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Biomedical subjects

E Gur

Publications and source records attributed to E Gur.

At least 19 recordsLinked to original sources
PubMed2001

Functional effects of corticosterone on 5-HT(1A) and 5-HT(1B) receptor activity in rat brain: in vivo microdialysis studies.

Glucocorticoid hormones are known to be elevated in depression, and to interact with serotonin 5-HT(1A) receptors at both the presynaptic and postsynaptic levels. Since one of the presumed mechanisms of action of antidepressant drugs is induction of changes in sensitivity of 5-HT(1A) and also 5-HT(1B) receptors, the effects of repeated administration of corticosterone (50 mg/kg s.c. b.i.d. for 10 days) on activities of these receptors were determined using in vivo microdialysis in freely moving rats. Presynaptic 5-HT(1A) receptor activity, as measured by the effect of a challenge dose (0.2 mg/kg s.c.) of the 5-HT(1A) agonist 8-hydroxy-2 (di-n-propylamino) tetralin (8-OH-DPAT) to reduce 5-HT levels in the hypothalamus, was not affected by corticosterone administration. Presynaptic 5-HT(1B) receptor activity, as measured by the effect of the 5-HT(1B) receptor antagonist (N-[4-methoxy-3-(4-methyl-1-piperizinyl)phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazole-3-yl)[1,1'-biphenyl]-carboxamide (GR 127935) (5 mg/kg s.c.) to increase 5-HT levels, was increased in hypothalamus but not hippocampus of corticosterone-treated rats. Postsynaptic 5-HT(1A) receptor activity, as measured by the effect of 8-OH-DPAT to increase cyclic AMP levels in the hippocampus, was not affected by corticosterone administration. The decrease in presynaptic 5-HT(1B) receptor activity after chronic administration of antidepressant drugs complements the increases in 5-HT(1B) receptor number observed in animal models of depression.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Walk-through injuries: glass door facial injuries.

During 1998, 13 patients were treated in the Tel-Aviv Sourasky Medical Center for complex facial soft-tissue injuries caused by passing through large, clear glass doors. All epidemiological details were gathered and analyzed. Of 1,100 soft-tissue facial injury admissions in 1 year, 13 patients had a substantial soft-tissue facial injury after passing through a glass barrier. Nine were injured during leisure time activity, five in a shopping mall, and four in their residence. Interestingly, the authors found a common pattern of facial injuries in all patients. It consisted of large, irregular, composite skin and soft-tissue flaps as well as large, tom, irregular skin lacerations. The nose was injured predominantly, and the injury was particularly complex. Their recommended management of these injuries is a thorough and careful evaluation of flap viability. Surgical management of avulsed, viable flaps includes margin debridement and repositioning. If the flap is narrow enough, it can be debrided and the margins adapted primarily. If viability of part of the flap is in doubt, that part should be debrided and used as a composite graft. When this graft dies, a full-thickness graft is taken from another facial site. The cosmesis of such a graft is better than using the debrided, thin segment as a skin graft that is too thin. The authors emphasize that there is a need to encourage authorities to reinforce regulations relating to injury prevention from architectural glass. The first is to use special glazing, either tempered glass, laminated glass, or both. The other method of improving safety is by indicating glass using decorations or warning stickers, or by making it partly translucent. Unless these regulations are obeyed, fatal or complex trauma may occur.

Adult↗
PubMed2001

Optical implementation of second-order nonlinear Volterra operators with use of triple correlation.

Following the Volterra theorem, every nonlinear operator can be implemented with a sum of integrals applied over the input. The second-order Volterra operator that describes many useful systems can be related to a single integral that is a projection of an operation called the triple correlation. This operation may be easily implemented optically and thus be incorporated into fast real-time nonlinear control systems. We present a theoretical investigation of the relation existing between the Volterra operators and the triple correlation as well as an experimental demonstration that validates the theory.

Journal Article↗
PubMed2001

Surgical treatment results in scaphoid nonunion.

Fracture of the scaphoid is the most common fracture in the wrist. We retrospectively reviewed 42 cases of established nonunion of the scaphoid that had been treated by four methods: with two Kirschner wires (K wires) and pronator quadratus pedicled bone graft in 5 patients; AO cannulated screw and graft in 8 patients; Herbert screw and graft in 19 patients; and two K wires and graft in 10 patients. Follow-up ranged from 1 to 5 years (between January 1995 and January 2000). Radiographs and computed tomography (CT) scans were analyzed for confirmation of osseous union. The average period of clinical and radiologic union was 13.2 weeks (range, 10 to 33 weeks). There was a significant improvement in the grasping power, radiologic healing, clinical satisfaction, and pain relief in the patients who had operation.

