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Biomedical subjects

J M Fry

Publications and source records attributed to J M Fry.

At least 19 recordsLinked to original sources
PubMed1995

Inspiratory fall in systolic pressure in normal and asthmatic subjects.

We used a noninvasive monitor of arterial pressure to determine whether respiratory changes in arterial pressure were closely correlated with airflow obstruction in asthmatic patients during bronchial challenge with methacholine. To validate the noninvasive measurement of respiratory changes in arterial pressure, a preliminary study in 6 subjects with normal cardiovascular and respiratory systems was done during cardiac catheterization for suspected coronary artery disease. There were no significant differences between inspiratory falls in systolic pressure measured noninvasively and those measured from intraaortic pressure. In 11 otherwise healthy asthmatic patients we measured finger arterial pressure, end-expiratory lung volume (FRC), and forced expired volume (FEV1) during baseline and bronchial challenge in the supine posture. Finger arterial pressure was also measured in 11 normal control subjects seated and supine. Normal subjects had an inspiratory fall in systolic pressure (IFSP) of 3.2 mm Hg supine and 5.1 mm Hg seated (p < 0.01). Asthmatic patients when bronchodilated (seated FEV1 = 83 +/- 7% of predicted) had an IFSP of 5.9 mm Hg supine (p < 0.01 compared with supine normal subjects). During bronchial challenge (average fall in FEV1 = 22%), IFSP increased to 16.1 mm Hg (p < 0.001 compared with baseline). In asthmatic subjects, there was a significant correlation between IFSP and FEV1 (mean r = -0.92 +/- 0.05, p < 0.01), and the average change in IFSP/change in FEV1 was -0.38 mm Hg per percentage change in FEV1. During subsequent bronchodilation, IFSP decreased with a similar time course as relaxation of airway smooth muscle, assessed by the breath-to-breath fall in FRC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Plasma indicators of muscle damage in a model of nutritional myopathy in weaner sheep.

Subclinical nutritional myopathy was induced in 5-month-old sheep by feeding them a diet low in vitamin E and selenium. Subsequently clinical myopathy was induced by dosing with protected polyunsaturated fatty acids. Plasma activities of creatine kinase (CK), pyruvate kinase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase and aldolase, enzymes of muscle origin, all remained above their reference ranges in clinically affected sheep, but fluctuated widely. Similar fluctuations occurred in subclinically affected animals, resulting in some activities being within the reference ranges and some above, at different times. Plasma malondialdehyde, an indicator of lipid peroxidation, proved of no diagnostic value. Terminal plasma CK activities were significantly correlated with microscopic damage in the vastus lateralis (VL), but not the vastus intermedius (VI) or the tensor fascia lata (TFL) muscles. AST was the most highly correlated with damage in VI and VL. In two clinically affected sheep successfully treated with an oral dose of alpha-tocopherol acetate all enzymes decreased steadily to within their reference ranges, at rates probably related to their plasma half-lives. These results suggest that measurement of plasma CK activity would be useful in monitoring recovery of treated sheep.

Animals↗
PubMed1994

Muscle enzymes in the diagnosis of ovine weaner nutritional myopathy.

The diagnostic performance of plasma tests for muscle enzymes was measured in sheep from flocks affected by clinical and sub-clinical nutritional myopathy. Parallel combinations of tests for creatine kinase (CK), alanine amino transferase (ALT), aspartate amino transferase (AST) and lactate dehydrogenase had higher diagnostic sensitivity than CK alone. The enzymes ALT and AST showed the highest correlation with the degree of muscle damage. A parallel combination of tests for plasma CK and ALT as well as tests for plasma alpha-tocopherol and red cell glutathione peroxidase are recommended for the diagnosis of nutritional myopathy and a decision on the appropriate treatment. The number of false negative results based on a diagnosis from the microscopic examination of single muscles was higher than for the parallel combination of tests. The number of false negatives was highest for the vastus intermedius and lowest for the tensor fascia lata. Diagnosis using a panel of blood tests has the advantages of overcoming problems of inadequate muscle sampling, a larger number of sheep in the flock can be tested and a more rapid diagnosis can be obtained.

