François Haas

Role of the Mast Cell in the Pulmonary Pressor Response to Hypoxia

This study investigated the role of the mast cell in the pulmonary arterial pressor response to hypoxia. We found that pulmonary arteries 50-500 mu in diameter have a predictable distribution of perivascular mast cells; that such pulmonary mast cells are degranulated in vivo during alveolar hypoxia; that hypoxia releases histamine from mast cells isolated from the peritoneal cavity without apparent injury to the cells; and that histamine is released from the lung of intact guinea pigs during alveolar hypoxia, with the rise in pulmonary vascular resistance during this period proportional to the amount of histamine released. These data point to the perivascular pulmonary mast cell in the rat and guinea pig as an important structure in the mediation of the pulmonary pressor response to hypoxia, even though the responsible humoral vasoconstrictor released from such a cell may not be histamine, or histamine alone.

Chronotropic incompetence, beta-blockers, and functional capacity in advanced congestive heart failure: Time to pace?

Chronotropic incompetence (CI) is often seen in subjects with chronic congestive heart failure (CHF). The prevalence of CI, its mechanisms and association with beta‐blocker use as well as exercise capacity have not been clearly defined.

Diaphragmatic Function Following Cervical Cord Injury: Neurally Mediated Improvement

Vital capacity measurements from 36 people rendered quadriplegic by traumatic cervical cord injuries generally increased during the first ten months after injury, indicating spontaneous improvement in respiratory muscle function. Reasoning that a renewal of neural supply to the diaphragm would probably be accompanied by a parallel renewal of neural supply to other muscles having adjacent motor pathways, the present study compared vital capacity measurements with concomitant muscle function evaluations from 20 of these people. Qualitatively, increases in vital capacity were invariably accompanied by increases in the function of a group of muscles (primarily of the shoulder and upper arm) having some segmental innervation in common with the diaphragm (C3-C5) but were only sometimes accompanied by increases in the function of a group of muscles (primarily of the forearm and wrist) having segmental innervation below that of the diaphragm (C6-C8). These findings suggest that the spontaneous improvement in vital capacity observed in quadriplegic people is mediated in part by corresponding improvement in the neural supply to the diaphragm. Quantitatively, however, linear regression analysis indicated that neither the rate nor the absolute amount of improvement in vital capacity could be predicted with any reliability from pulmonary function tests, neurologic examinations, or muscle function evaluations performed in the early stage of recovery.

Effect of Milk Ingestion on Pulmonary Function in Healthy and Asthmatic Subjects

Since Maimonides, it has been common in folk medicine to proscribe milk for asthmatics because its putative stimulation of mucus production can exacerbate asthma symptoms. A literature review, however, failed to reveal any data supporting this notion. We, therefore, compared the effects of ingesting 16 oz. of whole milk (16 g lipid), skim milk (2 g lipid), and water (each on a separate day) on: (1) forced expiratory volume in 1 second (FEV1), (2) forced expiratory flow at 50% of vital capacity (V50), and (3) pulmonary diffusing capacity (DLCO) in 11 asthmatic and 10 nonasthmatic subjects. Measurements were taken at 30 minute intervals for 3 hours. The two milk types did not significantly change FEV1 or V50 in either group, indicating that the amount ingested did not change airway resistance sufficiently to alter airflow parameters. In the asthmatic group, however, DLCO decreased progressively over the 3 hours by 6.8 +/- 1.4% (mean +/- SE) per hour after whole milk (maximum reduction = 21 +/- 1.4%) but not after water or skim milk. In the nonasthmatic group, no significant effects were observed on DLCO after any of the liquids. These data suggest that milk lipids can disturb gas exchange in asthmatic patients.

Complications after cardiac operations in patients with severe pulmonary impairment

The postoperative courses of 39 patients with severe lung disease (31 with obstructive disease and 8 restrictive) who underwent a cardiac operation were retrospectively reviewed. The stay in the intensive care unit of the study group was 7.9 +/- 10.3 days (mean +/- standard deviation) compared with 2.4 +/- 3.9 days for the control group (100 patients with less impaired pulmonary function) (p less than 0.001). The study group also had a greater number of valve replacements than did the control group (p less than 0.01). Patients with obstructive disease had more respiratory complications than did patients with restrictive disease (p less than 0.05). There were 21 cases of atelectasis. Effusions were noted in 11 patients. Ten patients had bronchospasm. Bronchial secretions were a major problem in 6 patients. Pneumonia developed in 4 patients, and pneumothorax occurred in 3 others. The two in-hospital deaths were not directly related to pulmonary complications. Our findings indicate that (1) patients with severe lung impairment generally do well after a cardiac operation but have more postoperative pulmonary complications than patients with less impairment; (2) patients with restrictive pulmonary disease appear to fare better than those with obstructive disease; (3) pulmonary function tests can alert the clinician to the possible risk of postoperative complications, but they cannot, by themselves, be used to exclude patients from operation; and (4) patients with severe pulmonary impairment facing valve replacement are at greater risk of pulmonary complications than patients having other types of cardiac surgical intervention.

