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PubMed1989

The reduced virulence of the thymotropic Moloney murine leukemia virus derivative MoMuLV-TB is mapped to 11 mutations within the U3 region of the long terminal repeat.

Chimeric constructs were generated by exchanging genomic fragments between the potent T-cell lymphoma inducer Moloney murine leukemia virus (MoMuLV) and its derivative MoMuLV-TB, which induces T-cell lymphoma after a relatively longer latent period. Analysis of the T-cell lymphoma-inducing potential of the hybrid viruses that were obtained localized the primary determinant critical to efficient T-cell lymphoma induction to the MoMuLV ClaI-XbaI fragment which comprises 48 nucleotides (nt) of p15E, p2E, the 3'-noncoding sequence, and 298 nt of U3. The 438-base-pair ClaI-XbaI fragments of MoMuLV and MoMuLV-TB differed in only 11 nt. Nine mutations were found within the enhancer. These mutations occurred within the two CORE, the two GRE-LVa, and two of the four NF1 nuclear factor-binding motifs. MoMuLV-TB replicated better than MoMuLV in thymus-bone marrow (TB) cells, a cultured cell line of lymphoid origin. In addition, MoMuLV-TB and NwtTB-2, a recombinant virus with the ClaI-SmaI fragment of MoMuLV-TB in a MoMuLV background, replicated in thymocytes as efficiently as did MoMuLV or TBNwt-2, the reciprocal recombinant virus, with the ClaI-SmaI fragment of MoMuLV in a MoMuLV-TB background. Like NwtTB-4, a recombinant virus with the ClaI-XbaI fragment of MoMuLV-TB in a MoMuLV background, NwtTB-2 induced lymphoma after a long latent period. The finding given above suggests that thymotropism is not the only factor that determines the T-cell lymphoma-inducing potential of MoMuLV. It appears likely that mutations in one or more of the MoMuLV-TB nuclear factor-binding motifs may have altered the interaction of the enhancer with specific nuclear factors; this, in turn, may affect the T-cell lymphoma-inducing potential of MoMuLV-TB.

Animals↗
PubMed1998

Curve walking in freely moving crayfish (Procambarus clarkii)

The curve walking of freely moving crayfish trained to walk along a curved path during homing behaviour was investigated using a video-analysis system. The leg kinematics and leg phase relationships, as well as the relationship between stepping patterns and body axis rotation measured relative to external references, were studied. The anterior and posterior extreme positions of the power stroke (AEP and PEP, respectively) and step amplitudes were analysed. As in a previous study on crayfish curve walking on a treadmill, PEPs were more posterior in outer legs (the legs on the outside of the turn) than in the inner legs. As a result, outer legs showed larger step amplitudes than inner legs. Leg kinematics varied within each walking sequence. AEP leg angles (the angles between the body and leg axes at the AEP) tended to decrease over time for inner legs and increase for outer legs. This leg angle drift was present mainly in the anterior legs and it suggests that these legs did not completely compensate for the body rotation after each step. In addition, leg angle asymmetries in a direction opposite to that of leg angle drift were observed at the start of each curve-walking sequence, suggesting that the extensive training (3 weeks) may have allowed crayfish to anticipate the leg angle drift. The rotational component of curve walking showed a discontinuous pattern, with the animal's body axis turning towards the inside of the curve only periodically. Analysis of cross-correlation functions showed that the angular acceleration of the body axis in the direction of the turn occurred during the power strokes of inner legs 2 and 5 and outer leg 4. While the tripod formed by these three legs showed in-phase relationships, the legs of the corresponding contralateral tripod (outer legs 2 and 5 and inner leg 4) were not in phase. We hypothesize that inner legs 2 and 5 and outer leg 4 act synergically causing the inward body rotation observed in curve-walking crayfish and that some of the asymmetries found in step geometry may be a passive phenomenon due to the body rotation.

Journal Article↗
PubMed1991

A sodium channel defect in hyperkalemic periodic paralysis: potassium-induced failure of inactivation.

