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At least 541 records · Page 30Linked to original sources

PubMed2003

Dual variant of Epstein-Barr virus in Hodgkin/Reed-Sternberg cells: single-cell PCR study on latent membrane protein-1 gene.

Isolation of single cells permits analysis of DNA or RNA from individual cells among heterogeneous populations. This technique is particularly useful in the study of classical Hodgkin's lymphoma (cHL) due to the scarcity of H/RS tumor cells among large numbers of reactive leukocytes. In a previous study, we found a high frequency of dual LMP-1 variant (concurrent presence of deleted and nondeleted variants) in cHL from whole-tissue sections. For the present study, we applied a single-cell isolation technique to determine the LMP-1 oncogene variant in EBV-associated H/RS cells. Five cases of EBV-infected cHL, containing nondeleted (n=1), deleted (n=1) and dual infection (n=3) based on whole-tissue section analysis, were selected for study. Paraffin-embedded tissue sections were stained with antibody to LMP-1 and positively stained H/RS cells isolated using a semiautomated micromanipulator. Each isolated single cell was subjected to PCR for amplification of the LMP-1 gene flanking the 30 bp deletion region and Xho1 restriction site. Cases with either nondeleted variant or the deleted variant showed similar LMP-1 variant expression in isolated single H/RS cells. However, 1 of the 3 cases with dual variants showed only the deleted variant in H/RS cells. The other 2 cases showed mixed patterns of deleted, nondeleted and dual LMP-1 variants in isolated single H/RS cells. All cases showed loss of the Xho1 restriction site, with the exception of the case with nondeleted LMP-1. Results of single-H/RS cell analysis of the Xho1 restriction site concur with those of whole-tissue section amplification. A mixed pattern of LMP-1 variants was observed in isolated H/RS cells, and it is speculated that this is due to the accumulation of mutation and deletion events.

Base Sequence↗

PubMed2006

High frequency of latent membrane protein-1 30-bp deletion variant with specific single mutations in Epstein-Barr virus-associated nasopharyngeal carcinoma in Moroccan patients.

Latent membrane protein 1 (LMP-1) is an Epstein-Barr virus-encoded oncoprotein expressed in approximately 50-70% of nasopharyngeal carcinoma (NPC). Previous studies have shown that NPC-derived LMP-1 variants carrying 30 bp deletion and specific mutations in the 3'C-terminal region confer high oncogenic potential and a weak immunogenicity. Although numerous polymorphism studies of LMP-1 have been carried out so far in the Asian population with NPC, very little is known in this regard on NPC patients from Northern Africa where there is a significantly high occurrence of this tumor. In our study, we examined the frequency of different LMP-1 sequence variants derived from Moroccan NPC patients. As compared to healthy donors, NPC patients showed a high prevalence of the 30bp deletion variant of LMP-1 (i.e. 84% vs. 36%; p<0.0005). Moreover, the del-LMP-1 variant derived from NPC tumors shared identical amino acid substitutions at positions 322, 334, 338, 352 and 366 with the Mediterranean (Med) variant, whereas those derived from peripheral blood mononuclear cells (PBMC) had similar mutation pattern as China1 variant. Additional mutations within the 342-352 regions (identified in LMP-1 variants without deletion derived from NPC tumors) were not found in healthy donors' PBMC. Our results support the assumption that the distribution of LMP-1 variants in NPC tumors co-segregate with geographic regions. Indeed, Med variant is found more frequently in tumors from NPC Moroccan patients, whereas China1 variant is more prevalent in tumors from NPC patients in endemic regions for NPC.

Base Sequence↗

PubMed2003

Conservative segregation of maternally inherited CS histone variants in larval stages of sea urchin development.

Three sets of histone variants are coexisting in the embryo at larval stages of sea urchin's development: the maternally inherited cleavage stage variants (CS) expressed during the two initial cleavage divisions, the early histone variants, which are recruited into embryonic chromatin from middle cleavage stages until hatching and the late variants, that are fundamentally expressed from blastula stage onward. Since the expression of the CS histones is confined to the initial cleavage stages, these variants represent a very minor proportion of the histones present in the plutei larvae, whereas the late histone variants are predominant. To determine the position of these CS in the embryonic territories, we have immunolocalized the CS histone variants in plutei larvas harvested 72 h post-fertilization. In parallel, we have pulse labeled the DNA replicated during the initial cleavage cycle with bromodeoxyuridine (BrdU) and its position was further determined in the plutei larvas by immunofluorescence. We have found that the CS histone variants were segregated to specific territories in the plutei. The position in which the CS histone variants were found to be segregated was consistent with the position in which the DNA molecules that were replicated during the initial cleavage divisions were localized. These results strongly suggest that a specification of embryonic nuclei occurs at the initial cleavage divisions which is determined by a chromatin organized by CS histone variants.

