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PubMed1997

Interactive effects of dietary chromium tripicolinate and crude protein level in growing-finishing pigs provided inadequate and adequate pen space.

An experiment was conduct to determine the interactive effects of dietary chromium tripicolinate (CrPic), CP, and pen space (PS) as a stress on growth performance, carcass traits, and plasma hormones and metabolites of crossbred growing-finishing pigs (128 pigs; initial BW 27.2 kg). A factorial arrangement of treatments included two levels of Cr (0 and 400 ppb as CrPic), two levels of CP (80 [80P] and 120% [120P] of the lysine requirement; NRC, 1988), and two levels of PS (adequate [APS] or inadequate [IPS]). In the grower phase, ADG was decreased more by IPS when pigs were fed 80P (CP x PS, P < .08). Gain/feed (G/F) was decreased by IPS in pigs fed 80P; however, in pigs fed 120P, IPS increased G/F (CP x PS, P < .01). Supplemental Cr did not affect (P > .10) ADG, ADFI, or G/F in the grower phase. In the finisher phase, pigs, fed 120P had less (P < .10) ADFI but similar (P > .10) ADG compared with pigs fed 80P. Gain/feed was higher (P < .10) in pigs fed 120P than in pigs fed 80P. Daily gain ADFI were lower (P < .03) in pigs provided IPS than in pigs provided APS. In pigs fed 80P, CrPic tended to result in higher ADG and G/F; however, in pigs fed 120P, Cr tended to result in lower ADG and G/F (CP x Cr, P < .09). Pigs fed 120P had greater (P < .03) longissimus muscle area (LMA) and percentage of muscling (PM) and less (P < .03) 10th rib fat thickness (TRF) than pigs fed 80P. Pigs provided IPS had greater LMA and PM and less TRF than pigs provided APS (P < .03). Pigs fed CrPic had higher TRF when provided IPS but lower TRF when provided APS (Cr x PS, P < .07). Feeding CrPic had minimal effect on plasma urea N, cholesterol, glucose, NEFA, insulin, or growth hormone.

Analysis of Variance↗
PubMed2001

Telomere erosion is independent of microsatellite instability but related to loss of heterozygosity in gastric cancer.

AIM: To correlate the length of the telomere to microsatellite instability (MSI) and loss of heterozygosity (LOH) of APC, MCC and DCC genes in gastric carcinomas. METHODS: Telomeric restriction fragment (TRF) length of gastric cancer was measured with Southern blot. LOH of APC, MCC and DCC genes, microsatellite instability (MSI) and frameshift mutation of hMSH6, TGF-betaRII and BAX genes were analyzed by PCR-based methods. RESULTS: Sixty-eight cases of sporadic gastric carcinoma were studied for MSI using five microsatellite markers. MSI in at least one locus was detected in 17 (25%) of 68 tumors analyzed. Frameshift mutations of hMSH6, TGF-betaRII and BAX were detected in 2,6 and 3 of gastric carcinomas respectively showing high MSI (> or = 2 loci, n = 8), but none was found in those showing low MSI (only one locus, n = 9) or MSS (tumor lacking MSI or stable, n = 51). Thirty-five cases, including all high MSI and low MSI, were studied for TRF. The mean TRF length was not correlated with clinicopathological parameters. No association was observed between TRF length and MSI or frameshift mutation. On the contrary, LOH at the DCC locus was related to telomere shortening (P<0.01). This tendency was also observed in APC and MCC genes, although there was no statistical significance. CONCLUSION: The development of gastric cancer can arise through two different genetic pathways. In high MSI gastric cancers, defective mismatch repair allows mutations to accumulate and generate the high MSI phenotype. In gastric cancers showing either low MSI or MSS, multiple deletions may represent the LOH pathway. Telomere erosion is independent of high MSI phenotype but related to the LOH pathway in gastric cancer.

Adult↗
PubMed1999

Telomere stability is frequently impaired in high-risk groups of patients with myelodysplastic syndromes.

