Spatial relationships in early signaling events of flow-mediated endothelial mechanotransduction.

Blood flow interactions with the vascular endothelium represent a specialized example of mechanical regulation of cell function that has important physiological and pathological cardiovascular consequences. The endothelial monolayer in vivo acts as a signal transduction interface for forces associated with flowing blood (hemodynamic forces) in the acute regulation of artery tone and chronic structural remodeling of arteries, including the pathology of atherosclerosis. Mechanisms related to spatial relationships at the cell surfaces and throughout the cell that influence flow-mediated endothelial mechanotransduction are discussed. In particular, flow-mediated ion channel activation and cytoskeletal dynamics are considered in relation to topographic analyses of the luminal and abluminal surfaces of living endothelial cells.

Potential vascular damage from radiation in the space environment.

Cultured endothelial cells of blood vessels have a Do of 2 Gy for X-rays. A dose of 0.5 Gy of X-rays has an acute effect on vessel diameter. The vessels may show other acute effects such as change in permeability including a change in the blood brain barrier. Changes occurring from late effects of chronic exposure in vascular architecture include telangiectasia and decrease in vascular density. Changes in the perivascular connective tissue particularly collagen may play a role in these changes. After charged particle exposure of 15 and 30 Gy, radiation changes in the blood brain barrier and vascular changes are noted in the nervous system. These long term changes are recorded by PET, MRI, and CT imaging. Chronic exposure to alpha particles causes vascular damage in compact bone resulting in bone infarcts. Using tandem scanning confocal microscopy in-situ imaging of the capillaries and collagen of the papillary dermis provides a non-invasive method of serial recording of changes in irradiated microvasculature.

Cancer following radiotherapy for peptic ulcer.

BACKGROUND: Radiotherapy for peptic ulcer was used between 1937 and 1965 to control excessive gastric acid secretions (mean dose, 14.8 Gy). Patients with this benign condition live many years after treatment and are at risk for late effects. PURPOSE: Our purpose was to investigate the risk of death from cancer following radiotherapy for peptic ulcer. METHODS: A mortality study was conducted of 3609 patients with peptic ulcer; 1831 were treated with radiation and 1778 were treated by other means. Extensive methods were used to trace patients. Radiation doses to specific organs were reconstructed from the original radiotherapy records. RESULTS: Nearly 70% of patients were found to have died. The average period of observation was 21.5 years (maximum 51 years). Compared with the general population, patients treated with or without radiation were at significantly increased risk of dying of cancer and non-malignant diseases of the digestive system. Risk of death due to heart disease was slightly higher following radiotherapy. Cancers of the stomach, pancreas, lung, and prostate were increased in both irradiated and nonirradiated patients. Radiotherapy was linked to significantly high relative risks (RRs) for all cancers combined (RR = 1.53; 95% confidence interval [CI] = 1.3-1.8), for cancers of the stomach (RR = 2.77; 95% CI = 1.6-4.8), pancreas (RR = 1.87; 95% CI = 1.0-3.4), and lung (RR = 1.70; 95% CI = 1.2-2.4), and for leukemia (RR = 3.28; 95% CI = 1.0-10.6). Radiation combined with surgery, or given to treat gastric ulcer, appeared to increase the risk of stomach cancer 10-fold, which was greater than the sum of individual effects. Patients with gastric ulcers were at higher risk for stomach cancer than patients with duodenal ulcers. CONCLUSIONS: Patients with peptic ulcer are at increased risk of dying of cancer, related in part to lifestyle factors and treatment. Radiotherapy and surgery together appear to induce carcinogenic processes that greatly enhance the development of stomach cancer. The risk of radiation-induced stomach cancer was 0.25 extra deaths per 10,000 persons per year per Gy, somewhat lower than reported in other studies. High-dose radiation may have increased the risk of pancreatic cancer, a condition rarely found elevated in irradiated populations, but misclassified death notices may have contributed to the excess. Cancer mortality remained high for up to 50 years, indicating that radiation damage may persist to the end of life.

