Biomedical subjects

L Liu

Publications and source records attributed to L Liu.

At least 739 records · Page 41Linked to original sources

PubMed1997

Transformation of sensory signals into commands for saccadic eye movements: a neural network study.

A biological plausible neural network which simulated the input-output transformation performed by primates during saccadic eye movements is constructed using a selective attention module and multi-layered neural networks with improved back propagation and a competitive learning algorithm. Simulation results show that the trained model can make fine saccades directed by the target. Representations and processing mechanisms in the saccade system are investigated. The features of most hidden units resemble those that have been observed in physiological recordings of neurons in primates visual cortex. The hidden layer even developed structures similar to those of area 7a.

Algorithms↗

PubMed1997

CDKN2A mutation in a non-FAMMM kindred with cancers at multiple sites results in a functionally abnormal protein.

The CDKN2A gene encodes p16 (CDKN2A), a cell-cycle inhibitor protein which prevents inappropriate cell cycling and, hence, proliferation. Germ-line mutations in CDKN2A predispose to the familial atypical multiple-mole melanoma (FAMMM) syndrome but also have been seen in rare families in which only 1 or 2 individuals are affected by cutaneous malignant melanoma (CMM). We therefore sequenced exons 1alpha and 2 of CDKN2A using lymphocyte DNA isolated from index cases from 67 families with cancers at multiple sites, where the patterns of cancer did not resemble those attributable to known genes such as hMLH1, hMLH2, BRCA1, BRCA2, TP53 or other cancer susceptibility genes. We found one mutation, a mis-sense mutation resulting in a methionine to isoleucine change at codon 53 (M531) of exon 2. The individual tested had developed 2 CMMs but had no dysplastic nevi and lacked a family history of dysplastic nevi or CMM. Other family members had been diagnosed with oral cancer (2 persons), bladder cancer (1 person) and possibly gall-bladder cancer. While this mutation has been reported in Australian and North American melanoma kindreds, we did not observe it in 618 chromosomes from Scottish and Canadian controls. Functional studies revealed that the CDKN2A variant carrying the M531 change was unable to bind effectively to CDK4, showing that this mutation is of pathological significance. Our results have confirmed that CDKN2A mutations are not limited to FAMMM kindreds but also demonstrate that multi-site cancer families without melanoma are very unlikely to contain CDKN2A mutations.

Adolescent↗

PubMed1997

O6-methylguanine-DNA methyltransferase (MGMT) transfectants of a 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)-sensitive colon cancer cell line selectively repopulate heterogenous MGMT+/MGMT- xenografts after BCNU and O6-benzylguanine plus BCNU.

To evaluate the role of O6-alkylguanine-DNA alkyltransferase (AGT) in colon tumor chloroethylnitrosourea (CENU) resistance, AGT-deficient VACO 8 cells were transfected with a vector containing or lacking the human O6-methylguanine-DNA methyltransferase (MGMT) cDNA. VACO 8MGMT (V8MGMT) sublines possessed high levels of AGT activity in cell culture and were > 10-fold resistant to the CENU 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). V8MGMT cells, VACO 8neo cells, and mixtures of both were grown as xenografts in nude mice. MGMT expression in VACO 8 xenografts reflected the percentage of V8MGMT cells present in the tumor inoculum. Xenografts originally containing 0-10% V8MGMT cells were sensitive to BCNU, although partial resistance was observed as the percentage of V8MGMT cells increased. Tumors containing 30-100% V8MGMT cells were completely resistant to BCNU with no regressions and no growth delays. Pretreatment with O6-benzylguanine (BG) depleted tumor AGT activity for at least 6 h and sensitized xenografts containing 1 and 100% V8MGMT cells to BCNU. After BCNU or BG + BCNU, xenografts growing from inoculums containing as low as 0.1% V8MGMT cells had high AGT activities similar to that found in V8MGMT xenografts, with the majority of the cells expressing MGMT. These results provide evidence that MGMT expression influences both intrinsic and acquired colon tumor CENU resistance, that selective expansion of AGT+ colon tumor cells commonly occurs after CENU exposure, and that BG is effective in sensitizing colon tumors to CENUs, even when only a small fraction of the cells in a heterogeneous tumor express MGMT.