Genomic instability induces an accumulation of genetic changes and may play a role in the pathogenesis of myelodysplastic syndromes (MDS). To clarify the possible association between genomic instability and clinical outcome in MDS patients, we compared telomere dynamics to the recently established International Prognostic Scoring System (IPSS) risk groups for MDS. We measured the terminal restriction fragments (TRFs) of 93 patients with MDS at the time of diagnosis, and telomerase activity was analyzed in 62 patients with MDS using the PCR-based telomeric repeat amplification protocol (TRAP) assay. A total of 53 of 93 MDS patients had TRFs within the age-matched normal range, and the remaining patients showed shortened TRFs (35 patients) or elongated TRFs (5 patients). MDS patients with shortened TRFs had a significantly low hemoglobin concentration (P = 0.04), a high percentage of marrow blasts (P = 0.02), and a high incidence of cytogenetic abnormalities (P < 0.05). The incidence of leukemic transformation was significantly high in patients with shortened TRF length (P < 0.05). In addition, patients with shortened TRF length were frequently seen in the IPSS high-risk group (P < 0.01). Most of the MDS patients had normal-to-low levels of telomerase activity, suggesting that changes in TRF length rather than telomerase activity may more accurately reflect the pathophysiology of MDS. MDS patients with shortened TRF length had a very poor prognosis (P < 0.01), suggesting that telomere dynamics may be linked to clinical outcome in MDS patients. Thus, an abnormal mechanism of telomere maintenance in subgroups of MDS patients may be an early indication of genomic instability. This study demonstrates that telomere stability is frequently impaired in a high-risk group of MDS patients and suggests that, in combination with the IPSS classification system, measurement of TRFs may be useful in the future to stratify MDS patients according to risk and manage the care of MDS patients.

Acute Disease↗
PubMed1979

Characterization of "thyroliberin-deamidating enzyme" as a post-proline-cleaving enzyme. Partial purification and enzyme-chemical analysis of the enzyme from anterior pituitary tissue.

An enzyme which catalyzes the deamidation of thyroliberin (TRF; less than Glu-His-Pro-NH2) has been purified 110-fold from extracts of bovine anterior pituitary by ammonium sulfate fractionation, ion exchange chromatography on DEAE-cellulose, and gel filtration. This enzyme of 76,000 molecular weight (as estimated by gel filtration) exhibits maximal activity at neutral pH (optimum pH 7.4 to 7.6) in buffers of high ionic strength supplemented with thiol-protecting agents. As indicated by the strong inhibition of the enzymatic activity by N-ethylmaleimide and Hg2+, as well as by the extreme sensitivity toward diisopropyl fluorophosphate, -SH, and -OH residues apparently represent essential functional groups of the enzyme. The stereospecific deamidation of TRF (Km = 4.1 . 10(-4) M) is inhibited competitively by TRF analogues which contain proline or by the proline containing biologically active peptides luliberin (LH-RF), oxytocin, vasopressin, angiotensin II, and Substance P. TRF analogues without proline or peptide amides without proline are ineffective. This enzyme cleaves the appropriate Pro-X bonds in luliberin, angiotensin II, pyroGlu-His-Pro-Gly-NH2, and the collagenase substrate Z-Gly-Pro-Leu-Gly-Pro. Thus, it may be characterized as a post-proline-cleaving enzyme.

Amidohydrolases↗
PubMed2003

Telomere dynamics in myelodysplastic syndrome determined by telomere measurement of marrow metaphases.

Myelodysplastic syndrome (MDS), which is known to be a preleukemic state, is a heterogeneous entity characterized by ineffective hematopoiesis and dysplastic morphological features. Most MDS patients show erosive telomeric repeats (TTAGGG)(n), without up-regulation of telomerase activity, suggesting that telomere shortening may be linked to cellular senescence in MDS. We measured telomere length in samples from 13 MDS patients and 8 healthy volunteers, based on telomere signals of individual chromosomes, using digital images of metaphases after quantitative fluorescence in situ hybridization (Q-FISH) with peptide nucleic acid probes and compared the results with results obtained with the standard method of determining terminal restriction fragment (TRF) length. In healthy volunteers, we found a significant correlation between TRF length and telomere fluorescence signals detected by Q-FISH, and a relatively wide distribution of fluorescence telomere signals was demonstrated in every sample. In contrast, we found no linear correlation between TRF length and telomere fluorescence signals in MDS, and most MDS patients showed weak telomere fluorescence signals, corresponding to short telomeres, with a narrow range compared with normal subjects. TRF length represented telomere DNA in whole marrow cells, whereas telomere fluorescence signals by Q-FISH represented only marrow metaphases corresponding to MDS-derived cells. Metaphases from most MDS patients showed homogeneous telomere shortening, irrespective of the presence of cytogenetic abnormality. In contrast, marrow metaphases from normal individuals showed a relatively wide range of telomere signals in each metaphase, indicating that in MDS cells, telomere shortening mechanisms that normally exist might be dysregulated. Therefore, analysis of telomere distribution as well as average telomere length detected by Q-FISH might be useful to clarify the telomere dynamics of MDS cells.

