Biomedical subjects

M Gallagher

Publications and source records attributed to M Gallagher.

At least 37 records · Page 2Linked to original sources

PubMed1994

Pain inhibition of shoulder strength in patients with impingement syndrome.

Fourteen patients with Stage II or III impingement syndrome (average age 58 years) were studied. Nine patients had full-thickness rotator cuff tears documented by arthrograms. Patients initially underwent a thorough shoulder examination followed by baseline isokinetic strength testing. Abduction/adduction testing was performed utilizing a Biodex dynamometer. Maximum concentric contractions were performed, and values for peak torque (PT), total work (W), and power (P) were obtained. All patients received a subacromial injection of 5 cc 1% lidocaine plus 5 cc 0.5% bupivacaine (Marcaine). After 5 minutes the testing sequence was repeated. Clinically, patients demonstrated marked improvement following injection. Eighty-six percent reported complete pain relief; the remaining two patients reported only mild discomfort at the extremes of motion. Improvement in functional activity of the affected shoulder was noted by all subjects. On manual muscle testing, 13 of 14 patients (93%) demonstrated increased abduction strength; 11 of 14 (79%) had improvement in external rotation. Mean increases in active forward elevation and external rotation were 36 degrees and 11 degrees, respectively (P < .01). Postinjection isokinetic changes in PT, W, and P for abduction/adduction were dramatic. For abduction, all patients showed significant increases in P (mean 82%), W (mean 90%), and PT (mean 48%) (all P < .05). No significant differences in range of motion testing or strength parameters were noted based on the presence or absence of a rotator cuff tear. For adduction, all patients showed significant increases in P (mean 208%), W (mean 183%), and PT (mean 41%) (all P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Animal models of normal aging: relationship between cognitive decline and markers in hippocampal circuitry.

Alzheimer's disease (AD) occurs against a background of cognitive and neurobiological aging. Animal models of normal aging may be used to study the neurobiological structures that are most involved in AD pathology, i.e. hippocampal/cortical systems. For example, spatial learning is dependent upon the integrity of the hippocampus, a structure that is much affected in humans with AD. Spatial learning tasks, such as the Morris water maze, have been used to screen aged rats for cognitive status prior to neurobiological assessment of hippocampal circuitry. Manifestations of the aging process, which are often minimal or entirely obscured in studies comparing young and aged brains, become apparent when the cognitive status of aged animals is taken into account. For example, studies examining the septohippocampal cholinergic system in behaviorally-characterized rodents have shown that there is a decline in many markers for these cholinergic neurons that coincides with severity of spatial learning impairment. Another advantage of cognitive assessment in animal models used to study aging is that it may help to distinguish between those neurobiological changes that are functionally detrimental and those that may represent compensatory adaptations to maintain cognitive function. Age-related changes in two neurobiological measures in the hippocampus are discussed in this report. Alterations in the opioid peptide dynorphin (increased peptide content and prodynorphin mRNA) in hippocampus may contribute to impairment in that the greatest changes occur in those aged rats with severe spatial learning deficits.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1993

The effects of aging on diurnal water intake and melatonin binding in the suprachiasmatic nucleus.

In vitro autoradiography was used to quantify [125I]melatonin binding in young rats and in aged rats that were screened for diurnal drinking prior to neurobiological study. Among the aged subjects studied, some rats exhibited a blunted diurnal rhythm in that a decreased percentage of water was consumed during the dark phase. Other aged animals maintained a strong nocturnal pattern of water intake similar to young rats. The density of [125I]melatonin binding in the suprachiasmatic nucleus (SCN) of the hypothalamus was significantly correlated with diurnal drinking, i.e. lower binding was associated with a more blunted rhythm. Thus, [125I]melatonin binding in the SCN may provide a marker for age-related decline in some aspects of biological functions.

Aging↗

PubMed1993

Peptide splicing in the vacuolar ATPase subunit A from Candida tropicalis.

