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P Robbins

Publications and source records attributed to P Robbins.

At least 37 records · Page 2Linked to original sources
PubMed2000

Vector systems for gene transfer to joints.

The prospects for the development of gene therapy treatments for certain orthopaedic diseases have been fueled by advances in the understanding of the molecular components of these disorders. These studies have identified molecules that could have therapeutic or reparative effects in certain settings. The ability to transfer and appropriately express the genes encoding these molecules is dependent on the availability of effective gene transfer vectors. Numerous vector systems have been used to transfer and express genes in joints with varied levels of success. The current review is designed to briefly outline the basics of the different gene transfer vector systems available for use by researchers in the orthopaedic fields.

Adenoviridae↗
PubMed2000

Potential of gene therapy for treating osteogenesis imperfecta.

Osteogenesis imperfecta is a heterogeneous group of genetic disorders that affect connective tissue integrity, with bone fragility being the major clinical feature. Most forms of osteogenesis imperfecta are the result of mutations in the genes that encode the pro alpha1 and pro alpha2 polypeptide chains of Type I collagen. Because osteogenesis imperfecta is an incurable genetic disease, cell therapy and gene therapy are being investigated as potential treatments. Gene therapy for osteogenesis imperfecta however is a major challenge; because most of the mutations in osteogenesis imperfecta are dominant negative, supplying the normal gene without silencing the abnormal gene may not be beneficial. Null mutations in which an allele is not expressed or absent may be amenable to gene therapy or alternatively after silencing a mutant allele, a normal gene could be supplied. In addition, overexpression of the normal collagen gene in cells expressing mutant collagen polypeptide chains potentially could lead to synthesis of a sufficient percentage of normal molecules to normalize clinical status. The authors currently are examining the possibility of developing gene therapy for treating a mouse model of human osteogenesis imperfecta (oim) using bone marrow stromal cells as vehicles for delivering normal collagen genes to bone. In the current study, the potential of gene therapy for treating osteogenesis imperfecta is discussed in the context of the complexity of the mutations in Type I collagen genes that lead to different osteogenesis imperfecta phenotypes.

Animals↗
PubMed2000

Routine analysis of p53 mutation in clinical breast tumor specimens using fluorescence-based polymerase chain reaction and single strand conformation polymorphism.

Improved prognostic and predictive markers in breast cancer management would help considerably in therapeutic decision making, particularly in patients with early-stage breast cancer. Tumor factors currently used for prognostication and management decisions are tumor size, histologic type and grade, axillary lymph node status, and estrogen receptor content. The discovery of various somatic genetic alterations in breast cancer has raised the possibility that these may provide additional and independent prognostic and predictive information. Alterations of the p53 tumor suppressor gene in particular have received the most attention as potential prognostic and predictive factors. In multivariate analysis, p53 gene mutation is consistently associated with a two- to threefold increased risk of relapse and death from breast cancer. One of the major reasons preventing the introduction of p53 mutation as a routine marker to assist in therapeutic decision making is the lack of a simple, reproducible, and inexpensive assay. In the present study the authors optimized a polymerase chain reaction-based mutation screening method, fluorescence-single strand conformation polymorphism (F-SSCP), that allows p53 status to be assessed accurately and reproducibly in routinely handled, formalin-fixed and paraffin-embedded tumor specimens. The frequency of p53 mutation observed using F-SSCP in a consecutive series of invasive ductal breast carcinomas was 17% (28/164). The authors propose that the prognostic and predictive values of p53 mutation in breast cancer should be further evaluated in prospective, randomized studies using this standardized technique.

Adult↗
PubMed2000

The most abundant glycoprotein of amebic cyst walls (Jacob) is a lectin with five Cys-rich, chitin-binding domains.

