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Q Chang

Publications and source records attributed to Q Chang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Myocardial protection of warm blood cardioplegic induction during cardiopulmonary bypass.

In his prospective randomized clinical study, we evaluated the myocardial protection of warm blood cardioplegic induction and cold blood cardioplegic induction, respectively, during cardiopulmonary bypass. Twenty-eight adult patients who underwent valve replacement were randomly divided into two groups: group T (14 cases) received cold (6-8 degrees C) blood cardioplegic induction after ECG showed straight line induced by warm (35-37 degrees C) blood cardioplegia; whereas, group C (14 cases) received cold blood cardioplegic induction only. The effects of myocardial protection of both cardioplegic inductions were evaluated by clinical outcomes, myocardial biochemistry index (cardiac troponin T, cTnT), and myocardial automorphology. The ratio of myocardial auto resuscitation was significantly higher in group T (93%) than that in group C (50%). Only one case in group T (7%) and three cases in group C (21%) needed temporary pacemakers. No case in group T (0%) and five cases (36%) in group C received dopamine. The postoperative mechanical ventilation time and ICU stay time of group T were shorter than those of group C. Myocardial biochemistry indexplasma level of cTnT in group T was lower than that of group C immediately and 6 h after cardiopulmonary bypass. Myocardial morphology-group T had comparably better outcomes than group C. We concluded that warm blood cardioplegic induction during cardiopulmonary bypass, compared with cold blood cardioplegic induction, provides better myocardial protection.

Adult↗
PubMed2001

Oxidation rate in the preparation of polyferric sulfate coagulant.

The oxidation rate of ferrous sulfate was investigated in the preparation of polyferric sulfate(PFS) coagulant. It was proved that this reaction is zero order with respect to Fe2+, first order with respect to NO2(g) and first order with respect to the interface area between gas phase and liquid phase. If the partial pressure of NO2(g) in gas phase is increased or the interface area is increased, the time needed to complete the reaction will be decreased.

Ferrous Compounds↗
PubMed2001

Aortic root replacement.

OBJECTIVE: To report our operative experience with aortic root replacement in 231 patients with aortic root aneurysm and discuss the current indications, methods, and surgical techniques. METHODS: Between January 1994 and August 1999, a group of 231 consecutive patients underwent aortic root replacement at our hospital, with 13 being treated on an emergency basis. There were 189 men and 42 women, ranging in age from 14 to 69 years. The diameter of the aneurysm varied from 4.5 to 11 cm. Among this group, 145 had isolated aortic root aneurysms, 65 suffered from DeBakey type I aortic dissection, and the remaining 21 were diagnosed as having DeBakey type II aortic dissection. Aortic valve regurgitation occurred in all cases. Aortic root replacement was performed with composite valved graft in 229 patients, and in 2 patients the aortic valve was preserved. RESULTS: The hospital mortality rate was 3.03% (7 patients). Early complications included re-exploration for bleeding in 6 patients, pericardial effusion in 9, as well as cerebral infarction, pleural effusion, and pneumothorax in 2 patients each. One hundred and seventy-five patients (78.12%) were followed up, with a mean follow-up time of 15.7 +/- 13.1 months (range, 2 weeks to 65 months). One patient died from lower-limb embolism and renal dysfunction 3 months postoperatively. Three patients died from postoperative anticoagulation accidents. The preoperative and postoperative mean left ventricular end-diastolic diameters were significantly different (68.1 +/- 9.4 mm, range 54 to 112 mm; vs 54.8 +/- 8.2 mm, range 38 to 88 mm; P < 0.001). CONCLUSIONS: Once a diagnosis of acute aortic root dissecting aneurysm is made, the patient should undergo surgery as soon as possible if the general conditions permit. Aortic aneurysm without dissection or with chronic dissection should be operated if the diameter of the aneurysm is greater than 5 cm.

Adolescent↗
PubMed2001

[Surgical treatment of DeBakey type I and II aortic dissection].

