Alveolar epithelial cell death adjacent to underlying myofibroblasts in advanced fibrotic human lung

Earlier work from this laboratory showed that abnormal fibroblast phenotypes isolated from fibrotic human lung produce factor(s) capable of inducing apoptosis and necrosis of alveolar epithelial cells in vitro [B. D. Uhal, I. Joshi, A. True, S. Mundle, A. Raza, A. Pardo, and M. Selman. Am. J. Physiol. 269 (Lung Cell. Mol. Physiol. 13): L819-L828, 1995]. To determine whether epithelial cell death is associated with proximity to abnormal fibroblasts in vivo, the spatial distribution of epithelial cell loss, DNA fragmentation, and myofibroblasts was examined in the same tissue specimens used previously for fibroblast isolation. Paraffin sections of normal and fibrotic human lung were subjected to in situ end labeling (ISEL) of fragmented DNA and simultaneous immunolabeling of alpha-smooth muscle actin (alpha-SMA); replicate samples were subjected to electron microscopy and detection of collagens by the picrosirius red technique. Normal human lung exhibited very little labeling except for positive alpha-SMA immunoreactivity of smooth muscle surrounding bronchi and vessels. In contrast, fibrotic human lung exhibited moderate to heavy ISEL of interstitial, cuboidal epithelial, and free alveolar cells. ISEL of the alveolar epithelium was not distributed uniformly but was most intense immediately adjacent to underlying foci of alpha-SMA-positive fibroblast-like interstitial cells. Both electron microscopy and picrosirius red confirmed epithelial cell apoptosis, necrosis, and cell loss adjacent to foci of collagen accumulation surrounding fibroblast-like cells. These results demonstrate that the cuboidal epithelium of the fibrotic lung contains dying as well as proliferating cells and support the hypothesis that alveolar epithelial cell death is induced by abnormal lung fibroblasts in vivo as it is in vitro.

Mechanisms of liquid flux across pulmonary alveolar epithelial cell monolayers

Active transport of sodium by pulmonary alveolar epithelial cells (AEC) is believed to be an important component of edema clearance in the normal and injured lung. Data supporting this premise have come from measurements of sodium movement across AEC monolayers or from perfused lung model systems. However, direct measurement of fluid flux across AEC monolayers has not been reported. In the present work, AEC were studied with an experimental system for the measurement of fluid flux (Jv) across functionally intact cell monolayers. Primary adult rat type II alveolar epithelial cells were cultured on 0.8 micron nuleopore filters previously coated with gelatin and fibronectin. Intact monolayers were verified by high electrical resistance (> 1000 omega) at 4-5 d of primary culture. At the same time interval, transmission electron microscopy revealed cells with type I cell-like morphology throughout the monolayer. These were characterized by both adherens and tight junctional attachments. Fluid flux across the monolayers was measured volumetrically over a period of 2 h in the presence of HEPES-buffered DMEM containing 3% fatty acid-free bovine serum albumin. Flux (Jv) was inhibited 39% by 1 X 10(-4) M ouabain (P < 0.01) and 27% by 5 X 10(-4) M amiloride (P < 0.05). These data support the concept that AEC Na+/K(+)-ATPase and Na+ transport systems are important determinants of AEC transepithelial fluid movement in vitro.

