Failure to activate transcription factor NF-kappaB in corneal stromal cells (keratocytes)

PURPOSE

Freshly isolated cultures of corneal stromal cells (keratocytes) are incompetent to synthesize the tissue remodeling proteinase, collagenase, in response to agents such as cytochalasin B (CB) or phorbol myristate acetate (PMA), which are strong stimulators of collagenase expression in subcultured fibroblasts of all types, including those from corneal stroma. Incompetence is due to failure to activate an autocrine interleukin (IL)1alpha feedback loop required to mediate cell response. The goal of the present study was to investigate the mechanism for this failure.

METHODS

A cell culture model of freshly isolated corneal stromal cells and subcultured stromal fibroblasts from rabbits was used for these studies.

RESULTS

Competence to synthesize collagenase in response to CB was acquired as a differentiation property by corneal stromal cells placed in culture, and did not require subculture. Competence acquisition correlated with transition to a fibroblastic spindle shape, assembly of actin stress fibers, and the acquired capacity to collapse in response to CB. It was demonstrated that competence could be more precisely defined as the capacity to express IL-1alpha in response to IL-1, making possible activation of the feedback loop. Investigation into the signaling pathway for IL-1alpha expression in response to IL-1 revealed a requirement for reactive oxygen species and activity of the transcription factor nuclear factor (NF)kappaB. Importantly, freshly isolated stromal cells were found to be relatively incompetent to activate NF-kappaB in comparison to subcultured stromal fibroblasts.

CONCLUSIONS

Failure to activate NF-kappaB explains incompetence for expression of IL-1alpha in corneal stromal cells. Because NF-kappaB regulates many cell functions with potential to disturb corneal structure, including expression of inflammatory, stress, and degradative proteinase genes; protection against apoptosis; and cell replication; this seems likely to be an important mechanism protecting corneal stasis and preserving function.

Outcome of 350 implanted chest ports placed by interventional radiologists

PURPOSE

To determine the outcome of implanted chest ports placed by interventional radiologists.

MATERIALS AND METHODS

Between June 1993 and July 1996, a single institution placed 350 implanted chest ports in 346 patients by means of the subclavian vein approach. The medical records of these patients were reviewed to determine the outcome of the ports. Ports were implanted for chemotherapy (n = 341), blood transfusion (n = 7), or antibiotics (n = 2).

RESULTS

Immediate complications were seven (2%) pneumothoraces and one (0.3%) hematoma. Four (1.1%) of the pneumothoraces necessitated hospital admission and treatment with a chest tube. The remaining three were managed on an outpatient basis. One was successfully treated in the interventional suite by catheter suction. Two pneumothoraces were observed and resolved spontaneously. Mean time of patient follow-up was 260 days (range, 22-929 days). Total time of follow-up was 91,000 catheter days. Delayed complications were 10 cases of thrombosis (2.9% or 0.11 per 1,000 catheter days) of the subclavian vein, four infections (1.1% or 0.04 per 1,000 catheter days), four catheter coiling or tip malpositions (1.1% or 0.04 per 1,000 catheter days), three catheter occlusions (0.9% or 0.03 per 1,000 catheter days), and one catheter leak (0.3% or 0.01 per 1,000 catheter days). Six (1.7%) ports had to be removed as a result of a delayed complication.

CONCLUSION

Chest port implantation by interventional radiologists within the radiology department is a successful and safe procedure with complication rates equivalent to, or lower than, those reported in surgical placement series.

Scintigraphic demonstration of a right-to-left intracardiac shunt in a patient with massive pulmonary emboli

A case of massive pulmonary embolism resulting in marked pulmonary to systemic shunting in a patient with a previously clinically inapparent ventricular or atrial septal defect is presented. The various types of unrecognized intracardiac shunts and their prevalence in the adult population are discussed.

Percutaneous CT-guided biopsy of adrenal masses: immediate and delayed complications

OBJECTIVE

To determine the immediate and delayed complications of percutaneous adrenal biopsy and any relationship between biopsy methods and complications.

MATERIALS AND METHODS

Medical records and radiological examinations of 83 percutaneous adrenal biopsy were reviewed. Indication for biopsy, inpatient/outpatient status, lesion size and location, imaging modality used, needle type, size, approach and number of passes, biopsy results, immediate complications, and delayed complications were recorded.

RESULTS

Computed tomography was used in 79 cases (95%) and ultrasound in 4 (5%). The biopsy approach was posterior in 37 cases, transhepatic in 33, transpancreatic in 9, anterior in 2, transsplenic in 1, and lateral in 1. The total complication rate was 8.4% and was slightly higher for the transhepatic approach (12%) than the posterior approach (8%). Seven complications occurred: two pneumothoraces, two pain, one perinephric hemorrhage, one subcapsular and intrahepatic hematoma, and one hepatic needle-tract metastasis. The posterior approach was complicated by the two pneumothoraces and perinephric blood; the transhepatic was used in the other four. Five of the complications occurred with 22 gauge needles.

CONCLUSION

Percutaneous adrenal biopsy is a safe procedure. Complications occurred in 7 of our patients (8.4%).

The rabbit gene for 92-kDa matrix metalloproteinase. Role of AP1 and AP2 in cell type-specific transcription

We isolated the rabbit gene for the 92-kDa matrix metalloproteinase, gelatinase B, and sequenced 1802 contiguous bases covering the first three exons and 522 bases of DNA upstream of the start site for transcription. The DNA between bases -519 and +19 is sufficient to drive expression of a reporter gene in early passage cultures of corneal fibroblasts or primary cultures of corneal epithelial cells. Basal activity of the gelatinase B promoter in fibroblasts is lower than a collagenase promotor of 1800 base pairs, but activity of both promotors is similarly stimulated by treatment of transfected cells with phorbol 12-myristate 13-acetate, and stimulation is enhanced by co-treatment with transforming growth factor-beta. In contrast, basal activity of the gelatinase B promotor in epithelial cells is higher than the collagenase promotor. Deletion analysis demonstrated that sequences upstream of base -330 confer cell type-specific activity to the gelatinase B promotor. Site-directed mutagenesis revealed that an AP1-like element within this region is specifically utilized by fibroblasts. This region also contains elements that confer the capacity for activation by AP2, a transcription factor found to be expressed by corneal epithelial cells but not by corneal fibroblasts. In contrast, AP2 does not activate the collagenase promotor. These results provide a molecular basis for the unique cell type-specific expression pattern of gelatinase B as compared to other matrix metalloproteinases.