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Introduction: Septic shock is associated with high mortality and hemodynamic impairment. The use of corticoids is a common therapeutic tool in critically ill patients. However, data on the mechanisms and prognostic ability of hemodynamic improvement by adjunctive steroids are rare. This study primarily aimed to evaluate short-term effects of hydrocortisone therapy on catecholamine requirement and hemodynamics derived from transpulmonary thermodilution (TPTD) in 30 critically ill patients with septic shock and a 28 days mortality rate of 50%. Methods: Hydrocortisone was administered with an intravenous bolus of 200 mg, followed by a continuous infusion of 200 mg per 24 h. Hemodynamic assessment was performed immediately before as well as 2, 8, 16, and 24 h after the initiation of corticoids. For primary endpoint analysis, we evaluated the impact of hydrocortisone on vasopressor dependency index (VDI) and cardiac power index (CPI). Results: Adjunctive hydrocortisone induced significant decreases of VDI from 0.41 (0.29-0.49) mmHg -1 at baseline to 0.35 (0.25-0.46) after 2 h ( P  < .001), 0.24 (0.12-0.35) after 8 h ( P  < .001), 0.18 (0.09-0.24) after 16 h ( P  < .001) and 0.11 (0.06-0.20) mmHg -1 after 24 h ( P  < .001). In parallel, we found an improvement in CPI from 0.63 (0.50-0.83) W/m 2 at baseline to 0.68 (0.54-0.85) after 2 h ( P  = .208), 0.71 (0.60-0.90) after 8 h ( P  = .033), 0.82 (0.6-0.98) after 16 h ( P  = .004) and 0.90 (0.67-1.07) W/m 2 after 24 h ( P  < .001). Our analyses revealed a significant reduction in noradrenaline requirement in parallel with a moderate increase in mean arterial pressure, systemic vascular resistance index, and cardiac index. As a secondary endpoint, our results showed a significant decrease in lung water parameters. Moreover, changes in CPI (ΔCPI) and VDI (ΔVDI) after 24 h of hydrocortisone therapy revealed accurate prognostic ability to predict 28 days mortality (AUC = 0.802 vs 0.769). Conclusion: Adjunctive hydrocortisone leads to a rapid decrease in catecholamine requirement and a substantial circulatory improvement in critically ill patients with septic shock.

Background and Goals: Risk stratification for the need for therapeutic endoscopy and prediction of mortality in patients with upper gastrointestinal bleeding (UGIB) can be assessed by several scores. However, current scores are not validated for variceal bleeding and Intensive Care Unit (ICU) patients. The aim of this study was to evaluate potential parameters for the prediction of UGIB and patient outcomes., Patients and Study Methods: In this monocenter retrospective observational study, data from all esophagogastroduodenoscopies (EGD) between November 2014 and February 2020 with suspected hemorrhage in our ICU were evaluated., Results: Out of 345 included EGD, 42.3% of UGIB was diagnosed. 51.9% needed endoscopic intervention. Overall, 52.3% of included patients with UGIB died. Logistic regression showed that preceding variceal or non-variceal UGIB ( p  < .001), serum lactate ( p  = .001), heart rate (HR) ( p  = .005), and blood transfusions ( p  = .001) were significant predictors of UGIB. Previous UGIB ( p  < .001), male sex ( p  = .015), known varices ( p  < .001), serum albumin ( p  = .19) and use of catecholamines ( p  = .040) were significant predictors for the need of endoscopic intervention. Higher mortality was significantly associated with the usage of steroids ( p  < .001), malignant preconditions ( p  = .021), serum albumin ( p  = .020) and prolonged PTT (partial thromboplastin time) ( p  = .001)., Conclusions: We were able to identify additional parameters that had previously not been included in existing scores to predict the risk of UGIB, the need for therapeutic endoscopy and mortality in ICU patients. Therefore, an extension of these scores is necessary. Further validation of identified parameters in multicenter trials is needed to improve risk scores for ICU patients.

