Biomedical subjects

R A Swain

Publications and source records attributed to R A Swain.

At least 19 recordsLinked to original sources

PubMed1997

Learning-dependent dendritic hypertrophy of cerebellar stellate cells: plasticity of local circuit neurons.

Recent work has shown that motor learning, but not mere motor activity, changes the morphology of Purkinje cells, the major projection neurons of the cerebellar cortex. In the present study we examined how motor skill learning affects the dendritic morphology of the stellate local circuit neurons. Adult female rats were either trained to complete a complex motor learning task or forced to traverse a flat, obstacle-free runway. Golgi impregnated stellate cells were then traced via camera lucida and their dendritic arborizations examined with a concentric ring analysis. Results showed the motor learning animals to have significantly greater stellate cell dendritic arborizations than the activity controls. Thus these local circuit neurons exhibit morphological plasticity.

Animals↗

PubMed1997

Diagnosis, prophylaxis, and treatment of headaches in the athlete.

BACKGROUND: Headaches are a common entity in the ambulatory population. Physicians involved in sports medicine must be able to accurately diagnose headaches in athletes and whether they are exacerbated by exertion. Many medications have proven or theoretical negative effects on athletic performance. Thus, we should consider all aspects of medical management and determine which therapy is least intrusive to the athlete's performance. We planned this review because of the small number of papers available on the effects of various medications on athletic performance. METHODS: We used MEDLINE to search from 1992 to current citations, using the medical subject headings of headache, prophylaxis, treatment, review, athletes, and exercise, alone or in combination. RESULTS: Fifty-two articles were identified and deemed appropriate for inclusion in this review. CONCLUSIONS: Acute therapy for tension headaches in the athletic population is best done with nonsteroidal anti-inflammatory drugs. Prophylaxis of chronic, recurrent tension headaches is best accomplished by night-time tricyclic antidepressants (especially nortriptyline) or selective serotonin reuptake inhibitors. Acute therapy for athletes with migraines is best managed with sumatriptan or DHE 45 and prophylaxis can be accomplished with verapamil, antidepressants, or valproate. Exertional, cluster, and structural/infectious headaches are also discussed briefly.

Analgesics, Non-Narcotic↗

PubMed1997

Do pseudoephedrine or phenylpropanolamine improve maximum oxygen uptake and time to exhaustion?

