Gateable suppression of spin relaxation in semiconductors

The decay of spin memory in a 2D electron gas is found to be suppressed close to the metal-insulator transition. By dynamically probing the device using ultrafast spectroscopy, relaxation of optically excited electron spin is directly measured as a function of the carrier density. Motional narrowing favors spin preservation in the maximally scattered but nonlocalized electronic states. This implies that the spin-relaxation rate can be both tuned in situ and specifically engineered in appropriate device geometries.

Efficient generation of respiratory syncytial virus (RSV)-neutralizing human MoAbs via human peripheral blood lymphocyte (hu-PBL)-SCID mice and scFv phage display libraries

RSV is one of the major causes of pneumonia and bronchiolitis in infants and young children and is associated with high mortality. RSV neutralizing human antibody (hu-Ab) is known to mediate resistance to viral infection as well as to be an effective treatment for severe lower respiratory tract RSV infection. We have previously demonstrated that human primary and secondary immune responses can be established in severe combined immunodeficient mice engrafted with human peripheral blood lymphocytes (hu-PBL-SCID). By combining this animal model with the single-chain Fv antibody (scFv) phage display library technique, we were able to investigate further its clinical potential by generating a panel of human scFvs that exhibit both high F glycoprotein (RSV-F) binding affinities ( approximately 108 M(-1)) and strong neutralizing activities against RSV infection in vitro. Sequencing analysis of the randomly isolated anti-RSV-F scFv clones revealed that they were derived from different VH families with mutations in the complementarity-determining region 1 (CDR1). The results suggest that: (i) RSV-F-specific human immune responses and affinity maturation can be induced in hu-PBL-SCID mice; and (ii) this approach can be applied to generate large numbers of human scFvs with therapeutic potential. Despite the fact that hu-PBL-SCID mouse and human scFv phage display library have individually been established, our approach contributes a simple and significant step toward the generalization of antigen-specific human monoclonal antibody (hu-MoAb) production and their clinical applications.

Identification of differentially expressed genes in epithelial stem/progenitor cells of fetal rat liver

Differentially expressed cDNA clones from fetal rat liver were isolated using suppression subtractive hybridization, combined with an efficient screening strategy. Approximately 30,000 clones were screened, yielding 643 genes whose expression was induced, of which 201 clones were distinct and 68 represented ESTs or newly discovered genes of unknown function. Based on their expression patterns in different organs, fetal liver, liver regeneration models, and gut epithelial progenitor cell lines, the subtracted clones presented in this work were placed into four categories: (1) hepatoblast-specific genes; (2) hematopoietic cell-specific genes; (3) genes expressed in hepatoblasts, in hematopoietic cells, and at varying levels in other tissues; and (4) genes overexpressed in fetal liver, in models of activation of liver progenitor cells, and in epithelial progenitor cell lines. Hepatoblast-specific clones and those representing genes induced during liver regeneration are under further study to define their specific function(s) in liver cell growth control and/or differentiation.

Use of endovascular stents for the treatment of abdominal aortic aneurysm

The conventional open surgical repair of abdominal aortic aneurysms is a well-established and durable procedure. However, as with all other major abdominal surgical operations, there are associated morbidities. Both mortality and morbidity increase significantly with advanced patient age and associated comorbid conditions. Endovascular aortic stent-grafts offer a significantly less invasive alternative to conventional open-surgical repair. Patients previously considered unsuitable for open repair can often receive treatment for aneurysms with endovascular techniques. The US Food and Drug Administration has recently approved two endovascular stent-graft devices for use within the United States.

Proliferation and differentiation of fetal liver epithelial progenitor cells after transplantation into adult rat liver

