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Biomedical subjects

R Johnston

Publications and source records attributed to R Johnston.

At least 109 records · Page 6Linked to original sources
PubMed1979

The 24-hour dexamethasone suppression test in a clinical setting: relationship to diagnosis, symptoms, and response to treatment.

Of 54 male psychiatric patients undergoing dexamethasone suppression tests in a clinical setting, 40% of those with a major depressive disorder showed escape from suppression over the 24 hours after dexamethasone administration, while all of the patients with schizophrenia, neurosis, alcoholism,and drug abuse showed normal pituitary-adrenal suppression. Only 10% of the depressed patients showed resistance to suppression 8 hours after dexamethasone administration. There was no difference between depressed patients who did and did not show escape from suppression in type of previous episodes, family history, symptoms, or medication. However, those who showed escape tended to respond better to treatment and to be rated as having a more severe depression. The theoretical and clinical implications of these findings are not yet clear.

Adult↗
PubMed1978

Occurrence and fate of organic and inorganic contaminants in marine animals.

Most chemical contaminants occur in highest concentrations in coastal waters, often maximized in very localized areas. In general, this situation represents the exposure pattern for marine animals. However, the availability of contaminant to an organism depends not only on its concentration but also on its chemical nature, its physical state, and whether the source of exposure is the surrounding seawater or the diet. Depending on the type of exposure, uptake occurs across absorptive surfaces, such as those of the respiratory apparatus or gastrointestinal tract, where selectivity may occur, even among neighboring homologs. Deposition in tissues, accumulation, degradation, or depuration depends on tissue type, metabolic processes, detoxification mechanisms, and the adaptive status of a particular animal. This hypothesis is examined briefly for hydrocarbons, pesticides, other miscellaneous organic contaminants, heavy metals, and radionuclides. It is concluded that most data relate to occurrence and distribution. Considerably less information is available on the underlying biochemical processes.

Animals↗
PubMed1978

Depressive syndrome in schizophrenia.

A depressive syndrome, closely resembling melancholia, was found in a large proportion of chronic schizophrenic men. Depression was most prominent during acute psychotic phases and was characterized by a delusional core of worthlessness and guilt. The depressive syndrome may persist throughout the patient's psychotic life and appears to be an integral component of schizophrenic psychopathology.

Adult↗
PubMed1977

F1-ATPase-catalyzed synthesis of ATP from oleoylphosphate and ADP.

Purified preparations of F1-ATPase (ATP phosphohydrolase; EC 3.6.1.3) isolated from yeast mitochondria catalyze the reaction of oleoylphosphate with ADP to yield ATP and oleic acid. Formation of ATP is specifically inhibited by the F1-ATPase inhibitor 1799 and by dinitrophenol. In the presence of F1, dinitrophenol "uncouples" the synthase reaction by causing rapid hydrolysis of oleoylphosphate without ATP formation. It is proposed that this F1 catalyzed ATP synthesis reaction corresponds to the terminal chemical step in oxidative phosphorylation.

Adenosine Diphosphate↗
PubMed1977

Homicidal aggression in schizophrenic men.

In a sample of 205 hospitalized schizophrenics, 59 men were found who made verbal threats to kill or physical attacks some time during their illness. All homicidal aggression occurred during active phases of psychosis, typically in a setting of acute excitement and in recurrent illnesses. Paranoid diagnoses were overrepresented. Closely related females were the prime targets, suggesting a resentment of dependence on a woman. An impersonal, compulsive urge appears to be the motivating force leading to physical attacks.

Aggression↗
PubMed1977

Preoccupation with death in schizophrenic men.

A systemic review of psychiatric histories of 205 hospitalized, schizophrenic men (veterans) revealed that 80 had expressed fear of dying, being killed, of no longer existing, or other evidence of preoccupation with death. These expressions of fear appeared either at the clinical onset of the psychosis, or during exacerbations, and often coincided with schizophrenic panic. The similarity of expressions of the fear among the patients was striking, and they were practically indentical from one exacerbation to the next. This consistency suggests that the fear of death stems from schizophrenic psychopathology rather than from individual situational influence. The explicitly stated preoccupation with death was quite common in this sample (40%), and contrary to expectation, was not limited to cases with favorable outcome.

Acute Disease↗
PubMed1976

Myofeedback: a new method of teaching breathing exercises in emphysematous patients.

