Refinement of lymphoma cytogenetics by the chromosome 18q21 major breakpoint region

A small (2.8-kilobase, kb) major breakpoint region localized to segment 18q21 rearranges in greater than 70% of t(14;18)(q32;q21) lymphomas. This rearrangement interrupts the Bcl-2 gene and introduces it into the Ig locus at 14q32. The rearrangement between the joining region (JH) of Ig on chromosome 14 and the 18q21 region creates a translocation- specific DNA rearrangement. We generated probes that distinguish the 14;18 juncture on the derivative (der) 14 and der (18) chromosomes, providing a molecular approach to t(14;18) identification. Approximately 60% of unselected follicular lymphomas, 20% of diffuse large cell lymphomas, and 50% of adult undifferentiated non-Burkitt lymphomas demonstrated 14;18 rearrangements within the major breakpoint region. Examination of DNA for 14;18 rearrangements resolved the identity of 14q+ chromosomes in two patient's cells that lacked an obvious reciprocal partner. Identification of the exact restriction fragments that mediate translocations complements routine cytogenetics. The detection of DNA rearrangements does not require dividing cells or the presence of an identifiable reciprocal partner and can detect clonal translocation rearrangements when the neoplastic cells are only a minority of all cells present.     

Antibodies reactive with human T cell leukemia viruses in the serum of hemophiliacs receiving factor VIII concentrate

The third member of the family of T cell leukemia viruses (HTLV III) has been proposed as the primary etiologic agent of the acquired immunodeficiency syndrome (AIDS). A high risk of AIDS has been reported among patients with hemophilia, particularly those with factor VIII deficiency who receive commercial clotting factor concentrates. In a prevalence survey conducted between September 1982 and April 1984, initial serum samples from 74% of hemophiliacs who had ever been treated with commercial factor VIII concentrate, 90% of those frequently treated with factor VIII concentrate, and 50% of those treated with both factor VIII and factor IX concentrates had antibodies reactive against antigens of HTLV III, compared with none of the hemophiliacs treated only with factor IX concentrate or volunteer donor plasma or cryoprecipitate. Two of the seropositive patients have developed AIDS-related illnesses, and a third patient died of bacterial pneumonia. One initially seronegative patient developed antibodies against HTLV III during the study and is currently well. The predominant antibody specificities appear directed against p24 and p41, the presumed core and envelope antigens of HTLV III, suggesting that factor VIII concentrate may transmit the p24 and p41 antigens of HTLV III. However, the presence of infectious retroviruses in clotting factor concentrates and the effectiveness of screening and viral neutralization procedures remain to be determined.     

Tumor necrosis factor increases the production of plasminogen activator inhibitor in human endothelial cells in vitro and in rats in vivo

The vascular endothelium plays an important role in fibrinolysis by producing tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI). The monokine tumor necrosis factor (human recombinant TNF) increased the production of PAI by cultured human endothelial cells from umbilical vein (twofold) and from foreskin microvessles (four to eight fold). This was demonstrated by titration of endothelial cell-conditioned medium with t-PA, by reverse fibrin autography, and by immunoprecipitation of [35S]PAI-1 by anti-PAI-1 IgG. TNF also induced a marked increase of PAI-1 messenger RNA (mRNA) in the cells. The stimulation of PAI activity by TNF was seen at 4 U/mL and reached a maximum at 500 U/mL. Human recombinant lymphotoxin and interleukin-1 (alpha and beta) also stimulated the production of PAI activity, while interleukin-6 was ineffective. Separate additions of TNF or interleukin-1 (IL-1) at optimal concentrations (500 U/mL and 5 U/mL, respectively) resulted in a comparable stimulation of PAI production by endothelial cells. The simultaneous addition of both mediators resulted in an additive effect. The effect of TNF could not be prevented by the addition of polymyxin B or by anti-IL-1 antibodies. Therefore, it is unlikely that TNF acts through the induction of IL-1 secretion by endothelial cells. Two hours after a bolus injection of 250,000 U/kg TNF into rats, a fivefold increase in circulating PAI levels was found. In the next ten hours, the levels returned to normal. Blood platelets do not significantly contribute to the increase in circulating PAI, because the number of platelets did not change after TNF injection and the amount of PAI in blood platelets is not sufficient for several hours during an increase in PAI activity. The acute phase reactants, fibrinogen and alpha 2-antiplasmin in rat plasma, were altered little if any two to 24 hours after injection of 250,000 U/kg TNF. In vitro, TNF did not change PAI production by human and rat hepatocytes in primary monolayer culture. Therefore, it is most likely that vascular endothelial cells contribute to the increased amount of circulating PAI induced by TNF in vivo. This increase in PAI activity might decrease fibrinolysis.     

