Acute inferior vena cava thrombosis. Early results of heparin therapy

STUDY OBJECTIVE

To determine, during heparin therapy, the embolic risk associated with acute inferior vena cava thrombosis compared with noncaval thrombosis.

DESIGN

Prospective controlled study.

SETTING

University-affiliated general hospital.

PATIENTS

Of 68 consecutive patients considered, 18 with cavographically proved inferior vena cava thrombosis and 45 with phlebography-proved noncaval proximal thrombosis met all other eligibility criteria and completed the study.

INTERVENTIONS

All patients received adjusted continuous IV heparin therapy for ten days.

MEASUREMENTS AND RESULTS

All 63 patients underwent systematic baseline and "day 10" perfusion lung scanning and phlebocavography. None suffered pulmonary embolism within the ten days, but 11/63 patients showed thrombus extension on day 10 phlebocavograms. Retrospectively, no significant difference could be found between the groups with and without extension.

CONCLUSIONS

(a) The early embolic risk associated with heparin-treated venous thromboses appears low and does not seem to depend on the location (caval or more peripheral) of venous clots. (b) Thrombus extension may occur in spite of apparently "adequate" anticoagulation with heparin.

Hypotensive and peripheral vascular effects in healthy volunteers of repeated oral administration of pinacidil

The hypotensive and peripheral vascular effects of two different oral formulations of pinacidil were investigated in twelve healthy male volunteers. Arterial blood pressure, heart rate and calf blood flow were measured on Days 1 and 7. The vasodilator activity of both formulations was confirmed by a significant increase in calf blood flow on both days, which was correlated with a significant decrease in diastolic blood pressure. There was no differences between the tablet and the pellet.

Interleukin-2 induces proliferation of T lymphocyte mutants lacking protein kinase C

We have identified a murine T lymphocyte clone that apparently lacks diacylglycerol- and phospholipid-activated protein kinase C (PKC): cell extracts do not display phosphatidylserine, Ca2+, or phorbol ester-dependent phosphotransferase activity; the enzyme was not detected in immunoblots with PKC-specific antibodies; phorbol ester binding sites are not detectable in intact cells; and activators of PKC do not stimulate proliferation or Na+/H+ exchange in intact cells. Only PKC beta mRNA was detected in normal murine T lymphocytes. The mutant T lymphocytes contained amounts of 4.4 kb PKC beta message similar to those in normal murine lymphocytes, but the 2.9 kb and 1.2 kb messages found in normal lymphocytes were barely detectable. No abnormalities were detected on Southern analysis, suggesting that the abnormality may be at the level of message splicing or stability. Since PKC-deficient cells proliferate in response to the T lymphocyte growth factor, interleukin-2, we conclude that activation of PKC is not essential for the growth-promoting action of interleukin-2.

The cell biology of ras-induced transformation: insights from studies utilizing an inducible hybrid oncogene system

The c-Ha-ras oncogene has been implicated as a causative agent in the development of tumors in humans as well as mice. The molecular nature of the ras-induced tumorigenic process remains unclear, however. To address this question directly we have constructed a cell line which carries a zinc-inducible metallothionein-ras hybrid oncogene, transformant 212. Upon exposure to zinc for 24-48 hr, 212 cells assume a highly transformed morphology, concomitant with the induction of ras-expression. Natural killer cells constitute a subpopulation of lymphoid effector cells which have for a long time been hypothesized to be involved in the earliest stages of antitumor surveillance. Central to this hypothesis is the prediction that NK sensitivity arises during cellular transformation. By carrying out cytotoxicity assays against the 212 transformant, we showed that, indeed, increased sensitivity to NK-mediated lysis correlated with expression of the ras oncogene, which is consistent with the above hypothesis. We then addressed the question of the biochemical mechanism of ras-induced transformation. Owing to their similarity to G proteins, regulatory elements interposed between cell-surface receptors and their effector enzymes, it has been postulated that p21, the ras oncogene protein, mediates its transforming effects by constitutive activation of proliferative signal transduction pathways. We studied the effect of ras expression on the regulation of adenylate cyclase (A.C.), key enzyme of one such major pathway. We found that ras expression correlated with a dampening of responsiveness of A.C. to several stimuli, including hormones such as isoproterenol and other agents such as GMP-PNP, forskolin and fluoride-ion. Accumulation of cAMP as measured by RIA in intact cells, as basal or in response to stimulation of A.C. activity with forskolin, was also decreased (approximately 10-fold) with ras expression. Because the regulation of calcium, another important second messenger is dependent, in part, upon cAMP and GTP-binding proteins, we investigated the possible influence of ras expression on the intracellular concentration of calcium. Steady-state intracellular free Ca2+ concentration, as measured by fluorimetry, was indeed increased by approximately 50-125% in association with ras expression. Finally, we studied the possible influence of p21ras on protein kinase C (PKC), which is a key enzyme in the important signal transduction pathway of phosphatidylinositol lipid turnover. We assessed PKC activity directly, in a cell-free system, by measuring the ability of the enzyme to transfer radiolabelled phosphate from gamma-32P-ATP to histone, and exogenous substrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute pulmonary embolism: diagnostic value of digital subtraction angiography

