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1.
Physiol Res ; 72(3): 280-286, 2023 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-37449742

RESUMO

Chronic venous disease (CVD) is a vascular disorder in which blood return is severely compromised and CVD is usually characterized by venous hypertension. Along with obesity and diabetes mellitus, CVD is one of the most common civilization diseases. In general, the estimated prevalence of CVD ranges from 60-80 %. Early diagnosis and adequate treatment are important for preventing progression to more severe stages of the disease like venous leg ulcers. Clinical manifestations of CVD in initial stages of the disease are often asymptomatic. However, as CVD progresses, symptoms begin to develop. Treatment of CVD could be divided into conservative and surgical. Conservative therapy consists of compression, pharmacological treatment and lifestyle change. In cases where conservative therapy is ineffective, surgical or endovascular treatment may be required. The intersections between diabetes mellitus (DM) and CVD are not to be underestimated. CVD and DM have often the same risk factors. Symptoms of CVD can be modified by late complications of DM, but the incidence of different CVD degrees seems to be the same as in diabetics as in non-diabetics population. We are particularly concerned in diabetics about worse compliance with treatment due to their often-poorer adherence to treatment of DM and lifestyle changes. Moreover, there exist a higher risk of CVD and peripheral arterial disease in diabetics patients. Patients with CVD should always be inspected for the presence of DM, considering its presence can have a bearing on CVD symptoms, diagnostic procedures, and therapeutic strategies.


Assuntos
Doenças Cardiovasculares , Diabetes Mellitus , Doenças Vasculares , Humanos , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/terapia , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiologia , Diabetes Mellitus/terapia , Fatores de Risco , Doença Crônica
2.
J Diabetes Res ; 2022: 3954740, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35450383

RESUMO

Introduction: Autologous cell therapy (ACT) is one of the last options for limb salvage in patients with chronic limb-threatening ischemia (CLTI) and diabetic foot ulcers (DFU). However, some patients may still undergo a major amputation even after ACT, but the risk factors for this are not known. Therefore, the aim of our study was to assess the risk factors for major amputation in patients with CLTI and DFU during a 2-year follow-up after ACT. Methods: One hundred and thirteen patients after ACT were included in our study and divided into two groups: Group 1 with major amputation (AMP; n = 37) and Group 2 without amputation (nAMP, n = 76). The risk factors for major amputation were evaluated before ACT and included factors relating to the patient, the DFU, and the cell product. Results: The AMP group had significantly higher C-reactive protein (CRP) levels compared to the nAMP group (22.7 vs. 10.7 mg/L, p = 0.024). In stepwise logistic regression, independent predictors for major amputation were mutation of the gene for methylenetetrahydrofolate reductase (MTHFR) with heterozygote and homozygote polymorphism 1298 (OR 4.33 [95% CI 1.05-17.6]), smoking (OR 3.83 [95% CI 1.18-12.5]), and CRP > 10 mg/L (OR 2.76 [95% CI 0.93-8.21]). Lower transcutaneous oxygen pressure (TcPO2) values were observed in AMP patients compared to the nAMP group at one month (24.5 vs. 33.2, p = 0.012) and at 3 months (31.1 vs. 40.9, p = 0.009) after ACT. Conclusion: Our study showed that the risk for major amputation after ACT in patients with CLTI and DFU is increased by the presence of MTHFR heterozygote and homozygote gene mutations, smoking, and higher CRP at baseline. Lower TcPO2 at one and 3 months after ACT may also have a predictive value. Therefore, it is necessary to stop smoking before ACT, treat any infection, and, above all, consider antiaggregation or anticoagulant treatment after the procedure.


