Design and functional characterization of Salmo salar TLR5 agonist peptides derived from high mobility group B1 acidic tail

Toll-like receptor 5 (TLR5) responds to the monomeric form of flagellin and induces the MyD88-depending signaling pathway, activating proinflammatory transcription factors such as NF-κB and the consequent induction of cytokines. On the other hand, HMGB1 is a highly conserved non-histone chromosomal protein shown to interact with and activate TLR5. The present work aimed to design and characterize TLR5 agonist peptides derived from the acidic tail of Salmo salar HMGB1 based on the structural knowledge of the TLR5 surface using global molecular docking platforms. Peptide binding poses complexed on TLR5 ectodomain model from each algorithm were filtrated based on docking scoring functions and predicted theoretical binding affinity of the complex. Circular dichroism spectra were recorded for each peptide selected for synthesis. Only intrinsically disordered peptides (6W, 11W, and SsOri) were selected for experimental functional assay. The functional characterization of the peptides was performed by NF-κB activation assays, RT-qPCR gene expression assays, and Piscirickettsia salmonis challenge in SHK-1 cells. The 6W and 11W peptides increased the nuclear translation of p65 and phosphorylation. In addition, the peptides induced the expression of genes related to the TLR5 pathway activation, pro- and anti-inflammatory response, and differentiation and activation of T lymphocytes towards phenotypes such as TH1, TH17, and TH2. Finally, it was shown that the 11W peptide protects immune cells against infection with P. salmonis bacteria. Overall, the results indicate the usefulness of novel peptides as potential immunostimulants in salmonids.

The AO classification system for tibial plateau fractures: An independent inter and intraobserver agreement study

PURPOSE

Classifying tibial plateau fractures is paramount in determining treatment regimens and systemizing decision making. The original AO classification described by Müller in 1996 and the Schatzker classification of 1970 are the most cited classifications for tibial plateau fractures, demonstrating substantial to almost perfect agreement. The main problem with these classifications schemes is that they lack the detail required to convey the variety of fracture patterns encountered. In 2018, the AO foundation published a new classification system for proximal tibia fractures, highlighting a more complete and detailed number of categories and subcategories. We sought to independently determine inter and intraobserver agreement of the AO classification system, compared to the previous systems described by Müller and Schatzker.

METHODS

One hundred seven consecutive tibial plateau fractures were screened, and a representative data set of 69 was created. Six independent evaluators (three knee surgeons, three senior orthopedic residents) classified the fractures using the original AO, the Schatzker and the new AO classifications. After six weeks, the 69 cases were randomized and reclassified by all evaluators. The Kappa coefficient (k) was calculated for inter- and intraobserver correlation and is expressed with 95% confidence intervals.

RESULTS

interobserver agreement was moderate for all three classifications. k = 0.464 (0.383-0.560) for the original AO; k = 0.404 (0.337-0.489) for Schatzker; and k = 0.457 (0.371-0.545) for the base categories of the new AO classification. The inclusion of subcategories and letter modifiers to the new classification worsened agreement to k = 0.358 (0.302-0.423) and k = 0.174 (0.134-0.222), respectively. There were no significant differences between knee surgeons and residents for the new classification. Intra-observer correlation was also moderate for each of the scores: k = 0.630 (0.578-0.682) for the original AO; k = 0.623 (0.569-0.674) for Schatzker; and k = 0.621 (0.566-0.678) for the new AO base categories; without differences between knee surgeons or residents.

CONCLUSIONS

This study demonstrated an adequate inter and intra-observer agreement for the new AO tibial plateau fractures classification system for its base categories, but not at the subcategory or letter modifier levels.

Chitosan Microparticles Enhance the Intestinal Release and Immune Response of an Immune Stimulant Peptide in Oncorhynchus mykiss

The aquaculture industry is constantly increasing its fish production to provide enough products to maintain fish consumption worldwide. However, the increased production generates susceptibility to infectious diseases that cause losses of millions of dollars to the industry. Conventional treatments are based on antibiotics and antivirals to reduce the incidence of pathogens, but they have disadvantages, such as antibiotic resistance generation, antibiotic residues in fish, and environmental damage. Instead, functional foods with active compounds, especially antimicrobial peptides that allow the generation of prophylaxis against infections, provide an interesting alternative, but protection against gastric degradation is challenging. In this study, we evaluated a new immunomodulatory recombinant peptide, CATH-FLA, which is encapsulated in chitosan microparticles to avoid gastric degradation. The microparticles were prepared using a spray drying method. The peptide release from the microparticles was evaluated at gastric and intestinal pH, both in vitro and in vivo. Finally, the biological activity of the formulation was evaluated by measuring the expression of il-1β, il-8, ifn-γ, Ifn-α, and mx1 in the head kidney and intestinal tissues of rainbow trout (Oncorhynchus mykiss). The results showed that the chitosan microparticles protect the CATH-FLA recombinant peptide from gastric degradation, allowing its release in the intestinal portion of rainbow trout. The microparticle-protected CATH-FLA recombinant peptide increased the expression of il-1β, il-8, ifn-γ, ifn-α, and mx1 in the head kidney and intestine and improved the antiprotease activity in rainbow trout. These results suggest that the chitosan microparticle/CATH-FLA recombinant peptide could be a potential prophylactic alternative to conventional antibiotics for the treatment of infectious diseases in aquaculture.