The infectious stage of amebae is the chitin-walled cyst, which is resistant to stomach acids. In this study an extraordinarily abundant, encystation-specific glycoprotein (Jacob) was identified on two-dimensional protein gels of cyst walls purified from Entamoeba invadens. Jacob, which was acidic and had an apparent molecular mass of approximately 100 kDa, contained sugars that bound to concanavalin A and ricin. The jacob gene encoded a 45-kDa protein with a ladder-like series of five Cys-rich domains. These Cys-rich domains were reminiscent of but not homologous to the Cys-rich chitin-binding domains of insect chitinases and peritrophic matrix proteins that surround the food bolus in the insect gut. Jacob bound purified chitin and chitin remaining in sodium dodecyl sulfate-treated cyst walls. Conversely, the E. histolytica plasma membrane Gal/GalNAc lectin bound sugars of intact cyst walls and purified Jacob. In the presence of galactose, E. invadens formed wall-less cysts, which were quadranucleate and contained Jacob and chitinase (another encystation-specific protein) in secretory vesicles. A galactose lectin was found to be present on the surface of wall-less cysts, which phagocytosed bacteria and mucin-coated beads. These results suggest that the E. invadens cyst wall forms when the plasma membrane galactose lectin binds sugars on Jacob, which in turn binds chitin via its five chitin-binding domains.

Amino Acid Sequence↗
PubMed2000

Interleukin-2: developing additional cytokine gene therapies using fibroblasts or dendritic cells to enhance tumor immunity.

PURPOSE: Recombinant interleukin (IL)-2 administration can mediate regression of solid tumors in patients with melanoma and renal cell carcinoma. A better understanding of the mechanisms of IL-2-mediated antitumor effects has led to the investigation of novel immunotherapeutic approaches. The rationale for these immunotherapeutic approaches and the results of preliminary clinical studies are presented. PATIENTS AND METHODS: The therapeutic potential of dendritic cells and the role of FLT3 ligand, a potent hematopoietic growth factor, was investigated in a variety of preclinical models. In addition, a clinical study with autologous dendritic cells pulsed with synthetic melanoma peptides derived from the MART1/ Melan A, gp100, and tyrosinase proteins was conducted. Twenty-eight human leukocyte antigen (HLA)-A2+ melanoma patients received an average of 106 dendritic cells a week for 4 weeks. RESULTS: In a murine liver metastases model, FLT3 ligand administration alone or in combination with IL-12 or IL-2 had significant antitumor effects and resulted in significant infiltration of the tumor border by lymphocytes and dendritic cells, which was associated with an increased number of apoptotic figures. Administration of melanoma peptide-pulsed dendritic cells to 28 patients with advanced metastatic melanoma produced a complete response in two patients and a partial response in one. Significant infiltration of T cells and dendritic cells into melanoma lesions was observed. CONCLUSION: These studies confirm the feasibility of immunotherapeutic approaches using dendritic cells and FLT3 ligand and demonstrate their potential antitumor activity. These approaches may be effective for patients with metastatic melanoma and other solid tumors and will likely be used to improve the efficacy of IL-2-based immunotherapy.

Cancer Vaccines↗
PubMed1999

Gene therapy in transplantation.

Facilitation of solid organ and cell transplantation depends on metabolic and immunologic factors that can be manipulated ex vivo and in vivo using gene transfer technology. Vectors have been developed which can optimally transfer relevant genes to various tissues and organs. Interventions aimed at promoting tissue preservation before transplantation, prevention of oxidative stress and immunological rejection have recently become attractive options using viral and nonviral gene delivery vehicles. Further understanding of the mechanisms involved in tolerance induction as well as the facilitation of xenogeneic engraftment have made possible a variety of avenues that can be exploited using gene transfer technology.

Animals↗
PubMed1999

Infection of intact human islets by a lentiviral vector.