Assuntos
Diabetes Mellitus , Pé Diabético , Monofosfato de Adenosina , Amputação Cirúrgica , Terapia Baseada em Transplante de Células e Tecidos , Isquemia Crônica Crítica de Membro , Pé Diabético/cirurgia , Humanos , Isquemia/cirurgia , Salvamento de Membro , Estudos Retrospectivos , Fatores de Risco , Resultado do Tratamento , Cicatrização
3.
Int J Low Extrem Wounds ; : 15347346211052155, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34723678

RESUMO

Diabetic foot (DF) can develop in diabetic patients after organ transplantation (Tx) due to several factors including peripheral arterial disease (PAD), diabetic neuropathy and inappropriate DF prevention. Aim: To assess the occurrence of DF and associated risk factors in transplant patients. Methods: Fifty-seven diabetic patients were enrolled as part of this prospective study. All patients underwent organ Tx (01/2013-12/2015) and were followed up for minimum of 12 months up to a maximum of 50 months. Over the study period we evaluated DF incidence and identified a number of factors likely to influence DF development, including organ function, presence of late complications, PAD, history of DF, levels of physical activity before and after Tx, patient education and standards of DF prevention. Results: Active DF developed in 31.6% (18/57) of patients after organ Tx within 11 months on average (10.7 ± 8 months). The following factors significantly correlated with DF development: diabetes control (p = .0065), PAD (p<0.0001), transcutaneous oxygen pressure (TcPO2;p = .01), history of DF (p = .0031), deformities (p = .0021) and increased leisure-time physical activity (LTPA) before Tx (p = .037). However, based on logistic stepwise regression analysis, the only factors significantly associated with DF during the post-transplant period were: PAD, deformities and increased LTPA. Education was provided to patients periodically (2.6 ± 2.5 times) during the observation period. Although 94.7% of patients regularly inspected their feet (4.5 ± 2.9 times/week), only 26.3% of transplant patients used appropriate footwear. Conclusions: Incidence of DF was relatively high, affecting almost 1/3 of pancreas and kidney/pancreas recipients. The predominant risk factors were: presence of PAD, foot deformities and higher LTPA before Tx. Therefore, we recommend a programme involving more detailed vascular and physical examinations and more intensive education focusing on physical activity and DF prevention in at-risk patients before transplantation.

4.
Physiol Res ; 68(4): 559-566, 2019 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-31177796

RESUMO

Autologous cell therapy (ACT) is a new treatment method for diabetic patients with critical limb ischemia (CLI) not eligible for standard revascularization. After intramuscular injection of bone marrow-derived mononuclear cells local arteriogenesis in the ischemic tissue occurs. Studies assessing visualization of this therapeutic vasculogenesis after ACT by novel imaging techniques are lacking. The aim of our study was to assess the effect of ACT on possible metabolic changes and perfusion of critically ischemic limbs using (31)P magnetic resonance spectroscopy ( (31)P MRS) and its possible correlation with changes of transcutaneous oxygen pressure (TcPO(2)). Twenty-one patients with diabetes and no-option CLI treated by ACT in our foot clinic over 8 years were included in the study. TcPO(2) as well as rest (phosphocreatine, adenosine triphosphate and inorganic phosphate) and dynamic (mitochondrial capacity and phosphocreatine recovery time) (31)P-MRS parameters were evaluated at baseline and 3 months after cell treatment. TcPO(2) increased significantly after 3 months compared with baseline (from 22.4±8.2 to 37.6±13.3 mm Hg, p=0.0002). Rest and dynamic (31)P MRS parameters were not significantly different after ACT in comparison with baseline values. Our study showed a significant increase of TcPO(2) on the dorsum of the foot after ACT. We did not observe any changes of rest or dynamic (31)P MRS parameters in the area of the proximal calf where the cell suspension has been injected into.


Assuntos
Transplante de Medula Óssea/métodos , Isquemia/diagnóstico por imagem , Isquemia/terapia , Perna (Membro)/irrigação sanguínea , Perna (Membro)/diagnóstico por imagem , Espectroscopia de Ressonância Magnética/métodos , Seguimentos , Humanos , Isquemia/metabolismo , Perna (Membro)/patologia , Radioisótopos de Fósforo , Transplante Autólogo/métodos
5.
Diabet Med ; 36(9): 1133-1140, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31077439