Hyperkalemic periodic analysis (HPP) is an autosomal dominant disorder characterized by episodic weakness lasting minutes to days in association with a mild elevation in serum K+. In vitro measurements of whole-cell currents in HPP muscle have demonstrated a persistent, tetrodotoxin-sensitive Na+ current, and we have recently shown by linkage analysis that the Na+ channel alpha subunit gene may contain the HPP mutation. In this study, we have made patch-clamp recordings from cultured HPP myotubes and found a defect in the normal voltage-dependent inactivation of Na+ channels. Moderate elevation of extracellular K+ favors an aberrant gating mode in a small fraction of the channels that is characterized by persistent reopenings and prolonged dwell times in the open state. The Na+ current, through noninactivating channels, may cause the skeletal muscle weakness in HPP by depolarizing the cell, thereby inactivating normal Na+ channels, which are then unable to generate an action potential. Thus the dominant expression of HPP is manifest by inactivation of the wild-type Na+ channel through the influence of the mutant gene product on membrane voltage.

Electrophysiology↗
PubMed2006

New directions in biomedical text annotation: definitions, guidelines and corpus construction.

BACKGROUND: While biomedical text mining is emerging as an important research area, practical results have proven difficult to achieve. We believe that an important first step towards more accurate text-mining lies in the ability to identify and characterize text that satisfies various types of information needs. We report here the results of our inquiry into properties of scientific text that have sufficient generality to transcend the confines of a narrow subject area, while supporting practical mining of text for factual information. Our ultimate goal is to annotate a significant corpus of biomedical text and train machine learning methods to automatically categorize such text along certain dimensions that we have defined. RESULTS: We have identified five qualitative dimensions that we believe characterize a broad range of scientific sentences, and are therefore useful for supporting a general approach to text-mining: focus, polarity, certainty, evidence, and directionality. We define these dimensions and describe the guidelines we have developed for annotating text with regard to them. To examine the effectiveness of the guidelines, twelve annotators independently annotated the same set of 101 sentences that were randomly selected from current biomedical periodicals. Analysis of these annotations shows 70-80% inter-annotator agreement, suggesting that our guidelines indeed present a well-defined, executable and reproducible task. CONCLUSION: We present our guidelines defining a text annotation task, along with annotation results from multiple independently produced annotations, demonstrating the feasibility of the task. The annotation of a very large corpus of documents along these guidelines is currently ongoing. These annotations form the basis for the categorization of text along multiple dimensions, to support viable text mining for experimental results, methodology statements, and other forms of information. We are currently developing machine learning methods, to be trained and tested on the annotated corpus, that would allow for the automatic categorization of biomedical text along the general dimensions that we have presented. The guidelines in full detail, along with annotated examples, are publicly available.

Computational Biology↗
PubMed2001

Listing for lung transplantation: life expectancy and transplant effect, stratified by type of end-stage lung disease, the Eurotransplant experience.

BACKGROUND: Increased referral for lung transplantation, persistent shortage of donor lungs, and moderate transplant outcome call not only for adequate listing criteria, but also for an optimal allocation scheme. We used global cohort survival after listing and survival benefit from transplantation to study the effect of a lung allocation scheme, primarily driven by waiting time, on the different types of end-stage lung disease. METHODS: We followed all adult patients consecutively listed for first, lung-only transplantation between 1990 and 1996 (n = 1,208) for at least 2 years, with an additional 2-year follow-up after transplantation (n = 744). We used the competing risk method, the Kaplan-Meier method, and a time-dependent non-proportional hazards model to analyze waiting-list outcome and global mortality after listing, post-transplant survival, and transplant effect, respectively. Each analysis was stratified for type of end-stage lung disease. RESULTS: At 2 years, 57% of the total cohort had received lung transplants, whereas 25% had died on the waiting list. The 2-year survival post-transplant was 55%. The global mortality of the cohort, since listing, amounted to 46% at 2 years. Compared with continued waiting, patients experienced benefit from transplantation by Day 100, which lasted until the end of the 2-year analysis period. We noticed the highest global mortality rates for patients with pulmonary fibrosis and pulmonary hypertension (54% and 52%); emphysema patients had the lowest (38%). Patients with pulmonary fibrosis and cystic fibrosis had much earlier benefit from transplantation, 55 and 90 days, respectively. Transplantation also benefited emphysema patients by Day 260. CONCLUSIONS: Lung transplantation conferred transplant benefit in a Western European cohort of adults, in particular for patients with pulmonary fibrosis and cystic fibrosis, but also for patients with emphysema. The global survival rate, reflecting the real life expectancy for a newly listed transplant candidate, is poor for patients with pulmonary fibrosis and pulmonary hypertension. Allocation algorithms that lessen the impact of waiting time and take into account the type of end-stage lung disease should be developed.