New strategy for the design, production and pre-purification of chimeric peptide with immunomodulatory activity in Salmosalar

The intensive salmon farming is associated with massive outbreaks of infections. The use of antibiotics for their prevention and control is related to damage to the environment and human health. Antimicrobial peptides (AMPs) have been proposed as an alternative to the use of antibiotics for their antimicrobial and immunomodulatory activities. However, one of the main challenges for its massive clinical application is the high production cost and the complexity of chemical synthesis. Thus, recombinant DNA technology offers a more sustainable, scalable, and profitable option. In the present study, using an AMPs function prediction methodology, we designed a chimeric peptide consisting of sequences derived from cathelicidin fused with the immunomodulatory peptide derived from flagellin. The designed peptide, CATH-FLA was produced by recombinant expression using an easy pre-purification system. The chimeric peptide was able to induce IL-1β and IL-8 expression in Salmo salar head kidney leukocytes, and prevented Piscirickettsia salmonis-induced cytotoxicity in SHK-1 cells. These results suggest that pre-purification of a recombinant AMP-based chimeric peptide designed in silico allow obtaining a peptide with immunomodulatory activity in vitro. This could solve the main obstacle of AMPs for massive clinical applications.

Hip Fractures in the Elderly During the COVID-19 Pandemic: A Latin-American Perspective With a Minimum 90-Day Follow-Up

Introduction:

Hip fracture patients have been severely affected by the COVID-19 pandemic; however, the sub acute effects of a concomitant SARS-CoV-2 infection and the outcomes in highly exposed developing countries are still unknown. Our objective is to describe the morbidity and mortality of elderly patients admitted for a hip fracture during the COVID-19 pandemic in Chile, with a minimum 90-day follow-up. Also, to elucidate predictors for mortality and to compare mortality results with the pre-pandemic era.

Material and Methods:

Multicentric retrospective review of patients admitted for a fragility hip fracture in 3 hospitals during the COVID-19 pandemic, and during the same time in 2019. All clinical information and images were recorded, and patients were followed for a minimum of 90-days. Morbidity and mortality were the primary outcomes. Uni/multivariable models were performed to elucidate predictors for mortality utilizing the Weibull’s regression.

Results:

Three hundred ninety-one cases were included. From the 2020 cohort (162 patients), 24 (15%) had a concomitant SARS-CoV-2 infection. Fourteen patients (58%) tested positive after admission. The COVID-19(+) group had a higher risk of in-hospital, 30-day, and 90-day mortality (p < 0.001). They also had a prolonged hospital stay and presented with more complications and readmissions (p < 0.05). Only COVID-19(+) status and older age were independent predictors for mortality with a HR = 6.5 (p = < 0.001) and 1.09 (p = 0.001), respectively. The 2020 cohort had twice the risk of mortality with a HR = 2.04 (p = 0.002) compared to the 2019 cohort. However, comparing only the COVID-19 (-) patients, there was no difference in mortality risk, with a HR = 1.30 (p = 0.343).

Discussion:

The COVID-19 pandemic has significantly affected healthcare systems and elderly patients.

Conclusions:

Hip fracture patients with a concomitant SARS-CoV-2 virus infection were associated with increased morbidity and mortality throughout the first 3 months. COVID-19 status and older age were significant predictors for mortality. Efforts should be directed into nosocomial infection reduction and prompt surgical management.

Level of evidence:

Level III

The relationship between perceived social support and depressive symptoms in informal caregivers of community-dwelling older persons in Chile

AIM

Depression among caregivers of older persons is a serious concern, but it is often overlooked and neglected in developing countries. The aim of this study was to examine the relationship between perceived social support and depression in informal caregivers of community-dwelling older persons in Chile.

METHODS

We analyzed cross-sectional secondary data on 377 dyads of community-dwelling older persons and their informal caregivers from a nationwide survey in Chile. The Duke-UNC Functional Social Support Questionnaire (FSSQ) was used to measure caregivers' perceived social support, and the Center for Epidemiologic Studies Depression Scale assessed their depression.

