furthermore, gastric balloon distension-induced c-Fos expression in the dorsal vagal complex was not significantly decreased in capsaicin-treated rats. It is concluded that among primary vagal afferents there is a capsaicin-resistant population that primarily innervates the esophagus and upper gastrointestinal tract, and a capsaicin-sensitive population that innervates mainly the lower tract. At least vagal gastric tension-sensitive afferents also seems to be functionally intact in that they may be capable of synaptically activating second-order neurons in the brainstem.

Animals↗
PubMed1997

Amphetamine-induced locomotor stereotypy in rats is reduced by a D1 but not a D2 antagonist.

Amphetamine produces locomotor stereotypy (repetitive routes of locomotion) in an open field. In this research we tested the ability of the D1 antagonist SKF 83566 and the D2 antagonist sulpiride to block the locomotor stereotypy produced by 2 mg/kg amphetamine. SKF 83566 decreased amphetamine-induced locomotor stereotypy; sulpiride had no consistent effect on amphetamine-induced locomotor stereotypy. There was no evidence that either antagonist potentiated the effect of the other.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

The weighted-distance scheme: a globally optimizing projection ordering method for ART.

The order in which the projections are applied in the algebraic reconstruction technique (ART) has a great effect on speed of convergence, accuracy, and the amount of noise-like artifacts in the reconstructed image. In this paper, a new projection ordering scheme for ART is presented: the weighted-distance scheme (WDS). It heuristically optimizes the angular distance of a newly selected projection with respect to an extended sequence of previously applied projections. This sequence of influential projections may incorporate the complete set of all previously applied projections or any limited time interval subset thereof. The selection algorithm results in uniform sampling of the projection access space, minimizing correlation in the projection sequence. This produces more accurate images with less noise-like artifacts than previously suggested projection ordering schemes.

Algorithms↗
PubMed1996

A medical workstation for the display and analysis of multi-frame digital cineradiographic data.

A medical workstation has been developed for the efficient display and analysis of large sets of digital cineradiographic images. Various features aid the clinician in quickly identifying and extracting the image information relevant for diagnosis: animated viewing of image frames, a digital magnifying glass for local image enlargement and enhancement, a special review queue for critical image frames, and task-oriented image processing. Double frame buffering and direct memory addressing ensure fast, artifact-free image display and transfer. Much freedom is provided for adapting the system to one's own preferences. A statistical analysis of extensive tests conducted by eight clinical expert reviewers is given.

Cineradiography↗
PubMed1996

Fatal motor vehicle crashes: variations of crash characteristics within rural regions of different population densities.

OBJECTIVE: While it is known that motor vehicle crash (MVC) fatality rates are inversely related to population density, there has been no description of which crash variables are related to population density. The purpose of this study was to describe crash characteristics of fatal MVCs and to determine which crash characteristics are related to population density. DESIGN: This is a retrospective review of fatal accident reporting system (FARS) records. They represent four different population density regions over a 5-year period in a four-state midwest region. RESULTS: There were 10,932 people in 6,318 vehicles who were involved in 4,970 fatalities. Occupant fatality rates per 100,000 persons were inversely related to population density. The variables related to lower population density were more light and heavy truck types, more frequent alcohol use and higher levels of intoxication, more frequent crashes that are noncollisions on less heavily traveled roads, more frequent crashes on gravel surface types, more frequent occupant ejection, and delayed medical care. CONCLUSION: Rural areas are not homogenous in terms of fatal MVC crash characteristics. By analyzing fatal MVC crash characteristics in regions with different population densities, many crash variables were found to be related to population density. By understanding which characteristics about fatal MVCs are related to population densities, different interventions could be targeted to different rural populations.

Accidents, Traffic↗
PubMed1995

Health insurance status and ill health: implications for health professionals.