Digital subtraction angiography (DSA) performed via a peripheral vein was compared prospectively with selective conventional pulmonary angiography (CPA) in 54 patients suspected of having pulmonary embolism (PE). All patients also underwent ascending venography. In contrast to the conventional pulmonary angiograms, all of which were considered satisfactory, 13 of 54 digital subtraction angiograms (24%) were technically unsatisfactory. The interpretable digital subtraction angiograms had 81% sensitivity and 64% specificity. With DSA, one cannot exclude the diagnosis of PE on the basis of normal angiograms (27% false-positive results) as one can with perfusion scanning. On the other hand, DSA showed good sensitivity (94%) in medium to major PE. Therefore it may be the technique of choice in the screening of life-threatening PE for which curative emergency treatment with thrombolytic agents or embolectomy is often necessary.

New methods of quantitative assessment of the extent and significance of serial ECG changes of the repolarization phase

The authors present a method for optimally measuring variations in T wave shape and time intervals for the quantitative assessment of the significance of serial changes of the repolarization phase. The results, established on a healthy population, show the inadequacy of Bazett's formula, the constancy of maximum of T to the end of the T time interval, and good stability of the spatial T loops' morphotype. Residual intrasubject variability of corrected QT interval is mainly ascribable to physiologic, heart rate-independent changes in true onset of Q to a maximum of T time interval. The optimized mean quadratic deviation between two serial T loops is well correlated with changes in drug concentration.

Invasive nosocomial pulmonary aspergillosis: risk factors and hospital building works

A retrospective epidemiological study of 22 observations of invasive pulmonary aspergillosis, of which 18 were fatal, occurring over a period of 30 months, implicated certain building sites within the hospital. The building works were responsible for the diffusion into the atmosphere of fungal spores from normally closed reservoirs, notably false ceilings, fibrous thermal and/or acoustic insulation materials and roller-blind casings. The results of our study permit us to suggest that protective measures should be set up or that immunodepressed patients are evacuated when such works are to be carried out in an in-patient establishment.

Recurrence of pulmonary embolism during anticoagulant treatment: a prospective study

The risk of early recurrence of pulmonary embolism in patients with venous thromboembolic disease treated by anticoagulants is not well established. To determine the risk linked to contemporary proximal deep venous thrombosis, a prospective study was organised to give clinical and scintigraphic surveillance to 50 patients with angiographically proved pulmonary embolism plus phlebographically proved proximal deep vein thrombosis during the first 15 days of anticoagulant treatment. Perfusion lung scans were performed initially and on days 3, 7, and 15. Only two patients had a recurrence of pulmonary embolism during this period; both episodes were revealed by new symptoms, and one recurrence was fatal. The systematic performance of angiography in four patients found to have new scintigraphic defects led to the diagnosis of "spurious scintigraphic recurrence" in three of them. It is concluded that (a) adjusted anticoagulant treatment showed an effectiveness of 96% for preventing early recurrence of pulmonary embolism in this group of supposed high risk patients, and (b) in patients with recent pulmonary embolism new defects on systematic perfusion lung scans are not specific indicators of recurrent pulmonary embolism.

Measurement of heparin in plasma: influence of inter-subject and circadian variability in heparin sensitivity according to method

Heparin was measured, with respect to standard curves prepared with normal pooled plasma, by five methods (APTT, thrombin time, one and two stage coagulation, anti-factor Xa and chromogenic anti-factor Xa) after addition at three concentrations to plasmaprepared from normal young volunteers, hospitalized patients with malignancy and geriatric patients. By the APTT and TT, differences in sensitivity were observed at 0.4iu heparin/ml corresponding to an apparent difference in heparin level of 10 and 14 fold between high and low responding individuals. Such large differences were not apparent by anti-factor Xa assay. A circadian difference in sensitivity was also observed in the patient group such that in samples taken at night, heparin levels were 30-50% higher on average when measured in the APTT and TT. Again, such large differences were not apparent by anti-factor Xa methods. In light of recent findings about the usefulness of anti-factor Xa methods for efficient monitoring of heparin, it is suggested that this conclusion may arise from the tendency for anti-factor Xa methods to determine actual concentrations of heparin.

Longitudinal mode selection by injection in a high pressure CO(2) laser

Single longitudinal mode (SLM) selection in a 10-atm CO(2) laser is reported. Experiments have been performed with cw injection of 1 mW/cm(2) or pulsed injection of 1 mJ/cm(2) (in 50 ns) around CO(2) line centers. A simple analytical formula of the minimum intensity required for injection of a frequency nu has been obtained. It gives the dependence vs the two most important parameters: (1) the detuning nu-nu to the center nu of the net gain curve, (2) the detuning deltanu(Kappa) to the nearest longitudinal mode of the cavity. The comparison with experimental results published on TEA lasers is very successful. The application of the formula shows the possibility of SLM selection continuously tunable in a high pressure CO(2) laser with <1 mW/cm(2) if a grating is incorporated in the cavity, and with a pulsed source of 1 kW/cm(2) without any selective element. The actual sources suitable for this purpose are reviewed.