To identify cells that have the ability to proliferate and differentiate into all epithelial components of the liver lobule, we isolated fetal liver epithelial cells (FLEC) from ED 14 Fischer (F) 344 rats and transplanted these cells in conjunction with two-thirds partial hepatectomy into the liver of normal and retrorsine (Rs) treated syngeneic dipeptidyl peptidase IV mutant (DPPIV(-)) F344 rats. Using dual label immunohistochemistry/in situ hybridization, three subpopulations of FLEC were identified: cells expressing both alpha-fetoprotein (AFP) and albumin, but not CK-19; cells expressing CK-19, but not AFP or albumin, and cells expressing AFP, albumin, and cytokeratins-19 (CK-19). Proliferation, differentiation, and expansion of transplanted FLEC differed significantly in the two models. In normal liver, 1 to 2 weeks after transplantation, mainly cells with a single phenotype, hepatocytic (expressing AFP and albumin) or bile ductular (expressing only CK-19), had proliferated. In Rs-treated rats, in which the proliferative capacity of endogenous hepatocytes is impaired, transplanted cells showed mainly a dual phenotype (expressing both AFP/albumin and CK-19). One month after transplantation, DPPIV(+) FLEC engrafted into the parenchyma exhibited an hepatocytic phenotype and generated new hepatic cord structures. FLEC, localized in the vicinity of bile ducts, exhibited a biliary epithelial phenotype and formed new bile duct structures or were incorporated into pre-existing bile ducts. In the absence of a proliferative stimulus, ED 14 FLEC did not proliferate or differentiate. Our results demonstrate that 14-day fetal liver contains lineage committed (unipotential) and uncommitted (bipotential) progenitor cells exerting different repopulating capacities, which are affected by the proliferative status of the recipient liver and the host site within the liver where the transplanted cells become engrafted. These findings have important implications in future studies directed toward liver repopulation and ex vivo gene therapy.

A comparison of EGF and MAb 528 labeled with 111In for imaging human breast cancer

Our objective was to compare 111In-labeled human epidermal growth factor (hEGF), a 53-amino acid peptide with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MAb) 528 (IgG2a) for imaging EGFR-positive breast cancer.

METHODS

hEGF and MAb 528 were derivatized with diethylenetriamine pentaacetic acid (DTPA) and labeled with 111In acetate. Receptor binding assays were conducted in vitro against MDA-MB-468 human breast cancer cells. Biodistribution and tumor imaging studies were conducted after intravenous injection of the radiopharmaceuticals in athymic mice bearing subcutaneous MCF-7, MDA-MB-231, or MDA-MB-468 human breast cancer xenografts or in severe combined immunodeficiency mice implanted with a breast cancer metastasis (JW-97 cells). MCF-7, MDA-MB-231, JW-97, and MDA-MB-468 cells expressed 1.5 x 10(4), 1.3 x 10(5), 2.7 x 10(5), and 1.3 x 106 EGFR/cell, respectively in vitro.

RESULTS

111In-DTPA-hEGF and 111In-DTPA-MAb 528 bound with high affinity to MDA-MB-468 cells (Ka of 7.5 x 10(8) and 1.2 x 10(8) L/mol, respectively). 111In-DTPA-hEGF was eliminated rapidly from the blood with < 0.2% injected dose/g (%ID/g) circulating at 72 h after injection, whereas 111In-DTPA-MAb 528 was cleared more slowly (3%ID/g in the blood at 72 h). Maximum localization of 111In-DTPA-hEGF in MDA-MB-468 tumors (2.2 %ID/g) was 10-fold lower than with 111In-DTPA-MAb 528 (21.6 %ID/g). There was high uptake in the liver and kidneys for both radiopharmaceuticals. Tumor-to-blood ratios were greater for 111In-labeled hEGF than for MAb 528 (12:1 versus 6:1), but all other tumor-to-normal tissue ratios were higher for MAb 528. MDA-MB-468 and JW-97 tumors were imaged successfully with both radiopharmaceuticals, but tumors were more easily visualized using 111In-labeled MAb 528. There was no direct quantitative relationship between EGFR expression on breast cancer cell lines in vitro, and tumor uptake of the radiopharmaceuticals in vivo, but control studies showed that tumor uptake was receptor mediated.

CONCLUSION

Our results suggest that the tumor uptake in vivo of receptor-binding radiopharmaceuticals is controlled to a greater extent by their elimination rate from the blood than by the level of receptor expression on the cancer cells. Radiolabeled anti-EGFR MAbs would be more effective for tumor imaging in cancer patients than peptide-based radiopharmaceuticals such as hEGF, because they exhibit higher tumor uptake at only moderately lower tumor-to-blood ratios.