Adult↗
PubMedDate not supplied

Iron metabolism, inflammation and anemia in critically ill patients. A cross-sectional study.

INTRODUCTION: For critically patients, enteral immunonutrition results in notable reductions in infections and in length of stay in hospital, but not on mortality, raising the question as to whether this relate to the heterogeneous nature of critically ill patients or to the absence of the altered absorption of specific nutrients within the immunonutrient mix (e.g. iron). Immune-associated functional iron deficiency (FID) is not only one of the many causes or anaemia in the critically ill, but also a cause of inappropriate immune response, leading to a longer duration of episodes of systemic inflammatory response syndrome and poor outcome. OBJECTIVE: This prospective cross-sectional study was undertaken to assess the prevalence of FID in critically ill patients during their stay in intensive care (ICU) in order to find the more appropriate population of patients that can benefit from iron therapy. METHOD: Full blood cell counts, including reticulocytes (RETIC), serum iron (SI), transferring levels (TRF) and saturation (satTRF), serum TFR receptor (sTfR), ferritin (FRT) and C-reactive protein (CRP) were measured in venous blood samples from 131 random patients admitted to the ICU for at least 24 h (Length of ICU stay, LIS; min: 1 day; max: 38 days). RESULTS: Anaemia (Hb < 12 g/dL) was present in 76% of the patients (Hb < 10 g/dL in 33%), hypoferremia (SI < 45 microg/dl) in 69%; satTRF < 20% in 53%; FRT < 100 ng/mL in 23%; sTfR > 2.3 mg/dL in 13%; and CRP > 0.5 mg/dL in 88%. Statistically significant correlations (r of Pearson; *p < 0.05, **p < 0.01) were obtained for serum CRP levels and WBC**, Hb*, TRF**, satTRF*, and FRT**. There was also a strong correlation between TRF and FRT (-0.650**), but not between FRT and satTRF or SI. LIS correlated with Hb*, CRP**, TRF*, satTRF* and FRT**. CONCLUSIONS: A large proportion of critically ill patients admitted to the ICU presented the typical functional iron deficiency (FID) of acute inflammation-related anaemia (AIRA). This FID correlates with the inflammatory status and the length of stay at the ICU. However, 21% of the ICU patients with AIRA had an associated real iron deficiency (satTRF < 20; FRT < 100 and sTfR > 2.3). Since oral supplementation of iron seems to be ineffective, all these patients might benefit of iv iron therapy for correction of real or functional iron deficiency, which in turn might help to ameliorate their inflammatory status.

Anemia↗
PubMed2005

[Correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cells].

BACKGROUND & OBJECTIVE: Many studies showed that telomere length and telomerase activity closely correlate with proliferation and malignant degree of tumor cells, and both of them might be involved in the repair of radiation-induced DNA damage. So it was speculated that telomere length and telomerase activity maybe correlate to radiosensitivity of carcinoma cells. This study was designed to investigate the correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cell line Hep-2. METHODS: Hep-2 cells were irradiated with 0, 2, 4, 8, or 12 Gy of gamma-ray for 3 times. Survival cells were subcultured for 20 generations. Radiosensitivity index, survival fraction at 2 Gy (SF(2)), was measured by clone formation assay. Telomere length (mean length of telomere restriction fragments, TRF) was examined by Southern blotû telomerase activity (TA) was detected by polymerase chain reaction-based telomeric repeat amplification protocol (PCR-TRAP) coupled with ELISA. RESULTS: After different doses of irradiation, SF(2) of Hep-2 cells was 0.47-0.64; TRF was 3.76-9.43 kb; TA was 1.761-2.606. Each parameter had significant differences among the survival progenies (P<0.05). SF(2) was positively correlated with TRF (r=0.921, P<0.01), and negatively correlated with TA (r=-0.929, P<0.01); TRF was negatively correlated with TA (r=-0.944, P<0.01). CONCLUSION: Radiosensitivity of Hep-2 cells negatively correlates with telomere length, and positively correlates with telomerase activity, which suggest that both telomere length and telomerase activity may be used to predict cellular radiosensitivity.

