Biomedical subjects

A Echeverri

Publications and source records attributed to A Echeverri.

8 recordsLinked to original sources

PubMed1999

Human herpesvirus 8-encoded interleukin 6 activates HIV-1 in the U1 monocytic cell line.

OBJECTIVE: Human herpesvirus 8 (HHV-8) encodes a viral interleukin 6 (vIL-6) which is structurally and functionally similar to human interleukin 6 (hIL-6). Since hIL-6 has been shown to upregulate the expression of HIV-1, the objectives of this study were to examine the ability of vIL-6 to upregulate HIV-1, and to determine the interactions of this virokine (viral cytokine) with the components of the interleukin 6 (IL-6) receptor complex. DESIGN AND METHODS: Recombinant HHV-8 vIL-6 (rvIL-6) was assayed for bioactivity in the IL-6-dependent cell line MH60.BSF2. HIV-1 p24 production by the U1 monocytic and ACH-2 T-cell lines, which are chronically infected with HIV-1, was used to assess the ability of vIL-6 to affect HIV-1 expression. hIL-6 and vIL-6 receptor utilization was determined by quantifying HIV-1 p24 production after neutralization of components of the IL-6 receptor complex, CD126'IL-6R' and CD130'gp130', on U1 cells with blocking antibodies. RESULTS: HHV-8 rvIL-6 was seen to have IL-6-like bioactivity in MH60.BSF2 cells, and readily upregulated HIV-1 p24 production in U1 monocytic cells, but not in ACH-2 T cells. The vIL-6 appeared to utilize the IL-6-specific component of the IL-6 signaling complex, CD126'IL-6R', in U1 cells. CONCLUSIONS: HHV-8 vIL-6 clearly has the potential to upregulate HIV-1 expression in monocytic cells, and therefore may play a role in AIDS pathogenesis in individuals infected with both viruses.

Animals↗

PubMed1999

Pulmonary dirofilariasis.

BACKGROUND: Pulmonary dirofilariasis is a rare entity caused by Dirofilaria immitis, the dog heartworm that is transmitted to humans by mosquitos. This filarial nematode enters the subcutaneous tissue, travels to the right ventricle where it dies, and then embolizes the pulmonary vasculature, causing a small pulmonary infarction, which subsequently appears as a solitary nodule. Although these nodules are usually identified incidentally by chest radiography in asymptomatic patients, the lesion is generally presumed to be neoplastic. Diagnosis is made by surgical excision. METHODS: We reviewed the pathology reports at Memorial Medical Center, Savannah, GA since 1990. RESULTS: There have been approximately 150 cases reported in the literature worldwide. We found 4 patients with pulmonary dirofilariasis diagnosed at our hospital since 1992. A review of the pathogenesis of the disease and clinical manifestations, diagnosis, and treatment of this entity are presented. CONCLUSIONS: Pulmonary dirofilariasis is a benign condition, transmitted by mosquitos to humans that results in peripheral pulmonary nodules. Awareness of this entity is important in the differential diagnosis of pulmonary coin lesions.

Adult↗

PubMed1998

Amino-terminal region of poliovirus 2C protein is sufficient for membrane binding.

The poliovirus-encoded, membrane associated polypeptide 2C is required for viral replication. We have previously established that, while the 2C protein lacks a defined membrane binding domain, the N-terminal region containing a putative amphipathic helix plays an important role in membrane binding both in vivo and in vitro. In order to determine whether the N-terminal region is sufficient for membrane binding, we have made fusion constructs between this region of 2C (amino acids 1-72 and 1-88) and a soluble protein, chloramphenicol acetyltransferase (CAT). The ability of CAT and the fusion polypeptides to bind to membranes was examined by in vitro translation in the presence of microsomal membrane. While CAT was found in the soluble fraction, both 2C/CAT fusion constructs (1-72/CAT and 1-88/CAT) were membrane associated, suggesting that the N-terminal region of 2C was sufficient to impart membrane binding. To confirm these results in vivo, CAT, 1-72/CAT, and 1-88/CAT were expressed in HeLa cells and their localization was examined using indirect immunofluorescence. Results presented here demonstrate that, while CAT is expressed throughout the cell, 1-72/CAT and 1-88/CAT constructs are capable of localizing to the endoplasmic reticulum (ER) area in transfected cells in the absence of other poliovirus proteins. These results suggest that the first 72 amino acids of 2C contain a membrane binding domain that is capable of targeting soluble proteins to the ER region of the cell.