Animals↗

PubMed2001

Prevalence and distribution of human herpesvirus 6 variants A and B in adult human brain.

The presence of human herpesvirus 6 (HHV-6) in brain tissues of 40 consecutive post-mortem cases was examined. For each case, autopsy samples were collected from the cerebellum, frontal, temporal, parietal and occipital lobes of both sides of the brain. HHV-6 DNA was detected by nested polymerase chain reaction and characterised into variants A and B. Overall, 97/400 (24.3%) samples were positive for HHV-6 DNA with 16 being variant A and 81 being variant B, but none of the samples harboured both variants. When analysed by patient, 34/40 (85%) had HHV-6 DNA detected in the brain. The viral DNA positivity did not show significant variation with gender and age. Four patients harboured variant A, 23 harboured variant B, and seven had both variants at different positions. The results indicate that both HHV-6A and HHV-6B are neurotropic and human brain may be another site for latency. HHV-6B was detected in brain tissues of a majority (75%) of the studied population and with a widespread distribution within the brain. Although the observed prevalence of HHV-6A in brain is lower (27.5%), in view of its lower seroprevalence, the neuroinvasive potential of variant A may be comparable to that of variant B. Although both variants are potential pathogens for the nervous system, the fact that they can exist, probably for most of the time, as commensals in human brain needs to be considered when interpreting their roles in neuropathology.

Adult↗

PubMed2005

Prevalence of naturally occurring surface antigen variants of hepatitis B virus in Korean patients infected chronically.

Although Korea is one of the endemic areas of hepatitis B virus (HBV) infection, the prevalence of naturally occurring variants in the major hydrophilic region (MHR) of the surface (S) gene of HBV has not been determined. In the present study, the prevalence of these variants was examined in terms of the clinical state, and HBeAg serostatus in a large series of Korean patients with chronic HBV infection by direct sequencing analysis of part of the S gene containing the MHR of HBV isolated from 101 chronic HBV patients (51 HBeAg-positive and 50 HBeAg-negative): 37 were asymptomatic carriers, 21 had chronic hepatitis, 20 had liver cirrhosis, and 23 had hepatocellular carcinoma (HCC). Forty-seven MHR variants (46.5%) of the 101 patients were detected, involving a total of 59 amino acid substitutions at 12 positions inside and 14 position outside the 'a' determinant, and 33 'a' determinant variants (32.7%). A total of 17 novel variants and 14 novel mutation patterns were detected. The prevalence of MHR variants in HBeAg-negative patients tended to be higher than in HBeAg-positive patients (54.0% vs.39.2%) and the prevalence of MHR variants in HCC and liver cirrhosis tended to be higher than in asymptomatic carriers (65.2% vs. 40.5% and 50.0% vs. 40.5%, respectively). In conclusion, three important findings were found in the present study. First, an unexpectedly high prevalence of naturally occurring MHR variants was found in Korean chronic patients. Second, several novel variants associated with mutations outside the 'a' determinant were detected. Finally, a higher prevalence of MHR variants was associated with HBeAg-negative serostatus and severe liver disease, particularly HCC.

Adolescent↗

PubMed2001

Development of a novel probe for measuring drug binding to the F1*S variant of human alpha 1-acid glycoprotein.