Subunit A of the vacuolar proton pump appears to be responsible for the ATP hydrolysis which is coupled to the pumping of protons into a variety of intracellular acid compartments, including the fungal vacuole. We report here the cloning and sequence determination of the gene encoding subunit A from Candida tropicalis. Southern blot hybridization analysis indicates that there is a single gene which encodes this protein. The gene contains a single intron at the extreme 5'-end of the coding region. The gene is predicted to encode a polypeptide of 1088 residues with a calculated molecular mass of 119,019 daltons, yet the mature polypeptide appears to be approximately 67 kDa, indicating that this protein probably undergoes the same sort of processing that is evidenced in the homologous protein from Saccharomyces cerevisiae in which an approximately 50-kDa polypeptide (the spacer) is spliced out of the mature protein. The Candida gene, with and without this middle portion, has been expressed in S. cerevisiae and found to restore a Saccharomyces subunit A deletion mutant (tfp1-delta 8) to apparently wild-type growth at pH 7.6, and normal vacuolar acidification. The peptide sequence of the two predicted mature ends is very similar to the sequences of the analogous proteins from Daucus carota, S. cerevisiae, and Neurospora crassa (60.5, 87.4, and 72.9% identity, respectively), but the middle portion bears only very limited homology with the Saccharomyces protein sequence. Processing of the gene product occurs in S. cerevisiae, Escherichia coli, and in rabbit reticulocyte-mediated in vitro translation, indicating that the excision is probably autocatalytic. The limited sequence identity seen between the Saccharomyces and Candida spacer domains may considerably narrow the functionally important regions responsible for the excision event.

Adenosine Triphosphatases↗

PubMed1993

Alterations in [3H]-kainate receptor binding in the hippocampal formation of aged Long-Evans rats.

The present study used in vitro autoradiography to examine the density of [3H]-kainate (KA) binding in subregions of the hippocampal formation and certain cortical areas in young (7-8 months) and aged (27-29 months) Long-Evans rats. In addition, the topography of KA binding in the dentate molecular layer was examined for evidence of reactive reorganization in the aged brain. This investigation of age-related changes in [3H]-KA binding included correlations with the animals' spatial learning performance in a Morris water maze. The results showed an age-related decrease in the density of [3H]-KA binding in several regions of the hippocampal formation (CA3, CA1, hilus) and within related cortical areas (subicular complex, entorhinal cortex, perirhinal cortex). In addition, an expanded zone of KA binding in the molecular layer of the dentate gyrus was observed in the aged group. This expansion of KA binding may reflect sprouting due to a loss of perforant path input to the dentate. The results of additional correlational analyses, however, indicated that these changes in the density and topography of [3H]-KA binding were not strongly correlated with a decline in place learning ability.

Aging↗

PubMed1993

Effects of amygdala central nucleus lesions on blocking and unblocking.

The effects of lesions of the amygdala central nucleus (CN) on blocking and unblocking of appetitive Pavlovian conditioning were examined in 2 experiments with rats. In both lesioned and unlesioned rats, prior pairing of one conditioned stimulus (CS) with a food unconditioned stimulus (US) blocked the acquisition of conditioning to a second CS when a compound of both stimuli was paired with that same US. If the value of the US was increased or decreased when the second CS was added, unlesioned rats acquired substantial conditioning to the second cue (unblocking). Unblocking occurred in lesioned rats only when the US value was increased. In both lesioned and unlesioned rats, unblocking was prevented if the compound cue was paired with the original US prior to the change in US value. These data suggest that the CN is involved in increasing attention to signals for significant events but not in tuning out redundant cues.

Amygdala↗

PubMed1993

Amygdala central nucleus lesions disrupt increments, but not decrements, in conditioned stimulus processing.