Adolescent↗
PubMed2000

Chronic repetitive transcranial magnetic stimulation induces subsensitivity of presynaptic serotonergic autoreceptor activity in rat brain.

Repetitive transcranial magnetic stimulation (rTMS) is a novel procedure which has proven effective in the treatment of major depression. We administered rTMS chronically to rats in order to determine whether this procedure affected serotonergic neurotransmission in the prefrontal cortex. Basal 5-HT levels, and the effects of challenges with the 5-HT1A receptor agonist 8-OH-DPAT and the 5-HT1B antagonist GR 127935 on 5-HT levels were determined using in vivo microdialysis. Rats which had undergone chronic rTMS showed reduced responses to both challenges, indicating subsensitivity of both the presynaptic 5-HT1A autoreceptors situated somatodendritically in the raphe nuclei and the 5-HT1B autoreceptors situated on nerve terminals. Since such subsensitivity has been demonstrated after other antidepressant treatments, our results indicate that these treatments and rTMS may have a common mechanism of action.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Chronic clomipramine alters presynaptic 5-HT(1B) and postsynaptic 5-HT(1A) receptor sensitivity in rat hypothalamus and hippocampus, respectively.

Clomipramine is a tricyclic antidepressant drug with a high affinity for the serotonin (5-HT) uptake site or transporter. Electrophysiological experiments have provided evidence that repeated administration of clomipramine induces an increase in the sensitivity of postsynaptic 5-HT(1A) receptors in the hippocampus. We have studied the effects of clomipramine, administered to rats at a dose of 10mg/kg/day for 28 days by osmotic minipumps, on presynaptic 5-HT(1A) and 5-HT(1B) autoreceptors in the hypothalamus, and on postsynaptic 5-HT(1A) receptors in the hippocampus, by using in vivo microdialysis to measure 5-HT and cyclic adenosine monophosphate (cAMP) levels. Postsynaptic 5-HT(1A) receptor sensitivity in the hypothalamus was determined by means of a neuroendocrine challenge procedure. Although the sensitivity of presynaptic 5-HT(1A) autoreceptors, as measured by the effect of a subcutaneous (s.c.) injection of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 0.2mg/kg or 50 microg/kg) to reduce 5-HT levels, did not change, there was a reduction in sensitivity of presynaptic 5-HT(1B) receptors, as measured by the effect of an injection of the 5-HT(1B/1D) antagonist GR 127935 (5mg/kg, s.c.) to increase 5-HT levels. This effect probably accounted for the increase in basal 5-HT levels observed in the hypothalamus after chronic clomipramine administration. Postsynaptic 5-HT(1A) receptor sensitivity in the hippocampus, measured by the effect of 8-OH-DPAT to increase cAMP levels in the dialysate, was increased after chronic clomipramine. Animals that had received daily intraperitoneal injections of 10mg/kg clomipramine for 28 days did not show a change in postsynaptic 5-HT(1A) receptor sensitivity in the hypothalamus as measured by the ability of 8-OH-DPAT (50 microg/kg, s.c.) to stimulate secretion of corticosterone. Taken together with the results of previous experiments involving the cerebral cortex, these in vivo results show that chronic clomipramine exerts effects on both pre- and postsynaptic serotonin receptors, but that these effects are highly region-specific.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Subchronic fluoxetine administration to rats: effects on 5-HT autoreceptor activity as measured by in vivo microdialysis.