OBJECTIVE: Aortic dissection is associated with significant mortality and morbidity. Effective methods to treat aortic disection are now available although these lesions still challenge the cardiovascular surgeon. METHODS: From January 1994 to January 2000. 131 patients with DeBakey I, II type aortic dissection underwent surgical treatment. Operations were performed under cardiopulmonary bypass in 59 patients. Hypothermic circulatory arrest was used in 15 patients. Hypothermic circulatory arrest and selective cerebral perfusion was used in 57 patients. A graft replacement of ascending aorta and partial aortic arch was performed in 25 patients, ascending aorta and total aortic arch in 10. 83 patients underwent the Bentall procedure. The Bentall procedure and total aortic arch replacement were performed in 3 patients, the Wheats operation in 4. 4 patients underwent the elephant trunk techniques and 2 patients with the elephant trunk techniques and the Bentall procedures. RESULTS: There were 4 deaths within 30 days after surgery with an operative mortality of 3.05%, and 3 neurological dysfunction undergone hypothermic circulatory arrest. They were recovered within 1 week. CONCLUSION: The operative technique is difficult. Selective cerebral perfusion can provide available protection during surgery of aortic dissection. It prolongs the time allowed to performed the aortic repair.

Adolescent↗
PubMed2001

Monitoring of antegrade selective cerebral perfusion for aortic arch surgery with transcranial Doppler ultrasonography and near-infrared spectroscopy.

OBJECTIVE: To evaluate the safety and efficacy of antegrade selective cerebral perfusion (ASCP) during aortic arch surgery as a means of extending the safe period of systemic circulatory arrest using multimodality neuromonitoring to objectively quantify the physiologic responses. METHODS: In twenty-two patients (all less than age 60) scheduled for repair of an aortic arch aneurysm, preoperative verification of effective collateral perfusion through both the carotid and vertebrobasilar arterial systems was documented with transcranial Doppler ultrasonography (TCD). During cardiopulmonary bypass, the sole arterial inflow from the pump was via the right subclavian artery. The magnitude of ASCP was quantified by TCD using peak middle cerebral artery velocity, while flow adequacy was measured by continuous regional cerebrovenous oxygen saturation (rSO2) using dual-wavelength spatially resolved near-infrared spectroscopy. RESULTS: All patients experienced an uneventful recovery. Flow in the middle cerebral artery became undetectable at ASCP < 5 ml.kg-1.min-1, so adjustments from a 15-20 ml.kg-1.min-1 baseline were used to maintain rSO2 above 50%. Furthermore, ASCP flow was highly correlated (P < 0.01) with both peak middle cerebral artery velocity and rSO2(r = 0.86 and 0.96, respectively). CONCLUSION: Neuromonitoring guided ASCP may be expected to extend the safe period and is at least partly responsible for the absence of neurologic complications in this patient cohort.

Adolescent↗
PubMed2000

Phosphorylation of human glutamine:fructose-6-phosphate amidotransferase by cAMP-dependent protein kinase at serine 205 blocks the enzyme activity.

Glutamine:fructose-6-phosphate amidotransferase (GFAT) is the rate-limiting enzyme in glucosamine synthesis. Prior studies from our laboratory indicated that activation of adenylate cyclase was associated with depletion of O-GlcNAc modification. This finding and evidence that human GFAT (hGFAT) might be regulated by cAMP-dependent protein kinase (PKA) led us to investigate the role of PKA in hGFAT function. We confirmed that adenylate cyclase activation by forskolin results in diminished O-GlcNAc modification of several cellular proteins which can be overcome by exposure of the cells to glucosamine but not glucose, suggesting the PKA activation results in depletion of UDP-GlcNAc for O-glycosylation. To determine if GFAT is indeed regulated by PKA, we expressed the active form of the enzyme using a vaccinia virus expression system and showed that the activity of the enzyme was to decrease to undetectable levels by PKA phosphorylation. We mapped the PKA phosphorylation sites with the aid of matrix-assisted laser desorption ionization mass spectroscopy and showed that the protein was stoichiometrically phosphorylated at serine 205 and also phosphorylated, to a lesser extent at serine 235. Mutagenesis studies indicated that the phosphorylation of serine 205 by PKA was necessary for the observed inhibition of enzyme activity while serine 235 phosphorylation played no observable role. The activity of GFAT is down-regulated by cAMP, thus placing regulation on the hexosamine pathway that is in concert with the energy requirements of the organism. During starvation, hormones acting through adenylate cyclase could direct the flux of glucose metabolism into energy production rather than into synthetic pathways that require hexosamines.

Colforsin↗
PubMed2000

High-dose porcine hematopoietic cell transplantation combined with CD40 ligand blockade in baboons prevents an induced anti-pig humoral response.

