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D Green

Publications and source records attributed to D Green.

At least 91 records · Page 5Linked to original sources
PubMed1999

A cyclic peptide analogue of the loop III region of platelet-derived growth factor-BB is a synthetic antigen for the native protein.

We report the synthesis and characterization of a cyclic peptide analogue of the loop III region of platelet-derived growth factor (PDGF) B-chain sequence, cyclo(73Arg-Lys-Ile-Glu-Ile-Val-Arg-Lys-Lys81-Cys), incorporating a C-terminus cysteine residue for the conjugation to a carrier protein. The synthesis involved solid-phase chemistry, utilizing Fmoc-tBu chemistry and acid labile side-chain protecting groups, followed by 'head-to-tail' cyclization using the allyl-protected glutamic acid anchored on its side chain to the solid support with HATU/HOAt as the coupling agent. Conformational differences between the cyclic and its linear counterpart PDGF peptides were determined by circular dichroism measurements in aqueous media. High titre antisera were raised to both cyclic and linear peptide immunogens. Antisera raised to the cyclic peptide cross-reacted with PDGF-BB in both Western blot and ELISA, whereas antisera raised to the linear peptide had no reactivity with PDGF-BB. The cyclic peptide (conformational design analogue) produces an immunogen which is able to antigenically mimic the secondary structure of loop III of PDGF-BB and forms a basis from which further small molecular mimetics of PDGF may be designed for use as both immunogens and also potential agonists/antagonists of PDGF. Similarly constructed immunogens may also be useful in the design of vaccines which direct responses to loop regions in other target proteins.

Animals↗
PubMed1999

Isolation of Providencia heimbachae from human feces.

Providencia heimbachae was first described in 1986. It has been isolated from penguin feces and an aborted bovine fetus. To date, there has been no reported isolation of this organism from human specimens. We now report the isolation of P. heimbachae from the stool of a 23-year-old woman with idiopathic diarrhea. The identity of the human strain was determined biochemically and by DNA relatedness to the type strain of P. heimbachae.

Adult↗
PubMed1999

Role of adjuvant chemotherapy in the treatment of surgically resected pediatric nonrhabdomyosarcomatous soft tissue sarcomas: A Pediatric Oncology Group Study.

PURPOSE: To prospectively study the value of adjuvant chemotherapy in pediatric patients with surgically resected nonrhabdomyosarcomatous soft tissue sarcomas (NRSTS). PATIENTS AND METHODS: From June 1986 to May 1992, after complete surgical resection (+/-radiotherapy) of their NRSTS, 81 eligible patients either received adjuvant chemotherapy comprising vincristine, dactinomycin, cyclophosphamide, and doxorubicin or were observed. Only 30 patients accepted randomization, and 15 were assigned to each regimen. Of the remaining 51 patients, 19 elected adjuvant chemotherapy and 32 elected observation. RESULTS: Patients were predominantly male, and 69% of all patients were white. The median age at diagnosis was 12.3 years (range, 9.2 to 20.7 years). For the 81 eligible patients, the 5-year overall survival estimate was 84.5% +/- 4.4% and event-free survival was 72.2% +/- 5.4%. Among randomized patients, the 5-year estimated overall survival rate was 93.3% +/- 7%, and the event-free survival rate was 86.7% +/- 9.5% for the observation group, compared with 69.2% +/- 13% and 40.7% +/- 14%, respectively, for those who received chemotherapy. The significantly worse outcome of patients who received adjuvant chemotherapy disappeared when survival was stratified by tumor grade. Among all patients, a grade 3 lesion conferred a significant disadvantage with respect to event-free survival (P =.0001). CONCLUSION: The administration of adjuvant chemotherapy according to the schedule and dosages used in our trial did not improve the outcome of children with resected NRSTS. In this study, tumor grade was the most important predictor of clinical outcome in patients with resected NRSTS, and this factor should be incorporated into the stratification of patients in future trials.

Adolescent↗
PubMed1999

Current trends in the use of heparins in thromboprophylaxis.