Quantitative studies of endothelial cell adhesion. Directional remodeling of focal adhesion sites in response to flow forces.

Focal adhesion sites were observed in cultured endothelial cells by tandem scanning confocal microscopy and digitized image analysis, techniques that provide real-time images of adhesion site area and topography in living cells. Image subtraction demonstrated that in the presence of unidirectional steady laminar flow (shear stress [tau] = 10 dyn/cm2) a substantial fraction of focal adhesion sites remodeled in the direction of flow. In contrast, focal adhesions of control (no flow) cells remodeled without preferred direction. In confluent monolayers subjected to shear stresses of 10 dyn/cm2, cells began to realign in the direction of flow after 7-9 h. This was accompanied by redistribution of intracellular stress fibers, alignment of individual focal adhesion sites, and the coalescence of smaller sites resulting in fewer, but larger, focal adhesions per cell. Cell adhesion, repeatedly calculated in the same cells as a function of the areas of focal contact and the separation distances between membrane and substratum, varied by < 10% during both short (30 min), or prolonged (< or = 24 h), periods of exposure to flow. Consistent with these measurements, the gains and losses of focal adhesion area as each site remodeled were approximately equivalent. When the glass substratum was coated with gelatin, rates of remodeling were inhibited by 47% during flow (tau = 10 dyn/cm2). These studies: (a) reveal the dynamic nature of focal adhesion; (b) demonstrate that these sites at the ablumenal endothelial membrane are both acutely and chronically responsive to frictional shear stress forces applied to the opposite (lumenal) cell surface; and (c) suggest that components of the focal adhesion complex may be mechanically responsive elements coupled to the cytoskeleton.

Endothelial cell adhesion in real time. Measurements in vitro by tandem scanning confocal image analysis.

Real time measurements of cell-substratum adhesion in endothelial cells were obtained by tandem scanning confocal microscopy of sites of focal contact (focal adhesions) at the abluminal cell surface. Focal contact sites were sharply defined (low radiance levels) in the living cell such that the images could be enhanced, digitized, and isolated from other cellular detail. Sites of focal contact are the principal determinant of cell-substratum adhesion. Measurements of (a) the focal contact area and (b) the closeness of contact (inverse radiance) were used to nominally define the adhesion of a single cell or field of cells, and to record spontaneous and induced changes of cell adhesion in real time. The topography of focal contacts was estimated by calculating separation distances from radiance values using a calibration technique based on interference ring optics. While slightly closer contact was noted between the cell membrane and substratum at or near the center of each focal contact, separation distances throughout the adhesion regions were always < 50 nm. Subtraction of consecutive images revealed continuous spontaneous remodeling of individual focal adhesions in unperturbed cells during periods of < 1 min. Despite extensive remodeling of focal contact sites, however, cell adhesion calculated for an entire cell over extended periods varied by < 10%. When cytoskeletal stability was impaired by exposure to cytochalasin or when cells were exposed to proteolytic enzyme, endothelial adhesion declined rapidly. Such changes were recorded at the level of single cells, groups of cells, and at single focal adhesions. In both unperturbed and manipulated cells, the dynamics of remodeling and cell adhesion characteristics varied greatly between individual sites within the same cell; disappearance of existing sites and appearance of new ones often occurred within minutes while adjacent sites underwent minimal remodelling. Tandem scanning confocal microscopy image analysis of living cells in real time provides repetitive spatial, temporal, and quantitative information about cell adhesion. Such an approach should allow more precise quantitative analyses to be made of the interactions between extracellular matrix, adhesion proteins, integrins, and the cytoskeleton in the living cell.

Hemodynamic forces and vascular cell communication in arteries.

As the interface between the blood and the rest of the vessel wall, the endothelium is directly affected by hemodynamic shear stress (frictional) forces that locally regulate vascular tone and are implicated in the localization of atherosclerosis. There are many diverse responses of endothelial cells to hemodynamically related mechanical stresses ranging from ion channel activation to gene regulatory events. The processes of force transmission from the blood to the cell, and force transduction within the endothelium to electrophysiologic, biochemical, and transcriptional responses are poorly understood. This article reviews the principal mechanisms currently thought to be involved and outlines the signal pathways from the endothelium to underlying smooth-muscle cells.