Oral immunization of mice with transgenic tomato fruit expressing respiratory syncytial virus-F protein induces a systemic immune response

Respiratory syncytial virus (RSV) is one of the most important pathogens of infancy and early childhood. Here a fruit-based edible subunit vaccine against RSV was developed by expressing the RSV fusion (F) protein gene in transgenic tomato plants. The F-gene was expressed in ripening tomato fruit under the control of the fruit-specific E8 promoter. Oral immunization of mice with ripe transgenic tomato fruits led to the induction of both serum and mucosal RSV-F specific antibodies. The ratio of immunoglobulin subclasses produced in response to immunization suggested that a type 1 T-helper cell immune response was preferentially induced. Serum antibodies showed an increased titer when the immunized mice were exposed to inactivated RSV antigen.

111In-labeled EGF is selectively radiotoxic to human breast cancer cells overexpressing EGFR

Our objective was to determine whether the internalization and nuclear translocation of human epidermal growth factor (hEGF) after binding to its cell surface receptor (EGFR) could be exploited to deliver the Auger electron emitter 111In into EGFR-positive breast cancer cells for targeted radiotherapy.

METHODS

hEGF was derivatized with diethylenetriamine pentaacetic acid (DTPA) and radiolabeled with 111In-acetate. The internalization of 111In-DTPA-hEGF by MDA-MB-468 breast cancer cells (1.3x10(6) EGFRs/cell) was determined by displacement of surface-bound radioactivity by an acid wash. The radioactivity in the cell nucleus and chromatin, isolated by differential centrifugation, was measured. The effect on the growth rate of MDA-MB-468 or MCF-7 (1.5x10(4) EGFRs/cell) cells was determined after treatment in vitro with 111In-DTPA-hEGF, unlabeled DTPA-hEGF, or 111In-DTPA. The surviving fraction of MDA-MB-468 or MCF-7 cells treated in vitro with 111In-DTPA-hEGF was determined in a clonogenic assay. The radiotoxicity in vivo against normal hepatocytes or renal tubular cells was evaluated by measuring alanine aminotransferase (ALT) or creatinine levels in mice administered high amounts of 111In-DTPA-hEGF (equivalent to human doses up to 14,208 MBq) and by light and electron microscopy of the tissues.

RESULTS

Approximately 70% of 111In-DTPA-hEGF was internalized by MDA-MB-468 cells within 15 min at 37 degrees C and up to 15% was translocated to the nucleus within 24 h. Chromatin contained 10% of internalized radioactivity. The growth rate of MDA-MB-468 cells was decreased 3-fold by treatment with 111In-DTPA-hEGF (45-60 mBq/cell). Treatment with unlabeled DTPA-hEGF caused a 1.5-fold decrease in growth rate, whereas treatment with 111In-DTPA had no effect. Targeting of MDA-MB-468 cells with up to 130 mBq/cell of 111In-DTPA-hEGF resulted in a 2-logarithm decrease in their surviving fraction. No decrease in the growth rate or surviving fraction of MCF-7 cells was evident. There was no evidence of hepatotoxicity or renal toxicity in mice administered high amounts of 111In-DTPA-hEGF. Radiation dosimetry estimates suggest that the radiation dose to an MDA-MB-468 cell targeted with 111In-DTPA-hEGF could be as high as 25 Gy with up to 19 Gy delivered to the cell nucleus.

CONCLUSION

111In-DTPA-hEGF is a promising novel radiopharmaceutical for targeted Auger electron radiotherapy of advanced, hormone-resistant breast cancer.

Primary Gianturco stent placement for inferior vena cava abnormalities following liver transplantation

PURPOSE

To determine the efficacy of primary Gianturco stent placement for patients with inferior vena caval (IVC) abnormalities following liver transplantation.

MATERIALS AND METHODS

From August 1996 through March 1999, nine adult patients developed significant IVC abnormalities following liver transplantation. Patients were referred for vena cavography on the basis of abnormal clinical findings, laboratory values, liver biopsy results, Doppler findings, or a combination. Those patients demonstrating a significant caval or hepatic venous gradient were treated with primary Gianturco stent placement. Patients were followed clinically (nine patients), with duplex ultrasound (nine patients), vena cavography (four patients), and biopsy (seven patients).