BACKGROUND: In pig-to-primate organ transplantation, hyperacute rejection can be prevented, but the organ is rejected within days by acute vascular rejection, in which induced high-affinity anti-Gal alpha1-3Gal (alphaGal) IgG and possibly antibodies directed against new porcine (non-alphaGal) antigenic determinants are considered to play a major role. We have explored the role of an anti-CD40L monoclonal antibody in modifying the humoral response to porcine hematopoietic cells in baboons pretreated with a nonmyeloablative regimen. METHODS: Porcine peripheral blood mobilized progenitor cells obtained by leukapheresis from both major histocompatibility complex-inbred miniature swine (n=7) and human decay-accelerating factor pigs (n=3) were transplanted into baboons. Group 1 baboons (n=3) underwent whole body (300 cGy) and thymic (700 cGy) irradiation, T cell depletion with ATG, complement depletion with cobra venom factor, short courses of cyclosporine, mycophenolate mofetil, porcine hematopoietic growth factors, and anti-alphaGal antibody depletion by immunoadsorption before transplantation of high doses (2-4 x 10(10)/cells/kg) of peripheral blood mobilized progenitor cells. In group 2 (n=5), cyclosporine was replaced by eight doses of anti-CD40L monoclonal antibodies over 14 days. The group 3 baboons (n=2) received the group 1 regimen plus 2 doses of anti-CD40L monoclonal antibodies (on days 0 and 2). RESULTS: In group 1, sensitization to alphaGal (with increases in IgM and IgG of 3- to 6-fold and 100-fold, respectively) and the development of antibodies to new non-alphaGal porcine antigens occurred within 20 days. In group 2, no sensitization to alphaGal or non-alphaGal determinants was seen, but alphaGal-reactive antibodies did return to their pre- peripheral blood mobilized progenitor cells transplant levels. In group 3, attenuated sensitization to alphaGal antigens was seen after cessation of cyclosporine and mycophenolate mofetil therapy at 30 days (IgM 4-fold, IgG 8-30-fold), but no antibodies developed against new porcine determinants. In no baboon did anti-CD40L monoclonal antibodies prevent sensitization to its own murine antigens. CONCLUSIONS: We believe these studies are the first to consistently demonstrate prevention of a secondary humoral response after cell or organ transplantation in a pig-to-primate model. The development of sensitization to the murine elements of the anti-CD40L monoclonal antibodies suggests that nonresponsiveness to cell membrane-bound antigen (e.g., alphaGal) is a specific phenomenon and not a general manifestation of immunological unresponsiveness. T cell costimulatory blockade may facilitate induction of mixed hematopoietic chimerism and, consequently, of tolerance to pig organs and tissues.

Animals↗
PubMed2000

A pneumococcal capsular polysaccharide vaccine induces a repertoire shift with increased VH3 expression in peripheral B cells from human immunodeficiency virus (HIV)-uninfected but not HIV-infected persons.

The molecular mechanism of pneumococcal vaccine failure in human immunodeficiency virus (HIV)-infected persons is not fully understood. A polymerase chain reaction ELISA was used to determine the proportion of peripheral IgG, IgA, and IgM CD19-positive B cells expressing 6 immunoglobulin heavy-chain variable region (VH) subgroups before and 7 days after pneumococcal vaccination of 12 HIV-infected and 12 HIV-uninfected subjects. Significant postvaccination increases in the expression of the VH3 subgroup by IgG and IgA and a greater serologic response to vaccination were observed in the HIV-uninfected group. In contrast, the HIV-infected group had reduced prevaccination IgG VH3 and a postvaccination increase in IgG VH5. These results demonstrate that pneumococcal vaccination changes the pattern of B cell VH gene expression and support the concept that aberrant VH3 expression may translate into a poor antipneumococcal response in the setting of HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed2000

The effect of protein kinase C activation on colonic epithelial cellular integrity.

