Co-suppression of beta-1,3-glucanase genes in Nicotiana tabacum.
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Crosses, Genetic↗
Biomedical subjects
M Cornelissen
Publications and source records attributed to M Cornelissen.
Analysis of human immunodeficiency virus type 1 LTR-LTR junctions in peripheral blood mononuclear cells of infected individuals.
Circularized DNA species containing two long terminal repeat circle junctions were analysed in peripheral blood mononuclear cells of human immunodeficiency virus type 1 (HIV-1)-infected individuals. The circle junction fragments found could be classified into four groups: fragments containing a normal circle junction, fragments with deletions at the circle junction, fragments containing the primer binding site inserted at the circle junction, and fragments containing insertions at the circle junction derived from other regions of the HIV-1 genome.
Base Sequence↗
Subgenomic RNAs mediate expression of cistrons located internally on the genomic RNA of tobacco necrosis virus strain A.
Upon infection of tobacco protoplasts, the genomic RNA of tobacco necrosis virus strain A (TNV-A) accumulates linearly in time. The accumulation patterns of the two subgenomic RNAs resemble those of endogenous mRNAs in that the peak levels are reached after several hours. The accumulation of the 1.3-kb subgenomic RNA is delayed by 1 h compared with that of the 1.6-kb subgenomic RNA, which illustrates the important role of the subgenomic RNAs in the regulation of TNV-A gene expression. The locations of the 5' nucleotides of the subgenomic RNAs reveal that the 5'-proximal cistrons of the 1.6- and 1.3-kb RNAs encode an 8-kDa protein from open reading frame (ORF) 3 and the coat protein from ORF 5, respectively. In a wheat germ translation system, a synthetic transcript resembling the 1.6-kb RNA expresses both ORFs 3 and 4. Moreover, the synthesis of the 6-kDa protein from ORF 4 depends on the translation efficiency of ORF 3, suggesting that in vivo, ORFs 3 and 4 are both expressed from the 1.6-kb RNA. The major in vitro translation product of TNV-A genomic RNA is the coat protein. We show that the region upstream of the coat protein promotes internal initiation of translation in vitro. However, this region is functionally inactive in vivo, suggesting that TNV-A genomic RNA is not important for coat protein synthesis in plants.
Base Sequence↗
Stimulation of lysosomal enzymes in embryonic cartilage cells after ionizing irradiation.
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Acid Phosphatase↗
Analysis of chromosome aberrations and sister chromatid exchanges in peripheral blood lymphocytes of newborns after vitamin K prophylaxis at birth.
In many countries vitamin K prophylaxis at birth is recommended to prevent bleeding in infants due to vitamin K deficiency. Because the incidence of clinical vitamin K deficiency is very low, such a vitamin K administration should be completely safe. However, an increase in sister chromatid exchanges in lymphocytes of fetal sheep 24 h after injection of vitamin K1 has been reported. Therefore, a study concerning genotoxicity of vitamin K1 in man was conducted. Sister chromatid exchanges and chromosome aberrations were analyzed in peripheral blood lymphocytes of six newborns 24 h after intramuscular administration of 1 mg vitamin K1 and in six control neonates. The mean number of sister chromatid exchanges per metaphase in the vitamin K group was 8.88 +/- 1.22 as compared with 9.05 +/- 1.14 in the control group (NS). The mean number of chromosome aberrations per 100 mitoses was 3.00 +/- 2.61 in the vitamin K group and 2.50 +/- 1.87 in the control group (NS). Vitamin K1 plasma concentrations ranged from 115 to 1150 ng/mL (255 to 2555 x 10(-9) M) in the supplemented group, a 5000-fold rise as compared with the control group (p less than 0.01). We did not find any evidence for genetic toxicity due to the administration of 1 mg vitamin K1 intramuscularly to the newborn child.
Case-Control Studies↗
Induction of drug metabolism enzymes by dihalogenated biphenyls.
