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Biomedical subjects

J M Martin

Publications and source records attributed to J M Martin.

At least 19 recordsLinked to original sources
PubMed2003

Age of menarche: the role of some psychosocial factors.

BACKGROUND: The goal of this study was to determine associations between the age of first menstrual period (menarche) and adverse childhood experiences in a random community sample of New Zealand women. Previous reports have linked early menarche to absence of a live-in father figure and to family conflict, as well as genetic determination of early puberty and adiposity. METHOD: Two groups of women randomly selected from the community on their responses to a mailed screening questionnaire on childhood sexual abuse (CSA) were interviewed in detail. Data about their childhood experiences, including age of menarche, were collected on two occasions, 6 years apart. Early menarche was defined as first menstruation occurring before the age of 12 years. RESULTS: Univariate analyses identified a number of adverse childhood experiences preceded early menarche, which was reported by 20.3% of this sample. These included low family socio-economic status, absence of father, a number of variables showing family conflict, poor relationships between the girl and either/both parents, a self-rated childhood personality style as a loner, childhood physical and sexual abuse. Sequential modelling showed parental rows, being a loner and the duration of CSA to be most important, although lack of a father and any CSA were each also independently associated with early menarche. No variables survived the modelling exercise as predictors of early menarche for those women who did not report childhood sexual abuse. CONCLUSIONS: The identified variables statistically interacted with each other in a highly complex manner. The attempt to rank their importance was only partially successful, for methodological reasons (half the sample reporting CSA). Chronic or protracted CSA needs to be added to the list of factors associated with early menarche in future studies.

Adult↗
PubMed2003

Female sexual health care in cystic fibrosis.

Fifty five teenage girls with cystic fibrosis and their mothers were interviewed to assess the provision of sexual health information. Parents were the most common source of information for adolescents. The cystic fibrosis doctor was identified as the key resource for parents. Yet few parents had spoken to their doctor about these issues, and 96% requested more information. This information was wanted before puberty by mothers, and from puberty onwards by girls.

Adolescent↗
PubMed2002

Isolated primary Langerhans' cell histiocytosis of central nervous system.

Solitary eosinophilic granuloma that involves the CNS is an uncommon lesion and most frequently affects the hypothalamus. We report a new and rare case of solitary eosinophilic granuloma of the left temporal lobe in a patient without systemic disease. The diagnosis was confirmed by electron microscopy and immuohistochemical techniques. The treatment of choice is surgical resection. There is a better prognosis in comparison with cases accompanied by systemic disease.

Adult↗
PubMed2002

Hordoindolines are associated with a major endosperm-texture QTL in barley (Hordeum vulgare).

Endosperm texture has a tremendous impact on the end-use quality of wheat (Triticum aestivum L.). Cultivars of barley (Hordeum vulgare L.), a close relative of wheat, also vary measurably in grain hardness. However, in contrast to wheat, little is known about the genetic control of barley grain hardness. Puroindolines are endosperm-specific proteins found in wheat and its relatives. In wheat, puroindoline sequence variation controls the majority of wheat grain texture variation. Hordoindolines, the puroindoline homologs of barley, have been identified and mapped. Recently, substantial allelic variation was found for hordoindolines among commercial barley cultivars. Our objective was to determine the influence of hordoindoline allelic variation upon grain hardness and dry matter digestibility in the 'Steptoe' x 'Morex' mapping population. This population is segregating for hordoindoline allele type, which was measured by a HinA/HinB/Gsp composite marker. One-hundred and fifty lines of the 'Steptoe' x 'Morex' population were grown in a replicated field trial. Grain hardness was estimated by near-infrared reflectance (NIR) and measured using the single kernel characterization system (SKCS). Variation attributable to the HinA/HinB/Gsp locus averaged 5.7 SKCS hardness units (SKCS U). QTL analysis revealed the presence of several areas of the genome associated with grain hardness. The largest QTL mapped to the HinA/HinB/Gsp region on the short arm of chomosome 7 (5H). This QTL explains 22% of the SKCS hardness difference observed in this study. The results indicate that the Hardness locus is present in barley and implicates the hordoindolines in endosperm texture control.

Hordeum↗
PubMed2001

Comparison of steric and electronic requirements for C-C and C-H bond activation. Chelating vs nonchelating case.