A novel probe was developed to measure drug association with the F1*S variant of the human serum protein alpha 1-acid glycoprotein (AGP). The molecule 2-hydroxy-3,5-diiodo-N-[2(diethylamino)ethyl]benzamide (DEDIC) binds to AGP, quenching its native fluorescence. This quenching was fitted to a two-site model giving apparent dissociation constants of 0.049 +/- 0.005 and 12 +/- 2 microM (mean +/- SEM). Quenching of each of the separate variants of AGP by DEDIC was itself described by a two-site model, giving for the F1*S variant K(D)(1)((F1*S)) = 0.041 +/- 0.010 microM and K(D)(2)((F1*S)) = 29 +/- 7 microM; and for the A variant K(D)(1)((A)) = 0.31 +/- 0.18 microM and K(D)(2)((A)) = 8.8 +/- 0.7 microM. The utility of DEDIC in probing drug interactions with isolated variants was demonstrated in competition experiments with the model drugs amitriptyline and bupivacaine. In addition, the selectivity of DEDIC for variant F1*S rendered it capable of probing the binding of drugs (including the variant A-selective drug amitriptyline) to F1*S in a mixture of variants, such as occurs naturally in whole AGP. DEDIC is unique as an F1*S variant-selective probe of drug binding to whole AGP that is also sufficiently soluble to serve as a probe of drug binding to the lower affinity sites on isolated A and F1*S variants.

Anesthetics, Local↗

PubMed1997

Major sequence variants in E7 gene of human papillomavirus type 16 from cervical cancerous and noncancerous lesions of Korean women.

Geographic specificity of nucleotide sequence variations in the coding and noncoding regions of HPV 16 genome has been reported. Little has been known, however, regarding whether these naturally occurring sequence variations of HPV 16 may result in marked differences in biological properties, such as oncogenic potential. This study was performed to identify sequence variants in the HPV 16 E7 gene derived from Korean women with cervical cancerous and noncancerous lesions, and to assess the association between the sequence variant and the cervical cancer. We examined E7 variants of HPV 16 in a total of 157 patients with no cervical disease (NCD, n = 87) or cervical neoplasia (cervical intraepithelial neoplasia 3, n = 21; cervical carcinoma, n = 49), using the nested polymerase chain reaction (PCR) and the PCR-directed sequencing methods with outer consensus and inner type-specific primers. Forty-two (NCD, n = 9; CIN 3, n = 6; cervical carcinoma, n = 27) of 157 cervical samples contained HPV 16 E7 DNA, but only 8 had prototype sequences. Four variants of the HPV 16 E7 gene were identified. The variant with a single nucleotide change at position 647 (A --> G, Asn --> Ser) was found in about 60% of DNA samples with HPV 16. The second most common variant, found in 16.7% of cases, had three silent mutations at positions 732 (T --> C), 789 (T --> C), and 795 (T --> G). Two other variants were detected, one in a patient with cervical cancer and the other in a patient with no cervical disease. One had a single nucleotide change at position 666 (G --> A) and the other had one silent mutation at position 796 (T --> C). The most common variant in Korea has a change of nucleotide affecting the predicted amino acid related with high antigenicity and binding to retinoblastoma protein. There was a statistically significant trend for this variant to be more frequently detected in cancerous lesions of the uterine cervix than in noncancerous lesions. These data suggest that naturally occurring sequence variants of HPV 16 E7 gene may have different oncogenic properties.

Adult↗

PubMed1999

Expression of estrogen receptor alpha mRNA and protein variants in human endometrial carcinoma.

Breast cancer tissue has been shown to contain alternatively spliced estrogen receptor alpha (ER-alpha) mRNA variants, which have altered biological activities compared to the full-length ER-alpha. The development of endometrial cancer, as well as drug resistance in breast cancer patients undergoing tamoxifen therapy, may represent altered ER-alpha function secondary to specific exon deletions. While the literature is replete with ER mRNA variant data, little information is available regarding the presence and function of endometrial ER variant proteins. We evaluated the presence of human ER-alpha mRNA and protein variants in six premenopausal, six postmenopausal, and six endometrial carcinoma samples. Reverse transcription-polymerase chain reaction, DNA hybridization, and sequencing techniques identified exon 4, exon 5, and exon 7 mRNA splice variants in all patients as well as MCF-7 and Ishikawa cell lines. Presence of translated proteins for full-length ER-alpha, as well as splice variants, was investigated by Western blot analysis using antibodies directed against the N-terminus, hinge region, and C-terminus portions of the ER. These experiments confirmed the presence of immunopositive protein bands of approximately 64-66 kDa in all patients corresponding to wild-type ER-alpha. A protein band migrating at 41 kDa, consistent with an exon 5 splice variant, was only seen in endometrial adenocarcinoma samples. Premenopausal and postmenopausal endometrial samples did not contain detectable amounts of ER splice variant protein. Human ER-alpha mRNA variants are present in all human endometrial samples, but detectable levels of variant proteins are only observed in patients with endometrial adenocarcinoma.