RESULTS

In this study, 76.9% of the caregivers perceived a high level of social support, and 46.9% were assessed as having depression. Based on multivariable analysis, factors that decrease the likelihood of being depressed are a high level of social support (odds ratio (OR) = 0.311, 95% confidence interval (CI): 0.167-0.579) and having taken holidays in the past 12 months (OR = 0.513, 95%CI: 0.270-0.975). Factors that increase the likelihood of being depressed are being a female caregiver (OR = 2.296, 95%CI: 1.119-4.707), being uninsured (OR = 4.321, 95%CI: 1.750-10.672), being the partner or spouse of the care recipient (OR = 3.832, 95%CI: 1.546-9.493), and the number of hours of care (OR = 1.053, 95%CI: 1.021-1.085).

CONCLUSION

Higher levels of perceived social support and holidays were associated with lower levels of depression. However, being female, being the care recipient's partner or spouse, being uninsured, and having long care periods had detrimental effects. Interventions to preserve and enhance perceived social support could help improve depressive symptoms in informal caregivers. Additionally, support should be available to caregivers who are women, uninsured, and the care recipient's partner or spouse, as well as those who provide care for long hours, to ensure they have respite from their caregiving role.

LOX-1 activation by oxLDL triggers an epithelial mesenchymal transition and promotes tumorigenic potential in prostate cancer cells

Obesity is related to an increased risk of developing prostate cancer with high malignancy stages or metastasis. Recent results demonstrated that LOX-1, a receptor associated with obesity and atherosclerosis, is overexpressed in advanced and metastatic prostate cancer. Furthermore, high levels of oxLDL, the main ligand for LOX-1, have been found in patients with advanced prostate cancer. However, the role of LOX-1 in prostate cancer has not been unraveled completely yet. Here, we show that LOX-1 is overexpressed in prostate cancer cells and its activation by oxLDL promotes an epithelial to mesenchymal transition, through of lowered expression of epithelial markers (E-cadherin and plakoglobin) and an increased expression of mesenchymal markers (vimentin, N-cadherin, snail, slug, MMP-2 and MMP-9). Consequently, LOX-1 activation by oxLDL promotes actin cytoskeleton restructuration and MMP-2 and MMP-9 activity inducing prostate cancer cell invasion and migration. Additionally, LOX-1 increased the tumorigenic potential of prostate cancer cells and its expression was necessary for tumor growth in nude mice. In conclusion, our results suggest that oxLDL/LOX-1 could be ones of mechanisms that explain why obese patients with prostate cancer have an accelerated tumor progression and a greater probability of developing metastasis.

Thalidomide delayed the ability of 4T1 cells to amass into tumors in Balb/c mice

Thalidomide (Thal) can suppress the growth of established, as well as explanted tumors in mice. We wanted to determine if it could suppress the ability of tumor cells to assemble and establish a primary tumor at the injection site. Using the mouse 4T1 mammary tumor model, we fed Thal to mice for 4 days, then injected 10(5) 4T1 cells into the interscapular region of Balb/c mice. After 20 days on treatment with Thal, all seven control mice, fed with meal had tumors ranging from 3 to 93 mm(3) (median 20). Two of the eight mice fed with meal + Thal had no tumors, and the remaining mice had tumors ranging from 2 to 22 mm(3) (median 5). The median volume of the tumors in the control group was significantly more than that of mice treated with Thal (p = 0.03, Mann-Whitney test). In vitro treatment of the 4T1cells with Thal did not inhibit their ability to proliferate, to adhere to plastic, or to bind to Concanavalin-A. Thal caused a marked reduction in the ability of the 4T1 cells to assemble into palpable tumors.

Thalidomide inhibited the synthesis of IgM and IgG whereas Thalidomide+Dexamethasone and Dexamethasone alone acted as co-stimulants with pokeweed and enhanced their synthesis