The transfer of genes encoding immunomodulatory proteins to islets can be used to improve islet function, block apoptosis, and inhibit rejection following transplantation. Adenoviral vectors have been shown to infect intact human islets, but the immunogenicity and transient gene expression of the current adenoviral vectors may hinder their use clinically for islet transplantation. In this report, we compared an HIV-1-based lentiviral vector with the E1-deleted adenoviral vehicle of the Ad5 type for gene transfer to human islets in vitro. We demonstrate that at similar viral particle concentrations per islet that an HIV-based lentiviral vector is able to infect beta-cells within an intact human islet at an efficiency similar to an adenoviral vector. In addition, both the adenoviral and lentiviral vectors were able to express significant levels of soluble interleukin-1 receptor antagonist (IL-1Ra) protein following infection of intact islets. More importantly, there was no impairment of islet beta-cell function following adenoviral and lentiviral infection in responding to glucose stimulation. These results support the utility of replication-defective lentiviral vectors as efficient gene delivery vehicles to islets to faciliate transplantation of islets for therapy of type I diabetes.

Adenoviridae↗
PubMed1999

Intra-articular delivery of a herpes simplex virus IL-1Ra gene vector reduces inflammation in a rabbit model of arthritis.

To evaluate the use of HSV-based vectors for arthritis gene therapy we have constructed a first-generation, ICP4 deficient, replication defective herpes simplex virus (HSV) vector (S/0-) and a second-generation HSV vector derivative (T/0-) deficient for the immediate-early genes ICP4, 22 and 27, each carrying a soluble TNF receptor or IL-1 receptor antagonist transgene cassette. A rabbit synovial-fibroblast line in culture, infected by either vector enabled high-level expression of the transgene product. However, following a single intra-articular injection of the vectors into rabbit knee joints, only the second-generation, HSV T/0- vector expressed detectable levels of soluble TNFR in synovial fluid. Synovial lavage fluid from inoculated joints con- tained up to 12 ng/ml of soluble receptor that persisted at detectable, but reduced levels for at least 7 days. When tested in an experimental model of arthritis generated by intra-articular overexpression of interleukin-1beta using retrovirus transduced synovial cells, the HSV T/0- vector expressing the interleukin-1 receptor antagonist was found to inhibit leukocytosis and synovitis significantly. The improved levels and duration of intra-articular transgene expression achieved via HSV-mediated gene delivery suggest that an HSV vector system could be used for therapeutic applications in patients with rheumatoid arthritis (RA) and other joint-related inflammatory diseases.

Adoptive Transfer↗
PubMed1999

Familial fatal and near-fatal third ventricle colloid cysts.

BACKGROUND: Despite having a presumed congenital origin, familial cases of colloid cysts have been reported only rarely. The first case of a brother and sister with colloid cysts is reported here, and the relevant literature is reviewed. METHODS: A 25-year-old man presented with a 24-h history of headache and vomiting. He rapidly became unconscious and fulfilled the criteria for brain death on arrival at hospital. No surgical intervention was performed. RESULTS: The patient's sister presented at the age of 41 with headaches and rapidly became unconscious. The sister had urgent bilateral ventriculostomies. followed by transcallosal removal of a colloid cyst. CONCLUSIONS: These cases support the hypothesis that colloid cysts are congenital lesions and provide some evidence of a possible genetic predisposition to their formation. Sudden death remains a real risk for patients harbouring a colloid cyst.

Adult↗
PubMed1999

Pre-operative chemoradiotherapy in locally advanced rectal cancer.