DNA, Neoplasm↗

PubMed1994

Two different IFN-gamma nonresponsive variants derived from the B-cell lymphoma 70Z/3.

The kappa immunoglobulin (Igk) light chain locus is transcriptionally silent in the mouse B-cell lymphoma 70Z/3. However, exposure to lipopolysaccharide (LPS) or interferon-gamma (IFN) causes a marked increase in Igk transcription. By immunoselection, we isolated two variants that are nonresponsive to IFN. One variant, AT7.2, has retained its response to LPS (IFN-LPS+), whereas the other, AT3.3, is also nonresponsive to LPS (IFN-LPS-). Stable transfection of an intact Igk gene does not rescue the phenotype of either variant. Both variants have intact Igk genes and neither is deficient in the binding or uptake of IFN. Nuclear extracts from LPS-treated wild-type 70Z/3 cells show strong increases in three transcription factors: OTF-2, NF-kappa B, and kBF-A. Remarkably, when the IFN-LPS- variant is treated with LPS, all three transcription factors are still observed in the nuclear extracts. Treatment of wild-type cells with either LPS or IFN also causes a decrease in nuclear complexes that bind to two other regions of the Igk intron enhancer, the octenh and the E kappa MHCIC regions. Both of these changes are also observed after LPS or IFN treatment of the IFN-LPS- variant. Thus, this variant transduces the IFN and LPS signals at least into the nuclear compartment, but still fails to activate Igk transcription. In contrast, the IFN-LPS+ variant decreases neither the octenh nor the E kappa MHCIC binding complexes in response to IFN. This variant may be defective in transducing the IFN signal to the nucleus. These variants will be useful in studying the activation of Igk transcription and the IFN signaling pathway in B cells.

Animals↗

PubMed1995

Detachment of transformed cells. Role of CD44 variants.

A parallel-plate flow chamber was used to quantify the detachment of normal cloned rat embryo fibroblasts (CREF) fibroblasts, ras-transformed CREF fibroblasts (CREF T24), and CREF T24 fibroblasts transfected with a Krev/RAP1A suppressor gene (HK B1) from a confluent monolayer of normal CREF fibroblasts to determine if the expression patterns of CD44 variants (mol wt 110 and 140 kDa) corresponded with detachment properties and metastatic potential. In the detachment assay, known shear stresses ranging from 20-24 dyn/cm2 were applied to the adherent cells and the number of cells detached from the monolayer after 180 s was determined. Results showed that cellular expression of CD44 variants correlated with the metastatic potential of the cells and with the cells' ability to detach from a monolayer of normal cells. Western blot analysis showed a low level of expression of the CD44 variants in the normal cell line, CREF, and the lowly metastatic cell line, HK B1. Detachment studies showed a low percentage of detachment of both of these cell lines from a normal cell monolayer. Tumor-derived (HK B1-T) and lung nodule-derived (HK B1-M) cell lines were established and both formed tumors and metastasis with reduced latency periods as compared to HK B1, but still showed a markedly delayed latency period compared to the highly metastatic cell line, CREF T24. Both of these cell lines showed a higher expression of the CD44 variants as compared to CREF and HK B1, and detached easier than CREF and HK B1. CREF T24 showed a much higher level of expression of the variants and had a higher percentage detachment than all other cell lines. To further test the role of the CD44 variants in the ability of the cells to detach from the normal monolayer, CREF cells were transfected with a DNA construct that constitutively expresses the CD44 variants and the detachment properties of three randomly selected clones were studied. Clones 2 and 3 showed a low level of expression of the CD44 variants after transfection and detached from the normal monolayer similar to CREF. Clone 1 showed a high level of expression of the CD44 variants and the detachment of these cells was significantly higher than CREF. From these results, it is concluded that in the five cell lines studied, expression of the CD44 variants play a significant role in the ability of the cells to detach from a monolayer of normal cells. It is hypothesized that this detachment may be an important component of a cell's ability to metastasize.

Animals↗

PubMed2005

Novel sequence variants in the TMIE gene in families with autosomal recessive nonsyndromic hearing impairment.