Background: Outcome of severe acute pancreatitis (SAP) highly depends on the degree of systemic inflammation and organ failure. Although treatment approaches targeting the inflammatory cascade have failed in pancreatitis, recent studies suggest that extracorporeal cytokine adsorption effectively reduces concentrations of pro-inflammatory cytokines and potentially improves the outcome of sepsis., Methods: Sixteen patients with SAP, presenting within 7 days upon onset of pain, an APACHE-II score of ≥10 and ≥1 marker of poor prognosis, received 2 consecutive 24-h treatments with CytoSorb® extracorporeal cytokine adsorption (intervention group). Hemodynamics, organ failure, and mortality were compared with an APACHE-II score-matched retrospective control group of 32 patients., Results: The primary objective (20% decrease in the vasopressor dependency index or 20% increase in the cardiac index) was reached in 68.8% of the intervention and 28.1% of the control patients (p = 0.007), respectively. The cytokine adsorption significantly reduced IL-6 (-1998 pg/ml, p = 0.005) serum levels and resulted in stable CRP (p = 0.101) and decreased PCT (p = 0.003) levels in contrast to increased CRP (p = 0.014) and stable PCT levels (p = 0.695) in the control group. While mortality and improvement of respiratory failure were similar in both groups, renal failure significantly improved (change of KDIGO classification 72 h postcytokine adsorption [-1 vs. 0, p = 0.005]) and the SOFA score significantly decreased (day 5: -1.8 ± 2.0 vs. 1 ± 3.8, p = 0.013) in the intervention group., Conclusion: Cytokine adsorption might be an effective treatment option to stabilize hemodynamics in SAP. It decreases levels of the pro-inflammatory marker IL-6 and stabilizes organ function according to serial SOFA score assessments., (© 2022 The Authors. Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Introduction: Visualization of B-lines via lung ultrasound provides a non-invasive estimation of pulmonary hydration. Extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) assessed by transpulmonary thermodilution (TPTD) represent the most validated parameters of lung water and alveolocapillary permeability, but measurement is invasive and expensive. This study aimed to compare the correlations of B-lines scores from extensive 28-sector and simplified 4-sector chest scan with EVLWI and PVPI derived from TPTD in the setting of intensive care unit (primary endpoint)., Methods: We performed scoring of 28-sector and 4-sector B-Lines in 50 critically ill patients. TPTD was carried out with the PiCCO-2-device (Pulsion Medical Systems SE, Maquet Getinge Group). Median time exposure for ultrasound procedure was 12 minutes for 28-sector and 4 minutes for 4-sector scan., Results: Primarily, we found close correlations of 28-sector as well as 4-sector B-Lines scores with EVLWI (R 2 = 0.895 vs. R 2 = 0.880) and PVPI (R 2 = 0.760 vs. R 2 = 0.742). Both B-lines scores showed high accuracy to identify patients with specific levels of EVLWI and PVPI. The extensive 28-sector B-lines score revealed a moderate advantage compared to simplified 4-sector scan in detecting a normal EVLWI ≤ 7 (28-sector scan: sensitivity = 81.8%, specificity = 94.9%, AUC = 0.939 versus 4-sector scan: sensitivity = 81.8%, specificity = 82.1%, AUC = 0.902). Both protocols were approximately equivalent in prediction of lung edema with EVLWI ≥ 10 (28-sector scan: sensitivity = 88.9%, specificity = 95.7%, AUC = 0.977 versus 4-sector scan: sensitivity = 81.5%, specificity = 91.3%, AUC = 0.958) or severe pulmonary edema with EVLWI ≥ 15 (28-sector scan: sensitivity = 91.7%, specificity = 97.4%, AUC = 0.995 versus 4-sector scan: sensitivity = 91.7%, specificity = 92.1%, AUC = 0.978). As secondary endpoints, our evaluations resulted in significant associations of 28-sector as well as simplified 4-sector B-Lines score with parameters of respiratory function., Conclusion: Both B-line protocols provide accurate non-invasive evaluation of lung water in critically ill patients. The 28-sector scan offers a marginal advantage in prediction of pulmonary edema, but needs substantially more time than 4-sector scan.

