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Biomedical subjects

D Segal

Publications and source records attributed to D Segal.

At least 109 records · Page 6Linked to original sources
PubMed1990

Unstable intertrochanteric/subtrochanteric fractures of the femur.

The unstable intertrochanteric/subtrochanteric fracture, as identified by the modified Müller classification, should be considered a separate entity with its own problems. It can be highly unstable; none of the orthopedic appliances has been designed with this fracture in mind. Compression screws yield better results than Enders rods in these fractures. However, eight patients (16%) in this study who were treated with a compression screw did have a complication. Thus, further studies need to be done to develop other orthopedic appliances for these unstable fractures. Enders rods and compression screws were used to treat 72 unstable intertrochanteric/subtrochanteric fractures. The type of surgical procedure was determined by the surgeon. Anesthesia time and blood loss were significantly lower in the group treated with the Enders nail. Intraoperative and postoperative complications of the Enders group were reported in four (20%) and eight patients (32%), respectively, as compared to zero and eight patients (16%) in the compression screw group. Postoperative time to ambulation, knee pain, and reoperation rate were significantly higher in those treated with the Enders nail. Fracture reduction and ideal device position were acceptable in only 16 patients (64%) and four patients (16%) of the Enders group, respectively, compared with 46 patients (98%) and 40 patients (86%) in the compression screw group.

Aged↗
PubMed1990

Ender rods versus external fixation in the treatment of open tibial fractures.

This is a retrospective nonrandomized study of 66 open tibial fracture patients that compares comparable population treated at one trauma center. The fractures were treated with either Ender rods or external fixation. Of these, 29 fractures were eliminated from the study due to incomparable variables. Thus, the study group consisted of a total of 37 tibial fractures: 20 treated by Ender rods and 17 treated by external fixation. Open tibial fractures treated with Ender rods had a significantly lower number of complications than those treated with external fixation. The group treated with Ender rods also had a significantly lower number of surgical procedures per patient in Grades I and II open tibial fractures. There were no statistical differences regarding weeks to union or hospital days. Ender rods are superior to external fixation removed early in the treatment of Gustilo's Grades I, II, and IIIA open fractures with either stable or unstable fracture configuration (Orthopaedic Trauma Association Grades IA-IC, IIA-IID, and IIIA-IIIC). Perhaps future study will allow sufficient numbers to determine whether Ender rods can be used in Grades IIIB and IIIC open tibial fractures, but there are no data at this time to support this conclusion.

Adult↗
PubMed1989

The interaction of alkynyl carboxylates with serine enzymes. A potent new class of serine enzyme inhibitors.

The recently reported alkynyl esters, propynyl benzoate and propynyl p-methoxybenzoate, were found to interact with a variety of serine enzymes. alpha-Chymotrypsin was inhibited very rapidly by an equivalent amount of the esters. Trypsin, elastase and pronase were also inhibited by the esters. On the other hand, liver esterase started to hydrolyze the alkynyl esters rapidly, but the enzyme became inhibited during the course of reaction. The inhibited enzymes exhibited slow reactivation which could be considerably enhanced by hydroxylamine.

Benzoates↗
PubMed1989

Fractures of the body of the tarsal navicular bone: case reports and literature review.

Four patients sustaining tarsal navicular body fractures are presented. Analysis based on these cases and on 36 patients suffering from identical fractures reported in the literature led to a new mechanical assumption: the axial compression on the foot, as a result of falling from height, causes impaction of the talus into the body of the navicular bone. The clinical followup results reported are usually disappointing. Favorable results are obtained in a vertical two-part fracture, by an open reduction and internal fixation of the tarsal navicular body fracture. In highly comminuted fractures, talo-navicular-cuneiform arthrodesis can be carried out.

Adolescent↗
PubMed1989

Crush injuries of the foot with compartment syndrome: immediate one-stage management.

