Biomedical subjects

P S Smitt

Publications and source records attributed to P S Smitt.

5 recordsLinked to original sources

PubMed2001

Treatment of malignant gliomas with a replicating adenoviral vector expressing herpes simplex virus-thymidine kinase.

We evaluated the interaction between oncolytic, replication-competent adenoviral vectors and the herpes simplex virus-1 thymidine kinase (HSV1-tk) gene/ganciclovir (GCV) suicide system for the treatment of malignant gliomas. We constructed a panel of replication-competent adenoviral vectors in which the luciferase (IG.Ad5E1(+). E3Luc) or HSV1-tk gene (IG.Ad5E1(+).E3TK) replace the M(r) 19,000 glycoprotein (gp19K) coding sequence in the E3 region. IG.Ad5E1. IG.Ad5.ClipLuc and IG.AdApt.TK are E1-deleted viruses that contain the luciferase or the HSV1-tk gene in the former E1 region driven by the human cytomegalovirus promoter. IG.Ad5. Sarcoma 1800HSA.E3Luc contains an irrelevant gene in the E1 region, whereas the gp19K coding sequence in the E3 region is replaced by the luciferase gene as in the replicating virus IG.Ad5E1(+).E3Luc. For in vitro experiments, we used a panel of human glioma cell lines (U87 MG, T98G, A172, LW5, and U251), a rat gliosarcoma cell line (9 L), and human lung (A549) and prostate carcinoma (P3) cell lines. In vitro, GCV sensitivity (10 microg/ml) was studied in U87 MG cells after infection at a multiplicity of infection of 1 and 10. A s.c. U87 MG glioma xenograft model was established in NIH-bg-nu-xid mice. Tumors of 100-150 mm(3) were treated with a single injection of adenovirus 10(9) IU suspended in 100 microl of PBS, and GCV 100 mg/kg was administered i.p. twice daily for 7 days. The cytopathic effect of all three replication-competent adenoviral vectors was similar to the cytopathic effect of wild-type adenovirus 5 on all human cell lines tested, indicating that deletion of the E3 gp19K sequences did not affect the oncolytic effect of the vectors. In vitro, luciferase expression was the same for both E1-deleted vectors (IG.Ad5.ClipLuc and IG.Ad5. Sarcoma 1800HSA.E3Luc), demonstrating the strength of the internal E3 promoter even in the absence of E1A. However, in vitro expression levels obtained with replication-competent IG.Ad5E1(+). E3Luc were 3 log higher (allowing infection with a 2-3-log lower multiplicity of infection) in the human cell lines. In U87 MG glioma cells, the oncolytic effect of replication-competent IG.Ad5E1(+).E3TK was significantly enhanced by the addition of GCV and greatly exceeded the cytotoxicity of replication-incompetent IG.AdApt.TK combined with GCV. In established s.c. U87 MG glioma xenografts, a single injection of IG.Ad5E1(+).E3TK resulted in a significant slowing of tumor growth and prolonged survival compared with injection of IG.AdApt.TK. Addition of GCV slowed tumor growth, further adding to survival. In conclusion, the oncolytic effect of replicating adenoviral vectors and HSV1-tk/GCV have potent antitumor effects in gliomas. When combined, these two approaches are complementary, resulting in a significantly improved treatment outcome. In addition, replication-competent adenoviral vectors missing the E3 gp19K coding sequences, have oncolytic efficacy comparable with wild type. In combination with high expression levels obtained with the natural E3 promoter, such vectors are promising new anticancer agents.

Adenoviridae↗

PubMed1998

Outcome and complications of epidural analgesia in patients with chronic cancer pain.

BACKGROUND: Some cancer patients require invasive techniques for control of chronic cancer pain. Many patients have benefited from local administration of opioids and anesthetics through an epidural catheter. However, epidural abscess and meningitis are side effects of epidural catheters that have serious morbidity and mortality. METHODS: In a retrospective study, the charts of all patients who received an epidural catheter for the management of chronic cancer pain in a 3-year period (1993-1996) were reviewed. Patients with nervous system infections were identified and pertinent clinical, radiologic (magnetic resonance imaging), and bacteriologic data were analyzed. RESULTS: Ninety-one patients received 137 epidural catheters for a total of 4326 catheter days. All but four patients had died at the time of the final analysis. The median survival after placement of the first epidural catheter was 38 days (range, 1 day--> 1000 days). Seventy-two patients received a percutaneous port whereas 19 patients were treated with an implanted subcutaneous port. Adequate pain relief was obtained in 76% of the 58 patients with nociceptive pain and in 73% of 33 patients with neuropathic pain. All neuropathic pain was associated with active tumor and could be classified as nociceptive nerve pain. Technical complications and superficial infections occurred in as many as 43% of patients. Deep infections occurred in 12 patients, 11 of whom had a spinal epidural abscess. CONCLUSIONS: Deep infection is a frequent complication of epidural analgesia and is associated with a high morbidity and mortality. Only cancer patients with a short life expectancy (< or =3 months) should be treated with epidural analgesia.