RESUMO

AIM: To assess the impact of autologous cell therapy on critical limb ischaemia in people with diabetes and diabetic kidney disease. METHODS: A total of 59 people with diabetes (type 1 or type 2) and critical limb ischaemia, persisting after standard revascularization, were treated with cell therapy in our foot clinic over 7 years; this group comprised 17 people with and 42 without severe diabetic kidney disease. The control group had the same inclusion criteria, but was treated conservatively and comprised 21 people with and 23 without severe diabetic kidney disease. Severe diabetic kidney disease was defined as chronic kidney disease stages 4-5 (GFR <30 ml/min/1.73 m²). Death and amputation-free survival were assessed during the 18-month follow-up; changes in transcutaneous oxygen pressure were evaluated at 6 and 12 months after cell therapy. RESULTS: Transcutaneous oxygen pressure increased significantly in both groups receiving cell therapy compared to baseline (both P<0.01); no significant change in either of the control groups was observed. The cell therapy severe diabetic kidney disease group had a significantly longer amputation-free survival time compared to the severe diabetic kidney disease control group (hazard ratio 0.36, 95% CI 0.14-0.91; P=0.042); there was no difference in the non-severe diabetic kidney disease groups. The severe diabetic kidney disease control group had a tendency to have higher mortality (hazard ratio 2.82, 95% CI 0.81-9.80; P=0.062) than the non-severe diabetic kidney disease control group, but there was no difference between the severe diabetic kidney disease and non-severe diabetic kidney disease cell therapy groups. CONCLUSIONS: The present study shows that autologous cell therapy in people with severe diabetic kidney disease significantly improved critical limb ischaemia and lengthened amputation-free survival in comparison with conservative treatment; however, the treatment did not influence overall survival.


Assuntos
Terapia Baseada em Transplante de Células e Tecidos/métodos , Pé Diabético/terapia , Nefropatias Diabéticas/complicações , Pé/irrigação sanguínea , Isquemia/terapia , Salvamento de Membro/métodos , Idoso , Amputação Cirúrgica/estatística & dados numéricos , Estudos de Casos e Controles , Estado Terminal/epidemiologia , Estado Terminal/terapia , República Tcheca/epidemiologia , Pé Diabético/complicações , Pé Diabético/epidemiologia , Nefropatias Diabéticas/epidemiologia , Nefropatias Diabéticas/patologia , Nefropatias Diabéticas/terapia , Feminino , Seguimentos , Pé/patologia , Humanos , Isquemia/complicações , Isquemia/epidemiologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Índice de Gravidade de Doença , Transplante Autólogo , Resultado do Tratamento , Procedimentos Cirúrgicos Vasculares/métodos
6.
Physiol Res ; 67(4): 583-589, 2018 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-29750878

RESUMO

Perfusion scintigraphy with technetium-99-methoxy-isobutyl-isonitrile ((99m)Tc-MIBI) is often used for assessing myocardial function but the number of studies concerning lower limb perfusion is limited. The aim of our study was to assess whether (99m)Tc-MIBI was an eligible method for evaluation of the effect of cell therapy on critical limb ischemia (CLI) in diabetic patients. (99m)Tc-MIBI of calf muscles was performed before and 3 months after autologous cell therapy (ACT) in 24 diabetic patients with CLI. Scintigraphic parameters such as rest count and exercising count after a stress test were defined. These parameters and their ratios were compared between treated and untreated (control) limbs and with changes in transcutaneous oxygen pressure (TcPO(2)) that served as a reference method. The effect of ACT was confirmed by a significant increase in TcPO(2) values (p<0.001) at 3 months after ACT. We did not observe any significant changes of scintigraphic parameters both at rest and after stress 3 months after ACT, there were no differences between treated and control limbs and no association with TcPO(2) changes. Results of our study showed no significant contribution of (99m)Tc-MIBI of calf muscles to the assessment of ACT in diabetic patients with CLI over a 3-month follow-up period.