C-H bond activation was observed in a novel PCO ligand 1 (C(6)H(CH(3))(3)(CH(2)OCH(3))(CH(2)P(t-Bu)(2))) at room temperature in THF, acetone, and methanol upon reaction with the cationic rhodium precursor, [Rh(coe)(2)(solv)(n)()]BF(4) (solv = solvent; coe = cyclooctene). The products in acetone (complexes 3a and 3b) and methanol (complexes 4a and 4b) were fully characterized spectroscopically. Two products were formed in each case, namely those containing uncoordinated (3a and 4a) and coordinated (3b and 4b) methoxy arms, respectively. Upon heating of the C-H activation products in methanol at 70 degrees C, C-C bond activation takes place. Solvent evaporation under vacuum at room temperature for 3-4 days also results in C-C activation. The C-C activation product, ((CH(3))Rh(C(6)H(CH(3))(2)(CH(2)OCH(3))(CH(2)P(t-Bu)(2))BF(4)), was characterized by X-ray crystallography, which revealed a square pyramidal geometry with the BF(4)(-) anion coordinated to the metal. Comparison to the structurally similar and isoelectronic nonchelating Rh-PC complex system and computational studies provide insight into the reaction mechanism. The reaction mechanism was studied computationally by means of a two-layer ONIOM model, using both the B3LYP and mPW1K exchange-correlation functionals and a variety of basis sets. Polarization functions significantly affect relative energetics, and the mPW1K profile appears to be more reliable than its B3LYP counterpart. The calculations reveal that the electronic requirements for both C-C and C-H activation are essentially the same (14e intermediates are the key ones). On the other hand, the steric requirements differ significantly, and chelation appears to play an important role in C-C bond activation.

Journal Article↗
PubMed2001

The cytoplasmic amino-terminus of the Latent Membrane Protein-1 of Epstein-Barr Virus: relationship between transmembrane orientation and effector functions of the carboxy-terminus and transmembrane domain.

The Latent Membrane Protein 1 (LMP-1) protein of Epstein-Barr virus (EBV) is localized in the plasma membrane of the infected cell. LMP-1 possesses a hydrophobic membrane spanning domain, and charged, intracellular amino- and carboxy-termini. Two models have been proposed for the contribution of the amino-terminus to LMP-1's function: (i) as an effector domain, interacting with cellular proteins, or (ii) as a structural domain dictating the correct orientation of transmembrane domains and thereby positioning LMP-1's critical effector domains (i.e. the carboxy-terminus). However, no studies to date have addressed directly the structural contributions of LMP-1's cytoplasmic amino-terminus to function. This study was designed to determine if LMP-1's cytoplasmic amino-terminus (N-terminus) encodes information required solely for maintenance of proper topological orientation. We have constructed LMP-1 chimeras in which the cytoplasmic N-terminus of LMP-1 is replaced with an unrelated domain of similar size and charge, but of different primary sequence. Retention of the charged amino-terminal (N-terminal) cytoplasmic domain and first predicted transmembrane domain was required for correct transmembrane topology. The absolute primary sequence of the cytoplasmic N-terminus was not critical for LMP-1's cytoskeletal association, turnover, plasma membrane patching, oligomerization, Tumor Necrosis Factor Receptor-associated factor (TRAF) binding, NF-kappaB activation, rodent cell transformation and cytostatic activity. Furthermore, our results point to the hydrophobic transmembrane domain, independent of the cytoplasmic domains, as the primary LMP-1 domain mediating oligomerization, patching and cytoskeletal association. The cytoplasmic amino-terminus provides the structural information whereby proper transmembrane orientation is achieved.

Amino Acid Sequence↗
PubMed2001

Computational study of a new heck reaction mechanism catalyzed by palladium(II/IV) species.

In this theoretical study on the Heck reaction we explore the feasibility of an alternative pathway that involves a PdII/PdIV redox system. Usually, the catalytic cycle is formulated based on a Pd0/PdII mechanism. We performed quantum chemical calculations using density functional theory on a model system that consisted of diphosphinoethane (DPE) as a bidentate ligand and the substrates ethylene and phenyl iodide to compare both mechanisms. Accordingly, the PdII/PdIV mechanism is most likely to occur in the equatorial plane of an octahedral PdIV complex. The energy profiles of both reaction pathways under consideration are largely parallel. A major difference is found for the oxidative addition of the C-I bond to the palladium centre. This is a rate-determining step of the PdII/PdIV mechanism, while it is facile for a Pd0 catalyst. The calculations show that intermediate ligand detachment and reattachment is necessary in the course of the oxidative addition to PdII. Therefore, we expect the PdII/PdIV mechanism to be only feasible if a weakly coordinating ligand is present.

