Life-threatening reaction to factor VIII concentrate in a patient with severe von Willebrand disease and alloantibodies to von Willebrand factor

A 16-yr-old girl with severe von Willebrand disease complicated by the development of precipitating alloantibodies to von Willebrand factor (anti-VWF) had a life-threatening anaphylactoid reaction immediately after the infusion of a commercial plasma concentrate of factor VIII/von Willebrand factor. An early post-infusion activation of the complement system was demonstrated by the appearance of C3 split products and by the drop of serum CH50 activity, occurring in parallel with a post-infusion drop in the anti-VWF antibody levels. Immune complexes remained unchanged in the early post-infusion period and rose to a moderate extent only after 24 h. We conclude that biologically active products of the complement system contributed to the onset of this life-threatening reaction which occurred after concentrate infusion.

Correction of the bleeding time in treated patients with severe von Willebrand disease is not solely dependent on the normal multimeric structure of plasma von Willebrand factor

Even though it is generally held that cryoprecipitate and fraction I-O correct the prolonged bleeding time (BT) in patients with von Willebrand disease (VWD), perusal of reported data indicates that the correction is usually short-lasting and often partial. We decided to do a controlled study of the relationship between the multimeric structure of von Willebrand factor (VWF) and the BT in five patients with severe (type III) VWD after infusion of three plasma concentrates ("wet" cryoprecipitate, lyophilized cryoprecipitate, and fraction I-O) given in random order. The dosage of concentrates was tailored from in vitro measurements to achieve post-infusion levels of ristocetin cofactor above the lower normal limit (50 U/dL) for at least 3 hours. The postinfusion BT became transiently normal in only two of five patients treated with wet cryoprecipitate, whereas it remained prolonged in all five patients treated with lyophilized cryoprecipitate or fraction I-O. For all the concentrates, the proportion of large VWF multimers calculated by scanning the electrophoretic gels were the same as those for normal standard plasmas. An intact multimeric structure was recovered in postinfusion plasmas of patients treated with wet cryoprecipitate, whereas there was a postinfusion loss of large multimers after lyophilized cryoprecipitate and fraction I-O. These findings indicate that the attainment of a normal BT is the exception rather than the rule after the infusion of three plasma fractions used in the treatment of severe VWD, and that an intact multimeric structure in concentrates and postinfusion plasmas is necessary but not sufficient to sustain a normal BT.

Primitive neuroectodermal tumor presenting as a delayed sequela to cranial irradiation and intrathecal methotrexate

A patient developed a primitive neuroectodermal tumor (PNET) many years after therapeutic cerebral radiation and methotrexate treatment for leukemia. The differential radiologic and histologic diagnoses, as well as the possible co-oncogenic effects of radiation and methotrexate, are evaluated.

Vasopressin analogues. Their role in disorders of hemostasis

At this time, when the acquired immunodeficiency syndrome, hepatitis, and other blood-borne diseases threaten patients, with bleeding disorders, who need treatment with blood products, it is rewarding to realize that a number of them can be safely and effectively treated through the stimulation of their own VIII:C and vWF production with desmopressin. Desmopressin is clinically useful for treatment of patients with moderate and mild hemophilia. The limits of the clinical indications are the nature of the bleeding episode, the resting factor level, the level that must be achieved, and the length of time the level must be maintained to manage any given bleeding episode. Desmopressin can be used more extensively to raise VIII:C in von Willebrand's disease, than in classic hemophilia, because fewer of the patients have the severe form of the disease that is unresponsive to desmopressin. VIII:C increases to about four times the resting values that can be expected in both hemophilia and von Willebrand's disease, but it must be kept in mind that the range of individual responses is large. Even though it is not easy to correct the prolonged bleeding time, particularly in patients with dysfunctional vWF, this drawback is of clinical importance for only a minority of cases. Use of desmopressin in acquired diseases of primary hemostasis has been proposed more recently, and our experience is more limited than for congenital bleeding disorders. Uremia is probably the most firmly established indication, because the bleeding time is often dramatically shortened by desmopressin, and hemorrhages can be stopped or prevented. The indications for the compound in liver cirrhosis and congenital and acquired platelet dysfunctions are promising but much less well-established. The mechanism of action of desmopressin is not well-known, and more work must be done to fill this important gap. This problem is not only of theoretical importance, because understanding of the mechanism of action of the compound should open up new perspectives into understanding the physiological mechanisms that regulate hemostasis. Many unclarified aspects of the mechanism of desmopressin action might be elucidated by using specific antagonists and also by using appropriate animal models. (Dogs and primates respond partially to desmopressin, but rats and rabbits do not respond at all).(ABSTRACT TRUNCATED AT 400 WORDS)

Serum uric acid is not independently associated with plasma renin activity and plasma aldosterone in hypertensive adults

BACKGROUND AND AIMS

In experimental investigations conducted in rats, raising serum uric acid (SUA) levels resulted in the stimulation of intrarenal renin expression. Studies in humans exploring the association of SUA with plasma renin activity (PRA) yielded conflicting results. Moreover, little is known about the relationship of SUA with plasma aldosterone concentration (PAC). The study aimed to assess the relationship between SUA levels, PRA, and PAC and the influence of age, gender, body mass index (BMI), and hyperuricemia on these relationships in subjects with essential hypertension (EH).

