Search

The membrane topology of the bovine lens fiber cell plasma membrane protein MP20 has been examined using anti-peptide antibodies and the hydrophobic label 3-(trifluoromethyl)-3-( m -[ 125 I]iodophenyl)diazerine ([ 125 I]TID). The specificity of the affinity-purified anti-peptide polyclonal antibodies, directed against four separate hydrophilic segments of MP20, was established by immunodot blots, Western immunoblotting and ELISA. Western immunodetection of protease-treated, urea-washed lens membranes indicated that each of the segments of MP20 identified by the anti-peptide antibodies was accessible to proteases indicating their likely extramembranous location. Immunoelectron microscopy of junctional lens membrane immunolabeled with MP20 anti-peptide antibodies directed against two segments predicted to be on the extra-cellular face of the lens fiber cell plasma membrane suggests these segments may actually be located on the cytoplasmic plasma membrane face. Transmembrane segments of MP20, identified using the hydrophotic photo-affinity label [ 125 I]TID, were isolated and sequenced. Only three of the four previously proposed transmembrane segments of this protein were significantly labeled with this reagent. Based on these results and previously reported information regarding MP20, a new topological model is proposed for the arrangement of MP20 in the lens fiber cell plasma membrane. The new topological model of MP20 includes two α-helical and two β-strand transmembrane segments.

PURPOSE The phosphoprotein p53 is involved in transcriptional regulation and is detected in hematologic malignancies. In vitro incubation of acute myelogenous leukemia with OL(1)p53, a 20-mer phosphorothioate oligonucleotide complementary to p53 mRNA, results in leukemic cell death. A phase I dose-escalating trial was conducted to determine the toxicity of OL(1)p53 following systemic administration to patients with hematologic malignancies. PATIENTS AND METHODS Sixteen patients with either refractory acute myelogenous leukemia (n = 6) or advanced myelodysplastic syndrome (n = 10) participated in the trial. Patients were given OL(1)p53 at doses of 0.05 to 0.25 mg/kg/h for 10 days by continuous intravenous infusion. RESULTS No specific toxicity was directly related to the administration of OL(1)p53. One patient developed transient nonoliguric renal failure. One patient died of anthracycline-induced cardiac failure. Approximately 36% of the administered dose of OL(1)p53 was recovered intact in the urine. Plasma concentrations and area under the plasma concentration curves were linearly correlated with dose. Leukemic cell growth in vitro was inhibited as compared with pretreatment samples. There were no clinical complete responses. CONCLUSION A phosphorothioate oligonucleotide, OL(1)p53, can be administered systemically without complications. This type of modified oligonucleotide can be administered without complete degradation, as it was recovered from the urine intact. This oligonucleotide may be useful in combination with currently available chemotherapy agents for the treatment of malignancies.

Objectives:To determine the prevalence of aspergillosis in lymphoma patients housed in a protective environment while undergoing a bone marrow transplant or peripheral stem cell transplant and its relation to lymphoma type, type of transplant, period of neutropenia, method of diagnosis, species of Aspergillus, and the use of empiric amphotericin B.Design:Clinical, autopsy, and microbiology records were reviewed retrospectively to determine the presence or absence of invasive aspergillosis. All positive specimens underwent further review to determine parameters outlined above.Setting:The review took place at the University of Nebraska Medical Center with lymphoma patients housed in the oncology/hematology special care unit, which consists of 30 single-patient rooms under positive pressure with high-efficiency particulate air filtration.Patients:4 17 lymphoma patients admitted to the oncology/hematology special care unit who underwent 427 courses of high-dose chemotherapy with or without total body irradiation followed by a stem cell rescue.Results:Twenty-two cases (5.2%) of nosocomial invasive aspergillosis (14 caused by Aspergillus flavus, 2 by Aspergillus terreus, 2 by Aspergillus fumigatus, and 4 by characteristic histology) were diagnosed. The prevalence of disease according to transplant was 8.7% for allogeneic bone marrow transplant (2/23 treatments), 5.6% for autologous peripheral stem cell transplant (9/161), and 4.5% for autologous bone marrow transplant (11/243). Fifteen patients were presumptively diagnosed prior to death (68.2%) most commonly by histologic examination of skin biopsies. All 22 patients received amphotericin B therapy, 17 prior to aspergillosis diagnosis, and 7 (31.8%) survived. No patient with disseminated disease survived.Conclusions:Even when housing lymphoma patients undergoing myeloablative therapy in a protective environment containing high-efficiency particulate air filtration, there was a risk of developing aspergillosis. These data also showed that antemortem diagnosis with aggressive amphotericin B therapy was most effective in the management of infected lymphoma patients when engraftment occurred and the disease did not become disseminated.

MP20 is an intrinsic membrane protein previously identified in mammalian lens fiber cells. To identify a possible role for this protein in the lens, the distribution of MP20 and connexin46 has now been examined. Western immunoblotting with an anti-peptide antibody generated to the C-terminal 8 amino acids of MP20 confirmed the presence of this protein in the lens of several different mammalian species. A monoclonal antibody 5H1 was prepared that, in Western blots of bovine lesn membranes, recognized the same component as an antibody to rat connexin46 (Cx46). The apparent molecular mass of this component decreased from 59 kDa to 55 kDa following treatment of lens membranes with alkaline phosphatase. A monoclonal antibody to connexin-related MP70 recognized a 70 kDa component in bovine lens membranes confirming the presence of these two different connexin proteins in bovine lens membranes. To localize MP20 and Cx46 in the bovine lens membrane, lens fiber cell bundles were immunofluorescently labeled with both the MP20 antibody, and the monoclonal antibody to Cx46. Cx46 was identified in large plaques on the broad faces of the lens fiber cells throughout the outer 1 mm of the lens cortex. MP20 colocalized with Cx46 only in a restricted area 0.5 mm to 1.0 mm into the lens. In other regions of the lens, MP20 appeared more diffusely distributed over the fiber cell surface, although apparently concentrated in the ball-and-socket regions at the corners of the narrow side of the inner cortical lens fiber cells. These inner cortical regions were devoid of Cx46. A difference in distribution of these two proteins was confirmed in studies of immunofluorescently labeled lens cryosections. Furthermore, immunogold electron microscopy of purified lens membranes identified MP20 in both junctional regions (with Cx46) and in single membranes. These results provide evidence for a role for MP20 in mammalian lens fiber cell junctional formation or organization.