Assuntos
Terapia Baseada em Transplante de Células e Tecidos/tendências , Diabetes Mellitus Tipo 2/diagnóstico por imagem , Diabetes Mellitus Tipo 2/terapia , Pé Diabético/diagnóstico por imagem , Pé Diabético/terapia , Imagem de Perfusão/métodos , Idoso , Feminino , Humanos , Perna (Membro)/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Tecnécio Tc 99m Sestamibi , Transplante Autólogo/tendências
7.
Rozhl Chir ; 95(7): 257-61, 2016.
Artigo em Tcheco | MEDLINE | ID: mdl-27523173

RESUMO

UNLABELLED: Adequate stabilization and off-loading of the lower limb is an integral part of postoperative care for patients with the diabetic foot. Off-loading can accelerate the healing process and reduce the number of complications and reoperations. The newly introduced method of the performance of removable contact splints (modified contact removable casts) seems to fulfil a number of requirements for stabilization and off-loading devices - the method is safe and can actually reduce the healing time and the number of reoperations in patients with the diabetic foot. KEY WORDS: diabetic foot - off-loading - splints.


Assuntos
Moldes Cirúrgicos , Pé Diabético/cirurgia , Cuidados Pós-Operatórios/métodos , Contenções , Cicatrização , Pé Diabético/reabilitação , Humanos , Suporte de Carga
8.
Diabetes Metab Res Rev ; 29(5): 369-76, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23390092

RESUMO

BACKGROUND: The aim of our study was to compare the effect of bone marrow mononuclear cell and peripheral blood progenitor cell therapies in patients with diabetic foot disease and critical limb ischaemia unresponsive to revascularization with conservative therapy. METHODS: Twenty-eight patients with diabetic foot disease (17 treated by bone marrow cells and 11 by peripheral blood cell) were included into an active group and 22 patients into a control group without cell treatment. Transcutaneous oxygen pressure and rate of major amputation, as the main outcome measures, were compared between bone marrow cells, peripheral blood cell and control groups over 6 months; both cell therapy methods were also compared by the characteristics of cell suspensions. Possible adverse events were evaluated by changes of serum levels of angiogenic cytokines and retinal fundoscopic examination. RESULTS: The transcutaneous oxygen pressure increased significantly (p < 0.05) compared with baseline in both active groups after 6 months, with no significant differences between bone marrow cells and peripheral blood cell groups; however, no change of transcutaneous oxygen pressure in the control group was observed. The rate of major amputation by 6 months was significantly lower in the active cell therapy group compared with that in the control group (11.1% vs. 50%, p = 0.0032), with no difference between bone marrow cells and peripheral blood cell. A number of injected CD34+ cells and serum levels of angiogenic cytokines after treatment did not significantly differ between bone marrow cells and peripheral blood cell. CONCLUSIONS: Our study showed a superior benefit of bone marrow cells and peripheral blood cell treatments of critical limb ischaemia in patients with diabetic foot disease when compared with conservative therapy. There was no difference between both cell therapy groups, and no patient demonstrated signs of systemic vasculogenesis.


Assuntos
Transplante de Medula Óssea , Pé Diabético/terapia , Isquemia/prevenção & controle , Leucócitos Mononucleares/transplante , Salvamento de Membro , Transplante de Células-Tronco de Sangue Periférico , Idoso , Antígenos CD34/metabolismo , Monitorização Transcutânea dos Gases Sanguíneos , Transplante de Medula Óssea/efeitos adversos , Transplante de Medula Óssea/imunologia , Citocinas/sangue , Pé Diabético/imunologia , Pé Diabético/fisiopatologia , Pé Diabético/cirurgia , Feminino , Seguimentos , Humanos , Isquemia/etiologia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Extremidade Inferior , Masculino , Pessoa de Meia-Idade , Transplante de Células-Tronco de Sangue Periférico/efeitos adversos , Transplante Autólogo
9.
Vnitr Lek ; 57(5): 451-5, 2011 May.
Artigo em Tcheco | MEDLINE | ID: mdl-21695925