OBJECTIVE: To study the effects of over-the-counter dosages of the pure alpha 1-agonists pseudoephedrine (PSE) and phenylpropanolamine (PPA) on selected parameters of exercise performance, and to establish a range of corresponding drug levels in the urine of the athletes who use these drugs. DESIGN: Placebo-controlled, randomized, double-blinded, multiple-dose trial. SETTING: The National Institute of Fitness and Sport, the Department of Family Medicine, Indiana University, and the Sports Medicine Lab, Department of Pathology, Indiana University, Indianapolis, Indiana. PARTICIPANTS: A convenience sample of 20 male cyclists, aged 18-35, from the local cycling community. Inclusion criteria required cycling at least 50 miles a week, no chronic medical problems, and not taking any medications. Subjects were recruited by local ads and word of mouth. INTERVENTION: Patients were randomized to one of two groups of 10 subjects. Each subject in both groups performed three separate bicycle ergometer tests after ingestion of varying dosages of alpha 1-agonists. One group performed tests after receiving placebo, 0.33 mg/kg PPA, and 0.66 mg/kg PPA, whereas the other group received placebo, 1 mg/kg PSE, and 2 mg/kg PSE. A minimum 1-week washout period was required between tests. Urine for drug testing was collected 1 h before, immediately afterward, and the next morning after testing. Drug testing was performed by gas GC/MCD at a facility approved by the International Olympic Committee. MAIN OUTCOME MEASURES: Maximum oxygen uptake (VO2max), time to exhaustion, urine drug levels of PSE and PPA, peak blood pressures (BPs), peak pulse, and Borg scale (rating of perceived exertion or RPE). MAIN RESULTS: In the PPA group, the 0.33-mg/kg dose resulted in insignificant changes in peak systolic BP (+5.4 mm Hg, p = 0.260), peak diastolic BP (-1.6 mm Hg, p = 0.622), peak pulse (-2.2 beats/min, p = 0.12), peak Borg (RPE = -0.10 (p = 0.823), time to exhaustion (-16.9 s, p = 0.287), and VO2max (+0.50 ml/kg/min, p = 0.71). No significant change was noted in any study variable at the 0.66-mg/kg PPA dose, and some effects were dissimilar to the lower PPA dose effects. Peak systolic BP increased 2.8 mm Hg (p = 0.617), diastolic BP decreased 1.6 mm Hg (p = 0.634), peak pulse increased 1.4 beats/min (p = 0.504), peak Borg RPE decreased 0.80 (p = 0.210), time to exhaustion decreased 2.6 s (p = 0.861), and VO2max decreased 2.92 ml/kg/min (p = 0.14). In the 1-mg/kg PSE group, there was a significant increase in peak systolic BP (+10.6 mm Hg, p = 0.029). No significant changes occurred in peak diastolic BP (+2.4 mm Hg, p = 0.333), peak pulse (+2.2 beats/min, p = 0.306), peak RPE (+0.2, p = 0.62), time to exhaustion (+21.4 s, p = 0.289), and VO2max (+2.29 ml/kg/min, p = 0.31). In the 2-mg/kg PSE dose trial, there were insignificant changes in peak systolic BP of +2.4 mm Hg (p = 0.559), +3.8 mm Hg in peak diastolic BP (p = 0.106), +1.6 beats/min in peak pulse (p = 0.586), -0.1 in peak Borg RPE scales (p = 0.76), -10.4 s in time to exhaustion (p = 0.41), and +1.79 ml/kg/min in VO2max (p = 0.43). Urine drug levels in those subjects receiving 1 mg/kg PSE ranged from 7-55 micrograms/ml before performance and 30-128 micrograms/ ml after performance to 7-35 micrograms/ml the next morning. Levels in those receiving 2 mg/kg ranged from 5-160 micrograms/ml before performance and 44-200 micrograms/ml after performance to 8-44 micrograms/ ml the next day. In the PPA 0.33-mg/kg dose trials, the levels ranged 1-36 micrograms/ml before performance and 9-50 micrograms/ml after performance to < 1-14 micrograms/ml the next morning. In the PPA 0.66-mg/kg dose trials, the levels were 4-52 micrograms/ml before performance, 8-80 micrograms/ml after performance, and 6-74 micrograms/ml the next day. CONCLUSIONS: We found no significant differences between trials in maximum oxygen uptake (VO2max), peak or progression of Borg Scale (RPE), maximum systolic and diastolic BPs, peak pulse, or t

Adolescent↗

PubMed1997

The role of folic acid in deficiency states and prevention of disease.

Folic acid, a water-soluble vitamin, has been used since the 1940s to treat some cases of macrocytic anemia without neurologic disease. Folate deficiency is best diagnosed with red blood cell folate levels along with macrocytosis and/or megaloblastic anemia. In addition to reversing overt deficiency, the vitamin may reduce the incidence of neural tube defects by 45% in women who receive 400 micrograms per day. It is recommended that all women of childbearing age take 400 micrograms of folate per day. Elevations in homocysteine levels, a metabolite intimately associated with folate, are also being found with increasing regularity in those with cardiovascular diseases. Homocysteine levels are reduced by folic acid administration. Therefore, there is some biologic plausibility, but not currently direct proof, for the assumption that folate supplements may prevent heart disease, stroke, and peripheral arterial disease. Controlled trials should take place before widespread food supplementation with folate is carried out on a large scale because of the possibility of outbreaks of permanent B12-related neurologic damage in those with undiagnosed pernicious anemia. However, if a patient has a premature cardiovascular event and has minimal risk factors, ordering a test to determine homocysteine level may be advisable, and if elevated, treating with folic acid supplement as long as B12 deficiency does not coexist.