Severe crush injuries with compartment syndrome were treated in five patients by an immediate one-stage procedure. This procedure included the assessment of skin flap viability with accurate debridement of devascularized tissues. It was performed according to the split-thickness skin excision technique. Compartment pressures were measured and the fasciotomies were performed through open wounds or separate medial and lateral incisions. The medial incision was extended to release the tarsal tunnel. Fractures were reduced and internally fixed and exposed bones were covered with locally transposed muscles. Skin grafts, taken earlier for the skin viability assessment, were meshed and applied to replace skin loss. All wounds and fractures healed uneventfully with no major functional loss. In multiple trauma, the physician should maintain a high index of suspicion for early diagnosis and treatment of severe foot injuries. Early treatment leads to more desirable results, shorter hospitalization, and faster rehabilitation.

Adult↗
PubMed1989

Concomitant characterization of behavioral and striatal neurotransmitter response to amphetamine using in vivo microdialysis.

The temporal and dose-related behavioral and striatal monoamine response to amphetamine (AMPH) was examined using in vivo microdialysis in freely moving rats. Extracellular dopamine (DA), serotonin (5-HT), and their metabolites were monitored concomitant with detailed characterization of the locomotor and stereotypy profiles. Consistent with previous results, AMPH (0.5-5.0 mg/kg) induced a rapid dose-dependent increase in DA concentration and decrease in the concentrations of the DA metabolites, DOPAC and HVA. DA and its metabolites exhibited contrasting temporal and dose-related patterns, suggesting that the decline in DA metabolites is functionally dissociated from the AMPH-enhanced DA release. In addition, AMPH at doses of 2.0 mg/kg and greater significantly increased extracellular concentrations of 5-HT, which, in contrast to the changes in dopamine, persisted for only 20-40 min. Comparisons of concentrations of DA and 5-HT for individual animals revealed significant correlations both during baseline and drug response, suggesting a possible functional interdependence between dopaminergic and serotonergic activity in striatum. Dose-response comparisons revealed a significant relationship between AMPH-induced increases in behavioral perseveration and the magnitude and duration of the DA release. However, the temporal patterns of the neurotransmitter response and individual components of stereotypy were not parallel, suggesting that the presence of stereotypies is not associated simply with quantitative differences in striatal DA release. By contrast, some features of the behavioral response were significantly correlated with AMPH-induced changes in striatal 5-HT concentrations. Our results suggest that the behavioral response to AMPH may be influenced by the interaction between levels of DA and 5-HT release, as well as by the state of their respective receptors.

Amphetamine↗
PubMed1989

Unrecognized injuries of the lateral ligaments associated with lateral malleolar fractures of the ankle.

Of four patients who were treated between May 1985 and November 1987 and who had both a lateral malleolar fracture and a tear of the lateral ligaments of the ipsilateral ankle, three could be followed. The fractured malleolus was treated with rigid internal fixation, but the injury to the lateral ligaments was not diagnosed until the ankle was stressed to test for stability after the internal fixation. We believe that if disruption of the lateral ligaments is noted at operation, repair is indicated. This involves only a slight prolongation of time under anesthesia and markedly increases the chances for a stable ankle. It is important to check intraoperatively for a possible tear of the lateral ligaments in a patient who has a fracture of the ankle, especially when the injury was caused by high-energy trauma.

Adult↗
PubMed1988

Split-thickness skin excision in severe open fractures.

Split-thickness skin excision can be used as a one-stage procedure for the accurate diagnosis of flap viability and the immediate treatment of friction-avulsion injuries in severe open fractures. After cleaning the wound, the avulsed flap is temporarily sutured back to its original bed and a split thickness graft is taken from it and meshed to a 1:3 ratio. Surface dermal capillary bleeding then serves as an indicator of viability, clearly displaying a line for the excision of devascularized skin and correlating well with a concomitant fluorescein test. The wounds are re-opened and, after fixation of the fracture, the viable part of the flap is returned to its original bed and the remaining defects are covered with the meshed graft. We have treated 16 patients with extensive degloving injuries in this way, 15 needing only the single surgical procedure. All retained flaps survived, no other donor sites were needed and the split-thickness grafts took with 90% to 100% success.