Animals↗

PubMed1997

Concurrent platinum-based chemotherapy and hyperfractionated radiotherapy with late intensification in advanced head and neck cancer.

PURPOSE: To determine whether a course of hyperfractionated radiation therapy concomitant with escalated radiosensitizing platinum compounds can be administered with acceptable morbidity and achieve a high rate of loco-regional control for Stage III and IV head and neck cancer and whether the patients can be tumor free at the primary site after initial therapy and cured by the additional chemoradiation without radical resection of the primary tumor. METHODS AND MATERIALS: Patients with Stage III/IV head and neck cancer were treated in this multicenter Phase II Study with 1.8 Gy fraction radiotherapy for 2 weeks, with escalation to 1.2 Gy b.i.d. hyperfractionation to 46.8 Gy. Concomitant continuous infusion cisplantinum (CDDP) 20 mg per meter square on day 1 to 4 and 22 to 25 was given. Reassessment by biopsy of primary and nodes was done. Patients with a complete response continued with hyperfractionated radiotherapy to 75.6 Gy with simultaneous carboplatinum (Carbo), 25 mg per meter square b.i.d. for 12 consecutive treatment days. Patients with residual disease at 46.8 Gy required curative surgery. Seventy-four patients were treated at the three institutions; 20 were Stage III and 54 were Stage IV. All patients had daily mouth care, nutritional, and psychosocial support. RESULTS: This regime was well tolerated. Eighty-five percent of toxicities were Grade 1 or 2 and there was only one Grade 4 hematologic toxicity. Late toxicities included xerostomia in 25 patients, dysphasia in 18, and mild speech impediment in 11. Biopsies of primary site were done after the first course of treatment in 59 patients. Neck dissections were performed in 35 patients. Forty-four of 59 (75%) primary sites and 16 of 35 (46%) lymph nodes had pathologically complete response (CR). Of the 74 patients, only 12 required surgical resection of the primary site. Thirty-five of the 50 node positive patients had neck dissections, 16 of these were CRs at surgery. At 4 years (median follow-up of 26 months), disease-specific survival is 63%. The actuarial survival for all patients is 51%. Patients with pathological CR after initial treatment have disease specific survival of 73% at 4 years vs. 48% of patients with partial response (PR) only. CONCLUSION: This study, developed on the basis of radiobiological and cell kinetic precepts, produced results that compare favorably with other reports of management of patients with advanced head and neck cancer. In comparison with our previous study, these results are comparable, not impressively better. The associated morbidity was somewhat worse.

Adult↗

PubMed1997

Integrins (alpha7beta1) in muscle function and survival. Disrupted expression in merosin-deficient congenital muscular dystrophy.

Mutations in genes coding for dystrophin, for alpha, beta, gamma, and delta-sarcoglycans, or for the alpha2 chain of the basement membrane component merosin (laminin-2/4) cause various forms of muscular dystrophy. Analyses of integrins showed an abnormal expression and localization of alpha7beta1 isoforms in myofibers of merosin-deficient human patients and mice, but not in dystrophin-deficient or sarcoglycan-deficient humans and animals. It was shown previously that skeletal muscle fibers require merosin for survival and function (Vachon, P.H., F. Loechel, H. Xu, U.M. Wewer, and E. Engvall. 1996. J. Cell Biol. 134:1483-1497). Correction of merosin deficiency in vitro through cell transfection with the merosin alpha2 chain restored the normal localization of alpha7beta1D integrins as well as myotube survival. Overexpression of the apoptosis-suppressing molecule Bcl-2 also promoted the survival of merosin-deficient myotubes, but did not restore a normal expression of alpha7beta1D integrins. Blocking of beta1 integrins in normal myotubes induced apoptosis and severely reduced their survival. These findings (a) identify alpha7beta1D integrins as the de facto receptors for merosin in skeletal muscle; (b) indicate a merosin dependence for the accurate expression and membrane localization of alpha7beta1D integrins in myofibers; (c) provide a molecular basis for the critical role of merosin in myofiber survival; and (d) add new insights to the pathogenesis of neuromuscular disorders.