To date, 37 genes have been identified for nonsyndromic hearing impairment (NSHI). Identifying the functional sequence variants within these genes and knowing their population-specific frequencies is of public health value, in particular for genetic screening for NSHI. To determine putatively functional sequence variants in the transmembrane inner ear (TMIE) gene in Pakistani and Jordanian families with autosomal recessive (AR) NSHI, four Jordanian and 168 Pakistani families with ARNSHI that is not due to GJB2 (CX26) were submitted to a genome scan. Two-point and multipoint parametric linkage analyses were performed, and families with logarithmic odds (LOD) scores of 1.0 or greater within the TMIE region underwent further DNA sequencing. The evolutionary conservation and location in predicted protein domains of amino acid residues where sequence variants occurred were studied to elucidate the possible effects of these sequence variants on function. Of seven families that were screened for TMIE, putatively functional sequence variants were found to segregate with hearing impairment in four families but were not seen in not less than 110 ethnically matched control chromosomes. The previously reported c.241C>T (p.R81C) variant was observed in two Pakistani families. Two novel variants, c.92A>G (p.E31G) and the splice site mutation c.212 -2A>C, were identified in one Pakistani and one Jordanian family, respectively. The c.92A>G (p.E31G) variant occurred at a residue that is conserved in the mouse and is predicted to be extracellular. Conservation and potential functionality of previously published mutations were also examined. The prevalence of functional TMIE variants in Pakistani families is 1.7% [95% confidence interval (CI) 0.3-4.8]. Further studies on the spectrum, prevalence rates, and functional effect of sequence variants in the TMIE gene in other populations should demonstrate the true importance of this gene as a cause of hearing impairment.

Connexin 26↗

PubMed1987

Reduced mouse neurovirulence of poliovirus type 2 Lansing antigenic variants selected with monoclonal antibodies.

The Lansing strain of poliovirus type 2 is a mouse-adapted virus that induces a fatal paralytic disease in mice after intracerebral inoculation. Our previous results indicated that the mouse-adapted phenotype maps to the Lansing viral capsid. To further define regions of the capsid that are specifically involved in the infection of mice, antigenic variants resistant to neutralization with monoclonal antibodies were selected, and their mouse neurovirulence was studied. The monoclonal antibodies used were directed against antigenic site 1, an immunodominant loop of capsid polypeptide VP1 located on the virion surface. Ten of twenty-two variants selected had lower intracerebral neurovirulence in mice when compared to the parental virus. Four of the ten antigenic variants with reduced neurovirulence were temperature sensitive (ts) for replication in HeLa cells, while the remaining six variants replicated in HeLa cells as well as the parent virus. Two ts+ variants that were studied had a reduced ability to replicate in the mouse brain. There was no difference in the histopathology and pattern of involvement in the central nervous system of one variant compared to the parent virus. In three variants, reduction of neurovirulence correlated with specific amino acid substitutions at positions 100 and 101 of VP1, located within antigenic site 1. The ts phenotype in three variants was associated with a single amino acid deletion at position 105. Virus recovered from the brain of paralyzed mice that had been inoculated with the antigenic variants was characterized to identify the virus causing disease. In most cases, brain isolates resembled the inoculated virus in neurovirulence and amino acid sequence at the antigenic site. Virus recovered from brains of paralyzed mice that had been inoculated with the ts variants was either ts+ or cold sensitive, and had become more neurovirulent. These results suggest that specific amino acid changes within an antigenic site on the virion surface may result in reduction of mouse neurovirulence without affecting viral replication in cultured cells.

Animals↗

PubMed1989

Biological and immunological characterization of a simian rotavirus SA11 variant with an altered genome segment 4.

We have studied a variant virus isolated from a stock of SA11 virus (H. G. Pereira, R. S. Azeredo, A. M. Fialho, and M. N. P. Vidal, 1984, J. Gen. Virol. 65, 815-818). This virus, designated 4F, was initially identified by its faster electrophoretic mobility for genome segment 4. The variant was analyzed to determine if the altered electrophoretic mobility of genome segment 4 could be correlated with phenotypic changes. Comparison of our standard laboratory SA11 virus (clone 3) with the 4F variant showed the following: (i) The 4F variant possesses a viral hemagglutinin (VP4) with a higher apparent molecular weight than clone 3. (ii) The 4F variant produces large plaques when assayed in vitro, as compared to clone 3. (iii) The 4F variant produces plaques in the absence of proteolytic enzymes, whereas clone 3 does not. (iv) The 4F variant reacts with serotype-specific neutralizing monoclonal antibodies to VP7, but fails to react with several neutralizing anti-VP4 monoclonal antibodies generated to SA11 clone 3. (v) The 4F variant grows to a higher titer and is more stable than clone 3. (vi) The 4F variant produces a VP4 that appears to be more susceptible to cleavage by trypsin than is the VP4 of clone 3. Further analyses with the 4F variant may lead to an understanding of the molecular basis for these altered phenotypes that appear to be related, at least in part, to the product of genome segment 4.