Alanine Transaminase↗
PubMed1994

Pediatricians and sleep disorders: training and practice.

OBJECTIVE: A series of studies were conducted to investigate pediatricians' training, knowledge, and practices regarding sleep and sleep disorders in children and adolescents. METHOD AND RESULTS: Study 1, a national survey of 156 pediatric residency programs, found that pediatricians receive a mean of 4.8 hours of instruction on sleep and sleep disorders, although the mode and median hours of instruction is 0 hours. In study 2, 88 pediatricians completing a questionnaire concerning general knowledge about sleep disorders in children and adolescents received a mean score of 71.8% (range, 40% to 93%). Pediatricians appear to know the most about developmental issues and sleep hygiene and the least about specific disorders such as narcolepsy and parasomnias. In the third study, 183 pediatricians were surveyed about their actual beliefs and practices regarding young children's sleep problems. Together, those surveyed reported that approximately 25% of their patients experience some type of sleep problem. Most pediatricians recommend behavioral interventions, although 14.8% of pediatricians report prescribing pharmacological treatments, and 48.9% inform parents that their child is likely to outgrow the problem. CONCLUSIONS: The results of these studies support the need for more education in sleep and sleep disorders in children and adolescents within medical schools, pediatric residency programs, and the practicing pediatric community.

Adolescent↗
PubMed1993

Plasma and tissue concentrations of alpha-tocopherol during vitamin E depletion in sheep.

To determine the relationship between plasma and tissue alpha-tocopherol concentrations during vitamin E depletion, weaned lambs were placed on a vitamin E-deficient diet for 0, 1, 2, 4, 8 and 12 weeks. alpha-Tocopherol was measured in plasma, erythrocytes, liver, adrenal, adipose tissue, three different skeletal muscles and heart muscle. The alpha-tocopherol concentration in plasma fell at the same rate as the alpha-tocopherol concentration in skeletal muscles, heart muscle, adrenal and adipose tissue. The alpha-tocopherol concentration in liver and erythrocytes fell at a faster rate than that of plasma and all muscle tissues. There were significant correlations between alpha-tocopherol concentration in plasma and alpha-tocopherol concentrations in all the tissues measured. Different skeletal muscles had significantly different concentrations of alpha-tocopherol which may relate to their differing susceptibility to nutritional myopathy. The increase in malondialdehyde in oxidatively-stressed muscle tissue and the correlation with alpha-tocopherol concentration in most muscle tissues indicated that the muscles had reduced antioxidant capacity in vitro as a result of vitamin E depletion. It was concluded that during vitamin E depletion in sheep alpha-tocopherol concentration in plasma was a good index of vitamin E status under the experimental conditions employed.

Adipose Tissue↗
PubMed1993

Repetitive nocturnal arterial oxygen desaturation and silent myocardial ischemia in patients presenting for vascular surgery.

OBJECTIVE: To determine whether nocturnal respiratory abnormality (cyclic oxygen desaturation and tachycardia) is associated with nocturnal myocardial ischemia in older individuals with ischemic heart disease. DESIGN: Non-invasive monitoring on a single occasion. SETTING: Tertiary care referral hospital. PATIENTS: Thirty four consecutive older (68.5 +/- 6 yrs) patients referred for elective abdominal or carotid reconstructive vascular surgery. RESULTS: Seven patients (21%) had moderately severe nocturnal respiratory abnormality, defined by more than 50 dips in arterial oxygen saturation and increases in heart rate during the night. Two of these seven had clinical risk factors for ischemic heart disease and had nocturnal myocardial ischemia. Ten patients (29%) developed ischemia at some time during the study, of whom seven hand known ischemic heart disease, hypertension, and/or angina. Those with increased nocturnal ischemia showed very low frequency (1-2 cycles per minute) cyclic heart rate oscillations and repetitive nocturnal episodes of arterial oxygen desaturation, similar to patients with sleep apnea. CONCLUSION: Repetitive nocturnal cyclic arterial desaturation and cyclic increases in heart rate are associated with nocturnal myocardial ischemia in individuals with clinical risk factors for ischemic heart disease. Further investigation in a large patient sample utilizing non-invasive monitoring of saturation, heart rate, and blood pressure may provide definitive evidence regarding causation of some of the nocturnal myocardial ischemia occurring in older individuals with vascular disease.

