A deep stop during decompression from 82 fsw (25 m) significantly reduces bubbles and fast tissue gas tensions.

In spite of many modifications to decompression algorithms, the incidence of decompression sickness (DCS) in scuba divers has changed very little. The success of stage, compared to linear ascents, is well described yet theoretical changes in decompression ratios have diminished the importance of fast tissue gas tensions as critical for bubble generation. The most serious signs and symptoms of DCS involve the spinal cord, with a tissue half time of only 12.5 minutes. It is proposed that present decompression schedules do not permit sufficient gas elimination from such fast tissues, resulting in bubble formation. Further, it is hypothesized that introduction of a deep stop will significantly reduce fast tissue bubble formation and neurological DCS risk. A total of 181 dives were made to 82 fsw (25 m) by 22 volunteers. Two dives of 25 min and 20 min were made, with a 3 hr 30 min surface interval and according to 8 different ascent protocols. Ascent rates of 10, 33 or 60 fsw/min (3, 10, 18 m/min) were combined with no stops or a shallow stop at 20 fsw (6 m) or a deep stop at 50 fsw (15 m) and a shallow at 20 fsw (6 m). The highest bubbles scores (8.78/9.97), using the Spencer Scale (SS) and Extended Spencer Scale (ESS) respectively, were with the slowest ascent rate. This also showed the highest 5 min and 10 min tissue loads of 48% and 75%. The lowest bubble scores (1.79/2.50) were with an ascent rate of 33 fsw (10 m/min) and stops for 5 min at 50 fsw (15 m) and 20 fsw (6 m). This also showed the lowest 5 and 10 min tissue loads at 25% and 52% respectively. Thus, introduction of a deep stop significantly reduced Doppler detected bubbles together with tissue gas tensions in the 5 and 10 min tissues, which has implications for reducing the incidence of neurological DCS in divers.     

Superior Transseptal Approach for Surgical Removal of Left Atrial Myxoma

A bstract Eight patients (4 men, 4 women), mean age 51 years, referred to our Institution for left atrial myxoma underwent removal of the tumor through a superior transseptal approach. All patients in sinus rhythm with normal conduction time. The myxomas were localized in the fossa ovalis (3 cases), interatrial septum (2 cases), left appendage (2 cases), and mitral annulus (1 case). One patient died in hospital after emergency operation for low-output syndrome complicated by septic shock. All other patients had an uneventful postoperative course. Atrial arrhythmias did not represent a major postoperative complication. Transient PR interval elongation was occasionally seen. Electrophysiological studies showed normal sinus node function. At 6 months following operation, patients were evaluated with transeso-phageal echocardiography. There was no tumor recurrence. There were no episodes of arrhythmia in 24-hour electrocardiographic monitoring, and all patients were in NYHA Class I. We believe that the superior transseptal approach gives optimal exposure of the left atrial cavity, overcoming all difficulties related to a small left atrium which is an usual pattern in left atrial myxomas.     

Aging impairs membrane potential responsiveness as well as opening of voltage and ligand gated Na+ channels in human lymphocytes

Depolarizing effects of increasing concentrations of extracellular K(+), as well as the repolarizing effect of bretylium tosylate (BT) were evaluated in human lymphocytes from young and elderly volunteers. Cells from elderly volunteers were less responsive to depolarization induced by increased extracellular potassium concentrations than those from young volunteers. Upon a near complete depolarization induced by 140 mM K(+) in the extracellular space, a significant amount of non-responding cells were found in samples from elderly volunteers. BT, which opens the otherwise silent Na(+) channels of partially depolarized cells, with subsequent activation of the Na(+)-K(+) pump (Pieri et al., 1989). repolarized both young and old lymphocytes. However, the degree of the repolarization was only 40% in the case of lymphocytes from elderly volunteers than from that of the young. It is suggested that an increase of membrane microviscosity, characteristic of old cells, may be at least partially responsible for the decreased responsiveness of plasma membrane functions which were observed.     

Alteration of acylphosphatase levels in familial Alzheimer''s disease fibroblasts with presenilin gene mutations

Acylphosphatase (ATPase), an enzyme that modulates the activity of Ca²⁺-ATPase by hydrolysing its phosphorylated moiety, has been found to be significantly higher in cultured skin fibroblasts from donors affected by early onset familial Alzheimer's disease (EOFAD) with PS-1 and PS-2 gene mutations. Of the two known isoenzymes of acylphosphatase, only the erythrocyte one accounts for the total increase in activity. No relevant alteration was observed in phosphotyrosine phosphatase activity (PTPase), in Ca²⁺-ATPase and Na⁺,K⁺-ATPase activities of the same cells as compared to age-matched controls. This finding could suggest a possible explanation for the calcium-dependent biochemical alterations previously described in Alzheimer's disease fibroblasts.     