Anemia, Macrocytic↗

PubMed1996

Classical conditioning with electrical stimulation of cerebellum as both conditioned and unconditioned stimulus.

Stimulating electrodes were implanted in rabbit cerebellum, providing an electrical conditioned stimulus (CS) activating cortical parallel fibers and thence Purkinje and other cells, and an electrical unconditioned stimulus (US) activating underlying white matter and eliciting unconditioned responses. Paired CS-US presentations led to the development of conditioned responses, which showed extinction following CS-alone trials and reacquisition with significant savings on reinstatement of paired trials. Increased local excitability as a result of paired training (but not following unpaired stimulus presentations) was observed in cerebellar cortex, as manifested in substantial decreases in CS threshold for response elicitation in all subjects. This preparation offers a model for the study of plastic neuronal interactions within cerebellar networks critically involved in associative learning.

Animals↗

PubMed1996

The os acromiale: another cause of impingement.

Impingement of the shoulder is a relatively common clinical entity. The os acromiale anomaly is an uncommon one (1-8%) but can be an important cause of the impingement syndrome. The most common place of nonfusion is between the meso- and meta-acromion. The key to diagnosis is a history and physical examination compatible with the impingement syndrome and appropriate radiologic studies (i.e., an axillary view or profile view or computed tomographic scan if necessary). After diagnosis, the initial treatment is conservative with rest, ice, nonsteroidal anti-inflammatory drugs (NSAIDs), injections of corticosteroids in the subacromial space, and most importantly, an appropriate rehabilitation program. If unsuccessful, treatment should be planned based on the size of the unfused fragments. Small fragments (< 4 cm) may be removed by either arthroscopic or open means. Larger fragments may require an attempt at bone grafting and fixation since their removal may result in loss of strength of the deltoid.

Acromion↗

PubMed1996

Natural variability and diurnal fluctuations within the bacteriophage population of the rumen.

To investigate the impact of nutritional and environmental factors on bacteriophage activity in the rumen, it is first valuable to determine the extent of natural variations and fluctuations in phage populations from different animal species, and from animals located together and separately, and variation in animals over time. Differences in phage populations between sheep on different diets, between sheep and goats, and within the rumen over time were investigated by using pulsed-field gel electrophoresis and comparing total phage DNA in ruminal fluid. It was found that no two individuals had similar DNA banding patterns, even when similarly fed and penned together, indicating there is considerable individual diversity in phage populations between animals. Despite these individual differences, the quantities, but not the banding patterns, of phage DNA were similar for animals within groups but varied between groups, suggesting that nutritional factors may influence overall phage activity in the rumen. In sheep fed once daily, a distinct diurnal variation in the phage population was observed. Two hours postfeeding, total phage DNA dropped to its lowest level. The phage population then increased, reaching a maximal level 8 to 10 h postfeeding before declining over the next 4 h to reach a stable concentration for the rest of the cycle. The general trend in phage DNA concentration appeared similar to previously recorded diurnal fluctuations in ruminal bacterial populations in cattle fed once daily.

Animals↗

PubMed1996

Iron deficiency anemia. When is parenteral therapy warranted?

Iron deficiency anemia is a common problem encountered in primary care practice. Once the diagnosis is confirmed and the possible causes are identified, replacement of iron stores is indicated. Most patients respond favorably to oral iron preparations. However, therapy with intravenous iron dextran (InFeD) may be warranted in some cases. Side effects, which are usually mild, occur in 25% of patients. Test doses of undiluted iron dextran occasionally elicit anaphylactic reactions. However, affected patients still may be successfully treated intravenously with the use of prophylactic antihistamines, corticosteroids, and histamine2 blockers. Treatment of iron deficiency anemia almost always brings symptomatic improvement.

Adult↗

PubMed1995

Training room evaluation of chest pain in the adolescent athlete.

