Multiple H4 histone mRNAs of HeLa cells are encoded in different genes.
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Base Sequence↗
Biomedical subjects
F Sierra
Publications and source records attributed to F Sierra.
Histone proteins in HeLa S3 cells are synthesized in a cell cycle stage specific manner.
The synthesis of histone proteins in G1 and S phase HeLa S3 cells was examined by two-dimensional electrophoretic fractionation of nuclear and total cellular proteins. Newly synthesized histones were detected only in S phase cells. Histone messenger RNA sequences, as detected by hybridization with cloned human histone genes, were present in the cytoplasm of S phase but not G1 cells.
Cell Cycle↗
Human histone genes are interspersed with members of the Alu family and with other transcribed sequences.
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Bacteriophage lambda↗
Analysis of histone gene expression during the cell cycle in HeLa cells by using cloned human histone genes.
Although it is generally agreed that histone protein synthesis is restricted to the S phase of the cell cycle--and therefore parallels DNA replication--both transcriptional and posttranscriptional levels of control have been invoked. Using blot hybridization with several cloned genomic human histone sequences representing different histone gene clusters as probes, we have assessed the steady-state level of histone RNAs in the nucleus and cytoplasm of G1 and S phase HeLa S3 cells. The representation of histone mRNA sequences of G1 compared with S phase cells was less than 1% in the cytoplasm and approximately 1% in the nucleus. These data are consistent with transcriptional control, but we cannot completely dismiss the possibility that regulation of histone gene expression is, to some extent, mediated posttranscriptionally. If histone gene transcription does occur in G1, the RNAs must either be rapidly degraded or be transcribed to a limited extent compared with S phase. An unexpected result was obtained when a blot of cytoplasmic RNA from G1 and S phase cells was hybridized with lambda HHG 41 DNA (containing H3 and H4 human genomic histone sequences). Although hybridization with histone mRNAs was observed for RNAs from S phase but not from G1 cells, hybridization with a nonhistone RNA of approximately 330 nucleotides present predominantly in G1 was also observed.
Bacteriophage lambda↗
Organization of human histone genes.
We describe the isolation and initial characterization of seven independent lambda Charon 4A recombinant phages which contain human histone genomic sequences (designated lambda HHG). Restriction maps of these clones and localization of the genes coding for histones H2A, H2B, H3, and H4 are presented. The presence of histone encoding regions in the lambda HHG clones was demonstrated by several independent criteria including hybridization with specific DNA probes, hybrid selection/in vitro translation, and hybridization of lambda HHG DNAs to reserve Southern blots containing cytoplasmic RNAs from G1-, S-, and arabinofuranosylcytosine (cytosine arabinoside)-treated S-phase cells. In addition, the lambda HHG DNAs were shown to protect in vivo labeled H4 mRNAs from S1 nuclease digestion. Based on the analysis of the lambda HHG clones, human histone genes appear to be clustered in the genome. However, gene clusters do not seem to be present in identical tandem repeats. The lambda HHG clones described in this report fall into at least three distinct types of arrangement. One of these arrangements contains two coding regions for each of the histones H3 and H4. The arrangement of histone genes in the human genome, therefore, appears to be different from that in the sea urchin and Drosophila genomes in which each of the five histone-encoding regions (H1, H2A, H2B, H3, and H4) is present only once in each tandemly repeated cluster. At least one clone, lambda HHG 41, contains, in addition to the histone genes, a region that hybridizes with a cytoplasmic RNA approximately 330 nucleotides in length. This RNA is not similar in size to known histone-encoding RNAs and is present in the cytoplasm of HeLa cells predominantly in the G1 phase of the cell cycle.
Bacteriophage lambda↗
Two molecular approaches for identification of human genomic sequences whose expression is functionally coupled with DNA replication.
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Base Sequence↗
Pathogenesis of paracoccidioidomycosis: a model based on the study of 46 patients.
Forty-six Paracoccidioidomycosis patients were studied with emphasis on lung pathology. It was found that the greatest clinical involvement of the reticuloendothelial system occurred in younger individuals. On the other hand, the frequency of tegumentary lesions was low in young patients and increased with age. Lung involvement was nearly always demonstrated when searched for and showed no relationship to the patient's age. In the young patients the disease was acute while in the older individuals its course was chronic. The findings from this study permitted formulation of a model for the pathogenesis of paracoccidioidomycosis in which the respiratory tract is accepted as the primary site of infection. Based on this model, a classification of the various forms of the entity is proposed.
Adolescent↗
The gamut of paracoccidioidomycosis.
Paracoccidioidomycosis is a systemic mycosis of importance in Latin America. Because of its polymorphic manifestations, it is not always suspected and patients are sometimes misdiagnosed. Case histories of patients with paracoccidioidomycosis are presented in order to illustrate its various manifestations, with emphasis on the primary pulmonary localization.