We have investigated whether activation of protein kinase C has a direct cytotoxic effect on colonic mucosal epithelial cells and whether oxidant-induced damage to colonocytes is mediated by activation of cellular protein kinase C. Incubation of freshly harvested cells from rat colon with the protein kinase C activator, phorbol 12-myristate, resulted in a concentration-dependent increase in the extent of cell injury. Phorbol 12-myristate acetate (0.1-10 microM) also increased cellular protein kinase C activity and this was reduced significantly by treating cells with the antagonists staurosporine or 2-[1-(3-dimethylaminopropyl)-indol-3-yl]3-(-indol-3-yl)maleimide (GF 109203X; 10 microM). Phorbol 12-myristate acetate treatment also resulted in increased translocation of proteins for protein kinase C isoforms alpha, delta and epsilon from cytosol to membrane particulate fractions. The antagonists reduced the extent of cell damage in response to phorbol 12-myristate acetate. Furthermore, cell injury in response to the phorbol acetate was also inhibited by the addition of the oxidant scavengers, superoxide dismutase or catalase to the cell suspension. Addition of H(2)O(2) to the incubation medium (0.1-100 microM) resulted in an increase in cellular protein kinase C activity, an increase in the expression of the alpha, beta and zeta isoforms and a reduction in cell integrity. The cellular damaging actions of H(2)O(2) were significantly reduced by the protein kinase C antagonists, staurosporine or 2-[1-(3-dimethylaminopropyl)-indol-3-yl]-3-(-indol-3-yl)maleimide (GF 109203X). These findings suggest that protein kinase C activation results in colonic cellular injury and this damage is mediated, at least in part, by release of reactive oxidants. Furthermore, oxidant-mediated damage to these cells also involves protein kinase C activation.

Animals↗
PubMed2000

Cytokine-mobilized peripheral blood progenitor cells for allogeneic reconstitution of miniature swine.

BACKGROUND: Because of the relative ease of acquisition, increased yield, and improved engraftment characteristics, mobilized peripheral blood progenitor (stem) cells (PBSCs) have recently become the preferred source for hematopoietic stem cell transplantation. In our laboratory, procurement of a megadose of PBSCs is necessary for on-going studies evaluating non-myelosuppressive transplant regimens for the induction of mixed chimerism and allograft tolerance. To exploit hematopoietic growth factor synergy, we have sought to combine growth factors with proven utility to improve PBSC mobilization and maximize our PBSC procurement through an automated collection procedure. METHODS: Mobilization characteristics of PBSCs were determined in 2-5-month-old miniature swine. Animals received either swine recombinant stem cell factor (pSCF, 100 microg/kg) and swine recombinant interleukin 3 (pIL-3, 100 microg/kg), administered intramuscularly for 8 days, or pSCF, pIL-3, and human recombinant granulocyte-colony stimulating factor (hG-CSF), at 10 microg/kg. Leukapheresis was performed beginning on day 5 of cytokine treatment and continued daily for 3 days. RESULTS: Collection of PBSCs from cytokine-mobilized animals via an automated leukapheresis procedure demonstrated a 10-fold increase in the number of total nucleated cells (TNC) (20-30 x 10(10) TNC) compared to bone marrow harvesting (2-3 x 10(10) total TNC). A more rapid rise in white blood cells (WBCs) was seen after administration of all three cytokines compared to pSCF and pIL-3 alone. An increase in colony-forming unit granulocyte-macrophage frequency measured daily from peripheral blood during cytokine treatment, was seen with the addition of hG-CSF to pSCF/pIL-3 correlating well with the rise in WBCs. Similarly, the addition of hG-CSF demonstrated a notable increase in the median progenitor cell yield from the 3-day leukapheresis procedure. Cytokine-mobilized PBSCs were capable of hematopoietic reconstitution. PBSCs mobilized with pSCF/pIL-3 were infused into an SLA-matched recipient conditioned with cyclophosphamide (50 mg/kg) and total body irradiation 1150 cGy. Neutrophil and platelet engraftment occurred on days 5 and 7, respectively, with minimal evidence of graft-versus-host disease. Complete donor chimerism has been demonstrated 331 days after transplant. CONCLUSIONS: Our preliminary results show that in this well-defined miniature swine model, recombinant swine cytokine combinations (pSCF, pIL-3 with or without hG-CSF) successfully mobilize a high yield of progenitor cells for allogeneic transplantation. Furthermore, these cytokine-mobilized PBSCs demonstrate the potential to reconstitute hematopoiesis and provide long-term engraftment in miniature swine.

Animals↗
PubMed2000

Nerve injury induces gap junctional coupling among axotomized adult motor neurons.

