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H Dolezalova

Publications and source records attributed to H Dolezalova.

At least 19 recordsLinked to original sources
PubMed2000

Mechanisms of lysolipid phosphate effects on cellular survival and proliferation.

The specificity of cellular effects of lysolipid phosphate (LLP) growth factors is determined by binding to endothelial differentiation gene-encoded G protein-coupled receptors (EDG Rs), which transduce diverse proliferative and effector signals. The primary determinants of cellular responses to LLPs are the generative and biodegradative events, which establish steady-state concentrations of each LLP at cell surfaces, and the relative frequency of expression of each EDG R. There are major differences among types of cells in the net effective generation of the LLPs, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), and in their profile of expression of EDG Rs. The less well characterized secondary determinants of cellular specificity of LLPs are high-affinity binding proteins with carrier and cell-presentation functions, cell-selective regulators of expression of EDG Rs, and cellular factors that govern coupling of EDG Rs to G protein transductional pathways. The roles of components of the LLP-EDG R system in normal physiology and disease processes will be definitively elucidated only after development of animal models with biologically meaningful alterations in genes encoding EDG Rs and the discovery of potent and selective pharmacological probes.

Breast Neoplasms↗
PubMed2000

Prolonged cell cycle arrest in irradiated human diploid skin fibroblasts: the role of nutrient deprivation.

Ionizing radiation has been reported to cause an irreversible cell cycle arrest in normal human diploid fibroblasts. However, colony survival assays show that even at high doses of gamma radiation, human diploid fibroblasts do not irreversibly arrest, and that a dose-dependent fraction is capable of continued cycling. In this study, we resolve the apparent discrepancy between colony survival assays and the observed radiation-induced prolonged arrest. Using flow cytometry analysis, we have confirmed that human diploid fibroblasts do exhibit a prolonged cell cycle arrest in both G(1) and G(2)/M phases of the cell cycle. However, a single replacement of fresh growth medium stimulated a fraction of the arrested population of cells to transiently re-enter the cell cycle. Daily medium changes stimulated these irradiated human diploid fibroblasts to continue cycling until they were contact-inhibited. Thus the fraction of human diploid fibroblasts which survive radiation exposure and are capable of cycling appears to permanently arrest as a result of nutrient insufficiency. Western blot analysis demonstrated a radiation-induced elevation in TP53 (formerly known as p53) protein levels within 2 h postirradiation, followed by a decrease to levels comparable to those in unirradiated controls. The TP53 and CDKN1A (formerly known as p21) protein levels were indistinguishable after 24 h and remained elevated for a 6-day period of observation in both control and irradiated cultures. Our studies indicate that human diploid fibroblasts are capable of re-entering the cell cycle after exposure to ionizing radiation and that this re-entry is dependent on a constant supply of nutrients provided by fresh medium changes. The fraction of cells capable of resuming cell cycling is consistent with the surviving fraction of cells in colony assays.

Blotting, Western↗
PubMed1999

Distinctive expression and functions of the type 4 endothelial differentiation gene-encoded G protein-coupled receptor for lysophosphatidic acid in ovarian cancer.

Endothelial differentiation gene (edg)-encoded G protein-coupled receptors (Edg Rs)-1, -3, and -5 bind sphingosine 1-phosphate (S1P), and Edg-2 and -4 bind lysophosphatidic acid (LPA). Edg Rs transduce signals from LPA and S1P that stimulate ras- and rho-dependent cellular proliferation, enhance cellular survival, and suppress apoptosis. That high levels of LPA in plasma and ascitic fluid of patients with ovarian cancer correlate with widespread invasion suggested the importance of investigating expression and functions of Edg Rs in ovarian cancer cells (OCCs) as compared with nonmalignant ovarian surface epithelial cells (OSEs). Analyses of Edg Rs by semiquantitative reverse transcription-PCR, a radioactively quantified variant of PCR, and Western blots developed with monoclonal antibodies showed prominent expression of Edg-4 R in primary cultures and established lines of OCCs but none in OSEs. In contrast, levels of Edg-2, -3, and -5 were higher in OSEs than OCCs. LPA stimulated proliferation and signaled a serum response element-luciferase reporter of immediate-early gene activation in OCCs but not OSEs, whereas S1P evoked similar responses in both OSEs and OCCs. Pharmacological inhibitors of Edg R signaling suppressed OCC responses to LPA. A combination of monoclonal anti-Edg-4 R antibody and phorbol myristate acetate, which were inactive separately, evoked proliferative and serum response element-luciferase responses of OCCs but not OSEs. Thus the Edg-4 R may represent a distinctive marker of OCC that transduces growth-promoting signals from the high local concentrations of LPA characteristic of aggressive ovarian cancer.