Adolescent↗
PubMed1991

Heptad motifs within the distal subdomain of the coiled-coil rod region of M protein from rheumatic fever and nephritis associated serotypes of group A streptococci are distinct from each other: nucleotide sequence of the M57 gene and relation of the deduced amino acid sequence to other M proteins.

Streptococcal M protein, a dimeric alpha helical coiled-coil molecule, is an antigenically variable virulence factor on the surface of the bacteria. Our recent conformational analysis of the complete sequence of the M6 protein led us to propose a basic model for the M protein consisting of an extended central coiled-coil rod domain flanked by a variable N-terminal and a conserved C-terminal end domains. The central coiled-coil rod domain of M protein, which constitutes the major part of the M molecule, is made up of repeating heptads of the generalized sequence a-b-c-d-e-f-g, wherein "a" and "d" are predominantly apolar residues. Based on the differences in the heptad pattern of apolar residues and internal sequence homology, the central coiled-coil rod domain of M protein could be further divided into three subdomains I, II, and III. The streptococcal sequelae rheumatic fever (RF) and acute glomerulonephritis (AGN) have been known to be associated with distinct serotypes. Consistent with this, we observed that the AGN associated M49 protein exhibits a heptad motif that is distinct from the RF associated M5 and M6 proteins. Asn and Leu predominated in the "a" and "d" positions, respectively, in subdomain I of the M5 and M6 proteins, whereas apolar residues predominated in both these positions in the M49 protein. To establish whether the heptad motif of M49 is unique to this protein, or is a general characteristic of nephritis-associated serotypes, the amino acid sequence of M57, another nephritis-associated serotype, has now been examined. The gene encoding M57 was amplified by PCR, cloned into pUC19 vector, and sequenced. The C-terminal half of M57 is highly homologous to other M proteins (conserved region). In contrast, its N-terminal half (variable region) revealed no significant homology with any of the M proteins. Heptad periodicity analysis of the M57 sequence revealed that the basic design principles, consisting of distinct domains observed in the M6 protein, are also conserved in the M57 molecule. However, the heptad motif within the coiled-coil subdomain I of M57 was distinct from M5 and M6 but similar to M49. Similar analyses of the heptad characteristics within the reported sequences of M1, M12, and M24 proteins further confirmed the conservation of the overall architectural design of sequentially distinct M proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed2000

Service use and cost by mentally ill chemical abusers: differences by retention in a therapeutic community.