Binding Sites↗

PubMed1998

Electrophysiologic nerve stimulation for identifying the recurrent laryngeal nerve in thyroid surgery: review of 70 consecutive thyroid surgeries.

To describe a simple technique for identifying the recurrent laryngeal nerve (RLN) with a nerve stimulator to prevent damage to the nerve during thyroid surgery. A retrospective review of 70 thyroidectomies performed from October 1989 to January 1995 by one surgeon using electrophysiologic nerve stimulation to identify the RLN was conducted. The technique is described. Outpatient flexible fiberoptic laryngoscopy was performed preoperatively and postoperatively in all patients. From 70 thyroidectomies, 80 RLNs were identified to be at risk for injury. Five patients had transient unilateral vocal cord paresis postoperatively. No RLN transection or permanent vocal cord paralysis occurred. This is the first large series of patients undergoing the use of electrophysiologic nerve stimulation for identifying the RLN during thyroid surgery. We found the technique to be useful and safe for identifying the RLN. We present this technique as a less costly and time-consuming alternative to intraoperative RLN monitoring.

Adolescent↗

PubMed1997

Poliovirus-encoded 2C polypeptide specifically binds to the 3'-terminal sequences of viral negative-strand RNA.

The poliovirus-encoded, membrane-associated polypeptide 2C is believed to be required for initiation and elongation of RNA synthesis. We have expressed and purified recombinant, histidine-tagged 2C and examined its ability to bind to the first 100 nucleotides of the poliovirus 5' untranslated region of the positive strand and its complementary 3'-terminal negative-strand RNA sequences. Results presented here demonstrate that the 2C polypeptide specifically binds to the 3'-terminal sequences of poliovirus negative-strand RNA. Since this region is believed to form a stable cloverleaf structure, a number of mutations were constructed to examine which nucleotides and/or structures within the cloverleaf are essential for 2C binding. Binding of 2C to the 3'-terminal cloverleaf of the negative-strand RNA is greatly affected when the conserved sequence, UGUUUU, in stem a of the cloverleaf is altered. Mutational studies suggest that interaction of 2C with the 3'-terminal cloverleaf of negative-strand RNA is facilitated when the sequence UGUUUU is present in the context of a double-stranded structure. The implication of 2C binding to negative-strand RNA in viral replication is discussed.

Base Sequence↗

PubMed1988

Long-term results of hip arthroplasty for failure of previous surgery.

We report a retrospective review of 127 low friction arthroplasties carried out for the failure of a previous hip operation. After an average follow-up of 10.4 years, 20% of cases required further revision, over half of them for deep infection. We estimated from the radiographic appearances that eventual failure by loosening was probable in 58% on the femoral side and 56% on the acetabular side of the arthroplasties.

Adolescent↗

PubMed1978

Cell-mediated immunity in anergic patients with pulmonary tuberculosis.

Twelve adults with confirmed pulmonary tuberculosis who failed to respond to repeated skin tests with 250 TU of second-strength purified protein derivative of tuberculin were studied using in vivo and in vitro tests of cell-mediated immunity. All but 2 of the patients failed to respond to skin tests with candidin and histoplasmin, and only one could be sensitized with topical applications of dinitrochlorobenzene. The blastogenic response of peripheral blood lymphocytes from these anergic patients, when cultured in the presence of phytohemagglutinin, pokeweed mitogen, and purified protein derivative, was significantly less than that of lymphocytes from tuberculin-positive control patients. During the course of therapy with isoniazid and streptomycin, 6 of the anergic patients converted spontaneously and reacted positively to purified protein derivative. This skin-test conversion was accompanied by a significant increase in the blastogenic response of lymphocytes from the converted patients when cultured with purified protein derivate. Tuberculin anergy in these 12 patients was not associated with progessive, disseminated disease. All patients responded successfully to the primary chemotherapeutic regimen.

Adolescent↗

PubMedDate not supplied

Immune dysfunction and the pathogenesis of AIDS-associated non-Hodgkin's lymphoma.

Much has been learned about how HIV-induced immune dysfunction contributes to B cell hyperactivation, and potentially, to the pathogenesis of AIDS-lymphoma. However, further studies are needed to fully understand how HIV infection and immune dysfunction promote B cell hyperactivation and the development/growth of AIDS-lymphoma. In particular, studies are needed to define the role of HHV8 vIL6, IL6 receptor-expression, and lymphocyte surface stimulatory molecules, in promoting B cell hyperactivation or lymphoma cell growth.

B-Lymphocytes↗