The effects of neurotoxic lesions of the amygdala central nucleus (CN) on changes in the associability of a conditioned stimulus (CS) in appetitive Pavlovian conditioning were examined in 2 experiments with rats. In Experiment 1, CN lesions had no effect on the reduction in the associability of a CS produced by preexposure to that cue (latent inhibition). In Experiment 2, CN lesions prevented the enhancement of the associability of a CS that is normally observed when an inconsistent predictive relation is arranged between that CS and another cue. The results support previous claims that the amygdala CN is involved in broad-based incremental, but not decremental, changes in the processing of CSs in Pavlovian conditioning.

Amygdala↗

PubMed1993

Severity of spatial learning impairment in aging: development of a learning index for performance in the Morris water maze.

The Morris water maze task was originally designed to assess the rat's ability to learn to navigate to a specific location in a relatively large spatial environment. This article describes new measures that provide information about the spatial distribution of the rat's search during both training and probe trial performance. The basic new measure optimizes the use of computer tracking to identify the rat's position with respect to the target location. This proximity measure was found to be highly sensitive to age-related impairment in an assessment of young and aged male Long-Evans rats. Also described is the development of a learning index that provides a continuous, graded measure of the severity of age-related impairment in the task. An index of this type should be useful in correlational analyses with other neurobiological or behavioral measures for the study of individual differences in functional/biological decline in aging.

Aging↗

PubMed1993

The nominal group technique: a research tool for general practice?

Qualitative methods are increasingly recognized as valuable, yet practitioners face difficult decisions in their choice of method and the process of analysis. The nominal group technique combines quantitative and qualitative data collection in a group setting, and avoids problems of group dynamics associated with other group methods such as brainstorming, Delphi and focus groups. Idea generation and problem solving are combined in a structured group process, which encourages and enhances the participation of group members. The stages involved in conducting a nominal group are described, and practical problems of its use in a health care setting are discussed with reference to a study of the priorities of care of diabetic patients, carers and health professionals. Some potential applications of the technique in audit and exploratory research are also outlined.

Data Collection↗

PubMed1993

Delta hepatitis: molecular biology and clinical and epidemiological features.

Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection.

Animals↗

PubMed1993

Temperature-guided radiofrequency catheter ablation with very large distal electrodes.

BACKGROUND: Previous studies have shown that the size of lesions produced by radiofrequency catheter ablation correlates with the temperature and surface area of the electrode-tissue interface. The purpose of the present study was to compare the effects of ablation using very large distal electrodes (8F, 8 and 12 mm long) with those made by a conventional radiofrequency ablation catheter (distal electrode 8F, 4 mm long). METHODS AND RESULTS: Each catheter had a thermistor in the tip of the distal electrode. Radiofrequency energy (500 kHz) was supplied by a generator that continuously monitored temperature and produced up to 100 W. In 10 dogs, each of the three ablation catheters were introduced percutaneously and positioned under fluoroscopic guidance at disparate left ventricular endocardial sites. Radiofrequency power output was titrated to achieve a temperature of 80 degrees C for 60 seconds at each ablation site. The power required to produce a steady-state temperature of 80 degrees C was directly proportional to electrode size (15 +/- 7, 46 +/- 15, and 62 +/- 32 W using the 4-mm-, 8-mm-, and 12-mm-long electrodes, respectively). Lesions produced by the 8-mm electrode were nearly twice as deep (11 +/- 2.4 versus 6 +/- 1.2 mm, P < .001) and four times as large (905 +/- 410 versus 210 +/- 100 mm3, P < .001) as those made with a conventional 4-mm electrode. Lesions produced by the 12-mm electrode were intermediate in size (depth, 8 +/- 1.2 mm; volume, 465 +/- 225 mm3) and sometimes were associated with charring and crater formation. Ablation with the larger electrodes caused a drop in arterial pressure and more ventricular ectopy than ablation using a 4-mm distal electrode. CONCLUSIONS: Thermistor-equipped elongated ablation electrodes coupled to high-power outputs can reproducibly produce lesions approximately 1 cm in diameter. This system may prove useful for ablation of ventricular tachycardias in patients with coronary artery disease.

