B-type natriuretic peptide after open-water and hyperbaric chamber exposure to 10 msw

INTRODUCTION

Hyperbaric environment exposure in humans has cardiovascular effects mainly characterized by an increase in afterload and a decrease in cardiac output. In a previous study we did not find B-type natriuretic peptide (BNP) changes in healthy volunteers exposed to hyperbaric oxygen while other authors documented a significant increase in N-terminal pro-BNP after scuba diving. On the basis of these data we hypothesized that dry hyperbaric exposure and scuba diving could have different effects on BNP secretion.

METHODS

Nine healthy volunteers performed a 1-h open-sea air dive at 10 m depth (T); a few days later they were compressed in air in a hyperbaric chamber (CT) using the same dive profile. Three venous blood samples were drawn for each session: before starting the dives (T0 and CT0), immediately after exiting the water and the chamber (T1 and CT1), and 5 h later (T2 and CT2).

RESULTS

A significant increase in plasma BNP was found with respect to baseline conditions after scuba diving both at T1 (median increment +32.69% [interquartile range +25.62 to +65.35%]) and at T2 (+28.03% [+23.08 to +38.92%]) while no differences were documented after the same dive in dry conditions either at CT1 (+1.34% [-17.57 to +33.55%]) or at CT2 (0.00% [17,67 to +21.62%]).

DISCUSSION

These preliminary findings show that scuba diving and dry hyperbaric exposure, although at the same environmental pressure, cause different effects on ventricular loads in healthy subjects.

Red cell and core temperature in spelunking

Alpine spelunking is practiced in darkness, isolation, cold and high humidity. In this paper we study the acute haematological effects of prolonged strenuous activity in five spelunkers who spent about 20 hours in a 700-meter deep cave without resting much or sleeping. On four occasions, we measured their red cell counts, haemoglobin, mean corpuscular volume and percentage changes of plasma volume. We also measured their rectal temperature to estimate, in the limits of this parameter, thermoregulatory response. After the spelunkers descended 5 hours to the bottom of the cave, we detected, in all of them, a significant increase in red cell counts and haemoglobin and a drop in mean corpuscular volume and plasma volume. The day after recovery, we found a significant drop in all red cell parameters and a rise in plasma volumes. Rectal temperatures peaked at the exit. These findings suggest that alpine spelunking induces an initial haemoconcentration (bottom of the cave) followed by a haemodilution (the day after recovery). Sport anaemia was not detected. The rise of rectal temperature suggests that spelunking is a very strenuous sport with possible transpiration problems.

Hormonal responses to a long duration exploration in a cave of 700 m depth

We studied the hypothalamus-pituitary adrenocortical, hypothalamus-pituitary and hypothalamus-pituitary thyroid system responses to a long duration activity (about 20 h) practiced in a demanding environment, characterized by darkness, low temperature and high humidity, namely alpine potholing. We performed four blood drawings in five elite potholers: (1) the morning before the performance, (2) at the bottom of the cave (-700 m), (3) at the end of the ascent, and (4) after 24 h of recovery. Two blood drawings as controls were performed on the same potholers, at the same resting time and with the same experimental procedures as the previous ones. Friedman two-way ANOVA test evidenced significant changes through the different time intervals for detrended (i.e., test values minus control values) growth hormone (GH) (P = 0.003), detrended cortisol (P = 0.004) and FT4 (P = 0.002), while this was not true for TSH and FT3. Successively pairwise comparisons were done both through the different time intervals and between test and control values. The rise of GH values during the performance underlines the great intensity and long duration characteristic of potholing as well as the possibility that the climbing sit harness can cause problems due to vascular hypo-perfusion. Cortisol data, peaking before entering the cave, suggest that there was a marked anticipatory stress reaction followed by less stressing phase during the performance. Finally, the rise of FT4 is likely due to the typical increase of free fatty acids that usually occurs during endurance exercise.

Muscular damage and intravascular haemolysis during an 18 hour subterranean exploration in a cave of 700 m depth

OBJECTIVE

To verify presence and severity of muscular and/or intravascular damage during a subterranean exploration of long duration.