Subchronic administration of fluoxetine to rats has been shown to induce subsensitivity of presynaptic 5-HT(1A) and 5-HT(1B) autoreceptors, and also postsynaptic 5-HT(1A) receptors in the hypothalamus. We investigated the effects of administration of fluoxetine (10 mg/kg i.p.) to rats for 6 days on presynaptic 5-HT(1A) receptor activity in the hypothalamus, postsynaptic 5-HT(1A) receptor activity in the hippocampus, and presynaptic 5-HT(1B) autoreceptor activity in both areas, using in vivo microdialysis. The effect of the 5-HT(1B/1D) antagonist (N-[4-methoxy-3-(4-methyl-1-piperizinyl)phenyl]-2'-methyl-4'-(5- methyl-1,2,4-oxadiazole-3-yl)[1,1'-biphenyl]-carboxamide (GR 127935) (5 mg/kg s.c.) to elevate 5-hydroxytryptamine (5-HT) levels was reduced in hippocampus but not hypothalamus of fluoxetine-treated rats. Fluoxetine did not alter either presynaptic 5-HT(1A) autoreceptor activity, as measured by the effect of injection of 8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT) (0.2 mg/kg or 50 microg/kg s.c.) on 5-HT levels in the hypothalamus, or postsynaptic 5-HT(1A) receptor activity, as measured by the effect of 8-OH-DPAT (0.2 mg/kg s.c.) on cyclic AMP accumulation, in the hippocampus.

Animals↗
PubMed2000

Control of methionine biosynthesis in Escherichia coli by proteolysis.

Most bacterial proteins are stable, with half-lives considerably longer than the generation time. In Escherichia coli, the few exceptions are unstable regulatory proteins. The results presented here indicate that the first enzyme in methionine biosynthesis - homoserine trans-succinylase (HTS) - is unstable and subject to energy-dependent proteolysis. The enzyme is stable in triple mutants defective in Lon-, HslVU- and ClpP-dependent proteases. The instability of the protein is determined by the amino-terminal part of the protein, and its removal or substitution by the N-terminal part of beta-galactosidase confers stability. The effect of the amino-terminal segment is not caused by the N-end rule, as substitution of the first amino acid does not affect the stability of the protein. HTS is the first biosynthetic E. coli enzyme shown to have a short half-life and may represent a group of biosynthetic enzymes whose expression is controlled by proteolysis. Alternatively, the proteolytic processing of HTS may be unique to this enzyme and could reflect its central role in regulating bacterial growth, especially at elevated temperatures.

Acyltransferases↗
PubMed2000

Abdominal recovery after laparotomy and omental transposition into a grossly contaminated median sternotomy wound.

Grossly contaminated median sternotomy wounds are frequently treated with transposed omental flaps. A laparotomy adjacent to such an infected wound carries the risk of peritonitis. It has been suggested that this risk may increase when the omentum, which has anti-infective properties, is removed from the abdominal cavity and is transposed to the chest. The authors evaluated abdominal recovery after laparotomy and omental transposition into an adjacent, grossly contaminated median sternotomy wound. The study group included 15 patients who had sternal wound reconstruction with an omental flap between 1990 and 1998. All patients underwent median sternotomy reconstruction according to a "two-compartment" operative sequence protocol, which included division of the surgical field into an upper (thoracic) contaminated zone and a lower (abdominal) clean zone. The control group was comprised of 15 patients who underwent elective laparotomy for splenectomy during the same time period. The effect of the surgical procedure on the abdomen was compared between the two groups. The timing of the reappearance of peristalsis and regular bowel function, and the incidence of bowel obstruction and postoperative peritonitis were similar in the two groups. The findings indicate that laparotomy and omental transposition in the presence of a grossly contaminated median sternotomy wound is a safe procedure, and is associated with a low rate of abdominal complications.

Aged↗
PubMed2000

The free vascularized flap and the flap plate options: comparative results of reconstruction of lateral mandibular defects.

OBJECTIVES/HYPOTHESIS: Reconstruction of the mandible and oral cavity after segmental resection is a challenging surgical problem. Although osteocutaneous free flaps are generally accepted to be optimal for reconstruction of anterior defects, the need for bony reconstruction for a pure lateral mandibular defect remains controversial. STUDY DESIGN: A retrospective study. METHODS: A retrospective comparative study of short- and long-term outcomes of three different reconstruction techniques for lateral defects was performed. In total, 57 patients were included, of whom 27 had a plate and pedicled pectoralis major myocutaneous flap (PMMF group), 16 had a plate and free radial forearm flap (FRFF group), and 14 had an osteocutaneous free flap. Functionality, flap failure, and complications were scored. RESULTS: Plates had to be removed in 7 of the 27 patients in the PMMF group and 2 of the 16 in the FRFF group; none of the 14 osteocutaneous free flaps failed. The difference was of borderline statistical significance (P = .055). Longterm functional outcome revealed no statistically significant difference in oral deglutition (P = .76) or in facial contour (P = .36). Oral continence was significantly better in patients in the FRFF group (88%) as compared with the PMMF group (52%) or the osteocutaneous free flap group (43%) (P = .02). On the other hand, the results for speech favored the osteocutaneous free flap group; 13 of 14 patients (92.9%) had a normal score compared with 12 of 16 patients (75%) in the FRFF group and 17 of 27 (63%) in the PMMF group. However, this represented a borderline statistically significant result (P = .06). CONCLUSIONS: For lateral mandibular defects, the osteocutaneous free flap is reliable and durable in the long term. However, in a selected group of patients either of the two flap-plate options is a viable reconstructive option.

