Effects of xylazine and acepromazine on bronchomotor tone of anaesthetised ponies

The effects of xylazine (an alpha 2-adrenoceptor agonist) and acepromazine (an alpha-adrenoceptor antagonist) on bronchomotor tone were investigated in seven anaesthetised, apnoeic ponies using a computer aided forced oscillation technique, which separates changes in bronchial calibre from changes in lung volume. Both agents produced bronchodilatation and a decrease in lung volume.

Effect of surgical stimulation on the auditory evoked response

Previous studies have shown a dose-related effect of a number of general anaesthetic agents on the early cortical waves in the auditory evoked response (AER). In this study the effect of surgical stimulation on these waves was examined in 11 patients anaesthetized with thiopentone, nitrous oxide and halothane and paralysed with pancuronium. The inspired nitrous oxide concentration and end-tidal halothane concentration were held constant at 70% and 0.3%, respectively, and baseline AER recordings were made. Following surgical stimulation there was a progressive and significant increase in the amplitude of waves Nb and Pb/Pc. Unambiguous autonomic responses were seen in three patients, but these were not significantly correlated with changes in the AER. We conclude from this, and previous studies, that the amplitude of cortical waves in the AER are sensitive not only to anaesthetic concentration but also to surgical stimulation. The AER may, therefore, provide a useful index of depth of anaesthesia, that is the balance between the effects of surgical stimulation and anaesthetic depression on central nervous system activity.

Nondetectable levels of interferon gamma is a critical host defense during the first day of herpes simplex virus infection

Previous studies have demonstrated the importance of IFN alpha/beta in resistance to primary viral infections. However, the role of IFN gamma in primary infections is unclear. The present studies were undertaken to determine whether IFN gamma induction was an important early host defense against primary HSV infection. The approach was to block the IFN gamma response with antibodies to IFN gamma prior to infection and at various times post-infection (p.i.). The data indicates that treatment of mice with anti-IFN gamma prior to infection enhanced mortality (89% vs 37%). Anti-IFNs given at various times post HSV challenge proved most effective within the first 24 h of infection. The above results suggest for the first time that IFN gamma mediates important host defense(s) early during primary HSV infection. Similar results were obtained using antibody to IFN alpha/beta.

Effect of halothane, enflurane and isoflurane on bronchomotor tone in anaesthetized ponies

The effects of halothane, enflurane and isoflurane on bronchial calibre were investigated in five anaesthetized ponies using a computer-aided forced airflow oscillation technique to derive specific lower airways conductance (s.Glaw) and expiratory reserve volume (ERV). All the agents tended to increase s.Glaw (indicating bronchodilatation), but ERV was reduced by halothane and enflurane, and increased by isoflurane. It was concluded that the effects of these agents on bronchomotor tone were similar to those which occur in man. However, the reasons for the differences in their effects on ERV compared with those found in man remain to be determined.

Prophylactic effect of aminophylline and salbutamol on histamine-induced bronchoconstriction

The effect of salbutamol 200 micrograms aerosol, i.v. high-dose aminophylline 670 mg or placebo (aerosol and infusion) on bronchomotor tone were compared in normal volunteers before and after bronchial provocation with histamine aerosol 500 micrograms. The study was a double-blind cross-over design. Specific airways conductance of the lower airway (s. Glaw) was measured using a forced airflow oscillation technique. All subjects receiving aminophylline had tremor and irritability, whereas after salbutamol there were no noticeable systemic or psychological effects. Before the administration of histamine, salbutamol caused significant bronchodilatation compared with control: aminophylline did not induce a significant change in airway conductance. The effect of histamine administration on s. Glaw was only partially blocked by the high dose of aminophylline, but was completely blocked by salbutamol.