PURPOSE: Earlier research estimated the incremental costs and outcomes of a modified therapeutic community (modified TC) for mentally ill chemical abusers (MICAs) relative to a treatment-as-usual (TAU) control group. The present study extended the cost analysis by disaggregating the modified TC group into clients who completed the program (completers) and clients who dropped out (separaters). METHODS: Bivariate and multivariate analyses were conducted to estimate differences in treatment and other service costs among completers, separaters, and TAU. Subjects were sequentially assigned to the modified TC (n = 171) or TAU (n = 47), and the analysis period covered 12 months post-baseline. Using a standardized instrument to collect resource use and cost data, the estimated weekly cost per client in the modified TC was $554, with completers showing a larger average cost of treatment ($27,595) than separaters ($9,986). RESULTS: The average TAU subject had a much higher cost for other (non-modified TC) services ($29,795) relative to separaters ($22,048) or completers ($1,986). These findings suggest that, from baseline to the 12-month follow-up, the total cost of modified TC treatment and other services for completers may be slightly lower than the total cost for separaters or TAU subjects. Since the modified TC group had better outcomes than the TAU group, and the completers had better outcomes than the separaters, the modified TC program could be an effective mechanism to reduce the costs of service utilization as well as improve clinical outcomes. IMPLICATIONS: This detailed investigation into service utilization and cost provides policy-makers and program directors with valuable information regarding potentially cost-effective interventions and further underscores the importance of retention in treatment for this vulnerable population.

Adult↗
PubMed1999

Prevalence of upper gastrointestinal symptoms in the general population: a systematic review.

BACKGROUND: A systematic review was undertaken of all studies published as of December 1997, on the population prevalence of upper gastrointestinal (GI) symptoms. METHODS: Studies excluded from consideration were those conducted on subjects attending hospital or primary care clinics, or who were hospitalized or institutionalized; or where studies were conducted in the workplace or on occupational groups. Studies meeting the following criteria were included in the comparative analysis: period studied, sample size and response rate all reported; vague terms such as 'dyspepsia' or 'indigestion' defined if enquired about; abdominal pain or discomfort enquired about; patients with a history, or evidence, of organic disease not excluded from the results. Follow-up studies on groups of patients previously studied were also not included. RESULTS: In the 10 selected studies, the reported prevalence of upper abdominal symptoms (mostly upper abdominal pain or discomfort) ranged from approximately 8% to 54%, while the prevalence of heartburn and/or regurgitation ranged from 10% to 48% for heartburn, from 9% to 45% for regurgitation and 21% to 59% for both/either. CONCLUSIONS: In the case of upper abdominal symptoms, the most likely explanation for the broad range of prevalence reported is variation in the definition of symptoms. In the case of heartburn and regurgitation, different understandings of these terms by different investigators and subjects may have contributed to the range of results. Symptom definitions and what is understood by them should be among the most important considerations when undertaking population prevalence studies on upper GI symptoms, to allow comparisons to be made between studies.

Abdominal Pain↗
PubMed1998

The National Cancer Data Base report on patterns of care for adenocarcinoma of the rectum, 1985-95.

BACKGROUND: The Commission on Cancer data from the National Cancer Data Base (NCDB) examining current time trends (1985-1995) in stage of disease, treatment patterns, and survival relating to patients with rectal adenocarcinoma are described in this report. METHODS: Seven calls for data to hospital cancer registries across the U.S. have yielded a total of 5,850,000 cancer cases for the years 1985-1995 and include 20,461 rectal and rectosigmoid junction adenocarcinoma cases in 1985-1986, 36,007 cases in 1989-1990, and 42,069 cases in 1994-1995. These data represent 24.4%, 44.5%, and 52.5%, respectively, of the estimated cases of rectal and rectosigmoid adenocarcinoma cases diagnosed in the U.S. in each of the 3 respective time periods. Analysis of the data is limited to cases with American Joint Committee on Cancer (AJCC) Stage I-IV disease. RESULTS: Four trends were observed. 1) Stage I disease was diagnosed with decreasing frequency, decreasing from 37.1% of cases with known AJCC stage of disease in 1985-1986 to 33.8% in 1994-1995. 2) There was an increase in the frequency with which local excision was utilized as all or part of the primary treatment for Stage I disease. 3) Stage for stage, there was an increase in the frequency with which anterior/posterior resections were utilized and a corresponding decline in the use of abdominoperineal resections. 4) Multimodal treatment regimens are being used with greater frequency, particularly in patients with Stage II and III disease. CONCLUSIONS: The NCDB data have important implications for analyzing cancer treatment and outcome in the U.S. These data suggest that rectal adenocarcinoma is being diagnosed at a later stage, especially among the young and African Americans. The guidelines for colorectal carcinoma screening issued by the American Cancer Society and the American Gastroenterological Association should be promoted more vigorously to increase the proportion of patients presenting with early stage disease and improve overall survival. The increased use of multimodal therapy for the treatment of Stage II and III disease continues.

