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Biomedical subjects

D R Jones

Publications and source records attributed to D R Jones.

At least 325 records · Page 18Linked to original sources
PubMed1981

On the stability of Innovar, a neuroleptic analgesic, for cardiovascular experiments.

The effects of 0.2 and 0.5 mL/kg Innovar (a neuroleptic analgesic) on cardiovascular functions and reflexes in rabbits were measured. We recorded the effects of Innovar on arterial pressure, heart rate, respiration rate, ventricular contractility, arterial oxygen tension, as well as the drug's effects on the bradycardia and vasoconstrictor response to cigarette smoke stimulation of the nose (the so-called "nasopharyngeal reflex"). In animals given 0.2 mL/kg Innovar, all steady state cardiovascular variables had returned to pre-Innovar levels in 45 min, as had the efficacy of the nasopharyngeal reflex. In animals given 0.5 mL/kg Innovar, all steady state cardiovascular variables, except PaO2, were slightly but significantly depressed for up to 135 min after injection. The nasopharyngeal reflex returned to normal within 90 min. Because of the calmative and analgesic effects of Innovar, and its only moderate effects on cardiovascular functions and reflexes, we feel it is a suitable analgesic agent for cardiovascular experiments where neither fully conscious nor surgically anesthetized animals can be used.

Analgesics↗
PubMed1981

On chemoreceptor control of ventilatory responses to CO2 in unanesthetized ducks.

Using cross perfusion between pairs of animals we examined the effects of increases in arterial CO2 tension (Paco2) at pulmonary, carotid body, and central chemoreceptors on ventilation in unanesthetized, spontaneously breathing White Pekin ducks. By adjusting the level of inspired CO2 of either the experimental or donor animals it was possible to manipulate Paco2 at any one or combination of the receptor groups. Stimulation of central chemosensitive areas alone was three to four times more effective in increasing both frequency and minute ventilation (Ve) than stimulation of the carotid bodies alone. Increases in tidal volume were small in both instances. Increasing PCO2 in the pulmonary circulation of an innervated lung, independent of changes in Paco2 at the carotid body or head, had no effect on VE. We conclude that central chemoreceptors play the major role in a steady-state response of awake ducks to CO2 while the carotid bodies play a smaller but still significant role. The intrapulmonary chemoreceptors play no role in the response per se although their inhibition by high airway CO2 causes marked effects on the pattern of breathing

Animals↗
PubMed1981

Biofeedback rehabilitation of airsick aircrew.

The biofeedback treatment of 20 aircrew, disabled by chronic severe airsickness, is reported. The USAF School of Aerospace Medicine (SAM) Airsick Rehabilitation Program requires careful selection to insure high motivation and thorough medical screening to rule out intercurrent medically disqualifying conditions. Patients are trained in relaxation techniques and placed in a modified Barany chair, capable of tilting as well as rotating. Psychological responses to motion stimulation are constantly monitored by both patient and investigators. Motion sickness is provoked, which the patient learns to control and abort through exercising autonomic control. Of 19 eligible, 16 have been returned to fully flying duties.

Aerospace Medicine↗
PubMed1981

Determination of clovoxamine concentration in human plasma by electron capture gas chromatography.

The antidepressant drug clovoxamine can be specifically and sensitively quantitated in human plasma by electron capture gas chromatography. Clovoxamine and the internal standard fluvoxamine are extracted into ethyl acetate from plasma at pH 12, back-extracted into phosphoric acid, and hydrolyzed at 90 degrees C to form ketone derivatives, which are then re-extracted into hexane for injection into the chromatograph. As little as 1 microgram of clovoxamine per liter of plasma can be measured. The coefficients of variation (CV) for th analysis at concentrations of 10 and 100 micrograms/L are respectively: within-run, 5.4% and 2.7%; between-run, 17.5% and 7.0%. When this assay was applied to plasma from individuals involved in an early clinical trial of clovoxamine, steady-state plasma concentrations ranged from 50 to 77 micrograms/L 3 h after a 50-mg oral dose of clovoxamine fumarate.

Antidepressive Agents↗
PubMed1981

The individual's vs. the organization's doctor: value conflict in psychiatric aeromedical evaluation.

Physicians who perform aeromedical evaluations are aware of the value conflicts inherent in being both a physician and a social agent. This paper examines some of the conflicts which occur when the psychiatrist acts as an aeromedical examiner. Five areas are examined: 1) the use by the psychiatrist of the authority delegated by the social system, 2) issues of confidentiality, 3) efforts of the social system to influence the psychiatrist's findings, 4) the requirements to make decisions in areas where scientific data is lacking, and 5) the physician's imperative to "do no harm" to his patient. Recommendations to minimize the impact of these factors through recognition, open discussion, and thoughtful structuring of the physician-patient relationship are made.

Aerospace Medicine↗
PubMed1980

Cerebral energy metabolism in diving and non-diving birds during hypoxia and apnoeic asphyxia.