BACKGROUND: The aim of the present study was to investigate the effectiveness and toxicity of pre-operative chemoradiation in locally advanced rectal cancer (T3-T4). METHODS: Forty-seven patients were assessed (38 T3 and nine T4 tumours). Pre-operative pelvic radiotherapy was delivered in four fields, 45 Gy in 25 fractions over 5 weeks. Bolus 5-fluorouracil (5-FU) was delivered 500 mg/m2 on days 1, 2, 3 and days 22, 23, 24. Total mesorectal excision of the rectal tumour either by anterior or abdomino-perineal resection was planned at 4-6 weeks from completion of pre-operative treatment. Response to therapy was assessed by fresh macroscopic measurement of the surgical specimen. RESULTS: All patients undergoing chemoradiation completed therapy as planned, with no treatment-related interruptions. The regimen had a low acute toxicity profile with an estimated 50% or greater response in 38 out of 47 patients (four patients had complete responses). Forty-three (97%) of 44 patients who underwent surgery were operable. Patients who were operated on between 4 and 7 weeks had a statistically better response then those who were operated on after 7 weeks (P = 0.013; Fisher's exact test). Eight of 10 patients who were considered to be inoperable prior to the treatment underwent total mesorectal excision with negative radial margins. Anastomotic leakage occurred in four patients (9%); one required surgical intervention. Wound infection occurred in three patients (6%); one patient required re-exploration for haemorrhage. Delayed complications occurred in three patients (6%); one requiring surgery for a stomal stricture. After a median follow-up of 20 months, two patients (4%) had developed local recurrence. CONCLUSION: The pre-operative chemoradiation regimen employed had a low acute toxicity profile and all patients completed therapy. The majority of patients considered inoperable prior to receiving this treatment underwent successful excision. Appropriately fractionated pre-operative chemoradiotherapy is a reasonable option in this disease and deserves further evaluation.

Adenocarcinoma↗
PubMed1999

Pre-operative chemo-radiotherapy in locally advanced rectal cancer: is this the way of future management?

The purpose of the present paper was to update a prospective analysis (H Elsaleh et al. unpubl. data, 1997) investigating the effectiveness and toxicity of pre-operative pelvic radiotherapy with modest dose 5-fluorouracil (5-FU) in locally advanced rectal cancer (T3-T4). A total of 31 patients were assessed (28 T3 and three T4 tumours). Pre-operative pelvic radiotherapy was delivered in four fields, 45 Gy to the International Commission on Radiation Units and Measurements (ICRU) point in 25 fractions over 5 weeks. A radiosensitizing dose of 5-FU was delivered at 500 mg/m2 on days 1, 2 and 3, and days 22, 23 and 24. Mesorectal excision of the rectal tumour either by anterior or abdomino-perineal resection was planned at 4-6 weeks from completion of pre-operative treatment. Response to therapy was assessed by fresh macroscopic measurement of the surgical specimen. Patients had a low toxicity profile; an estimated 50% or greater response was seen in 24 out of 31 (two complete responses). There were no surgical difficulties achieving resection. No late complications were documented, although follow-up was short. In locally advanced rectal cancer, pre-operative chemo-radiotherapy had a low toxicity profile. Appropriately fractionated pre-operative chemo-radiotherapy is a reasonable option in this disease and should be further evaluated. The optimal method of delivery of the radiosensitizing agent (5-FU) is the subject of further investigation.

Adult↗
PubMed1999

Pituitary abscess.

A 28-year-old Caucasian woman presented with a 12 month history of secondary amenorrhoea, polyuria and polydipsia with fatigue and weight loss. Investigations revealed panhypopituitarism, diabetes insipidus, an intrasellar mass and papilloedema, thought to be due to benign intracranial hypertension. She was treated conservatively. However, a repeat magnetic resonance image showed enlargement of the pituitary mass with compression of the optic nerves. The pituitary abscess was drained by a transsphenoidal approach. Postoperatively the patient received antibiotics with no recurrence of the pituitary abscess. Copyright 1999 Harcourt Publishers Ltd.

Journal Article↗
PubMed1998

Stable transduction of the interleukin-2 gene into human natural killer cell lines and their phenotypic and functional characterization in vitro and in vivo.