Antigens, Viral↗

PubMed1989

Humoral immune response elicited by highly attenuated variants of vaccinia virus and by an attenuated recombinant expressing HIV-1 envelope protein.

Attenuated variants of vaccinia virus have excellent potential for the construction of safe recombinant live vaccines. In this investigation, highly attenuated variants of vaccinia virus with several genetic markers and a variant recombinant were tested in Balb/c mice for their ability to induce humoral immune response. Mice primed with variants that had an 8-MDa deletion at the left end of the viral genome induced similar levels of circulating anti-vaccinia antibodies as the wild-type virus. However, mice primed with variants that had several genetic lesions (deletions and point mutations) induced lower levels of circulating anti-vaccinia antibodies. Mice primed and boosted with a recombinant variant with several genetic lesions, and containing the complete envelope gene of the human immunodeficiency virus (HIV) and the bacterial beta-galactosidase (beta-gal) gene, induced significant antibody response to gp 160 and beta-gal. The antibody response to gp 160 was markedly increased by successive inoculations with the recombinant variant. Our findings provide evidence that the extent of activation of the immune system by vaccinia variants can be modulated by the nature of the virus genetic lesion. In addition, when these variants are used as recombinant vaccines, it is possible to induce low levels of circulating anti-vaccinia antibodies after priming and yet achieve significant antibody response to virus-expressed foreign antigens, even after repeated boosters. Such variants could be useful in the design of live recombinant viruses as safe vaccines.

Animals↗

PubMed1984

The incidence, type, and subsequent evolution of 14 variant Ph1 translocations in 180 South African patients with Ph1-positive chronic myeloid leukemia.

A Philadelphia (Ph1) chromosome translocation was found in 180 of 198 cases of chronic myeloid leukemia (CML). A standard t(9;22) was present in 166 patients, 83 of whom were black, 79 white, and 4 of "mixed" ancestry; whereas a variant Ph1 translocation was detected in 14 patients (7.8%), 11 of whom were black and only 3 white. There was a higher frequency of a variant Ph1 among black patients compared with whites. The significantly higher frequency of a variant among our patients compared with surveys from elsewhere could be due to differing environmental agents. Simple variants were detected in four patients. Complex variants were found in eight cases; in one of these patients, only chromosomes #9 and #22 were involved, but a complex rearrangement of chromosome #9 had occurred. A "masked" Ph1 translocation was detected in two cases, both of which showed monosomy #22 because the Ph1 chromosome was incorporated or interchanged with chromosome #9. Karyotypic evolution of the Ph1-positive cell line was observed more frequently in the variant group (71.4%) than the standard group (29.5%). This difference was significant (p less than 0.005). There was no difference in the type of clonal changes seen in standard and variant groups. The majority of clonal changes were observed during the acute stage in both groups. In the variant group, there was no obvious correlation between the type of variant, type of clonal change, blast morphology, or survival. Their initial survival pattern resembled that of Ph1-negative cases, but those patients who survived longer than 1 year showed a survival trend similar to standard Ph1-positive cases. Possible explanations for the specificity of chromosome #22 involvement and the constancy of the 22q11 breakpoint in all these variant translocations are discussed.

Adult↗

PubMed1994

Consistent occurrence of hemagglutinin variants among avian influenza virus isolates of the H7 subtype.

