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Biomedical subjects

E Barnea

Publications and source records attributed to E Barnea.

At least 19 recordsLinked to original sources
PubMed2006

[Full arch impression techniques utilizing addition type poly vinyl siloxane for fabrication of tooth born fixed partial dentures].

A precise impression is necessary for fabricating an accurately fitting cast restoration. For this purpose, Polyvinyl Siloxane (PVS) impression materials are extremely popular because of their combination of excellent physical properties, handling characteristics and dimensional stability. Its excellent clinical features remain unaffected if simple measures are guarded. This review presents several impression techniques using PVS and recommends the one that provides the most accurate impression, utilizing the superior qualities of the PVS. The one step impression technique where no control of wash bulk and thickness exists, is considered to be the least accurate impression method with measured discrepancies as large as 7 times the original inter preparation distance and 40 times the original cross arch dimensions. Furthermore, the direct contact between the less refined putty material and the tooth preparation, as well as the high prevalence of air bubble entrapment, seriously compromises restoration longevity. The two stage impression technique has proved to produce the most accurate and reliable impressions due to complete control of the wash bulk and thickness entailed. The ideal wash bulk thickness should range between 1 to 2.5 mm all around the abutment tooth in order to minimize distortion of its subsequent die. Using a "Putty Tray" at the first stage with a predetermined space encircling the abutments will allow the wash to flow to its ideal uniform bulk size at the second stage. A uniform bulk size will prevent differential setting contraction and uneven changes at the dimensions of the die. The easiest and most clinically applicable method to achieve the desired space around the preparations is by loading the Putty material with the temporary crowns in place, followed by their removal at the second stage and occupation of the created space by the wash. In general, less control of wash bulk will result in either insufficient or excessive wash material which will determine uneven dimensional changes in the impression. This, in turn, will produce ill fitting cast restoration.

Dental Impression Materials↗
PubMed2003

Relationship between occlusal plane determinants and craniofacial structures.

A cephalometric study was conducted on 34 complete denture wearers to investigate the relationship between the anatomical structures commonly used to determine the occlusal plane and the facial skeletal shape. The results showed no correlation between the shape of the skeletal face, the gonial angle and the length of the mandible versus the location of the retromolar pad, the occlusal plane and Camper's plane. However, a statistically significant linear correlation (P < 0.0001) was found between the facial skeletal shape designated SN POG and the location of Camper's plane. Cephalometric analysis alone cannot determine the location of the occlusal plane in edentulous patients. Intra-oral structures should also be considered.

Aged↗
PubMed2003

Relationship between the craniofacial complex and size of the resorbed mandible in complete denture wearers.

A cephalometric study was conducted on 34 complete denture wearers to examine the relationship between the area of the mandible and the skeletal facial form, the area of the mandible and the gonial angle, and the area of the mandible and the length of the mandible. No significant correlation was found between the area of the mandible and the skeletal facial types or the gonial angle. A statistically significant correlation (P < 0.0028) was found between the length of the mandible and the area of the mandible. Residual resorption of the mandible appears to be independent of skeletal facial form and the gonial angle.

Aged↗
PubMed2000

Synergy of SF1 and RAR in activation of Oct-3/4 promoter.

The Oct-3/4 transcription factor is expressed in the earliest stages of embryogenesis, and is thus likely to play an important role in regulation of initial decisions in development. For the first time, we have shown that SF1 and Oct-3/4 are co-expressed in embryonal carcinoma (EC) P19 cells, and their expression is down-regulated with very similar kinetics following retinoic acid (RA) induced differentiation of these cells, suggesting a functional relationship between the two. Previously, we have shown that the Oct-3/4 promoter harbors an RA-responsive element, RAREoct, which functions in EC cells as a binding site for positive regulators of transcription, such as RAR and RXR. In this study we have identified in the Oct-3/4 promoter two novel SF1-binding sites: SF1(a) and SF1(b). The proximal site, SF1(a), is located within the RAREoct, and the distal site, SF1(b), is located between nucleotide -193 and -209 of the Oct-3/4 promoter. Both sites contribute to activation of Oct-3/4 promoter in EC cells, with SF1(a) playing a more crucial role. SF1, and its isoforms ELP2 and ELP3 bind to both SF1 sites and activate the Oct-3/4 promoter. This activation depends on the presence of SF1 DNA-binding domain. Thus, Oct-3/4 is the first EC-specific gene reported that is regulated by SF1. Interestingly, SF1 and RAR form a novel complex on the RAREoct sequence that synergistically activate the Oct-3/4 promoter. Both RARE and SF1 cis regulatory elements, as well as the SF1 DNA-binding domain, are needed for this synergism. SF1 and Oct-3/4 transcription factors play a role in the same developmental regulatory cascade.

