ABSTRACT
AIMS: To assess circadian blood pressure variability in people with impaired glucose tolerance and a healthy control population. METHODS: Seventy-five people with impaired glucose tolerance and 40 healthy volunteers (frequency matched on 10-year age bands and sex) underwent a detailed neurological assessment. Autonomic neuropathy was detected by the five standard cardiovascular autonomic tests and heart rate variability was characterized by the triangle index. Diurnal indices were assessed by 24-h ambulatory blood pressure monitoring. Systolic and diastolic diurnal indices were defined as: (mean daytime blood pressure - mean night-time blood pressure) × 100/mean daytime blood pressure. RESULTS: Mean 24-h systolic and diastolic blood pressure was significantly higher in the group with impaired glucose tolerance compared with the control group [126 ± 12 (mean ± SD) vs. 117 ± 10, 75 ± 7 vs. 71 ± 6 mmHg, both P < 0.05). Systolic and diastolic diurnal indices and heart rate variability triangular index were significantly lower in people with impaired glucose tolerance compared with control subjects (9.1 ± 7.8 vs. 13.2 ± 5.4, 14.5 ± 9.7 vs. 18.4 ± 7.1 mmHg, 28.0 ± 8.4 vs. 39.5 ± 9.3, all P < 0.05). Differences in mean diastolic blood pressure, heart rate variability triangular index and the frequency of non-dippers between those with impaired glucose tolerance and control subjects seemed to be independent of BMI and the presence of cardiovascular autonomic neuropathy, as simultaneous adjustment for BMI and cardiovascular autonomic neuropathy had no major effect on the results. CONCLUSION: Our data suggest that people with impaired glucose tolerance have increased diastolic blood pressure and abnormal circadian blood pressure regulation, independent of obesity and the presence of cardiovascular autonomic neuropathy.
Subject(s)
Autonomic Nervous System Diseases/physiopathology , Blood Pressure/physiology , Circadian Rhythm/physiology , Glucose Intolerance/physiopathology , Autonomic Nervous System Diseases/etiology , Blood Glucose/metabolism , Body Mass Index , Case-Control Studies , Female , Glucose Intolerance/complications , Glycated Hemoglobin/metabolism , Heart Rate/physiology , Humans , Male , Middle AgedABSTRACT
BACKGROUND: Adalimumab is a fully human monoclonal antibody targeting tumour necrosis factor with proven efficacy in the treatment of Crohn's disease (CD). AIM: To investigate the predictors of medium-term clinical efficacy and mucosal healing during adalimumab therapy, in patients with CD, in specialised centres approved for biological therapy in Hungary. METHODS: Data capture of the 201 CD patients was standardised and prospective (male/female: 112/89, median age: 33.0 years, duration: 8 years). Previous infliximab therapy had been administered in 48% of patients, concomitant steroids in 41%, azathioprine in 69% and combined therapy in 27% of patients. RESULTS: Overall clinical response and remission rates at 24 weeks were 78% and 52%, respectively; at 52 weeks were 69% and 44%, respectively. Endoscopic improvement and healing were achieved in 43% and 24% of patients. In a logistic regression model, clinical efficacy and CRP at week 12, need for combined immunosuppression at induction, shorter disease duration and smoking were identified as independent predictors for 12-month clinical outcome, whereas CRP at week 12, clinical remission at week 24, inflammatory parameters and nonsmoking were associated to endoscopic improvement/healing. Intensification to weekly dosing was needed in 16% of patients. Parallel azathioprine therapy and clinical remission at week 12 were inversely associated with dose escalation. CONCLUSIONS: Clinical efficacy and normalised CRP at week 12 (early deep clinical remission) are associated with medium-term clinical efficacy and mucosal healing during adalimumab therapy, whereas need for combined immunosuppression at induction and smoking status are predictors for non-response. Parallel azathioprine therapy may decrease the probability for dose escalation.
