Gene Literature Dashboard

We have studied the formation of covalent complexes between 125I-urokinase (125I-UK) and proteins in human plasma. Although 125I-UK reacts with many proteinase inhibitors in purified systems, the predominant complexes formed in plasma are with antithrombin III (ATIII) and alpha 2-macroglobulin (alpha 2M). 125I-UK interacts with purified alpha 2M or alpha 2M in plasma to form a characteristic pattern of multiple complexes whose Mr values by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis are in the range of 380 000-720 000, under non-reducing conditions, and 180 000-430 000 after reduction. We also examined the inhibition of UK amidolytic activity by plasma and by purified ATIII. In the presence of saturating concentrations of ATIII and heparin, an apparent first-order rate constant of 6.8 X 10(-1) s-1 was calculated for the inhibition of urokinase. In contrast, the rate constant for the formation of covalent ATIII-UK complexes was lower, suggesting the inhibition of UK proceeds first via the formation of transient non-covalent intermediates that are then transformed more slowly into covalent end products. The observed rate constants for enzyme inhibition or complex-formation with plasma or purified inhibitors are insufficient to account for the reported clearance rate of injected UK in vivo.

Previous studies have shown that the peptides obtained from accessory cell and B-cell Ia molecules are identical but that the alpha chains of B-cell Ia molecules are more extensively sialylated than those of accessory cells. The present studies were designed to determine whether this glycosylation difference can account for the functional difference in the capacity of the two cell types to activate alloreactive T cells. The experimental data show that normal resting B cells lack the capacity to induce DNA synthesis or differentiation in alloreactive T cells. T cells do recognize polymorphisms in B-cell Ia molecules, however, because they can be specifically primed for a subsequent proliferative stimulus of the same haplotype. The mitogenic signal for T cells is delivered by either allogeneic accessory cells or neuraminidase-treated B cells. Therefore, the T-cell receptor(s) may contain a site specific for the nonpolymorphic asialocarbohydrate moiety on the alpha chains of accessory cell Ia molecules.

Slow ionic currents were measured in the rat omohyoid muscle with the three-microelectrode voltage-clamp technique. Sodium and delayed rectifier potassium currents were blocked pharmacologically. Under these conditions, depolarizing test pulses elicited an early outward current, followed by a transient slow inward current, followed in turn by a late outward current. The early outward current appeared to be a residual delayed rectifier current. The slow inward current was identified as a calcium current on the basis that (a) its magnitude depended on extracellular calcium concentration, (b) it was blocked by the addition of the divalent cations cadmium or nickel, and reduced in magnitude by the addition of manganese or cobalt, and (c) barium was able to replace calcium as an inward current carrier. The threshold potential for inward calcium current was around -20 mV in 10mM extracellular calcium and about -35 mV in 2 mM calcium. Currents were net inward over part of their time course for potentials up to at least +30 mV. At temperatures of 20-26 degrees C, the peak inward current (at approximately 0 mV) was 139 +/- 14 microA/cm2 (mean +/- SD), increasing to 226 +/- 28 microA/cm2 at temperatures of 27-37 degrees C. The late outward current exhibited considerable fiber-to-fiber variability. In some fibers it was primarily a time-independent, nonlinear leakage current. In other fibers it was primarily a time-independent, nonlinear leakage current. In other fibers it appeared to be the sum of both leak and a slowly activated outward current. The rate of activation of inward calcium current was strongly temperature dependent. For example, in a representative fiber, the time-to-peak inward current for a +10-mV test pulse decreased from approximately 250 ms at 20 degrees C to 100 ms at 30 degrees C. At 37 degrees C, the time-to-peak current was typically approximately 25 ms. The earliest phase of activation was difficult to quantify because the ionic current was partially obscured by nonlinear charge movement. Nonetheless, at physiological temperatures, the rate of calcium channel activation in rat skeletal muscle is about five times faster than activation of calcium channels in frog muscle. This pathway may be an important source of calcium entry in mammalian muscle.

Severe congestive cardiac failure developed in a few weeks in a 44 year old man who had undergone porto-caval anastamosis for post-hepatitis cirrhosis one year previously and then treated for anaemia by repeated blood transfusion and chronic daily oral iron therapy. Infiltrative, congestive and restrictive cardiomyopathy was diagnosed in the presence of global cardiomegaly, electrocardiographic changes (microvoltage, diffuse ST-T wave changes), echocardiographic appearances (dilatation of the left ventricle, with hypertrophic and hypokinetic walls), and hemodynamic signs of adiastole with equalisation of filling pressures at 15 mmHg and a cardiac index of 1,88 l/min/m2. Cardiac haemochromatosis was confirmed by the laboratory (serum iron: 35 mumol/l; siderophilin saturation: 100 p. 100; serum ferritin: 1854 ng/ml; induced siderouria: 51 mg/24 hours) and histological findings (endomyocardial biopsy showing pigment overload). The absence of a family history, of homozygote A3 antigen, of diabetes, of iron overload on hepatic biopsy one year previously, excluded the diagnosis of familial idiopathic haemochromatosis. A secondary form of the disease was diagnosed on a possible genetic predisposition (heterozygote A3 antigen) and on environmental factors (blood transfusions, iron therapy, cirrhosis, alcoholism and perhaps the porto-caval anastamosis. Cardiac haemochromatosis was cured in this case by iron chelating therapy comprising daily subcutaneous infusions of 2 g of desferrioxamine for 2 months. The cure was confirmed by regression of the signs of clinical cardiac failure and of cardiomegaly, the increase in QRS voltages and the near normalisation of the hemodynamic and laboratory findings.