RESULTS

Original pressure gradients ranged from 3 to 14 mm Hg, with a mean of 9 mm Hg. Gradients were reduced to 3 mm Hg or less in all nine patients; presenting signs and symptoms either resolved or improved in eight of nine patients. The ninth patient required repeated transplantation 2 days later. A second patient died 433 days after stent placement of recurrent hepatitis C. Another initially improved following caval stent placement, but underwent repeated transplantation 7 days later due to hepatic necrosis from hepatic arterial thrombosis. Follow-up for the remaining six patients has averaged 491 days, with no clinical, venographic, or ultrasound evidence for recurrent caval stenosis.

CONCLUSIONS

Intermediate term results suggest that primary Gianturco stent placement for IVC stenosis, compression, or torsion resulting after liver transplantation is safe and effective.

Human serum induces apoptosis of xenogenic cardiomyocytes in vivo and in vitro

Discordant xenotransplantation is complicated by delayed xenograft rejection (DXR). Previous studies have demonstrated that anti-apoptotic genes are protective against DXR. This study examines the hypothesis that apoptosis plays a role in human anti-xenograft responses. C57BL/6 mice and NOD SCID mice were given a single intravenous injection of either a lethal dose (LD, survival < 30 min) or a sublethal dose (SLD) of human serum, and isolated pig and mouse rod-shaped cardiomyocytes were exposed to human serum in vitro. In situ detection of apoptotic cells in mouse hearts was assessed using a terminal deoxynucleotidyl transferase-mediated dUTP nicked-end labeling assay. Mice transfused with human serum had approximately a 10-fold increased percentage of apoptotic cells after SLD 18 h post-injection compared with animals given saline, and a fourfold increase over LD. Administration of cobra venom factor (CVF) decomplemented SLD 18 h did not significantly (P > 0.05) alter the percentage apoptosis. The addition of 20 mM Gal-alpha-1,3-Gal to SLD 18 h significantly (P < 0.05) reduced percentage apoptosis to levels comparable to saline treated control animals. In vitro using mouse and pig cardiomyocytes demonstrated parallel results as in vivo experiments. Human serum induces apoptosis of cardiomyocytes in immunocompetent and immunoincompetent mice in vivo, as well as mouse and pig cardiomyocytes in vitro. Further, this apoptotic response can be inhibited by the addition of Gal-alpha-1,3-Gal without affecting the capacity of the serum to cause HAR. These results demonstrate that a putative human serum factor induces a delayed apoptotic injury of xenograft tissues, and supports the hypothesis that apoptosis may be an important mediator of DXR.

Non-traumatic rhabdomyolysis with acute renal failure

A clinical profile of non-traumatic rhabdomyolysis with acute renal failure is presented. Myoglobinuric renal failure is treatable and hence a high index of suspicion is warranted in the etiologies discussed.

Shiga-like toxin-1 receptor on human breast cancer, lymphoma, and myeloma and absence from CD34(+) hematopoietic stem cells: implications for ex vivo tumor purging and autologous stem cell transplantation

The ribosome-inactivating protein, Shiga-like toxin-1 (SLT-1), targets cells that express the glycolipid globotriaosylceramide (CD77) on their surface. CD77 and/or SLT-1 binding was detected by flow cytometry and immunocytochemistry on lymphoma and breast cancer cells recovered from biopsies of primary human cancers as well as on B cells or plasma cells present in blood/bone marrow samples of multiple myeloma patients. Breast cancer cell lines also expressed receptors for the toxin and were sensitive to SLT-1. Treatment of primary B lymphoma, B-cell chronic lymphocytic leukemia, and myeloma B or plasma cells with SLT-1-depleted malignant B cells by 3- to 28-fold, as measured by flow cytometry. Depletion of myeloma plasma cells was confirmed using a cellular limiting dilution assay followed by reverse transcriptase-polymerase chain reaction analysis of clonotypic IgH transcripts, which showed a greater than 3 log reduction in clonotypic myeloma cells after SLT-1 treatment. Receptors for the toxin were not detected on human CD34(+) hematopoietic progenitor cells (HPC). HPC were pretreated with a concentration of SLT-1 known to purge primary malignant B cells and cultured for 6 days. The number of HPC was comparable in toxin-treated and untreated cultures. HPC were functionally intact as well. Colony-forming units (CFU) were present at an identical frequency in untreated and SLT-1 pretreated cultures, confirming that CFU escape SLT-1 toxicity. The results suggest the ex vivo use of SLT-1 in purging SLT-1 receptor-expressing malignant cells from autologous stem cell grafts of breast cancer, lymphoma, and myeloma patients.