Unfractionated heparin (UH), administered subcutaneously in low doses of 5000 U every 12 h, is safe and effective in preventing thrombosis in most patients. However, in persons with neurological disease, surgical replacement of joints, or operations for cancer, low-dose UH is often inadequate or unsafe, and dose-adjusted UH, warfarin, or low molecular weight heparins (LMWH) may be needed. In trauma patients, LMWH is significantly more effective than UH in reducing the frequency of DVT with a minimal increase in bleeding risk. LMWH also significantly decreases thromboembolism in patients with acute spinal cord injury and complete motor paralysis, and with less bleeding as compared to UH. In acute stroke, a heparinoid was more effective than either placebo or UH (5000 U every 12 h) in preventing deep-vein thrombosis in acute thrombotic stroke, and the risk of bleeding was low. Following total hip or knee replacement, LMWH is more efficacious than warfarin but may be associated with perioperative bleeding. The duration of thrombo-prophylaxis following arthroplasty is controversial; venography demonstrates thrombi in approximately 29% of patients after hospital discharge, but only 3% have clinical symptoms. Lastly, perioperative thrombosis in cancer patients having abdominal surgery has been decreased by LMWH, and experience with outpatient treatment in the long-term management of Trousseau's syndrome has been positive.

Anticoagulants↗
PubMed1998

Crystal structure of an angiogenesis inhibitor bound to the FGF receptor tyrosine kinase domain.

Angiogenesis, the sprouting of new blood vessels from pre-existing ones, is an essential physiological process in development, yet also plays a major role in the progression of human diseases such as diabetic retinopathy, atherosclerosis and cancer. The effects of the most potent angiogenic factors, vascular endothelial growth factor (VEGF), angiopoietin and fibroblast growth factor (FGF) are mediated through cell surface receptors that possess intrinsic protein tyrosine kinase activity. In this report, we describe a synthetic compound of the pyrido[2,3-d]pyrimidine class, designated PD 173074, that selectively inhibits the tyrosine kinase activities of the FGF and VEGF receptors. We show that systemic administration of PD 173074 in mice can effectively block angiogenesis induced by either FGF or VEGF with no apparent toxicity. To elucidate the determinants of selectivity, we have determined the crystal structure of PD 173074 in complex with the tyrosine kinase domain of FGF receptor 1 at 2.5 A resolution. A high degree of surface complementarity between PD 173074 and the hydrophobic, ATP-binding pocket of FGF receptor 1 underlies the potency and selectivity of this inhibitor. PD 173074 is thus a promising candidate for a therapeutic angiogenesis inhibitor to be used in the treatment of cancer and other diseases whose progression is dependent upon new blood vessel formation.

3T3 Cells↗
PubMed1998

Bifunctional peptide boronate inhibitors of thrombin: crystallographic analysis of inhibition enhanced by linkage to an exosite 1 binding peptide.

The affinity of the hirudin49-64 segment for exosite 1 of thrombin has been used previously to enhance the potency of simple competitive inhibitors [DiMaio, J., Gibbs, B., Munn, D., Lefebvre, J. , Ni, F., Konishi, Y. (1990) J. Biol. Chem. 265, 21698-21703., and Maraganore, J. M., Bourdon, P., Jablonski, J., Ramachandran, K. L., and Fenton, J. W., II (1990) Biochemistry 29, 7095-7087.]. Using a similar approach, we have enhanced the activity of two active site directed thrombin inhibitors by attaching this segment via a novel reverse oriented linker to each of two tripeptide boronate inhibitors. At P1, compound 1 contains an arginine-like, isothiouronium, side chain, while compound 2 contains an uncharged, bromopropyl residue. Inhibition of human alpha-thrombin by compound 1 shows slow, tight-binding competitive kinetics (final Ki of 2.2 pM, k1 of 3.51 x 10(7) M-1 s-1, and k-1 of 1.81 x 10(-)4 s-1). The addition of hirugen peptide (20 microM) competes for exosite 1 binding and restores the k1 and k-1 to that of the analogous tripeptide, 0.29 x 10(7) M-1 s-1 and 0.13 x 10(-)4 s-1, respectively. Compound 1 has enhanced specificity for thrombin over trypsin with KiTry/KiThr of approximately 900 compared to the analogous tripeptide, with KiTry/KiThr of approximately 4. Compound 2 acts as a competitive inhibitor (KiThr of 0.6 nM) and is highly selective with no effect on trypsin. Crystallographic analysis of complexes of human alpha-thrombin with compound 1 (1.8 A) and compound 2 (1.85 A) shows a covalent bond between the boron of the inhibitor and Ser195 (bond lengths B-O of 1.55 and 1.61 A, respectively). The isothiouronium group of compound 1 forms bidentate interactions with Asp189. The P2 and P3 residues of the inhibitors form interactions with the S2 and S3 sites of thrombin similar to other D-Phe-Pro based inhibitors [Bode, W., Turk, D., and Karshikov, A. (1992) Protein Sci. 1, 426-471.]. The linker exits the active site cleft of thrombin forming no interactions, while the binding of Hir49-64 segment to exosite 1 is similar to that previously described for hirudin [Rydel, T. J., Tulinsky, A., and Bode, W. (1991) J. Mol. Biol. 221, 583-601.]. Because of the similarity of binding at each of these sites to that of the analogous peptides added alone, this approach may be used to improve the inhibitory activity of all types of active site directed thrombin inhibitors and may also be applicable to the design of inhibitors of other proteases.

