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Biomedical subjects

D Segal

Publications and source records attributed to D Segal.

At least 19 recordsLinked to original sources
PubMed1996

Alkynyl phosphates are potent inhibitors of serine enzyme.

Propynyl, hexynyl and t-butylethynyl diethyl phosphates were found to be very powerful covalent inhibitors of serine enzymes. Esterases were inhibited with second-order rate constants of 10(7)-10(8) m(-1) min(-1). Most proteases were inhibited with a rate constant of 10(4)-10(5) M(-1) min(-1). By inhibiting chymotrypsin with (3-14C)-1-propynyl diethyl phosphate, it was established that inhibition was caused by binding of the phosphate group to the enzyme active site.

Aldehyde Dehydrogenase↗
PubMed1996

Genetic transformation of Drosophila cells in culture by P element-mediated transposition.

We report that cells of a Drosophila embryonic cell line (Kc167 cells) can be readily and stably transformed by transposition of P elements from exogenous DNA. Cells are transfected with plasmids carrying methotrexate- or alpha-amanitin-resistance markers expressed from constitutive promoters and co-transfected with a gene encoding a somatically active transposase. Transient expression of the transposase leads to efficient production of transformed, resistant cells. We describe conditions under which most resistant clones are healthy and harbor a small number (1-50) of transposons and few (< or = 5%) retain plasmid sequences derived from illegitimate recombination. Using conditions like these it should prove possible to construct enhancer trap and/or gene libraries using Drosophila cells.

Amanitins↗
PubMed1996

Osteoarthritis, the hazard of living longer: arthroscopy vs. conservative treatment.

The lengthening of the average life span has led to an increase in degenerative diseases, among them osteoarthritis. Arthroscopy, which has been used extensively to decrease pain and inflammation and increase the range of motion, has recently been challenged as the treatment of choice. Several studies have found that joint lavage, which is a less costly procedure, provides better solutions to joint disorders. In Israel, where resources for health care are limited, physicians must also be guided by cost-benefit and cost-effectiveness. Since there is limited benefit to be gained from arthroscopy in cases where there is no mechanical damage to the knee, we suggest that nonsurgical, conservative methods be employed in treating the majority of cases of osteoarthritis.

Aged↗
PubMed1996

Treatment of high-energy proximal tibial fractures using the Monticelli-Spinelli external fixator: a preliminary report.

Between 1990 to 1993, 21 patients with tibial plateau or proximal tibial fractures resulting from high-energy trauma were treated with the Monticelli-Spinelli external fixator. There were 13 men and 8 women (mean age, 45.2 years; range, 26 to 78). There were a total of 5 type A, 2 type B, and 14 type C fractures, using the Arbeitsgemeinschaft Fur Osteosynthesefragen (AO) classification system. Immediate postoperative reductions were good or excellent, according to strict radiographic criteria, in 16 of 21 patients. All patients obtained at least 90 degrees of knee flexion, and only one patient lost more than 5 degrees of full extension. Complications included seven superficial pin-tract infections and one deep vein thrombosis with resultant pulmonary embolism. Nineteen patients were available for follow-up (mean, 14 months). Clinically, 13 patients had satisfactory results where good or excellent radiographic reductions were maintained, knee extension was within 5 degrees of full, flexion was > or = 90 degrees, with < or = 5 degrees valgus/varus angulation. Six patients had unsatisfactory results, not meeting the above criteria. The Monticelli-Spinelli external fixator is a much-needed tool in the treatment of high-energy tibial plateau fractures that are not amenable to more extensive surgical procedures because of the associated soft-tissue injuries.

Adult↗
PubMed1996

Brain perfusion imaging during preoperative temporary balloon occlusion of the internal carotid artery.