Carcinoma, Squamous Cell↗
PubMed2000

The vascularized pig fibula bone flap model: effect of segmental osteotomies and internal fixation on blood flow.

The free fibular flap is the flap of choice for reconstruction of complex mandibular defects, although two or more osteotomies may be required to recreate the normal mandibular contour. The effect of these surgical manipulations on the fibula has not been adequately investigated. This study was designed to study the effect of multiple segmental osteotomies and internal fixation techniques on blood flow in the vascularized pig fibula bone flap model. The hindlimbs of 15 Yorkshire pigs were randomized into 1 of 5 groups (n = 6 fibulae per group) consisting of: (1) a nonoperated, in situ fibula; (2) an elevated fibula flap; (3) an elevated fibula flap with two segmental osteotomies; (4) an elevated fibula with two segmental closing osteotomies rigidly fixed with 2-mm miniplates; (5) an elevated fibula with two segmental closing osteotomies rigidly fixed with 2-mm lag screws. Total and gradient blood flow was measured in the bone and soft-tissue components of these flaps using the 15-microm radioactive microsphere technique. The creation of two segmental osteotomies in the vascularized pig fibula bone flap model resulted in a significant decrease (p<0.05) in the gradient blood flow in the segment of bone distal to the second osteotomy. Application of miniplates or lag screws across closing osteotomies resulted in a significant decrease (p<0.05) in total and gradient blood flow to the bone component of the fibulae, as compared with the elevated and osteotomized fibulae groups. An increase in blood flow suggesting a hyperemic response was noted in the bone and soft tissue in the elevated and osteotomized flap groups as compared with the in situ, nonoperated controls. This study established the validity of the pig fibula as a suitable model for investigating the pathophysiology of blood flow changes in the face of standard surgical maneuvers necessary for the restoration of mandibular form and function. The results demonstrated that the creation of multiple segmental osteotomies and the application of internal fixation significantly decreases (p<0.05) blood flow to the distal portion of the flap. The effects of segmental osteotomies and internal fixation on healing and growth of the pig fibula bone flap model are investigated in a separate study.

Animals↗
PubMed2000

Complex facial nevi: a surgical algorithm.

Sixty-six children with large congenital nevi of the face were surgically managed in our center during the last 8 years. All patients with a lesion that posed a reconstructive challenge were included in the study. None could be effectively dealt with by excision and simple primary closure. To simplify description and evaluation, the patients were divided into three groups. Group I had 15 patients with relatively small lesions (1- to 3-cm maximal diameter) that were confined to one aesthetic unit of the face and could be reconstructed in one stage. Reconstruction was usually achieved by using local skin flaps or with full-thickness skin grafting. Group II had 28 patients with medium-sized lesions (3- to 12-cm maximal diameter) that involved one or two aesthetic units and required not more than two stages for reconstruction. These patients usually needed either serial excisions and/or skin grafting or a two-stage tissue expansion procedure (insertion of tissue expanders and reconstruction). Group III had 23 patients with very large lesions (over 12 cm in maximal diameter), some covering half of the face and thus involving several aesthetic units and requiring multiple stages for reconstruction. These patients required a combination of tissue expansion procedures, large faciocervical and scalp/forehead skin flaps, full-thickness skin grafting, and serial excisions for reconstruction. The anatomic distribution of the lesions over the various aesthetic units is described, as are the reconstructive techniques with advantages and disadvantages of each, reflecting on outcome. The approach to the larger complex lesions is detailed. Based on our experience, a reconstructive algorithm is proposed.

Adolescent↗
PubMed2000

Use of sunscreen is linked with elevated naevi counts in Israeli school children and adolescents.