Subject(s)
Anti-Inflammatory Agents/administration & dosage , Antibodies, Monoclonal, Humanized/administration & dosage , C-Reactive Protein/metabolism , Crohn Disease/drug therapy , Intestinal Mucosa/drug effects , Adalimumab , Adult , Crohn Disease/blood , Dose-Response Relationship, Drug , Female , Follow-Up Studies , Humans , Intestinal Mucosa/immunology , Logistic Models , Male , Predictive Value of Tests , Prospective Studies , Remission Induction , Time Factors , Treatment Outcome , Young AdultABSTRACT
BACKGROUND: The incidence of fractures is substantially increased in patients with chronic kidney disease (CKD) compared to the general population. The factors associated with increased bone fracture in this population are not well understood. Vitamin D deficiency has been associated with decreased bone mass and higher incidence of fractures in the general population. In this study, we aimed to assess the association between fracture and vitamin D status and other factors potentially associated with fracture in patients on maintenance hemodialysis. METHODS: One hundred and forty-four patients were assessed and interviewed about previous low-trauma fractures. Evidence of fracture was obtained from medical records and also through patient interviews. Routine laboratory results were collected from medical records. Serum intact PTH (iPTH) and 25(OH) vitamin D(3) were measured. All patients underwent bone densitometry of the lumbar spine, femoral neck and distal radius. Bone quality was also assessed with quantitative bone ultrasound (QUS). Descriptive statistics, logistic regression models were used to analyze factors associated with fractures. RESULTS: One hundred and thirty patients were included in the final analysis. Patients with fractures (n = 21) had lower 25(OH) vitamin D(3) levels (15.8 nmol/l (interquartile range, IQR: 27) vs. 30.0 nmol/l (IQR: 28.5), P = 0.029), were more likely females, had longer duration of end-stage kidney disease, and lower bone mineral density (BMD) at the distal radius. QUS parameters were not associated with fractures. Multivariate analyses revealed that serum 25(OH) vitamin D(3) concentration, BMD at the radius, iPTH less than 100 pg/ml and history of fractures were independent predictors of new bone fracture after the initiation of dialysis therapy. CONCLUSION: Increased bone fragility in dialysis patients is associated with vitamin D deficiency and relative hypoparathyroidism in addition to reduced BMD at the radius. Further studies are needed to determine whether patients with vitamin D deficiency benefit from vitamin D supplementation to reduce fracture risk.
Subject(s)
Fractures, Bone/etiology , Renal Dialysis , Vitamin D Deficiency/complications , Cohort Studies , Female , Fractures, Bone/epidemiology , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
BACKGROUND: The relationship between parathyroid function, an important determinant of bone turnover, and bone mineral density (BMD) in patients with chronic kidney disease is not fully understood. We wanted to analyze the association between BMD and parathyroid function in hemodialysis patients in details. METHODS: In a cross-sectional design, data from 270 patients (age 55 ± 15 years, 60% men, all Caucasian) on maintenance hemodialysis were analyzed. All patients underwent dual energy X-ray absorptiometry of the lumbar spine (LS), femoral neck (FN) and distal radius (DR). In addition to routine laboratory tests, blood samples were collected for iPTH, serum markers of bone metabolism (alkaline phosphatase, type I collagen crosslinked-C-telopeptide) and 25OH vitamin D. RESULTS: Based on Z-scores, bone mineral density was moderately reduced only at the femoral neck in the total cohort. The average Z-score of the "low PTH" group (iPTH < 100 pg/ml) was not different from the Z-score of patients with iPTH in the "target range" (100-300 pg/ml) at any measurement site. While iPTH was negatively correlated with BMD at all measurement sites in patients with iPTH > 100 pg/ml (rho = -0.255, -0.278 and -0.251 for LS, FN and DR, respectively, P < 0.001 for all), BMD was independent of iPTH in patients with iPTH < 100 pg/ml. Furthermore, iPTH was not associated with serum markers of bone metabolism, but these markers were negatively correlated with BMD in the "low PTH" group. CONCLUSIONS: Low PTH levels are not associated with low BMD in patients with end-stage kidney disease. Furthermore, bone metabolism seems to be independent of iPTH in patients with relative hypoparathyroidism likely reflecting skeletal resistance to PTH.
Subject(s)
Bone Density , Bone Diseases, Metabolic/blood , Kidney Failure, Chronic/therapy , Parathyroid Hormone/blood , Absorptiometry, Photon , Bone Diseases, Metabolic/epidemiology , Bone Diseases, Metabolic/etiology , Cross-Sectional Studies , Female , Humans , Hungary/epidemiology , Incidence , Kidney Failure, Chronic/blood , Kidney Failure, Chronic/complications , Male , Renal Dialysis , Risk FactorsABSTRACT
The passage of highly specialized germ cells to future generations is essential for the maintenance of species. To date, conventional genetic screens identified relatively few genes that are involved in germ cell development. We aimed to identify germ line specific genes on the X chromosome of Drosophila melanogaster by the application of a new method: the dual-tagging gene-trap system (GT). A modified version of the gene-trap element was used in our experiments and the resulting insertional mutants were screened for grandchild-less phenotype with the help of the attached-X system and a sensitized genetic background developed in our laboratory. Among the 800 insertions mapped to the X chromosome 33 new mutations were identified that exhibited grandchild-less phenotype, 6 gave visible phenotype and 12 were conditional lethal. The cloning of a selected group of the 33 lines showing grandchild-less phenotype confirmed that we have identified new candidates for genes involved in germ cell development. One of them named pebbled (peb) is discussed in details in this paper. Finally, we also describe a novel automatic selection system developed in our laboratory which enables the extension of the GT mutagenesis to the autosomes.