The thyroid function of 49 patients homozygous for the hemochromatosis allele was studied by measurement of serum thyroxine and thyrotropin concentrations. Of 34 homozygous men, three were found to be hypothyroid (thyroxine, less than 3.0 micrograms/dL and thyrotropin, greater than 40 ImU/mL) and one was hyperthyroid (thyroxine, 24 micrograms/dL). All 15 homozygous women had normal thyroid function. The hypothyroid patients had elevated titers of antithyroid antibodies. Histologic examination of the thyroid at autopsy of one hypothyroid patient showed notable iron accumulation and fibrosis with modest lymphocytic infiltration. The causative importance of iron deposition in thyroid diseases associated with hemochromatosis was suggested by the reversal of the usual sex ratio of thyroid dysfunction. Men with hemochromatosis had a much greater iron load than women, and they also had a surprisingly higher incidence of thyroid disease. Iron may have caused injury to the thyroid, followed by the development of antithyroid antibodies and hypothyroidism. The frequency of thyroid disorders in men with hemochromatosis is about 80 times that of men in the general population.

The oestradiol (RE) and progesterone (RP) receptor levels were analyzed in 26 tumour fragments (200-500 mg) from breast cancer patients. After pulverization of tissue, one part was analyzed by the routine dextran-coated charcoal (DCC) method and the other by a micromethod as follows: (i) cytosol incubation using the DCC method but in the simultaneous presence of [3H]oestradiol and [3H]R5020 (ii) extraction of the steroids bound to the receptor by precipitation with ethanol/TCA (iii) high pressure liquid chromatography (HPLC) on a modular system, with a C185 microns column and an elution by gradient mixture methanol/water. The fractions were collected and the radioactivity counted. The separation of oestradiol from R 5020 was rapid and complete. In addition dexamethasone was separated by this system making possible triple measures of RE, RP and glucocorticoid receptors. A highly significant correlation was obtained between the 2 methods: RE = 0.996, P less than 0.001; RP r = 0.975, P less than 0.001, implying that the thresholds of positivity, i.e. for therapeutic decisions, remain unchanged. Simultaneous measurement of RE and RP in a single needle biopsy is possible with this micromethod.

<h4>Unlabelled</h4>In an investigation on 19 patients with traumatic (n = 11) and septic (n = 8) shock, at risk of developing adult respiratory distress syndrome (ARDS), various coagulation and fibrinolysis variables and also blood gases and chest x-ray were monitored. Eight patients developed ARDS - two after traumatic shock and six following septic shock.<h4>Laboratory findings</h4>the conventional disseminated intravascular coagulation variables (fibrinogen, platelet counts, activated partial thromboplastin time, ethanol gelation test, thrombotest, normotest and fibrin degradation products) could not discriminate between ARDS and non-ARDS patients, but showed an essentially similar reaction pattern in these two groups. Antithrombin-III and plasminogen levels were significantly lower in patients with ARDS, while factor VIII-related antigen levels were significantly higher in ARDS than in non-ARDS patients.<h4>Clinical data</h4>patients with septic shock run a significantly greater risk of developing ARDS (6 of 8) than those with traumatic shock (2 of 11; P less than 0.02). Furthermore, the onset of ARDS after septic shock seems to occur in a more rapid way, while ARDS following traumatic shock develops more gradually. Early ventilator treatment with positive end expiratory pressure counteracts the classical radiographic picture of ARDS with bilateral alveolar densities.

Plasma heparin and ATIII levels were determined using recently developed fluorometric substrate techniques on serial samples taken from 9 unselected patients undergoing open-heart surgery on cardiopulmonary bypass. The fluorometric assay for ATIII and established clotting and immunological methods showed a highly significant correlation (p less than 0.001). Heparin recovery was reduced in all cases, and plasma levels (fluorometric assay) demonstrated poor correlation to Whole Blood Activated Clotting Time (Hemochron) estimations. ATIII levels were dramatically reduced during bypass, and in 3 cases reached levels below 0.08 iu/ml. Heparin reversal schedules based upon empirical dosage led to excessive protamine administration by a mean factor of 3.3, as assessed by in vitro neutralization of standardized heparin concentrations.