Faculty Bibliography

The effect of circuit training on blood pressure (BP) and strength were evaluated for six months in 16 middle-aged (means = 55.8 years) men in a metropolitan cardiac rehabilitation program. Circuit training consisted of 12 to 20 repetitions at 30% to 40% of one repetition maximum on 12 Nautilus exercises with one-minute rests between exercises. This strength conditioning was supplemental to the patients' aerobic exercise. Five of the patients had myocardial infarctions, six had coronary artery bypass grafts, two had ventricular arrhythmias, one had angioplasty, and two had a complex of other cardiac conditions. Average height, weight, and body fat for the 16 patients were 179.3 cm, 82.4 kg, and 24.6%, respectively. Blood pressure (BP) data indicated no change in mean systolic or diastolic values during actual circuit training sessions (initial = 122/77 mmHg, mid = 124/78 mmHg, end = 122/76 mmHg). These data were compared with corresponding sets of BP at three and six months of training and no significant differences were seen. In no instance did circuit training appear to elevate a patient's BP above clinically acceptable levels for controlled hypertension. In the six months, significant increases in strength were observed with a mean increment of 8.2 kg or 22% for all 12 exercises. No changes occurred in body weight or percentage of fat. For selected patients in cardiac rehabilitation programs, a carefully supervised, long-term program of low-resistance strength training appears to be safe with regard to BP response, and beneficial in terms of strength gain.

Neutrophils (polymorphonuclear leucocytes) are the principal cell of the host defence system. Consequently, if periodontal pathogen-derived substances in the gingival crevice significantly inhibit their function, they could shift the bacterial-host balance in favour of the bacteria. The hypothesis that ammonia can inhibit neutrophil function was tested. Ammonia was specifically selected because periodontal pathogens produce substantial amounts of ammonia. The findings indicated that ammonia can inhibit neutrophil phagocytosis, degranulation and oxygen metabolism. Ammonia decreased the total number of phagocytosing polymorphonuclear neutrophils (66% of control) and also decreased degranulation (61% of control). Ammonia decreased oxygen metabolism of both resting and stimulated neutrophils (33 and 42% of control, respectively). These observations support the hypothesis that ammonia can inhibit the function of polymorphonuclear leukocytes. They suggest that the presence of ammonia in the gingival crevice may increase the risk of development of periodontal disease.

Forward-angle light scatter (FALS) and right-angle light scatter (RALS) are commonly employed to discriminate between leukocyte subclasses. Recently the application of RALS has expanded, and it is now also used as an indicator of neutrophil actin polymerization. In this communication we critically examine the relationship of RALS to changes in cytoskeletal actin. The data indicate that agonists which stimulate an increase, a decrease, or no change in F-actin content can all stimulate a biphasic change in RALS. We therefore conclude that changes in RALS can occur independently of changes in F-actin content. This leads us to suggest that caution must be taken when interpreting RALS data in relation to changes in F-actin. Furthermore, the data also support the idea originally proposed by Yuli and Snyderman (J Clin Invest 73:1408-1417, 1984), that RALS may be an exceptionally sensitive indicator of cell activation.

Ammonia is a bacterial metabolite which is commonly used to alter cytoplasmic and lysosomal pH of eukaryotic cells. Here we examine its effect on external N-formyl peptide receptors of human neutrophils. Ammonia does not affect the number of N-formyl peptide receptors on the cell surface, nor the association of the ligand-receptor complex with the cytoskeleton. However, ammonia causes a marked decrease in the affinity of the chemotactic peptide receptor for its ligand. The Kd of untreated cell for the chemotactic peptide was 0.65 +/- 0.06 nM, whereas that of ammonia treated cells was 1.02 +/- 0.10 nM (Mean +/- SEM, N = 6). These results suggest that ammonia can affect external as well as internal cellular components. Since ammonia is used to alter lysosomal and cytoplasmic pH, and is a metabolite of common bacterial pathogens, these results bear directly on its use in cell biology and on its potential as a virulence factor.