Thalidomide (Thal) provides effective treatment for erythema nodosum leprosum (ENL). In combination with Dexamethasome (Dex) it is an effective treatment for multiple myeloma (MM) and Waldenström's macroglobulinemia (WM). Thal's mechanism(s) of action in the treatment of these diverse medical conditions is not known, but it could be suppression of immunoglobulin (Ig) synthesis. Mononuclear cells were stimulated with pokeweed (PWM), and treated with Thal, Thal+Dex or Dex. The cultures were assayed for IgM and IgG. The maximum synthesis was expected to occur in cultures stimulated with PWM at 0.5, 5.0 or 10 microg/ml. The test agents at 15 microM each were expected to alter the response. Compared to cultures stimulated with PWM alone, there was significantly less Ig in the cultures containing Thal+PWM, and significantly more Ig in the cultures containing Thal+Dex+PWM or Dex+PWM (Wilcoxon). The median % of maximum was 57 for cultures treated with Thal+PWM; 184 for cultures treated with Thal+Dex+PWM, and 139 for cultures treated with Dex+PWM. Thal also acted as a co-stimulant with PWM and enhanced the synthesis of IL-2, IL-6 and DNA; whereas, Thal+Dex or Dex enhanced Ig synthesis, but suppressed IL-2, IL-6 and cell proliferation. Thal's ability to suppress Ig may explain its activity in ENL, MM and WM. The enhancement of Ig by Dex does not help to explain a role for Dex alone or in combination with Thal for the treatment of MM and WM.

Thalidomide suppressed IL-1beta while enhancing TNF-alpha and IL-10, when cells in whole blood were stimulated with lipopolysaccharide

Thalidomide is used to treat erythema nodosum leprosum (ENL). The events that precipitate this inflammatory reaction, which may occur in multibacillary leprosy patients, and the mechanism by which thalidomide arrest ENL, are not known. Thalidomide's ability to inhibit tumor necrosis factor alpha (TNF-alpha) in vitro has been proposed as a partial explanation of its effective treatment of ENL. In in vitro assays, thalidomide can enhance or suppress TNF-alpha. This is dependent on the stimulant used to evoke TNF-alpha; the procedure used to isolate the mononuclear cells from blood, and the predominant mononuclear cell type in the culture. To avoid artifacts that may occur during isolation of mononuclear cells from blood, we stimulated normal human blood with LPS and evaluated the effect of thalidomide and dexamethasone on TNF-alpha, and other inflammatory cytokines and biomarkers. Thalidomide suppressed interleukin 1 beta (IL-1beta) (p = 0.007), and it enhanced TNF-alpha (p = 0.007) and interleukin 10 (IL-10) (p = 0.031). Dexamethasone enhanced IL-10 (p = 0.013) and suppressed IL-1beta, TNF-alpha, interleukin 6 (IL-6), and interleukin 8 (IL-8) (p = 0.013). The two drugs did not suppress: C-reactive protein (CRP), Ig-superfamily cell-adhesion molecule 1 (ICAM 1), tumor necrosis factor receptor 1 (TNFR1), tumor necrosis factor receptor 2 (TNFR2), or amyloid A. In vitro and in vivo evidence is accumulating that TNF-alpha is not the primary cytokine targeted by thalidomide in ENL and other inflammatory conditions.

Thalidomide suppressed interleukin-6 but not tumor necrosis factor-alpha in volunteers with experimental endotoxemia

An early rationale for using thalidomide to treat erythema nodosum leprosum had been based on some reports that it suppresses tumor necrosis factor-alpha (TNF-alpha). However, in vivo and in vitro studies have yielded variable results, having shown that thalidomide can either enhance or suppress TNF-alpha. Since the course of circulating cytokines like TNF-alpha after infusion of endotoxin into volunteers is reproducible and characteristic, we investigated the effect of thalidomide on endotoxin-induced synthesis of TNF-alpha, interleukin (IL)-6, and IL-8. The cytokine response from 18 placebo-treated subjects who had undergone the endotoxin challenge were pooled with a placebo-treated subject from the current study and were compared with 4 subjects who received thalidomide (100 mg) every 6 h for 5 doses before endotoxin challenge. Thirty minutes after the last dose of thalidomide or placebo, volunteers were infused with 4-ng/kg endotoxin. Plasma was collected and assayed for cytokines by enzyme-linked immunosorbent assay. Endotoxin evoked the synthesis of the cytokines in all volunteers. The peak response for TNF-alpha was 1.5 h, 2.5 h for IL-8, and 3.0 h for IL-6. Thalidomide did not significantly delay the release of cytokines into the circulating blood. At the peak response, thalidomide reduced the concentration of the cytokines in the plasma. Using the area under the dose response curve (AUC(0 to 24) h), thalidomide reduced the AUC for IL-6 by 56%, for IL-8 by 30%, and TNF-alpha by 32%. In this model, thalidomide did not suppress TNF-alpha or IL-8, but it did suppress IL-6 at 4-h postinfusion with lipopolysaccharide (P=0.004), at 6 h (P=0.014), at 12 h (P=0.001), and at 16 h (P=0.012).