Animals↗

PubMed1997

Suppression of tumor necrosis factor-induced cell death by inhibitor of apoptosis c-IAP2 is under NF-kappaB control.

Members of the NF-kappaB/Rel and inhibitor of apoptosis (IAP) protein families have been implicated in signal transduction programs that prevent cell death elicited by the cytokine tumor necrosis factor alpha (TNF). Although NF-kappaB appears to stimulate the expression of specific protective genes, neither the identities of these genes nor the precise role of IAP proteins in this anti-apoptotic process are known. We demonstrate here that NF-kappaB is required for TNF-mediated induction of the gene encoding human c-IAP2. When overexpressed in mammalian cells, c-IAP2 activates NF-kappaB and suppresses TNF cytotoxicity. Both of these c-IAP2 activities are blocked in vivo by coexpressing a dominant form of IkappaB that is resistant to TNF-induced degradation. In contrast to wild-type c-IAP2, a mutant lacking the C-terminal RING domain inhibits NF-kappaB induction by TNF and enhances TNF killing. These findings suggest that c-IAP2 is critically involved in TNF signaling and exerts positive feedback control on NF-kappaB via an IkappaB targeting mechanism. Functional coupling of NF-kappaB and c-IAP2 during the TNF response may provide a signal amplification loop that promotes cell survival rather than death.

Apoptosis↗

PubMed1997

A neurohormone regulating both methyl farnesoate synthesis and glucose metabolism in a crustacean.

Methyl farnesoate (MF) has been identified as a juvenile hormone-like compound in crustacea which has central roles in the regulation of development and reproduction. To study the regulation of MF synthesis, we isolated a neuropeptide which inhibits MF synthesis from the neurohemal organ-sinus gland X-organ complex of the spider crab Libinia emarginata. The primary structure of this neuropeptide has been determined. It has 72 amino acid residues (deduced molecular mass 8490.5 Da) with pyroglutamic acid at the N-terminus and NH3 at the C-terminus. It shares a high percentage of sequence identity with other sinus gland neuropeptids which form the unique family of CHH neuropeptides of crustacea. Activity studies showed that this neurohormone has dual effects: it inhibited MF synthesis in vitro and had hyperglycemic activity when injected into crabs.

Amino Acid Sequence↗

PubMed1997

Elevated expression of eIF4E and FGF-2 isoforms during vascularization of breast carcinomas.

The translation initiation factor eIF4E is a novel protooncogene found over expressed in most breast carcinomas (Kerekatte et al., 1995), but the pathology where this elevation is initially manifested and its possible role in cancer progression are unknown. We report that eIF4E is markedly increased in vascularized malignant ductules of invasive carcinomas, whereas necrotic and avascular ductal carcinomas in situ display significantly lower levels. eIF4E facilitates the synthesis of FGF-2, a powerful tumor angiogenic factor. Conversely, reducing eIF4E with antisense RNA in MDA-435 cells suppresses their tumorigenic and angiogenic properties, consistent with loss of FGF-2 synthesis. These findings suggest a causal role for eIF4E in tumor vascularization.

Animals↗

PubMed1997

The human beta-defensin-1 and alpha-defensins are encoded by adjacent genes: two peptide families with differing disulfide topology share a common ancestry.