Journal Article↗
PubMed2001

A fully ab initio potential curve of near-spectroscopic quality for OH- ion: importance of connected quadruple excitations and scalar relativistic effects.

A benchmark study has been carried out on the ground-state potential curve of the hydroxyl anion, OH-, including detailed calibration of both the l-particle and n-particle basis sets. The CCSD(T) basis set limit overestimates omega(e) by about 10 cm(-1), which is only remedied by inclusion of connected quadruple excitations in the coupled cluster expansion--or, equivalently, the inclusion of the 2pi orbitals in the active space of a multireference calculation. Upon inclusion of scalar relativistic effects (-3 cm(-1) on omega(e)), a potential curve of spectroscopic quality (sub-cm(-1) accuracy) is obtained. Our best computed EA(OH), 1.828 eV, agrees to three decimal places with the best available experimental value. Our best computed dissociation energies, D0(OH-) = 4.7796 eV and D0(OH) = 4.4124 eV, suggest that the experimental D0(OH) = 4.392 eV may possibly be about 0.02 eV too low.

Astronomical Phenomena↗
PubMed2001

Localized non-Hodgkin's lymphoma of Waldeyer's ring: clinical features, management, and prognosis of 130 adult patients.

BACKGROUND: Waldeyer's ring (WR) is the primary site of non-Hodgkin's lymphoma (NHL) involvement in approximately 5% to 10% of all lymphoma patients, and it accounts for more than half of all primary extranodal lymphomas of the head and neck. Materials and Methods A retrospective review was performed of 130 adult patients with localized (stages I and II) WR-NHL seen at a single institution over 18 years. RESULTS: Patients had a median age of 55 years, and the male-female ratio was 1:5:1. Seventy five (58%), 46 (35%), and 9 (7%) patients had primary tonsillar, nasopharyngeal, and base of the tongue lymphoma, respectively. Forty-five (35%) and 85 (65%) had stage I and stage II disease, respectively. Most patients (109 patients, 84%) had diffuse large B-cell NHL (DLC). Chemotherapy (CT) was given to 58 (45%) patients, whereas 26 (20%) received radiation therapy (RTX), and 46 (35%) were managed with a combination of chemotherapy and radiotherapy (CMT). One hundred nine (84%), 16 (12%), and 5 (4%) patients attained complete remission (CR), partial remission (PR), and treatment failure, respectively, with no difference in CR rates between the three therapeutic modalities. Of those patients with DLC, 90 (83%), 15 (14%), and 4 (3%) demonstrated CR, PR, and treatment failure, respectively. In a multivariate analysis, the modified International Prognostic Index (IPI) was found to predict the attainment of CR. Over a median follow-up of 49 months; 76 (58%) of the patients were alive and disease-free, 5 (4%) were alive with evidence of disease, and the remaining 49 (38%) were dead. Most distant relapses were in nongastrointestinal extranodal sites. The median overall survival (OS) has not been reached; however, the projected 5-year OS was 58%. No OS difference was noted between patients with stage I and stage II. Cox proportional hazards model identified primary tonsillar site and a low-risk group as defined by the modified IPI were associated with favorable OS. The median event-free survival was 82.3 months, with the primary tonsillar site, and low-risk modified IPI group were associated with favorable EFS in a multivariate analysis. Probably because of the high frequency of patients with DLC, the outcome and the prognostic factors in those patients were not distinctive from those for the whole group. The CMT was not associated with a superior OS compared with either of the single modality treatments; however, it was associated with more favorable EFS. CONCLUSIONS: This series characterized the clinicopathologic features and outcome of adult patients with early stage WR-NHLs. No survival difference was noted between stage I and stage II, and the outcome was favorable. Primary tonsillar site and the low-risk group of the modified IPI predicted favorable OS and EFS. CMT is probably superior to single modality treatment; however, prospective studies are warranted.

Adolescent↗
PubMed2001

Primary intestinal diffuse large B-cell non-Hodgkin's lymphoma: clinical features, management, and prognosis of 66 patients.