Carcinoma, Squamous Cell↗
PubMed2006

Time-resolved fluorescence detection of mosaic DNA chip.

We demonstrated a time-resolved fluorescence (TRF) label and detection of mosaic DNA chip in this paper. We synthesized oligonucleotide sequences in situ on glass slides directly, and then sliced them up into small pieces and patched up the pieces bearing different sequences to generate a mosaic DNA chip. With multiple 4, 7-bis(chlorosulfophenyl)-1, 10-phenanthroline-2, 9-dicarboxylic acid (BCPDA, abbreviated as BCPDA) labeling method based on avidin-biotin amplification, we established a TRF detection format on the mosaic DNA chip. The detection method allows discriminatory signals for perfect match, one-base mismatch, two-base mismatch, and three-base mismatch by TRF labeled DNA hybridization, whereby Europium (III, Eu3+) was captured and released on the principle of complexation and dissociation interaction between BCPDA and Eu3+ solution when the BCPDA-tagged avidin and biotin-capped oligonucleotide sequence linked. The fluorescence spectra and related lifetimes were determined. We also compared the TRF detection mode with the conventional fluorescence one. These results showed the former is a potential alternative replacement of the latter, especially for labeling the mosaic DNA chip. The discovery is of fundamental interest and has significant implications to biochips and biosensors based on time-resolved-fluorescence detection.

Avidin↗
PubMed1991

[The mechanisms of the disorder of calcium homeostasis in terminal kidney failure and the allotransplantation of a cadaver kidney].

Overall 34 patients with terminal renal failure (TRF) and 81 recipients of the allotransplanted cadaveric kidney (ACK) were examined. It has been established in in-vitro experiments with modulated by additions of EDTA to the plasma and CaCl2 hypo- and hypercalcemia that the magnitude of bound calcium (standardized at the concentration of ionized calcium-Ca++1 mmol/l) decreased in the blood plasma in 65 and 61% of cases. Besides protein-bound calcium dropped in 94 and 91% of cases; the total buffer capacity of the plasma and buffer capacity of proteins fell in 59 and 87% of cases in TRF and ACK, respectively. The rise of the Ca++ content on an empty stomach seen in 21 out of 99 patients with TRF and in 42 out of 98 recipients of the ACK was caused by a decrease of calcium binding in the blood plasma, not made for by the fall of calcium supply to the blood because of "tertiary" hyperparathyroidism. Hypocalcemia detected in 38% of TRF patients was consequence to the rise of calcium binding not made for by the increased calcium supply to the blood provoked by bone resistance to parathyroid hormone.

Buffers↗
PubMed1990

[Disordered lipid metabolism and the morphofunctional instability of the erythrocyte membranes in patients with terminal kidney failure].

Fifty-two patients with terminal renal failure (TRF) placed on elective hemodialysis were examined for serum lipids and red blood cell membranes with the aid of chromatographic separation of lipids in thin-layer silica gel on Silufol plates followed by densitometry. Spectrocytophotometry was employed to study red blood cell distribution on the basis of the content of lipoproteins in TRF patients. Fluidity of the lipid bilayer of the red blood cell membrane was measured on Hitachi spectrofluorimeter according to the degree of eximerization of fluorescent pyrene. Dyslipidemia manifested itself as hyperlipidemia, hypertriglyceridemia, hypercholesterolemia and hyperphosphatidylcholinemia. The lipid profile of the red blood cell membranes was found to be deranged, which was evidenced by the reduced content of lipoproteins, total phospholipids, triglycerides, and cholesterol esters. In addition, there was a significant rise in the content of free cholesterol, lysolecithin and phosphatidyl ethanolamine. Impairment of lipid exchange between blood serum and the red blood cell membrane in TRF patients is under discussion. The changes in the lipid spectrum of the red blood cell membranes mirror their morphofunctional failure, supported by derangement of fluidity of the lipid bilayer of the red blood cell membrane. Both increase of viscosity of the lipid bilayer of the red blood cell membrane caused by a high level of cholesterol in the membrane and changes in the cholesterol/phospholipid ratio and reduction of the lipid bilayer viscosity related to the rise of the content of membrane lysolecithin in part of TRF patients were discovered. Hemodialysis influenced the lipid content of blood serum, producing no effect on the lipid spectrum of the red blood cells membrane.