We cloned a novel human beta-defensin gene and determined its full-length cDNA sequence. The entire gene spanned more than 7 kb and included a large 6962-bp intron. The 362-bp cDNA encoded a prepropeptide that corresponded precisely to the recently identified human beta-defensin HBD-1, an antimicrobial peptide implicated in the resistance of epithelial surfaces to microbial colonization. By two-color fluorescence in situ hybridization on both metaphase chromosome and released chromatin fiber, HBD-1 gene (DEFB1 in HUGO/GDB nomenclature) mapped to chromosomal region 8p23.1-p23.2 in close proximity (within 100-150 kb) to the gene for the human neutrophil alpha-defensin HNP-1 (DEFA1). Thus, despite a complete lack of DNA sequence similarity and despite differences in their disulfide-pairing pattern, the alpha- and beta-families appear to have evolved from a common premammalian defensin gene.

Algorithms↗

PubMed1997

Overexpression of Bcl-X(L) inhibits Ara-C-induced mitochondrial loss of cytochrome c and other perturbations that activate the molecular cascade of apoptosis.

High-dose Ara-C (HIDAC) induces the cleavage and activity of caspase-3 (CPP32beta/Yama/apopain), resulting in the morphological and biochemical features of apoptosis. High levels of the antiapoptotic Bcl-x(L) or Bcl-2, relative to the proapoptotic Bax, have been shown to inhibit HIDAC-induced cleavage and activity of caspase-3 and apoptosis of the human acute myeloid leukemia HL-60 cells. In a previous report, we demonstrated this inhibition, using the control HL-60 (HL-60/neo) cells and their counterparts, HL-60/Bcl-x(L), which have enforced overexpression of Bcl-x(L) and a significantly lower ratio of free to bound Bax. Results of the present studies demonstrate that, in the initiation phase of apoptosis of HL-60/neo cells due to HIDAC (10 or 100 microM for 4 h), cytochrome c is released from the mitochondria to the cytosol, followed by the loss of mitochondrial membrane potential (deltapsi m) and an increase in the reactive oxygen species; these events precede and trigger the cleavage and activity of caspase-3. These HIDAC-induced early mitochondrial and cytosolic perturbations, which represent the initiation phase of HIDAC-induced apoptosis, were inhibited in HL-60/Bcl-x(L) cells. HIDAC treatment for 4 h also modestly increased the intracellular levels of free Bax relative to Bax bound to Bcl-2 and Bcl-x(L) in HL-60/neo but not in HL-60/Bcl-x(L) cells. In HL-60/neo cells, HIDAC-induced progressive accumulation of cytochrome c in the cytosol, the decrease in deltapsi m, and the increase in reactive oxygen species were not inhibited by coculture with the tetrapeptide inhibitors of caspases that have been previously shown to inhibit Ara-C-induced cleavage and activity of caspase-3 and apoptosis. These findings indicate that Bcl-x(L) inhibits HIDAC-induced preapoptotic mitochondrial perturbations, which prevent the accumulation of cytochrome c in the cytosol, thereby preserving caspase-3 in the inactive zymogen state and checking the molecular cascade of apoptosis.

Apoptosis↗

PubMed1997

Detection of the proto-oncogene eIF4E in surgical margins may predict recurrence in head and neck cancer.

Head and neck squamous cell cancers (HNSCC) have a high local recurrence rate due to incomplete tumor resection. The use of molecular markers to establish surgical margins may decrease local recurrence. Surgical margins are determined by histopathologic analysis on frozen sections. We postulate that genetic and molecular changes precede gross histologic alterations. Tumor markers may improve the reliability of pathology examination, but those evaluated to date lack the sensitivity needed for routine clinical use. Western blot analysis showed elevated eIF4E in all 26 HNSCC in contrast to its low expression in benign lesions. Surgical margins were analysed for eIF4E in 23 patients. Twelve patients showed elevated eIF4E in histologically negative margins. Cancer has recurred in 5 of the 12 patients as opposed to none of the 11 patients with eIF4E negative margins (P= 0.02, Log rank test). This is the first report of eIF4E in HNSCC, as a sensitive and specific marker for HNSCC, with potential for defining clear resection margins. The correlation between elevated levels of eIF4E at the margins and recurrence highlights its ability to detect malignant cells prior to clear-cut alterations in morphology. The accuracy and simplicity of these assays underscore the usefulness of eIF4E in managing HNSCC.