Prospective study of perinatal transmission of Chlamydia trachomatis

During a five-year period, 262 (4.7%) of 5,531 pregnant women had positive cervical cultures for Chlamydia trachomatis, and 131 of their infants were followed up prospectively to ascertain the outcome of chlamydial exposure during the birth process. Culture-confirmed inclusion conjunctivitis of the newborn was seen in 23 (18%) of the infants. Chlamydial pneumonia was diagnosed in 21 (16%) of the infants at risk. Chlamydia trachomatis was recovered from 47 of the infants (36%), while 79 (60%) showed serologic evidence of infection. Subclinical rectal and vaginal infections were detected in 14% of infants at risk. In our population, 2.8% of newborn infants show serologic evidence of perinatal chlamydial infection and 1.4% develop either chlamydial pneumonia or conjunctivitis. Incidence rates of this magnitude indicate the need for programs aimed at preventing perinatal transmission of C trachomatis.

Effect of isoflurane on bronchomotor tone in man

Twenty patients were anaesthetized with thiopentone, the trachea intubated and the lungs ventilated with 70% nitrous oxide and oxygen. Normocapnia was maintained and, following control measurements of the specific conductance of the lower airways (s.Glaw), either 1.7% isoflurane or 1.3% halothane was added to the inspired gas mixture, 10 patients receiving each drug. s.Glaw was measured repeatedly during the next 30 min. There was a tendency for s.Glaw to increase--indicating a reduction in bronchomotor tone--during the administration of isoflurane, the effect approaching statistical significance. The administration of halothane was associated with a significant increase in s.Glaw. There was a statistically significant increase in the expiratory reserve volume, and a decrease in mean respiratory resistance over the tidal range in both groups. These results indicate that isoflurane does not cause an increase in bronchomotor tone, and may have a tendency to decrease it. This suggests that the previously reported increase of respiratory resistance during isoflurane anaesthesia resulted from a reduction in lung volume, rather than a change in bronchomotor tone.

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.

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.

Pronounced, episodic oxygen desaturation in the postoperative period: its association with ventilatory pattern and analgesic regimen

The respiratory effects of two postoperative analgesic regimens were compared in two groups of 16 patients each, recovering from general anesthesia and major surgery. One group received a pain-relieving dose of iv morphine (mean, 18.1 mg), with the same dose repeated as a continuous intravenous infusion over the subsequent 24 h. The other group received regional anesthesia using bupivacaine. The patients were monitored for 16 h after surgery. The two analgesic regimens provided patients with comparable analgesia throughout the study period, but there were quite different respiratory effects in the two groups. Ten patients receiving morphine infusions had a total of 456 episodes of pronounced oxygen desaturation (SaO2 less than 80%). These occurred only while the patients were asleep, and all were associated with disturbances in ventilatory pattern, namely, obstructive apnea (144 episodes in eight patients), paradoxic breathing (275 episodes in six patients), and period of slow ventilatory rate (37 episodes in one patient). In contrast, in patients receiving regional anesthesia, oxygen saturation never decreased below 87%. Central apnea, obstructive apnea, and paradoxic breathing occurred more frequently in patients in the morphine group (12, 10, and 10 patients, respectively) than patients in the regional anesthesia group (4, 3, and 5 patients, respectively). The interaction of sleep and morphine analgesia produced disturbances in ventilatory pattern, causing profound oxygen destruction. These results suggest that postoperative pain relief using regional anaesthesia has a greater margin of safety in terms of respiratory side effects than does the continuous administration of opiates.

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.

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.

Factors affecting balance and ambulation following stroke

Ninety consecutive patients with hemiplegic involvement following a single cerebrovascular accident were studied to assess the relative importance of factors affecting balance and ambulation. Only 50% of the patients achieved a community level of ambulation. Intact balance reactions correlated strongly with the ability to walk (r = 0.79). Balance was found to be dependent on limb control and proprioception. Age, sex, hemiplegic side, and structural factors did not correlate with function or recovery. The total score in each category of function was more highly correlated with balance and ambulation than were the individual scores.

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.

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.

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.

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.

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.

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.