Adult↗
PubMed1989

Analysis of gp74 expression by transformed rat fibroblasts from experimental pulmonary metastases following specific ricin A-chain immunotoxin therapy.

Ricin A chain immunotoxin (IT) 45-2D9-RTA mediates regression of spontaneous pulmonary metastases and lung colonies from K-ras transformed rat fibroblasts (TRF cells). However, residual metastases are frequently noted after IT therapy, and therefore, possible mechanisms mediating tumor cell escape were investigated. Individual lung colonies were dissected from lungs of BALB/c mice, and single-cell suspensions of fresh cells from short-term cultures (eight passages) were tested. Immunoperoxidase staining with 45-2D9 monoclonal antibody showed that stable loss of surface antigen by cells cultured from IT-treated mice did not occur after four injections of specific IT. Sensitivity to specific IT in vitro was equal for metastatic tumor cells from mice treated with either two or four doses of specific IT compared to cells from nonspecific IT-treated mice and to parental cells. Clones derived from metastases of IT-treated mice were not resistant to IT. Clones derived from metastases of specific IT-treated mice internalized bound antibody or IT at the same rate as untreated cells. Freshly disaggregated cells from specific IT-treated mice were as sensitive to specific IT as were cells from nonspecific IT-treated or untreated mice. Specific IT successfully mediated reduction of lung colonies derived from fresh suspensions of lung colony TRF cells from IT-treated mice. This reduction was equivalent to that seen for cells not previously exposed to specific IT. Immunoperoxidase stains of lung sections with 45-2D9 showed that colonies consisting entirely of unstained TRF cells were present in both specific IT and phosphate buffered saline-treated mice. There was a trend toward a higher percentage of antigen-negative colonies in mice treated with IT, although 9 days following specific IT therapy, greater than 80% of lung colonies expressed gp74 antigen. When TRF cells were grown on agar plugs, which promoted three-dimensional growth, groups of cells showing absence of immunoperoxidase staining with antibody to gp74 were identified during 2 weeks of growth. Thus, stability of antigen-negative variants is favored by three-dimensional growth conditions and the selective pressure of IT administration. Our results also suggest that impaired trafficking of IT to antigen-positive cells may also contribute to escape from IT therapy.

Animals↗
PubMed1988

Molecular properties and regulation of mRNA expression for murine T cell-replacing factor/IL-5.

We previously cloned cDNA for a T cell-replacing factor (TRF) that has been defined as a T cell-derived lymphokine that acts on activated B cells as a B cell growth and differentiation factor. Based on the diverse activities of rTRF on different target cells, we proposed that TRF be called IL-5. In this study, the molecular characteristics of TRF/IL-5 prepared by rDNA technology and TRF/IL-5 mRNA expression in various T cell lines and normal T cells have been studied. Specific immunoassay showed that rTRF/IL-5, which is transiently translated in vitro by rabbit reticulocyte lysate, has an apparent m.w. of 14,000. By contrast, active forms of rTRF/IL-5 translated in Xenopus oocytes has an apparent m.w. of 45,000 to 50,000 in the nonreducing condition and migrates to the m.w. of 25,000 to 30,000 under the reducing condition, indicating that active form of rTRF/IL-5 consists of dimer forms. The rTRF/IL-5 does not show detectable levels of IL-2, IL-3, and B-cell stimulatory factor 1 (IL-4) activities. Northern blot hybridization of poly (A)+ RNA from constitutively TRF-producing B151K12 T cell hybridoma revealed a single 1.7-kb band hybridizing to the cloned murine TRF/IL-5 cDNA. The expression of TRF/IL-5 mRNA in B151K12 was augmented by the stimulation with PMA plus calcium ionophore. In contrast, neither thymoma BW5147 nor IL-2-producing T cell hybridoma A55, both of which produced an undetectable level of TRF, expressed detectable levels of TRF/IL-5 mRNA. Stimulation of EL 4 and D9 cells with PMA and Con A, respectively, induced an increase in the levels of TRF/IL-5 mRNA expression accompanied by TRF/IL-5 production, whereas both cell lines did not show significant gene expression in the absence of the stimulation. In spleen cells from Mycobacterium tuberculosis-primed mice, significant expression of TRF/IL-5 mRNA was detected only when the cells were stimulated with relevant Ag, PPD. Normal spleen cells stimulated with Con A showed a significant, but approximately four-fold less expression of TRF/IL-5 mRNA. Molecular and functional properties of TRF/IL-5 will be discussed.

