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Biomedical subjects

C Jordan

Publications and source records attributed to C Jordan.

At least 73 records · Page 4Linked to original sources
PubMed1985

Episodic postoperative oxygen desaturation: the value of added oxygen.

Six patients were studied following general anaesthesia for cholecystectomy or hip replacement. Intravenous morphine was given for postoperative pain relief. Continuous measurements were made of breathing pattern and arterial oxygen saturation for a 12-hour period postoperatively. The effect of breathing either air or 28% oxygen for alternate 2-hour periods was examined. There was no significant effect of oxygen on the number of periods of central apnoea, obstructive apnoea or partial upper airways obstruction. The number of episodes of decreases in oxygen saturation to below 80%, associated with these breathing disturbances, was reduced from 59 to zero by the administration of oxygen. There was a gradual improvement in oxygenation whilst breathing air during the 12-hour postoperative period. The administration of oxygen had a beneficial effect on average arterial oxygen saturation.

Airway Obstruction↗
PubMed1985

Histochemical and morphometric changes in muscles of stroke patients.

There is little information on the muscle fiber changes or the fiber type affected in supraspinal hemiplegia. Muscle biopsy specimens from 20 patients with stroke, obtained during orthopedic reconstruction, were examined by modern histochemistry. Atrophy was present in all of the muscles, affecting Type 1 fibers in 100% and Type 2 fibers in 95% of the patients. Type 2 atrophy was more severe than Type 1 atrophy. Group atrophy and fiber type grouping, present in 40%, seemed related to peripheral nerve or root damage. Hypertrophy of Type 1 fibers was present in 45%, associated with Type 2 hypertrophy in 15%. Although diffuse morphometric atrophic seemed not to correlate with the level of motor activity in this group of 20 patients, hypertrophy appeared related to activity. Hence, efforts to mobilize and rehabilitate stroke patients cannot prevent atrophy of some fibers, they seem to stimulate a hypertrophy not seen in inactive patients.

Adult↗
PubMed1984

Measurement of systolic time intervals during exercise using inductive plethysmography.

Measurement of systolic time intervals (STI) provides a noninvasive assessment of cardiac function in resting subjects. However, large motion artifacts often limit their application during exercise. To improve such measurements, we employed a new lightweight carotid arterial pulse transducer and minimized the artifacts by computerized signal averaging. The carotid pulse was recorded with an inductive plethysmographic transducer band (CIP) wrapped around the neck. STI derived from these measurements were compared to standard measurements from a funnel-shaped cup attached to the neck and connected to a pressure transducer (CUP) in 12 normal subjects at rest and with graded bicycle ergometry. To compare the techniques, CIP and CUP signals, together with the EKG and phonocardiogram, were connected separately to two microcomputer systems. The systems were triggered from the EKG and averaged the signals over 16 or 32 heart beats. Semi-automatic analysis of the averaged signals provided estimates of left ventricular ejection time (LVET), pre-ejection period (PEP) and electromechanical systole (QS2). Motion artifact levels of the unprocessed signals were similar with both CIP and CUP methods but were greatly reduced by signal averaging. All LVET values using CIP fell within 10% of CUP values. 85% of PEP values using CIP were within 20% of CUP values. Increasing exercise loads produced appropriate decreases in QS2, LVET, PEP and PEP/LVET consistent with increased myocardial contractility. The CIP proved comfortable to wear and did not require critical positioning as did the CUP. Measurement of STI complements exercise pulmonary testing with useful information of cardiac function.

Adult↗
PubMed1984

Infections in the alcoholic.

Serious infections appear to occur more frequently in alcoholic patients. However, whether this is due to the effects of alcohol per se or to the other frequent complications of alcoholism--nutritional deficiencies, cirrhosis, and poor hygiene--has not been determined. The host factors that may underlie an increased frequency of infection in alcoholics and the clinical infectious syndromes associated with alcoholism are described.

Adult↗
PubMed1984

Evidence for altered vascular reactivity in sodium-sensitive young subjects with borderline hypertension.

