Oxygen-independent killing by alveolar macrophages.

We have found that normal alveolar macrophages can kill an intracellular parasite by a mechanism that does not involve toxic metabolites of oxygen. We studied the interaction between Toxoplasma gondii and rat alveolar macrophages in vitro. We were interested in Toxoplasma because it causes pneumonia in immunosuppressed patients but not in healthy individuals, and we chose the rat because it resembles immunocompetent human subjects in being resistant to T. gondii. Resident rat alveolar macrophages could kill large numbers of T. gondii. This occurred without a respiratory burst as judged by intracellular reduction of nitroblue tetrazolium and quantitative release of superoxide. Furthermore, scavengers of toxic oxygen metabolites had no effect on the toxoplasmacidal activity of the alveolar macrophages, nor did prior exhaustion of their respiratory burst with PMA. Whereas acid pH (e.g., 4.5-6.0) rapidly kills extracellular T. gondii, raising of the intralysosomal acid pH of rat alveolar macrophages by incubating them with weak bases did not inhibit their ability to kill T. gondii. Killing of Toxoplasma occurred within 1 h of initial exposure to the alveolar macrophages. However, there was no evidence that killing preceded ingestion; Toxoplasma attached to the surface of the cell appeared viable, and when phagocytosis was blocked with sodium fluoride the organisms survived. These results indicate that rat alveolar macrophages possess a powerful nonoxidative microbicidal mechanism, which is distinct from acidification of the phagolysosome but which probably involves phagosome formation. This mechanism may be clinically relevant, for we have recently observed that human alveolar macrophages also kill T. gondii by an oxygen-independent process.

Breathing, sleep, and diabetic autonomic neuropathy.

Sudden, unexplained deaths are relatively common in diabetic autonomic neuropathy. As disturbed autonomic function has been associated with sleep apnea, and sleep apnea with sudden death, we recorded breathing patterns, arterial oxygen saturation, and EEG during sleep in 8 male diabetic subjects with severe autonomic neuropathy and 8 age-matched, male diabetic subjects without autonomic neuropathy. None of the patients with autonomic neuropathy had more than 11 apneic episodes per night, and there were no significant differences between the two groups in the number of sleep apneas, the duration of individual apneic episodes, the total duration of irregular breathing during sleep, or the duration and quality of sleep. The arterial oxygen saturation when awake and the lowest arterial oxygen saturation during sleep were also similar in both groups. Thus, diabetic patients with severe autonomic neuropathy have normal breathing patterns and oxygenation during sleep, and it is unlikely that sleep apnea causes these unexpected deaths.

Night sleep of patients with chronic ventilatory failure and age matched controls: number and duration of the EEG episodes of intervening wakefulness and drowsiness.

Characteristics of the episodes of wakefulness and drowsiness (stage 0 + 1) intervening in a night of electrophysiologically monitored sleep were compared in a homogeneous group of 13 patients (mean age 57 years) with severe hypoxic chronic bronchitis and emphysema (blue and bloated variety) and 8 age matched control subjects. The total amounts of stage 0 + 1 accumulated over one night (preceded by one night of adaptation) were high in both groups (28% in the patients, 22% in the control subjects). A significant difference was found in the number of brief arousals (episodes of stage 0 + 1 lasting for less than 1 min), which averaged 10/h of sleep in the patients, and 6/h of sleep in the control subjects (p less than 0.05, two tailed). The numbers of longer episodes of stage 0 + 1 were not significantly different and varied independently from the numbers of brief arousals in the individuals. Only a small proportion (8 %) of brief arousals was linked to episodes of hypopnea or apnea in the bronchitic patients. Large numbers of brief arousals/h of non rapid eye movement sleep inthe bronchitic patients correlated significantly with small percentages of stage 3 + 4 sleep (p less than 0.05), and were associated with smell numbers of hypoxemic episodes occurring predominantly in rapid eye movement sleep. The findings indicate a more fractionated sleep in the patients with chronic hypoxic bronchitis, and suggest that the brief arousals represent a limiting factor rather than a result of the nocturnal hypoxemic episodes occurring in these patients.

Home oximetry studies for diagnosis of sleep apnea/hypopnea syndrome: limitation of memory storage capabilities.