Quantitation of ischemic damage in the rat retina

In order to determine thresholds for irreversible cellular injury in the rat retina, timed acute no-flow ischemic episodes of 30-180 min duration were produced by elevation of intraocular pressure (IOP) above systolic pressure. Quantitation of irreversible degeneration and cell loss following a 2-week post-ischemic interval was performed by computer-assisted measurements from histologic sections. Alterations of thickness of retinal layers and linear cell density were determined for ischemia of selected durations (30, 60, 80, 90, 120 and 180 min). Different thresholds were evident for inner and outer retinal damage. Neurons of the inner nuclear layers showed extensive loss with episodes at 60 min. Decrease in the thickness of the inner plexiform layer provided the best index of this inner nuclear damage. The outer retina was more resistant, with photoreceptors showing extensive damage only after 90 min in conjunction with pigment epithelial metaplasia and degeneration. Two-hour episodes produced full-thickness degeneration with loss of pigment epithelium and sparing of the peripheral retina. Greater sensitivity of the inner retina suggested problems with restoration of the retinal circulation. Horseradish peroxidase infusions did reveal central microcirculatory defects in retinal wholemounts of some specimens with episodes longer than 60 min. Refinements of the methods resulted in outcomes sufficiently reproducible for quantitative assessment of acute ischemic injury. The rat retina provides an economical basic tissue model of acute ischemic injury affecting neurons, glia, and microvasculature. Quantitation of this injury promises great utility in testing agents with potentially protective effects on acute ischemic injury.

Enhanced survival of motoneurons in the chick lateral motor column: effects of embryonic skeletal muscle extracts and myoblast-conditioned medium

Muscle-derived factors have shown neurotrophic effects in culture, but their possible effects on the maintenance of embryonic motoneurons have not been demonstrated in vivo. Soluble extracts derived from embryonic chick muscle, or medium conditioned by chick myoblasts, were instilled onto the chorioallantoic membrane (CAM) between the 5th and 11th days of incubation. Counts of the lumbar lateral motor column (LMC) at embryonic day 12 revealed modest but significant increases (12-15%) in motoneuron number for these experimental groups as compared with control treatments. The results suggest that sustaining effects of muscle-derived factors on motoneurons may be demonstrated on the developing LMC by the simple expedient delivery via the CAM, and that these factors can modify the normal program of cell death occurring during this critical period of development.

Subclavian artery occlusion 42 years after mastectomy and radiotherapy

Left subclavian artery occlusion developed in a patient 42 years after a left radical mastectomy and radiotherapy. The vascular supply was successfully reconstructed by a graft from the right subclavian artery to the left brachial artery. Clinical and experimental evidence has demonstrated that radiotherapy can damage large vessels [2,4,5]. It is our contention that radiotherapy was the causative factor in the case of subclavian artery occlusion reported herein.

Lymphocyte-induced corneal neovascularization: a morphologic assessment

Lymphocytes obtained from mesenteric lymph nodes of rabbits were stimulated in vitro by concanavalin A and injected into the corneas of allogeneic hosts. Controls were nonstimulated, killed, or autogeneic lymphocytes injected into the contralateral corneas. The stimulated cells were significantly better inducers of neovascular growth. Histologic observations of the vascularized corneas showing marked mononuclear reactions at the limbus, coupled with the requirement of allogenicity, suggest that there was immunologic recognition of the implanted cells. Stimulated allogeneic blast cells may amplify this host recognition by their elaboration of lymphokines or enhanced antigenicity. The apparent importance of allogenicity for the induction of vessel growth in these experiments may be significant in the pathogenesis tumor-induced or graft-related corneal neovascularization.

Phase Change in Liquid Face Seals II—Isothermal and Adiabatic Bounds With Real Fluids

Phase change effects in parallel and tapered liquid face seals are studied analytically. Both an isothermal and adiabatic model of low Reynolds number flow are considered by numerical integration of the descriptive equations for a real fluid. Real fluid thermodynamic properties are calculated for each step, using a computer program for the steam tables or thermodynamic properties of the fluid considered. Examples are presented for water. The general conclusions are: 1. For low leakage rate the isothermal model is more accurate and for high leakage rates the adiabatic model is more accurate. 2. Both parallel models, ordinarily neutrally stable with a liquid, yield the same general conclusions about stability. If the sealed fluid is near enough to saturation conditions, there will exist generally two values of the film gap, h, which yield the same separating force under a given set of operating conditions. For a given speed, face excursions about the larger value are stable, but excursions about the lower value are unstable, either growing to the larger h if displaced apart or collapsing if displaced together. 3. The transient of collapse is described by the adiabatic model which predicts a catastrophic collapse and then either failure or explosive return to a larger value of h. 4. Converging seals (ordinarily stable with a liquid at some given value of h) may become unstable, the phase change effect dominating the behavior and giving rise to collapse as described above. 5. The mass leakage rate is reduced significantly below the all liquid value when boiling occurs.