Subject(s)
Automation , Drosophila melanogaster/embryology , Genetic Markers , Germ Cells/cytology , Animals , Base Sequence , DNA Primers , Mutagenesis , Polymerase Chain Reaction , X ChromosomeABSTRACT
UNLABELLED: Previous studies indicated that elevated tumour necrosis factor-alpha (TNF-alpha) levels may play a role in the development of necrotizing enterocolitis (NEC). The A(-308) and A(-238) variants of the promoter region of the TNF-alpha gene are reportedly associated with altered TNF-alpha production. The aim of our study was to determine the impact of these gene polymorphisms on the development and course of NEC in very-low-birthweight (VLBW) infants. Dried blood samples from 46 VLBW neonates with NEC were analysed using the method of restriction fragment length polymorphism. Samples from 90 VLBW neonates without NEC were used as controls. The prevalence of alleles with guanine-adenine transition in the -308 and -238 positions was the same in NEC and control subjects (12% vs 10% and 3% vs 4%, respectively). CONCLUSION: The investigated genetic variants of the TNF-alpha gene promoter region have no influence on the risk and course of NEC in VLBW infants.
Subject(s)
Adenine , Alleles , Enterocolitis, Necrotizing/genetics , Infant, Very Low Birth Weight , Promoter Regions, Genetic , Tumor Necrosis Factor-alpha/genetics , Humans , Infant, NewbornABSTRACT
AIM: Data are inconsistent whether hyperinsulinemia might be associated with adrenal hyperandrogenism in young adults born with low birth weight (LBW). METHOD: We investigated the insulin and adrenal steroid production of 70 young LBW adults [33 women (birth weight: 1,795 +/- 435 g) and 37 men (birth weight: 1,832 +/- 337 g)]. Their results were compared to those of 30 controls (14 men, 16 women), born with normal weight. RESULTS: In LBW women, we measured higher basal DHEA (33.5 +/- 13.1 vs. 23.6 +/- 8.7 nmol/l, p < 0.05), DHEAS (8.0 +/- 2.3 vs. 6.3 +/- 2.1 micromol/l, p < 0.05), androstenedione (8.3 +/- 2.8 vs. 6.0 +/- 2.2 nmol/l, p < 0.05) and cortisol (0.25 +/- 0.07 vs. 0.20 +/- 0.07 micromol/l, p < 0.05) levels and higher insulin response during oral glucose tolerance test (log.AUCins: 2.62 +/- 0.06 vs. 2.57 +/- 0.03, p < 0.05). DHEA levels correlated with fasting insulin levels (r = 0.45, p < 0.01) and insulin response (r = 0.33, p < 0.05). In LBW men, higher cortisol (0.27 +/- 0.06 vs. 0.22 +/- 0.06 micromol/l, p < 0.01) and SHBG (18.4 +/- 10.4 vs. 12.7 +/- 5.9 nmol/l, p < 0.05) levels were found. CONCLUSIONS: Our results suggest that modest hypercortisolism is present in young LBW adults. While the endocrine sequel of hypercortisolism raised insulin response and hyperandrogenism is detectable in apparently healthy young LBW women, it is absent in young LBW men. This suggests that gender-dependent mechanisms might play a role in the development of insulin resistance in LBW adults.