Animals↗
PubMed1999

Daily scheduling of the golden spiny mouse under photoperiodic and social cues.

A most important function of the circadian system is to ensure that behaviors and metabolism are appropriately timed with respect to the light/dark cycle and photoperiod. Ecological constraints can perturb the daily schedules; would they also impair photoperiodic adaptations? A natural model exists in the golden spiny mouse (Acomys russatus), which is nocturnal, but driven into diurnal activity when sharing the habitat with its congener, A. cahirinus. We show here that the presence of A. cahirinus alters the diurnal rhythms of body temperature and urine volume, delays excretion of the major melatonin metabolite, 6-sulfatoxymelatonin (6-SMT), and increases 2-deoxyglucose uptake by the suprachiasmatic nuclei in A. russatus. Nevertheless, a clear photoperiod effect on urine volume and 6-SMT rhythms was observed. These results indicate that the circadian system can adapt to major changes in daily scheduling without impairing daylength measurement, and consequently seasonal adaptation.

Adaptation, Physiological↗
PubMed1998

Involvement of the pineal gland in daily scheduling of the golden spiny mouse.

The light-dark cycle is the major time cue for daily and seasonal scheduling of physiological activities. However, non-photic cues (e.g. environmental and social constraints) may also play a significant role. A natural model exists in the golden spiny mouse (Acomys russatus) which is nocturnal when maintained alone but diurnal when sharing a habitat with its congener, the common spiny mouse (A. cahirinus). We have recently observed that the presence of A. cahirinus provokes a major change in the daily rhythms of body temperature (Tb), and urine volume without affecting the melatonin rhythm and photoperiod-induced responses. The apparent lack of interaction between the daily and photoperiodic scheduling was further investigated by studying the significance of the pineal to the modification of A. russatus daily rhythms induced by the presence of A. cahirinus. Lesion of A. russatus pineal gland resulted in diminution of urinary 6-sulfatoxymelatonin (6-SMT) and modification of Tb and urine volume rhythms. However, the modification of Tb and urine volume rhythms provoked by the presence of A. cahirinus were similar in pineal lesioned and sham-operated A. russatus. The non-photic signals released by A. cahirinus did not significantly affect glucose utilization in the suprachiasmatic nucleus of pineal- as well as sham-lesioned A. russatus. Thus, the modification of the daily scheduling of A. russatus by the photoperiod involves the pineal and/or the melatonin rhythm whereas non-photic cues effect a direct (perhaps masking), pineal-independent response to the competitor.

Animals↗
PubMed1998

The effect of parafunction on condylar asymmetry in patients with temporomandibular disorders.

This study was undertaken to examine the relationship between condylar asymmetry and parafunction in patients with temporomandibular disorders (TMD). Twenty-eight patients with TMD and parafunction and 30 patients with TMD but no parafunction were examined. A panoramic radiograph was obtained for each patient and from this the condylar asymmetry determined. The group with parafunction showed a significantly (P < 0.005) higher asymmetry index than did the group with no noticeable parafunction. Patients were grouped into the following age ranges: 10-19 years, 20-29 years, 30-39 years, and 40 + years. The mean asymmetry index was determined for each age range for both groups of patients. The group of patients with TMD and parafunction had a higher mean asymmetry index in all the age ranges studied. This suggests that muscle hyperactivity may be a factor in the increased asymmetry found in patients with TMD.

Adolescent↗
PubMed1992

Multiple products of the Duchenne muscular dystrophy gene.

The gene which is defective in Duchenne Muscular Dystrophy (DMD) extends over 2300 kb of the X chromosome. Its product in the muscle is a 14 kb mRNA encoding a 427 kd rod-shaped protein called dystrophin. A 14 kb transcript encoding a very similar isoform of dystrophin is produced in the brain. The brain 14 kb mRNA is transcribed from the same gene but controlled by a different promoter, located at least 75 kb upstream from the muscle dystrophin promoter. The regulation of these promoters is very stringently controlled. The muscle-type but not the brain-type dystrophin mRNA is found in cloned skeletal muscle cells and its presence is correlated with the appearance of multinucleated fibers. The brain type is expressed in neurons, while in glia cells the muscle-type promoter is active. A third DMD gene transcript which is only 6.5 kb long has been identified. It contains the sequence coding for the C-terminal domain and the cysteine-rich domain of dystrophin but not the large region encoding the spectrin-like repeats and the N-terminal domain. The cell type distribution of this transcript is also very different from that of the two 14 kb mRNA isoforms. It is the major product of the DMD gene in many nonmuscle tissues including brain. Using monoclonal antibodies we have identified a 77 Kd protein which seems to be the translation product of this mRNA. As expected from the distribution of the 6.5 Kb mRNA, this protein is the major DMD gene product detectable in brain and many other nonmuscle tissues; it is undetectable in skeletal muscle but is present in the heart and stomach (as is the 6.5 Kb mRNA).