Female↗
PubMed1999

Dual mechanisms for lysophospholipid induction of proliferation of human breast carcinoma cells.

Endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) Edg-1, Edg-3, and Edg-5 bind sphingosine 1-phosphate (S1P), and Edg-2 and Edg-4 Rs bind lysophosphatidic acid (LPA). LPA and S1P initiate ras- and rho-dependent signaling of cellular growth. Cultured lines of human breast cancer cells (BCCs) express Edg-3 > Edg-4 > Edg-5 > or = Edg-2, without detectable Edg-1, by both assessment of mRNA and Western blots with rabbit and monoclonal mouse anti-Edg R antibodies. BCC proliferation was stimulated significantly by 10(-9) M to 10(-6) M LPA and S1P. Luciferase constructs containing the serum response element (SRE) of growth-related gene promoters reported mean activation of BCCs by LPA and S1P of up to 85-fold. LPA and S1P stimulated BCC secretion of type II insulin-like growth factor (IGF-II) by 2-7-fold, to levels at which exogenous IGF-II stimulated increased proliferation and SRE activation of BCCs. All BCC responses to LPA and S1P were suppressed similarly by pertussis toxin, mitogen-activated protein kinase kinase inhibitors, and C3 exoenzyme inactivation of rho, suggesting mediation by Edg Rs. Monoclonal anti-IGF-II and anti-IGFR1 antibodies suppressed proliferation and SRE reports of BCCs to LPA and S1P by means of up to 65%. Edg Rs thus transduce LPA and S1P enhancement of BCC growth, both directly through SRE and indirectly by enhancing the contribution of IGF-II.

Animals↗
PubMed1998

Congenital megalourethra associated with urethral duplication and imperforate anus.

A newborn with a prenatal diagnosis of right hydroureteronephrosis and enlarged penis is presented. At birth, the baby had an imperforate anus (IA) with a megalourethra; radiologic and ultrasonographic studies showed a left polycystic kidney and right hydroureteronephrosis, right vesicoureteral reflux, and an incomplete urethral duplication with dilatation of the posterior urethra. The IA was corrected on the 1st day of life and a vesicostomy was performed at 1 month. At 1 year of age the valve obstructing the ventral posterior urethra was resected and the vesicostomy was closed. At 14 months the baby underwent a urethroplasty with a vertical preputial tubularized island flap and excision of the penile urethral duplication. Exact knowledge of the malformation was essential in planning the appropriate surgical treatment.

Anus, Imperforate↗
PubMed1995

Conformational changes in p53 analysed using new antibodies to the core DNA binding domain of the protein.

The p53 protein contains a protease resistant core section that binds to DNA in a sequence specific manner and whose crystal structure has been determined. This core is flanked at the N-terminus by the transcriptional transactivation domain and at the C-terminus by sequences involved in the oligomerisation of the protein. Extensive immunochemical analysis of p53 has shown that dominant antigenic sites lie within these N- and C-terminal domains while few antibodies to the central core have been identified. One of these, PAb240, has been extensively characterised as its epitope is cryptic in the native DNA binding core structure but is exposed by denaturation. This epitope is also exposed on many p53 proteins that contain point mutations in the core domain suggesting that these mutations may have a common affect on the structure of the core. To investigate this further we have generated several new antibodies to novel sites on p53 and mapped their epitopes using synthetic peptides. We find that antibodies to two other discrete sites in the core can also, like PAb240, recognize cryptic epitopes and distinguish mutant from wild-type conformations implying that the point mutations found in p53 in human tumours have widespread effects on the folding pattern of the DNA binding domain.