Adolescent↗
PubMed1987

Tibial fractures with infrapopliteal arterial injuries.

Tibial fractures with associated infrapopliteal arterial injuries have been inadequately documented in the literature. Eighteen patients with these injuries were admitted to Boston City Hospital during a 10-year period. Three patients required below-knee amputation, and two of these had ischemic intervals of greater than 8 h before vascular treatment. Six patients had delayed diagnoses of arterial injuries, but none required amputation. There were 15 open and three closed tibial fractures. Nine fractures were badly comminuted. Eight of the 14 viable limbs had delayed unions, but only one was associated with local vascular insufficiency. Five patients had complaints attributed to vascular insufficiency without clinical findings. Our conclusion is that the limb with an infrapopliteal arterial insult combined with a tibial fracture can survive with patency of only the anterior tibial or posterior tibial artery. Poor clinical results correlate with the severity of bony injury and not with the particular arterial injury. The incidence of below-knee amputation can best be related to delay in vascular treatment.

Adolescent↗
PubMed1987

Flexible intramedullary nailing of tibial shaft fractures.

At the author's institution, flexible intramedullary nailing of long bones is most commonly used in tibial fractures. The 4.0-mm nails are most frequently used and are supplemented with the 3.5-mm nails. Over 95% of the nailed tibial fractures are stabilized in the antegrade method directed from the proximal tibia into the distal fragment. Retrograde nailing is done most often to supplement the stability of fractures in the distal third. Surgery can be performed on a standard fracture table with the patient placed on a radiotranslucent board; a biplanar image intensifier is required. Functional bracing is used four to six weeks after surgery. Early solid union is obtained even in comminuted fractures.

Bone Nails↗
PubMed1986

Alternative 5' exons and tissue-specific expression of the Drosophila EGF receptor homolog transcripts.

cDNA clones of the Drosophila epidermal growth factor receptor homolog (DER) gene were isolated and sequenced. The deduced amino acid sequence shows a similar degree of homology to the human epidermal growth factor receptor and to the rat and human neu proteins; the most striking difference is the addition of a third cysteine-rich extracellular domain in DER. The structure of the cDNA indicates the use of alternative 5' exons. Thus, the gene encodes three putative proteins differing at their N termini. The distribution of DER transcripts was analyzed by in situ hybridization. Transcripts are uniformly distributed in embryos, larval transcripts are primarily localized to proliferating tissues of the imaginal discs and brain cortex, and adult transcripts are detected mainly in the brain and ganglia. All three splicing alternatives show similar tissue distribution during development.

Age Factors↗
PubMed1986

Flexible medullary nailing of tibial shaft fractures.

Fifty-two tibial shaft fractures in 50 patients were treated with flexible medullary nails (Ender type). In 32 cases the fracture was closed and in the remaining 28 cases the fracture was open. Forty-eight of the 52 fractures united in an average time of 16.8 weeks and there were no cases of deep infection or osteomyelitis. Nonunion in four patients required a secondary procedure to obtain union. Flexible medullary nailing is an excellent method for fixation of tibial shaft fractures because it combines the benefits of closed nailing and functional bracing while minimizing the disadvantages of each. Three-point fixation within the medullary canal maintains length alignment and avoids rotational problems. Nailing is done by closed methods without reaming. The technique allows early weight-bearing in a patellar tendon bearing cast or functional brace. Dynamic controlled motion at the fracture site leads to early callus formation which is biomechanically and biologically favorable. The procedure is relatively easy to perform, short in duration, and requires little specialized equipment. Flexible medullary nailing is an alternative treatment modality for selected open and closed displaced tibial shaft fractures.

Adolescent↗
PubMed1986

Tissue localization of Drosophila melanogaster ras transcripts during development.