Subject(s)
Adrenal Glands/metabolism , Aging/metabolism , Carbohydrate Metabolism , Infant, Low Birth Weight/physiology , 17-alpha-Hydroxyprogesterone/metabolism , Adult , Androstenedione/metabolism , Dehydroepiandrosterone/metabolism , Dehydroepiandrosterone Sulfate/metabolism , Female , Humans , Hydrocortisone/blood , Hydrocortisone/metabolism , Hyperandrogenism/metabolism , Hyperandrogenism/physiopathology , Infant, Newborn , Insulin/metabolism , Male , Sex Hormone-Binding Globulin/metabolism , Testosterone/metabolismABSTRACT
OBJECTIVES: Osteoporosis is a complication of coeliac disease. A gluten-free diet improves but does not normalize bone mineral density in adult patients. Only limited data are available regarding the influence of the disease and diet on bone mineralization in children. The aim of this study was to evaluate the radial bone mineral content and density in children and adolescents who are asymptomatic on a gluten-free diet. SUBJECTS AND METHODS: The bone mineral content (BMC) and density (BMD) values of the non-dominant radius midshaft in 91 children (53 girls, 38 boys, mean age 11.7 years, mean duration of disease 8.7 years) were determined by single-photon absorptiometry. At the diagnosis and at least three years after commencement of a gluten-free diet, serum calcium, phosphorus, albumin concentrations and alkaline phosphatase activities were measured in all patients, and intact parathormone concentrations in 16 patients. RESULTS: The mean BMC Z-score value in the female adolescent group only was significantly lower than normal (mean Z-score -1.04, P < 0.01). In contrast, the mean BMD Z-score was significantly higher compared to a healthy population both in girls (mean Z-score +1.36, P < 0.001) and in boys (mean Z-score +0.53, P < 0.02), as well as in the total patient group (mean Z-score +1.01, P < 0.001). The radial diameter was significantly smaller than normal in both pre-pubertal and adolescent groups. Serum laboratory parameters of asymptomatic patients were in the normal range. The parathormone mean value was significantly lower after at least three years of gluten-free diet than at diagnosis (mean +/- SD 3.77 +/- 1.07 versus 7.89 +/- 2.54 pmol/l, P < 0.01), but significantly higher compared to controls (2.89 +/- 0.90 pmol/l, P < 0.05). CONCLUSIONS: These data indicate that treated, asymptomatic coeliac children and adolescents have normal or even higher radius mineral density values than controls, but the bone size remains reduced. Although there is no direct evidence of calcium malabsorption in this cohort of coeliac patients, the slightly higher parathormone levels, together with some other factors, particularly delayed puberty, may result in reduced bone size.
Subject(s)
Bone Density , Celiac Disease/physiopathology , Absorptiometry, Photon , Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Radius/physiologySubject(s)
Cardiovascular Diseases/etiology , Infant, Premature , Adult , Birth Weight , Dehydroepiandrosterone/blood , Female , Fetal Growth Retardation/complications , Gestational Age , Heart Rate/physiology , Humans , Hydrocortisone/blood , Hypertension/blood , Hypertension/etiology , Infant, Low Birth Weight , Infant, Newborn , Infant, Small for Gestational Age , Male , Risk Factors , Sex FactorsABSTRACT
It is known that the prevalence of cardiovascular diseases, hypertension, noninsulin dependent diabetes mellitus and dyslipidemia in the late adulthood are in connection with intrauterine retardation, characterized by low birth weight. One possible explanation of this phenomenon is the abnormality of hypothalamus-hypophysis-adrenal cortex axis due to the accelerated growth. The authors investigated the steroid levels of young adults; whom birth weight were under 2500 g, and examined the relationship between hormone levels and some parameters of glucose metabolism and cardiovascular system. 75 subjects (43 female and 32 male patients, mean age: 19.6 and 19.8 years, respectively; range 18-22 ys) with low birth weight and without any sign of chronic disease, and 30 healthy, age-matched controls with normal birth weight were investigated. The basal serum cortisol, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS), androstenedione (AD), 17-hydroxyprogesterone (17OHP), estradiol (OE), sex-hormone binding globulin (SHBG), FSH, LH and insulin levels were determined. Moreover, oral glucose tolerance test with 75 g glucose (OGTT), impedance cardiography as well as ambulatory blood pressure monitoring were done by all subjects. In both sexes in subjects with low birth weight the mean serum cortisol level was significantly higher, than in the normal controls. In female patients the serum DHEA, DHEAS, AD, and 17OHP levels were significantly higher than in the controls. Moreover, among these females a relationship was found between the elevations of adrenal and gonadal steroids and hyperinsulinemia, characterized by increased insulin response during OGTT. In male subjects a significant correlation was found between serum cortisol levels and systolic blood pressure and heart rate. In females there was a positive relationship between serum DHEA and heart rate. Summarized, the basic abnormality in patients with low birth weight seems to be a relative hypercortisolism, and in females because of hyperinsulinemia exists a mild hyperandrogenism as well. The hypercortisolism may cause cardiovascular abnormalities in males directly, while in females indirectly through the hyperinsulinemia and hyperandrogenism. These subtle abnormalities can be detected when no clinical signs present themselves, in young adulthood, giving the opportunity of taking preventive actions.