Introduction: The purpose of this study was to evaluate the amount of calcium hydroxide (Ca[OH]2) removed by irrigation with different volumes and activation methods., Methods: One hundred thirty extracted straight, single-rooted human teeth were instrumented to size 45/.04. One hundred twenty teeth were filled with radioactively marked Ca(OH)2 and a gutta-percha point; 10 teeth with only gutta-percha served as a negative control. All specimens were stored in saline solution (7 days at 35°C). After storage, teeth were randomly divided into 12 groups (n = 10). The gutta-percha was taken out, and Ca(OH)2 was removed either by irrigation with different volumes (0 mL, 0.5 mL, 1 mL, 2 mL, 4 mL, or 8 mL) or mechanical activation with a 2- or 4-mL volume using a file (Instr) (FlexMaster size 45/.04; VDW, Munich, Germany), a brush (CanalBrush [CB]; Coltène/Whaledent, Langenau, Germany), or passive ultrasonic irrigation (PUI, smooth wire). Irrigation was performed by alternating 40% citric acid and 3% sodium hypochlorite. Residual Ca(OH)2 was measured by scintillation and expressed as a percentage of the original Ca(OH)2., Results: Increasing the irrigation volume led to a significant decrease (P < .05) of residual Ca(OH)2 (0 mL [98.5%], 0.5 mL [21.7%], 1 mL [16.5%], 2 mL [12.9%], 4 mL [8.7%], 8 mL [5.0%], and negative control [0.0%]). Activation led to less residual Ca(OH)2 (2 mL Instr [12.0%], 2 mL CB [11.7%], 2 mL PUI [9.1%], 4 mL Instr [8.5%], 4 mL CB [7.4%], and 4 mL PUI [6.2%]), with significant differences according to the PUI (P < .05)., Conclusions: No irrigation procedure was able to remove Ca(OH)2 completely. PUI was the most effective activation method. However, irrigation with an 8-mL volume was the most effective., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: The interaction between kidney urothelium and crystals is a critical event in the growth of renal calculi. When studying calcium oxalate monohydrate (COM) crystal binding to Madin-Darby canine kidney (MDCK) cells in culture, we observed that crystals also attached to areas on the coverslips devoid of cells. This phenomenon could be the result of substances produced by the cells that adhere to the glass and subsequently bind COM crystals. We investigated the characteristics of this COM binding substance., Methods: Media was collected from cultures of MDCK cells (conditioned media) and proteins were separated by high performance liquid chromatography. The molecular weights and purity of isolated proteins were determined by polyacrylamide gel electrophoresis. The conditioned media and each separated fraction were applied to glass and to MDCK cells and COM-binding ability determined using 14C-labeled crystals. The binding of radio-labelled calcium oxalate dihydrate, brushite, uric acid, and apatite to coverslips were also studied., Results: Fourteen times more COM bound to coverslips incubated with conditioned media than those with control media. The molecular weight of the protein bound to the glass was determined to be 200 kDa. The COM crystals binding to this protein was 1.5 micro g/ng. Other crystals bound to a lesser extent. The incubation of cells with this protein inhibited COM binding by 39%., Conclusion: The MDCK cells produce a 200-kDa protein that has a high binding affinity for COM crystals. This protein binds to glass and is responsible for crystal binding to areas devoid of cells. This protein also has an inhibitory effect on COM binding to MDCK cells in culture.

Background: Renal cell or tissue injury results in a loss of membrane lipid asymmetry and/or loss of cell polarity, and both events lead to changes on the surface of the cell membranes that enhance crystal attachment. We have proposed two distinct mechanisms of crystal attachment following membrane changes induced by various modes of injury., Methods: Annexin V was used to determine whether phosphatidylserine (PS) exposure on the cell membrane surface plays a role in calcium oxalate monohydrate (COM) crystal attachment to cells that have lost their polarity as well as to cells that have lost their lipid asymmetry. We utilized two different experimental models of injury to renal epithelial cells in culture. The first model used calcium ionophore A23187 to induce a loss of lipid asymmetry, and the second model used EGTA to break down tight junctions and lose cell polarity., Results: Inner medullary collecting duct cells that have lost lipid asymmetry demonstrated an increase in the number of cells that bound annexin V. However, when cells lost their polarity, they did not bind annexin V. In addition, the attachment of crystals to cells following a loss of cell polarity was not inhibited by annexin V., Conclusions: This study indicates that both individual cell injury (loss of lipid asymmetry) and generalized cell monolayer injury (loss of cell polarity) result in the presentation of different cell surfaces and that both forms of injury result in an increased affinity for crystal attachment. Both mechanisms could be important independently or collectively in the retention of microcrystals to renal collecting duct cells in urolithiasis.