Radiation therapy for pathologic stage III Hodgkin's disease with and without chemotherapy.

Ninety-eight patients with pathological Stage (PS) III Hodgkin's disease treated between 1969 and 1984 were retrospectively analyzed. Treatment consisted of radiation therapy (RT) alone in 46 patients and combined radiation therapy and chemotherapy (CMT) in 52 patients. The median follow-up was 10 years (range 3-19 years). Fifteen-year year survival for patients with Stage III1-is better than for Stage III2 patients (82% vs 53%; p = .014). Patients with Stage III1A have a favorable prognosis regardless of treatment modality. The probability of freedom from relapse at 15 years for patients with pathological Stage III1A treated with radiation therapy is 70%, compared to 83% for pathological Stage III1A patients treated with combined modality therapy (p = .56). In patients with pathological Stage III2A, III1B, and III2B relapses were less frequent with the use of combined modality therapy compared to radiation therapy. We conclude that pathological Stage III1A patients may be treated with radiation therapy alone; the other subsets of patients benefit from combined radiation and chemotherapy.

Combined modality therapy for tumor stage mycosis fungoides: results of a 10-year follow-up.

Twenty-one patients with tumor stage mycosis fungoides (MF) with or without lymph node (LN) involvement, were treated with total skin electron beam irradiation (TSEB) followed by six monthly cycles of systemic chemotherapy (CT) of either mechlorethamine (HN2) or cyclophosphamide (CTX) with vincristine (VCR), procarbazine, and prednisone (PRD) (COPP or MOPP). All patients had complete clearing of the skin after TSEB. However, while receiving chemotherapy, two patients developed visceral involvement and eight patients relapsed with limited cutaneous plaques (LCP). The median duration of remission was 12 months from the completion of TSEB, and all patients relapsed with cutaneous plaques within 25 months. Complete remission was again achieved using additional electron irradiation and maintenance therapy in all but one patient. Multiple cutaneous recurrences occurred in all patients. Median survival from the initiation of TSEB is 6 years. Five patients are living beyond 8 years (four off treatment without disease for 1 to 7 years). LN involvement did not influence initial response or survival. Combined modality therapy for tumor stage MF using TSEB followed by systemic CT and subsequent maintenance therapy may lead eventually to prolonged disease-free survival (DFS) in selected patients.

Treatment of pulmonary mycosis fungoides with whole-lung radiation therapy.

Visceral involvement is a relatively common but poorly appreciated occurrence in patients with mycosis fungoides. The lungs are the most common site of visceral involvement. Here we present two cases of mycosis fungoides with pulmonary parenchymal involvement, one of them proven by biopsy. Both patients were treated with whole-lung radiation therapy, with complete disappearance of the lesions and improvement of respiratory symptoms. There was no significant radiation-induced pulmonary toxicity. One patient continues to be alive with no recurrence in the lungs 17 months after radiation therapy.

Randomized neutron dose searching study for malignant gliomas of the brain: results of an RTOG study. Radiation Therapy Oncology Group.

From September 1980 through January 1985, the Radiation Therapy Oncology Group (RTOG) conducted a randomized, dose-searching study testing the efficacy of a concomitant neutron boost along with whole brain photon irradiation in the treatment of malignant gliomas of the brain. Patients had to have biopsy-proven, supratentorial, anaplastic astrocytoma or glioblastoma multiforme (Nelson schema) to be eligible for the study. The whole brain photon irradiation was given at 1.5 Gy per treatment, 5 days-a-week to a total dose of 45 Gy. Two days-a-week the patients were to receive neutron boost irradiation to the tumor volume as determined on CT scans. The neutron irradiation was to be given prior to and within 3 hours of the photon irradiation on that day. The rationale for this particular treatment regime is discussed. A total of 190 evaluable patients were randomized among 6 different neutron dose levels: 3.6, 4.2, 4.8, 5.2, 5.6 and 6.0 Gyn gamma. There was no difference in overall survival among the 6 different dose levels, but for patients having less aggressive tumor histology (anaplastic astrocytoma), there was a suggestion that patients on the higher dose levels had poorer overall survival than patients on the lower dose levels and also did worse than historical photon controls. Important prognostic factors were identified using a Cox stepwise regression analysis. Tumor histology, Karnofsky performance status, and patient age were found to be related to survival while extent of surgery and neutron dose had no significant impact. Autopsies were performed on 35 patients and the results correlated with the actual neutron dose as determined by central-axis isodose calculations. At all dose levels there were some patients with both radiation damage to normal brain tissue and evidence of viable tumor. No evidence was found for a therapeutic window using this particular treatment regimen.