Stabilization of red blood cell membranes by thalidomide in vitro

The anti-inflammatory effect of thalidomide has been well established. The mechanism of this anti-inflammatory action is still not completely understood. Certain drugs exert their anti-inflammatory action by stabilizing the membranes of polymorphonuclear neutrophils (PMN) thereby reducing the production of reactive oxygen intermediates. We evaluated the effect of thalidomide on cell membranes by using red blood cells (RBC), PMN and the monocyte-like cell line THP-1. Osmotic fragility of RBC showed that in vitro, thalidomide stabilized the membrane of RBC from plasma free blood; whereas, it did not affect RBCs from whole blood. Red blood cells taken from subjects before and after ingestion of thalidomide were not affected after exposure to different concentrations of hypotonic NaCl solution. Thalidomide did not affect the membrane stability of PMNs as well as THP-1 in a significant manner. These data suggest that the anti-inflammatory mechanism of thalidomide is not related to events associated with the oxidative burst of PMNs or monocytes.

Thalidomide does not modify the ability of cells in leprosy patients to incorporate [3H]-thymidine when incubated with M. leprae antigens

The immune response in reversal reaction, (RR) and in erythema nodosum leprosum (ENL) is characterized in vitro by an enhancement in lymphocyte blast transformation against M. leprae. As thalidomide is an effective treatment for ENL, this study assessed the effect of this drug on these phenomena. Mononuclear cells from patients attending the clinic at ALERT and from healthy staff were cultured for 5 days with integral M. leprae (IMl), or a modified Dharmendra antigen (Dhar), or PPD from M. tuberculosis. In one set of cultures, thalidomide was added once at the initiation of the culture; in the other set thalidomide was added a second time (2x), 18 h prior to harvesting the cells. The mononuclear cells, in the absence of thalidomide, from healthy staff, borderline tuberculoid patients (BT) and BT patients in RR (BT/RR) incorporated [3H]-thymidine best when cultured with PPD > Dhar > M. leprae. The cells from patients with ENL did not respond well to the M. leprae antigens. Thalidomide (2x) enhanced proliferation to Dhar in the BTRR group (Wilcoxon signed rank test, P < 0.05). No significant changes occurred for the other groups. Comparing PPD-stimulated cells treated with thalidomide once to those treated with thalidomide twice, thalidomide (2x) suppressed incorporation of [H3]-thymidine by the PPD-stimulated (P < 0.05) as well as IMl-stimulated (P < 0.05) cells in the healthy staff group. In the Dhar-stimulated cells from the healthy staff thalidomide significantly suppressed TNF-alpha (P < 0.05). A mixed effect was seen within and between the other groups, but there was a trend for thalidomide to suppress TNF-alpha induced by the M. leprae, Dhar and PPD antigens.

Suppressed ion chromatography for monitoring chemical impurities in steam for geothermal power plants

A suppressed ion chromatography (IC) technique has been evaluated as a chemical monitoring tool for detecting major anions (F-, Cl-, NO3- and SO4(2-)) of condensed steam in geothermal power plants. It is shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in the geothermal industry. An electrical conductivity detector (0.1 microS sensitivity) with an anion-exchange column (IonPac AS4A-SC), a micro-membrane suppressor (AMMS II), and an isocratic high-pressure pump system were successfully used for detecting low concentrations of inorganic anions. Method detection limits for the anions of interest were <0.184 mg/L. Details of the IC methodology as well as some experimental results obtained during its application for the chemical monitoring of geothermal steam pipes are also described.

Thalidomide's ability to augment the synthesis of IL-2 in vitro in HIV-infected patients is associated with the percentage of CD4+ cells in their blood

Thalidomide is used for treating erythema nodosum leprosum. It is also used to treat aphthous ulcers in HIV-infected patients. The mechanism of action of this drug is yet to be fully understood, but modulation of inflammatory cytokines like IL-2 and TNF-alpha may play a role. We investigated the effect of thalidomide on the production of IL-2 and TNF-alpha by staphylococcal enterotoxin A (SEA) stimulated peripheral blood mononuclear cells (PBMC) from HIV-infected patients. The PBMC from 20 patients was incubated in the presence of 4.0 microg/ml of thalidomide and 50 ng/ml of SEA. After 18 h, the culture supernatant was assayed for IL-2 and TNF-alpha. The PBMC incubated with thalidomide and SEA produced significantly more IL-2 than those incubated with SEA alone. The TNF-alpha secreted by the same cells incubated with thalidomide and SEA was not significantly different from that secreted by the cells incubated with SEA alone. The amount of IL-2 produced in the thalidomide and SEA treated cultures was directly correlated with the percentage of CD4+ cells in blood, and inversely correlated with the percentage of CD8+ cells in blood. No statistically significant correlations were found when comparing the amount of TNF-alpha produced in the thalidomide and SEA treated cultures with the percentage of CD4+ or CD8+ cells in the blood. Thalidomide can act, in vitro, as an additional stimulant to augment the synthesis of IL-2 in HIV-infected patients. Increased production of IL-2 by activated T-cells may be a mechanism through which it exerts its immunomodulatory effects.