1. Cerebral energy metabolism during apnoeic asphyxia and steady-state hypoxia was compared in ducks and chickens; ducks tolerate apnoeic asphyxia 3-8 times longer than chickens. 2. Fluctuations in the reduced form of respiratory chain nicotinamide adenine dinucleotide (NADH) were monitored from the left cerebral hemisphere by a noninvasive fluorometric technique and used as an indicator of mitochondrial hypoxia. NADH fluorescence was expressed in aribtrary units (a.u.) where 100 a.u. was defined as the fluorescence change from normoxia to anoxia. Electroencephalogram (e.e.g.) and surface Po2 were recorded from the right hemisphere. 3. After 1 min of asphyxia NADH fluorescence increased by 37 a.u.+/-3.60 S.E. of mean (n=54) in paralysed chickens and 8 a.u.+/-1.41 (n=55) in aralysed ducks. After 2 min the fluorescence increased by only 15 a.u.+/-1.95 in ducks. 4. Both species showed an isoelectric e.e.g. when fluorescence increased by approximately 35 a.u., indicating that anaerobic ATP production in ducks did not maintain brain function (e.e.g.) for a greater accumulation of respiratory chain NADH. 5. At a given decrease in tissue Po2 ducks and chickens showed the same level of NADH increase, indicating that both species are equally dependent on tissue Po2 for the maintenance of redox state. 6. We conclude that biochemical adjustment which enhance anaerobic ATP production and/or prolong oxidative phosphorylation during progressive hypoxia are not responsible for increased cerebral tolerance to apnoeic asphyxia in the duck.

Anaerobiosis↗
PubMed1980

Cerebral energy metabolism in mallard ducks during apneic asphyxia: the role of oxygen conservation.

Cerebral energy metabolism during apneic asphyxia was studied in ducks. Fluctuations in the reduced form of respiratory chain nicotinamide adenine dinucleotide (NADH) were monitored from the left cerebral hemisphere and used as an indicator of mitochondrial hypoxia. Electroencephalogram (EEG) and surface PO2 were recorded from the right hemisphere. Forced dives of 4- to 7-min duration on restrained ducks were characterized by bradycardia and an accumulation of NADH, which increased throughout the diving period. NADH returned to the preasphyxic level when breathing was resumed. In later experiments, asphyxia was produced by stopping artificial ventilation in paralyzed ducks. Asphyxia produced by this means caused similar changes in the measured variables (heart rate, blood pressure, and NADH fluorescence) to those obtained in forced submergence of nonparalyzed ducks. The inhibition of cardiovascular adjustments by atropine caused NADH to increase faster and tissue PO2 to decrease faster during apneic asphyxia than in nonatropinized ducks. We conclude that the oxygen-conserving cardiovascular adjustments play a key role in the increased cerebral tolerance to apneic asphyxia in ducks.

Animals↗
PubMed1980

Intrarenal blood flow distribution in the genetically hypertensive rat.

Distribution of intrarenal blood flow has been measured in genetically hypertensive (GH) and normotensive (N) rats (aged 17--23 weeks) by a 133Xe washout technique without opening the abdominal cavity. Three different specific flow compartments were found in the rats. The distribution of the intrarenal blood flow to the fast compartment was reduced in the GH rats when compared with the N rats and the rate of flow in it was also reduced. The flow rate in the second compartment was the same in the two strains, the distribution to it being relatively greater in the GH rats. The mean renal blood flow index (in ml/min/g of kidney) was reduced in the GH rats. It is not at present clear whether these differences are due to the hypertension or represent a causative factor in the hypertension.

Animals↗
PubMed1980

The role of vagal afferent information and hypercapnia in control of the breathing pattern in chelonia.

The normal breathing pattern of the turtle, Chrysemys picta (Schneider), consists of periods of continuous breathing interspersed with periods of breath holding. During each ventilatory period respiratory frequency and tidal volume are controlled independently. There is a large variability in inspiratory and expiratory gas-flow rates yet tidal volumes are maintained within narrow limits by adjustments of the lengths of the active inspiratory and expiratory intervals. Lung volume information carried within the vagus nerve is responsible for the careful regulation of tidal volume as well as for modulation of the air flow rates and lowering of the threshold of the mechanism initiating expiration following breath holding. Increases in pulmonary minute ventilation during hypercapnia are caused by increases in respiratory frequency due solely to a shortening of the periods of breath holding. There is some increase in tidal volume but the breath length remains constant and thus the frequency of breathing within each ventilatory period also remains constant. After vagotomy, changes in minute ventilation due to hypercapnia stem primarily from changes in tidal volume while changes in respiratory frequency are greatly reduced.

Afferent Pathways↗
PubMed1980

Aeromedical transportation of psychiatric patients: Historical review and present management.

Early references to aeromedical transportation do not address the movement of psychiatric patients. They were specifically excluded from routine movement by air early in World War II, but their movement by returning troop ship had an unacceptable rate of mortality and morbidity. The tactical experience in this matter acquired by battlefield necessity led to the use of an aeromedical classification system indicating the need for restrains, sedation, and properly trained attendants. This time-tested system is used today in almost identical form. Most of these patients require only the good medical care and common courtesy that other patients require. A few may cause anxiety because of their attitudes or actions. Proper preflight planning includes giving patients accurate information, dealing with their situational anxieties, considering the aeromedical implications of psychotropic medications, anticipating disruptive behavior, and using interpersonal skills to lessen anxiety in flight.

Aerospace Medicine↗
PubMed1980

What the repatriated prisoners of war wrote about themselves.

Books written or contributed to by U.S. military men repatriated from Vietnamese prison camps were reviewed, with particular attention to common themes of effective coping strategies. The underlying theme was an internal standard of behavior which each set for himself. This took the specific forms of loyalty to country, to family, to fellow prisoners, or to a self-image. This letter involved considerable use of denial at times. Religious convictions were important to some, but not to all. There was no evidence of the "identification with the aggressor" phenomenon that has been reported in some other prisoner situations. Some men reported beneficial aspects of the captivity situation, usually phrased in terms of personal growth. Mature coping skills include healthy humor, sublimation, anticipation, and the maintenance of self-esteem through an awareness of service.

Adaptation, Psychological↗