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Biomedical subjects

J Perry

Publications and source records attributed to J Perry.

At least 91 records · Page 5Linked to original sources
PubMed1985

Turnover of the methyl moiety of 5-methyltetrahydropteroylglutamic acid in the cobalamin-inactivated rat.

The metabolism of the methyl group of 5-methyltetrahydrofolate was studied in rats in which cobalamin had been inactivated by exposure to nitrous oxide and in air-breathing control animals. Methylfolate labeled with [14C] in the methyl group and with [3H] in the pteridine-PABA portion was injected and the disappearance of [14C]H3- relative to [3H]folate was measured in liver. The half-time of the methyl group in the livers of control rats was two hours. There was no turnover of the methyl group for the first 72 hours after cobalamin inactivation. After 72 hours, there was a slow turnover of the methyl group, with a half-time of 43 hours. In control rats, it is assumed that the methyl group was metabolized by transfer to homocysteine to form methionine. In cobalamin-inactivated rats, it was shown that methylfolate was used as the substrate for forming folate polyglutamate, and analogues with 3, 4, and 5 glutamic acid residues were present. It is likely that oxidation of the methyl group by methylene tetrahydrofolate reductase occurs from folate polyglutamate containing six and seven glutamic acid residues, (Brody et al, Biochemistry 21: 276, 1982), since we were unable to demonstrate labeled methyl in longer chain analogues.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1984

Gait analysis techniques. Rancho Los Amigos Hospital gait laboratory.

In the gait laboratory at Rancho Los Amigos Hospital, the emphasis is on patient testing to identify functional problems and determine the effectiveness of treatment programs. Footswitch stride analysis, dynamic EMG, energy-cost measurements, force plate, and instrumented motion analysis are the techniques most often used. Stride data define the temporal and distance factors of gait. We use this information to classify the patient's ability to walk and measure response to treatment programs. Inappropriate muscle action in the patient disabled by an upper motor neuron lesion is identified with dynamic EMG. Intramuscular wire electrodes are used to differentiate the action of adjacent muscles. We use the information to localize the source of abnormal function so that selection of treatment procedures is more precise. Force and motion data aid in determining the functional requirement and the muscular response necessary to meet the demand. Determining the optimum mode of locomotion and developing criteria for program planning have become more realistic with the aid of energy-cost measurements. Microprocessors and personal computer systems have made compact and reliable single-concept instrumentation available for basic gait analysis in the standard clinical environment at a modest cost. The more elaborate composite systems, however, still require custom instrumentation and engineering support.

Adult↗
PubMed1984

Ankle and subtalar motion during gait in arthritic patients.

The purposes of this study were 1) to document ankle and subtalar motion during gait in 20 healthy subjects and in 25 patients with rheumatoid arthritis (RA) and 2) to determine stride characteristics with and without the use of an extended University of California Biomechanics Laboratory orthosis in RA patients with painful ankle and hindfoot deformity. An insole foot-switch system and ankle and subtalar electrogoniometers measured stride characteristics and dynamic range of motion (ROM). Arthritic patients demonstrated less ROM than healthy subjects except for ROM of hindfoot valgus. Arthritic patients also had slower gait velocity and less single limb support (SLS) time. In five new and five current orthotic wearers, a significant increase (p less than .01) in velocity and SLS time occurred with shoes and a further significant increase (p less than .01) occurred with the orthosis. Nine of 10 patients reported a decrease in ankle and hindfoot pain after using the orthosis. This study demonstrates the value of an orthosis for the treatment of arthritic patients with ankle and hindfoot pain and deformity.

Adult↗
PubMed1983

Effects of nitrous oxide-induced inactivation of cobalamin on methionine and S-adenosylmethionine metabolism in the rat.

Inhalation of nitrous oxidises cobalamin and, in turn, inactivates methionine synthetase which forms methionine from homocysteine and which requires cob[I]alamin as a co-factor. This study was planned to determine the effect of virtual cessation of methionine synthesis via a cobalamin-dependent pathway, on tissue levels of methionine, S-adenosylmethionine and on related enzymes. The level of methionine in liver fell initially after exposure to N2O but was restored to pre-N2O levels after 6 days despite continuing N2O exposure. Brain methionine fell within 12 h of N2O exposure but the fall was not significant. The restoration of methionine levels is accompanied by an increase in activity of betaine homocysteine methyltransferase in liver but this enzyme was not detected in brain. The activity of methionine synthetase remained very low in both liver and brain as long as N2O inhalation was continued. There was an initial rise in liver S-adenosylmethionine levels followed by a steady fall to 40% of its initial level after 11 days of N2O exposure. However, there was no change in the level of S-adenosylmethionine in brain during this period. The data indicate that either brain meets its requirement by increased methionine uptake from plasma or that there are alternate pathways in brain for methionine synthesis other than those requiring a cobalamin coenzyme.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1983

Effect of nitrous oxide-induced inactivation of vitamin B12 on glycinamide ribonucleotide transformylase and 5-amino-4-imidazole carboxamide transformylase.