Pleural involvement in stage IIIM0 non-small-cell bronchogenic carcinoma. A need to differentiate subtypes.

Forty-one patients with two subtypes of stage IIIM0 non-small-cell lung cancer treated over a 7-year period were evaluated. The first group of 20 patients had ipsilateral parietal pleural involvement not contiguous with the primary tumor but no distant metastases. Fifteen had positive pleural fluid cytology, seven with positive pleural biopsy in addition; four had extensive pleural studding or a positive biopsy but no effusion; and one had negative pleural fluid cytology. Treatment consisted of radiation therapy followed by combination chemotherapy in all. Due to symptoms, eight patients first had fluid drainage with or without sclerosis and two patients had a pleurectomy. Nine had progressive pleural disease despite the local treatment. To all modalities of therapy, only two patients had a partial response. One patient who had a pleurectomy lived 25 months. Median survival was 6.9 months. Cause of failure involved local progression in 17 patients. There was no difference in median survival by age, sex, histology, side of effusion, location of nodal disease, or use of local therapy. The second group of 21 patients had localized involvement of the parietal pleura by the primary tumor. There was deeper chest wall invasion in nine. All patients were rendered free of known disease by surgical resection, were stage T3N0-2M0, and received radiation and chemotherapy in addition to resection. The median survival was 13.5 months. There was local recurrence in nine patients but only one developed an effusion. Five patients were alive at 29-82 months. No variable unfavorably influenced survival except a central versus peripheral primary. Thus, the median survival of the patients in the first group with multiple sites of pleural involvement was similar to that of patients with distant metastases but with the cause of failure primarily local progression. In the majority of patients in the second group, parietal pleural and chest wall involvement, even with nodal metastases, did not translate into local failure, and long-term survival was possible.

Treatment of malignant gliomas with neutron radiation.

The author contends that neutron radiation therapy coupled with radiation therapy or other forms of particle radiation therapy may play a role in the management of malignant gliomas. Improved survival, particularly for the patients with the diagnosis of glioblastoma, is discussed.

Long-term survival of patients with localized diffuse histiocytic lymphoma.

From January 1970 to March 1981, localized diffuse histiocytic lymphoma (DHL) was identified in 31 patients by exploratory laparotomy and splenectomy (pathologic stage I, 17 patients; pathologic stage II, 14 patients) at the University of Chicago. The median follow-up time was 72 months. All patients were previously untreated and received radiation therapy as their primary treatment modality. Chemotherapy was administered only at the time of relapse. All but two patients achieved a complete remission (CR) with radiation therapy. The actuarial disease-free survival for patients with stage I disease is 94% at 5 years and 72% at 10 years. For stage II disease, the disease-free survival is 56% at 5 years and 31% at 10 years. The difference in the disease-free survival between stage I and II is statistically significant (P = .02). The survival at 10 years is 70% for stage I disease and 46% for stage II disease. Five patients had documented relapses (four had stage II disease). Only two of those who relapsed achieved a second CR with salvage chemotherapy. Our data show an excellent outcome in patients with pathologic stage I disease, indicating that a high percentage of these cases can be cured with radiotherapy alone. Patients with clinical stage II disease might be served better with chemotherapy.

Sarcomas arising after radiotherapy for peptic ulcer disease.