Synthesis and release of ATP by soluble mitochondrial F1 in complex with its inhibitor protein during dimethylsulfoxide-water transitions

Soluble mitochondrial F1 and F1 in complex with the natural ATPase inhibitor protein (F1-IP) catalyze the spontaneous synthesis of [gamma-32P]ATP from medium [32P]phosphate and enzyme-bound ADP when incubated in media with dimethylsulfoxide (Me2SO); under these conditions, the synthesized [gamma-32P]ATP is not released into the media, it remains tightly bound to the enzymes [Gómez-Puyou, A., Tuena de Gómez-Puyou, M. & de Meis, L. (1986) Eur. J. Biochem. 159, 133-140]. Some of the characteristics of the synthesized [gamma-32P]ATP were studied in F1 and F1-IP (ATPase activities of 70 and 1-3 micromol x min(-1) x mg(-1), respectively). In Me2SO media, gamma-phosphate of synthesized ATP in F1 or F1-IP exchanges with medium phosphate. From the rates of the exchange reaction, the half-times for hydrolysis of the synthesized ATP in F1 and F1-IP were calculated: 45 min and 58 min for F1 and F1-IP, respectively. The course that synthesized [gamma-32P]ATP follows after dilution of the Me2SO synthetic mixture with aqueous buffer was determined. After dilution, the half-life of synthesized ATP in F1 was less than 1 min. In F1-IP, ATP was also hydrolyzed, but at significantly lower rates. In F1-IP, dilution also produced release of the synthesized [gamma-32P]ATP. This was assayed by the accessibility of [gamma-32P]ATP to hexokinase. About 25% of [gamma-32P]ATP synthesized in F1-IP, but not in F1, was released into the media after dilution with aqueous buffer that contained 20 mM phosphate. Release of tightly bound ATP required the binding energy of phosphate and solvation of F1-IP, however, the particular kinetics of F1-IP were also central for medium ATP synthesis in the absence of electrochemical H+ gradients.

Ultrastructural changes of tissues produced by inhalation of thinner in rats

Thinner is a substance that is used for industrial purposes and for drug abuse; addiction is of young people (average age, 7.5 years). Although the health problem of voluntary or nonvoluntary solvent sniffing is important, great attention has been paid to the epidemiology and pharmacology of paint thinner or industrial solvents inhalation, but studies at the morphological and biochemical level are scarce. This work describes the morphological changes in the lung, liver, kidney, adrenal glands, and central nervous system induced by short- (up to 4 weeks) and long-term (up to 14 weeks) periods of thinner inhalation in rats.

Hydrolysis of thalidomide abrogates its ability to enhance mononuclear cell synthesis of IL-2 as well as its ability to suppress the synthesis of TNF-alpha

Thalidomide is effective in the treatment of inflammatory conditions like erythema nodosum leprosum in leprosy patients, and aphthous ulcers in AIDS patients. Its mechanism of action is uncertain and reports of its effect on the synthesis of inflammatory cytokines such as IL-2 and TNF-alpha are contradictory. As thalidomide is labile to spontaneous hydrolysis at pH 7.4, studies were carried out to explore the effects of deliberate hydrolysis or the ability of thalidomide to modulated cytokine production by human mononuclear cells stimulated in vitro with Staphylococcal enterotoxin A (SEA)(IL-2) or lipopolysaccharide from Salmonella minnesota (LPS)(TNF-alpha). Unhydrolyzed thalidomide at 4.0 micrograms/ml consistently enhanced the synthesis of IL-2 in SEA-stimulated cells, and suppressed the synthesis of TNF-alpha in LPS-stimulated cells; whereas, hydrolyzed thalidomide had no enhancing effect on SEA stimulated-cell synthesis of IL-2 or suppressive effect on LPS stimulated-cell synthesis of TNF-alpha. These findings demonstrate that thalidomide's ability in vitro to enhance IL-2 and to suppress TNF-alpha in stimulated cells is dependent on the intact molecule and underscore the necessity to employ thalidomide under appropriate physicochemical conditions.