Exposure to nitrous oxide (N2O) in vivo is accompanied by oxidation of cob[I]-alamin to the inactive cob[III]alamin [1]. There is loss of methionine synthetase activity [2] and evidence of depressed supply of single carbon units at the formate level of oxidation [3,4,5]. We measured the effect of inactivation of B12 on the folate-dependent transformylases concerned in purine synthesis. After 24 h exposure to N2O there was a significant fall in glycinamide ribonucleotide transformylase (EC 2.1.2.2) and a significant increase in 5-amino-4-imidazole carboxamide transformylase (EC 2.1.2.3).

Acyltransferases↗
PubMed1983

Increased urinary excretion of formiminoglutamic acid in nitrous-oxide-treated rats and its reduction by methionine.

Inhalation of nitrous oxide oxidises cob(I)alamin and inactivates methionine synthetase of which cobalamin is a co-enzyme. The biochemical changes in the rat following exposure to nitrous oxide resemble in some detail the changes present in patients with untreated pernicious anemia due to deficiency of cobalamin. There is a marked increase in the excretion of formiminoglutamic acid in the urine following exposure to nitrous oxide. A significant decrease is produced, while on N2O, by giving methionine. The explanation for these findings is discussed in the light of recent data on the effects of cobalamin inactivation.

Animals↗
PubMed1983

Comparative cost of walking in young and old adults.

Normative data that summarize the energy requirements and gait characteristics of level outdoor walking were determined in 111 normal subjects between the ages of 20 and 80 years. Subjects were divided into two age groups: young adults (20-59 years) and senior subjects (60-80 years). The mean rate of oxygen consumption for young adults and senior subjects did not significantly differ, averaging 11.9 ml/kg-min for both groups. The data on heart rate paralleled the findings on oxygen consumption, averaging 100 and 103 beats/min, respectively. The net oxygen cost per meter walked for senior subjects, 0.16 ml/kg-m, was significantly greater (p less than 0.0005) than the value for young adults, 0.15 ml/kg-m, due to a decline in the average walking speed. The average gait velocity for senior subjects, 73 m/min, was statistically significantly less (p less than 0.0005) than the values for the younger adults, 80 m/min.

Adult↗
PubMed1983

Timing and relative intensity of hip extensor and abductor muscle action during level and stair ambulation. An EMG study.

The timing and relative intensity of electromyographic activity of hip abductor and extensor muscles were recorded during free and fast velocity walking and during ascent and descent of stairs. Eleven healthy subjects were tested using fine wire electrodes to record the electromyographic activity. Data were quantified by normalizing all electromyographic activity during gait with electromyographic activity occurring during a sustained maximum isometric effort resisted either manually or with a dynamometer. The results indicated that the hip extensor muscles had different phasic patterns and moments of peak activity. During level walking, the semimembranosus and long head of the biceps femoris muscles displayed the greatest swing phase activity (beginning in mid-swing). The adductor magnus muscle followed with its onset in terminal swing. Both this muscle and the gluteus maximus were the principal hip extensors active during the loading response. For ascending stairs, the lower portion of the gluteus maximus muscle proved to be the main hip extensor during the loading response and mid-stance. The findings also showed that the upper portion of the gluteus maximus muscle functioned more like the gluteus medius muscle than the lower portion of the gluteus maximus muscle during both level and stair walking.

Adult↗
PubMed1983

Use of the Phoenix system for bacteriology.

A dedicated microbiology data processing system with remote batched job entry to an obsolete computer, has been superseded by the inclusion of bacteriology in an on-line interactive clinical pathology system which had previously incorporated chemical pathology and haematology. The original Phoenix system has been adapted to allow for the entry of bacteriology data using mnemonic codes and to deal with the problems caused by the longer processing time of bacteriology specimens. Particular advantages of the new system include the immediate linkage of all specimens for each patient and an easy recall and display of results in the laboratories and on the wards.

Bacteriology↗
PubMed1983

Chronic cobalamin inactivation impairs folate polyglutamate synthesis in the rat.

Nitrous oxide, by inactivating cobalamin in vivo, produces a suitable animal model for cobalamin 'deficiency.' The synthesis of folate polyglutamate with tetrahydrofolate as substrate is severely impaired in the N2O-treated rat, but is normal with formyltetrahydrofolate as substrate. Methionine restores the capacity of the N2O-treated rat to utilize tetrahydrofolate the minimum effective dose being 16 mumol. S-Adenosylmethionine was somewhat less effective than methionine but 5'methylthioadenosine, a product of S-adenosylmethionine metabolism, was significantly more effective than methionine in correcting the defect in folate polyglutamate synthesis. 5'Methylthioadenosine is metabolised to yield formate. It is suggested that these compounds have their effect in correcting folate polyglutamate synthesis by supplying formate for the formylation of tetrahydrofolate. Formyltetrahydrofolate, at least in the cobalamin-inactivated animal, is the required substrate for folate polyglutamate synthesis. Cobalamin is concerned with the maintenance of normal levels of methionine and this in turn is a major source of formate through S-adenosylmethionine and 5'methylthioadenosine.