UNLABELLED: The main objective of this study was to assess whether 99mTc-HMPAO brain SPECT imaging can identify patients at high risk of developing an infarct following permanent carotid occlusion in the course of brain surgery. METHODS: Test balloon occlusion of the internal carotid artery was performed in 44 patients with a variety of head and neck tumors or aneurysms. Technetium-99m-HMPAO was injected intravenously while the balloon was initiated and a SPECT study was obtained 30 min later. Follow-up CT scans were obtained routinely for all patients at 2 wk and 1 mo following surgery, or earlier when necessary. Thirty patients and five normal volunteers had semiquantitative analysis of cerebral perfusion. RESULTS: Twenty-six patients demonstrated ipsilateral perfusion abnormalities during trial occlusion. Eight patients in this group underwent bypass grafting prior to sacrifice of the artery: two resulting in infarcts. Eighteen patients had symmetric cerebral perfusion during occlusion and four of these patients underwent permanent therapeutic carotid occlusion; three patients had subsequent infarcts and the fourth patient had an impending stroke. CONCLUSION: Patients with symmetric cerebral perfusion measured by 99mTc-HMPAO SPECT may still have a high long-term complication rate following carotid sacrifice. The scan findings in these patients were not predictive of the outcome. Patients with asymmetric cerebral perfusion had alternative therapeutic approach to carotid sacrifice and most of them had good surgical outcomes.

Brain↗
PubMed1996

[Immediate posterior stabilization of pelvic fractures using threaded compression rods].

Operative management of pelvic ring disruptions remains a challenge for the orthopedist. Surgical stabilization of an unstable pelvic ring not only involves urgent control of shock, but also protects soft tissues and enables the patient to ambulate earlier and to be comfortable when resting. Appropriate management of pelvic ring injuries requires understanding the anatomy and biomechanics of the pelvis and the mechanism of injury. The choice of posterior stabilization depends on the type of fracture. In this study we evaluated posterior tansiliac fixation using threaded compression rods (sacral bars), 1 of the techniques for treating pelvic instability with disruption of the posterior osseous - ligamentous complex. We used this method during 1987 - 1991 on 17 multitrauma patients with unstable pelvic injuries. We also conducted a long-term follow-up of more than 2 years. The 2 type C3 patients required revision of the posterior fixation, due to loss of stability and recurrence of dislocation of the sacroiliac joint. This seems to support the view that posterior sacral bar fixation is not suitable for bilateral rotational and vertical instability, and that it should be limited to certain posterior injury patterns, including lateral compression injuries and unilateral vertical instability when the contralateral hemipelvis is stable. It is important therefore, that the trauma surgeon be familiar with more than 1 technique of stabilization. Our study indicated that fixation with sacral bars is still an easy, safe and useful method for treating posterior pelvic instability, even though anatomical reduction of the sacroiliac joint is difficult. It should be one of the techniques with which the orthopedic trauma surgeon is acquainted and is ready to use when necessary.

Follow-Up Studies↗
PubMed1995

Genetic and molecular studies of apterous: a gene implicated in the juvenile hormone system of Drosophila.

The apterous (ap) gene in Drosophila melanogaster encodes a homeodomain transcription factor. It is required for the development of the wings and of a subset of embryonic muscles. The gene has been implicated in the juvenile hormone (JH) system because mutations in ap lead to JH deficiency, and are associated with defective histolysis of the larval fat body, arrested vitellogenesis, sterility, and aberrant sexual behavior, all of which are dependent on JH. We describe here the use of hemizygotes and germ-line clones, of X-ray- and hybrid dysgenesis-induced lethal ap alleles to determine the primary role of the gene during development. We find that ap lethality is polyphasic, but occurs primarily at the larval and pupal stages. The lethal phenotype is not associated with any overt morphological abnormality, suggesting that death occurs from a systemic malfunction. Strong interallelic complementation for the wing phenotype was found between some ap mutations induced by X-rays or by hybrid-dysgenesis. By Northern blot analysis, we demonstrate an increase in ap expression in pupae and adults as compared to embryos and larvae, suggesting that it is developmentally regulated. Finally, primer extension is used to determine the transcription start site of the gene.

Alleles↗
PubMed1995

Genetic variation for resistance to chlorpyrifos in Drosophila melanogaster (Diptera: Drosophilidae) infesting grapes in Israel.

Five species of drosophilid flies were observed breeding in grapes growing in Israel; of these, 2 species, Drosophila melanogaster (Meigen) and D. simulans Sturtevant, are major pests. Natural populations of both species were sampled and tested for resistance to chlorpyrifos; the 2 more intensively sampled populations were D. melanogaster in commercial vineyards. One vineyard had been treated repeatedly with chlorpyrifos to control this secondary pest species; the other had never been treated with an organophosphorus compound. The LC50 to chlorpyrifos of a genetically heterogeneous line of D. melanogaster from the exposed population (Be'er Tuvia) was 99 ng/cm2, and the LC50 of a corresponding line from the unexposed population (Sde Eliahu) was 52 ng/cm2; the wild-caught lines were much more resistant than a laboratory strain, Canton-S, whose LC50 was 0.25 ng/cm2. Genetic variance for resistance existed in both natural populations but realized heritability did not differ significantly between the populations. In crosses between a highly resistant strain and several sensitive laboratory strains of D. melanogaster, resistance was dominant. A resistance factor was mapped to a locus on chromosome 2 (approximately 2-72).