Amino Acid Sequence↗
PubMed1998

Thrombotic thrombocytopenic purpura associated with ticlopidine. A review of 60 cases.

BACKGROUND: Thrombotic thrombocytopenic purpura, a life-threatening multisystem disease, has been infrequently associated with use of ticlopidine, a platelet anti-aggregating agent. PURPOSE: To review 60 cases of ticlopidine-associated thrombotic thrombocytopenic purpura. DATA SOURCES: Medical records, published case reports, and case reports submitted to the U.S. Food and Drug Administration. STUDY SELECTION: Instances of ticlopidine-associated thrombotic thrombocytopenic purpura were identified. DATA SYNTHESIS: Ticlopidine had been prescribed for less than 1 month in 80% of the patients, and normal platelet counts had been found within 2 weeks of the onset of thrombotic thrombocytopenic purpura in most patients. Mortality rates were higher among patients who were not treated with plasmapheresis than among those who underwent plasmapheresis (50% compared with 24%; P < 0.05). CONCLUSIONS: Ticlopidine use may be associated with the development of thrombotic thrombocytopenic purpura, usually within 1 month of initiation of therapy. The onset of ticlopidine-associated thrombotic thrombocytopenic purpura is difficult to predict, despite close monitoring of platelet counts.

Adult↗
PubMed1998

Dihydropyrancarboxamides related to zanamivir: a new series of inhibitors of influenza virus sialidases. 1. Discovery, synthesis, biological activity, and structure-activity relationships of 4-guanidino- and 4-amino-4H-pyran-6-carboxamides.

4-Amino- and 4-guanidino-4H-pyran-6-carboxamides 4 and 5 related to zanamivir (GG167) are a new class of inhibitors of influenza virus sialidases. Structure--activity studies reveal that, in general, secondary amides are weak inhibitors of both influenza A and B viral sialidases. However, tertiary amides, which contain one or more small alkyl groups, show much greater inhibitory activity, particularly against the influenza A virus enzyme. The sialidase inhibitory activities of these compounds correlate well with their in vitro antiviral efficacy, and several of the most potent analogues displayed useful antiviral activity in vivo when evaluated in a mouse model of influenza A virus infection. Carboxamides which were highly active sialidase inhibitors in vitro also showed good antiviral activity in the mouse efficacy model of influenza A infection when administered intranasally but displayed modest activity when delivered by the intraperitoneal route.

Administration, Intranasal↗
PubMed1998

Diagnosis of von Willebrand disease type 2N: a simplified method for measurement of factor VIII binding to von Willebrand factor.