A molecular mechanism of crystal attachment to renal cells after injury has been proposed in which the exposure of phosphatidylserine (PS) on the cell membrane surface following injury provides attachment sites for calcium-containing crystals. Annexin V was used to determine whether injury to kidney cells by oxalate in culture resulted in PS exposure on the cell surface. When continuous cultures of intermedullary collecting duct cells were exposed to various levels of oxalate, a dose-dependent increase in PS exposure was observed on the cell surfaces. Initially, only scattered cells expressed PS on the surface. However, as the level of oxalate increased, groups of cells began to express PS, suggesting that the injured cells may have an influence on neighboring cells. Exposure of PS on the cell membrane surface correlated with a corresponding increase in calcium oxalate monohydrate crystal attachment to the cells. This indicates that damage to kidney epithelial cells by elevated concentrations of urinary components, in this case oxalate, could result in exposure of PS on cells, which could provide a point of fixation or nucleation for calcium-containing crystals.

Purpose: Cultured kidney epithelial cell lines have frequently been used in urolithiasis research, and in particular in studies related to the interactions between stone crystals and cell membranes. There is evidence that when epithelial cell lines are transformed or serially passed to immortalize them, they experience changes in both cell physiology and morphology. Stone research utilizing cell cultures is frequently necessary due to the lack of an animal model for spontaneous stone disease. However, the interpretation of these cell culture research studies might be clouded by any significant differences in cell physiology between primary cells and continuous cell cultures. Therefore, the present study was conducted to compare calcium oxalate monohydrate (COM) crystal attachment to two primary kidney epithelial cell lines and to various continuous cell lines., Materials and Methods: The cell lines surveyed were primary mouse proximal tubule cells (pMPT), primary inner medullary collecting duct cells (pIMCD), semi-continuous inner medullary collecting duct cells (cIMCD), BSC-1 cells, COS-1 cells, LLC-PK1 cells, MDCK cells, NRK-52E cells, and OK cells. All cell lines were cultured under identical conditions and the amount of COM attachment was measured using radioactive labeled COM crystals., Results: COM crystal interaction with continuous kidney epithelial cells varied by a factor of two among the different cell lines. In general, cells that grew as regular, confluent cell monolayers, such as pMPT, pIMCD and cIMCD cells, exhibited the lowest levels of crystal attachment. Neither changes in membrane fluidity nor loss of normal epithelial cell membrane asymmetry seemed to correlate well with crystal attachment. After nine days of continuous cell culture, COM attachment to cIMCD cells dropped by 61 percent while crystal attachment to MDCK cells remained unchanged. It is unclear what makes these cell lines more resistant to crystal attachment compared to continuous cell lines., Conclusions: The significant difference in COM attachment between primary kidney epithelial cells and continuous epithelial cell cultures and the apparent differences in growth morphology between primary and continuous cell cultures must be considered when selecting a cell line for use in kidney stone research. Comparison of cIMCD cells and MDCK cells during extended culture time revealed one possible explanation for the differences in COM attachment: the formation of a mature, end-differentiated, non-dividing cell monolayer could protect the cells from crystal attachment.

Nitric oxide (NO) has been associated with lung inflammation following exposure to silica. L-arginine can be converted to NO and L-citrulline by nitric oxide synthase (NOS), or into urea and L-ornithine by arginase. We tested the hypothesis that after instillation of silica into rat lungs in vivo, lung inflammatory cells increase L-arginine metabolism by both NOS and arginase, which is associated with an increase in L-arginine uptake. We isolated lung inflammatory cells 3 d after silica or saline (control) exposure. The uptake of [3H]L-arginine at 24 h by cells from silica-exposed lungs (73.9 +/- 4.8%) was significantly greater than uptake by control cells (24.7 +/- 2.2%; P < 0.05) and was a saturable process. The greater [3H]L-arginine uptake by cells from silica-exposed lungs was associated with greater NO and urea production than by control cells. The uptake of [3H]L-arginine by cells from control or silica-exposed lungs was blocked in a dose-dependent manner by L-ornithine (an inhibitor of L-arginine transport) and by Nomega-nitro-L-arginine methyl ester (L-NAME) (an NOS inhibitor), but not by L-valine (an arginase inhibitor). The production of NO by cells from silica-exposed lungs was completely blocked by L-NAME. The addition of L-arginine to media resulted in dose-dependent production of NO and urea. The results show that lung inflammatory cells increase L-arginine uptake and metabolism by both NOS and arginase following in vivo silica exposure. The increase in L-arginine uptake may represent a mechanism to maintain an intracellular supply of this amino acid. NO can react to generate peroxynitrite, a potential mediator of lung injury following silica exposure.