Epidemiological evidence indicates that a fair complexion and exposure to solar radiation in early years contribute to the proliferation of naevi and subsequent melanoma risk. To determine whether protection from sunlight is associated with lower naevi counts, we examined the prevalence and risk factors of naevi in a sample of Israeli school pupils. Whole body counts of naevi were recorded in 974 out of 1312 (74.2%) recruited pupils (7 and 12 year olds) from Ramat-Gan and Jerusalem. Host characteristics and habits of sun exposure were obtained using questionnaires. In each age group and geographic area, the mean whole body naevi counts, adjusted for confounders, were higher among males, pupils of European-American descent, and those susceptible to sunburn. The contributions to naevi risk of fair skin colour and frequent recreational sun exposure were higher among 7 year olds. Regular sunscreen use contributed to the naevi risk for both age strata in Ramat-Gan (at age 7, rate ratio [RR] = 1.7, 95% confidence interval [CI] = 1.3-2.2; at age 12, RR = 1.5, 95% CI = 1.1-2.1). Among the younger age group in Ramat-Gan, even seldom compared with no use of sunscreen was associated with higher naevi counts (RR= 1.5, 95% CI = 1.2-2.0). Similar patterns were noted with the pupils from Jerusalem. In conclusion, the elevated naevi count with increased sunscreen use indicates that sunscreens apparently do not modify the genetic predisposition to naevi proliferation. For better protection of children and adolescents, including those who use sunscreens, from the naevogenic effect of solar radiation, they should be encouraged to limit their exposure and wear protective clothing when in the sun.

Adolescent↗
PubMed2000

The diamond vermilion flap--a new technique for vermilion augmentation in cleft lip repair.

OBJECTIVE: In most cleft lips patients, the vermilion on the medial aspect of the repair is deficient in height. Not many surgeons have dealt with ways to augment the height of the vermilion at this location. In the unilateral cleft lip, the repair may include the insertion of a small triangular vermilion flap from the cleft side into an incision made for it in the muco-vermilion junction of the noncleft side. We have developed a new technique to further augment the vermilion in incomplete cleft lip patients. METHOD: Vermilion remnants may be present in these patients on the scar tissue between the margins of the cleft. A diamond-shaped vermilion flap based on its attachments to the orbicularis oris muscle may be transposed into the noncleft side to an incision made caudal and parallel to the muco-vermilion border. Then the triangular vermilion flap may be inserted just distal to the island flap. Using this method, the vermilion is augmented and the muco-vermilion line parallels more the white skin roll.

Cleft Lip↗
PubMed2000

Bone density values in healthy Turkish infants.

OBJECTIVE: To determine values of bone density of Turkish infants under one year of age. DESIGN: Cross sectional. METHODS: This study included 1, 2, 4, 6, 9 and 12 months old 164 male and female healthy infants who were evaluated by dual energy X-ray absorbtiometry. RESULTS: The values for each age were computed. There was no significant difference between boys and girls. A significant relationship was found between bone mineral density, bone mineral content, total body calcium and calcium/body surface, and age, height, body weight, head circumference and body surface area. Multiple regression analysis showed that body mineral density was affected by weight, height, head circumference and body mass index. Body mineral content and total calcium content were affected by weight and height. CONCLUSION: The results will serve as reference values for healthy 1-12 months old Turkish infants.

Absorptiometry, Photon↗
PubMed1999

Venlafaxine: acute and chronic effects on 5-hydroxytryptamine levels in rat brain in vivo.

Venlafaxine is a dual serotonin (5-hydroxytryptamine, 5-HT) and noradrenaline uptake inhibitor which has been claimed to have an onset of antidepressant action which is faster than for other comparable drugs. The effects of venlafaxine on brain 5-HT levels in vivo have not yet been examined. Acute administration of venlafaxine to rats by i.p. injection resulted in dose-dependent increases in cortical and hippocampal 5-HT levels, as measured by in vivo microdialysis, over the range 5-20 mg/kg. The effect of venlafaxine (10 mg/kg i.p.) was potentiated by prior administration of pindolol (10 mg/kg s.c.) in hippocampus but not in frontal cortex. Daily administration of venlafaxine (5 mg/kg i.p.) for 4 weeks did not change basal 5-HT levels in either brain area. The effect of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 0.2 mg/kg s.c.) to reduce 5-HT levels was unaffected by chronic venlafaxine at this dose, indicating that there was no change in sensitivity of presynaptic 5-HT1A autoreceptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