Diagnosis of von Willebrand disease Type 2N (vWD 2N), which mimics hemophilia A and its carrier state, is important for accurate genetic counseling and appropriate therapy. To make testing for the disorder more clinically applicable, we developed a simplified method for measurement of factor VIII (FVIII) binding to von Willebrand factor (vWF) using commercially available reagents and standard clinical assays. FVIII binding to vWF was measured by capture of patient vWF by polyclonal antibodies on cyanogen bromide-activated Sepharose beads, reaction with recombinant FVIII, and assay of unbound FVIII by clotting methods. Unbound vWF was measured in patient plasma after capture by the Laurell method. The ratio of bound FVIII/bound vWF was normal in hemophilia A, vWD Type 1, and vWD Type 3 patients, and abnormal in 5 subjects from two families, all of whom had vWD 2N mutations. Patient 1, with FVIII 8 U/dl, vWF: Ag 61 U/dl, vWF:RC 74 U/dl, and FVIII binding nil, was homozygous for the Arg91 Gln mutation. She was followed during pregnancy and delivered an unaffected heterozygous son. Patient 2 had FVIII 8 U/dl, vWF:Ag 73 U/dl, and vWF:RC 71 U/dl, and very low FVIII binding. She was heterozygous for Arg91Gln, as were her mother and sister; no second vWD 2N mutation was found. Her brother, with FVIII 14 U/dl, vWF:Ag 113 U/dl, and vWF:RC 72 U/dl, has no evidence of vWD 2N. With an X-linked inheritance pattern of bleeding tendency, this family is the first reported with combined hemophilia A and vWD 2N.

Adult↗
PubMed1998

Treatment of unresectable or metastatic pediatric soft tissue sarcomas with surgery, irradiation, and chemotherapy: a Pediatric Oncology Group study.

BACKGROUND: The objectives of this study were to compare vincristine/actinomycin D/cyclophosphamide/adriamycin (VACA) with VACA/plus imidazole carboxamide (DTIC) (VACAD) therapy in regards to complete/partial response and event free survival rates in children and adolescents with metastatic non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) or previously chemotherapy-naive recurrent NRSTS or locally persistent gross residual tumor after surgery and radiation therapy. PROCEDURES: Between 1986 and March 1994, 75 patients entered this randomized study comparing VACA and VACAD, given at 3 week intervals. Sixty-one patients were considered eligible and received chemotherapy and radiation therapy to the primary tumor and areas of metastases. Thirty-six patients had regional unresected (Group III) disease, and 25 had metastatic disease (Group IV) at time of accession. Thirty-six patients received VACA (11 were not randomized), and 25 received VACAD. RESULTS: With a median follow-up of greater than 4 years, overall and event-free survival for all eligible patients are 30.6% and 18.4% respectively (S.E: 9.5% and 6.8%). There was insufficient evidence that DTIC offered any advantage to event free survival, but there was evidence for better outcome for patients in Group III disease in comparison to patients with Group IV disease, and for patients with a Grade 1 and 2 histology in comparison to Grade 3 lesions. CONCLUSIONS: Combination chemotherapy with VACA and VACAD were insufficient to prevent recurrent or progressive disease in children and adolescents with high stage NRSTS. The use of vincristine/ifosfamide/doxorubicin with cytokine support is under study.

Adolescent↗
PubMed1998

Stromal-conditioned medium synergizes with thrombopoietin in stimulating megakaryocytopoiesis.

We previously demonstrated that stromal cells release a soluble factor(s) that enhances thrombopoietin (TPO)-induced megakaryocyte (MK) production. We have now further characterized this enhancing activity of human bone marrow stroma and have also analyzed the role of direct contact of stromal cells with human bone marrow CD34+ cells on MK production. The three- to sixfold stromal-enhancing activity of conditioned media is constitutive and is not influenced by the presence of TPO. The addition of interleukins 3, 6 (IL-3, IL-6), stem cell factor (SCF), and TPO at concentrations found in stroma to a stroma-free system only enhanced by 58% the TPO-stimulated MK production. No influence of heparan sulfates on MK production was observed. In co-cultures of CD34+ cells in direct contact with stromal cells, nonadherent and adherent MK, and proplatelet structures were observed, either in the absence or presence of TPO. Direct contact did not further improve the enhancing activity of stromal cells on MK production induced by TPO. We conclude that the stromal enhancement of MK production is neither accounted for by stromal TPO, IL-3, IL-6, and SCF activities nor modified by physical contact.

Cell Adhesion↗
PubMed1998

Sclerotherapy for the permanent eradication of varicose veins: theoretical and practical considerations.

Although sclerotherapy is an established procedure to treat ectatic veins, a wide disparity remains in the reported rates of success, especially for larger varicose veins. This article reviews the venous anatomy of the lower extremity and outlines the indications for sclerotherapy. The historical basis for treatment techniques is explored. The mechanism of action of sclerotherapy is discussed as a basis for treatment guidelines. If the procedure is properly performed, when appropriately indicated, rates of success should approach 100%.