RESUMO

AIM: The aim of our study was to assess safety and effectiveness of therapy of critical limb ischaemia by autologous stem cells and evaluation of potential adverse events. METHODS: Fourteen patients were included into the study (11 men, 3 women, mean age 61.9 +/- 9.6 years, mean diabetes duration 23.5 +/- 11.1 years, mean glycated hemoglobin 6 +/- 1%). Eight patients were treated by bone marrow stromal cells, 6 patients by peripheral blood progenitor cells after stimulation by filgrastim. The suspension of stem cells was then applied into the muscles of ischemic limbs. We evaluated transcutaneous oxygen tension (TcPO2), subjective pain sensation assessed by Visual Analog Scale (VAS) and wound healing. RESULTS: TcPO2 significantly increased in all patients from 10 +/- 8.7 mm Hg before the treatment to 39.4 +/- 9.5 mm Hg after 6 months (p = 0.0005) after stem cell therapy. We also observed significant area defect reduction and pain decrease during the follow-up period. Median of area defect was reduced from 4.3 (0.7 - 31.7) before the treatment to 0.06 (0 - 0.5) cm2 after 6 months from the treatment (p = 0.0078). Decrease in rest pain was observed in all patients, mean VAS decreased from 5.3 +/- 1.8 to 1.1 +/- 1.3 after 6 months (p = 0.002). CONCLUSION: Our study suggests that stem cell therapy of diabetic foot disease is an effective therapeutic option with no adverse events for patients with severe peripheral arterial disease. This treatment leads to increase of transcutaneous oxygen tension, improves wound healing and decreases the rest pain.


Assuntos
Complicações do Diabetes , Pé Diabético/terapia , Isquemia/terapia , Perna (Membro)/irrigação sanguínea , Transplante de Células-Tronco , Idoso , Monitorização Transcutânea dos Gases Sanguíneos , Pé Diabético/complicações , Feminino , Humanos , Isquemia/complicações , Masculino , Pessoa de Meia-Idade , Medição da Dor , Transplante de Células-Tronco/métodos
10.
Anticancer Res ; 12(5): 1663-5, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1359832

RESUMO

The effect of Toremifene on cell growth in vitro was tested on the R3230AC rat mammary adenocarcinoma as model. Toremifene differed from Tamoxifen in that it did not induce resistance; some cross-resistance was observed in Tamoxifen tolerant tumour cell lines. Toremifene does not influence P-glycoprotein expression in this model and at the levels studied.


Assuntos
Adenocarcinoma/patologia , Divisão Celular/efeitos dos fármacos , Neoplasias Mamárias Experimentais/patologia , Toremifeno/farmacologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP , Animais , Anticorpos Monoclonais , Resistência a Medicamentos , Glicoproteínas de Membrana/análise , Ratos , Tamoxifeno/farmacologia , Células Tumorais Cultivadas
11.
Biochemistry ; 25(6): 1208-16, 1986 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-3964672

RESUMO

ts 2 BalB/C-3T3 mouse fibroblasts are cdc mutants, which arrest late in G1, at or near the G1/S traverse, upon full expression of the heat-sensitive lesion. The kinetics of temperature inhibition of DNA synthesis in logarithmically growing cultures reveal three stages of heat inactivation. During the first generation time equivalent, normal semiconservative, semidiscontinuous replication proceeds but is reduced as cells exit and do not reenter S phase. During a second such period, a minimal rate of normal DNA synthesis is maintained. Thereafter, as the cells move into a third aborted cell division cycle, the rate of DNA synthesis increases. However, all semiconservative synthesis is then replaced by DNA repair replication. Temperature inactivation of the ts 2 protein results in shutdown of nuclear DNA synthesis. In contrast, normal replication of mitochondrial DNA proceeds at control rate throughout the first stage of temperature inactivation. Synthesis of this organellar genome is quantitatively reduced as the cells move into the second phase of heat inhibition. Titration of chromatin-bound DNA with ethidium bromide revealed that wild-type cells exhibit a changing DNA topology as the temperature is raised. Temperature-inactivated ts 2 cells behave as though their DNA has been topologically frozen in the configuration of control cells at or near entry into S phase.