Acute Disease↗
[Blood volume changes and oxygenation during labor--a laser spectroscopic analysis].
BACKGROUND: Hemodynamic patterns and the distribution of blood volume are influenced by the onset of labour. This study evaluates patterns of oxygenation and changes of blood volume after the induction of contractions. METHODS: A prototype NIR-laser spectrometer was applied in 28 cases. RESULTS: We found a rise of blood volume and oxygen saturation (HbO2) during the peak of contractions. Cerebral tissue oxygenation was monitored by registration of relative changes of cytochrome-aa3. No significant change of tissue oxygenation was detected during variable volume load. DISCUSSION: This implicates compliance of the redox state during labour.
Blood Volume↗
[Effect of modified labor posture on oxygenation of the fetus--a pulse oximetry study].
BACKGROUND: The evaluation of the birth position and its effects on maternal and fetal wellbeing has been a topic of perinatal research over the last decades. The aim of our observational study was to determine the effects of a modified and vertical maternal position on fetal oxygen saturation measured by pulse oximetry. METHODS: Fetal oxygen saturation was measured by pulse oximetry in 56 labouring women randomly and successively adopting the supine position in 96.4%, the sitting position in 25.0%, the standing position in 14.3% and the prone position in 12.5%. The statistical analysis addressed the integrated 10 minutes period of SpO2 registrations before versus after adopting the modified position. Furthermore the mean values and the standard deviation (SD) for the total registration periods of different birth position was calculated. RESULTS: While the supine position induced a reduction in oxygen saturation, sitting and prone position were favorable for fetal oxygenation as compared to horizontal position. DISCUSSION: These findings implicate a clinical benefit of the modified birth position.
Adult↗
[Quantitative ultrasonic tissue characterization of the cervix - A new predictor for prematurity?].
BACKGROUND: Since the incidence of premature delivery has remained constant for the last decade despite intensive safeguarding methods, the texture features of the uterine cervix were evaluated using quantitative sonographic gray level analysis at different gestational ages. MATERIALS AND METHODS: For this purpose, quantitative ultrasonic tissue densitometry of the uterine cervix was obtained from 30 asymptomatic female patients (group A, mean: 30,3 GA) and compared with values obtained from 16 symptomatic female patients (group B, mean: 29,5 GA) with uterine contractions and shortening of the cervix at similiar gestational ages. Once the two-dimensional transvaginal sonographic measurement of cervical length was completed, a region of interest of constant size was defined in the mid-section of the posterior wall, and the tissue-specific gray scale distribution was determined. RESULTS: Quantitative ultrasonic tissue characterization of uterine cervix was feasible in all 46 patients at all gestational ages. In patients with premature contractions and shortening of cervix the average gray scale values were found to be significantly reduced in comparison with those obtained from asymptomatic patients. These results showed good reproducibility and low intraobserver variability and were found to be independent of the measured cervical length. CONCLUSION: Our results prove that quantitative ultrasonic tissue characterization of the uterine cervix might serve as a new parameter for predicting premature delivery.
Adult↗
[Evaluation of the reproducibility of Doppler ultrasonographic measurements in obstetrics].
BACKGROUND: Are obstetric doppler ultrasonographic measurements of the fetal and maternal flow parameters reproducible? PATIENTS AND METHODS: For internal quality management, doppler ultrasonographic measurements were performed on 81 patients (random screening sample) with an Acuson Sequoia Ultrasound at the Universitätsfrauenklinik Marburg. Successively two experienced investigators measured the umbilical artery, medial cerebral artery, and the uterine arteries. The correlation between the measurements of the two investigators was presented in a spread chart. In order to exclude systematic differences between the measurements, linear regression was analyzed and the distance to the abscissa was calculated. A relative divergence of more than 20% was determined as a non corresponding measurement. RESULTS: The distance of the linear regression to the abscissa was calculated for the four vessels: umbilical artery 0.4 (95% CI; 0.124 - 0.486), medial cerebral artery 0.9 (95% CI; 0.534 - 1.264), right uterine artery 0.2 (95% CI; 0.124 - 0.305), and left uterine artery 0.2 (95% CI; 0.121 - 0.317). Concerning the four arteries, a divergence of more than 20% between the two investigators was found: umbilical artery 16%, medial cerebral artery 42%, right uterine artery 28%, and left uterine artery 37%. CONCLUSIONS: Because the interobserver variability was surprisingly high and acceptable correlation could be stated only for the umbilical artery, internal quality standards are essential. Routine use of different devices should be made after careful consideration only, especially if clinical decisions are to be based on them.
Blood Flow Velocity↗