Aged↗
PubMed1989

Mitochondrial encephalomyopathy with corticosteroid dependence.

A 12-year-old boy with corticosteroid-responsive mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is described. His mother proved to have an asymptomatic mitochondrial myopathy on examination of a muscle biopsy specimen. Three weeks after the onset of vomiting, headache, ataxia and visual and speech impairment, he presented with a background of somatic growth retardation, deafness and school failure. Examination revealed disorientation, dysphasia, dyspraxia, optic atrophy, hemianopia, hemiparesis and sensory inattention. A cranial computed tomographic scan disclosed a large, low-density area, which was consistent with infarction, in the left posterior hemisphere and marked calcification of the basal ganglia bilaterally. Within two weeks of the commencement of corticosteroid treatment, the neurological dysfunction resolved. Attempts to decrease the dosage of dexamethasone caused an exacerbation of symptoms repeatedly. Two weeks after ceasing corticosteroid therapy, the patient developed a serious neurological relapse and a new, large, low-density area, which resembled an infarction, in the right posterior hemisphere on a computed tomographic scan. The reintroduction of corticosteroid therapy again resulted in the rapid resolution of all symptoms. It became evident that the patient had an exquisitely sensitive corticosteroid dependency, whereby a reduction in the dexamethasone dosage of even 0.25 mg a day caused confusion, headaches and increasing lactic acidaemia. Although it is difficult to assess the impact of various therapies in MELAS because of the episodic natural course of the disease, this remarkable corticosteroid responsiveness also has been noted in four previously reported patients with MELAS syndrome; therefore, it would seem reasonable to suggest that corticosteroid therapy now should be considered as standard treatment for this condition. However, corticosteroid therapy in other forms of mitochondrial disorders still awaits careful evaluation.

Acidosis, Lactic↗
PubMed1989

Avoiding false positive findings in measuring nocturnal penile tumescence.

The measurement and interpretation of nocturnal penile tumescence (NPT) studies depend on appropriate measurement techniques, knowledge of the conditions during which NPT was recorded, and a lack of preconceived notions about the relationship of penile circumference to penile rigidity. This case report illustrates several of the most common problems in the measurement and interpretation of NPT that could result in a false positive finding.

Aged↗
PubMed1989

Relationship of autonomic nervous system activity to daytime sleepiness and prior sleep.

Autonomic nervous system (ANS) measures have been used frequently as measures of activation or arousal. However, their relationship to standard measures of alertness--the Multiple Sleep Latency Test (MSLT) and Stanford Sleepiness Scale (SSS)--and to the quantity and quality of prior sleep has not been determined. In this study, the direct pupil light reflex (PLR) was measured with the MSLT and SSS to determine how ANS activity varies with daytime sleepiness and how all three measures were related to prior nocturnal sleep in a group of patients with obstructive sleep apnea. When the effects of age and time of day were partialed out, PLR data suggest that increased sleepiness as measured by MSLT is significantly correlated with increased parasympathetic activity (r = -0.60, p less than 0.01) and not with decreased sympathetic activity (r = -0.24, not significant). These partial correlations were significantly different (p less than 0.05). Increased sleepiness as measured by the SSS was significantly correlated with decreased sympathetic activity (r = -0.46, p less than 0.05) and not with increased parasympathetic activity (r = -0.00, not significant). These partial correlations were significantly different (p less than 0.02). In the group of sleep apnea patients, the PLR suggests that increased number of apneas and hypopneas (sleep fragmentation) was significantly correlated with both decreased sympathetic activity and increased parasympathetic activity. These findings suggest that ANS activity is related to daytime sleepiness and to the quality of prior sleep.

