Ultrastructural characterization and Fourier analysis of fiber cell cytoplasm in the hyperbaric oxygen treated guinea pig lens opacification model.

The structural characteristics of differentiated fiber cells in control and hyperbaric oxygen (HBO)-treated guinea pig lenses were examined by transmission electron microscopy (TEM). Emphasis was placed on cell damage, membrane integrity, and cytoplasmic texture. Given the faint gross opacities observed in HBO-treated lenses in previous studies, it was hypothesized that subtle but significant morphological differences due to oxidative damage exist between control and treated animals. Experimental animals received either 70 or 85 treatments with HBO (2.5 atm of 100% O(2) for 2.5 hr, 3 times per week for 5-7 months). All specimens were obtained within 24 hr of death. Freshly cut Vibratome lens sections were fixed and processed for low and high-magnification thin-section TEM analysis. Cytoplasmic texture was analyzed using Fourier and autocorrelation image processing techniques. Low-magnification analysis revealed relatively insignificant differences in general appearance between the fiber cells of the inner fetal and embryonic nuclei in control and HBO-treated guinea pigs. Both groups demonstrated cells of similar morphology with equivalent membrane complexity and homogeneous cytoplasmic texture. Evidence of any major cellular damage or extracellular space debris was not obvious. High-magnification analysis of the cytoplasm of the treated lenses exhibited a mild, yet detectable increase in texture compared with controls and was confirmed by Fourier analysis. Cytoplasmic texture increased in complexity with additional treatments. The absence of major cellular damage in the lenses of HBO-treated animals suggests a less conspicuous source of light scattering. The small changes in cytoplasmic organization observed between treated and control animals may entirely account for the increase in nuclear light scattering observed by slit lamp. The results obtained with this guinea pig/HBO model parallel many of the morphological data associated with human nuclear cataracts. The high-angle scattering observed in the lens of the HBO-treated guinea pig may represent the type of cytoplasmic reorganization that occurs with mild oxidation, effectively making it a valuable model for human lens aging.

Different patterns of renal cell killing after warm and cold ischemia.

Kidneys preserved for transplantation surgery sustain injuries caused by cold ischemia during storage. Additionally, kidneys harvested from non-heart-beating donors encounter the stress of warm ischemia. The aim of this study was to determine the specific cell types losing viability after warm and cold ischemia. In warm ischemia studies, the pedicles of left kidneys of Lewis rats were cross-clamped for up to 90 min. In cold ischemia studies, kidneys were flushed with cold University of Wisconsin solution and stored up to 48h at 0-1 degrees C. After warm or cold ischemia, kidneys were perfused via the renal arteries with Krebs-Henseleit bicarbonate (KHB) buffer at 37 degrees C, followed by trypan blue to label the nuclei of nonviable cells. Warm ischemia for 90 min caused renal failure and led to injury of proximal tubular cells, e.g., loss of brush borders, cast formation and trypan blue labeling. Cold ischemia for 48 h also caused renal failure but, unlike warm ischemia, caused trypan blue labeling of glomerular podocytes and peritubular endothelial cells. In warm ischemia-induced injury, electron microscopy showed shedding of microvilli and marked swelling of proximal tubular cells, microvilli and mitochondria. In cold ischemia-induced injury, podocytes were blebbed and swollen, and their pedicels were detached from the basement membrane, but disruption in proximal tubules was milder. In conclusion, warm ischemia triggers injury primarily to proximal tubular cells, whereas cold ischemia damages glomerular podocytes and peritubular endothelial cells in addition to proximal tubules.

Carolina rinse solution minimizes kidney injury and improves graft function and survival after prolonged cold ischemia.

BACKGROUND: Kidney damage caused by cold ischemia-reperfusion injury promotes adverse outcomes after renal transplantation. The purpose of this study was to determine whether Carolina rinse solution (CRS) used at the end of cold ischemic storage decreases kidney injury and improves graft function and survival. METHODS: Inbred male Lewis rats were used as donors and recipients. Left kidneys were removed from donor rats, infused with cold University of Wisconsin solution, and stored for 24, 30, or 48 hr at 0-1 degrees C. Just before implantation, kidneys were flushed with either Ringer's solution or CRS at 35-37 degrees C or were not treated. Kidneys were then transplanted into recipient rats with removal of both native kidneys. RESULTS: Survival and renal function were analyzed over a 14-day postoperative period. Among rats receiving kidneys after 24-hr cold storage, creatinine clearance was 75% greater in rats transplanted with kidneys flushed with CRS compared with Ringer's solution or nontreatment. In animals receiving kidneys after 30-hr cold storage, recipient survival after CRS was significantly higher than with Ringer's solution or without flushing (80% vs. 25% and 17%, respectively). However, CRS failed to prevent renal graft failure after 48 hr of cold storage (14% survival with CRS vs. 0% with Ringer's solution). In separate ex vivo studies, nonviable cell nuclei were labeled by trypan blue after cold preservation and brief warm reperfusion. CRS decreased podocyte and peritubular endothelial cell killing associated with cold ischemia-reperfusion injury. CONCLUSION: Flushing renal explants with warm CRS before implantation diminishes cold ischemia-reperfusion injury and improves the function and survival of transplanted kidneys.

Uptake of the neurotransmitter histamine into the eyes of larvae of the barnacle (Balanus amphitrite).

The photoreceptors of adult barnacles use histamine as their neurotransmitter and take up (3)H-histamine selectively from the extracellular medium. We assayed for the uptake of (3)H-histamine into the eyes of the free-swimming (nauplius) and settling (cyprid) larval stages of Balanus amphitrite. The extracellular space of nauplii proved permeable to dyes below about 800 molecular weight (MW), indicating that (3)H-histamine (MW 111) introduced into seawater would have access to internal structures. (3)H-Histamine was taken up into nauplii by a process with a K(D) of 0.32 microM. Uptake was antagonized by chlorpromazine, which also blocks uptake of (3)H-histamine into adult photoreceptors. In autoradiographs of serial sections of nauplii and cyprids incubated in (3)H-histamine, the ocelli and compound eyes were labeled; other structures in the animal were not. No eyes or other structures were labeled with (3)H-serotonin, a related amine whose transporter commonly transports histamine as well. These experiments show that a histamine-specific transporter similar to that found in the adult is expressed in all of the eyes of barnacle larvae. In the ocelli, where photoreceptors and pigment cells may be distinguished in the light microscope, label was unexpectedly concentrated far more over the pigment cells than over the photoreceptors.