METHODS AND RESULTS

We enrolled 372 hypertensive patients (mean age 45 ± 12 years, men 67%) with uncomplicated EH that was not pharmacologically treated. The study population was divided in tertiles according to SUA levels. While PRA did not differ significantly across the three tertiles, PAC was higher in subjects belonging to the uppermost tertile of SUA than those in the lower ones (p = 0.0429); however, this difference lost statistical significance after adjustment for age, sex, BMI, and serum creatinine. Univariate correlation analyses showed significant associations of SUA with PRA (r = 0.137; p = 0.008) and PAC (r = 0.179; p < 0.001). However, these relationships were not significant after correcting for confounding factors in multiple linear regression analyses. We did not observe statistically significant effect modification by gender, age, BMI, and hyperuricemia.

CONCLUSION

SUA levels are weakly associated with PRA and PAC in adults with untreated EH. These relationships were lost after adjustment for age, sex, BMI, and serum creatinine.

Cannabinoid receptor agonist attenuates angiotensin II-induced enlargement and mitochondrial dysfunction in rat atrial cardiomyocytes

Pathological remodeling of atrial tissue renders the atria more prone to arrhythmia upon arrival of electrical triggers. Activation of the renin-angiotensin system is an important factor that contributes to atrial remodeling, which may result in atrial hypertrophy and prolongation of P-wave duration. In addition, atrial cardiomyocytes are electrically coupled via gap junctions, and electrical remodeling of connexins may result in dysfunction of coordinated wave propagation within the atria. Currently, there is a lack of effective therapeutic strategies that target atrial remodeling. We previously proposed that cannabinoid receptors (CBR) may have cardioprotective qualities. CB13 is a dual cannabinoid receptor agonist that activates AMPK signaling in ventricular cardiomyocytes. We reported that CB13 attenuates tachypacing-induced shortening of atrial refractoriness and inhibition of AMPK signaling in the rat atria. Here, we evaluated the effects of CB13 on neonatal atrial rat cardiomyocytes (NRAM) stimulated by angiotensin II (AngII) in terms of atrial myocyte enlargement and mitochondrial function. CB13 inhibited AngII-induced enhancement of atrial myocyte surface area in an AMPK-dependent manner. CB13 also inhibited mitochondrial membrane potential deterioration in the same context. However, AngII and CB13 did not affect mitochondrial permeability transition pore opening. We further demonstrate that CB13 increased Cx43 compared to AngII-treated neonatal rat atrial myocytes. Overall, our results support the notion that CBR activation promotes atrial AMPK activation, and prevents myocyte enlargement (an indicator that suggests pathological hypertrophy), mitochondrial depolarization and Cx43 destabilization. Therefore, peripheral CBR activation should be further tested as a novel treatment strategy in the context of atrial remodeling.

Evaluation of the nature of mildly prolonged prothrombin times

Twenty-one asymptomatic individuals with a mildly prolonged prothrombin time (greater than 2 SD from the prothrombin time of the reference plasma) were found to have a mild isolated factor VII (F VII) defect (mean 38.8 U/dl; SD 13.2). Factor VII antigen levels were also found to be reduced (mean 45.5 U/dl; SD 7.8) in 13 of them. These figures were compared with those of 50 normals and 28 obligatory heterozygotes for F VII deficiency. The phenotypical behaviors in the propositi were found to be equal to those of the F VII congenital deficiency heterozygotes: the discrepant one (VII+) and the nondiscrepant one (VII-/R). Fifteen families of the propositi could also be studied, totalling 55 additional individuals; in 25 of them (ten pedigrees) a mild F VII deficiency was found showing the same phenotypical features of the corresponding propositi. We therefore believe that these individuals with mild F VII deficiency can be considered as heterozygotes for the defect, since the other vitamin K-dependent clotting factors were normal; the defect is transmitted throughout the kindred with the same mode of inheritance as F VII congenital deficiency; and F VII:C and F VII:Ag levels are highly comparable with those of known obligatory heterozygotes for F VII deficiency. On the grounds of a careful statistical analysis we propose a formula which allows a discrimination between the two phenotypes of the heterozygotes for F VII congenital deficiency. In addition it is suggested that sensitive tissue thromboplastins should be used to pick up these mild defects.

On the relationship among linear type traits and functional longevity in the Italian Mediterranean buffalo using a Weibull proportional hazards model

The Weibull proportional hazards model was used to identify the nongenetic effects that affect length of productive life (LPL) of the Italian Mediterranean buffalo. Data were provided by the Italian National Association of Buffalo Breeders and included records of reproductive, productive, and linear type traits from 59,943 buffalo with first calving from 2002 to 2019. Data were divided into 4 geographical regions to determine whether the relationship between the investigated effects and LPL varied by region. Length of productive life was defined as the number of days from the first calving to culling for those buffaloes that were culled (uncensored) or to the date of the last test-day for those that are still alive (censored). The Weibull model included time-dependent effects of herd-year-season of calving, parity and stage of lactation, production as within-herd deviations, as well as time-independent effects of age at first calving, year of birth, type of reproduction (natural mating vs. AI), classifier, and ten linear type traits. The average duration of productive life was 1,604 days. Both year of birth and production level had a significant effect on culling risk. Moreover, culling risk decreased linearly across parities. The reference point for age at first calving relative to other classes was set at 35 months. A significant relationship between linear type traits and relative culling risk was also observed, being highest for buffaloes with the lowest linear scores. The results show that the Weibull model provides consistent and robust risk estimates. Therefore, this model would be recommended for future implementation of the first genetic evaluation of LPL in the Italian Mediterranean buffalo.