Assuntos
Replicação do DNA , Interfase , Animais , Autorradiografia , Radioisótopos de Carbono , Células Cultivadas , Cinética , Camundongos , Camundongos Endogâmicos BALB C , Temperatura , Timidina/metabolismo
12.
Exp Cell Res ; 161(2): 393-405, 1985 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-4065226

RESUMO

The ts 2 derivative of BALB/c-3T3 mouse fibroblasts is a cell division cycle (cdc) mutant. Upon expression of the heat-sensitive defect, ts 2 cells arrest late in G1 at, or very near the G1/S traverse. This conclusion derives from three kinds of experiment. In the first the cells were brought to different stages of the cell cycle by physiological manipulation, or with specific anti-metabolites. They were then released from the resulting blocks, and their subsequent cell-cycle progression, at the permissive- and non-permissive temperature (npt), was followed. The second experiment was an execution point analysis. In the third, premature chromosome condensation was performed between metaphase HeLa cells and temperature-blocked ts 2 cells. The resulting prematurely-condensed chromosomes were largely of the morphotype of very late G1 cells. The ts 2 cells are prevented from expressing their defect by temporary incubation at 38.5 degrees C in the G0, non-cycling state and by prior arrest in early S phase, imposed by hydroxyurea treatment. Such prevention is not allowed ts 2 cells incubated at the npt in the absence of isoleucine, a procedure which brings cells to mid-G1 arrest.


Assuntos
Ciclo Celular , Fibroblastos/metabolismo , Animais , Ciclo Celular/efeitos dos fármacos , Divisão Celular , Linhagem Celular , Cromossomos/ultraestrutura , Replicação do DNA , Fibroblastos/efeitos dos fármacos , Temperatura Alta , Hidroxiureia/farmacologia , Isoleucina/metabolismo , Camundongos , Camundongos Endogâmicos BALB C/genética , Biossíntese de Proteínas , Proteínas/fisiologia
13.
Intervirology ; 24(3): 174-80, 1985.
Artigo em Inglês | MEDLINE | ID: mdl-2999031

RESUMO

Mouse adenovirus multiplies, apparently without impediment, in temperature-inactivated ts A1S9, tsC1 and ts2 mouse fibroblasts. Thus, the DNA of mouse adenovirus can replicate in the absence of functional DNA topoisomerase II, a DNA-chain-elongation factor, and a protein required for traverse of the G1/S interface, respectively, encoded in the ts A1S9, tsC1 and ts2 genetic loci. These results are compared with those obtained with polyoma virus.


Assuntos
Adenoviridae/crescimento & desenvolvimento , DNA/biossíntese , Polyomavirus/crescimento & desenvolvimento , Replicação Viral , Adenoviridae/metabolismo , Animais , Células Cultivadas , Replicação do DNA , DNA Viral/biossíntese , Camundongos , Mutação , Polyomavirus/metabolismo , Temperatura
14.
Can J Biochem ; 58(12): 1359-69, 1980 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-6454476

RESUMO

Mouse L-cells treated with cytosine arabinoside, hydroxyurea, fluorodeoxyuridine, methotrexate, or mitomycin C rapidly cease DNA synthesis and stop dividing. Such inhibition of DNA replication is followed by interruption of formation of lysine- and arginine-containing proteins, including chromatin-bound histones, and by a major reorganization of the heterochromatin of the central nucleoplasm, manifest as disaggregation of large clumps of this condensed chromatin. Morphometric analysis revealed both cell and nuclear enlargement in cells treated with such antimetabolites of DNA replication. These observations are in contrast to those made with WT-4 cells starved of isoleucine or treated with cycloheximide. Isoleucine depletion was associated with inhibition of DNA synthesis and continued increase of cell and nuclear volume, but not with massive disaggregation of heterochromatin. Cycloheximide produced inhibition of DNA synthesis and protoplasmic growth, and also prevented structural reorganization of chromatin. A model is presented which suggests that initiation of chromatin replication is associated with a process, dependent upon de novo protein synthesis, which results in chromatin disaggregation. This can be revealed by inhibition of the correct replication of chromatin DNA and chromatin protein.