Animals↗
PubMed1987

[Molecular cloning of cDNAs encoding B-cell growth factors].

The proliferation and maturation of antigen-stimulated B cells are regulated by several soluble factors derived from macrophages and T cells. These soluble factors have been functionally divided into two groups; B-cell growth factor (BCGF) and B-cell differentiation factor (BCDF). However, this distinct classification and identification of B-cell factors should be reexamined after the recent cloning of cDNA encoding IgG1 induction factor (IL-4) from a 2.19 T-cell line. This factor induces not only an elevated IgG1 response in B cells activated by lipopolysaccharides but also hyper-Ia expression in B cells. IL-4 is identical to B-cell stimulating factor-1 (BSF-1) which induces DNA synthesis when given together with anti-IgM antibodies. Furthermore, this lymphokine has growth factor activities for both T and mast cells. Another well characterized B-cell factor is T-cell replacing factor (TRF). Although TRF was previously classified as a BCDF, a partially purified preparation of TRF was suggested to have BCGF II activity. The identity of TRF with BCGF II was proved by its cDNA cloning and the name IL-5 was proposed for this lymphokine.

Amino Acid Sequence↗
PubMed1987

Bioavailability of high-dose oral leucovorin.

Fifteen adult subjects comprised the study group; 2 were colon cancer patients. Total leucovorin (citrovorum factor; CF) doses of 200, 400, 800, and 1600 mg were equally subdivided and administered at 0, 1, 2, and 3 hours. Three of the subjects were fasting and the other 12 were not. Quantitation of serum L-CF by Pediococcus cerevisiae and total reduced folates (TRF) by radio-assay were performed in 10 samples from each subject drawn over a 12-hour period after initiation of CF dosing. The mean serum levels of L-CF remained greater than 0.1 microM at 3 hours and the TRF 3.5 microM at 5 hours, respectively, after termination of CF dosing in all subjects treated at the 800- and 1600-mg dose schedule. At all CF dosage schedules employed, peak serum concentrations were reached within 4 and 6 hours after initiation of oral CF. Peak TRF concentrations at the 200-, 400-, 800-, and 1600-mg doses were 3.42 +/- 0.65, 4.05 +/- 1.04, 4.81 +/- 0.14, and 5.11 +/- 1.81 microM, respectively. Peak L-CF levels at 200, 400, 800, and 1600 were 0.15 +/- 0.11, 0.21 +/- 0.14, 0.23 +/- 0.11, and 0.34 +/- 0.16 microM. Based upon these observations, the following conclusions were reached: 1) no significant differences were observed in serum concentrations of folates between the 800- and 1600-mg dose schedules; 2) at these doses serum concentrations of L-CF and TRF were achieved that warrant a phase I investigation of high-dose oral CF with standard dose FUra in patients with advanced colorectal carcinoma.

Administration, Oral↗
PubMed1979

IgG recruiting component (GRC): B cell-derived signal for IgG antibody synthesis.