Crystal polymorphism is exhibited by calcium oxalates in nephrolithiasis, and we have proposed that a shift in the preferred crystalline form of calcium oxalate (CaOx) from monohydrate (COM) to dihydrate (COD) induced by urinary macromolecules reduces crystal attachment to epithelial cell surfaces, thus potentially inhibiting a critical step in the genesis of kidney stones. We have tested the validity of this hypothesis by studying both the binding of monohydrate and dihydrate crystals to renal tubule cells and the effect of macromolecular urinary solutes on crystal structure. Renal tubule cells grown in culture bound 50% more CaOx monohydrate than dihydrate crystals of comparable size. The effects of macromolecules on the spontaneous nucleation of CaOx were examined in HEPES-buffered saline solutions containing Ca2+ and C2O4(2-) at physiologic concentrations and supersaturation. Many naturally occurring macromolecules known to be inhibitors of crystallization, specifically osteopontin, nephrocalcin and urinary prothrombin fragment 1, were found to favor the formation of calcium oxalate dihydrate in this in vitro system, while other polymers did not affect CaOx crystal structure. Thus, the natural defense against nephrolithiasis may include impeding crystal attachment by an effect of macromolecular inhibitors on the preferred CaOx crystal structure that forms in urine.

Purpose: Urolithiasis is clearly a multifaceted process, progressing from urine supersaturation to the formation of mature renal calculi. Retention of microcrystals by the urothelium is a critical event in stone maturation. Membrane phospholipids appear to be involved in the attachment of stone crystals to kidney epithelium., Materials and Methods: The current study quantitates crystal-membrane interactions following selective changes in the red blood cell (RBC) membrane phospholipid composition by using a crystal-induced membranolytic assay., Results: Membrane enrichment with anionic phospholipids was found to greatly increase crystal-membrane interactions. Crystal-membrane interaction was associated with an increase in the negative charge on the RBC membrane surface., Conclusions: Specific membrane compositions seem to facilitate the formation of crystal attachment region on the RBC surface that is necessary for effective crystal attachment to the cell membrane.

Background: Leukotriene B4 (LTB4) serum and plasma concentrations were reported to be higher in some asthmatic patients than in normal subjects; however, reported LTB4 concentrations in normal subjects vary widely. One study suggested that blood clotting causes the increased LTB4 concentration., Objective: To determine whether LTB4 concentration is increased in asthmatic patients, and whether it is affected by clotting., Methods: We studied seven normal subjects and nine clinically stable asthmatic patients. Venous blood was drawn into test tubes without additives; containing heparin; or containing heparin and cyclo- and lipoxygenase inhibitors. Cells were separated after 30 minutes. Leukotriene B4 was measured by radioimmunoassay following its extraction from serum or plasma. In three subjects, plasma was separated also at times 0 through 30 minutes., Results: Serum and plasma concentrations of LTB4 in normal volunteers and asthmatic patients were similar, but the variance of LTB4 concentrations among the asthmatic patients was significantly higher than in the normal subjects. Leukotriene B4 concentrations, measured in plasma only, were significantly reduced in both asthmatic and nonasthmatic subjects in the presence of inhibitors. There was no significant difference in LTB4 concentrations between time 0 and 30 minutes, but there was considerable variability., Conclusions: We conclude that clotting is unlikely to affect serum LTB4 concentrations. Leukotriene B4 serum and plasma concentrations are not consistently increased in asthmatic patients; however, LTB4 is synthesized during and possibly after blood has been drawn. Proper handling of the specimens and probably the addition of cyclo-oxygenase and lipoxygenase inhibitors is of the utmost importance for accurate LTB4 determination.