A variety of strategies have been attempted in the past to stably transduce natural killer (NK) cells with cytokine or other cellular genes. Here, we demonstrate the successful delivery of the interleukin-2 (IL-2) gene into two human NK cell lines, IL-2-dependent NK-92 and IL-2-independent YT, by retroviral transduction. An MuLV-based retroviral vector expressing human IL-2 and neor markers from a polycistronic message was constructed and transduced into a CRIP packaging cell line. By coincubation of NK cells with monolayers of CRIP cells or by using retrovirus-containing supernatants in a flow-through method, 10% to 20% of NK cells were stably transduced. Upon selection in the presence of increasing G418 concentrations, transduced NK cells were able to proliferate independently of IL-2 for more than 5 months and to secrete up to 5.5 ng/10(6) cells/24 h of IL-2. IL-2 gene-transduced NK-92 cells had an in vitro cytotoxicity against tumor targets that was significantly higher than that of parental cells and secreted interferon gamma (IFNgamma) and tumor necrosis factor alpha (TNFalpha) in addition to IL-2. Moreover, the in vivo antitumor activity of IL-2 gene-transduced NK-92 cells against established 3-day liver metastases in mice was greater than that of parental nontransduced NK cells. Stable expression of the IL-2 transgene in NK cells improved their therapeutic potential in tumor-bearing hosts. Thus, transduced NK cells secreted sufficient quantities of bioactive IL-2 to proliferate in vitro and mediated the antitumor effects both in vitro and in vivo in the absence of exogenous IL-2. These results suggest that genetic modification of NK cells ex vivo could be useful for clinical cancer therapy in the future.

Animals↗
PubMed1997

Stabilization of beta-catenin by genetic defects in melanoma cell lines.

Signal transduction by beta-catenin involves its posttranslational stabilization and downstream coupling to the Lef and Tcf transcription factors. Abnormally high amounts of beta-catenin were detected in 7 of 26 human melanoma cell lines. Unusual messenger RNA splicing and missense mutations in the beta-catenin gene (CTNNB1) that result in stabilization of the protein were identified in six of the lines, and the adenomatous polyposis coli tumor suppressor protein (APC) was altered or missing in two others. In the APC-deficient cells, ectopic expression of wild-type APC eliminated the excess beta-catenin. Cells with stabilized beta-catenin contained a constitutive beta-catenin-Lef-1 complex. Thus, genetic defects that result in up-regulation of beta-catenin may play a role in melanoma progression.

Adenomatous Polyposis Coli Protein↗
PubMed1997

An audit of 267 consecutively excised mammographically detected breast lesions 1989-1993.

Pathology reports and slides were reviewed from 267 mammographically detected impalpable breast lesions, excised after hookwire localisation. There were 182 benign and 85 malignant lesions (benign to malignant ratio of 2.1:1). The invasive cancers tended to be small (mean 13 mm; 50% < or = 10 mm), of low histologic grade (38% Grade I), with a low incidence of lymph node metastases (15%). A high proportion of pure duct carcinoma in situ (DCIS) lesions (21%) was found, and an unusually high proportion of invasive lobular carcinoma (17%). Preoperative fine needle aspiration (FNA) was performed in 95 (36%) cases, including 47 (18%) sampled using sterotactic guidance and 48 (18%) sampled by palpation. The absolute sensitivity of diagnosis of malignancy was 32% and 5% respectively. In 79% of carcinomas further operation was performed, for axillary clearance or re-excision of incompletely excised tumor; this high rate was largely a result of a decision not to use frozen section diagnosis for impalpable lesions and because of the early stages of the development of preoperative needle diagnosis. 58% of invasive cancers, including seven of eight (87.5%) carcinomas with an extensive intraduct component (EIC + ve), and 72% of DCIS were incompletely excised at the first operation. Residual tumor was found in the re-excisions in 26% of EIC - ve invasive carcinomas, 71% of the EIC + ve cases and 56% of DCIS lesions. The malignant lesions had highly favourable prognostic indices. The need for concentration of experience with pre-operative FNA was highlighted. Positive excision margins were a good predictor for residual malignancy, particularly for EIC + ve cases and for DCIS lesions.

Adult↗