Neonatal spinal motor neurons are electrically and dye-coupled by gap junctions, but coupling is transient and disappears rapidly after birth. Here we report that adult motor neurons become recoupled by gap junctions after peripheral nerve injury. One and 4-6 weeks after nerve cut, clusters of dye-coupled motor neurons were observed among axotomized, but not control, lumbar spinal motor neurons in adult cats. Electrical coupling was not apparent, probably because of the electrotonic distance between dendrodendritic gap junctions and the somatic recording location. Analyses of gap junction protein expression in cat and rat showed that the repertoire of connexins expressed by normal adult motor neurons, Cx36, Cx37, Cx40, Cx43, and Cx45, was unchanged after axotomy. Our results suggest that the reestablishment of gap junctional coupling among axotomized adult motor neurons may occur by modulation of existing gap junction proteins that are constitutively expressed by motor neurons. After injury, interneuronal gap junctional coupling may mediate signaling that maintains the viability of axotomized motor neurons until synaptic connections are reestablished within their targets.

Action Potentials↗
PubMed2000

Alterations in protein kinase C isoforms in experimentally-induced colitis in the rat.

BACKGROUND: Although protein kinase C (PKC) isoenzymes have been implicated as mediators for multiple physiological processes, PKC also mediates cellular and intestinal mucosal injury. We have investigated the expression of the isoenzymes, PKCalpha, PKCdelta, PKCepsilon and PKCzeta in colonic mucosal tissue from TNBS-treated and HLA-B27 spontaneous colitis animals. METHODS: Colonic mucosal samples were taken at various times (2 h-14 d) after instillation of TNBS (75 mg/kg in 50% ethanol) or from HLA-B27 rats at 16-18 weeks of age. Tissues were homogenized and separated into membrane and cytosolic fractions by centrifugation. PKC activity was measured radioenzymatically. PKC protein for isoforms alpha, delta, epsilon and delta was assessed by Western blot while corresponding mRNA was analyzed by RT-PCR. RESULTS: PKC activity increased in cytosolic and membrane fractions by 1d after TNBS and returned to normal by d3. PKCalpha protein was translocated from cytosol to membrane by 2 h after TNBS followed by down-regulation until d3. Increases in PKCdelta, PKCepsilon and PKCzeta protein occurred initially in membrane fractions as early as 2 h after TNBS. Increases in cytosolic protein occurred at later times after induction of colitis. Protein levels for all isoenzymes remained increased up to 7d after TNBS. RT-PCR revealed that mRNA for PKCalpha decreased while PKC mRNA increased correspondingly with their respective protein levels. In HLA-B27 rats, protein levels for all isoforms were less than was detected in normal colonic tissue. CONCLUSIONS: The early increase in gene expression and protein levels for PKCalpha and zeta suggest that these isozymes may play roles in an acute model of colitis induced by TNBS. In contrast, the increase in PKCdelta and epsilon protein was not associated with mRNA changes suggesting that these isozymes are not similarly regulated in the inflamed colonic mucosa. In a chronic model of experimental colonic inflammation (HLA-B27), all of these isoforms appeared to be down-regulated.

Animals↗
PubMed2000

Esterification of polyunsaturated fatty acids by various forms of immobilized lipase from Rhizomucor miehei.

Ethyl esterification specificity of a lipase from Rhizomucor miehei for polyunsaturated fatty acids (PUFA) was compared at 1 and 100 mM to study molecular recognition of PUFA. The chemical shift of methylene adjacent to carboxyl groups in the nuclear magnetic resonance spectrum of docosahexaenoic acid (DHA) in ethanol moved to a lower magnetic field as the concentration of DHA increased, suggesting that the degree of dissociation of DHA decreased. Specificity constants or apparent second-order rate constants (Vmax/Km or catalytic power) for 1 mM esterification by immobilized lipases were higher than the native lipase. Immobilized hydrophobic carrier of low mass transfer resistance for the esterification substrate may improve maximal velocity and affinity for the substrate. Higher specificity constants for 1 mM substrates were observed using immobilized lipases fixed on an anion exchange resin with glutaraldehyde and on a cation exchange carrier with carbodiimide. Activity yields measured with 1 mM PUFA substrate were high. For the substrates at a concentration of 100 mM, higher specific constants with these bifunctional reagents were not observed but higher activity yields were found.

Anions↗
PubMed2000

Aortic root replacement by ministernotomy: technique and potential benefit.

