Identification and characterization of insulin-like growth factor receptors on adult rat cardiac myocytes: linkage to inositol 1,4,5-trisphosphate formation.

Cultured cardiac myocytes from adult Sprague-Dawley rats express both insulin-like growth factor-I (IGF-I) receptors and insulin-like growth factor-II/mannose 6-phosphate (IGF-II/Man6P) receptors and respond to IGF-I with a dose-dependent accumulation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and inositol 1,4-bisphosphate [Ins(1,4)P2]. Specific binding of [125I]IGF-I to isolated membranes from cultured cardiac myocytes amounted to 1-1.2%. Binding of [125I]IGF-I was inhibited by unlabeled IGF-I at nanomolar concentrations and insulin at much higher concentrations. These data suggest that IGF-I binds to its own receptor on rat cardiac myocytes. Competitive binding studies using isolated membranes from cardiac myocytes and [125I]IGF-II showed 2-4% specific binding. Binding of [125I]IGF-II was inhibited by IGF-II and much less potently by IGF-I and insulin. Immunoglobulin G (IgG) 3637 (an IgG directed against the IGF-II/Man6P receptor) partially inhibited binding of [125I]IGF-II whereas nonimmune IgG did not. Affinity cross-linking studies with [125I]IGF-II and cardiac myocyte membranes and subsequent analysis of the ligand-receptor complex using SDS-PAGE and autoradiography showed a radiolabeled band of approximately 250 kilodalton (kDa). The formation of the [125I]IGF-II-receptor complex was inhibited by incubation with IGF-II and IgG 3637 but not by insulin or nonimmune IgG. Western blotting of protein extracts from cultured cardiac myocytes was performed using IgG 3637 and an immunoperoxidase technique for the visualization of the IGF-II/Man6P receptor protein. A specific band at 220 kDa under nonreducing conditions was detected on the blots, providing further evidence for the expression of the IGF-II/Man6P receptor by cardiac myocytes. The effect of IGFs on the accumulation of inositol phosphates was measured by HPLC analysis of perchloric acid extracts from myo-[3H]inositol-labeled cultured cardiac myocytes. IGF-I (50 ng/ml) stimulated the accumulation both of Ins(1,4,5)P3 and Ins(1,4)P2 after 30 sec by 43% and 63%. IGF-II (up to 500 ng/ml) had no significant effect on inositol phosphate accumulation under the same conditions. However, in the presence of millimolar concentrations of Man6P, IGF-II (500 ng/ml) also increased Ins(1,4,5)P3 accumulation by 59%. We conclude that cardiac myocytes from adult rats express IGF receptors and respond to IGFs with the accumulation of Ins(1,4,5)P3 and Ins(1,4)P2. This effect seems to be mediated by an IGF-I receptor-specific pathway.     

Treatment of metastatic renal cancer with capsid-modified oncolytic adenoviruses

Renal cancer is a common and deadly disease that lacks curative treatments when metastatic. Here, we have used oncolytic adenoviruses, a promising developmental approach whose safety has recently been validated in clinical trials. Although preliminary clinical efficacy data exist for selected tumor types, potency has generally been less than impressive. One important reason may be that expression of the primary receptor, coxsackie-adenovirus receptor, is often low on many or most advanced tumors, although not evaluated in detail with renal cancer. Here, we tested if fluorescence-assisted cell sorting could be used to predict efficacy of a panel of infectivity-enhanced capsid-modified marker gene expressing adenoviruses in renal cancer cell lines, clinical specimens, and subcutaneous and orthotopic murine models of peritoneally metastatic renal cell cancer. The respective selectively oncolytic adenoviruses were tested for killing of tumor cells in these models, and biodistribution after locoregional delivery was evaluated. In vivo replication was analyzed with noninvasive imaging. Ad5/3-Delta24, Ad5-Delta24RGD, and Ad5.pK7-Delta24 significantly increased survival of mice compared with mock or wild-type virus and 50% of Ad5/3-Delta24 treated mice were alive at 320 days. Because renal tumors are often highly vascularized, we investigated if results could be further improved by adding bevacizumab, a humanized antivascular endothelial growth factor antibody. The combination was well tolerated but did not improve survival, suggesting that the agents may be best used in sequence instead of together. These results set the stage for clinical testing of oncolytic adenoviruses for treatment of metastatic renal cancer currently lacking other treatment options.     