The effects of pretreatment with symmetrically dihalogenated biphenyls (DXBs, X-F, Cl(C), Br(B) and I) on rat liver drug metabolism enzymes were investigated. 4,4'-DFB, -DCB, and -DBB as well as 2,2'-DFB appeared to be inducers of microsomal cytochrome P-450-linked monoxygenases (N-demethylases of aminopyrine and ethylmorphine). However, no structure-induction relationship was found. 4,4'-DXBs also induced a cytochrome P-448-linked mono-oxygenase (ethoxyresorufin O-deethylase), and their order of induction potential seemed to parallel the increase of the size of the halogen substituent. Therefore, 4,4'-DXB's may be categorized as mixed-type inducers, the cytochrome P-450 component being the more pronounced. Data on the cytochrome P-448 induction by dihalogenated biphenyls with only para substituents may be considered as a refinement of the previously described structure-activity relationship in this respect. All of the DXBs except 3,3'-DCB and 4,4'-DIB, enhanced, like phenobarbital, the activity of UDP-glucuronyltransferase toward 4-hydroxybiphenyl. Only 4,4'-DFB was able to induce the activity of glutathione S-transferase toward 1,2-epoxy-3-(p-nitrophenoxy)propane. Studies after 4,4'-DBB-treatment revealed, like phenobarbital, a preferential induction of ethylmorphine N-demethylase on rough endoplasmic reticulum-derived microsomes, whereas UDP-glucuronyltransferase activity toward 4-hydroxybiphenyl was induced to a larger extent on smooth endoplasmic reticulum microsomes, suggesting a dissimilar enzyme induction in microsomal subfractions.
Animals↗
Dose- and time-dependent radiation inhibition of RNA and glycosaminoglycan synthesis in embryonic cartilage: an in vitro study.
Radiation effects on the RNA and glycosaminoglycan (GAG) synthesis of embryonic cartilaginous tibiae were studied in vitro during a 4- or 7-day culture period. Before being cultured, tibiae received single radiation doses of 20, 50 or 100 Gy. The counterparts served as sham-irradiated controls. At different times after irradiation, irradiated and control tibiae were pulse-labelled for 2 h with [3H]uridine or [3H]glucosamine. The incorporated radioactivity was measured by liquid scintillation counting. Histochemical demonstration of acid phosphatase (AP), a lysosomal enzyme, was carried out using beta-glycerophosphate as substrate. A limited, dose-dependent immediate effect on RNA and GAG synthesis was found. This effect was unchanged for 2 days. After this period a time-dependent delayed effect was observed. For each radiation dose, and for each precursor, the same time-related pattern was found. At the end of the culture period AP activity, an early indicator for apoptosis, was higher in the irradiated tibiae than in the controls. No other morphological ultrastructural differences were observed at this time. We conclude that the metabolic alterations are probably due to stimulation of the initial stages of the apoptotic process in the irradiated cartilage cells.
Animals↗
Dose- and time-dependent increase of lysosomal enzymes in embryonic cartilage in vitro after ionizing radiation.
Radiation doses of 20, 50 or 100 Gy caused the same time related decrease for RNA and proteoglycan (PG) synthesis in embryonic cartilage in vitro (4 days culture). In this paper, participation of lysosomes in this radiation response is investigated. Therefore, we employ a cytochemical method using beta-glycerophosphate as substrate for acid phosphatase (AP) detection. Increase of AP was found 2 days after irradiation and increased during the whole culture period. The increase was more pronounced with a higher radiation dose. Stimulation of AP activity explains the observed radiation response of RNA and PG synthesis.
Acid Phosphatase↗
Nuclear and cytoplasmic sites for anti-sense control.
In transgenic tobacco, anti-sense control of the chimaeric bar (bialophos resistance) gene is manifested by a reduced bar transcript level and a reduced synthesis of bar translational product (PAT, phosphinothricin acetyl transferase) per transcript (1). This study shows that the anti-bar gene controls the transcript level and the translation efficiency of the bar mRNA through independent events and at different cellular sites. On the basis of these results a model for the mechanism of anti-sense control is proposed.
Cell Nucleus↗
Both RNA level and translation efficiency are reduced by anti-sense RNA in transgenic tobacco.