To assess mechanisms associated with the pressor effects of a high sodium diet in susceptible individuals, the hemodynamic and hormonal effects of sodium depletion and repletion were studied in 33 normal subjects and 30 subjects with borderline hypertension. The hypertensive group had significantly higher mean arterial pressure, weight, hematocrit, and upright plasma renin activity. Forearm hemodynamics were measured during periods of ad lib diet, 10 mEq, and 200 mEq sodium diet. The fall in forearm resistance during reactive hyperemia was inversely related to mean arterial pressure at rest (R = .400, p less than .005) and rose significantly in hypertensive subjects during salt depletion, 39 +/- 3.6 to 61 +/- 6.1 mmHg/ml/min/100 g (p less than .05). Sodium sensitivity in either normotensive or borderline hypertensive subjects was defined as an increase in mean blood pressure of more than 5% when sodium repleted. The individuals who were sodium sensitive had a higher forearm vascular resistance during sodium depletion than those who were sodium resistant, 67 +/- 10.5 versus 45 +/- 4.1 mm/ml/min/100 g (p less than .03). We conclude that young individuals with borderline hypertension already have alterations in vascular reactivity. This trait is shared by normotensive individuals whose blood pressure rises in response to sodium.

Adult↗
PubMed1983

Effect of subanaesthetic concentrations of nitrous oxide on the regulation of ventilation in man.

The pattern of ventilation was studied in eight healthy male volunteers breathing, in sequence, air and then two subanaesthetic concentrations of nitrous oxide (20% and 40%). The effect of these gas mixtures on the response to an added inspiratory resistance (3.88 kPa litre-1s-1) was examined. During unrestricted breathing of 40% nitrous oxide, there was a significant decrease (P less than 0.05) in inspiratory time (TI), a concomitant increase in the rate of ventilation and a significant decrease (P less than 0.05) in the end-tidal carbon dioxide tension (PE'CO2) compared with air breathing. For the first breath on load while breathing 40% nitrous oxide, there were significant decreases (P less than 0.05) in the responses for TI and tidal volume (VT) compared with the responses when breathing air. TI, VT, minute volume and PE'CO2 were similar for each gas mixture during steady state breathing against resistance. The increase in PE'CO2 when breathing 40% nitrous oxide against the resistance represented a significant (P less than 0.01) difference in response to the load compared with that breathing air. There was no significant change in these variables when breathing 20% nitrous oxide.

Adult↗
PubMed1983

Enflurane anaesthesia causes graded changes in the brainstem and early cortical auditory evoked response in man.

The effect of increasing end-tidal enflurane concentration on the auditory evoked response was studied in six patients. After a standard induction, anesthesia was maintained with 70% nitrous oxide in oxygen and the end-tidal enflurane concentration was increased gradually from 0 to 1% over a period of 30 min. The averaged auditory evoked response was derived from the electroencephalogram and measurements were made of the latencies and amplitudes of waves I, III, V, Pa and Nb within the auditory evoked response. The latencies of all waves and the interpeak latencies I to V and III to V showed significant linear increases and the amplitudes of Pa and Nb showed significant linear decreases with increasing end-tidal enflurane concentration. These results could not be explained by changes in deep body temperature or end-tidal carbon dioxide concentration. The study demonstrated a dose-related direct effect of enflurane on the brainstem and early cortical components of the auditory evoked response.

Adolescent↗
PubMed1983

Effect of the antitussive glaucine on bronchomotor tone in man.

In view of the observation that the antitussive agent glaucine prevents histamine-induced bronchoconstriction in guinea pigs we investigated this agent for a possible peripheral action in man, using a new method for measuring changes in bronchomotor tone. The forced airflow oscillation method was used to determine respiratory resistance (Rrs) over a range of lung volumes (VL) in seven healthy supine subjects. Computer analysis of the hyperbolic relationship between Rrs and VL was used to determine the asymptotic resistance and yield estimates of lower airways conductance (Glaw). Specific lower airways conductance (sGlaw) was expressed as the slope of the linear plot of Glaw against VL and is a sensitive index of bronchomotor tone. After baseline measurements of sGlaw subjects received placebo or 60 mg glaucine orally according to a double-blind crossover protocol. Histamine, 500 micrograms, was inhaled 45 minutes later. Measurements of sGlaw were repeated every 10 minutes for two hours. Although there was a trend towards bronchodilatation after glaucine administration (sGlaw = 130% of baseline) there was no significant difference from the effect of placebo (sGlaw = 89% of baseline). After inhalation of histamine sGlaw fell to 26% of baseline after both glaucine and placebo (p less than 0.01). In a further study three subjects received glaucine and placebo according to an identical protocol except that the histamine was omitted. Again the increase in sGlaw failed to achieve significance. Glaucine does not affect the bronchoconstrictor response to histamine in man and there is no convincing evidence of an effect on resting bronchomotor tone.