A comparison of cancer occurrence in allergic and nonallergic populations

Patients with significant allergy were surveyed with regard to the incidence of malignancy and a control group of nonallergic individuals was similarly reviewed. In the allergic population of 500 persons in the cancer-bearing age group, there were 12 malignancies, while the nonallergic group of 421 individuals had 14 malignancies. The Chi-squared test of these data gives a value of 0.75, which indicates that there is no significant difference in the incidence of malignancy in the allergic and nonallergic groups. As one would expect, the test of independence between age, cancer and allergy using the Chi-squared statistic is rejected.

Suppressive effects of indomethacin on thermally induced neovascularization of rabbit corneas

In 16 rabbits with bilateral corneal burns, indomethacin was administered topically to one eye on each day after the lesion was made to determine the effect of a prostaglandin inhibitor on the corneal neovascular response to experimental thermal burns. Comparison of the two eyes showed a reduction of both hyperemia and neovascularization in indomethacin-treated eyes during the first five days after injury. Histologic observations during this period showed a reduction in polymorphonuclear cell infiltration in the treated corneas. Inhibition of prostaglandin synthesis by indomethacin apparently led to a reduction in the inflammatory response and the subsequent corneal neovascularization.

Phase Change in Liquid Face Seals

A study is made of boiling (or phase change) in liquid face seals. An appropriate model is set up and approximate solutions obtained. Some practical illustrative examples are given. The principal conclusions are: 1) Boiling may occur more often than has been suspected particularly when the sealed liquid is near saturation conditions. 2) The temperature variation in a seal clearance region may not be very great and the main reason for boiling is the flashing which occurs as the pressure decreases through the seal clearance. 3) There are two separate values of the parameter (h/ω2) (and associated radii where phase change takes place) which provide the same separating force under a given set of operating conditions. For a given speed seal face excursions about the larger spacing are stable, but excursions about the smaller spacing are unstable, leading to a growth to the larger spacing or a catastrophic collapse.

Pathology of the pigment epithelium and retina in rabbits poisoned with lead

Multifocal lesions of the retinal pigment epithelium were observed in rabbits fed a diet contaning 0.5% lead subacetate for periods of up to 2 years. Groups of pigment epithelial cells became congested with a lipofuscin pigment which was apparently derived from phagosomes of rod outer segments. Lipofuscin granules displaced melanin granules from the apical surface of the retinal pigment epithelial cells and resulted in conspicuous brown pigmentation of these cells in albino animals. Migration of macrophages and pigment epithelial cells into the subretinal space was common in affected areas. This pathology was not observed in the pigment epithelium of the ora serrata, or ciliary body. At the latest time periods, the abnormal lipofuscin pigmentation subsided, and degeneration of photoreceptors occurred. The pathogenesis of the lesions is discussed.

Long-term complications of beta-radiation therapy in ophthalmology

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The Relation Between the Rubbing Interface Temperature Distribution and Dynamic Thermocouple Temperature

The dynamic thermocouple formed by the moving junction of two dissimilar metals is known as the Herbert-Gottwien thermocouple. It is analyzed for the case of two semi-infinite bodies having a continuous rectangular rubbing contact area. Methods for determining the interface temperature after Chao and Trigger are presented; and the dynamic thermocouple, or Herbert-Gottwien temperature, is related to the temperature distribution. It is found that the dynamic thermocouple temperature is a weighted average of the latter and the weighting function is independent of temperature distribution and depends only on the geometry of the contact area. The weighting function assumes a higher value toward the periphery than it does in the interior of the contact area. The above ambient dynamic thermocouple temperature is found to be directly proportional to a geometry factor of the contact area and to the total heat flux across the contact area.

The Effect of I.D.U. on Experimental and Clinical Herpes Simplex Infections

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