Aged↗

PubMed1997

Use of a polybrene capillary coating in capillary electrophoresis for rapid analysis of hemoglobin variants with on-line detection via an ion trap storage/reflectron time-of-flight mass spectrometer.

A polybrene capillary coating in capillary electrophoresis (CE) has been used for rapid analysis of hemoglobin variant digests. The use of the polybrene capillary coating has allowed sufficient separation to resolve the large number of digest products formed upon tryptic digestion of the whole protein, so that prior separation of the hemoglobin alpha and beta chains is not required. The resolution of the digest peaks obtained by CE is sufficient so that even single amino acid substitutions can easily be detected using UV absorption detection. The digest is further analyzed by capillary electrophoresis separation with on-line detection using electrospray ionization interfaced to the ion trap storage/reflectron time of flight device (CE/ESI-IT/reTOF), where a comparison of the total ion electropherograms and mass spectra of the mutant and normal hemoglobins can detect the presence of a mutation site. The CE separation and mass analysis can be accomplished in typically 10-15 min. The unique capability of the CE/ESI-IT/reTOF system for detection of fast separations with narrow peaks that may be under 1 s fwhm is demonstrated. The speed of this system is essential for resolution of the large number of peaks that are separated in a short time duration using CE separations.

Adult↗

PubMed1997

Weight dissatisfaction and weight loss attempts among Canadian adults. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe the pattern of weight dissatisfaction and weight loss attempts among Canadian adults and the reasons for and methods of weight loss among those trying to lose weight. DESIGN: Population-based, cross-sectional surveys. SETTING: Ten Canadian provinces between 1986 and 1992. PARTICIPANTS: A probability sample of 29,855 men and women aged 18 to 74 years was selected using provincial health insurance registration files; this paper describes the subsample of 19,841 (66%) participants from whom anthropometric data were collected. OUTCOME MEASURES: Discrepancy between actual and desired body mass index (BMI); attempts to lose weight; reasons for losing weight; methods of weight loss used. RESULTS: Whether their weight was in the acceptable range (BMI 20-24 kg/m2) or at a level of increasing risk (BMI > or = 27 kg/m2), women were more likely than men to wish they weighed less and to be trying to lose weight; almost two-thirds of women but less than half the men with BMI > or = 27 kg/m2 were trying to lose weight. Even among those with BMI 20-24 kg/m2, 32% of women (v. 10% of men) were trying to reduce their weight. Weight dissatisfaction and current and past weight loss attempts were all negatively associated with age among women, but were unrelated to age among men. People with higher ratios of waist to hip circumference (WHR), controlling for BMI, were no more likely to be trying to lose weight than those with lower WHR; in fact, for women with BMI 27-29 kg/m2, WHR was negatively associated with prevalence of weight loss attempts. The presence of diabetes, hypertension and hypercholesterolemia was also unrelated to weight loss attempts; regular smokers and sedentary people were less likely to report trying to lose weight, controlling for BMI. Among those currently trying to lose weight, the most commonly mentioned reason was to improve general health, followed by increasing attractiveness. Overall, the most frequently mentioned method of weight loss was dieting, followed by exercise. CONCLUSIONS: Substantial numbers of men whose BMI places them at increased health risk appear to be content with their weight and are not attempting to reduce it. Conversely, women, especially the young and middle-aged, are likely to consider themselves above their desired weight and to be trying to lose weight, even when their weight is within acceptable limits. This reinforces the need to consider differences between men and women in efforts to promote and support healthy weights among Canadians.