Animals↗
PubMed1995

Avid uptake of technetium-99m-HMPAO by an intracranial plasmacytoma during carotid balloon test occlusion.

A 56-yr-old woman was evaluated for removal of a tumor at the base of the skull. A test to determine the risk of carotid artery sacrifice was performed prior to surgery using carotid balloon occlusion of the left internal carotid artery and 99mTc-HMPAO perfusion scintigraphy during the occlusion. An unusual intense focus of increased uptake was seen at the site of the primary tumor in the left cavernous sinus. The tumor, found to be plasmacytoma at surgery, demonstrated only mild washout from 30 min to 2 hr after administration of 99mTc-HMPAO, with a tumor-to-cerebellum ratio of 1.6 and 1.5, respectively, and a tumor-to-contralateral cranial ratio of 2.5 and 2.4, respectively. Intracranial plasmacytoma shows good response to radiation therapy, and the differentiation of this tumor from other neoplasms is pertinent to the mode of treatment and surgical approach. Technetium-99m-HMPAO SPECT imaging may be a useful tool in distinguishing these tumors from other neoplasms at the base of the skull.

Brain Neoplasms↗
PubMed1995

Tibial implant mineralization in rats is inversely related to serum osteogenic capacity.

In this study, the correlation between the mineralization of healing bone defects and the osteogenic capacity of the serum was tested in rats. The purpose of the study was to test the hypothesis that during callus formation, some serum factors are consumed. The bone defects in the tibia contained two different implant types, and all sustained juxta-implant fractures. One implant type was the coral Porites and the other was its recrystallized version (Interpore-200), which exhibit different mineralization rates during fracture healing. Use of these two implant types permitted generation of an expanded mineralization spectrum suitable for regression analysis. Mineralization was assessed by measuring the mineral content change (MCC) using dual-energy X-ray absorptiometry. Osteogenic capacity of sera of the implanted rats was assessed by its ability to increase specific alkaline phosphatase (ALP) activity in stromal cell cultures. The MCC was followed for 5 weeks in the Porites and Interpore-200 implants, and it was found that the MCC in Interpore-200 implants exceeded that of the Porites implants. Thus, the two implant types generated a wide mineralization spectrum. Induction of ALP in stromal cell culture was lower for sera derived from rats implanted with Interpore-200 than for sera derived from rats implanted with Porites. Two weeks after implantation, the change in serum ALP induction correlated inversely with the MCC of bone defects. This indicates that during callus formation, the mineralization rate is reciprocally related to the serum osteogenic capacity. The decreased serum osteogenic capacity may be interpreted by the hypothesis that callus formation consumes certain serum osteogenic factors.

Alkaline Phosphatase↗
PubMed1995

Treatment of intercondylar and supracondylar distal femur fractures using the GSH supracondylar nail.

From April 1990 to August 1994, the GSH supracondylar intramedullary nail (Smith & Nephew/Richards, Memphis, Tennessee) was used to treat 23 supracondylar femur fractures in 22 patients. Nineteen of the 23 fractures were highly comminuted and intra-articular. Fifteen patients with 16 fractures were followed up to healing or declaration of nonunion for an average of 10 months. All fractures were treated with direct reduction through a median parapatellar incision. Fixation of the intercondylar fractures was with 6.5-mm cannulated screws, and the GSH nail was then inserted between the screws to secure the articular segment to the shaft. Fifteen of the 16 fractures healed (94%) with excellent and good results at an average of 3.3 months. Initial postoperative fracture reduction was maintained in all patients until union, as shown by follow-up radiographs. Thirteen of the 16 patients were treated with immediate continuous passive motion of the knee. Average knee range-of-motion was 109 degrees. Complications included 1 nonunion, 1 delayed union, 1 hardware failure secondary to premature full weight-bearing, and 1 patient with impingement of the nail in the intercondylar notch. This impingement resolved with removal of the nail after fracture healing. The GSH supracondylar intramedullary nail is an excellent alternative for the treatment of supracondylar and intercondylar femur fractures.