The B cell-derived soluble factor that has been described as an IgG-recruiting component (GRC) was investigated to: a) ascertain whether it is governed by genetic constraints, b) determine what triggers its synthesis, and c) identify its cellular target. GRC has been shown to be unrestricted by histocompatibility barriers since it enhanced IgG antibody production in mice of diverse genetic backgrounds. Further, we report that eliminating IgG-bearing cells from B cells to be immunized in vitro allows T cells-replacing factor (TRF) to increase the number of IgM but not IgG PFC. Thus, TRF appears to act on IgM-bearing cells by expanding the IgM PFC number. Adding GRC 48 hr after the addition of TRF to such IgG-depleted cells caused expression of IgG PFC. Hence, B cells lacking IgG but possessing IgM surface immunoglobulins appear to be those that are acted upon by GRC. These data indicate that in whole splenic cell populations, GRC is derived from IgG-bearing B cells that are stimulated by antigen and a component in TRF.

Animals↗
PubMed1983

[Modulation of the expression of transferrin receptors by iron, hemin and protoporphyrin IX].

The expression of transferrin receptors in human leukemic cell lines was investigated. Our results have clearly shown that heme, iron and protoporphyrin-IX may modulate the expression of Trf receptors: iron and heme induce a decrease in the number of Trf receptors; in contrast protoporphyrin-IX elicited a significant increase in the number of Trf receptors. On the basis of these data we suggest that the intracellular concentration of iron, heme and protoporphyrin-IX may represent the main factor involved in the regulation of the expression of Trf receptors.

Animals↗
PubMed1982

Biochemical characterization of regulatory factors derived from T cell hybridomas and spleen cells. I. Separation of T cell growth factor and T cell replacing factor from granulocyte-macrophage colony-stimulating factor.

We describe the molecular characteristics of T cell growth factor (TCGF), T cell replacing factor (TRF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) produced by a T cell hybridoma after stimulation with concanavalin A (Con A). All three activities could be separated from Con A itself by ammonium sulfate precipitation. The TRF and TCGF activities had a m.w. of 35,000 to 40,000 on gel filtration in phosphate-buffered saline (PBS). Their m.w. were about 30,000 under dissociating conditions in guanidine hydrochloride and about 35,000 to 40,000 under disulfide reducing conditions, suggesting the molecule(s) lacked noncovalent or disulfide-linked subunit structure. GM-CSF had a m.w. of 25,000 to 30,000 by gel filtration in PBS and about 23,000 in guanidine hydrochloride. TRF and TCGF on the one hand and GM-CSF on the other could be distinguished by the criteria of m.w., relative heat sensitivity, and hydrophobic chromatography. TCGF could not be separated from TRF by any of these methods. In terms of all the above properties, factor derived from the T cell hybridoma and spleen cells appeared identical.

Animals↗
PubMed1994

Telomere shortening in renal cell carcinoma.

The ends of human chromosomes consist of a specialized structure, the telomere, composed of repeats of TTAGGG making up a total of 5-15 kilobase pairs, depending on age and proliferative activity of the tissue. The major function of telomeres is to provide stability to chromosomes and protect underlying unique coding sequences from degradation. There is a loss of telomeric sequences following every cell division estimated to be between 50 and 65 basepairs/cell division in human fibroblasts and embryonic kidney cells in vitro. This loss is due to the fact that DNA replication is incomplete for one strand at each telomere end. In lower eukaryotes there is a compensation mechanism provided by the enzyme telomerase, which is inactive in human somatic cells. Telomerase activation has also been detected in vitro immortalized human cells. In this study we analyzed renal cell carcinoma for the occurrence of telomere shortening using the probe (TTAGGG)4. Southern blots of HinfI-digested DNA revealed a shortening of mean telomere restriction fragment (TRF) length of 0.4 to 2.5 kilobase pairs in 2 or 3 intratumoral samples in all 10 tumors analyzed. No obvious intratumoral heterogeneity was found in mean TRF length values. However, heterogeneity was shown by the occurrence of at least two separate peak TRF values in 7 of 10 tumors, indicating the presence of different tumor cell clones. A conflicting observation was made when we evaluated the intensity of the hybridization signals, where three of the tumors showed an increase in hybridization signals despite concomitant TRF reduction. We found no correlation between tumor size and calculated tumor cell divisions undergone. In two tumors, the calculated cell division cycles were unrealistically low compared to the tumor size. These data suggest that telomerase activation might occur in human renal cell carcinoma.

Base Sequence↗