A physician or athletic trainer will often be faced with an athlete complaining of chest pain during or after an event. Chest pain in children and adolescents is usually of a noncardiac origin; only 5% of cases are due to cardiac problems. With a properly documented history and physical evaluation, one can usually identify the etiology of the chest discomfort or at least rule out any serious difficulties. The various diagnostic possibilities include cardiac, musculoskeletal, pulmonary, gastrointestinal, and psychiatric causes of pain. We discuss several specific conditions, as well as the signs, symptoms, and basic management.

Adolescent↗

PubMed1994

Parallel augmentation of hippocampal long-term potentiation, theta rhythm, and contextual fear conditioning in water-deprived rats.

The influence of water deprivation on hippocampal long-term potentiation (LTP), theta rhythm, and contextual fear conditioning in rats was examined. In Experiment 1, hippocampal EEG activity and perforant path LTP were assessed in pentobarbital-anesthetized rats. Water deprivation did not affect baseline cell excitability or low-frequency synaptic transmission in the dentate gyrus, but it increased the magnitude of perforant path LTP and elevated the proportion of theta rhythm in the EEG. In Experiment 2, rats were classically conditioned to fear a novel context through the use of aversive footshocks. Water deprivation facilitated the rate of contextual fear conditioning but did not alter the asymptote of learning. Experiment 3 demonstrated that the facilitation of contextual fear conditioning was not due to a change in unconditional shock sensitivity. These results suggest that water deprivation exerts an influence on contextual fear conditioning by modulating hippocampal LTP and theta rhythm and that these processes serve to encode contextual information during learning.

Animals↗

PubMed1994

Exercise-induced diarrhea: when to wonder.

Exercise-associated lower gastrointestinal symptoms seem to be a fairly common clinical finding occurring in anywhere from 10-50% of runners. However, it is unclear what percentage of those affected may have discrete medical conditions that are exacerbated by strenuous physical exertion. Perhaps, difficult physical training sessions function as a "stress test" for the colon. A case report of exercise induced diarrhea is presented with a discussion of the current medical literature and proposed management for the primary care sports physician.

Animals↗

PubMed1994

Topographical analysis of cortical evoked activity during a variable demand spatial processing task.

This experiment studied changes in brain activity as subjects performed a variable demand spatial rotation task. The task involved the sequential presentation of a template histogram and a spatially rotated comparison histogram. Task difficulty was manipulated by varying the number of bars and the degree of rotation. Topographical analysis of the brain event-related activity data indicated the presence of negative components that were maximal at the vertex within 80 ms and bilaterally in the temporal lobes within 140 ms of stimulus onset and that appeared to be insensitive to changes in task difficulty. Demand-sensitive potentials were recorded, however. Positive components corresponding to P200 and P300 activity were recorded symmetrically around site PZ. The P200 component declined in amplitude, but showed no changes in latency as task demand increased. P300 activity declined in both amplitude and latency as the task became more difficult. Finally, a positive component was recorded over right central cortex approximately 490 ms after stimulus onset. This component declined in amplitude but increased in latency as task difficulty increased.

Adult↗

PubMed1993

In search of engrams.

The body of literature presented in this paper indicate, as Marr and Albus hypothesized, that the cerebellum is involved in the regulation of classical conditioning. At present, the most parsimonious hypothesis is that the essential memory traces for classical conditioning of eyelid closure, limb flexion, and other discrete responses learned with an aversive US are formed in cerebellar cortex and interpositus nucleus. Both sites contain neuronal elements which encode both conditioned and unconditioned stimuli. Recordings from both cerebellar cortex and the deep nuclei model the topography of the conditioned response and precede the response in time. Lesions of the cortex massively impair conditioning and lesions of the interpositus nucleus completely and permanently abolish the conditioned response without affecting reflex performance.

Animals↗

PubMed1993

Hippocampal plasticity during jaw movement conditioning in the rabbit.