BACKGROUND: In Saudi Arabia, primary gastrointestinal non-Hodgkin's lymphoma (NHL) is common. Recently we have reported one of the largest series of primary gastric (PG) diffuse large B-cell lymphoma (DLCL). This has prompted the analysis of another series of patients with primary intestinal DLCL to depict the clinical features and the outcome of that disease and to compare those with that for PG involvement. PATIENTS AND METHODS: The data of 66 adult patients with primary intestinal NHL having DLCL histology were retrospectively reviewed. RESULTS: Patients had a median age of 45 years. Of 64 treated patients, 16% and 84%, received single and multiple modality treatment, respectively. Seventy-six percent, ten percent, and fourteen percent attained complete remission (CR), partial remission (PR), and no response/progressive disease, respectively. Multivariate analysis failed to identify any variable that predict the likelihood of attaining CR. Over a median follow-up of 81 months for all 66 patients, 32 (48%) were alive and disease-free, 5 (8%) were alive with evidence of disease, and the remaining 29 (44%) were dead. The median overall survival (OS) was 101 months and it was 58% (+/- 6%) and 48% (+/- 7%) at 5- and 10-year, respectively. Of the 54 patients who achieved CR or PR, the median event-free survival (EFS) was not reached, but the predicted 5- and 10-year EFS was 61% (+/- 7%) and 52% (+/- 7%), respectively. Only low serum albumin (<30 g/l) was associated with adverse OS and EFS in a univariate analysis, however, multivariate analysis was not possible. Our analysis showed that compared with single-modality management, multi-modality strategy attained significantly higher CR, and advantageous EFS, but without a significant superior effect on OS. In comparison with patients with PG DLCL, those with primary intestinal disease demonstrated more adverse prognostic features, but had an equivalent survival. CONCLUSIONS: This series characterized the clinico-pathologic features and outcome of patients with primary intestinal DLCL. While surgical resection in primary intestinal NHL seems beneficial, only prospective randomized studies can ascertain its precise role. Compared with patients with PG NHL, patients with primary intestinal disease had more prevalence of adverse prognostic features.

Adolescent↗
PubMed2001

Use of the Pediatric Risk of Mortality Score as predictor of death and serious neurologic damage in children after submersion.

OBJECTIVE: To evaluate the Pediatric Risk of Mortality score (PRISM score) as a tool to evaluate the vital and neurologic prognosis of patients after submersion. METHODS: We conducted a retrospective analysis of the clinical histories of patients admitted to a tertiary pediatric hospital, Hospital Sant Joan de Déu, Barcelona, Spain from December 1977 to December 1999 as a consequence of near-drowning. PRISM score was calculated for each patient with data obtained upon arrival at the hospital. The probability of death was calculated using this score. RESULTS: There were 60 patients, divided into two groups as they were admitted to the Pediatric Intensive Care Unit (PICU group, n = 41) or to the Short Stay Unit (SSU group, n = 19). All patients in the SSU group survived without impairments, with PRISM scores or=24 or with probability of death >or=42% either died or had serious neurologic impairment. One third of patients with PRISM scores between 17 and 23 and/or probability of death between 16 and 42% either presented serious neurologic impairment or died. CONCLUSIONS: PRISM score enables the determination of either absence or presence of serious impairment or death in pediatric patients after submersion, if they present extreme values on this scale. However, in patients with intermediate PRISM scores, it is not possible to establish a reliable prognosis.

Adolescent↗
PubMed2000

Basicity of uranyl oxo ligands upon coordination of alkoxides.