Assuntos
Cromatina/metabolismo , Replicação do DNA , Células L/metabolismo , Animais , Cicloeximida/farmacologia , Citarabina/farmacologia , Replicação do DNA/efeitos dos fármacos , Floxuridina/farmacologia , Hidroxiureia/farmacologia , Isoleucina/deficiência , Células L/efeitos dos fármacos , Metotrexato/farmacologia , Camundongos , Mitomicina , Mitomicinas/farmacologia , Biossíntese de Proteínas , Relação Estrutura-Atividade
15.
J Cell Biol ; 77(1): 246-63, 1978 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-659512

RESUMO

Mutant lines of mouse L cells, TS A1S9, and TS C1, show temperature-sensitive (TS) DNA synthesis and cell division when shifted from 34 degrees to 38.5 degrees C. With TS A1S9 the decline in DNA synthesis begins after 6-8 h at 38.5 degrees C and is most marked at about 24 h. Most cells in S, G2, or M at temperature upshift complete one mitosis and accumulate in the subsequent interphase at G1 or early S as a result of expression of a primary defect, failure of elongation of newly made small DNA fragments. Heat inactivation of TS C1 cells is more rapid; they fail to complete the interphase in progress at temperature upshift and accumulate at late S or G2. Inhibition of both cell types is reversible on return to 34 degrees C. Cell and nuclear growth continues during inhibition of replication. Expression of both TS mutations leads to a marked change in gross organization of chromatin as revealed by electron microscopy. Nuclei of wild-type cells at 34 degrees and 38.5 degrees C and mutant cells at 34 degrees C show a range of aggregation of condensed chromatin from small dispersed bodies to large discrete clumps, with the majority in an intermediate state. In TS cells at 38.5 degrees C, condensed chromatin bodies in the central nuclear region become disaggregated into small clumps dispersed through the nucleus. Morphometric estimation of volume of condensed chromatin indicates that this process is not due to complete decondensation of chromatin fibrils, but rather involves dispersal of large condensed chromatin bodies into finer aggregates and loosening of fibrils within the aggregates. The dispersed condition is reversed in nuclei which resume DNA synthesis when TS cells are downshifted from 38.5 degrees to 34 degrees C. The morphological observations are consistent with the hypothesis that condensed chromatin normally undergoes an ordered cycle of transient, localized disaggregation and reaggregation associated with replication. In temperature-inactivated mutants, normal progressive disaggregation presumably occurs, but subsequent lack of chromatin replication prevents reaggregation.


Assuntos
Ciclo Celular , Cromatina/ultraestrutura , Interfase , Contagem de Células , Divisão Celular , Núcleo Celular/ultraestrutura , DNA/biossíntese , Células L , Mutação , Temperatura
16.
J Biol Chem ; 253(3): 922-6, 1978 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-621211

RESUMO

When ts A1S9 mouse L-cells are incubated at the nonpermissive temperature (38.5 degrees) DNA synthesis proceeds at the normal rate for 6 to 8 h; it then declines to attain 1 to 5% of this rate after 24 h. General protein synthesis from precursor leucine is relatively unaffected by the high temperature. In contrast, protein formation from lysine (and arginine) remains unchanged for 12 to 15 h after temperature upshift. It then drops and plateaus at about 25% of the initial rate after 32 h. The chromatin protein and DNA are fully conserved in ts A1S9 cells incubated at 38.5 degrees for at least 24 h after full expression of the ts defect. Temperature inactivation of the ts A1S9 gene product results in inhibition of de novo formation of chromatin. This is evidenced by coordinate suppression of incorporation of dThd and of lysine and arginine into chromatin-bound DNA and histone, respectively.


Assuntos
Cromatina/biossíntese , Replicação do DNA , Células L/metabolismo , Histonas/biossíntese , Biossíntese de Proteínas , Temperatura
17.
Can J Biochem ; 55(5): 543-7, 1977 May.
Artigo em Inglês | MEDLINE | ID: mdl-560242

RESUMO

Temperature-sensitive (ts) A 1S9 mouse L cells continue to synthesize double-stranded covalently closed mitochondrial (mt) DNA at a temperature (38.5 degrees C) which is nonpermissive for chromosomal DNA replication. The amount of mt DNA made appears to be quantitatively linked to nuclear DNA synthesis. Nuclear DNA replication proceeds normally for 6-8 h after the cells are shifted to 38.5 degrees C, and then declines to reach a minimum at 20-24 h. The level of mt DNA synthesis remains high during this period and decreases once the ts lesion has been established.


Assuntos
DNA Mitocondrial/biossíntese , Células L/metabolismo , Animais , Núcleo Celular/metabolismo , Replicação do DNA , Camundongos , Temperatura , Timidina/metabolismo
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