BACKGROUND: Memory oximeters enable diagnostic studies for sleep apnea hypopnea syndrome (SAHS) to be performed in the home. However, memory capabilities may be limited. STUDY OBJECTIVES: To compare a pulse oximeter used at home with an 8-h memory, storing data every 12 s, and in the laboratory, with on-line recording every 2 s. DESIGN: Prospective cohort study. SETTING: Patients' homes and a sleep laboratory. PATIENTS: One hundred patients with suspected SAHS. MEASUREMENTS: Home oximetry and a laboratory full polysomnography. The number of >/= 4% dips in pulse oximetric saturation (SpO(2)) was calculated for each study. Daytime sleepiness was assessed by the Epworth Sleepiness Scale (ESS) score. RESULTS: The mean dips per hour were 5.3/h (range, 0 to 53/h) for home studies and 13.4/h (range, 0 to 106/h) for laboratory studies; the relationship between home and laboratory studies was as follows: home = (0.4 x laboratory) - 0.01 +/- 11.2; r(2) = 0.64. Mean difference was 8.4/h (- 2.5 to + 77.9/h), which correlated with the mean of the measurements. At a cutoff point of 10/h, 52 studies were both negative and 13 studies were both positive. Nineteen home studies were false-negatives. Sensitivity was 0.41, and specificity was 1.0. In these 19 studies, 7 patients had an ESS score > 10 and 4 patients had an ESS score > 14. To confirm that differences were due to different sampling rates, 16 additional patients had on-line data and stored data collected simultaneously in the laboratory. Mean dips per hour were 3.2/h (range, 0.1 to 18.3/h) for the stored data and 8.34/h (0.2 to 22.8/h) for on-line data; the relationship being stored was as follows: 0.5 on-line - 1.17 +/- 2.6; r(2) = 0.69. Mean difference was 5.2/h (0.04 to 15.4 h), which correlated with the mean of the measurements. CONCLUSION: Home studies using a memory storage pulse oximeter may underestimate the number of hypoxic dips, probably due to sampling rates. Clinically significant hypoxic SAHS may therefore be missed.

Open lung biopsy in patients with non-Hodgkin's lymphoma and pulmonary infiltrates.

Patients with non-Hodgkin's lymphoma (NHL) are at increased risk for pulmonary infection with opportunistic pathogens associated with diminished cell mediated immunity. Open lung biopsy (OLB) frequently is recommended for diagnosis of pulmonary infiltrates in patients with NHL, but its usefulness for patient management and outcome has not been evaluated for patients with NHL. We reviewed the results of 20 consecutive OLB in 19 patients with previously diagnosed non-Hodgkin's lymphoma at Stanford University Medical Center during a nine-year period. Fifteen patients had known active lymphoma at time of OLB, and no patient had granulocytopenia. Ten of the 20 OLBs yielded specific diagnoses. A greater proportion of patients with stage I or II disease had specific diagnoses than patients with more advanced NHL. Five of 14 patients considered to have had a life threatening illness at the time of OLB had specific diagnoses from OLB vs five of six patients considered clinically stable. Chest roentgenograms that had discrete masses or nodules correlated with ability to establish a specific diagnosis by OLB. For patients in whom the results of OLB were nonspecific, management appeared unaffected by the OLB. The OLB in NHL appeared most useful for detecting recurrent NHL in clinically stable patients with discrete nodules or masses on chest roentgenogram. Pneumocystis pneumonia was the only infection identified by OLB.

Effect of bronchial challenge on breathing patterns and arterial oxygenation in stable asthma.

The effect of histamine or methacholine inhalational challenge on breathing patterns and oxygen saturation was investigated in ten stable asthmatic patients. We used the respiratory inductive plethysmograph to record respiratory timing and minute ventilation along with an ear oximeter to measure oxygen saturation (SaO2). As FEV1 fell during the challenge procedure, SaO2 also fell (average 3 percent). Furthermore, with histamine challenge, expiratory time (Te), inspiratory time (Ti), and breath period (Ttot) all increased; minute ventilation probably also fell. These changes in breathing pattern and SaO2 were reversed by inhalation of a beta 2-agonist. However, no such changes in breathing patterns were observed with methacholine challenge despite a similar fall in FEV1. Bronchial challenge produces hypoxia in stable asthmatic patients, which might result from a combination of hypoventilation with alteration in alveolar ventilation/perfusion relationships.