Humans↗
PubMed1998

Photothermal removal of telangiectases of the lower extremities with the PhotodermVL.

BACKGROUND: Telangiectases of the lower extremities have been refractory to permanent ablation by photothermal coagulation. In addition, adverse effects often occur because of nonselective absorption of the light by the overlying skin. OBJECTIVE: This study was performed to determine the effectiveness and the incidence of adverse effects associated with the PhotodermVL in the treatment of telangiectases, less than 0.4 mm in diameter, of the lower extremities. METHODS: Seventy-two patients were treated, each at one treatment site, by means of a treatment protocol designed by ESC Medical Systems, Ltd., the developer and manufacturer of the PhotodermVL. RESULTS: Complete, or almost complete, clearance of telangiectases was observed in 10% of patients. No improvement occurred in 56% of treated telangiectases, and 25% had partial clearing. Adverse effects were common, including scarring in 21% of patients. CONCLUSION: The PhotodermVL provided a low rate of success in the treatment of telangiectases on the lower extremities. Treatment was associated with a high rate of adverse effects.

Adolescent↗
PubMed1998

Organ procurement in an urban level I emergency department.

STUDY OBJECTIVE: To determine whether an intensive educational campaign of emergency department personnel on the organ donor and procurement process would result in both increased organ donor referrals and organs procured. METHODS: A retrospective review of the performance of an urban teaching ED in identifying and referring potential organ donor candidates was performed. Subsequently an intensive educational campaign of all ED staff, in conjunction with the Regional Organ Procurement Agency of Southern California (ROPA), was initiated. Physicians and nurses were educated about the procurement process, and a ROPA representative was on call 24 hours a day to assist in this process. The need for aggressive resuscitation and vital sign maintenance in potential donors as a strategy to promote organ recovery was emphasized. Reeducation by ROPA occurred every 2 to 3 months. The identification and referral rates were then retrospectively reviewed to evaluate any improvement. RESULTS: In 1994 the initial referral rate of potential organ donors from the ED was 30% (3 of 10) resulting in no organs procured. After the intervention the referral rate increased to 100% (25 of 25) in 1995 (P < .0001). The number of actual donors procured was 0 in 1994, 5 in 1995, and 9 in 1996. The increased ED referrals resulted in 14 and 32 organs procured in 1995 and 1996, respectively. CONCLUSION: Emergency physicians are in a unique position as first caregivers to interact with both potential donors and their families. With intensive education of ED staff, proper identification and referral, as well as timely intervention by organ procurement representatives, the consent and donation rate of organs for transplantation can be increased and maintained.

Accidents, Traffic↗
PubMed1998

Sclerotherapy treatment insights.

The permanent eradication of ectatic veins while minimizing the incidence of adverse effects, minimizing patient discomfort, and treating the maximal number of veins during each session are goals of injection sclerotherapy. Accomplishing these goals requires more than skill at cannulation and injection into a vein. An understanding of the mechanism of action of sclerotherapy, and knowledge of lower extremity venous anatomy and hemodynamics are crucial. Insuring a satisfactory outcome also requires that the patient is thoroughly informed about the procedure and its possible risks. In addition to addressing these issues, this author presents the salient aspects of his pretreatment consultation, posttreatment recommendations, and appropriate documentation.

Humans↗
PubMed1998

The central executioners of apoptosis: caspases or mitochondria?

Apoptosis is a type of cell death whose morphological appearance relies on the activation of caspase-family cysteine proteases. Recently, it has become clear that inhibition of caspases does not always prevent irreversible loss of cellular function, although it does prevent the acquisition of apoptotic morphology. Alterations in mitochondrial membrane structure and function can occur in a caspase-independent fashion and have a higher predictive value for cell death than caspase activation. Here, Douglas Green and Guido Kroemer argue that caspases might have a dual function in the apoptotic process: first, as signal-transduction molecules that act as facultative inducers of mitochondrial membrane changes, and, second, as processing enzymes that orchestrate the apoptotic phenotype. They propose a model for initiation of apoptosis in which mitochondria and caspases engage in a self-amplifying pathway of mutual activation.

Animals↗