Peripheral T-cell lymphomas. Clinico-pathologic study of 168 cases diagnosed according to the R.E.A.L. Classification

Background: One hundred sixty-eight peripheral T-cell lymphomas (PTCLs)were reviewed according to the Revised European–American Lymphoma (R.E.A.L.)Classification.Patients and methods: The cases, originally diagnosed on the basis of theUpdated Kiel Classification (UKC), were all provided with histologicalpreparations, immunophenotype, clinical information, and follow-up data. Theslides were reclassified by five observers, who integrated the R.E.A.Lcriteria with cell size measurements. The prognostic value of clinical andpathologic findings was assessed by univariate and multivariate analysis.Results: The R.E.A.L. Classification was reproducibly applied by all of theobservers. Clinically, anaplastic large cell lymphomas (ALCLs) differed fromthe remaining PTCLs by mean age (29.5 vs. 52.9 years), bulky disease(52.3% vs. 11.3%; P = 0.000), mediastinal mass (52.7% vs.32%; P = 0.004), and disease-free survival (68.0% vs.38.2%; P = 0.0001). Although each histological type displayed specificclinical aspects, PTCLs other than ALCL were basically characterised by a poorclinical outcome which was not influenced by the UKC malignancy grade. Atmultivariate analysis, the risk of a lower complete remission rate was relatedto bulky disease (P = 0.001), histologic group (non-ALCL) (P = 0.01), andadvanced stage (III–IV) (P = 0.0002).Conclusions: The present study supports the classification of T-celllymphomas proposed by the R.E.A.L. scheme.     

Transthoracic 2D echo color Doppler assessment of internal mammary artery to left anterior descending coronary artery graft

For noninvasive evaluation of anatomy and flow characteristics of internal mammary artery graft (IMA-graft), 2D echo-Color-Doppler (CDE) was performed in 60 patients (54 M, 6 F, mean age 54.1±6.9 y), who underwent coronary angiography 20.1 ±13 months after a coronary artery bypass graft (CABG).CDE was performed, using an echocardiographic unit equipped with a 5 MHz linear transducer.In all patients, measurements of IMA-graft diameter (mm), and peak systolic and diastolic flow velocity (cm/sec) were obtained at baseline and also in 16 patients after dipyridamole infusion (0.54 mg/Kg/min) and in 10 patients after sublingual nitroglycerin (NTG) (0.4 mg). Angiography showed the IMA-graft patency in 58/60 patients (96.8%).A typical biphasic flow was displayed by CDE in 49/58 patients (84.4%) with angiographic patency.Dipyridamole infusion increased both IMA-graft diameter and peak diastolic flow velocity (PDFV) from 2.28 ±0.51mm to 2.9 ±0.42mm and from 19.4 ±6.2 cm/sec to 93.9 ±29 cm/sec, respectively (p<0.0001).No significant modifications of peak systolic flow velocity (PSFV) were observed.NTG increased PDFV from 29.11 ±8 cm/sec to 41.88 ±7.20 cm/sec (p<0.005), while diameter and PSFV showed no statistically significant modifications.CDE is a useful diagnostic tool for noninvasive evaluation of IMA-graft patency both early after surgery and during long-term follow-up. CDE pharmacological stress improves the sensibility of the technique and it can provide indirect information about pathophysiology of recipient coronary vessel.     

Melatonin is an efficient antioxidant

We have compared the peroxyl radical scavenger ability of melatonin with that of vitamin E, ascorbic acid (As.A.), reduced glutathione (GSH) and mannitol. All the antioxidants, except mannitol, prevented the lysis of human erythrocytes exposed to an azo-initiator of peroxyl radicals (2,2'-azo-bis(2-amidinopropane)dihydrochloride) at 37 degrees C. The percentage of this inhibition of erythrocyte lysis varied with the concentration of antioxidants, but the efficiency was melatonin > vitamin E > As.A. > GSH. Based on the assumption that each molecule of vitamin E scavenges two peroxyl radicals, the scavenging capacity of melatonin was four peroxyl radicals/molecule.     

A sodium channel opener inhibits stimulation of human peripheral blood mononuclear cells.

The role of membrane potential changes in T cell activation was studied on human peripheral blood lymphocytes stimulated with phytohemagglutinin. Addition of bretylium tosylate, a sodium channels opener, to PHA treated lymphocytes modified the membrane potential and consequently blocked cell activation in a dose-dependent fashion. BT was non-toxic even in long-term (72 hr) incubations. It was reversibly removable, and the removal restored the stimulatory effect of PHA. 3H-thymidine incorporation was blocked if BT was present during the first 20-24 hr of the mitogenic activation. The later BT was added after PHA, the less inhibition of proliferation was observed. BT hyperpolarized the lymphocytes also in the presence of PHA. BT hindered the depolarizing effect of high extracellular potassium concns. The sustained polarized state of the lymphocytes did not influence the intracellular calcium increase upon PHA treatment. IL-2 and transferrin receptor expression was not hindered by BT during PHA stimulation of lymphocytes. Addition of rIL-2 did not abolish the inhibitory effect of BT. According to cell-cycle analysis BT arrested the majority of the cells in G1 phase. It is suggested that cell activation demands the flexible maintenance of a relatively narrow membrane potential "window". Any sustained and significant hyper-, or depolarization, may dramatically decrease the effectivity of transmembrane signalling.