Adenocarcinoma↗
PubMed1993

A new tumor-associated antigen defined by a monoclonal antibody directed to gastric adenocarcinoma.

BACKGROUND: To develop useful markers for the gastrointestinal neoplasms, the authors have established a new monoclonal antibody (MoAb), FU-MK-1, directed to gastric adenocarcinoma. METHODS: The MoAb was produced by a mouse hybridoma technique by immunizing a BALB/c mouse with cancerous ascites derived from a poorly differentiated adenocarcinoma of the stomach. RESULTS: FU-MK-1 did not react with the normal adult gastric mucosa, but did react with most carcinomas of the gastrointestinal tract. In addition, the MoAb recognized cholangiocarcinomas (CC), but it did not react with hepatocellular carcinomas (HCC). Furthermore, in the combined type tumor consisting of a mixture of HCC and CC, the MoAb react only with CC element, but not with pseudoglandular structures in the HCC areas. These results indicate that FU-MK-1 is a useful antigenic marker for distinguishing HCC from CC in the liver. Furthermore, because this MoAb retains its reactivity with formalin-fixed paraffin-embedded material, it may become a useful reagent for routine or retrospective immunohistologic studies. The molecular weight of the FU-MK-1 antigen was estimated to be ca. 41,000 dalton by the Western blot analysis. Periodic acid and trypsin treatment on the antigen suggested that the antigenic determinant is a glycoprotein. CONCLUSIONS: This MoAb may contribute to the histopathologic and immunologic studies of the digestive system.

Adenocarcinoma↗
PubMed1994

Trial of immunosuppression in amyotrophic lateral sclerosis using total lymphoid irradiation.

Although the cause of amyotrophic lateral sclerosis (ALS) remains unknown, recent studies have suggested an autoimmune mechanism of pathogenesis. Previous trials of immunosuppressive treatment have yielded inconclusive results. Our study was designed to determine whether more powerful and prolonged immunosuppression, produced by total lymphoid irradiation (TLI), would alter the course of ALS. In a double-blind, randomized, placebo-controlled study, 30 patients with classic ALS were treated with TLI, and 31 were given sham radiation. Quantitative measurements of muscle strength, functional motor activity, and humoral and cellular immune status were followed for 2 years, or until death or respirator dependence. Motor function in the TLI-treated and control groups showed no significant differences throughout the study. Overall survival was not significantly different in the TLI-treated and control groups. TLI effectively suppressed cellular and humoral immune function throughout the 2-year study period. Analysis of the relationship between immunosuppression and motor functions showed no consistent effect of treatment. We conclude that powerful and prolonged immunosuppression produced by TLI did not benefit patients with ALS. This fails to support the concept of an autoimmune mechanism of pathogenesis of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed2006

Development and validation of a sensitive quantification method for hematoporphyrin monomethyl ether in plasma using high-performance liquid chromatography with fluorescence detection.

A rapid, sensitive, precise and specific method for determination of hematoporphyrin monomethyl ether (HMME), a novel photodynamic therapy (PDT) drug, was developed and validated using high-performance liquid chromatography (HPLC) with fluorescence detection. HMME was isolated from the plasma by a single-step liquid-liquid extraction with ethyl acetate. The analyte and internal standard fluorescein were baseline separated on a Diamonsil C(18) analytical column (4.6 x 150 mm, 5 microm) and analyzed using a fluorescence detector with the excitation and emission wavelengths set at 395 and 613 nm, respectively. The method was linear in the concentration range 0.025-5 microg/mL with a lower limit of quantitation (LLOQ) of 10 ng/mL. The inter- and intra-day accuracies and precisions were all within 10% and the mean recoveries of HMME and fluorescein were 95 +/- 3.7 and 90 +/- 2.3%, respectively. The analyte was stable during all sample storage, preparation and analysis periods. This method was successfully applied to a pharmacokinetic study after a single-dose intravenous administration of HMME (5 mg/kg) to beagle dogs. This method was reproducible and sensitive enough for the pharmacokinetic study of HMME. Based on the results of the pharmacokinetic study, we suggest that a rather long light-avoiding time is essential for patients under HMME therapy.