Amino Acid Sequence↗
PubMed1995

Absence of p53 autoantibodies in a significant proportion of breast cancer patients.

We analysed antibodies specific for human p53 in sera from primary breast cancer patients using three different immunoassays and we related these results to the p53 level in tumour tissue detected by immunohistochemistry. Only 44% (11/25) of apparently enzyme-linked immunosorbent assay (ELISA)-positive sera were from patients with a high level of p53 protein in more than 50% of their tumour cells. Surprisingly, 36% (9/25) of the sera originated from patients with no detectable p53 protein at all. Immunoprecipitation data suggested that the reason for this discrepancy is that at least some of the antibodies detected as positive in the ELISA in these sera from patients with clinical stage I and stage II breast cancers may be induced by immunogens other than p53 protein. Many of these reactions give apparently positive signals in a variety of p53 assays, and very stringent analysis is required to avoid possible misinterpretation of these responses as a p53-specific B-cell response in human cancer patients.

Autoantibodies↗
PubMed1994

Breast feeding and acute lower respiratory infection.

The association between breast feeding and acute lower respiratory infection (ALRI) was studied in a case-control study in southern Italy. Two groups of children were studied: the first group comprised 73 infants, aged 0-6 months, whose diagnosis was pneumonia or bronchiolitis; the second group included 88 infants less than 12 months of age with a diagnosis of pertussis-like illness. Control infants were two groups of infants admitted to the same ward. Compared with controls, infants in the first group were less likely to have been breast fed (odds ratio 0.42, 95% CI 0.19-0.90). The protection conferred by breast feeding was stronger among infants who were receiving human milk at the time of admission (odds ratio 0.22, 95% CI 0.09-0.55) and was absent among those infants who had stopped breast feeding for two or more weeks before admission. Among infants who were severely ill, breast feeding was less likely than among those with milder illnesses. There was evidence in the stratified analysis of effect modification by the presence of other children in the family. Among the infants with pertussis-like illness, the incidence and duration of breast feeding were not different compared with controls. The results suggest that breast feeding has a strong protective effect against ALRI in industrialized countries also. No protection seems to be conferred by human milk against pertussis-like illness.

Acute Disease↗
PubMed1985

[Radiology in chronic constipation in childhood].

One hundred thirteen children referred for chronic constipation were examined by means of diagnostic work-up including anal inspection, rectal exploration, weekly bowel frequency evaluation, measurement of total and segmental intestinal transit times (TITT, SITT), contrast enema, anorectal manometry (ARM), suction rectal biopsy for histochemistry. Final diagnosis were: chronic functional "simple" constipation in 53 children; chronic functional constipation and soiling in 32; Hirschsprung's disease in 18. In 10 children, initially referred for constipation, TITT was in the normal range so they underwent no further examination. Conclusions are that bowel frequency identifies a real gastrointestinal problem, but definite diagnosis of constipation is relied on TITT. In the assessment of chronic constipation nature, ARM is more sensitive than radiology. Suction rectal biopsy is reliable in detection of aganglionosis: its accuracy can be improved by histochemical or biochemical determination of Acetylcholinoesterase.

Acetylcholinesterase↗
PubMed1979

Monoacylcadaverines in schizophrenia.

Monoacetylcadaverine and monopropionylcadaverine were found in the blood of schizophrenic patients in higher concentrations than in the blood of nonschizophrenic subjects. The blood levels of both monoacylcadaverines in schizophrenics were relatively higher during exacerbation of the illness and were relatively lower during improvement.

Acylation↗
PubMed1978

Monoacylcadaverines in the blood of schizophrenic patients.

Concentrations of cadaverine, monoacetylcadaverine and monopropionylcadaverine in the blood of schizophrenic and nonschizophrenic subjects were measured. Two groups, one from the U.S.A. the other from Japan, were tested. Monoacetylcadaverine and monopropionylcadaverine were found elevated in the blood of some schizophrenic patients in comparison with those in controls in each group. Their increase could be caused by a reduced monoamine oxidase activity or by an increased acylation in schizophrenic patients.

Adult↗