Subject(s)
Blood Pressure , Dietary Carbohydrates/metabolism , Gonadal Steroid Hormones/blood , Heart Rate , Hydrocortisone/blood , Infant, Low Birth Weight , 17-alpha-Hydroxyprogesterone/blood , Adult , Androstenedione/blood , Blood Glucose/metabolism , Case-Control Studies , Dehydroepiandrosterone/blood , Estradiol/blood , Female , Follicle Stimulating Hormone/blood , Glucose Tolerance Test , Humans , Infant, Newborn , Insulin/blood , Luteinizing Hormone/blood , Male , Regression Analysis , Sex Factors , Sex Hormone-Binding Globulin/metabolism , Testosterone/bloodABSTRACT
As the result of accelerated growth, the final height of infants born with low birth weight (LBW) is near to the normal. Limited data are available about the bone density and bone turnover just after completion of skeletal development. We have investigated the bone turnover and bone density in 49 apparently healthy young LBW men (age 19-21 years; 21 born small for gestational age (SGA) and 28 appropriate for gestational age (AGA)) and in 16 age-matched controls. Bone mineral density of lumbar spine, femoral neck, and radius midshaft, the markers of calcium homeostasis, biochemical parameters of bone turnover as serum osteocalcin (OC), and urinary pyridinoline (PYD) and deoxypyridinoline (DPD) levels were measured. Bone mineral densities of LBW subjects were not altered. Serum calcium (SGA: 2.44+/-0.15; AGA:2.41+/-0.17, control: 2.25+/-0.09 mmol/liter, P < 0.05), OC (SGA:23.4+/-9.9; AGA:20.8+/-7.6; control:13.3+/-4.6 ng/ml, P < 0.01), total alkaline phosphatase (AP) (SGA:201+/-61; AGA:193+/-81, control: 117+/-34 IU/liter, P < 0.01), and urinary DPD/creat (ln.values: SGA:3.10+/-0.48; AGA:3.17+/-0.46; control:2.58+/-0.57 nmol/mmol, P < 0.05) were higher, whereas fractional excretion of calcium (SGA:0.94+/-0.470; AGA: 1.03+/-0.51, control:1.31+/-0.75%, P < 0.05) was lower in both SGA and AGA groups. PTH and 25OHD were not different. Significant correlation was obtained between seCa, OC, AP, DPD and birth weight of the subjects, but feCa correlated inversely to the birth weight. It was concluded that the bone turnover of LBW men is accelerated, but well balanced in young adulthood. Further investigation is needed to describe the possible link between accelerated bone turnover and hormonal homeostasis of LBW subjects.
Subject(s)
Amino Acids/urine , Infant, Low Birth Weight/metabolism , Osteocalcin/blood , Absorptiometry, Photon , Adult , Alkaline Phosphatase/blood , Biomarkers/blood , Biomarkers/urine , Birth Weight/physiology , Bone Density/physiology , Bone Remodeling/physiology , Calcium/blood , Calcium/urine , Femur Neck/diagnostic imaging , Femur Neck/metabolism , Humans , Infant, Low Birth Weight/growth & development , Infant, Newborn , Lumbar Vertebrae/diagnostic imaging , Lumbar Vertebrae/metabolism , Male , Radius/diagnostic imaging , Radius/metabolismABSTRACT
In many countries osteoporosis is the most common metabolic bone diseases. A great deal is known about the pathophysiology and the treatment of the disease. There is a lot of treatment possibilities and many new treatments are being tested. Therapeutic agents for osteoporosis are correspondingly classified as substances primarily inhibiting bone turnover (most of them are inhibitors of bone resorption as well) and agents that appear capable of restoring bone mass previously lost (stimulators of bone formation). From a didactic point of view the distinction of these to groups is generally accepted, but pharmacologically there is a considerable overlap between two. In this review the authors evaluate non-hormonal drugs, which are being used widely in the treatment of osteoporosis. The key points of the evaluation are the mechanism of action, the effects on bone mass, bone strength and fracture.