Animals↗
PubMed2002

Trends in cancer patient survival in Estonia before and after the transition from a Soviet republic to an open-market economy.

Cancer patients' survival is strongly dependent on socioeconomic factors, including access to and quality of medical care. During the past decade, Estonia has undergone a major political and economic change from a Soviet republic to an open-market economy country, and the health care system was transformed from a centralised state-controlled system into a decentralised health insurance-based one. Using data from the population-based Estonian Cancer Registry, we assessed trends in cancer patient survival before and after this transition by application of period analysis, a new method of survival analysis, which allows more timely disclosure of time trends than traditional survival analysis. Our study included 83,138 patients diagnosed with 1 of the 11 most frequent malignancies in Estonia from 1969-1998. Patients were followed up to the end of 1998. Despite a moderate increase in 5- and 10-year relative survival over time, prognosis for many common forms of cancer, such as stomach, colorectal, breast and ovarian cancer, remained considerably worse than the survival rates achieved in more affluent European countries many years ago. By contrast, a very steep increase in survival rates was observed for common urologic cancers, including prostate, kidney and bladder cancer, which went along with a rise in incidence rates of these cancers over time. For prostate cancer, similar survival rates as in other European countries have now been achieved. The most likely explanation for these trends is enhanced availability and utilization of laboratory and technical diagnostic equipment. Despite recent improvement, major efforts in delivering modern cancer care to the population of Estonia will be required to close the gap that continues to exist between prognosis of cancer patients in this country and other European countries.

Age Distribution↗
PubMed1996

Pharmacokinetics of cyclosporine after renal transplant in children.

The pharmacokinetics of cyclosporine and the relationship between blood levels and average drug concentration were prospectively evaluated in 18 children 1 month after renal transplantation. All children had normal renal function and no hepatic or gastrointestinal dysfunction. Cyclosporine was administered after an overnight fast, and serial blood samples were drawn over a 24-hour period. Analysis of cyclosporine levels was performed by means of monoclonal radio immunoassay on whole blood. Children were divided into three age groups for comparison: 2-5 years, 5-10 years, and > 10 years. There were no differences between age groups in serum protein, serum lipids, or hemoglobin levels, or in the pharmacokinetic parameters of cyclosporine except as follows: significant differences were noted in cyclosporine dose based on body weight, apparent steady-state volume of distribution, and apparent blood clearance, with the youngest children (2-5) requiring higher doses, a relative greater distribution, and exhibiting more rapid drug clearance than those > 10 years of age. In addition, we observed diurnal variation in trough levels, with morning levels (0 hr) significantly higher than those obtained in the evening (12 hours after administration of cyclosporine). Trough levels demonstrated a fair correlation with area under the concentration-time curve (AUC) and average concentration (Cav), but an abbreviated kinetic profile using cyclosporine levels 1 and 3.5 hours after administration accurately predicted AUC.

Adolescent↗
PubMed1993

Sequestration and secretion of insulin-like growth factor-I by bovine aortic endothelial cells.