Base Sequence↗
PubMed1990

A novel product of the Duchenne muscular dystrophy gene which greatly differs from the known isoforms in its structure and tissue distribution.

A novel transcript of the Duchenne muscular dystrophy gene has been identified. This 6.5 kb mRNA contains sequences from the 3' untranslated region of dystrophin mRNA and from the regions coding for the C-terminal and the cysteine-rich domains. However, probes for the regions encoding the spectrin-like repeats and the actin-binding domain, as well as probes for the first exons of the muscle- and brain-type dystrophin mRNA, did not hybridize with this new mRNA. Significant amounts of the 6.5 kb mRNA were found in a variety of non-muscle tissues, such as liver, testis, lung and kidney, but not in skeletal muscle. The abundance of this mRNA in the brain is at least as high as that of the previously described 14 kb brain-type dystrophin mRNA.

Animals↗
PubMed1990

Specificity of expression of the muscle and brain dystrophin gene promoters in muscle and brain cells.

The gene that is defective in Duchenne and Becker muscular dystrophies is expressed in the muscle and brain. However, the 5' ends of the 14 kb mRNA in these tissues are derived from two different exons, indicating the involvement of at least two promoters in the regulation of the cell-type and developmental specificities of expression of this gene. In the study presented here, we used the polymerase chain reaction and RNAase protection methods and various cell cultures to investigate the specificities of expression of these promoters. The results indicate a very stringent control of expression of the two promoters. In cloned rat myogenic cells, only the muscle-type dystrophin transcript was detected, and its presence was correlated with the formation of multinucleated fibers. In neuronal cell cultures, the brain-type transcript was detected. However, glial cell cultures expressed the muscle transcript only. Some cell lines derived from brain cells expressed both isoforms.

Animals↗
PubMed1990

1,25-Dihydroxyvitamin D3 enhances cytosolic free calcium in HL-60 cells.

1,25-Dihydroxyvitamin D3 (1,25[OH]2D3) caused a rise in the concentration of intracellular free calcium ions ([Ca2+]i) in HL-60 cells. This effect of 1,25(OH)2D3 parallels its suppression of cell proliferation and its induction of cell differentiation into monocyte-like cells. The changes in [Ca2+]i are dose and time dependent. The concentration of 1,25(OH)2D3 (10(-7) M) that induced maximal differentiation also caused the maximal increase in intracellular Ca2+. The rise in cytoplasmic free Ca2+ concentration was not immediate and reached statistical significance only after 24 h. The [Ca2+]i reached its peak at 48 h (134 +/- 4 nM vs 101 +/- 3 nM in controls) and remained stable at this level. The increase in intracellular Ca2+ was found to be related to new protein synthesis, because it was inhibited in the presence of specific RNA and protein synthesis inhibitors. The rise in [Ca2+]i was not observed during incubation of HL-60 cells with 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), a vitamin D metabolite that does not induce the differentiation of HL-60 cells. In contrast, 25-hydroxyvitamin D3 (25-OH-D3) and phorbol 12-myristate 13-acetate (TPA), both of which induce differentiation in this cell line, also increase [Ca2+]i. In conclusion, the present study emphasizes that a significant increase in intracellular free Ca2+ occurs in the effect of 1,25(OH)2D3 on HL-60 cells.

Calcitriol↗
PubMed1988

The involvement of calcium ions in the effect of 1,25-dihydroxyvitamin D3 on HL-60 cells.

