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Biomedical subjects

O W Press

Publications and source records attributed to O W Press.

90 records · Page 5Linked to original sources
PubMed1986

A simplified microassay for inhibition of protein synthesis in reticulocyte lysates by immunotoxins.

We describe a simplified cell free reticulocyte lysate protein synthesis assay which has been shown to reliably demonstrate dose dependent inhibition of protein synthesis with cycloheximide and with four ricin A chain immunotoxin conjugates. Maximal [3H]leucine incorporation was observed using 40 microliter of reticulocyte lysate per microtiter well and by incubating samples for 30 minutes before harvesting with a multiple automated sample harvester. Trichloroacetic acid precipitation and hydrogen peroxide decolorization were not required with this method. This rapid, simplified assay system will facilitate testing of agents that inhibit protein synthesis, particularly immunotoxins.

Animals↗
PubMed1986

Evaluation of ricin A-chain immunotoxins directed against human T cells.

We have synthesized four immunotoxins (ITs) by covalently coupling the A chain of ricin to murine monoclonal antibodies that recognize surface antigens on human T cells. Treatment of human peripheral blood lymphocytes with either 10.2-A, directed against the CD5 (Tp67) antigen, or 64.1-A, directed against the CD3 (Tp19) antigen, abolished protein synthesis in cells subsequently cultured with phytohemagglutinin (PHA). In contrast, two other ITs (9.6-A and 35.1-A), both directed against the CD2 (Tp50) antigen, had minimal effects on protein synthesis in PHA-stimulated cells. The binding of each IT to T cells was shown by immunofluorescence with fluorescein-conjugated goat anti-mouse immunoglobulin (FITC-GAMIg) and fluorescein-conjugated rabbit anti-ricin A-chain (FITC-RAR) antibodies. Activity of the ricin A chain in each IT was demonstrated by its ability to inhibit protein synthesis in a cell-free reticulocyte lysate assay. Ultrastructural immunoperoxidase analysis of IT internalization showed that ineffective and effective ITs were endocytosed at the same rate (50% of cells had labeled endosomes after 15 min). However, ineffective IT 35.1-A was more rapidly delivered to lysosomes (15-30 min) than effective ITs (10.2-A and 64.1-A) (greater than or equal to 30 min). The data support the hypothesis that there are several distinct pathways for internalization of ITs and that the ability of ricin A chain to reach and inactivate ribosomes may depend upon the specific membrane receptor involved in binding a given IT, its route of internalization, and the rate of entry of the IT into lysosomes.

Antibodies, Monoclonal↗
PubMed1984

Central nervous system infections associated with hereditary hemorrhagic telangiectasia.

The clinical courses of 31 episodes of brain abscess and one episode of meningitis occurring in patients with hereditary hemorrhagic telangiectasia are reviewed. Pulmonary arteriovenous malformations were demonstrable in all but two patients and presumably permitted septic microemboli to evade the normal pulmonary capillary filter and lodge in the brain. Obtundation, headache, visual disturbances, hemiplegia, and seizures were the most common presenting features. Cyanosis, clubbing, polycythemia, and hypoxemia were routinely encountered, but leukocytosis and fever were present in a minority of cases, and all blood cultures were sterile. Anaerobic and microaerophilic streptococci were the commonest pathogens found in the brain abscesses. Thirteen patients died, and patients without abscess drainage or with delayed diagnosis had a higher mortality rate. A brain abscess may develop in approximately 1 percent of patients with hereditary hemorrhagic telangiectasia, and awareness of this risk should lead to early investigation of any patient with hereditary hemorrhagic telangiectasia who has neurologic symptoms.

Aged↗
PubMed1984

Hickman catheter infections in patients with malignancies.