Three ras homologs have been identified in Drosophila melanogaster. Here we describe the tissue distribution of their transcripts as analyzed by in situ hybridization. The RNAs of the three genes show a similar distribution at every developmental stage examined. In embryos, the transcripts are uniformly distributed. In larvae, ras transcripts are restricted to dividing cells (e.g., imaginal disks, gonads, and brain). At the adult stage, several tissues contain ras transcripts. The strongest hybridization signals are localized to the adult ovaries and to the cortex of the brain and ganglia, which at this stage are comprised of differentiated, nondividing cells. The tissue distribution of ras transcripts in D. melanogaster suggests that the ras proteins have multiple roles during development which may be related to both the proliferative and differentiated states of the tissues.

Animals↗
PubMed1986

The Drosophila epidermal growth factor receptor homolog: structure, evolution, and possible functions.

A unique gene termed DER (Drosophila epidermal growth factor [EGF] receptor homolog) was isolated from Drosophila melanogaster and mapped to position 57F on the right arm of the second chromosome. The deduced amino acid sequence showed that the DER protein is 1409 amino acids long. In homology it is similar to the human EGF receptor and to rat and human neu proteins. The most striking difference between the Drosophila and human homologs is DER's additional 166 amino acids. The extra sequence is rich in cysteine residues and is another duplication of one of the two cysteine-rich regions, which are a hallmark of the EGF receptor and related proteins. Analysis of several cDNA clones of DER revealed variability at the 5' end of the coding region, demonstrating the presence of at least three splicing alternatives. All three transcripts have a similar tissue distribution during development: they are uniformly distributed in embryos, localized primarily in proliferating tissues in larvae, and found mainly in the brain cortex and the thoracic and abdominal ganglia in adults. The DER protein thus seems to have multiple roles during development, and it may represent a "universal" transducer of signals into the cell.

Animals↗
PubMed1986

Flexible intramedullary nailing of subtrochanteric fractures of the femur. A multicenter analysis.

In a retrospective, multicenter analysis, 79 subtrochanteric fractures of the femur were treated with flexible intramedullary nails. Seventy fractures were traumatic in origin, three were pathologic, and six occurred in spinal cord patients. All of the fractures healed, and there were no fixation failures. Thirteen patients (16%) required adjunctive internal fixation, bone grafts, or postoperative traction. Shortening greater than 1 cm occurred in four patients (5%). Reoperation with one week of surgery was necessary in eight patients (10%). The single greatest complication was knee complaints, which occurred in 17 patients (21.5%). However, only six of these patients required revision prior to fracture union. In one patient a deep wound infection developed, which eventually healed without evidence of osteomyelitis. All patients who were ambulatory before their fracture were able to bear weight.

Adolescent↗
PubMed1985

Allospecific cytolytic T lymphocytes recognize conformational determinants on hybrid mouse transplantation antigens.

Alloreactive cytolytic T cell (CTL) lines and clones have been used to identify the sites of polymorphism of antigens of the major histocompatibility complex (MHC). Specific CTL were generated against wild-type H-2b products by cells from H-2b mutant mice that had one or a few amino acid changes in either the alpha 1 or alpha 2 domains of the Kb or Db class I molecules. These CTL populations, which might be expected to react with determinants expressed on single MHC domains, were examined for lytic activity on L cells expressing newly constructed hybrid class I molecules. Transformed cell lines expressing native class I molecules or hybrid class I molecules in which the alpha 1 and alpha 2 domains of H-2Kb had been substituted by those domains of H-2Db were lysed by H-2Db-specific CTL. Similarly, all H-2Kb-specific CTL recognized hybrid molecules in which the alpha 1 and alpha 2 domains of H-2Kb were inserted into the H-2Db molecule. In contrast, exchange of the alpha 1 domains of H-2Kb and H-2Db resulted in a total loss of recognition by Kb and Db-specific CTL. These results suggest that the allodeterminants recognized by H-2 mutant CTL are influenced by interactions between the alpha 1 and alpha 2 domains, findings similar to those seen using conventional alloreactive T cells (11). These results were compared to the binding of alloreactive mAbs, including 5 new mAbs specific for the Kb molecules. Finally, it was shown that primary and secondary CTL responses could be generated by direct sensitization against hybrid class I molecules, demonstrating that these molecules express neoantigenic determinants recognized by alloreactive CTL.

Animals↗