Adult↗

PubMed1997

HuD, a neuronal-specific RNA-binding protein, is a potential regulator of MYCN expression in human neuroblastoma cells.

HuD is one of a family of neural antigens recognised by the sera of patients with antibody-associated paraneoplastic encephalomyelitis. Localised exclusively to neurons, these proteins are among the earliest markers of the developing nervous system. Sequence analysis suggests that HuD is an RNA-binding protein. Hu protein levels were determined for the three cell types characterising human neuroblastoma cell lines: sympathoadrenal neuroblasts (N), substrate-adherent Schwann/glial/melanoblastic precursors (S) and stem cells (I) which can give rise to both N and S cells. Western blot analysis showed similar levels of protein in three N-type cell lines; S cells have no detectable Hu protein. Northern blot analysis indicated that N cells express all three Hu genes, HuD, HuC and Hel-N1. N cells, mostly from MYCN-amplified cell lines, have consistently higher steady-state levels of MYCN mRNA than S cell counterparts. Nuclear run-on and mRNA half-life experiments revealed no differences in transcription rate or mRNA stability between N and S cells from the LA-N-1 cell line, implicating differences in post-transcriptional regulation. HuD is postulated to be instrumental in splicing/processing and/or stabilisation of mRNAs involved in cell growth and neuronal differentiation. As determined by gel-mobility shift assays, HuD fusion protein binds to the 3'UTR of human MYCN mRNA. Analysis of HuD deletion mutants has demonstrated that the first and second RNA-recognition motifs (RRMs) are required for binding. Whether HuD regulates MYCN expression and thereby influences tumour aggressiveness is of major interest.

Binding Sites↗

PubMed1995

Hu antigens: reactivity with Hu antibodies, tumor expression, and major immunogenic sites.

HuD, a human neuronal RNA-binding protein, was the first identified member of a family of antigens that also includes HuC and Hel-N1 (Hu antigens). The serum of all patients with anti-Hu-associated paraneoplastic encephalomyelitis and sensory neuronopathy react with HuD and Hel-N1, but the reactivity with HuC is unknown. In the current study we examined (1) the reactivity of anti-Hu sera with HuD, HuC, and Hel-N1; (2) the expression of HuD, HuC, and Hel-N1 messenger RNA in small-cell lung cancer of patients with and those without paraneoplastic encephalomyelitis/sensory neuronopathy; (3) the correlation between anti-Hu serum reactivity with these three Hu antigens and the type of neurological symptoms; and (4) the major immunogenic sites of HuD. Our findings indicate that all anti-Hu sera react with HuD, HuC, and Hel-N1. However, only HuD is expressed in the small-cell lung cancer tumors, indicating that among the three Hu antigens, HuD appears to play a central role in triggering the anti-Hu immune response. No differences were identified regarding the reactivity of the anti-Hu antibodies with HuD, HuC, and Hel-N1 and the spectrum of neurological symptoms presented by the patients. Study of the major immunogenic sites of HuD resulted in the identification of two major immunodominant regions with at least two distinct epitopes recognized by the serum of all patients with anti-Hu-associated paraneoplastic encephalomyelitis/sensory neuronopathy.

Adolescent↗

PubMed1995

Paraneoplastic peripheral neuropathy.

Paraneoplastic peripheral neuropathies are not common. They are out-numbered by the far more common peripheral neuropathies that occur either as a direct result of the cancer (metastases) or its treatment (usually chemotherapy). Nevertheless, paraneoplastic peripheral neuropathies are important because they may be the first sign of an otherwise occult cancer and/or because they may substantially disable the patient even when the cancer itself is asymptomatic. Paraneoplastic disorders are sometimes marked by the presence of autoantibodies that react with proteins both in the underlying cancer and in the nervous system. Their discovery may lead to an early diagnosis and potential cure of the underlying cancer.

Autoantibodies↗