METHODS

We measured serum levels of creatine kinase (CK) and lactate dehydrogenase (LDH) as markers of muscular damage. We also measured haptoglobin as a marker of intravascular haemolysis, and platelets and leucocytes as markers of inflammation.

RESULTS

We found in all the participants an increase in CK, LDH, and platelets and leucocytes (mainly due to neutrophilia and monocytosis), and a decrease in the level of haptoglobin and circulating lymphocytes.

CONCLUSIONS

The observed data suggest that continuous effort during long alpine subterranean explorations, environmental conditions, sleep deprivation, multiple impacts on rocks, and compression caused by bindings of the caving harness cause muscle damage, intravascular haemolysis, inflammation response, and immunological changes.

Eosinophil peroxidase deficiency: morphological and immunocytochemical studies of the eosinophil-specific granules

Five eosinophil peroxidase (EPO)-deficient subjects were identified from 131,000 peripheral blood samples examined for routine automated analysis. The EPO-deficient eosinophils of these subjects met the main criteria established for EPO deficiency: absent or strongly decreased reaction for peroxidase, absent or strongly decreased staining with Sudan Black, and an increased ratio of the granule core volume to the total granule volume. In this report we show that this granule alteration is caused mainly by a decrease of its volume, particularly of the matrix, and that two other matrix proteins, eosinophil cationic protein and eosinophil derived neurotoxin, appear to be present in normal amounts in the EPO-deficient granules.

Clinical and laboratory evaluation of the myeloprotective effect of medroxyprogesterone acetate in head and neck cancer

The action of high-dose medroxyprogesterone acetate (MPA) was studied by analysing the behaviour of colony-forming-unit granulocyte-macrophage (CFU-GM) during chemotherapy. 21 non-pretreated men with locally advanced carcinoma of the head and neck were randomised into two arms: A (11 patients) received three alternating cycles of cisplatin, 5-fluorouracil (CF)/cisplatin, methotrexate, bleomycin, vincristine and then CF every 4 weeks and B (10 patients) were treated with the same schedule plus 1000 mg per day of MPA. MPA was administered 14 days before the start of chemotherapy (day 0) and continued daily up to the 90th day. Bone marrow was harvested in arm A on days 0, +14 and +90, and in B, also on day -14. There was diverse CFU-GM behaviour in the two arms on the 14th day. These data support the hypothesis that the myeloprotective effect of MPA is due to induction of a mitotic rest in the stem cells, which protects them from drug action.

Oxidation of homovanillic acid as a selective assay for eosinophil peroxidase in eosinophil peroxidase-myeloperoxidase mixtures and its use in the detection of human eosinophil peroxidase deficiency

Biochemical assays for peroxidase activity do not usually distinguish between different peroxidases. The guaiacol assay, for example, which is one of the most commonly used assays for peroxidase activity, is sensitive to both eosinophil peroxidase (EPO) and the peroxidase of neutrophils, i.e., myeloperoxidase (MPO), thus preventing distinction of the two peroxidases in mixed neutrophil-eosinophil populations. In this paper we describe a simple and sensitive method for selective assays of EPO in EPO-MPO mixtures or mixed populations of neutrophils and eosinophils. The method is based on the peroxidase-mediated oxidation of homovanillic acid (HVA) under appropriate assay conditions in which EPO is still very active in catalyzing the reaction whilst MPO-mediated HVA oxidation is almost undetectable. Optimal assay conditions were as follows: pH 10.5, 10 microM hydrogen peroxide, 0.8 mM HVA and an incubation time of 120 min at 37 degrees C. Under these conditions the assay permits EPO activities as low as 0.025 guaiacol U/ml to be measured even in the presence of 0.175 guaiacol U/ml of MPO. In mixed neutrophil-eosinophil cell suspensions the test permits the detection of as few as 5 X 10(3) eosinophils even in the presence of about 700 X 10(3) neutrophils (eosinophils: neutrophils ratio 1:140) with no appreciable interference by the latter cells. The method described here has been applied to studies of human EPO deficiency and proved to be successful in the identification of individuals with partial EPO deficiency, which is not feasible with non quantitative methods (for example, cytochemistry) or unselective biochemical assay of peroxidase activity.