Adult↗

PubMed1997

Risk factor correlates of body mass index. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To examine the association of obesity, as reflected by body mass index, with other cardiovascular risk factors specifically blood pressure, smoking, physical inactivity, plasma lipid levels and diabetes mellitus. DESIGN: Population-based, cross-sectional surveys. SETTING: Ten Canadian provinces between 1986 and 1992. PARTICIPANTS: A probability sample of 29,855 men and women aged 18 to 74 years was selected from the health insurance registration files of each province and invited to participate. Anthropometry was performed on 19,841 (66%) of these adults. OUTCOME MEASURES: Body mass index (BMI, kg/m2), systolic and diastolic blood pressure, smoking status, level of leisure-time physical activity, self-reported diabetes, levels of plasma total cholesterol, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL) and triglycerides (TRIG). RESULTS: The prevalence of high blood pressure increased with increasing BMI. The gradient of increase was steepest for younger (18-34 years) men and women compared with older (55-74 years) groups. The prevalence of physical inactivity in women tended to increase with increasing BMI except in the lowest BMI category. The J-shaped relationship, although weaker, was also seen in men. The prevalence of self-reported diabetes mellitus was greater with higher BMI categories at all ages and for both sexes except for the youngest group of men. The prevalence of dyslipidemia was related to BMI, as LDL and TRIG levels were higher and HDL levels lower in those with higher BMI. BMI was strongly related to blood pressure, diabetes mellitus and lipid abnormalities. CONCLUSION: These data suggest a central role for obesity in cardiovascular risk and the potential importance of intervention strategies aimed at reducing population obesity in the management of other cardiovascular risk factors.

Adult↗

PubMed1997

The association of cardiovascular disease risk factors with abdominal obesity in Canada. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To assess the degree of association of abdominal obesity with blood pressure and plasma lipid levels and to determine which anthropometric measures of obesity are most closely associated with these cardiovascular risk factors. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces (Alberta, Manitoba, Ontario, Quebec and Saskatchewan) between 1989 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 was selected using health insurance registration files in each province and invited to participate. A complete set of measurements was available for 8974 (56%) adults. OUTCOME MEASURES: Initially, simple correlation analyses by age and sex were performed between the anthropometric variables-body mass index, waist circumference (WC), hip circumference (HC), ratio of waist to hip circumference (WHR)- and cardiovascular disease risk variables-systolic blood pressure (SBP), diastolic blood pressure (DBP), levels of total cholesterol (TC), low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides (TRIG) and the TC/HDL ratio. Canonical correlation analyses were performed to determine the multivariate associations between the anthropometric and risk variables. RESULTS: The simple correlations between anthropometric variables and cardiovascular disease risk variables were highest for SBP; moderate for DBP, HDL, TRIG and TC/HDL; and lowest for LDL and TC. Of the anthropometric variables, WC demonstrated the greatest correlations with the risk variables. The first canonical correlations were significant (p < 0.0001) in men (0.58) and women (0.61) of all ages. Of the anthropometric variables, WC consistently demonstrated the highest loading values in the first canonical variable in men (0.56) and women (0.59). Of the risk variables in both sexes, the loadings of TRIG were generally the largest, those of HDL, SBP, DBP intermediate and those of LDL the smallest. In men, the strength of these associations generally decreased with age, whereas in women they peaked in the 35-54 year age group. CONCLUSION: Considerable association was seen between measures of abdominal obesity and blood pressure and plasma lipid levels. WC is the measure of abdominal obesity most highly correlated with these cardiovascular disease risk factors.

Abdomen↗

PubMed1997

Inhibition of lung surfactant secretion from alveolar type II cells and annexin II tetramer-mediated membrane fusion by phenothiazines.