Adult↗
PubMed1983

Ocular herpes simplex virus infection is diminished by depletion of B lymphocytes.

Rabbit anti-mouse mu-chain serum was used to deplete specifically IgM-bearing B cells and B cell function in BALB/c mice. B cell-depleted and normal littermates were infected via the cornea with herpes simplex virus type 1 (HSV-1) at 4 to 5 wk of age. B cell-depleted mice had a reduced number of lymphocytes bearing surface immunoglobulin and a greatly reduced ability to produce antibody. Mortality was reduced from 89% in normal controls to 42% in B cell-depleted mice (p less than 0.001) and peak virus shedding from eyes was also reduced as much as 90% in the B cell-depleted mice (p less than or equal to 0.0005). These results support the hypothesis that a B cell function of normal mice somehow contributes directly or indirectly to the enhanced mortality of mice infected with HSV.

Animals↗
PubMed1982

Electromyographic gait analysis before and after operative treatment for hemiplegic equinus and equinovarus deformity.

Gait electromyograms were obtained before and after tendon transfer, lengthening, or release in twenty-seven hemiplegic patients with equinus or equinovarus deformities. Abnormal patterns of muscle activity almost always were present preoperatively in the gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, flexor digitorum longus, peroneus brevis, and tibialis anterior muscles in these patients. The surgical procedures to correct the foot deformities altered the gross patterns of activity of most of the muscles operated on by very little. Of particular importance to the surgeon was the finding that the pattern of activity of the muscles whose tendon was transferred, lengthened, or released was not altered after operation. This finding makes the preoperative gait electromyogram a useful means of determining the appropriate surgical plan, since it is an indication of the type of muscle activity to expect postoperatively.

Adult↗
PubMed1981

Rapid improvement in abnormal pulmonary epithelial permeability after stopping cigarettes.

A new, non-invasive method of measuring pulmonary epithelial damage in man was compared with traditional tests of small-airway function. Pulmonary epithelial permeability was expressed as the half-time clearance from the lung into blood of (99m)Tc-diethylene triaminepenta-acetic acid ((99m)Tc-DTPA) deposited predominantly in the alveoli from an inhaled aerosol.Recovery from abnormal pulmonary permeability was recorded after stopping smoking for 21 days in a group of young symptomless cigarette smokers. Before stopping smoking there was a significant correlation between half-time lung clearance of (99m)Tc-DTPA and carboxyhaemoglobin concentration (r=0.69; p <0.05). There was no correlation between carboxyhaemoglobin value and closing volume, the only other abnormal test of airway function. Twenty-four hours after stopping smoking the mean half-time lung clearance of (99m)Tc-DTPA had increased significantly (p <0.001) from a baseline of 15.8 min (SEM 1.3 min) to 25.5 min (SEM 2.5 min). The mean half-time clearance continued to increase to a maximum of 35.5 min (SEM 3.1 min) at seven days, but was significantly less than the reported half-time clearance for non-smokers (59 min, SEM

Adolescent↗
PubMed1981

Alcohol induced discoordination is not reversed by naloxone.

It has previously been reported that prior administration of naloxone may prevent the decrement in performance produced by alcohol. To be clinical value, however, naloxone must be shown to reverse rather than prevent this decrement. This study examined the effect of naloxone given after consumption of alcohol. A double blind balanced crossover protocol was used to examine the effect of either 1.2 mg or 10 mg naloxone on the sensory-motor impairment produced by blood alcohol concentrations maintained between 75 and 85 mg/100 ml. This alcohol concentration significantly impaired two measures of sensory-motor performance, but there was no evidence that either dose of naloxone could reverse this decrement. We tested our subjects for a chlorpropamide alcohol flush but none gave a positive response. These results indicate that naloxone (1.2 mg or 10 mg) does not reverse the sensory-motor impairment produced by alcohol intoxication in subjects who do not exhibit a chlorpropamide alcohol flush. Nearly all the subjects exhibited somnolence after receiving alcohol and naloxone (1.2 mg or 10 mg) but not after receiving alcohol and saline.

Adult↗