Uranium(VI) alkoxide complexes are prepared via metathesis reactions of [UO2Cl2(THF)2]2 with potassium alkoxides in nonaqueous media. The dark red compound U[OCH2C(CH3)3]6, 1, results from redistributive exchange of oxo and neopentoxide ligands between more than one uranium species. Single-crystal X-ray diffraction analysis of 1 reveals a monomer in which the uranium is coordinated in a pseudooctahedral fashion by six neopentoxide ligands. Imposition of steric congestion at the metal center prevents oxo-alkoxide ligand exchange in the reactions using more sterically demanding alkoxides. Simple metathesis between uranyl chloride and alkoxide ligands occurs in the synthesis of golden yellow-orange UO2(OCHPh2)2(THF)2, 2, and yellow UO2[OCH(tBu)Ph]2(THF)2, 3. Single-crystal X-ray diffraction analysis of 2 reveals a monomer in which the uranium is coordinated in a pseudooctahedral fashion by two apical oxo ligands, two diphenylmethoxide ligands occupying trans positions, and two tetrahydrofuran ligands. Coordination of diisopropylmethoxide allows for synthesis of a more complex binary alkoxide system. Single-crystal X-ray diffraction analysis of watermelon red [UO2(OCH(iPr)2)2]4, 4, reveals a tetramer in which each uranium is coordinated in a pseudooctahedral fashion by two apical oxo ligands, one terminal alkoxide, two bridging alkoxide ligands, and one bridging oxo ligand from a neighboring uranyl group. These compounds are characterized by elemental analysis, 1H NMR, infrared spectroscopy, and, for 1, 2, and 4, single-crystal X-ray diffraction analysis. Luminescence spectroscopy is employed to evaluate the extent of aggregation of compounds 2-4 in various solvents. Vibrational spectroscopic measurements of 2-4 imply that, in contrast to the case of uranyl complexes prepared in aqueous environments, coordination of relatively strongly donating alkoxide ligands allows for enhancement of electron density on the uranyl groups such that the uranyl U=O bonds are weakened. Crystal data are as follows. 1: monoclinic space group C2/m, a = 10.6192(8) A, b = 18.36(1) A, c = 10.6151(8) A, beta = 109.637(1) degrees, V = 1949.1(3) A3, Z = 2, dcalc = 1.297 g cm-3. Refinement of 2065 reflections gave R1 = 0.045. 2: monoclinic space group P2(1)/c, a = 6.1796(4) A, b = 15.669(1) A, c = 16.169(1) A, beta = 95.380(1) degrees, V = 1558.7(2) A3, Z = 2, dcalc = 1.664 g cm-3. Refinement of 3048 reflections gave R1 = 0.036. 4: tetragonal space group I4, a = 17.8570(6) A, b = 17.8570(6) A, c = 11.4489(6) A, V = 3650.7(3) A3, Z = 2, dcalc = 1.821 g cm-3. Refinement of 1981 reflections gave R1 = 0.020.

Journal Article↗
PubMed2000

Influenza virus immunization effectivity in kidney transplant patients subjected to two different triple-drug therapy immunosuppression protocols: mycophenolate versus azathioprine.

BACKGROUND: Due to possible complications and treatment limitations, the prevention of influenza in renal transplant (RT) patients is highly indicated. METHODS: Forty-nine patients with a 1-year functioning RT subjected to two different immunosuppressive regimens and 37 healthy relatives (HR) were administered the anti-influenza vaccine as recommended for 1996 to 1997. Anti-influenza antibody, creatinine, and immunological markers were estimated at 1 and 3 months after vaccination. RESULTS: Three months after vaccination, 46.2% of the RT patients and 69% of the HR (P=0.06) showed protective antibody titers to influenza A (relative risk [RR]; 0.67; 95% confidence interval: 0.44-1.02). A total of 20.5% of the RT patients and 44.8% of the HR showed antibodies to influenza B (P=0.03). Despite these differences, the incidence of illness was similar. The immunosuppressive regimen had no effect on the antibody response. CONCLUSIONS: Although the RT patients showed a reduced antibody response, no negative effects on graft outcome were observed.

Adult↗
PubMed2000

Are the discrepancies between self- and others' appraisals of competence predictive or reflective of depressive symptoms in children and adolescents: a longitudinal study, Part II.

Two cohorts of children and adolescents (who started 6th grade in 1993 and 1996), parents, teachers, and peers participated in a 4-wave, 2-year, longitudinal study of perceived competence and depressive symptoms. The authors assessed children's tendencies to underestimate their competence (discrepant self-appraisals) relative to the appraisals of significant others. We also assessed the degree to which self-appraisals reflected the evaluations of others (reflective self-appraisals). Domains of competence were academic competence, physical appearance, behavioral conduct, social acceptance, and athletic competence. Cross-sectional analyses indicated that depressive symptoms correlated with reflective and discrepant self-appraisals. Longitudinal analyses revealed that reflective and discrepant self-appraisals predicted subsequent depressive symptoms and that depressive symptoms predicted discrepant but not reflective self-appraisals. Clinical implications of the findings are discussed.

Adolescent↗
PubMed2000

Sex-related differences in methionine metabolism and plasma homocysteine concentrations.