The article examines the relationship between health insurance status and the instances of self-reported ill health among 1,235 Nebraska adults. Ill health conditions include episodes of both acute and chronic conditions. Health status is measured as Medicare, Medicaid, private health insurance, veterans' benefits, and uninsured. Both Medicare and Medicaid are related to frequency of reported episodes of ill health, but only Medicare is related to reports of chronic conditions. Health professionals interested in improving and sustaining acceptable quality of health care should focus attention on the Medicare and Medicaid populations and not be concerned that adding the currently uninsured to the privately or publicly insured populations would, in the aggregate, increase their burdens of providing care. The study demonstrates the value of using population-based survey data to help health professionals anticipate and respond to patient demand.

Acute Disease↗
PubMed1995

Influence of hydration state on plasma volume changes during ultrafiltration.

To assess the influence of hydration state on plasma volume (PV) changes during ultrafiltration, 11 clinically normhydrated patients on maintenance hemodialysis were studied intraindividually during 2 hydration states differing by 2-15% of lean body mass (LBM). Plasma volume was measured continually during a 15-min ultrafiltration test including an ultrafiltration of 1% of target weight and during a 45-min follow-up period of blood recirculation through the dialyzer without ultrafiltration. In all patients a maximal decrease in relative PV was more pronounced when there was less hydration and when the grade of hydration correlated inversely with the maximal response of PV decrease (r = -0.68, p < 0.001). The same was observed between the hydration state and the slope of the PV decrease (r = -0.69, p < 0.001). Plasma refilling was estimated in the period following ultrafiltration. The slope of the plasma volume increase correlated with the grade of hydration (r = 0.31, p < 0.05) as did the asymtote of PV (r = 0.4, p < 0.01). It is concluded that the less hydrated a dialysis patient is, the more pronounced will be the fall of the ultrafiltration-induced plasma volume and the less distinct will be the recovery of the plasma volume after the discontinuation of ultrafiltration.

Adult↗
PubMed1995

Sumatriptan prophylaxis for postelectroconvulsive therapy headaches.

Very little has been written about headaches following electroconvulsive therapy (ECT) but the incidence has been estimated at 26%. Patients with a history of migraine occasionally have similar headaches precipitated by ECT. In addition, some patients may have headaches that persist for months after a series of ECT treatments, while some patients who have a preexisting headache problem report improvement with ECT. Serotonergic mechanisms have been proposed both for the efficacy of ECT and its tendency to produce headaches in susceptible patients. There have been no studies on the prophylaxis or treatment of post-ECT headache. While various strategies have been suggested for these headaches, even case reports documenting the efficacy of these strategies are lacking. We, therefore, report a case of severe, refractory, post-ECT headaches which responded to prophylactic treatment with sumatriptan.

Adult↗
PubMed1995

Access to health care: urban-rural comparisons from a midwestern agricultural state.

Lack of access to quality health care for a large number of Americans, particularly those living in rural areas, is a major health care problem. Differences in access between rural and urban areas are caused by obstacles to providing adequate care, such as hospital closures and physician shortages, and low income and/or employment that does not provide health insurance as an employee benefit. This study, based on a random sample of 6,000 households in Nebraska, finds that access to health care is better for residents of rural than urban areas. The relationship holds with controls for health status and health insurance. The pattern in Nebraska reflects an absence of differences in income, health insurance, and health status that produce differences in access between rural and urban areas nationwide. The findings suggest that any serious proposal to reform health care delivery should involve the states and use established patterns of seeking care among state residents.

Data Collection↗
PubMed1994

Protective function of extrinsic sensory neurons in acute rabbit experimental colitis.