Therapeutic gastric irradiation has been used to reduce peptic juice secretion in patients with peptic ulcer disease. Between 1937 and 1968 a total of 2049 patients received such therapy at the University of Chicago. Three of these patients are known to have developed sarcomas in the field of radiation. Two gastric leiomyosarcomas of the stomach were diagnosed 26 and 14 years after treatment and a malignant fibrous histiocytoma of the anterior chest wall was removed six years after gastric irradiation. Of 743 peptic ulcer patients treated without irradiation and constituted as a control group for the study of therapeutic gastric radiation, none is known to have developed sarcoma. As the incidence of sarcoma in these patient groups is known only from the tumor registry of the University of Chicago, other cases of sarcoma may exist in the groups. While an increased incidence of sarcoma has not been proven to occur in patients who received therapeutic gastric irradiation for peptic ulcer disease, the possibility of such a risk should be borne in mind by physicians caring for such patients.

Pathologic stages IA and IIA Hodgkin's disease: results of treatment with radiotherapy alone (1968-1980).

Between Jan 1, 1968, and Dec 31, 1980, 108 previously untreated patients with Hodgkin's disease pathologic stages (PSs) IA (29 patients) and IIA (79 patients) initially received radiotherapy alone. One postoperative death (due to pulmonary embolus) (0.9%) occurred, with one serious complication (0.9%). Between 1968 and 1973, patients were randomized to receive either involved field radiation treatment (RTIF) or extended field radiation treatment (RTEF). Since 1973 all patients have received RTEF, 4,000 cGy in four to five weeks, with a median follow-up of 7.4 years. Complete remission (CR) was achieved in 102 patients (94.4%), with no significant difference according to treatment or stage. Of the complete responders, 25 patients relapsed: 5/15 RTIF and 20/87 RTEF (P = .6). Twenty-one of 25 relapsing patients achieved a second CR. Disease free survival rates at five and ten years constituted: PS IA, 78.6% for both; PS IIA, 74.8% and 73.1% (P = .6); RTEF, 76.7% for both; RTIF, 73.3% and 66.7% (P = .7). Eighteen patients have died: eight of recurrent lymphoma, two of pulmonary embolus, one each of myocardial infarction, pulmonary fibrosis, and acute nonlymphocytic leukemia (ANLL) (following salvage chemotherapy), and one of diffuse histiocytic lymphoma (DHL). Four patients died in remission of unrelated causes. Actuarial survival rates at five and ten years constituted: PS IA, 95.7% and 72.4%; PS IIA, 89.6% and 81.4% (P = .3); RTIF, 93.7% for both; RTEF, 90.7% and 71.2% (P = .2). Age, sex, number of sites, and mediastinal involvement did not influence the outcome. Acute toxicity was modest and more frequent among those receiving RTEF (P = .08). Chronic toxicity (onset more than 30 days after completion of treatment) was identified in 16 patients: 1/16 RTIF; 15/92 RTEF (P = .5). Three patients developed a second malignancy: one carcinoma of the cervix in situ; one ANLL (following salvage chemotherapy); and one DHL of the stomach. At least 75% of patients with PS IA and IIA Hodgkin's disease were cured by radiation alone, with a risk of secondary malignancy following radiation alone of 0.9%. Since the majority of relapsing patients were successfully salvaged by chemotherapy, radiation alone appears to be the initial treatment of choice in this group of patients.

The neoplastic potential of gastric irradiation. IV. Risk estimates.

No significant tumor increase was found in the initial analysis of patients irradiated for peptic ulcer and followed through 1962. A preliminary study was undertaken 22 years later to estimate the risk of cancer due to gastric irradiation for peptic ulcer disease. A population of 2,049 irradiated patients and 763 medically managed patients has been identified. A relative risk of 3.7 was found for stomach cancer and an initial risk estimate of 5.5 X 10(-6) excess stomach cancers per person rad was calculated. A more complete follow-up is in progress to further elucidate this observation and decrease the ascertainment bias; however, preliminary data are in agreement with the Japanese atomic bomb reports.