Heterogeneous phenotypes of platelet and plasma von Willebrand factor in obligatory heterozygotes for severe von Willebrand disease

To characterize the heterogeneity of severe (type III) von Willebrand disease (vWD), plasma and platelet von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor activity (Ricof) were measured in 28 obligatory heterozygotes (ie, parents or children of probands from 15 different kindreds with severe vWD). On the average, heterozygotes had low levels of vWF in both platelets and plasma. There was, however, considerable heterogeneity, with four distinct patterns. Eleven heterozygotes had concordant reduction of vWF:Ag and Ricof in both plasma and platelets; five had low levels of vWF:Ag and Ricof in plasma contrasting with normal levels in platelets; eight had a peculiar pattern, the reverse of the above (ie, low levels in platelets and normal levels in plasma); and in one, both vWF measurements were normal in plasma and platelets. These patterns were genetically determined: they were consistent in four couples of consanguineous heterozygotes and in two couples carrying the same gene deletion. Only the remaining three heterozygotes had no clearly identifiable pattern. Other findings of this study were that although most of the heterozygotes had normal bleeding times, the 7 of 28 who had prolonged bleeding times had concordantly low levels of vWF measurements in both plasma and platelets. In conclusion, this large series of obligatory heterozygotes provides evidence for phenotypic and genotypic heterogeneity of severe vWD.     

Carrier detection in hemophilia A: a cooperative international study. I. The carrier phenotype

Eight laboratories in six countries cooperated to clarify several issues concerning the phenotypes of heterozygous carriers of hemophilia "A." Plasma levels of factor VIII (F.VIII:C, formerly VIII:C) and von Willebrand factor (VWF:Ag, formerly VIIIR:Ag) of carriers and normal women were determined by various "in-house" methods; a single lyophilized plasma standard was used for all assays. Analysis of the collated data from 336 carriers (296 obligatory carriers and 40 sporadic carriers) and 137 normal women showed that there was no difference in the F.VIII:C levels of "paternal" carriers (women who had obtained the abnormal gene from their fathers) and "maternal" carriers. Neither was there a difference in the VWF:Ag levels of normal women and either type of carrier. Age was found to have a significant effect on both F.VIII:C and VWF:Ag, values being higher at very young and very old ages, the minima occurring in the 25- to 30-year range. ABO blood type had a striking effect. Women of types A, B, and AB (designated non- O in the study), both normals and carriers, had significantly higher levels of both factors than did women of type O. Analysis by laboratories showed that differences in mean levels of both factors between laboratories were highly significant. It was concluded that age, ABO blood type, and laboratory variation should be taken into account in carrier detection.     

Insulin receptors on leukemia and lymphoma cells

Tumor cells obtained from leukemia and lymphoma patients were investigated for specific insulin receptors. Using radioactive 125I- labeled insulin, specific insulin binding sites were demonstrated on most acute lymphocytic leukemia (ALL) and acute myelocytic leukemia (AML) cells, including acute promyelocytic leukemia (APL), chronic myelocytic leukemia (CML), and acute monocytic leukemia (AMoL) cells. Insulin receptors were not found on chronic lymphocytic leukemia (CLL) and malignant lymphoma (ML) cells. Specific insulin binding sites were also found on monocytes and thymocytes after treatment with phytohemagglutinin (PHA-P), but not on inactivated tonsil cells, peripheral blood lymphocytes, or thymocytes. There was no inverse correlation between the content of insulin receptors and the basal level of circulating insulin. These data suggest that the insulin receptor may be a new marker of acute leukemia and chronic myelocytic leukemia.     

Cancer‐like metabolism of the mammalian retina

The retina, like many cancers, produces energy from glycolysis even in the presence of oxygen. This phenomenon is known as aerobic glycolysis and eponymously as the Warburg effect. In recent years, the Warburg effect has become an explosive area of study within the cancer research community. The expanding knowledge about the molecular mechanisms underpinning the Warburg effect in cancer promises to provide a greater understanding of mammalian retinal metabolism and has motivated cancer researchers to target the Warburg effect as a novel treatment strategy for cancer. However, if the molecular mechanisms underlying the Warburg effect are shared by the retina and cancer, treatments targeting the Warburg effect may have serious adverse effects on retinal metabolism. Herein, we provide an updated understanding of the Warburg effect in mammalian retina.     