Sputum induction as an aid to diagnosis of active cytomegalovirus infection following bone marrow transplantation.

An 8-year-old boy received an allogeneic bone marrow transplant (BMT) for relapsed T cell acute lymphoblastic leukaemia. Because he was seropositive for cytomegalovirus (CMV), serial virological specimens were taken throughout the transplant period, and included those obtained by sputum induction. Sixty-one days following BMT he became unwell, and was found to have mild tachypnoea and reduced oxygen saturations. All investigations were negative, apart from that obtained by sputum induction, which was positive for CMV. He received appropriate therapy with good response. We conclude that the technique of sputum induction can be applied to aid diagnosis of active CMV infection following BMT.

Mechanism of transient nocturnal hypoxemia in hypoxic chronic bronchitis and emphysema.

In five patients with hypoxic chronic bronchitis and emphysema we measured ear O2 saturation (SaO2), chest movement, oronasal airflow, arterial and mixed venous gas tensions, and cardiac output during nine hypoxemic episodes (HE; SaO2 falls greater than 10%) in rapid-eye-movement (REM) sleep and during preceding periods of stable oxygenation in non-REM sleep. All nine HE occurred with recurrent short episodes of reduced chest movement, none with sleep apnea. The arterial PO2 (PaO2) fell by 6.0 +/- 1.9 (SD) Torr during the HE (P less than 0.01), but mean arterial PCO2 (PaCO2) rose by only 1.4 +/- 2.4 Torr (P greater than 0.4). The arteriovenous O2 content difference fell by 0.64 +/- 0.43 ml/100 ml of blood during the HE (P less than 0.05), but there was no significant change in cardiac output. Changes observed in PaO2 and PaCO2 during HE were similar to those in four normal subjects during 90 s of voluntary hypoventilation, when PaO2 fell by 12.3 +/- 5.6 Torr (P less than 0.05), but mean PaCO2 rose by only 2.8 +/- 2.1 Torr (P greater than 0.4). We suggest that the transient hypoxemia which occurs during REM sleep in patients with chronic bronchitis and emphysema could be explained by hypoventilation during REM sleep but that the importance of changes in distribution of ventilation-perfusion ratios cannot be assessed by presently available techniques.

An assessment of sputum induction as an aid to diagnosis of respiratory infections in the immunocompromised child.

Sputum induction using nebulised hypertonic saline was performed in two groups of immunocompromised children, one group with symptoms of respiratory infection and one group without. The asymptomatic group were bone marrow transplant (BMT) recipients, all seropositive for cytomegalovirus infection (CMV). Organisms were identified in three of 14 induced sputum specimens obtained from the symptomatic group (CMV N = 1, Haemophilus influenzae N = 2), but in none of 12 specimens from the asymptomatic group. Adverse effects encountered were minor. Four symptomatic patients with negative induced sputum samples underwent bronchoalveolar lavage, and no further organisms were identified. Sputum induction can be a useful adjunct to the diagnosis of respiratory pathogens in this group of patients.

Unique differences in infectivity and seroreactivity of Toxoplasma harvested from mice infected for different lengths of time.

For use in experiments, Toxoplasma of the RH strain are usually harvested from mouse peritoneal cavities 48 hr (2-day Toxoplasma) or more after intraperitoneal inoculation. In this report we show that Toxoplasma harvested at 24 hr (1-day Toxoplasma) after inoculation are much more infective for and replicate to a greater degree within mouse resident peritoneal macrophages in vitro and are much more resistant to the cidal activity of activated mouse peritoneal macrophages and resident rat peritoneal macrophages than are 2-day Toxoplasma. Ingestion of 1-day Toxoplasma by macrophages did not trigger the respiratory burst as measured by reduction of nitroblue tetrazolium (NBT), but coating 1-day Toxoplasma with specific antibody did result in reduced NBT. However, coating 1-day Toxoplasma with specific antibody did not markedly decrease infectivity for macrophages in vitro, unlike decreased infectivity observed when 2-day Toxoplasma are coated with specific antibody. Use of 1-day Toxoplasma in the dye test resulted in a 5-fold decrease in titer of specific antibody in human sera. Use of Toxoplasma harvested 24 hr after infection may serve as a new tool to probe virulence factors of Toxoplasma and of host cells' antimicrobial mechanisms.