We investigated the effects of phenothiazines on lung surfactant secretion from rat alveolar epithelial type II cells and on annexin II tetramer (Anx IIt)-mediated membrane fusion. Trifluoperazine and promethazine inhibited ATP-stimulated phosphatidylcholine (PC) secretion from type II cells in a dose-dependent manner. Concentrations that cause 50% inhibition (IC50) were approximately 3 and 25 microM for trifluoperazine and promethazine, respectively. Promethazine also inhibited PC secretion of type II cells stimulated by other secretagogues, including calcium ionophore A23187, phorbol 12-myristate 13-acetate, and terbutaline that are known to stimulate PC secretion via different signal transduction pathways. Since we have recently determined that Anx IIt is involved in PC secretion of type II cells, we examined whether phenothiazines influence Anx IIt's activity. Trifluoperazine and promethazine inhibited Anx IIt's ability to aggregate phosphatidylserine (PS) liposomes, to fuse PS/phosphatidylethanolamine (PE) liposomes, and to fuse PS/PE liposomes with lamellar bodies. These results suggest a relationship between lung surfactant secretion and Anx IIt-mediated membrane fusion.

Adenosine Triphosphate↗

PubMed1997

Overexpression of eukaryotic initiation factor 4E (eIF4E) in breast carcinoma.

BACKGROUND: Eukaryotic initiation factor 4E (eIF-4E) is a 25-kilodalton phosphoprotein that binds specifically to mRNA as the initial step for mRNA translation. An elevated level of eIF4E has been associated with the up-regulation of various protooncogene products. Transfection of cell lines by viral vectors with eIF4E overexpression has resulted in malignant transformation. The objective in this study was twofold: to examine benign and malignant breast specimens for eIF4E expression, and to determine whether eIF4E overexpression may have prognostic potential. METHODS: Western blot analysis was performed on benign and malignant breast specimens using anti-eIF4E rabbit antiserum. Quantification was accomplished by developing blots with nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate and densitometry. Confirmation of eIF4E overexpression at the cellular level was performed using immunohistologic staining in situ. RESULTS: The authors examined 112 breast specimens for eIF4E protein expression. Of the 52 benign breast specimens examined, none showed eIF4E overexpression. All 12 ductal carcinoma in situ specimens were found to overexpress eIF4E in the intermediate range (mean elevation: 2.5-fold). Of the 48 breast carcinoma specimens examined, all had eIF4E elevation at levels of 3-30-fold (mean: 10.5 +/- 0.9-fold). Charts from 39 patients with Stage I, II, and III breast carcinoma were reviewed. In ten patients with eIF4E overexpression of < sevenfold, there was no recurrence or death from breast carcinoma. In the 29 breast carcinoma patients with > or = 7-fold eIF4E overexpression, 9 patients had breast carcinoma recurrences and 5 had died from disease at last follow-up. The median follow-up in this study was 34.5 months. CONCLUSIONS: Overexpression of eIF4E was observed in malignant breast specimens but not in normal or benign breast tissues. In patients with breast carcinoma, the group with high eIF4E overexpression (> or = 7-fold) experienced a worse clinical outcome (higher recurrences and death) compared with the group with low eIF4E overexpression (< 7-fold).

Blotting, Western↗

PubMed1997

Mouse adhalin: primary structure and expression during late stages of muscle differentiation in vitro.

Adhalin, or alpha-sarcoglycan, is a 50-kDa glycoprotein that was originally characterized as a muscle membrane protein. The importance of adhalin is suggested by the diseases associated with its absence, notably the limb-girdle muscular dystrophies. However, the function of adhalin is unknown. To analyze the biological roles of adhalin, we cloned the mouse adhalin cDNA, raised peptide-specific antibodies to its cytoplasmic domain, and examined its expression and localization in vivo and in vitro. The mouse adhalin sequence was 80% identical to that of human, rabbit, and hamster. Adhalin was specifically expressed in striated muscle cells and their immediate precursors, and absent in many other cell types. Adhalin expression in embryonic mouse muscle was coincident with primary myogenesis. Its expression was found to be up-regulated at mRNA and protein levels during myogenic differentiation in vitro. The proper localization of adhalin to the muscle cell membrane was observed only in late stages of myotube maturation, coincident with the re-distribution of caveolin-3 and dystrophin. These data suggest that adhalin is highly specific for striated muscle and that it is linked with the formation of a fully functional muscle fiber.

Amino Acid Sequence↗