Resource requirements for interventional radiologic management of long-term ambulatory hemodialysis patients

OBJECTIVE

The purpose of this study was to determine how many and what type of procedures a vascular and interventional radiology service should provide for patients at ambulatory-patient dialysis centers and to determine the necessary resource requirements. These data may provide a realistic starting point for those engaged in the planning and provision of contractual services to dialysis centers.

MATERIALS AND METHODS

Patient records at three dialysis centers for a recent 3-year period were examined, and demographic and clinical data were recorded. Records were cross-correlated with records from the vascular and interventional radiology service that had contractually provided all dialysis-related procedures. These data generated a monthly procedure volume and case mix per 100 dialysis patients. Facility usage times for 121 dialysis-related procedures were obtained prospectively and used to calculate the expected resources needed to service the dialysis patients.

RESULTS

The three centers provided 5795 hemodialysis-months to 386 patients. Of the 386 patients over the 36-month period, 101 died and 92 transferred from the centers. Three hundred and sixteen patients required 1580 interventional procedures. Monthly procedure volume per 100 dialysis patients averaged 27.1 procedures. Observed procedure times were used to calculate expected room-time hours required to service the monthly procedural volume and case mix per 100 dialysis patients.

CONCLUSION

On average, 500 ambulatory dialysis patients will require the full-time use of an interventional suite and the services of a full-time technologist, nurse, and physician to provide necessary dialysis-related procedures. If resources cannot accommodate this volume, the quality and timeliness of care for these patients is jeopardized.

Intradermal injection of autologous dermal fibroblasts improves wound healing in irradiated skin

BACKGROUND

Despite its well-recognized benefits in the management of several solid tumors, the use of radiotherapy prior to surgery is associated with a high incidence of significant surgical wound healing complications. Radiation-induced damage to dermal fibroblasts has been proposed as an important cause. We hypothesized that the introduction of normal, unirradiated fibroblasts into previously irradiated skin would enhance healing of the subsequent surgical wound.

MATERIALS AND METHODS

Four groups of wounds were examined in female Wistar rats: (1) unirradiated skin (n = 10), (2) irradiated skin injected with tissue culture medium alone (n = 17), (3) irradiated skin injected with autologous dermal fibroblasts (n = 17), and (4) irradiated skin injected with irradiated autologous dermal fibroblasts (n = 7). Wounds were evaluated biomechanically and histologically.

RESULTS

The biomechanical values of breaking load, ultimate tensile strength, elastic modulus, and toughness were significantly greater in the irradiated wounds injected with fibroblasts than those injected with medium only. These cell-injected wounds did not perform as well biomechanically as those in unirradiated skin. Irradiating the cells prior to injection resulted in biomechanical results no better than those in medium-injected wounds.

CONCLUSIONS

These results demonstrate that injection of normal, unirradiated fibroblasts significantly improves healing of the irradiated surgical wound. These cells are likely better able to respond to the proliferative, migratory, and synthetic demands of the wound healing environment, as injection of irradiated cells has an equivalent effect on healing as injection of medium alone.

Hepatitis C prevalence and risk factors in the northern Alberta dialysis population

Hepatitis C virus (HCV) is an emerging global public health issue with particular relevance in multiply transfused renal dialysis patients. This cross-sectional study evaluated the prevalence and risk factors for HCV infection among renal dialysis patients in northern Alberta, Canada. Ninety-two percent of eligible patients (n = 336) provided informed consent to participate. Participants were interviewed to gather risk factor information and, using multiple logistic regression analysis with exact inference, a predictive model for HCV infection in this population was developed. The prevalence of HCV infection in the population was 6.5%, and all positive patients had at least one identifiable risk factor. The multivariate analysis showed that the risk of HCV infection was greater for those in the 18-55 years age category (odds ratio (OR) = 4.9, 95% confidence interval (CI) 1.2-27.9), patients who had been on dialysis > 5 years (OR = 3.7, 95% CI 1.2-12.0), and patients who had > or = 2 high risk life-style behaviors (OR = 5.0, 95% CI 1.5-16.7). Transfusion prior to 1990 was marginally associated with HCV status (OR = 4.0, 95% CI 0.96-16.3). This study documented previously unreported life-style risk factors for HCV infection in patients with renal failure, confirmed the expected decline in transfusion-acquired HCV infection in this population, and provided evidence against nosocomial transmission of HCV.