The effect of anti-sense RNA on the expression of the bialaphos resistance (bar) gene which encodes phosphinothricin acetyl transferase (PAT), was analysed in tobacco. Transient expression studies revealed that an anti-bar RNA with sequence complementarity to the complete bar coding region, inhibits PAT synthesis. To quantify the phenomenon, SR1 tobacco cells were transformed twice to introduce first a hybrid bar gene with a reporter gene and in a second instance an anti-bar gene. A first cycle transformant and a double transformant derived herefrom in which PAT synthesis was reduced to only 8%, were studied in detail. The interference of the anti-sense gene with the expression of the bar gene is manifested at least two levels. First, the bar mRNA steady state level is significantly reduced relative to the parental whereas the transcript level of the reporter gene is unchanged. Comparison of bar mRNA levels in total and single stranded (ss) RNA preparations demonstrated that little if any stably base-pairing bar and anti-bar RNA accumulates. Secondly, a three fold reduction of PAT synthesis per bar mRNA is observed. This supposes that because of unstable interactions with the complementary anti-bar RNA either a substantial part of the bar mRNA detected does not enter the cytoplasm and/or that in the cytoplasm the bar mRNA is less efficiently translated. It is not clear if or how the reduced bar mRNA level is related to such unstable interactions.
Acetyltransferases↗
Nuclear transcriptional activity of the tobacco plastid psbA promoter.
The plastid psbA promoter of tobacco was used with the aim to construct plastid specific marker genes. Upon transfer to the tobacco nuclear genome the plastid promoter fragment appeared to specify a messenger RNA. Placed 5' to the bar or nptII coding sequences the level of expression is sufficient to obtain a selectable phenotype. The transcription start site in the nucleus is site specific and is located 4 nucleotides downstream relative to the start site used in plastids. Translational fusions of the psbA coding sequence with the nptII and bar coding sequences revealed that the psbA leader sequence and the psbA translation start codon, being the second ATG codon, are recognized by the plant cytoplasmic translation apparatus. A promoter cassette utilisable in both E. coli and tobacco, was obtained by placing the CaMV 35S enhancer 5' to the psbA promoter.
Base Sequence↗
Computer assisted pantropic urethral pressure profile.
A computerized method for urethral pressure measurement along the whole length and at every angle of the urethra is presented. The main advantage is the exact study of physiological versus artificial factors in pressure distribution in the urethra. Details of the technique are presented.
Diagnosis, Computer-Assisted↗
Effects of ionizing radiation on the metabolism and longitudinal growth of cartilaginous embryonic chick tibiae in vitro.
The effect of ionizing radiation on the metabolism and longitudinal growth of cartilaginous tibiae of 6.5-day-old chick embryos was studied in vitro over a 3-day period. Before being cultured, tibiae received absorbed doses of 2 to 200 Gy. Of each pair, the counterpart served as control. Compared to the strong inhibition of [3H]thymidine incorporation, already 50 percent at 10 Gy, the effects of ionizing radiation on [3H]uridine and [3H]proline incorporation were limited: 20 and 40 percent respectively at 150 Gy. Metabolism of the cartilage cells in our organ culture was almost completely arrested at 200 Gy. Light and electron microscopy showed no morphological differences between irradiated and sham-irradiated tibiae until 150 Gy. At 200 Gy necrosis of most of the cells was observed. No differences in form and arrangement of extracellular fibers were noticed. The results of the metabolic studies and the morphological observations were correlated with the effects of ionizing radiation on the longitudinal growth. In contrast to DNA synthesis, RNA transcription and synthesis of collagen fibres were radioresistant processes.
Animals↗
Assessment of tibial stiffness by vibration testing in situ--III. Sensitivity of different modes and interpretation of vibration measurements.