Adenosine↗
PubMed1983

Rehabilitation of the neurologically disabled patient: principles, practice, and scientific basis.

Rehabilitation is a therapeutic program specifically directed toward restoring the optimum level of function available to patients with severe permanent disabilities. It complements standard care, which focuses on curing the primary pathology. Preventive rehabilitation is designed to minimize the complications of inactivity that tend to develop during a protracted curative process (contractures, pressure sores, muscle atrophy, cardiopulmonary deconditioning, cognitive dulling). Comprehensive rehabilitation focuses on the restoration of function. It encompasses physical reconditioning, teaching new ways to accomplish the basic tasks of locomotion, object handling, personal care, relationships with family and society, employment, and recreation. The rehabilitation program is largely designed and provided by a team of allied health professionals, each an expert in one area of function. Reverting to a less dominant role, the physician provides leadership by defining the stress (activity) tolerance of the patient's pathology, coordinates the team, and manages intercurrent problems that arise. Comprehensive rehabilitation is an in-hospital program. Less intense elements can be provided in a skilled nursing facility, out-patient clinic, or the patient's home. The details of the rehabilitation process vary with the nature of the patient's primary pathology. These have been illustrated in this review of the programs for two very diverse situations. Spinal cord injury introduces varying levels of physical incapacitation. Conversely, brain injury primarily creates a cognitive and behavioral deficit. Both are complex problems requiring comprehensive rehabilitation if the impairment is severe.

Brain Injuries↗
PubMed1983

Lower extremity electromyographic analysis of running gait.

Onset of firing for the quadriceps, hamstrings, and gastroc soleus groups during running, both on a treadmill and over ground, was determined in seven normal adult male subjects. Surface and wire electrode data were collected simultaneously from 959 individual gait cycles. The mean velocity over ground was 274 +/- 38 m/minute, with a mean cadence of 171 +/- 14 steps/minute. The treadmill was set at 107 m/minute (4 miles/hour), and the subjects' mean cadence was 147 +/- 11 steps/minute. Over ground, the mean swing/stance ratio was 70/30 +/- 3%, and that for the treadmill was 60/40 +/- 6%. Like muscle groups on the right and left showed a mean difference in onset of muscle activity of 1.3% (+/- 4.6%) when measured during a minimum of ten cycles per subject for each test condition. The average difference in time of onset between the surface and wire electrodes was 2% (SD +/- 4.9%) on the treadmill and 1.5% (SD +/- 3.7%) for over-ground running. These differences are not statistically significant. Surface and wire electrode data have been determined to be equivalent only for regional synergistic muscle groups and should not be extrapolated to compare functions of individual muscles within those groups.

Adult↗
PubMed1983

Adduction contracture of the thumb in cerebral palsy. A preoperative electromyographic study.

In twenty-three patients with cerebral palsy and functional spastic hemiplegia, the contracted thenar-adductor space of the involved hand was evaluated by electromyography. The needle electromyogram was used to determine if the patient had selective control of the adductor muscle. In eight patients only partial myotomy of the adductor muscle during z-plasty of the web was performed because selective control of that muscle was present during either grasp or release. In four patients a complete release was done, and in two of them the ability to pinch was impaired.

Adolescent↗
PubMed1982

Stereotactic surgery using the "therapeutic" CT scanner.

Computerized tomography (CT) has become the natural imaging partner during stereotactic brain operations. At last a radiographic technique has been developed that actually visualizes the target and surrounding brain. Used intraoperatively, CT confirms accurate position of the probe, monitors biopsy or lesion techniques, immediately assesses results, and reduces the risks of operative complications. When appropriate markers are provided in the CT image, the CT computer rapidly generates target coordinates by converting CT coordinates to stereotactic frame coordinates. The same CT computer can be used to preselect the best trajectory and preplot the probe's path before insertion, using each patient's own "CT brain map." An accuracy of 1 mm has been achieved. The range and purpose of using an integrated CT-stereotactic system in the assessment of 11 patients with deep brain lesions is described. Operations are performed with the patient placed in the CT scanner. The stereotactic frame, constructed with low-atomic-number materials, permits nearly artifact-free CT images. With this stereotactic approach, CT has become part of the surgical armamentarium. Stereotactic surgery will soon be performed in an operating room equipped with such a "therapeutic" scanner.

Adolescent↗
PubMed1982

A comparison of tetrahydrofolate and 5-formyltetrahydrofolate in correcting the impairment of thymidine synthesis in pernicious anaemia.

5-formyltetrahydrofolate and tetrahydrofolate were added to marrow cells from patients with untreated pernicious anaemia at 1, 5 and 50 nmol doses in the deoxyuridine suppression test. At all 3 dose levels formyltetrahydrofolate was significantly more effective in correcting the defect of thymidine synthesis in pernicious anaemia, than tetrahydrofolate. The data suggest that formylation of tetrahydrofolate is necessary for its normal utilization.

Anemia, Pernicious↗