Adult↗
PubMed1995

Is carotid artery reconstruction mandatory?

The risks and benefits of carotid artery sacrifice should be carefully weighed in every patient individually. The balloon test occlusion with CBF measurement is an important part of the decision process and can guide the surgeon regarding the treatment options most suitable in a particular situation. Although a patient may tolerate temporary occlusion with no CBF disturbance, there is a small risk of stroke on carotid sacrifice. Once the patient suffers a stroke, there is little that can be done. Therefore, if carotid sacrifice is deemed necessary in a patient, some type of revascularization should be considered. Revascularization should be performed with meticulous attention to detail, because it is not without risk. Intraoperative neurophysiologic monitoring and intraoperative arteriography are important adjuncts in such operations.

Adolescent↗
PubMed1994

Marrow stromal cell commitment to mineralization under the effect of a prolyl hydroxylase inhibitor.

Mitochondrial response to the effect of a hydroxylase (PH) inhibitor was tested in marrow stromal cells during stimulation of osteoprogenitor cell (OPC) differentiation. The rationale for this was to explore pathways of regulatory interactions between procollagen synthesis and mitochondrial respiration that could be linked to the commitment of OPCs to mineralization. Stimulated OPCs exposed to the PH inhibitor cis-hydroxyproline (cis-HP), compared to the noninhibiting isomer trans-HP, for 11 days showed a dose-dependent decrease in cell proliferation, the surviving cells showed increased alkaline phosphatase activity. Trans-HP did not influence the cis-HP effect on ALP and on proliferation arrest. Short time exposures, 2-3 days, to cis-HP at different periods suggested that Days 0-3 and 3-5 were critical for the commitment to Day 21 mineralization of OPCs. On Days 0-3 cells were most sensitive to cis-HP, since on Day 11, 8 days after removal of cis-HP, they were too scarce to be counted by the staining method. However, the presence of 5.0 mM cis-HP in the cultures during Days 3-5 has induced on Day 21 close to 24-fold more mineralization/cell than controls, compared to the trans-HP effect, which was only close to 3-fold. The presence of cis-HP in the cultures on Days 0-3 has augmented the mitochondrial Day 3 retention of rhodamine 123 (Rho) in the stromal cells, relative to controls, compared to the presence of trans-HP. However, the presence of cis-HP during Days 3-5 or 3-6 resulted in lower Day 5 Rho retention, relative to controls, which was not significantly different from the retention that resulted from trans-HP. Since Rho retention is related to the final result of aerobic respiration level, these results are interpreted as a cis-HP inhibitory effect on procollagen peptidyl-proline hydroxylation, which may in turn release oxygen surpluses, to be available for mitochondrial consumption. The fall in Rho retention responses to cis-HP between Days 0-3 and 3-5 is suggesting either abrupt decrease in proline hydroxylation or poor mitochondrial sensitivity to oxygen in Day 3-5 cultures.

Alkaline Phosphatase↗
PubMed1994

Hypnosis and the dream hidden observer: primary process and demand characteristics.

In Study 1, virtuoso (n = 13; passed more than 10 suggestions on the Harvard Group Scale of Hypnotic Susceptibility, Form A [HGSHS:A] and Stanford Hypnotic Susceptibility Scale, Form C), high hypnotizable (n = 14; passed more than 8 suggestions on the HGSHS:A), and medium hypnotizable (n = 17; passed 4-8 suggestions on the HGSHS:A) Ss were administered a hypnotic dream suggestion followed by a "dream hidden observer" suggestion (i.e., access hidden part; have new thoughts and images pertinent to dream). The majority of Ss reported dreams (81.8%) and hidden observers (80%), with hidden reports being characterized by more personal content, less primary processes, and poorer recall than dream reports. Study 2 replicated major findings. Although hypnotized (n = 18) and low hypnotizable simulating Ss (n = 17) responded comparably on most measures, hypnotizable Ss' dreams contained more primary process than did simulating Ss, providing support for M. R. Nash's (1991) psychoanalytic model.

Adult↗
PubMed1994

The hidden observer, hypnotic dreams, and age regression: clinical implications.