Subject(s)
Calcitonin/administration & dosage , Calcium/administration & dosage , Menopause/physiology , Osteoporosis/prevention & control , Postmenopause/physiology , Adult , Anabolic Agents/administration & dosage , Anabolic Agents/pharmacology , Benzothiadiazines , Calcitonin/pharmacology , Calcium/pharmacology , Diuretics , Female , Humans , Middle Aged , Osteoporosis/drug therapy , Sodium Chloride Symporter Inhibitors/administration & dosage , Sodium Chloride Symporter Inhibitors/pharmacologyABSTRACT
Clinical resistance to chemotherapeutic drugs is an important problem in the treatment of cancer; the circumvention of resistance has become one of the basic goals of cancer therapy. The most frequent form of primary liver cancer is hepatocellular carcinoma, which is essentially refractory to chemotherapy. We earlier showed that TT-232, a new somatostatin analogue developed in our laboratory, exerted a strong antiproliferative effect both in vitro and in vivo, but no growth hormone release inhibitory or antisecretory activity. Here we report that TT-232 has a pronounced antiproliferative effect on differentiated and dedifferentiated, drug-sensitive and multidrug-resistant hepatocellular carcinoma cell lines. TT-232 induces apoptosis at comparable levels in all these hepatoma variants demonstrating that the multidrug resistance of hepatomas does not correlate with a reduced susceptibility to apoptosis induction. These results clearly reveal that the machinery involved in apoptosis is functional in both drug-sensitive and resistant hepatoma variants and can be activated by the somatostatin analogue TT-232.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Carcinoma, Hepatocellular/drug therapy , Cell Differentiation/drug effects , Drug Resistance, Multiple , Liver Neoplasms/drug therapy , Peptides, Cyclic/pharmacology , Carcinoma, Hepatocellular/pathology , Cell Division/drug effects , Humans , Liver Neoplasms/pathology , Somatostatin/analogs & derivatives , Tumor Cells, Cultured/drug effectsABSTRACT
In this study 66 male patients with erectile dysfunction were investigated. The authors measured the testosterone levels in serum and in saliva, which latter represent with good accuracy the serum levels of free testosterone. The mean serum total testosterone level was 17.6 nmol/L (confidence intervals: 15.5 and 20.2 nmol/L, normal range: 10-50 nmol/L). The mean salivary free testosterone level was 218.5 pmol/L (confidence intervals: 198.3 and 239.9 pmol/L, normal range: 200-1000 pmol/L). Low salivary (free) testosterone levels were found in 36.4% of patients, while only in 10.6% of patients had low serum testosterone levels (p = 0.01, by binomial test). Although there is a relationship between serum and salivary testosterone levels (r = 0.41, p < 0.001), the patients with low salivary (free) testosterone levels have in major part a normal serum total testosterone level. These data indicate that a considerable proportion of patients with erectile dysfunction have androgen deficiency. The serum total testosterone level is not a sensitive indicator to detection of hypogonadism. The androgen substitution therapy has a beneficial effect on erectile dysfunction in a significant part of patients. The measurement of free testosterone level in saliva may have an important role both in the diagnosis of diseases characterized by androgen deficiency and hyperandrogenic status.
Subject(s)
Androgens/deficiency , Erectile Dysfunction/blood , Hypogonadism/blood , Saliva/chemistry , Testosterone/blood , Adult , Aged , Androgens/administration & dosage , Humans , Male , Middle Aged , Testosterone/deficiencyABSTRACT
BACKGROUND: Hyperthermia is used in the treatment of some human malignancies. Thermotolerance may interfere with the efficacy of hyperthermic treatment, and thermotolerant cells may also display an enhanced resistance to some anticancer drugs. We have earlier isolated stable heat-resistant rat hepatoma variants and examined whether heat resistance influenced the drug sensitivity of the cells. MATERIALS AND METHODS: Heat-resistant variants were isolated by ten repeated cycles of heat exposure at 45 degrees C for 80 min. Highly multidrug-resistant variants were isolated by stepwise selection with colchicine. RESULTS: The heat-resistant variants became moderately multidrug resistant. This resistance was further increased by stepwise selection with colchicine (highly multidrug resistant variants). The levels of P-glycoprotein were elevated both in moderately and highly drug resistant variants. Decreased retention of antitumor drugs was observed in the multidrug resistant variants, verapamil increased doxorubicin retention significantly. Estradiol was almost without effect, while tamoxifen increased the drug uptake. Amplification of the MDR gene occurred in a part of the highly multidrug resistant variants. CONCLUSIONS: Acquired stable heat resistance of cancer cells can prevent the efficacy not only of hyperthermic treatment, but also the success of chemotherapy.