Animals↗

PubMed1992

Relaxation therapy as an adjunct in radiation oncology.

Stress, anxiety, and depression in patients who are undergoing treatment of cancer significantly compromise the quality of their lives. The impact of stress reduction by relaxation training and imagery was studied in 82 out-patients who were undergoing curative (73 patients) or palliative (9 patients) radiotherapy. Fifty-two females and 30 males were assigned randomly to a relaxation training condition (34 patients) as an adjunct to radiation or a control condition (29 patients), which entailed education and counseling along with the RT. Using pre- and posttests of the Profile of Mood States, significant (p less than .01) reductions were noted in the treatment group in tension, depression, anger, and fatigue. The results suggest that relaxation training substantially improves several psychological parameters associated with quality of life in ambulatory patients who are undergoing radiation therapy.

Adult↗

PubMed1992

Preserved configural learning and spatial learning impairment in rats with hippocampal damage.

This study was undertaken to compare the effect of hippocampal neurotoxic lesions in rats on two behavioral tasks, one a test of spatial learning, and the other an operant discrimination task that is acquired by forming nonspatial configural associations. Lesions of the hippocampus were made with microinjections of ibotenic acid. After postoperative recovery, rats were trained initially to locate a camouflaged escape platform in a water maze using distal spatial cues. Rats also were trained in the maze apparatus with a visible escape platform under conditions in which spatial information was made irrelevant to performance, i.e., cue learning. In an operant task, the same rats were then trained on a discrimination that included simultaneous feature positive and feature negative components (trial types XA+, A-, XB-, B+). After completion of this nonspatial configural learning task, rats received additional training in the water maze using a new platform location for spatial learning. To the extent that proficient performance in both the maze and operant tasks depends on a common function of the hippocampus, i.e., configural learning, the expectation was that hippocampal lesions would prove equally detrimental to performance in both tasks. Contrary to this expectation, lesioned rats were severely impaired in spatial learning but readily acquired the operant discrimination, even exhibiting some evidence of enhanced performance on this nonspatial configural learning task. Performance of the lesioned rats during cue training in the water maze was also enhanced relative to the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1992

Effects of aging on the diurnal pattern of water intake in rats.

This study was undertaken to confirm previous findings that Long-Evans rats exhibit age-related changes in the diurnal/nocturnal distribution of water intake and to examine the circadian pattern of these age-related changes. Twenty-one aged and 10 young pathogen-free rats were continuously monitored for water consumption over 12:12 h light/dark cycles. ANOVA, profile analysis, and cosinor analysis each demonstrated that aged rats differed from young rats. The age-related changes in circadian pattern can be described as a blunted rhythm (decreased amplitude) and an altered timing of peak activity (advanced acrophase). These differences, however, were only apparent in a subset of aged rats with the remaining aged rats exhibiting a circadian pattern indistinguishable from that of the young group.

Aging↗

PubMed1992

Public expenditures and health care in Africa.

Unfavorable economic conditions in most of Africa (in this paper Africa refers to Sub-Saharan Africa only) have meant public austerity and a deceleration in government health spending. Given the dominant role of government in providing health services in Africa there is a need to investigate the links between public spending and the provision of health care. Analyzing information from five Sub-Saharan African countries, namely Botswana, Burkina Faso, Cameroon, Ethiopia and Senegal, we investigate the impacts of shifting expenditure patterns and levels on the process of providing health services as well as on delivery of health care. The country analyses indicate that in addition to the level of public spending, the expenditure mix (i.e. salaries, drugs, supplies etc.), the composition of the health infrastructure (hospitals, clinics, health posts etc.), community efforts, and the availability of private health care all influence health care delivery. Consequently, per capita public expenditure (the most important indicator in a number of related studies) alone as a measure of the availability of health care and especially for cross-country comparisons is inadequate. Reductions in government resources for health care often result in less efficient mixing of resources and hence less health care delivery, in quality and quantity terms. With the recent trends in health care spending in Africa there should be greater effort to increase the efficient use of these increasingly scarce resources, yet the trend in resource mix has been in the opposite direction. Given the input to public health care of local communities, as well as the provision of private health care, it would seem that government spending on health care should be counter-cyclical, i.e. government health spending should accelerate during periods of economic down turns. Such counter-cyclical spending would tend to offset the difficulties facing local communities and the declining ability of individuals to pay for private health care. Recommending counter-cyclical health spending may seem wishful, but it points up the necessity of understanding what is likely to happen to health care in African countries in the face of economic difficulties, and particularly in the face of fiscal austerity.