The infectious complications associated with implantation of 1,088 Hickman catheters (HCs) in 992 patients reported in 18 published series are presented (including data on 129 previously unreported HCs from our own institution). HCs allow reliable long-term venous access (mean, 92.4 days) with low complication and infection rates (0.30 and 0.14 cases per 100 catheter days, respectively). Exit site infections were the most common form of infection encountered (45.5%), followed by septicemia alone (30.8%), tunnel infections (20.3%), and septic thrombophlebitis (3.5%). Staphylococcus epidermidis (54.1%) and S. aureus (20.0%) were the most common pathogens responsible for catheter infections. HC infections were associated with a low mortality rate (maximum rate of 0.5%). Risk factor analysis of 129 HCs demonstrated that catheter thrombosis was the major risk factor associated with development of catheter infection. Presence of fever, distant infection, neutropenia or antibiotic administration on the day of catheter insertion was not significantly associated with HC infection in this series (although there was a trend suggesting an increased risk of infection of HCs inserted during febrile episodes). Based on observations at our institution and from a review of the literature, tentative recommendations for management of the various types of HC infections are outlined.

Acute Disease↗
PubMed1983

Pseudotumor cerebri and hypothyroidism.

A 38-year-old obese woman with concurrent hypothyroidism and pseudotumor cerebri was monitored with serial thyroid function tests and CSF pressure determinations during levothyroxine sodium replacement therapy. Following normalization of the patient's thyroid status, assessed by both clinical and chemical indexes (serum thyroxine level, 1.5 to 11.0 micrograms/dL; serum thyrotropin level, 128 to 1.5 micro units/mL), intracranial hypertension persisted for more than four months. After weight loss, acetazolamide therapy, and intermittent CSF drainage failed to produce remission, glucocorticoid therapy was associated with prompt, sustained resolution of the pseudotumor cerebri. Contrary to previous reports, this patient's clinical course suggests that thyroid hormone deficiency and pseudotumor cerebri are not causally related.

Acetazolamide↗
PubMed1983

Pancytopenia in mannosidosis.

A case of autoimmune pancytopenia is described in a patient with mannosidosis who developed anti-platelet and anti-neutrophil antibodies and a low haptoglobin level. Bone marrow biopsy and 111InCl3 bone marrow scanning demonstrated hypoplasia of the marrow with a paucity of "storage cells." Pathogenic mechanisms and implications for other inborn errors of metabolism are discussed.

Adult↗
PubMed1982

Evaluation and management of chylous ascites.

Twenty-eight cases of chylous ascites occurring over the past 20 years are analyzed for clinical presentation, cause, yield of diagnostic procedure used, and response to therapy. Malignancies were responsible for 21 of 24 adult cases of chyloperitoneum, with lymphomas predominating (13 cases). The dismal prognosis in adult cases (12 patients died within 3 months) shows the need for appropriate diagnostic assessment including early lymph node biopsy or laparotomy, or both, when indicated. Surgery, chemotherapy, or radiation therapy should be instituted promptly except in cases resulting from surgical trauma to lymphatics, which frequently resolve with conservative management. Three of the four pediatric cases of chylous ascites resulted from congenital lymphatic anomalies; the fourth case resulted from operative trauma. Aggressive diagnostic and therapeutic interventions are not warranted in childhood cases of chylous ascites until conservative management (paracentesis, low-fat diet, medium-chain triglyceride supplementation) has failed; neoplasia is rarely implicated and many cases resolve within a few months.

Adult↗
PubMed1978

Differences in lifespan and rate of turnover between phytohaemagglutinin responsive cells of the bone marrow and of peripheral lymphoid organs.

Radioautographic analyses were performed on PHA stimulated cultures of in vivo labelled cells obtained from mice previously injected with 3H-TdR to selectively label either cells with a rapid renewal rate (RR) or a slow renewal rate (SR). ha responsive cells in the bone marrow (BM) were found to be virtually all RR cells, whereas both RR and SR cells from lymph nodes (LN) and spleen (Spl) were stimulated by this mitogen. However, RR cells were proportionately more responsive to PHA than SR cells in all tissues examined. Only one out of 200 BM PHA blasts belonged to the SR subclass, whereas the RR/SR ratio was approximately 1/1 for LN and 2/1 for Spl. Control experiments demonstrated that significant in vitro re-utilization of 3H-TdR from dying cells did not occur in the cultures. These results support a growing body of evidence that BM PHA responsive cells are precursor T-cells which are known to have a rapid turnover rate.

Animals↗
PubMed1977

Phytohemagglutinin-induced differentiation and blastogenesis of precursor T cells from mouse bone marrow.