Oncolytic vaccinia virus for the treatment of cancer

INTRODUCTION: Gene therapy offers promising approaches for the development of anticancer agents with new modes of action. Among gene therapy vectors, vaccinia virus has emerged as an attractive agent especially when used as an oncolytic virus. AREAS COVERED: This review describes the use of vaccinia virus in cancer therapy as a gene therapy vector, as an oncolytic virus and in the generation of oncolysates. The main achievements of each field are summarized with a special emphasis on vaccinia as an oncolytic vector and its combination therapies. The virus that has advanced furthest in clinical trials, GM-CSF expressing JX-594, is described in detail and its preclinical and clinical data are reviewed. EXPERT OPINION: Vaccinia virus has great potential in cancer gene therapy, especially when used as an oncolytic virus. In particular, JX-594 has shown promising preclinical and clinical data, and a multi-continental randomized Phase III trial in hepatocellular carcinoma is expected to start soon.     

Use of fecal occult blood test in hospitalized patients: Survey of physicians practicing in a large central Canadian health region and Canadian gastroenterologists

BACKGROUND:

Although the fecal occult blood test (FOBT) was developed for colorectal cancer screening in the outpatient setting, it continues to be used among hospitalized patients. No previous study has evaluated the knowledge, beliefs and attitudes of practicing physicians on the use of FOBT among hospitalized patients and compared practices among physicians with different medical specialty training.

OBJECTIVE:

To survey physicians in the Winnipeg Regional Health Authority (WRHA) and Canadian gastroenterologists (GIs) on the use of FOBT in hospitals.

METHODS:

A survey was distributed by e-mail to internists (n=198), emergency medicine (EM) physicians (n=118), general surgeons (n=47) and family medicine (FM) physicians with admitting privileges (n=29) in the WRHA. Canadian GIs were surveyed through the membership database of the Canadian Association of Gastroenterology (CAG) (n=449). The survey included items regarding demographics of the respondents and their current use of FOBT in hospitals.

RESULTS:

Response rates ranged from 18% among CAG members to 69% among FM physicians in the WRHA. General internal medicine, general surgeon and GI respondents were less likely to order a FOBT and less likely to believe that an FOBT was useful in assessing emergency room or hospitalized patients when compared with FM and EM respondents (P<0.001). The most common indications for ordering a FOBT were black stools and anemia with and without iron deficiency. Two-thirds of EM physicians preferred point-of-care testing rather than laboratory reporting of FOBT.

CONCLUSIONS:

The present survey suggests that FOBTs are commonly used in hospitals by EM and FM physicians for indications such as anemia and black stools.     

The place of high-dose BEAM therapy and autologous bone marrow transplantation in poor-risk Hodgkin's disease. A single-center eight- year study of 155 patients

Although high-dose chemotherapy and autologous bone marrow transplantation (ABMT) are increasingly being used for the treatment of relapsed and resistant Hodgkin's disease, there have been few large, single-center studies reported with adequate follow-up to allow full evaluation of this therapeutic modality. We present 155 poor-risk Hodgkin's disease patients who received high-dose BEAM (BCNU, etoposide, cytosine arabinoside, and melphalan) chemotherapy and ABMT who have been studied over a period of 8 years. All patients had either not attained a remission on mechlorethamine, vincristine, procarbazine, prednisone-type therapy and had poor prognostic features at presentation, not attained a complete remission or relapsed within 1 year of an initial alternating regimen, or not attained remission with two or more lines of treatment. At the time of ABMT the relapse status of the patients was as follows: 46 patients were primarily refractory to induction therapy, 7 were good partial responders, 52 were in first relapse, 37 in second relapse, and 13 in third relapse. Seventy-eight patients had chemoresistant disease, 33 had chemosensitive disease at the time of ABMT, and 44 were untested for chemosensitivity at latest relapse. The procedure related mortality in the first 90 days post-ABMT of 10% overall. At 3 months 43 patients (28%) were assessed as complete responders, 72 patients had a partial response (46%), and 24 patients (16%) had no response or progression of disease. However, by 6 months, 53 (24%) patients were assessed as complete responders and 51 (33%) patients had nonprogressive disease. Forty-five patients had received radiotherapy post-ABMT to residual masses (41 patients) or to previous sites of bulk disease (4 patients). The actuarial overall and progression-free survival at 5 years was 55% and 50%, respectively. On multivariate analysis patients with bulk (masses > 10 cm), heavily pretreated patients (those receiving three or more lines of treatment) and females had a significantly poorer prognosis. Relapse status was also significant for progression-free survival in that patients in second (60%) and third relapse (70%) had a better prognosis than those in first relapse (44%) or with primary refractory disease (33%). Response to prior chemotherapy did not predict for progression-free survival. These results enable comparisons to be made between high-dose chemotherapy with ABMT and conventional dose salvage therapy. Furthermore, although the results as a whole are highly encouraging, certain groups carry an unfavorable prognosis.     