Pulmonary failure is a major contributor to morbidity and mortality during marrow aplasia following high-dose antineoplastic therapy. For this reason, we initiated a pulmonary surveillance program for patients undergoing high-dose chemotherapy for leukemia or bone marrow transplantation. As part of this program, bronchoscopy with BAL was performed prior to therapy and at the onset of granulocytopenia. Thirty-three of the first 57 patients managed in this program developed some evidence of pulmonary complications. Twelve patients died in aplasia; all had pulmonary failure. Forty patients had clinically significant abnormalities on the bronchoscopy before treatment, including 12 of 19 patients who had normal findings on chest x-ray films, physical examination, and pulmonary function testing, and no fever. Twenty-seven patients had clinically significant abnormal bronchoscopy or BAL at the onset of granulocytopenia. Thirteen patients required additional bronchoscopy. No patient required an open lung biopsy. Pulmonary surveillance using bronchoscopy with BAL is useful in the detection of pulmonary disease prior to the initiation of and following high-dose antineoplastic therapy. (Chest 1991; 99:105–11)

The cAMP-dependent protein-kinase-catalyzed phosphorylation of the two major intrinsic lens fiber cell plasma membrane proteins, MP20 and MP26, is likely restricted to the inner cortical and nuclear regions of the lens in vivo. The ovine-lens-specific connexin, MP70, that has been identified as Cx50 in mice and Cx45.6 in the chick, is also a protein kinase substrate although it does not appear to be phosphorylated by a number of protein kinases including cAMP-dependent protein kinase, calmodulin-dependent protein kinase or protein kinase C. Rather, an extrinsic lens membrane fraction was isolated which contained protein kinase activity that catalyzed the phosphorylation of MP70; this protein kinase activity was cAMP-independent, Ca(2+)-independent, Mg(2+)-dependent, phosphorylated MP70 on a serine residue(s) and migrated with a molecular mass of 35 kDa on a gel filtration column. Both MP70 phosphorylation and the endogenous protein kinase activity were restricted to the lens outer cortical region. This membrane-associated protein kinase activity represents the first reported partial characterization of an endogenous lens fiber cell protein kinase activity that catalyzes the phosphorylation of a lens connexin protein. The phosphatase-induced shift in the electrophoretic mobility of MP70 is not reversed by this protein kinase, indicating that MP70 is likely phosphorylated on different residues by two or more protein kinases.

A synthetic phosphorothioate oligonucleotide was administered systemically to five patients with either relapsed or refractory acute myelogenous leukemia (AML), or myelodysplastic syndrome (MDS). Patients received a 10-day continuous intravenous infusion of this compound, which is complementary to p53 mRNA. No major toxicity attributable to a dose of 0.05 mg/kg/hr was observed. A range of approximately 9 to 18% of the administered dose was recovered in the urine as intact oligonucleotide. Evaluation of malignant cells recovered from bone marrow and peripheral blood at intervals before, during, and after treatment reveals no enhanced growth potential following oligonucleotide administration. Hence, a phosphorothioate oligonucleotide complementary to p53 mRNA can be administered at this dose level to humans without major toxicity. Higher doses need to be evaluated for toxicity and potential clinical efficacy.

We determined risk factors present in patients with Hodgkin disease that predicted the development of diffuse alveolar hemorrhage syndrome (DAH) during autologous bone marrow transplantation (BMT). One hundred twenty-three patients with Hodgkin disease prospectively underwent bronchoscopy with bronchoalveolar lavage (BAL) before receiving BMT. The bronchitis index (BI) of the airways and bronchial and alveolar cell counts and differentials were determined in all patients and compared with 20 normal nonsmoking volunteers. Logistic regression analysis was used to determine factors that predicted for the development of DAH. Visual evidence of bronchial injury was observed regardless of smoking history (BI = 7.8 +/- 0.5 for BMT versus 2.3 +/- 0.5 for volunteers, p = 0.001). BMT patients who developed DAH (n = 14) had significantly greater numbers of bronchial neutrophils and eosinophils compared with DAH-negative (n = 109) patients (bronchial polymorphonuclear leukocytes (PMN), 33 +/- 7% versus 14 +/- 2%, p = 0.006; bronchial eosinophils, 0.9 +/- 0.3% versus 0.4% +/- 0.07%, p = 0.02). Logistic regression analysis revealed that the presence of bronchial PMN20% or bronchial eosinophilszero% were predictive of DAH (p = 0.005 and 0.05, respectively). When both predictors were positive, the rate of DAH was 10 times greater than when both predictors were negative (43% versus 4% DAH occurrence). Survival was also significantly reduced when these predictors were positive. This study demonstrates that bronchial inflammation is present with or without intraluminal inflammatory cells in the majority of patients with Hodgkin disease before BMT. The subgroup of these patients with increased bronchial inflammatory cells are at greatly increased risk for development of DAH and death.