Von Willebrand factor in the vessel wall mediates platelet adherence

A monoclonal antibody directed against the von Willebrand factor moiety (vWF) of factor VIII-von Willebrand factor (FVIII-vWF), which blocks ristocetin-induced platelet aggregation as well as the binding of FVIII- vWF to platelets in the presence of ristocetin, inhibited platelet adherence to human artery subendothelium when present in normal flowing blood. This monoclonal antibody, CLB-RAg 35, inhibited platelet adherence as a function of the shear rate. At wall shear rates below 500 s-1, platelet adherence was not affected, but at higher shear rates platelet adherence was gradually inhibited, reaching an average of 11% of the normal value at 2,500 s-1. Indirect immunofluorescence established the reactivity of CLB-RAg 35 with vWF present in artery subendothelium. Pretreatment of normal vessel walls with this antibody inhibited adherence of platelets in blood from a patient with severe homozygous von Willebrand's disease and in blood from normal individuals. The inhibition was shear-rate dependent and significant at high shear rates (2,500 s-1). By adding increasing amounts of purified FVIII-vWF to normal blood, the inhibition was gradually overcome. These data indicate that vWF present in the vessel wall contributes appreciably to platelet adherence. At high wall shear rates, platelet adherence is mediated virtually completely by both plasma FVIII-vWF and vWF in the vessel wall. At low wall shear rates (below 500 s-1), platelet adherence occurs independent of FVIII-vWF in plasma and vWF in the vessel wall.     

Association of hypocholesterolaemia with hepatitis C virus infection in HIV-infected people

Objective

To study the impact of hepatitis C virus (HCV) status on serum cholesterol levels in HIV‐infected patients.

Methods

We retrospectively analysed data from the 881 participants of the Veterans Ageing Cohort 3 Site Study. Four different models were constructed using total cholesterol, low‐density lipid (LDL) cholesterol, high‐density lipid (HDL) cholesterol and triglycerides as dependent variables. The relevant covariates included HCV antibody status, HIV medication class, CD4 count, HIV viral load, glucose level, lipid‐lowering drug use, gender, race, age, liver function test results, ethanol use, drug use, and HIV exposure category. Variables excluded from the final model included niacin use, gender, race, age, current ethanol use, and HIV exposure category.

Results

Of the 881 HIV‐positive patients enrolled in the study, 700 (79%) were screened for HCV antibody, with 300 (42.8%) HCV antibody positive and 400 (57.2%) HCV antibody negative. A positive HCV antibody status was independently associated with lower total cholesterol levels (P=0.001) and LDL cholesterol levels (P<0.001) but not with lower HDL cholesterol or triglyceride levels. HCV‐positive patients had predicted LDL levels 19 mg/dL lower than those of HCV‐negative subjects. HCV infection was also associated with a decreased use of lipid‐lowering medication, and protease inhibitor use was associated with increased LDL and total cholesterol levels.

Conclusions

HCV infection has been associated with lower cholesterol levels in HIV‐negative individuals, and the same appears to be true with HIV‐infected patients. This is an interesting finding given that HCV particles bind to LDL receptors in vitro and also because HCV–lipid interactions appear to be important in the HCV replication cycle.