One of the critical steps in the development of crystal-induced lung diseases is thought to be the interaction of crystal surfaces with cell membranes. The effect of chemical modifications of the surface of alpha-quartz on the development of lung disease has been investigated by treating quartz with various organosilanes. The functional groups attached to the quartz surfaces were (-CN), (-CH3), (-NH2), and -(N(CH3)3+). After intratracheal injection of each modified crystal at a constant surface area into mice, pulmonary inflammation and fibrosis were assessed 6 wk postexposure to the crystals by lung wet weight (lung index) and by the level of hydroxyproline in the lung. The crystals showing the highest degree of biologic activity were native quartz, which has a negative charge, -N(CH3)3+ modified quartz, which has a positive charge, and -CN modified quartz, which has no charge. One of the crystals with chemical groups capable of hydrogen bonding, the -NH2 modified quartz, was as unreactive as the crystal preparation modified with a hydrophobic group, -CH3. If the -CH3 and -NH2 modified quartz are compared as a less reactive group with the more reactive native quartz and -N(CH3)3+ modified quartz, these experiments suggest that electrostatic interactions may be more important in determining effective biologic activities than are hydrogen bonding interactions.

A murine model of experimental silicosis has been developed after the intratracheal injection of alpha-quartz crystals. Pulmonary inflammation was monitored by increases in wet lung weight and cell number and protein content of the lung lavage fluid; fibrosis was assessed by measuring increases in hydroxyproline content of the lungs. Acute pulmonary cellular inflammation occurred between weeks 1 and 2, followed by a chronic inflammatory response at week 12. Lung hydroxyproline content, an indication of collagen deposition, was initiated as early as 1 week after silica injection and continued to increase steadily over time. The inflammatory and fibrotic changes induced by silica appeared to be a specific effect of the injection of this toxic particulate and not the result of the introduction of a foreign body, because mice injected with silica crystals were found to have significantly greater increases in acute cellular inflammation and chronic collagen deposition than did mice injected with latex beads. A possible role for the immune system in modulating silica-induced damage was suggested by the variability in response of six different strains of mice (C3H/He, CBA/J, Balb/c, DBA/2, C57BL/6, C57BL/10), which differed at specific genetic loci. Both strains with high (DBA/2) and low (C3H/He) response demonstrated similar patterns of inflammation and fibrosis over a period of 12 weeks. This model demonstrates great potential in future studies for elucidating the role of the immune system in the development of pulmonary inflammation and fibrosis induced by toxic inorganic particulates.

Crystalline hydroxyapatite is a component of bone, teeth, and numerous pathological calcifications. The apatite crystal structure can accommodate a wide variety of atomic substitutions which gives apatite crystals an unusually high degree of variability in biochemical and physical properties. Apatite crystallites interact with numerous cellular systems in vivo, and some of these interactions may lead to altered cellular function. One measure of crystal-membrane interactions is crystal-induced membranolysis of human red blood cells. Hemolytic potentials at constant crystal surface areas were measured at 1, 2, and 4 hours for 29 different preparations of apatite. Each apatite sample was characterized by its morphology, particle size, % CO3, zeta potential, and broadening of the (211), (112), (300), (202), and (002) diffraction maxima. Only the surface area/g and the X-ray powder diffraction line broadening showed a significant inverse correlation with hemolytic potential. These parameters were related to each other, and are indications of the degree of crystallinity.

Crystal-induced membranolysis of human red blood cells has been quantitated for calcium oxalate monohydrate and calcium oxalate dihydrate crystals. Calcium oxalate monohydrate crystals are significantly more membranolytic than calcium oxalate dihydrate crystals at constant surface area. If the crystal morphology of calcium oxalate monohydrate is altered by grinding, the lytic potential at constant surface area is markedly reduced. However, altered calcium oxalate dihydrate crystals are as lytic as natural calcium oxalate dihydrate crystals at constant surface area. Differences in the calcium oxalate monohydrate and dihydrate crystal structures, specifically the structural characteristics of the disordered water channel in calcium oxalate dihydrate, can explain these different membranolytic characteristics.

In studies of experimental Candida albicans infections, growth of invading organisms sometimes ceased before the organisms reached the neutrophil infiltrates. Lysates of human neutrophils inhibited the directed growth of candida pseudohyphae in agarose gel and suppressed the proliferation of candida yeast in broth cultures, but did not kill the organisms or prevent their germination. The growth-inhibitory material released from disrupted neutrophils had an estimated molecular weight of 30 kD and differed from most previously described neutrophil antimicrobial factors in that it was present in cell sap rather than granules, and did not appear in the supernatant after stimulation of the cells. Neutrophil death and dissolution may represent an alternative host defence mechanism against invasive C albicans infection.