This article summarizes data from three studies (Maré, Lynn, Kvaal, Segal, & Sivec, in press; Lynn, Maré, Kvaal, Segal, & Sivec, 1993) designed to extend research on the "hidden observer" to two phenomena of clinical relevance: hypnotic dreams and suggested age regression. Subjects received suggestions for a hypnotic dream or age regression and then received suggestions for a "hidden observer" (i.e., the subject possesses a part of the self that is aware of images and ideas that the conscious mind is unaware of) with respect to the dream or age-regression experience. Hidden reports contained more personally relevant information than the target suggestions (i.e., dream, age regression). Subjectives were also less likely to recall hidden reports. The high rate of hidden-observer responding (> 80%) was also evident in nonhypnotized simulating and relaxed subjects, although they did not exhibit as much primary process thinking in their dream reports as hypnotized subjects. Case studies of a trauma client and a forensic client are used to illustrate the clinical potential of hidden-observer suggestions.

Adult↗
PubMed1993

Prospects of using Drosophila for insect neuroendocrine research.

Classical and in vitro approaches for the analysis of the molecular components of neuroendocrine systems often disrupt their close interaction with other bodily systems, which is a crucial aspect of their function in vivo. "Genetic dissection" is an alternative, noninvasive approach which involves the systematic generation of mutations in individual genes, followed by in vivo analysis of the phenotypic effects of altering a single protein at a time avoiding extraneous disruptions. Among insects Drosophila melanogaster is the most suitable model for this approach. This paper explores the application of genetic and molecular techniques available in Drosophila for studying its neuroendocrine system with special emphasis on the production of ecdysone and juvenile hormone. Strategies are described for the generation and identification of endocrine mutations, especially those affecting hormone synthesis and regulation. Once identified by a specific mutation, a gene in Drosophila can be cloned either by chromosomal microdissection and "chromosomal walk" or by transposon tagging. Methods for molecular analysis of the structure and function of a cloned gene and of the protein it encodes are available for further study. Alternatively, a gene can be cloned using heterologous DNA probes or oligonucleotides designed according to the amino acid sequence of a protein. Genes may also be cloned via their pattern of expression (using stage- or tissue-specific cDNA libraries or through transposon-mediated "enhancer detection." Anti-sense RNA, the replacement of the gene by in vitro manipulated versions, or mutagenesis of its endogenous copies can then be used for studying its function in vivo. Information about endocrine genes in Drosophila as well as material such as cloned genes and antibodies should be useful for the analysis of endocrine systems in other insects which are not amenable to genetic manipulations. Such information should be helpful in designing novel means for pest control based on the specific intervention with endocrine systems regulating insect development and reproduction.

Animals↗
PubMed1993

Selection of malonate-resistant stromal cell-derived osteoprogenitor cells in vitro.

Bone marrow stromal cells give rise to osteoprogenitor cell (OPC) colonies, with characteristic mineralized bone nodules in vitro. During differentiation, OPCs in the culture are surrounded by heterogeneous populations of various cell lineages and by different OPC differentiation stages. In the present study, attempts were made to increase the homogeneity of OPCs in culture. The reliance on energy metabolism restricted to glycolysis, which is specific to the premineralizing skeletal cells, was tested as a selectable marker for cells in this stage. Day 12 alkaline phosphatase (ALP) and day 20-21 calcium precipitates were used as early and late OPC differentiation markers. Malonate, a competitive inhibitor of succinate dehydrogenase, was added to the OPC stimulation medium, to interfere with the Krebs cycle-dependent energy metabolism operating in most of the stromal cells. OPCs that entered the stage of energy metabolism restricted to glycolysis were expected to become malonate resistant. Malonate showed dose and time dependence, 10 mM malonate added on day 3, decreased day 12 ALP activity/well to the lowest level. Variations in time and length of exposure to malonate used during the first 12 days of differentiation showed an inverse correlation between specific ALP activity and cell yield. Malonate-treated variations of specific ALP and of cell yield indices were up to 30- to 40-fold larger than variations within day 21 calcium precipitates. Thus, calcifying cells were almost unchanged relatively to noncalcifying cells. These results indicate that malonate-resistant cells are mostly selected, rather than induced, to differentiate by malonate. The results also show that stromal derived OPCs undergo a similar biochemical stage as in chondrocytes.

Alkaline Phosphatase↗