BACKGROUND/AIMS: Sensory nerves appear to have a protective effect against acute injury in the gastric mucosa. Their function in the intestine is unclear. METHODS: In this study an immune-complex model of colitis was used to induce inflammation in the distal colon with and without functional ablation of sensory neurons by capsaicin pretreatment. RESULTS: Colitis was more severe in the capsaicin-pretreated group than in the vehicle group 48 and 96 hours after induction of colitis. Neutrophil infiltration, expressed as inflammatory index, was significantly increased to 4.25 +/- 0.4 vs. 1.83 +/- 0.5 at 48 hours and to 2.66 +/- 0.6 vs. 1.65 +/- 0.3 at 96 hours in the capsaicin group and the vehicle group, respectively. The microscopic ulcer index also was significantly increased in the capsaicin-pretreated group compared with the vehicle group (63.3 +/- 10.6 vs. 3.3 +/- 2.4 at 48 hours, 20.0 +/- 8.4 vs. 1.5 +/- 1.1 at 96 hours). Immunoreactive substance P (SP) and calcitonin gene-related peptide (CGRP) contents were decreased in extracts of inflamed compared with uninflamed colon. CONCLUSIONS: These data suggest that sensory neurons have a protective role in an acute rabbit model of experimental colitis by release of sensory neuropeptides (SP, CGRP), which may modulate vascular tone and mucosal blood flow.

Animals↗
PubMed1994

The effects of haloperidol, scopolamine, and MK-801 on amphetamine-induced increases in ascorbic and uric acid as determined by voltammetry in vivo.

Amphetamine (which enhances dopaminergic, cholinergic, and glutamatergic activity) increases release of ascorbic acid (AA) and uric acid (UA) in the caudate nucleus. In this study, linear sweep voltammetry with carbon past electrodes was used to investigate the effects of haloperidol (a DA receptor blocker), scopolamine (a muscarinic receptor blocker), and MK-801 (an NMDA receptor blocker) alone and in combination on amphetamine-induced increases in AA and UA in the caudate nucleus. Both scopolamine (0.5 mg/kg, IP) and MK-801 (0.5 mg/kg, IP) significantly reduced amphetamine-induced increases in AA. Also, scopolamine did not affect MK-801-induced reductions of amphetamine-induced increases in AA. Unexpectedly, a subthreshold dose of haloperidol (0.1 mg/kg, IP) potentiated the ability of scopolamine to block amphetamine-induced increases in AA. Therefore, the data suggest that acetylcholine release and subsequent binding to cholinergic receptors in the caudate, are components of amphetamine-induced increases in AA. In addition, scopolamine modulated haloperidol-induced reductions of amphetamine-induced increases in release of UA. Thus, our data demonstrate that cholinergic and dopaminergic systems may interact to control release of UA.

Amphetamine↗
PubMed1994

Stimulation of trabecular bone formation by insulin-like growth factor I in adult ovariectomized rats.

Although in vitro experiments indicate that insulin-like growth factor I (IGF-I) is an anabolic hormone in bone cell metabolism, the effects of IGF-I in vivo on bone formation are unclear. We thus investigated whether IGF-I is able to stimulate bone formation in adult rats with established osteopenia induced by ovariectomy (OVX). IGF-I was administered at daily doses of 0.05, 0.2, and 0.8 mg/kg for 3 wk. OVX induced a marked osteopenia in femur and tibia. Administration of IGF-I increased trabecular bone mass with a maximal effect at 0.2 mg/kg. The same dose stimulated bone formation, as revealed by an increase in osteoid surface, osteoblast surface, triple tetracycline-labeled surface, and bone formation rate. The mineral apposition rate was equally stimulated at all doses. At the highest dose, IGF-I increased osteoclast surface and osteoclast number. These data indicate that, in the adult OVX rat, IGF-I stimulates bone formation and increases trabecular bone volume at medium doses and enhances the histological indexes of bone resorption at high doses.

Alkaline Phosphatase↗
PubMed1994

Delivering services to the rural elderly: a study of policy implementation.

This article presents an analysis of two demonstration projects designed to improve delivery of services to elderly residents of rural Nebraska. One project employs a statewide system of care management focused on individual clients. In the other, local agencies in four communities coordinate services by using the local senior center as a focal point. This article uses established theory of policy implementation to illustrate problems encountered in starting new social programs that require state-local cooperation. Four guidelines are suggested for policymakers: (a) if local agencies are responsible for implementation, local managers must be involved in all the planning activities for new programs; (b) clear guidelines are needed to be sure that there is consensus concerning the details of implementation; (c) all health care providers should be involved in implementation when health care services are being coordinated; and (d) community coordinating councils can be effective.

Aged↗