Hippocampal blood flow in normal aging measured with arterial spin labeling at 3T

Due to methodological difficulties related to the small size, variable distribution of hippocampal arteries, and the location of the hippocampus in the proximity of middle cranial fossa, little is known about hippocampal blood flow (HBF). We have tested the utility of a pulsed arterial spin labeling sequence based on multi‐shot true fast imaging in steady precession to measure HBF in 34 normal volunteers (17 women, 17 men, 26–92 years old). Flow sensitivity to a mild hypercapnic challenge was also examined. Coregistered 3D MPRAGE sequence was used to eliminate from hippocampal and cortical regions of interest all voxel with <75% of gray matter. Large blood vessels were also excluded. HBF in normal volunteers averaged 61.2 ± 9.0 mL/(100 g min). There was no statistically significant age or gender effect. Under a mild hypercapnia challenge (end tidal CO2 pressure increase of 6.8 ± 1.9 mmHg over the baseline), HBF response was 14.1 ± 10.8 mL/(100 g min), whereas cortical gray matter flow increased by 18.0 ± 12.2 mL/(100 g min). Flow response among women was significantly larger than in the men. The average absolute difference between two successive HBF measures was 3.6 mL/(100 g min) or 5.4%. The 3T true fast imaging in steady precession arterial spin labeling method offers a HBF measurement strategy that combines good spatial resolution, sensitivity, and minimal image distortions. Magn Reson Med, 2010.

Treadmill exercise training in chronic obstructive pulmonary disease

Eight men and six women with severe chronic obstructive pulmonary disease (COPD) performed a pulmonary function test and a treadmill exercise stress test before and after an individualized training program, which nominally consisted of three 20-minute sessions of treadmill exercise per week for five consecutive weeks. Training sessions were terminated before 20 minutes if there were subjective complaints, or if the subjects heart rate reached 80% of the maximum heart rate observed during the pretraining stress test. This program failed to improve any of the pulmonary function test parameters (lung volumes, airflows, maximum voluntary ventilation, and resting levels of blood gases) and failed to improve most exercise stress test parameters (maximum oxygen consumption and carbon dioxide production, respiratory exchange ratio, and heart rate at termination of exercise). This program, however, did increase the groups average stress test time from 9.0-13.7 minutes (p less than 0.001) and increased the total external work (calculated from the sum of its vertical and horizontal components) from 3.5-6.8kcal (p less than 0.01). Eight of the 11 subjects who initially received 2L/min of 100% oxygen, via a nasal cannula, to alleviate dyspnea and to promote endurance were completely weaned from supplemental oxygen by the end of the training program. These findings demonstrate that a treadmill exercise program based on stress test data can increase the efficiency (external work per unit of oxygen consumed) and thus, the exercise tolerance, of persons with severe COPD.

German science and black racism—roots of the Nazi Holocaust

The Nazis cornerstone precept of “racial hygiene” gave birth to their policy of “racial cleansing” that led to the murders of millions. It was developed by German physicians and scientists in the late 19th century and is rooted in the periods Social Darwinism that placed blacks at the bottom of the racial ladder. This program was first manifested in the near‐extermination of the African Herero people during the German colonial period. After WWI, the fear among the German populace that occupying African troops and their Afro‐German children would lead to “bastard‐ization” of the German people formed a unifying racial principle that the Nazis exploited. They extended this mind‐set to a variety of “unworthy” groups, leading to the physician‐administered racial Nuremberg laws, the Sterilization laws, the secret sterilization of Afro‐Germans, and the German euthanasia program. This culminated in the extermination camps.—Haas, F. German Science and Black Racis.—Haas, F. German Science and Black Racism—Roots of the Nazi Holocaust. FASEB J. 22, 332–337 (2008)

Servo Control of Atrial and/or Arterial Blood Pressures in Experimental Animals

A control system employing two adjustable reservoirs for the independent regulation of atrial and/or arterial blood pressures simultaneously at both sides of the heart is described. Two servo-motors position these reservoirs and thereby automatically regulate atrial filling and hence ventricular output to produce various controlled pressure wave forms.