BACKGROUND: Elevated fasting homocysteine concentrations are considered a risk factor for vascular disease. Homocysteine, which is produced by the transmethylation of methionine, can be either remethylated back to methionine or metabolized via transsulfuration to cystathionine. It has been speculated that the lower risk of vascular disease among premenopausal women may be related to lower homocysteine concentrations in women than in men. OBJECTIVE: This study was designed to determine whether sex-related differences exist in methionine cycle kinetics, which may account for the reportedly lower fasting homocysteine concentrations in premenopausal women. DESIGN: Eleven healthy young men and 11 premenopausal women without cardiac risk factors were studied by using stable-isotope-labeled L-[methyl-(2)H(3),1-(13)C]methionine and L-[methyl- (2)H(3)]leucine. After 3 h of tracer infusion, 100 mg unlabeled L-methionine/kg body wt was ingested. Blood and breath samples were obtained at timed intervals. Fat-free mass was estimated by dual-energy X-ray absorptiometry and muscle mass by urinary creatinine excretion. RESULTS: No significant sex-related differences were found in fasting homocysteine concentrations, responses to the oral methionine load, or rates of methionine flux based on carboxyl or methyl labels. However, women had significantly higher remethylation rates than did men (P < 0.005) and a tendency toward higher transmethylation (P < 0.10). Whereas adjustment of remethylation rates for fat-free mass tended to attenuate the sex-related effect (P = 0.08), adjustment for muscle mass did not (P < 0.04). In contrast, significant sex-related differences in leucine flux (P < 0.02) were eliminated after adjustment for either fat-free mass or muscle mass. CONCLUSION: Reported differences between men and women in homocysteine concentrations may be partially explained by differences in rates of homocysteine remethylation.

Absorptiometry, Photon↗
PubMed2000

Treatment of shigellosis with cefixime: two days vs. five days.

BACKGROUND: Although the recommended standard course of therapy for shigellosis is 5 days of oral ampicillin or trimethoprim-sulfamethoxazole therapy, successful outcome has been reported in adults treated with abbreviated courses of antibiotics. The purpose of this study was to compare short course (2-day) vs. 5-day therapy with cefixime for treatment of diarrheal disease caused by Shigella sonnei in children. METHODS: This was a prospective, randomized, double blind, placebo-controlled study. Patients were eligible if they were at least 6 months of age and presented to the Children's Hospital of Pittsburgh during an outbreak of diarrhea caused by S. sonnei, with (1) a history of fever and diarrhea (at least three loose or watery stools per day), (2) bloody diarrhea or (3) diarrhea and known exposure to an individual with documented shigellosis. Patients were randomized to receive either 2 days of cefixime (8 mg/kg(day) given once daily followed by 3 days of placebo or 5 days of cefixime. Telephone follow-up was performed on Days 3, 7 and 14 after enrollment. Follow-up stool cultures were obtained on Day 7 to assess bacteriologic cure. There were standardized definitions for cure, improvement, failure and relapse. RESULTS: Forty-seven patients were enrolled. Eleven were eliminated from analysis because their stool cultures were not positive for S. sonnei. There were 36 evaluable patients, 21 in the 2-day group and 15 in the 5-day group. Patients ranged in age from 6 months to 17 years. Forty-four percent of the subjects were male. Symptoms were improved or had resolved by Day 3 of therapy in all patients. There were 8 patients who experienced a clinical relapse: 5 of 21 (24%) patients in the 2-day treatment group and 3 of 15 (20%) in the 5-day group. There were 13 patients who experienced a bacteriologic failure (defined as the occurrence of a positive culture at the Day 7 follow-up visit), 11 of 20 (55%) in the 2-day group and 2 of 14 (14%) in the 5-day group (P < 0.02). CONCLUSION: Two- and 5-day treatment courses with cefixime for treatment of diarrheal disease caused by S. sonnei result in similar rates of clinical cure and clinical relapses; however, there was a higher rate of bacteriologic failure with shorter course therapy.

Cefixime↗
PubMed2000

The late lytic LMP-1 protein of Epstein-Barr virus can negatively regulate LMP-1 signaling.

The BNLF-1 open reading frame of Epstein-Barr virus (EBV) encodes two related proteins, latent membrane protein-1 (LMP-1) and lytic LMP-1 (lyLMP-1). LMP-1 is a latent protein required for immortalization of human B cells by EBV, whereas lyLMP-1 is expressed during the lytic cycle and is found in the EBV virion. We show here that, in contrast to LMP-1, lyLMP-1 is stable, with a half-life of >20 h in tetradecanoyl phorbol acetate- and butyrate-treated B95-8 cells. Although lyLMP-1 itself has negligible effects on NF-kappaB activity, it inhibits NF-kappaB activation by LMP-1 in a dose-dependent manner. The lyLMP-1 protein does not oligomerize with LMP-1, and the negative effect of lyLMP-1 on NF-kappaB activation by LMP-1 does not result from lyLMP-1-mediated disruption of LMP-1 oligomers. Modulation of LMP-1-activated signaling pathways is the first identified biological activity associated with lyLMP-1, and this activity may contribute to the progression of EBV's lytic cycle.

Animals↗