Chronic nicotine ingestion and atrial fibrillation.

Paroxysmal atrial fibrillation occurred in a fit 35 year old man who consumed large doses of nicotine chewing gum (Nicorette Leo) over a prolonged period.

In vivo and in vitro activation of alveolar macrophages by recombinant interferon-gamma.

In vivo administration of recombinant interferon-gamma (rIFN-gamma) was previously shown to result in activation of the microbicidal activities of peritoneal macrophages (PM phi). Because macrophages at different anatomical sites vary in their functional capacities, we considered it of interest to determine whether administration of murine rIFN-gamma, either in vitro or in vivo, can enhance the microbicidal activity of resident alveolar macrophages (AM phi) and to compare the effects of rIFN-gamma on AM phi and PM phi. After incubation in vitro with rIFN-gamma, the antimicrobial activities of both murine AM phi and PM phi were enhanced, as assessed by their ability to inhibit replication of the intracellular parasite, Toxoplasma gondii. This effect was dose dependent for AM phi over a range of 0.1 to 1 U/ml and for PM phi over a range of 0.5 to 1000 U/ml. In this assay, the minimum dosage required for in vitro activation of AM phi was one-half that required for activation of PM phi, suggesting a greater sensitivity of AM phi to the in vitro activity of rIFN-gamma. Macrophages from both anatomical sites were also activated when rIFN-gamma was administered in vivo. This effect was dose dependent over a range of 10(3) to 10(5) U/mouse. Freshly harvested AM phi and PM phi from mice injected 24 hr earlier with 10(4) U rIFN-gamma by either the i.v. or i.p. routes markedly inhibited intracellular multiplication of Toxoplasma. In contrast, AM phi and PM phi from control mice permitted fourfold to ninefold increases in numbers of intracellular Toxoplasma. The anti-toxoplasma activity of AM phi and PM phi gradually diminished over a period of 3 days when assayed at successive 24 hr periods after a single i.v. injection of rIFN-gamma. At 3 days after injection, a substantial loss of anti-toxoplasma activity was observed with PM phi as compared with controls; residual anti-toxoplasma activity was still demonstrable in AM phi at 3 days. These results demonstrate that in vitro as well as in vivo treatment with rIFN-gamma confers on AM phi an enhanced antimicrobial activity. These findings provide a rationale for evaluating rIFN-gamma in the treatment of pulmonary infections, especially those due to opportunistic pathogens against which AM phi play a major role in host defense.

Use of opioid analgesics in a patient with chronic abdominal pain.

Pethidine is the most commonly used opioid in hospitals in the UK, but it lacks potency, has a short duration of action and a narrow therapeutic index. These points are illustrated by a case history of a patient prescribed pethidine for chronic abdominal pain. Misplaced fears of the side-effects of morphine result in its underuse in the management of chronic pain with consequential restriction of patients' functional ability.

Do asthmatics suffer bronchoconstriction during rapid eye movement sleep?

Many patients with asthma are troubled by nocturnal wheeze. The cause of this symptom is unknown, but sleep is an important factor. A study was carried out to determine whether nocturnal bronchoconstriction is related to any specific stage of sleep. Eight asthmatics with nocturnal wheeze and eight control subjects performed forced expiratory manoeuvres immediately after being woken from rapid eye movement (REM) or non-REM sleep, wakings being timed to differentiate temporal effects from those related to the stage of sleep. The control subjects showed no significant temporal bronchoconstriction or bronchoconstriction related to the stage of sleep. All patients showed bronchoconstriction overnight, the mean peak expiratory flow rate falling from 410 (SEM 50) 1/min before sleep to 186 (49)1/min after sleep. After the patients had been woken from REM sleep the forced expiratory volume in one second was on average 300 ml lower (p less than 0.02) and peak expiratory flow rate 45 1/min lower (p less than 0.03) than after they had been woken from non-REM sleep. As wakenings from REM sleep were 21(8) minutes later in the night than those from non-REM sleep multivariate analysis was performed to differentiate temporal effects from those related to the stage of sleep. This showed that the overnight decreases in forced expiratory volume in one second and peak expiratory flow rate were significantly related both to time and to REM sleep. This study suggests that asthmatics may suffer bronchoconstriction during REM sleep.