1,25-Dihydroxyvitamin D3 (1,25[OH]2D3) was found to suppress growth of human leukemic cells (HL-60), and to induce the differentiation of these cells to monocyte-like cells. The purpose of the present study was to examine the role of calcium ions in the effects of 1,25(OH)2D3 on HL-60 cells. Incubation of the HL-60 cells with 1,25(OH)2D3 (10(-7) M) for 4 days caused a significant inhibition of 50% of cell growth. The number of differentiated cells increased simultaneously from 24 x 10(3) +/- 2 x 10(3) in the controls to 658 x 10(3) +/- 32 x 10(3) in the 1,25(OH)2D3 (10(-7) M)-treated cells. The role of calcium ions in the effects of 1,25(OH)2D3 on HL-60 cells was first studied by changing the available calcium in the medium and by measuring the effect of 1,25(OH)2D3 on intracellular Ca2+ levels. Limitation of the available Ca2+ by means of ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) or verapamil enhanced the inhibitory effect on proliferation and decreased the number of differentiated cells obtained by 1,25(OH)2D3 alone. These effects could be abolished by restoring the Ca2+ levels. The role of the intracellular free Ca2+ ions in the effect of 1,25(OH)2D3 was further illustrated by measuring the intracellular Ca2+ levels. The intracellular free Ca2+ concentration in 1,25(OH)2D3 (10(-7) M)-treated HL-60 cells rose significantly from 117.0 +/- 6.3 nM in the untreated HL-60 cells to 145.0 +/- 7.5 nM in the treated cells (p less than 0.02). Addition of verapamil moderated the increase in intracellular free Ca2+ (125.0 +/- 5.2 nM) obtained by 1,25(OH)2D3 alone. Thus the elevation of intracellular free Ca2+ caused by 1,25(OH)2D3 treatment may be involved in the effect of the hormone on the HL-60 cells.

Calcitriol↗
PubMed1986

Characterization of glycoprotein hormone free alpha-subunit from human pituitary and placenta extracts.

Standard alpha-subunit dissociated from glycoprotein hormones differs from individual (free) alpha-subunit found in sera or in cell culture media; secreted free alpha-subunit is larger, more acidic and lacks the ability of recombining in vitro with standard hCG-beta. It is unclear whether the large free alpha-subunit is only a secretory product or whether it is also present in tissue. Herein were studied the molecular size, the isoelectric pH, and the recombining activity of free alpha-subunit obtained from pituitary and placenta extracts. Sephadex exclusion chromatography showed the presence of both a large and a small form, and a changing large/small free alpha-subunit ratio in the various extracts. Most of the large form obtained from placenta extracts electrofocused into two peaks of pI 4.8 and 5.1. The large form showed no recombining activity with standard hCG-beta while the small free alpha-subunit recombined as well as did standard hCG-alpha. The observation of three common characteristics (a larger size, a pI 4.8, and a lack of recombining activity) suggests a similarity between the large secreted form and a fraction of the free alpha-subunit in tissue.

Chromatography, Gel↗
PubMed1986

Are catechol oestrogens obligatory mediators of oestrogen action in the central nervous system? I. Characterization of pharmacological probes with different receptor binding affinities and catechol oestrogen formation rates.

In an attempt to define pharmacological probes with which to test the role of catechol oestrogen formation in the central nervous system, five oestrogens (oestradiol-17 beta, oestradiol-17 alpha, 4-fluoro-oestradiol, 2-fluoro-oestradiol and moxestrol (11 beta-methoxy-17 alpha-ethynyloestradiol) were studied for binding to oestrogen receptors and conversion to catechol metabolites. Binding to cytosol oestrogen receptors was measured in the hypothalamus-preoptic area-amygdala (HPA), pituitary gland and uterus of ovariectomized rats. Conversion to catechol oestrogens was tested in microsomes from the HPA, pituitary gland and liver, using a catechol-O-methyltransferase-coupled radioenzymatic assay. Oestradiol-17 alpha was the only weak oestrogen receptor ligand. Binding affinities of the other compounds tested were much higher and comparable to those of oestradiol-17 beta. In contrast, oestradiol-17 alpha was rapidly converted to catechol metabolites, while moxestrol was a relatively poor substrate for catechol oestrogen formation. 4-Fluoro-oestradiol could be 2-hydroxylated but not 4-hydroxylated. 2-Fluoro-oestradiol exhibited impaired 2-hydroxylation but normal 4-hydroxylation.

Animals↗
PubMed1980

New vacuum stethoscope for immediate monitoring and recording of resuscitation of the newborn.

A new, low-cost, noninvasive system is described, which accurately monitors and records both the initial respirations and heart rate of the neonate during resuscitation and the first critical seconds of life. The apparatus consists of a vacuum stethoscope attached to an ordinary cassette tape recorder and a 12-inch loudspeaker. The system was found to be a more accurate tool for assessing neonatal heart rate than the empirical estimation as part of the Apgar scoring system. In 6 of 37 births monitored, recordings indicated discrepancy between the actual heart rate and that estimated in the Apgar scoring system.

Asphyxia Neonatorum↗