Antenatal management of severe feto-maternal alloimmune thrombocytopenia: HLA incompatibility may affect responses to fetal platelet transfusions

In feto-maternal alloimmune thrombocytopenia (FMAIT), severe hemorrhage, particularly intracranial haemorrhage (ICH), may occur before delivery. Management strategies to prevent ICH in high-risk pregnancies include maternal administration of intravenous Ig with or without steroids and fetal platelet transfusions. This report describes a patient who lost three fetuses with ICH because of FMAIT due to anti- HPA-1a. ICH occurred earlier in successive pregnancies (at 28, 19, and 16 weeks of gestation) despite maternal treatment with intravenous Ig and steroids from 14 weeks of gestation in the third pregnancy. The fourth pregnancy was managed by administering weekly intraperitoneal injections of Ig to the fetus from 12 to 18 weeks of gestation. At 18 weeks, there was no evidence of ICH, but the fetal platelet count was only 12 x 10(9)/L. Serial fetal platelet transfusions were started, but there were poor responses because of immune destruction of the transfused platelets by maternal HLA antibodies. There were improved responses to transfusions prepared from the mother and from HLA- compatible HPA-1a-negative donors. At 35 weeks of gestation, a normal infant was delivered by Caesarean section after 20 platelet transfusions. There was prolonged thrombocytopenia in the baby for 15 weeks after birth, probably due to transfer of HPA-1a antibodies in the transfusions of unwashed maternal platelets. The optimal management of pregnancies likely to be severely affected by FMAIT is still evolving. Intensive management was successful in this case, but a successful outcome cannot be guaranteed in severely affected cases. This is the first time that HLA incompatibility has been found to complicate fetal transfusion therapy.     

Human fibrinogen polymorphic site analysis by restriction endonuclease digestion and allele-specific polymerase chain reaction amplification: identification of polymorphisms at positions A alpha 312 and B beta 448

In the fibrinogen molecule, a total of seven sites have been tentatively identified as polymorphic; however, disagreements about these sites have been observed among the various protein and DNA sequence data published. To allow examination of the potential polymorphic sites at the DNA level, human genomic DNA samples were prepared from 110 unrelated, healthy individuals. Either allele- specific polymerase chain reaction (ASPCR) amplification or PCR amplification followed by restriction endonuclease digestion was used to detect the presence of possible polymorphisms. Two polymorphic sites were confirmed, one at A alpha 312 (Thr/Ala) by RsaI restriction analysis, and a second at B beta 448 (Arg/Lys) by MnlI restriction analysis. Mendelian inheritance of both polymorphisms was demonstrated and allele frequencies were estimated as 0.76/0.24 and 0.85/0.15 for the A alpha 312 and B beta 448 sites, respectively. The sites at A alpha 47, A alpha 296, B beta 162, B beta 296, and gamma 88 showed no evidence of variation in any of our samples. The amino acid polymorphisms at A alpha 312 and B beta 448 reflect conservative residue changes with unknown effects on fibrinogen structure or function. An additional, previously unrecognized DNA sequence variant was detected in a single individual in the second intron of the A alpha chain using HinfI restriction analysis.     