Intrahepatic arterioportal fistula: gadolinium-enhanced 3D magnetic resonance angiography findings and angiographic embolization with steel coils

We describe a case of a 59-year-old patient with intrahepatic arterioportal fistula secondary to blunt trauma sustained by a motor vehicle accident 36 years earlier. The fistula was demonstrated 36 years after the accident in a clinical work-up for diarrhea of 1 month's duration, using contrast enhanced three-dimensional breath-hold MRA. A communication between the dilated portal vein and dilated hepatic artery was shown at the level of distal branches. After subsequent demonstration by conventional angiography, the fistula was embolized using steel coils. Following the therapeutic intervention, the patient's diarrhea ceased.

Effect of interleukin-6 secreted by engineered human stromal cells on osteoclasts in human bone

The effect of elevated human IL-6 (hIL-6) production by human bone marrow (Hu-BM) stromal cells on osteoclasts in human bone was examined. Human bone was implanted into nonobese diabetic mice with severe combined immunodeficiency (Hu-Bone-NOD/SCID mice). Immunohistochemistry of bone implants and mouse spleens (at 20 weeks), showed human CD45+ cells, B cells, and macrophages in both tissues. Thus, Hu-BM cells survive human bone transplantation and infiltrate mouse tissue. Bone implants had 75 +/- 12% (mean +/- SD) human CD45+ cells, and 9 +/- 4% mouse hematopoietic cells. A retrovirus vector containing the human IL-6 gene was used to transduce Hu-BM stromal cells (IL-6/stromal) and the PA317 cell line (IL-6/PA317). IL-6/ stromal cells (secreting, on average, 17 microg of hIL-6/10(6) cells per 24 h) were injected directly into human bone implants in Hu-Bone-NOD/SCID mice. IL-6/PA317 cells (secreting 16 microg/mL of hIL-6/10(6) cells per 24 h) were injected intraperitoneally into Hu-Bone-NOD/SCID mice. Analyses of sera from both groups of animals showed elevated levels of IL-6. However, only bone implants engrafted with IL-6/stromal cells had a statistically significant increase in osteoclast-lined mineralized trabecular bone surface (BS). Thus, a high concentration of serum hIL-6 in Hu-Bone-NOD/SCID mice alone does not increase osteoclast-lined BS in bone implants. Most importantly, it is the type of human BM cell that secretes the high levels of hIL-6 that is most critical.

Substance P fragments and striatal endogenous dopamine outflow: interaction with substance P

Accumulating evidence shows that N- and C-terminal substance P fragments have significant biological activity. Substance P(1-9) and substance P(6-11) have been reported to be major substance P metabolites in rat striatum. We investigated the effects of these fragments on endogenous dopamine outflow in rat striatal slices. Substance P-(1-9) and substance P-(6-11) induced a significant increase in dopamine outflow at 0.1 and 1 nM. The effects of substance P-(6-11) (1 nM) were reversed by the tachykinin NK1 antagonist WIN 51,708 (17beta-hydroxy-17alpha-ethynyl-5alpha-androstano[3,2- b]pyrimido[1,2-a]benzimidazole) (2.5 nM), whereas the effects of substance P-(1-9) were not modified by the antagonist. Substance P-(1-9) and substance P-(6-11) (1 nM) did not increase the dopamine overflow induced by 25 mM KCI. The effects of the two fragments were reversed by the muscarinic antagonist atropine (1 microM) but not by nicotinic antagonists dihydro-beta-erythroidine (0.5 microM) and pempidine (10 microM). The co-incubation of tissue with substance P and each fragment in a 1/1 or 10/1 ratio of substance P to metabolite revealed a negative interaction between parent and fragments. A similar pattern was observed when substance P was co-administered with the active fragments substance P(1-4), substance P(1-7), substance P(5-11) and substance P(8-11). The data show that substance P-(1-9) and substance P-(6-11) have modulatory effects similar to substance P. However, the presence of active substance P metabolites does not appear to amplify the signal mediated by the parent peptide.

The role of T cells in polyethylene particulate induced inflammation

OBJECTIVE

To investigate the role of T lymphocytes in ultra-high molecular weight polyethylene (UHMWPE) induced inflammation in joint arthroplasty.