Immunomodulatory assays to study structure-activity relationships of thalidomide

Thalidomide, which has a long history of tragedy because of its ability to cause severe birth defects, is very effective in alleviating erythema nodosum leprosum in leprosy patients and aphthous ulcers in AIDS patients. The causes of these inflammatory diseases and the mechanism by which thalidomide diminishes them are unknown. It has been suggested that modulation of the immune response plays an important role. We found that thalidomide exerts immunomodulatory activity in three bioassays. It suppresses an IgM plaque forming cell response in mice injected with sheep erythrocytes: it inhibits TNF-alpha production by LPS stimulated human mononuclear cells: and it enhances IL-2 production by Con-A stimulated human mononuclear cells. We employed these bioassays to compare the activity of 15 analogs of thalidomide with thalidomide itself. Eight of the compounds were derivatives of the glutarimide moiety of thalidomide and the others were phthalimide or derivatives of the phthalimide moiety of thalidomide. N-hydroxyphthalimide, a simple derivative of phthalimide, was more effective than thalidomide and was also the most effective of the compounds assayed in suppressing the IgM plaque and TNF-alpha responses, but it did not enhance the IL-2 response, instead, it significantly suppressed it.

Thalidomide can be either agonistic or antagonistic to LPS evoked synthesis of TNF-alpha by mononuclear cells

The effect if thalidomide on tumor necrosis factor alpha (TNF-alpha) produced in vitro by lipopolysaccharide (LPS) stimulated human cells was investigated. In cultures of LPS stimulated human mononuclear cells enriched for adherent cells and in cultures of LPS stimulated human monocytes of the cell line-THP-1, thalidomide enhanced the synthesis of TNF-alpha. When cultures of unfractionated peripheral blood mononuclear cells were stimulated with LPS, thalidomide decreased the synthesis of TNF-alpha. Depending on the type of cells stimulated with LPS in vitro, thalidomide, at concentrations achieved in vivo, can either enhance or suppress the synthesis of TNF-alpha.

Thalidomide increases the synthesis of IL-2 in cultures of human mononuclear cells stimulated with Concanavalin-A, Staphylococcal enterotoxin A, and purified protein derivative

Thalidomide significantly increases the quantity of extracellular IL-2 in cultures of human mononuclear cells stimulated with mitogens or antigen. Cells from 7 donors exposed for 2 h to 4.0 micrograms/ml of thalidomide and stimulated for 16-18 h with 20 micrograms/ml of Concanavalin-A (Con-A) averaged producing 187 +/- 49% more IL-2 than cells stimulated with Con-A alone. In similar experimental procedures and comparisons the pg/ml of IL-2 secreted by thalidomide-treated cells from five donors stimulated with 50 ng/ml of Staphylococcal enterotoxin A (SEA) increased by 159 +/- 32%, and the pg/ml of IL-2 secreted by thalidomide-treated cells from 2 donors stimulated with 5.0 micrograms/ml of purified protein derivative of Mycobacterium tuberculosis increased by 120 +/- 4%. Thalidomide also significantly increases the quantity of intracellular IL-2 in cells stimulated with mitogens. Cells exposed to thalidomide and stimulated with Con-A had an increase in intracellular IL-2 of 130% after 8 h and 157% after 12 h in culture; cells stimulated with SEA had an increase in intracellular IL-2 of 120% after 8 h and 182% after 12 h in culture. Thalidomide did not alter the percent of lymphocytes expressing the alpha-chain of IL-2 receptor, nor did it significantly increase incorporation of [3H]thymidine by cells.

Synthesis of medium pyrophosphate by soluble mitochondrial F1 through dimethyl sulfoxide-water transitions

Soluble F1 from heart mitochondria incubated in mixtures that have Mg2+, inorganic phosphate, and dimethyl sulfoxide (40% (v/v)) catalyzes the spontaneous synthesis of ATP and pyrophosphate (Tuena de Gómez-Puyou, M., García, J. J., and Gómez-Puyou, A. (1993) Biochemistry 32, 2213-2218). By filtration techniques, it was determined that synthesized ATP and pyrophosphate are enzyme bound, albeit the affinity for pyrophosphate was lower than that of ATP. After ATP and pyrophosphate were formed in dimethyl sulfoxide mixtures, dilution with aqueous buffer to a dimethyl sulfoxide concentration of 6.0% brought about the partition of pyrophosphate into the media. This was evidenced by filtration experiments as well as by the accessibility of synthesized pyrophosphate to soluble inorganic pyrophosphatase. Release of pyrophosphate induced by dilution occurred in less than 15 s. Under conditions that produce release of pyrophosphate, no release of ATP was observed; instead, ATP underwent hydrolysis. Studies on the effect of arsenate on the synthesis and hydrolysis of ATP and PPi in F1 showed that hydrolysis of synthesized PPi at its site of synthesis was slower than that of ATP. Thus, the question of whether differences in the rates of hydrolysis accounted for the dilution-induced release of PPi but not of ATP was addressed. Synthesis and hydrolysis of ATP and pyrophosphate were examined in preparations of soluble F1 in complex with its inhibitor protein; the complex had an ATPase activity about 100 times lower than that of free F1. In mixtures that contained dimethyl sulfoxide, the complex synthesized ATP and pyrophosphate at nearly the same rates; upon dilution, hydrolysis of both compounds occurred also at similar rates, yet only pyrophosphate was released. The same phenomenon was observed in F1 that had been depleted of adenine nucleotides. Hence, dilution-induced release of PPi was independent of the overall catalytic properties of the enzyme or its content of adenine nucleotides. Since synthesis of ATP occurs at the expense of the ADP that remains after depletion of adenine nucleotides, it is likely that the failure of ATP to be released is due to the high affinity that F1 exhibits for the synthesized ATP. Nevertheless, the results illustrate that a complete catalytic cycle that starts with medium Pi and ends with medium pyrophosphate may be reproduced in soluble mitochondrial F1.