Endothelial cells elaborate growth promoting activities in culture medium that support limited smooth muscle cell and fibroblast growth in vitro in the absence of serum. We investigated whether insulin-like growth factor-I (IGF-I) was synthesized and secreted by bovine aortic endothelial cells in vitro. Subconfluent endothelial cell cultures in serum-free medium secreted severalfold higher IGF-I levels than confluent cultures by acid-sizing chromatography and IGF-I radioimmunoassay. The IGF-I secretory level was not sustained during a second serum-free incubation. In contrast, secretion of IGF binding proteins persisted and was maintained at constant levels throughout the same observation periods. Analysis of poly(A+)RNA by northern blots revealed hybridization of an IGF-I cDNA to a 7.5- to 7.0-kb transcript and superinduction of the 7.5-7.0-kb mRNA by the translational inhibitor, cyclohexamide. However, no endogenously labeled IGF-I was detected in conditioned media after incubation of cultures with [35S]cysteine or [3H]leucine. When cultures were incubated in the presence of serum supplemented with IGF-I, subconfluent cultures sequestered and released more IGF-I than confluent cultures. We concluded that the majority of IGF-I secreted in vitro was sequestered from serum.

Animals↗
PubMed2004

Stable carbon and oxygen isotopic determination of sub-microgram quantities of CaCO3 to analyze individual foraminiferal shells.

We have developed an analytical system to determine stable isotopic compositions (delta13C and delta18O) of sub-microgram quantities of CaCO3 for the purpose of analyzing individual foraminiferal shells, using continuous-flow isotope ratio mass spectrometry (CF-IRMS). The system consists of a micro-volume CaCO3 decomposition tube, stainless steel CO2 purification vacuum line with a quantity-regulating unit, helium-purged CO2 purification line, gas chromatograph, and a CF-IRMS system. By using this system, we can determine stable carbon and oxygen isotopic compositions as low as 0.2 microg of CaCO3, with standard deviations of +/-0.10 per thousand for delta13C and +/-0.18 per thousand for delta18O within a 4-h reaction time and 30-min analysis period.

Animals↗
PubMed1997

Analysis of O-linked oligosaccharide alditols by high-pH anion-exchange chromatography with pulsed amperometric detection.

To apply high-pH anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) to the accurate and sensitive analysis of O-linked oligosaccharide alditol, removal of glycopeptides and peptides from oligosaccharide samples obtained by beta-elimination was first investigated. The results obtained by using fetuin as a model glycoprotein indicated that (glyco)peptides derivatized by fluorescamine are easily removed from the beta-eliminated oligosaccharide sample by means of a Sep-Pak C18 cartridge due to their increased hydrophobicity. This clean-up procedure was also effectively applied to the beta-eliminated oligosaccharide sample obtained from delipidated sheep erythrocyte ghosts. Furthermore, structural analysis of the oligosaccharide alditols by HPAEC-PAD was successfully performed in combination with partial and complete desialylation, composition analysis, periodate oxidation, and glycosidase digestion and revealed that sheep erythrocyte membrane glycoproteins contain Gal beta 1-->3Gal-NAc and Gal beta 1-->4GlcNAc beta 1-->3Gal beta 1-->3GalNac, to which one or two residues of Neu5Ac and Neu5Gc are attached in different combinations.

Animals↗
PubMed1998

G2 restriction point within populations of hepatocytes and tongue keratinocytes in young, growing mice.

The authors studied the effect of either extracts from liver (LE) or the malignant tumour ES2 (TE) or plasma from intact mice (PI) or tumour-bearing animals (PT) on the mitotic activity of the hepatocytes and tongue keratinocytes in young, growing C3H/s male mice (28+/-1 days old). Animals standardized for periodicity analysis were injected intraperitoneally with either TE, LE, PI, PT, or saline (S) at 16:00 h with 0.01 ml of sample/g of body weight and were then killed at (time of day/h post-injection) 20:00/04, 00:00/08, and 04:00/12. Colchicine (2 microg/g) was injected 4 h before death. Samples of the liver and tongue from each animal were processed for histology and assessment of mitotic index. The results were expressed as colchicine-arrested metaphases/1000 nuclei. The TE and LE stimulated the mitotic activity of hepatocytes and tongue keratinocytes. Taking into account the time elapsed between the injections and the measurements made in these light-dark synchronized animals, we conclude that the increase in mitotic index observed in those tissues stemmed from a reinitiation of cell-cycle traverse in a subpopulation of G2-arrested, noncycling cells.

Aging↗