Hippocampal CA1 unit responses were recorded during classical conditioning of rhythmic jaw movements in New Zealand White rabbits. Training was accomplished using a 1 kHz tone as the conditioned stimulus (CS) and 1 ml of sweetened water as the unconditioned stimulus (US). The interstimulus interval was 250 ms. Daily sessions consisted of 48 paired trials and six tone alone test trials, with an intertrial interval averaging 60 s. Controls were given explicitly unpaired stimuli. Unit and behavioral conditioned responses developed very rapidly in the trained group, but did not occur in controls. Averaged unit poststimulus histograms showed a correspondence between rhythmic cell discharges and the periodicity of the behavioral conditioned response after training. The results are discussed in relation to a hippocampal role in the modulation of learned movement patterns.

Animals↗

PubMed1993

Ankle injuries. Tips from sports medicine physicians.

In dealing with an ankle sprain, worrisome features are few but important to recognize. A "pop" heard or felt at the time of injury, a prolonged course, or a history of several previous injuries are all of concern. Medial tenderness on palpation, positive results on a squeeze test, or markedly positive results on stress testing are also indicators of severe injuries, which may require referral for treatment. Stress testing by an experienced clinician is appropriate for chronic or severe cases. Otherwise, treatment of the acute, uncomplicated ankle injury is straightforward, focusing on early mobilization, rehabilitation, and protection.

Ankle Injuries↗

PubMed1993

NSAIDs. Are there any differences?

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most widely prescribed groups of medication in the United States. While the selection of the most appropriate NSAID should be based on therapeutic efficacy, adverse reaction profile, concurrent therapy, simplicity of dosage regimen, patient acceptance and compliance, cost, and the specific patient's medical profile, prescribing habits are often not based on specific guidelines. The choice of NSAID is further complicated by the wide variety of available agents; over 20 NSAIDs are presently available to the primary care physician. None of the NSAIDs is best for all of the criteria that are considered when selecting an NSAID; therefore, the physician needs to be able to determine which agent provides the desired benefits while outweighing the potential risks. This article provides a rational approach to prescribing NSAIDs in the primary health care setting.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1993

Estimation of ruminal bacteriophage numbers by pulsed-field gel electrophoresis and laser densitometry.

To investigate phage activity in the rumen, a method for quantifying phage has been developed. By differential centrifugation and ultrafiltration, phage particles were separated and concentrated from ruminal fluid. Linear double-stranded DNA from this fraction containing predominantly tailed phage was isolated and separated by size, using pulsed-field gel electrophoresis (PFGE). Laser densitometry of gel photographs allowed the numbers of phages with DNA in each size region to be calculated and, therefore, the total numbers per milliliter of ruminal fluid to be estimated. Phage numbers were estimated to be between 3 x 10(9) and 1.6 x 10(10) particles ml of ruminal fluid-1. The phage population, as gauged by the appearance of DNA on PFGE gels, had two major components. A broad region of DNA between 30 and 200 kb was always present on PFGE gels. It appears this region comprises DNA from a great many different phages and would include most of the temperate phages. In addition, discrete DNA bands ranging in size from 10 to 850 kb were frequently observed. DNA from one such band, of 12 kb in size, was shown to consist primarily of a single DNA type, suggesting that it originated from a specific phage. It is postulated that the discrete bands are due to epidemics or blooms of phage activity from specific, probably lytic, phages. The method that has been developed will greatly enhance future investigations into the interactions between the ruminal phage population, the ruminal bacterial population, and animal nutrition and growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Cerebellar stimulation as an unconditioned stimulus in classical conditioning.

Rabbits were implanted with chronic stimulating electrodes in white matter underlying lobule HVI of the cerebellar cortex. Stimulation elicited movements of the face or neck and, when paired with a tone conditioned stimulus (CS), produced learning comparable to that seen with peripheral unconditioned stimuli (USs). CS-alone trials produced extinction. Reinstatement of paired trials produced reacquisition with savings. Additional groups received either explicitly or randomly unpaired CS-US trials before paired conditioning. Low-frequency responding during these sessions indicated that the paired training results were associative and not due to pseudoconditioning or sensitization. Explicitly unpaired sessions retarded learning on subsequent paired trials compared with groups that received either randomly unpaired or no CS-US preexposure. These results are interpreted in terms of the role of the cerebellum and associated pathways in classical conditioning of motor responses.

Animals↗