Human T cell activation. Synergy between CD73 (ecto-5'-nucleotidase) and signals delivered through CD3 and CD2 molecules

Interaction of the glycosyl phosphatidylinositol-linked differentiation Ag CD73 (ecto-5'-nucleotidase) with the CD73-specific mAb 1E9 generates agonistic signals that strongly synergize with T cell activation induced by CD3 and CD2 mAb. This synergy is observed only when 1E9 is immobilized on plastic and occurs in the absence of accessory cells or exogenous lymphokines. 1E9 induces a rapid (though transient) increase in [Ca2+]i in a minor proportion (20 to 30%) of unfractionated T lymphocytes (presumably CD73+ cells). However, this [Ca2+]i mobilization is not sufficient to fully activate CD73+ T cells, as shown by the requirement of additional signals such as CD3 or CD2 stimulation to initiate T cell proliferation. These signals cannot be substituted by the exogenous lymphokines, rIL-1, rIL-2, or rIL-4, or PMA (when T cells are rigorously depleted of monocytes). These data indicate that CD73 may behave as an accessory molecule regulating interactions between T cells and antigens or APC. A comparison was carried out with mAb 9.3 to the differentiation Ag CD28, another agonistic molecule with activating properties similar to CD73. Despite their lower percentage, the ability of CD73+ T cells to amplify the proliferation induced by CD3 or CD2 mAb was equivalent or even greater than that of CD28+ T cells. Once activated, CD73+ cells may recruit the remaining (CD73-) cells primed by CD3 or CD2 stimulation. Based on these data, we suggest that CD73+ T lymphocytes may be a specialized subset to amplify immune responses originated by the CD3 and CD2 activation pathways. Finally, the functional association between CD73 and integral membrane molecules like CD3 and CD2 suggests that GPI-anchored molecules may play a role in transmembrane signaling mediated by conventional second messenger systems.

Identification of a thrombin receptor with factor Xa receptor and tissue factor in human pancreatic carcinoma cells

Venous thromboembolism is a common feature of pancreatic cancer. The underlying mechanism is unclear, but is likely to involve thrombin generation on the cell surface. Human pancreatic carcinoma cell lines (n=8) have been studied immmunohistochemically for the expression of tissue factor, factor Xa receptor, and thrombin receptor. Each antigen had a distinct pattern of immunoreactivity in cell membrane and cytoplasm. Tissue factor was predominantly localised to the membrane, whereas thrombin and factor Xa receptor were largely cytoplasmic in distribution. The results support the hypothesis of a coagulation cascade that starts with tissue factor, leads to thrombin generation, and might confer a biological advantage on tumour cells.

Human T cell activation. Synergy between CD73 (ecto-5'-nucleotidase) and signals delivered through CD3 and CD2 molecules

Interaction of the glycosyl phosphatidylinositol-linked differentiation Ag CD73 (ecto-5'-nucleotidase) with the CD73-specific mAb 1E9 generates agonistic signals that strongly synergize with T cell activation induced by CD3 and CD2 mAb. This synergy is observed only when 1E9 is immobilized on plastic and occurs in the absence of accessory cells or exogenous lymphokines. 1E9 induces a rapid (though transient) increase in [Ca2+]i in a minor proportion (20 to 30%) of unfractionated T lymphocytes (presumably CD73+ cells). However, this [Ca2+]i mobilization is not sufficient to fully activate CD73+ T cells, as shown by the requirement of additional signals such as CD3 or CD2 stimulation to initiate T cell proliferation. These signals cannot be substituted by the exogenous lymphokines, rIL-1, rIL-2, or rIL-4, or PMA (when T cells are rigorously depleted of monocytes). These data indicate that CD73 may behave as an accessory molecule regulating interactions between T cells and antigens or APC. A comparison was carried out with mAb 9.3 to the differentiation Ag CD28, another agonistic molecule with activating properties similar to CD73. Despite their lower percentage, the ability of CD73+ T cells to amplify the proliferation induced by CD3 or CD2 mAb was equivalent or even greater than that of CD28+ T cells. Once activated, CD73+ cells may recruit the remaining (CD73-) cells primed by CD3 or CD2 stimulation. Based on these data, we suggest that CD73+ T lymphocytes may be a specialized subset to amplify immune responses originated by the CD3 and CD2 activation pathways. Finally, the functional association between CD73 and integral membrane molecules like CD3 and CD2 suggests that GPI-anchored molecules may play a role in transmembrane signaling mediated by conventional second messenger systems.