Post mortem vibration measurements on one human tibia during gradual transection reveal the vibration modes and frequencies of a tibia during a simulated healing. The modes are identified in a tibia in an above knee amputation specimen with the leg in two positions: hanging down with the knee flexed (90 degrees) and supported in a special designed bone clamping splint (knee flexed 45 degrees). The vibration measurements are analysed using Modal Analysis and are translated to mechanical stiffness by mathematical modelling. The single bending 'free-free' mode turned out to be more sensitive to weakening of one cross-section than the 'rigid body' and single bending 'hinged-spring' modes. The error on the assessed value of the stiffness is a multiple of the error on the measured frequencies. This multiplication factor decreases for more sensitive modes. In this experiment, the results are accurate enough to reflect the asymmetric weakening imposed upon the tibia. Attempts are made towards automatization of the measurement and analysis in order to get a system for clinical use. The actual system is still too cumbersome and time consuming for standard clinical use.
Humans↗
Iatrogenic ureteral injury: aggressive or conservative treatment.
Many different approaches are advocated for management of iatrogenic (operative) ureteric injury. We herein report our experience with 28 ureteral injuries in 26 patients. In six patients, seven injuries were recognized at the time of the initial operation; four end-to-end anastomoses and three ureteroneocystostomies were successfully performed. In 20 patients the diagnosis of injury was delayed. In 14 of them a ureteroneocystostomy with or without Boari bladder flap was performed. The other six patients were first treated by percutaneous nephrostomy, which was successful in only two cases. The other four needed subsequent operative management. The main point that has emerged from our review is that early definitive operative repair is both feasible and preferable.
Adult↗
Assessment of tibial stiffness by vibration testing in situ--I. Identification of mode shapes in different supporting conditions.
Vibrational methods to monitor fracture healing, the BRA and the IFR, are compared under different supporting conditions, excitation technique and signal processing. Mode shapes are identified by modal analysis. A wet excised human tibia and an amputation specimen are investigated. Excitation technique and signal processing caused only minor differences in the resonance frequencies. The supporting conditions had an important influence on the single bending modes changing both mode-shapes and frequencies. Thus the BRA-splint imposed a node at the malleolus. Modal analysis revealed the following modes in the two supporting conditions: BRA-splint: A 'rigid body' mode of 165 Hz in the sagittal plane. A single bending mode of 315 Hz close to the sagittal plane. IFR-hanging leg: A 'rigid-body' mode of 167 Hz close to the sagittal plane. Two single bending modes ('free-free'), a mode of 303 Hz close to the frontal plane and a mode of 470 Hz in the sagittal plane.
Biomechanical Phenomena↗
Assessment of tibial stiffness by vibration testing in situ--II. Influence of soft tissues, joints and fibula.
The influence of soft tissues and joints on the vibration of the human tibia was examined by modal analysis on amputated lower limbs, where the soft tissues and the fibula were dissected gradually. Measurements were made in two different set ups, IFR and BRA, which were both designed to monitor fracture healing. In IFR, vibrations are generated by hammer impact on a relaxed hanging lower leg, with the knee flexed. Resonant frequencies are determined by a computer Fourier transform procedure. In BRA, a steady state vibration is induced in a lower leg, supported near the ankle and the tibial tuberosity, using an electromagnetic shaker. Resonant frequencies are determined from the maxima in vibration amplitudes. In both set ups the soft tissues have a similar influence on the vibration of the tibia: the skin hardly influences the determined modal parameter. The mass of the muscles influences both the resonant frequency and the damping. The fibula has a stiffening effect on the tibia. The influence of the joints is small in the IFR-set up: the tibia vibrates in conditions close to those for the free-free vibration. In the BRA-set up, the supports determine the boundary conditions.
Biomechanical Phenomena↗
Bacteriological effect of cerium-flamazine cream in major burns.
A controlled trial of the use of either 0.05 per cent chlorhexidine for bathing burn wounds or the topical application of a cream containing cerium nitrate and silver sulphadiazine showed that the cerium-flamazine cream significantly reduced the degree of Pseudomonas aeruginosa contamination of the burn wounds of patients with burns covering more than 15 per cent of the body surface area. The adherent eschar produced by treatment with cerium-flamazine provided a satisfactory wound cover until tangential excision could be carried out.
Administration, Topical↗