Arousal↗
PubMed1989

Periodic leg movements in sleep following treatment of obstructive sleep apnea with nasal continuous positive airway pressure.

Periodic leg movements in sleep are shown to be a common finding in patients with OSA and may become evident or increase in severity after treatment of the OSA with NCPAP. Periodic leg movements in sleep were measured during baseline polysomnography, a NCPAP treatment trial, and a repeat NCPAP recording in 33 patients treated with NCPAP for OSA. During baseline PSG, nine patients had five or more PLMS per hour of sleep (index), while 14 patients had a PLMSI of 5 or more during the NCPAP trial and the repeat NCPAP recording. Among those patients with a PLMSI of 5 or more during repeat NCPAP studies, the PLMSI showed a significant increase from baseline to initial NCPAP (16.9 +/- 25.3 vs 39.3 +/- 29.4; p less than 0.001) and from baseline to repeat NCPAP (16.9 +/- 25.3 vs 42.9 +/- 39.8; p less than 0.05). The number of PLMS associated with electroencephalographic arousal also increased significantly from baseline to initial NCPAP (4.3 +/- 7.4 vs 9.7 +/- 8.9; p less than 0.05) and from baseline to repeat NCPAP (4.3 +/- 7.4 vs 16.5 +/- 18.6; p less than 0.05). The 14 patients with a PLMSI of 5 or more on the repeat NCPAP had significantly more stage 1 sleep and less REM sleep than 19 patients with a PLMSI of less than 5. Bilateral anterior tibialis EMG must be measured during NCPAP recordings in order to recognize sleep disruption caused by PLMS.

Electroencephalography↗
PubMed1988

What is normal sleep in the elderly?

Changes in the sleep and daytime alertness of the elderly are common and are secondary to a variety of causes. These changes cannot be attributed solely to the aging process. The role of occult sleep disorders in producing these changes in significant, and severe sleep disruption in the healthy elderly is almost always secondary to a sleep disorder such as sleep apnea. A number of precautions must be kept in mind when interpreting studies of sleep in the elderly.

Aged↗
PubMed1987

Sleep disorders.

Advancements in sleep research have led to the development of new standards of what is normal sleep and arousal and new diagnostic tests for the detection of sleep disorders. Millions of adults have frequent or chronic complaints about the quality and quantity of their sleep. Sleep complaints increase with increasing age and are more common in women than in men and in women over 45 than in younger women. Sedative-hypnotic drugs are taken more frequently by women than men, and the incidence of use increases with increasing age. Studies of sleep and sleep disturbances during the perimenopausal period suggest that difficulty falling asleep and frequent nocturnal awakenings result from hormonal changes, vasomotor symptoms, and possibly psychologic factors. Other causes for sleep complaints in menopausal and postmenopausal women are occult sleep disorders, especially periodic leg movements in sleep and sleep apnea syndrome. Sleeping pills are inappropriate for most patients with sleep complaints. If sleep difficulties persist after a trial of good sleep hygiene, further evaluation at a sleep disorders center is indicated.

Aging↗
PubMed1986

Problems in the interpretation of nocturnal penile tumescence studies: disruption of sleep by occult sleep disorders.