The cells in mouse bone marrow (BM) capable of responding to phytohemagglutinin (PHA) were shown to be precursor T cells in experiments employing athymic mice, immunofluorescence, and specific lysis of T or B cells with cytotoxic antisera + complement. In contrast, the responses of lymph node (LN) and spleen (Spl) cells to this mitogen were shown by the same techniques to rely upon resident populations of mature T lymphocytes in these peripheral lymphoid organs. Cytolysis of T cells with anti-theta (anti-Thy 1), anti-thymocyte, or anti-brain antisera abolished the PHA responses of LN and Spl, but had no appreciable effect on the BM PHA response. Lysis of B cells with anti-mouse gamma globulin or anti-mouse IgM antisera had no significant effect on either Spl or BM blastogenesis in response to this lectin. Immunofluorescent studies with fluoresceinated anti-brain sera demonstrated acquisition of T-cell surface antigens by BM null lymphocytes during the blastogenic response of this tissue to PHA. The results of these immunofluorescence experiments were reproducible even when marrow obtained from nude mice and pretreated with anti-brain serum plus complement was employed. The implications of these findings with regard to prophylaxis against graft versus host disease in BM transplant recipients are discussed.

Animals↗
PubMedDate not supplied

Hemolytic activity of pH-responsive polymer-streptavidin bioconjugates.

Drug delivery systems that increase the rate and/or quantity of drug release to the cytoplasm are needed to enhance cytosolic delivery and to circumvent nonproductive cell trafficking routes. We have previously demonstrated that poly(2-ethylacrylic acid) (PEAAc) has pH-dependent hemolytic properties, and more recently, we have found that poly(2-propylacrylic acid) (PPAAc) displays even greater pH-responsive hemolytic activity than PEAAc at the acidic pHs of the early endosome. Thus, these polymers could potentially serve as endosomal releasing agents in immunotoxin therapies. In this paper, we have investigated whether the pH-dependent membrane disruptive activity of PPAAc is retained after binding to a protein. We did this by measuring the hemolytic activity of PPAAc-streptavidin model complexes with different protein to polymer stoichiometries. Biotin was conjugated to amine-terminated PPAAc, which was subsequently bound to streptavidin by biotin complexation. The ability of these samples to disrupt red blood cell membranes was investigated for a range of polymer concentrations, a range of pH values, and two polymer-to-streptavidin ratios of 3:1 and 1:1. The results demonstrate that (a) the PPAAc-streptavidin complex retains the ability to lyse the RBC lipid bilayers at low pHs, such as those existing in endosomes, and (b) the hemolytic ability of the PPAAc-streptavidin complex is similar to that of the free PPAAc.

Acrylates↗
PubMedDate not supplied

Localized beta dosimetry of 131I-labeled antibodies in follicular lymphoma.

The purpose of this study is to assess the multicellular dosimetry of 131I-labeled antibody in follicular lymphoma based on histological measurements on human tumor biopsy tissue. Photomicrographs of lymph node specimens were analyzed by first-order treatment to determine the mean values and statistical variations of the radii of follicles (260 +/- 90 microns), interfollicular distances (740 +/- 160 microns), and the number density of follicles [60 +/- 18 in a volume of (2 X 1480 microns)3]. Based on these measurements, two geometrical models were developed for localized beta dosimetry. The first, a regular cubic lattice model, assumes no variation in follicular radius of follicles and interfollicular distance. The second, a randomized distribution model, is a more complicated but more realistic representation of observed histological specimens. In this model, Monte Carlo methods were used to reconstruct the spatial distribution of follicles by simulating the distribution of the radii of follicles, interfollicular distances, and the number density of follicles. Dose calculations were performed using Berger's point kernels for absorbed-dose distribution for beta particles in water, assuming the 131I-labeled antibodies as point sources. It was assumed that the activity concentration of the labeled antibody within the follicles was ten times the activity concentration in the interfollicular spaces. The spatial distribution of localized dose was calculated for a tumor having an average dose of 40 Gy. The localized dose was found to be highly nonuniform, ranging from 20 to 90 Gy, and varying by a factor of about 2 from the average tumor dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