Management of venous thromboembolic disease in the chronically critically ill patient

Although PE is the most common preventable cause of death among U.S. hospital patients, proper treatment of thromboembolism and adequate prophylaxis in high-risk patients have been shown to be effective in saving lives. Because clinical symptoms and signs of thromboembolic disease are often nonspecific, early diagnosis and treatment rely on the capacity of physicians to adequately identify a patient at risk, choose the appropriate diagnostic modalities in a cost-effective fashion, and promptly initiate treatment. The diagnosis of VTE is particularly challenging in patients who are in the post acute period of a complex medical or surgical illness. Avenues that need to be further explored include various diagnostic tests such as spiral CT, MR imaging, and transesophageal echocardiography, which are less invasive than the present gold standard of pulmonary angiography. Also needed are better clinical data regarding the optimal choice of preventive therapy (e.g., unfragmented heparin or LMWH or mechanical devices) and clinical outcome of such therapy in patients with prolonged illness.     

Addition of sildenafil to bosentan monotherapy in pulmonary arterial hypertension.

Combination therapy has been recommended for the treatment of pulmonary arterial hypertension (PAH). However, there is scant information on combination therapy after failure of monotherapy, particularly in patients with scleroderma-associated PAH (PAH-SSD). From a group of 82 consecutive patients with PAH who received initial bosentan monotherapy, a total of 13 idiopathic PAH (IPAH) and 12 PAH-SSD patients requiring additional therapy with sildenafil were studied. Sildenafil was added for clinical deterioration based upon symptoms, New York Heart Association (NYHA) classification or 6-min walk distance (6MWD). Clinical data and haemodynamics were collected at baseline. Assessments were made at 1-3-month intervals. At baseline, there were no differences in demographics, NYHA classification, haemodynamics or 6MWD between the two groups. After initiation of bosentan, both groups experienced clinical improvement but ultimately deteriorated (median time to monotherapy failure 792 versus 458 days for IPAH and PAH-SSD patients, respectively). After addition of sildenafil, more IPAH patients tended to improve in NYHA class (five out of 13 versus two out of 12) and walked further (mean difference in 6MWD 47+/-77 m versus -7+/-40 m) compared with PAH-SSD patients. In conclusion, addition of sildenafil after bosentan monotherapy failure improved New York Heart Association class and 6-min walk distance in idiopathic pulmonary arterial hypertension patients but failed to improve either parameter in scleroderma-associated pulmonary arterial hypertension patients. Additional studies are needed to assess the tolerability and efficacy of this combination in patients with scleroderma-associated pulmonary arterial hypertension.     

von Willebrand disease "Vicenza" with larger-than-normal (supranormal) von Willebrand factor multimers

When normal volunteers or patients with type I von Willebrand disease (VWD) are given desmopressin (DDAVP), a set of larger-than-normal (supranormal) von Willebrand factor (VWF) multimers, similar to those present in VWF-containing cells such as platelets megakaryocytes and endothelial cells, appear transiently in postinfusion plasma. In two kindreds with mild lifelong bleeding symptoms transmitted as an autosomal dominant trait, all ten symptomatic members (but none of the five asymptomatic members) had a supranormal multimeric structure for plasma VWF, apparently identical to that seen for postdesmopressin normal plasma. Plasma factor VIII coagulant activity (VIII:C), VWF antigen (VWF:Ag), ristocetin-induced platelet agglutination, and ristocetin cofactor (RiCof) activity were low. Platelet VWF:Ag and RiCof levels (tested for three patients only) were normal. Bleeding times were normal or slightly prolonged. The patients' platelet multimeric structure was the same as that for normal platelets. After desmopressin infusion the plasma VWF multimeric structure remained supranormal as for preinfusion plasma, with VIII:C VWF:Ag and RiCof increasing markedly over baseline values and disappearing at a normal rate. Examination of the VWF subunit composition from three of these patients indicated that proteolytic processing of their VWF did not differ from normal. This study describes the first variant of VWD with a supranormal multimeric structure.