Low molecular weight B-cell growth factor and recombinant interleukin-2 are together able to generate cytotoxic T lymphocytes with LAK activity from the bone marrow cells of children with acute lymphoblastic leukemia

We are reporting here that low-mol wt B-cell growth factor (LMW-BCGF) and recombinant interleukin-2 (rIL-2) are together able to induce CD3+ cytotoxic T lymphocytes (CTL) with lymphokine-activated killer cell (LAK) activity from the bone marrow (BM) cells of children with acute lymphoblastic leukemia (ALL). Ficoll-Hypaque (FH)-separated BM cells were obtained from patients with active disease (at diagnosis N = 13, in relapse N = 15) and in complete remission (CR; N = 12). CD3+ cells were removed by Leu-4 antibody and immunobeads. Cells were cultured (10(5) cells/mL) in semisolid media with rIL-2 (100 mu/mL), LMW-BCGF (0.1 mu/mL), and the combination of rIL-2 plus LMW-BCGF, respectively, for seven to ten days. Pooled colonies were harvested for phenotyping. LMW-BCGF plus rIL-2 induced large numbers of CD3+ colonies from CD3- precursors. rIL-2 alone did not induce colony formation. In addition, cells were cultured in liquid media with LMW-BCGF, rIL-2, and the combination of LMW-BCGF plus rIL-2, respectively, for seven to 21 days. They were harvested for phenotyping, and cytotoxicity assays were performed v K562, Raji, and autologous leukemic cells. LMW-BCGF plus rIL-2 induced significant expansion of CD3+ cells from CD3- precursors, and these cells were activated to kill autologous leukemic cells in addition to Raji and K562 cell lines. LMW-BCGF or rIL-2 alone did not induce significant expansion or activation of cytotoxic CD3- cells. Our hypothesis is that LMW-BCGF plus rIL-2 stimulates the proliferation and activation of CD3- precursors from the BM cells of children with acute leukemia to become CD3+ cells that have LAK activity. This finding may have therapeutic implications.     

Assay of prekallikrein in human plasma: comparison of amidolytic, esterolytic, coagulation, and immunochemical assays

Using the substrate H-D-Pro-Phe-Arg-p-nitroanilide-HCl, an amidolytic assay was designed to measure prekallikrein in plasma. At a substrate concentration of 1 mM (Km = 0.2 mM), the amidolysis of purified kallikrein at 1 coagulant unit/ml was observed to be 2.47 mumole/min/ml. Conditions for plasma prekallikrein activation were optimized to approach complete activation when compared to the amidolytic activity of the purified plasma kallikrein. Plasma treated with chloroform to destroy inhibitors of kallikrein was activated with dilute kaolin (final concentration 1 mg/ml) for 1 min at 25 degrees C. Activated plasma prekallikrein had 78% (1.92 mumole/min/ml) of activity of purified kallikrein at plasma concentration. Comparison of this amidolytic assay with immunochemical, esterolytic, and coagulant assays of three subject populations (normals, women on birth control pills, and patients with hepatocellular disease) showed good correlation both in normals and in the patient groups between the amidolytic and esterolytic assays (r = 0.89). Each enzymatic assay correlated with the immunochemical assay (r = 0.72, r = 0.68, respectively). However, comparison of each of these assays with the coagulant assay showed no significant correlation due to the large inherent error of the latter assay. This standardized plasma prekallikrein amidolytic assay should facilitate studies of plasma prekallikrein concentration in physiologic and pathologic conditions and help identify activation of the contact phase of coagulation in disease states.     

Factor XI antigen and activity in human platelets

Washed platelets, contaminated with less than 0.20% plasma factor XI, were examined for the presence of factor XI antigen and activity. These platelets contained a factor-XI-like coagulant activity (0.67 +/- 0.11 U/10(11) platelets) that remained constant after successive washes. By means of indirect immunofluorescence, a monospecific antibody to factor XI showed specific staining of both normal platelets and platelets from patients deficient in plasma factor XI. Radiolabeled Triton extracts of washed platelets and labeled purified factor XI solutions were analyzed for factor XI antigen by Staph A immunoprecipitation analysis using antibody to purified plasma factor XI followed by SDS gel electrophoresis. On unreduced gels, the platelet material ran as a single band having an apparent molecular weight of 220,000 daltons, whereas purified plasma factor XI gave a single band at 160,000 daltons. On reduced gels, the platelet material analyzed as a single band at 52,000 daltons, whereas purified factor XI gave a single band of 80,000 daltons. Analysis of a partially purified factor XI preparation from platelets by immunoelectrophoresis revealed that the platelet preparation displayed a slightly lower cathodal electrophoretic mobility at pH 8.6 than did plasma factor XI and yet appeared to possess complete antigenic identity with plasma factor XI. These results indicate that platelets possess a form of factor XI that exists as a disulfide-linked 52,000-dalton tetramer in contrast to the plasma form that circulates as a 80,000-dalton disulfide-linked dimer.