Several field isolates of avian influenza virus of the H7 subtype were analyzed for the presence of hemagglutinin variants by labeling proteins in cells infected with virus clones, and reacting with monoclonal antibodies. Each strain was shown to contain two distinct electrophoretic variants of the uncleaved hemagglutinin. In the A/Tk/Ore/71 (H7N3) isolate, two variants remained in the population through 35 laboratory passages, indicating both are stable and may be important to expression of the viral phenotype. Nucleotide sequence analysis of the HA gene of these two variants demonstrated differences at several amino acid positions in the HA1 subunit including one glycosylation site. Three additional recent North American isolates were also each found to contain two electrophoretic variants occurring within populations as few as one embryo passage away from the original clinical specimen. Pulse-chase assays indicated none of the variant HA molecules were cleavable in chick embryo fibroblasts. In the highly pathogenic Australian isolate; A/Ck/Victoria/75, both HA variants are cleavable in fibroblasts, without added trypsin, and the differences are localized within the HA1 region. With all the strains tested, the slower migrating HA variant was associated with a consistently higher hemagglutinin titer in embryos. Finally, recent H7 isolates from imported birds (A/Soft Bill/Ill/92) also exhibit similar variants, indicating their occurrence is not limited to domestic poultry. This consistent presence of two distinct electrophoretic variants in several avian H7 isolates suggests multiple allelic forms of the H7 hemagglutinin.

Animals↗

PubMed2004

Gene variants and binge eating as predictors of comorbidity and outcome of treatment in severe obesity.

Melanocortin-4 receptor gene (MC4R) variants are associated with obesity and binge eating disorder (BED), whereas the more prevalent proopiomelanocortin (POMC) and leptin receptor gene (LEPR) mutations are rarely associated with obesity or BED. The complete coding regions of MC4R, POMC, and leptin-binding domain of LEPR were comparatively sequenced in 300 patients (233 women and 67 men; mean +/- SEM age, 42 +/- 1 years; mean +/- SEM body mass index, 43.5 +/- 0.3 kg/m2) undergoing laparoscopic gastric banding. Eating behavior, esophagogastric pathology, metabolic syndrome prevalence, and postoperative weight loss and complications were retrospectively compared between carriers and noncarriers of gene variants with and without BED during 36 +/- 3-month follow-up. Nineteen patients (6.3%) carried 8 MC4R variants, 144 (48.0%) carried 13 POMC variants, and 247 (82.3%) carried 11 LEPR variants. All MC4R variant carriers had BED, compared with 18.1% of noncarriers (P < 0.001). BED rates were similar among POMC and LEPR variant carriers and noncarriers. Gastroscopy revealed more erosive esophagitis in bingers than in nonbingers before and after banding (P < 0.04), regardless of genotype. MC4R variant carriers lost less weight (P=0.003), showed less improvement in metabolic syndrome (P < 0.001), had dilated esophagi (P < 0.001) and more vomiting (P < 0.05), and had fivefold more gastric complications (P < 0.001) than noncarriers. Overall outcome was poorest in MC4R variant carriers, better in noncarriers with BED (P < 0.05), and best in noncarriers without BED (P < 0.001). MC4R variants influence comorbidities and treatment outcomes in severe obesity.

Adult↗

PubMed2006

Identification of novel splice variants of Adhesion G protein-coupled receptors.

Alternative splicing is an important mechanism to generate proteome diversity in higher eukaryotic organisms. We searched for splice variants of the human Adhesion family of G protein-coupled receptors (GPCRs) using mRNA sequences and expressed sequence tags. The results presented here describe 53 human splice variants among the 33 Adhesion GPCRs. Many of these variants appear to be coding for "functional" proteins (29) while the others are seemingly "non-functional" (24). Novel functional splice variants were found for: CD97, CELR3, EMR2, EMR3, GPR56, GPR110, GPR112-GPR114, GPR116, GPR123-GPR126, GPR133, HE6, and LEC1-LEC3. Splice variants for GPR116, GPR125, GPR126, and HE6 were found conserved in other species. Several of the functional splice variants lack one or more of the functional domains that are found in the N-termini of these receptors. These functional domains are likely to affect ligand binding or interaction with other proteins and these novel splice variants may have important roles for the specificity of interactions between these receptors and extracellular molecules. Another type of splice variants found here lacks a GPCR proteolytic site (GPS). The GPS domain has been shown to be essential for the proteolytic cleavage of the receptors N-termini and for cellular surface expression. We suggest that these alternative splice variants may be crucial for the function of the receptors while the seemingly non-functional splice variants may be a part of a regulative mechanism.

Alternative Splicing↗