METHOD

We address the role of T cells in wear induced inflammation by injecting the knee joints of both immune competent rats and mice and severe combined immunodeficient (SCID) mice with UHMWPE. Histological and immunohistochemical analysis of the synovial tissues was compared. Interaction between human T cells and UHMWPE particles was examined in vitro using T cell activation assays.

RESULTS

Histological and immunohistochemical analysis of the knees of the immune competent animals showed significant UHMWPE induced inflammation. In contrast, the tissue in the SCID mice knee joints showed very little inflammatory response to UHMWPE despite phagocytosis of the particulate. Since the SCID mice have no functional T or B lymphocytes, it is highly likely that the lack of inflammation in knee joints may be due to the absence of mouse T cells, as the infiltration of T cells into the joint tissue may enhance the inflammatory response to UHMWPE particles. T cell activation assays showed that T cells were not directly activated by UHMWPE particles and the nature of the interaction was not revealed from these experiments.

CONCLUSIONS

Although T cells are not directly involved in UHMWPE particle induced inflammation, as shown by the T cell activation assays, the histological data from the mice studies clearly show differences in the amplitude of inflammation from animals with and without functional T cells. Our studies suggest that the T cells may enhance the inflammatory response due to a bystander effect. Since the macrophages upon ingestion of UHMWPE particles release several cytokines including tumor necrosis factor-alpha, interleukin 1, and IL-6, it is possible that T cells in the vicinity of these macrophages may become attracted to the knee joint and activated due to cytokine release.

A/T-rich sequences act as quantitative enhancers of gene expression in transgenic tobacco and potato plants

The role of an A/T-rich positive regulatory region (P268, -444 to -177 from the translation start site) of the pea plastocyanin gene (PetE) promoter has been investigated in transgenic plants containing chimeric promoters fused to the beta-glucuronidase (GUS) reporter gene. This region enhanced GUS expression in leaves of transgenic tobacco plants when fused in either orientation to a minimal pea PetE promoter (-176 to +4) and in roots when fused in either orientation upstream or downstream of a minimal cauliflower mosaic virus 35S promoter (-90 to +5). The region was also able to enhance GUS expression in microtubers of transgenic potato plants when placed in either orientation upstream of a minimal class I patatin promoter (-332 to +14). Dissection of P268 revealed that cis elements responsible for enhancing GUS expression from the minimal PetE promoter were distributed throughout P268. Multiple copies of a 31 bp A/T-rich sequence from within P268 and of a 26 bp random A/T sequence were able to enhance GUS expression from the minimal PetE promoter, indicating that A/T-rich sequences are able to act as quantitative, non-tissue-specific enhancer elements in higher plants.

Bronchial artery embolization for the treatment of hemoptysis in patients with cystic fibrosis

Hemoptysis is common in patients with cystic fibrosis (CF). Bleeding may vary in severity, ranging from minor blood-streaking of sputum to expectoration of significant quantities of blood. Major hemoptysis, defined as bleeding greater than 240 ml/24 h, represents a medical emergency. Bronchial artery embolization (BAE) is one of the treatment options for hemoptysis. We reviewed the 10-yr experience at the University of North Carolina Hospitals in the treatment of hemoptysis by BAE. Eighteen patients with CF were hospitalized on 29 occasions and underwent 36 BAE procedures for the control of hemoptysis. Most patients (n = 11) had very severe lung disease (FEV1 < 35%) with a high incidence (n = 9, 50%) of multi-drug-resistant bacteria. Fifteen patients (n = 33 procedures) were followed for a mean of approximately 22 mo after BAE. The overall efficacy of BAE for initial control of hemoptysis was 75% (n = 22) after one session, 89% (n = 26) after two sessions, and 93% (n = 27) after three sessions. The overall recurrence rate per episode was 46% (12/26 presentations in four patients) with a mean time for recurrence of approximately 12 mo. There was a high incidence (75%) of bleeding from nonbronchial systemic collateral vessels among patients (n = 7) who had undergone a previous BAE. There were two deaths associated with massive hemoptysis despite BAE. Three patients had transient neurologic deficits during BAE. We concluded that BAE is a relatively safe and effective means of treating significant hemoptysis in patients with CF.