An anatomical and biochemical study of the pituitary proopiomelanocortin systems in the polypteriform fish Calamoichthys calabaricus

Immunohistochemical and biochemical analyses were performed on the pituitary Proopiomelanocortin (POMC) systems of the polypteriform fish Calamoichthys calabaricus. Immunohistochemical staining of the pituitary revealed a clustering of ACTH immunopositive cells within the rostral pars distalis. alpha-Melanocyte stimulating hormone (alpha-MSH)-related and beta-endorphin-related immunoreactivity were found colocalized in epithelial cells of the pars intermedia. Biochemical analyses included Sephadex G-50 column chromatography, reversed-phase HPLC, and cation exchange chromatography. These analyses revealed the presence of immunoreactive forms of ACTH which stimulated glucocorticoid release when tested on isolated Bufo marinus adrenocortical tissue. Three forms of alpha-MSH were detected, and the major form had the same HPLC chromatographic properties as synthetic monoacetylated alpha-MSH. Finally, five forms of beta-endorphin were detected, and all of these forms were N-acetylated. Based on these observations, it appears that N-acetylation is a major post-translational processing event within the melanotropic cells of C. calabaricus. Given the position of Order Cladistia in the phylogeny of actinopterygian fish, it appears that N-acetylation of POMC-related products is an ancestral trait of osteichthyean fish.

The action of the sesquiterpenic benzoquinone, perezone, on electron transport in biological membranes

Perezone (2-(1,5-dimethyl-4-hexenyl)-3-hydroxymethyl-p-benzoquinone) is a sesquiterpenic benzoquinone isolated from roots of plants of the genus Perezia. It exhibits oxido-reduction characteristics which suggest that the compound can be used for studies of the electron transfer chain of rat liver mitochondria. Perezone at 50 microM inhibits mitochondrial electron transport through a process which differs from that of rotenone, amytal, and Antimycin A. The inhibition is temperature dependent; at 35 degrees C it fails to inhibit valinomycin-induced mitochondrial respiration, but at 20 degrees C it inhibits respiration by 80-90%. Perezone is an electron-donor and electron-acceptor compound that behaves similarly to naphtoquinone. It mediates electron transport from a reaction center preparation isolated from Rhodopseudomonas sphaeroides and added cytochrome c. The low respiration of rat liver mitochondria depleted of coenzyme Q10 (CoQ) is increased by perezone. The electron transport activity of perezone was also demonstrated with CoQ-deficient yeast mutant E3-24.

On the mechanism of action of polyether XXVIII at site I of the electron-transfer chain in rat liver mitochondria

In rat liver mitochondria, the macrocyclic polyether, dibenzo-18-crown-6 (polyether XXVIII) inhibits the oxidation of NAD-dependent substrates, as stimulated by ADP, uncouplers and valinomycin plus K+. It does not inhibit the oxidation of succinate. It is concluded that polyether XXVIII inhibits electron transfer in the NADH-CoQ span of respiratory chain. This is a process that is reversed by menadione. Inhibition of oxidation of NAD-dependent substrates in K+-depleted mitochondria induced by the polyether is reversed by concentrations of K+ higher than 60 mM, and also by Li+, a cation that does not complex with polyether XXVIII. As assayed by swelling mitochondria, reversal of the inhibition of electron transfer is accompanied by influx of monovalent cations. Polyether XXVIII also inhibits in submitochondrial particles the aerobic oxidation of NADH, but not that of succinate; this inhibition is also reversed by K+ at high concentrations, and Li+. The data are consistent with the hypothesis that a monovalent cation is required for maximal rates of electron transport in the NADH-CoQ span of the respiratory chain.