A review of the sleep of 31 patients 45 years old or older undergoing nocturnal penile tumescence studies showed that 19 had a previously undiagnosed sleep disorder. Of the patients 9 had periodic leg movements in sleep, 9 had sleep apnea and 1 had both disorders. In 10 of these patients the sleep disorders affected nocturnal penile tumescence by disrupting sleep and causing brief periods of detumescence, movement artifacts and delays in the tumescing phase of nocturnal penile tumescence. These disruptions resulted in an apparently abnormal nocturnal penile tumescence that appeared as if the patient had difficulty in achieving or maintaining an erection. The nocturnal penile tumescence disruptions may have reflected only a disruption of the necessary conditions for normal nocturnal penile tumescence to occur, namely adequate sleep and rapid eye movement sleep. The results strongly suggest that failure to measure concurrent sleep parameters and screen for occult sleep disorders could result in the incorrect diagnosis of abnormal nocturnal penile tumescence.

Aged↗
PubMed1986

Senile miosis: the possible contribution of disordered sleep and daytime sleepiness.

The contribution of disordered sleep and daytime sleepiness to senile miosis was investigated in 23 participants aged 60 to 80 years and 12 participants aged 21 to 40 years. All participants filled out questionnaires and were interviewed about their health, sleep, and daytime alertness. On this basis the older group was subdivided into a group of 13 participants with sleep disorders or daytime sleepiness and 10 participants without. All participants were studied with a computerized infrared television pupillometry system for 15 s in ambient lighting, 15 s after 5 min dark adaptation and with 5 light flashes. Pupil diameter after dark adaptation was significantly larger in the older group without sleep disorders than in the older group with sleep disorders (5.94 +/- .73 mm vs. 4.49 +/- .62 mm, M +/- SD, p less than .001). Significant partial correlation coefficients controlled for age were found between pupillary diameter and a variety of sleep variables. The data suggest that occult sleep disorders and daytime sleepiness may contribute to senile miosis.

Adult↗
PubMed1986

Treatment of narcolepsy with codeine.

The effectiveness of codeine as a treatment for the excessive daytime sleepiness of narcolepsy was studied in two experimental trials. In an open trial of codeine in five narcoleptic subjects, dramatic clinical improvement was reported. However, all-night polysomnography and maintenance of wakefulness tests before and after codeine showed no significant differences. A double-blind placebo-codeine trial was conducted in which eight narcoleptic subjects received codeine for 1 week and placebo for 1 week in a random order. During the week they kept a diary, and on the sixth evening and for 10 h following awakening on the seventh day they were monitored by radiotelemetry in the sleep laboratory for electroencephalogram, electro-oculogram, and electromyogram. The results were analyzed for sleep stages as well as four levels of wakefulness. The results showed no significant differences in any of the objective sleep or wakefulness parameters. However, the diaries showed significantly fewer naps during the week on codeine as compared with the placebo week. Eighteen of 27 narcoleptic patients treated with codeine report clinical improvement. Codeine consistently results in subjective clinical improvement. However, this is not reflected in the objective measures generally used to assess daytime sleepiness.

Adult↗
PubMed1986

Effects of low-dose naloxone on subjective alertness and pupil diameter in normal and narcoleptic subjects.

Recent evidence suggests that endogenous opiates may be involved in the pathophysiology of narcolepsy. To test this theory, the effect of 0.8 mg naloxone hydrochloride on pupil size and subjective alertness was measured in normal and narcoleptic subjects. Naloxone resulted in significant pupillary constriction in the normal but not in the narcoleptic subjects. The extent of contraction of the pupil light reflex was reduced significantly in the narcoleptic but not in the normal subjects. There was no effect on subjective ratings of alertness on the Stanford Sleepiness Scale or the visual analogue scale in either group. The naloxone-related miosis in the normal group confirms that naloxone is not a pure opiate antagonist. The lack of naloxone-related miosis in the narcoleptics suggests that narcoleptic individuals do not respond to naloxone as do normal individuals. However, this difference can not be definitely attributed to the antagonism of endogenous opiates. The reduction of the extent of contraction of the light reflex suggests that naloxone caused an increase in supranuclear inhibition of parasympathetic pupil reflex activity. However, this finding may have resulted from mechanical limitations of a small pupil or technical limitations of the recording equipment. This study does not support previous reports that naloxone causes an increase in subjective alertness in narcoleptics.

Adult↗