     

Delta glycophorin (glycophorin B) gene deletion in two individuals homozygous for the S--s--U-- blood group phenotype

Blood cells from two unrelated individuals whose erythrocytes exhibit respectively N S-s-U- and MN S-s-U- blood group phenotypes were examined by immunoblotting, periodic acid-Schiff (PAS) staining, and Southern blotting. Protein bands characteristic of delta glycophorin (glycophorin B) were absent from the immunoblots of whole erythrocyte lysates when probed with polyclonal glycophorin antisera and from isolated erythrocyte membranes stained with PAS reagents. Genomic DNA from the two individuals' leukocytes was digested with a panel of restriction enzymes and probed with alpha M glycophorin cDNA obtained from human K562 leukemic cell line. The EcoRI, PstI, and KpnI restriction site patterns were identical to those of S+s+U+ controls in fragment numbers and relative size but differed from controls in band intensities. Restriction mapping with HindIII, PvuII, SacI, MspI, and BamHI revealed that S-s-U- individuals lack fragments that are reproducibly observed in S+s+U+ controls, and most likely encode delta glycophorin. Using truncated 5' and 3' cDNA segments as probes and comparing, in control individuals, hybridization intensities of fragments with amino acid sequence homologies, we have inferred the assignment of restriction fragments to the alpha and delta glycophorin genes. Our results suggest that the absence of delta glycophorin in the two S-s-U- individuals is a result of deletion of the entire delta glycophorin gene. This is the first report of a glycophorin gene deletion.     

Human blood monocytes and platelets share a cell surface component

We describe a surface determinant shared by human monocytes and cells of the megakaryocytic axis that has been identified using a mouse monoclonal antibody. This monocyte-platelet antigen (MPA) is expressed on all (greater than 99%) of peripheral blood monocytes, platelets, and megakaryocytes. It is also expressed weakly on the monocytic cell line U937 and the promyelocytic line HL60 and is present on cells from 3 of 4 AML patients examined. It is absent from polymorphonuclear leukocytes, T and B lymphocytes, erythrocytes, and a panel of hematopoietic cell lines. MPA is stripped from monocyte membranes with pronase and is reexpressed overnight. The determinant is carried on a noncovalently linked biomolecular complex with molecular weights of 93,000 and 135,000.     

High-molecular weight kininogen is present in cultured human endothelial cells: localization, isolation, and characterization

The presence of high-molecular weight (mol wt) kininogen was demonstrated in cultured human endothelial cells derived from the umbilical cord by immunofluorescence techniques. Cultured human endothelial cells contain 58 +/- 11 ng (n = 16) high-mol wt kininogen/10(6) cells as determined by an enzyme-linked immunosorbent assay (ELISA) specific for high-mol wt kininogen. High-mol wt kininogen was isolated from cultured human endothelial cells by immunoaffinity chromatography. Nonreduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that endothelial cell high-mol wt kininogen consisted of five protein bands with mol wts of 95,000, 85,000, 65,000, 46,000, and 30,000 daltons. Immunoblotting of the endothelial cell high-mol wt kininogen by using specific antisera against the heavy and light chain indicated that the 95,000-, 85,000-, and 65,000-dalton bands consisted of the heavy and light chain whereas the 46,000- and 30,000-dalton bands reacted only with the anti-light chain antiserum. Immunoprecipitation studies performed with lysed, metabolically labeled endothelial cells and monospecific antisera directed against high-mol wt kininogen suggested that high-mol wt kininogen is not synthesized by the endothelial cells. Endothelial cells cultured in high-mol wt kininogen-free medium did not contain high-mol wt kininogen. These studies indicate that endothelial cell high-mol wt kininogen was proteolytically cleaved in the culture medium and subsequently internalized by the endothelial cells. Binding and internalization studies performed with 125I-labeled, proteolytically cleaved, high-mol wt kininogen showed that endothelial cells can indeed bind and internalize proteolytically cleaved high-mol wt kininogen in a specific and saturable way.     

Midfacial growth and dental arch relationships in bilateral cleft palate following secondary alveolar bone grafting and orthodontic intervention: Factors predicting a Le Fort I osteotomy at age 18

Objective

To evaluate midfacial growth and dental arch relationships in patients treated for bilateral cleft lip and palate (BCLP).