The diaphragm of the emphysematous patient is low and limited in its excursions, producing an increased functional residual capacity and decreased pulmonary ventilation. This report describes our experiences with a new technique for 1) the training of abdominal-diaphragmatic (A-D) breathing and 2) the relaxation of accessory respiratory muscles in emphysematous patients. Abdominal muscle contraction during expiration has been shown to increase diaphragmatic excursions and, hence, pulmonary ventilation. Use of this technique has been limited, however, because of the difficulty in learning this breathing pattern. Through continuous audio and visual feedback of myoelectric potentials (myofeedback) from abdominal muscles, 12 patients learned A-D breathing. The lower rectus abdominis muscle was found to be the most suitable muscle for obtaining the myoelectric potentials. Similarly, by providing the patients with myofeedback from their accessory muscles, they decreased the use of these muscles, thus increasing their respiratory efficiency. With myofeedback, patients appear to learn new breathing patterns effectively and in fewer sessions than with conventional procedures.

Abdominal Muscles↗
PubMed1976

A survey of patients leaving a mental hospital against medical advice.

A consecutive series of 100 male psychiatric patients who requested release against medical advice during an 11-month period was compared with a control group consisting of a random sample of 100 patients admitted during the same period who did not submit such a request. The majority of those who submitted the request were alcoholics or schizophrenics. The authors found that a sizable number were either separated or divorced, were younger than patients in the control group, and were in more turbulent phases of their illness. A surprising finding was that 60 patients submitted the request while on an open ward.

Age Factors↗
PubMed1976

Electrically induced flexion reflex in gait training of hemiplegic patients: induction of the reflex.

Since the introduction of the concept of functional electrical stimulation, the use of multiple stimulation sites to activate several paretic muscles in a coordinated fashion during ambulation has been suggested. Rather than stimulating multiple muscles, we have applied a train of electrical pulses to a single skin area to activate several muscles simultaneously through the induction of a flexion reflex, and evaluated the effectiveness of this reflex in producing or assisting the swing phase of the gait cycle in the hemiplegic patient. Two considerations in selecting the best stimulus site were (1) the magnitude of the reflex as measured by the length of time the foot was off the floor following a stimulus and (2) the patient's tolerance to the stimulus. The magnitude of the reflex was proportional to the strength of the stimulus current in all skin areas tested; namely the sole, dorsum of the foot, and lower posterior thigh. Of the six patients tested a flexion reflex was not elicitable by sole stimulation in one and by posterior thigh stimulation in another. In every case, compared to the two other areas, stimulation of the sole was best tolerated and produced responses of equal or greater magnitude with the same intensity of current, even though larger voltages were required owing to greater tissue impedances. With a fixed frequency of 30 Hz, a pulse duration of 3 msec, and a stimulus current sufficient to produce the reflex, the duration of the reflex could be adjusted for each patient by varying the train duration from 100 to 700 msec. This technique offers a means of providing or assisting the swing phase in the gait training of the hemiplegic patient.

Aged↗
PubMed1976

Myofeedback for muscle retraining in hemiplegic patients.

The use of audiovisual displays of myoelectric potentials (myofeedback) has been suggested for retraining and strengthening of paretic muscles in patients with hemiplegia from stroke. This controlled study examines the specificity and efficiency of myofeedback in the strengthening of paretic muscles in hemiplegic patients. Eighteen patients with trace to fair-minus grade of deltoid muscle power resulting from strokes that had occurred at least six weeks earlier were randomly assigned to the six possible orders of accurate (true), positive noncontingent (placebo) and no feedback conditions. On three successive days, each patient received one session of each feedback condition, consisting of 20 isometric contractions of five seconds each with ten seconds of intervening rests. In addition, each patient's motivational level was rated. Averaged myoelectric potentials were quantified for each contraction for analysis. When the data were analyzed without grouping, no statistical differences among the three feedback conditions were noted. However, when the subjects were grouped according to age and motivational level, during true and no feedback sessions, the older and the poorly motivated groups were found to show progressive increment of myoelectric output, whereas the younger and the better motivated showed the opposite results. With placebo feedback, both groups showed progressive decrement of myoelectric output. It is concluded that the effect of myofeedback is nonspecific at least in its short-term application for the retraining of hemiplegically paretic muscles.

Adult↗