Botswana↗

PubMed1992

Taste-potentiated odor aversion learning: role of the amygdaloid basolateral complex and central nucleus.

The present study examined the relative contributions of the amygdaloid basolateral complex (ABL) and central nucleus (CN) to taste-potentiated odor aversion (TPOA) learning--an associative learning task that is dependent on information processing in two sensory modalities. In Experiment 1, rats with neurotoxic lesions of these systems were trained on the TPOA task by presenting a compound taste-odor conditioned stimulus, which was followed by LiCl administration. Results showed that ABL damage caused an impairment in potentiated odor aversion learning but no deficit in the conditioned taste aversion. In contrast, rats with CN damage learned both tasks. Experiment 2 examined the effects of ABL damage on TPOA and odor discrimination learning. The odor discrimination procedure used a place preference task to demonstrate normal processing of olfactory information. Results indicated that although ABL-lesioned animals were impaired on TPOA, there was no deficit in odor discrimination learning.

Animals↗

PubMed1992

N-methyl-D-aspartate antagonist D-APV selectively disrupts taste-potentiated odor aversion learning.

Two experiments examined the effects of the competitive N-methyl-D-aspartate (NMDA) antagonist D-APV (D-2-amino-5-phosphonovalerate) on rats' ability to acquire potentiated aversions to the odor element of a taste-odor compound. In Experiment 1, pretreatment with D-APV (2.5 micrograms/side icv) caused stereospecific deficits in potentiated odor aversion learning but left simple taste and odor aversion learning intact. In Experiment 2, pretreatment with D-APV had no effect on rats' acquisition of an illness-based odor discrimination task. These results parallel those previously obtained using a noncompetitive NMDA antagonist (Robinson, Crooks, Shinkman, & Gallagher, 1989) and show that interference with NMDA receptors can selectively impair potentiated odor aversion learning. These results suggest that NMDA receptors play a critical role in some, but not all, forms of learning and memory.

2-Amino-5-phosphonovalerate↗

PubMed1991

Decreased glutamate release correlates with elevated dynorphin content in the hippocampus of aged rats with spatial learning deficits.

The effects of aging on extracellular glutamate and tissue dynorphin content in the hippocampus were examined in Fischer-344 rats. Young adult (4-month-old) and aged (24-month-old) rats were trained to find a hidden platform in the Morris water task. Aged rats were unable to acquire the spatial learning task as rapidly as young controls. Following behavioral testing, an in vivo microdialysis perfusion method was used to determine extracellular glutamate levels in the hippocampus. There was a 25-35% reduction in extracellular glutamate concentration in both dorsal and ventral hippocampus of aged rats compared to young rats, in the absence of any change in tissue glutamate levels. Radioimmunoassay showed an increase in dynorphin A(1-8)-like immunoreactivity [DYN-A(1-8)LI] in both dorsal and ventral hippocampus, but not striatum, of aged rats. Immunocytochemistry indicated that this increase was localized to the dentate granule cells and mossy fibers. Furthermore, among the aged rats the increase in DYN-A(1-8)LI was inversely correlated with the decrease in extracellular glutamate. These results suggest that the disregulation of dynorphin observed in cognitively impaired aged rats is related to reduced excitatory transmission within the hippocampal formation.

Aging↗