Rat renal inner papillary collecting tubule cells (RPCT) have been isolated and maintained in primary culture. The cells have been found to be of only one type and they have maintained the characteristics of RPCT cells. The RPCT cells in culture appear as a monolayer with intermittent clumps of rounded cells. When small calcium oxalate monohydrate crystals (COM) or calcium oxalate dihydrate crystals (COD) are added to the monolayer of RPCT cells, the crystals bind on or about these clumps of rounded-up cells. The use of this system as a model for the study of crystal membrane interactions in crystalluria and urolithiasis is discussed.

In order to identify the physical and structural parameters that relate best to the membranolytic, inflammatory, and fibrotic potentials of different silicon dioxide (SiO2) and titanium dioxide (TiO2) crystals, we have studied the potential of four different SiO2 and two different TiO2 crystal structures to lyse human red blood cells and to induce pulmonary inflammation and fibrosis in mice. The crystals studied were quartz, tridymite, cristobalite, coesite, anatase, and rutile. Mice were injected intratracheally with each crystal at constant surface area. Inflammation and fibrosis were assessed 6 wk after crystal instillation by wet lung weight (lung index), protein concentration of lung lavage fluid, the level of hydroxyproline in the lung, and histologic examination. In vitro red blood cell (RBC) lysis was evaluated by incubating the crystals with 51Cr-labeled RBC and measuring the release of 51Cr into the medium. Known crystallographic data for each of the minerals were used to calculate the percent occupied volume. Biologic activity seemed to correlate with percent occupied volume, suggesting that surface molecular topology may be important in crystal-cell interactions. The crystals with more irregular surfaces and protruding oxygen atoms, which form surface pockets (quartz, tridymite, and cristobalite), showed a dramatic increase over saline controls for lung index (greater than 2 x), cell number and lavage protein concentration (greater than 4 x), and hydroxyproline level (greater than 2 x). The other more boxlike crystals (coesite, anatase, and rutile) displayed little change in these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

To assess the role of crystal size in biologic responses, we quantitated red blood cell lysis and lung inflammation and fibrosis in the mouse using 4 alpha-quartz preparations with average diameters of 1, 5, 7.8, and 11.2 microns. When compared on the basis of identical crystal surface areas, the 1-micron fraction was more hemolytic than the other 3 fractions. The three larger fractions had equivalent membranolytic activities. After 6 weeks of postintratracheal instillation of the crystals into mice, the 1-micron-diameter crystal fraction increased wet lung weights by 1.25 x that of saline controls, while a 1.75 x increase was found for the three larger crystal fractions. A similar response was found when evaluating fibrosis development by determining lung hydroxyproline levels. Measurement of the percentage of the crystal dose remaining in the lungs revealed that the biologic differences observed were not due to a difference in the clearance of the smaller crystal fraction. Thus, larger crystals of alpha-quartz produce a greater degree of inflammation and fibrosis when instilled into the lung than those of 1 micron diameter, even though the smaller crystals are more membranolytic in vitro and appear to be cleared from the lung at the same rate as the larger crystals.

As the roles of peptidic agents in therapy expand, the need for gaining the knowledge for formulating peptides and/or polypeptides becomes increasingly urgent. In an attempt to study various approaches to formulating peptidic agents for therapeutic applications, we investigated the interactions between drug carriers and peptides, using liposomes and insulin as a model. The fusion and aggregation properties of dipalmitoylphosphatidylcholine (DPPC) small, unilamellar liposomes, on the binding of insulin was studied by the techniques of resonance energy transfer of fluorescent labeled lipids, electron microscopy, and right-angle scattering. Within 1 h of adding insulin to DPPC liposomes at 25 degrees C, the average size of the liposomes increased from 239 to 361 A in diameter. There was no further increase in the size of the liposomes after the fused liposomes reached this size. However, the aggregation of the fused liposomes continued to increase for several hours after the insulin-induced fusion stopped. Our results suggest that insulin induces the aggregation of newly fused liposomes, when the temperature is below the gel----liquid crystalline phase-transition temperature (Tc) of the liposomes. The aggregation of fused liposomes is markedly affected by not only the zinc content of insulin but also the pH and ionic strength of the solution. The results of the present study demonstrate that an amphyphilic molecule, such as insulin, could induce the fusion of liposomes via hydrophobic interaction and facilitate liposome aggregation via hydrophilic interaction. Thus, when entrapping insulin by small, unilamellar liposomes, care should be taken to avoid fusion and aggregation.