BACKGROUND: Although minimally invasive surgical procedures have aroused much interest in cardiac surgery, difficulty still exists with its application in most of the operations on great arteries. This report summarizes our initial experience of aortic root replacement by a superior ministernotomy in terms of operative indications, operative techniques, and potential benefits. METHODS: Between July 1999 and September 1999, 8 patients who were diagnosed with Marfan syndrome with aortic valve regurgitation underwent aortic root replacements with composite grafts. Clinical characteristics, in-hospital outcomes, and postoperative stay of these patients were compared with data of patients who had undergone Bentall procedure by standard median sternotomy from January to September 1999. RESULTS: There was no death in either group of patients. Demographics were similar between the two groups of patients. In the mini-incision group, the mediastinal drainage was significantly less than the standard incision group. The mean operating time was significantly longer than that in the standard incision group. The cardiopulmonary bypass time and aortic cross-clamping time were similar in both groups of patients. The mean intubation time, postoperative blood transfusion amount, duration of intensive care unit stay and postoperative hospital stay were less than that of the standard incision group; however, they all showed no statistical significant difference. CONCLUSIONS: Aortic root replacement by a superior ministernotomy in cardiopulmonary bypass with cannulas through the femoral artery and femoral vein or right atrium is a safe, reliable procedure with excellent exposure. The procedure provides a potential benefit of less trauma, quick recovery, and reduction of mediastinal drainage and reduction of blood transfusion.

Adult↗
PubMed2000

Gap junctional communication among developing and injured motor neurons.

The functional significance of gap junctional coupling among neurons is poorly understood. We are studying gap junctions among spinal motor neurons as a model for understanding roles of interneuronal gap junctional communication during development and after injury. Electrical and dye coupling is widespread among neonatal motor neurons but is transient, disappearing by the end of the first postnatal week. Reverse transcription polymerase chain reaction (RT-PCR) analysis, in situ hybridization and immunohistochemistry show that five rodent connexins, Cx36, Cx37, Cx40, Cx43 and Cx45, are expressed by developing motor neurons. These gap junction proteins remain expressed in some motor neurons through adult life, with the exception of Cx40, whose expression appears to decrease shortly after birth. After nerve injury in adult animals, motor neurons once again become dye coupled, and this appears to occur without dramatic changes in connexin expression. The transient gap junctional coupling present among developing motor neurons, which is re-capitulated after axotomy, may mediate electrical or biochemical signaling that shapes neuronal function.

Age Factors↗
PubMed2000

Citrate enhances olfactory receptor responses and triggers oscillatory receptor activity in the channel catfish.

Citrate, a normal constituent of cellular metabolism, in a binary mixture with an amino acid enhanced asynchronous olfactory receptor responses in the channel catfish, Ictalurus punctatus. In addition, high concentrations of either citrate (> or =3 mM) alone or an amino acid (> or =0.1 mM) in a binary mixture with citrate (> or =1 mM) triggered synchronized voltage oscillations of olfactory receptor neurons (ORNs) known as "peripheral waves" (PWs). Binary mixtures containing lower concentrations of an amino acid also triggered PW activity if the concentration of citrate in the mixture was increased. Both the enhancement of asynchronous activity and the generation of PW activity were the result of citrate chelating calcium, which lowers the surface potential of ORNs making them hyperexcitable. These effects of citrate are replicated by EGTA. Inactivation of the chelating ability of citrate and EGTA with 1 mM calcium chloride, barium chloride, or strontium chloride abolished both the enhancement of asynchronous olfactory responses and PW activity, while not affecting olfactory receptor responses to the amino acids alone.

Action Potentials↗
PubMed2000

Relationship of telomeres and p53 in aging bovine corneal endothelial cell cultures.

PURPOSE: To demonstrate a relationship between telomere lengths and levels of p53 in cultured bovine corneal endothelial cells (CECs) during aging. METHODS: Bovine CECs were grown and aged as long-term cultures. Telomere lengths were determined directly on gels with 32P probes after treatment of isolated DNA with RsaI and HinfI. Protein p53 was determined using an enzyme-linked immunosorbent sandwich assay. Cellular aging and the development of replicative senescence were monitored by the appearance of senescent morphology and the beta-galactosidase assay. RESULTS: Bovine CEC telomeres lost 4 kb (from 12.8 to 8.8 kb) over 1 year (89 population doublings [PDs]). The p53 levels in bovine CECs were initially small (approximately 60 pg/million cells), but rose 3.5-fold by culture age of 260 days (64 PDs). On initiation, cultured bovine CECs did not stain for the senescent marker beta-galactosidase. However, these cells stained at 89 PDs and senescent morphology was observed in the cultures at 64 PDs. CONCLUSIONS: The data indicate an inverse relationship between telomere lengths (decreasing) and levels of p53 (increasing) in bovine CECs during aging. These properties may influence the ability of these cells to divide as they enter into replicative senescence.

Animals↗