Changes In Spleen Weight Research Articles

The Impact of Aging and Toll-like Receptor 2 Deficiency on the Clinical Outcomes of Staphylococcus aureus Bacteremia.

Staphylococcus aureus (S. aureus) causes a broad range of infections. Toll-like receptor (TLR) 2 senses the S. aureus lipoproteins in S. aureus infections. Aging raises the risk of infection. Our aim was to understand how aging and TLR2 affect the clinical outcomes of S. aureus bacteremia. Four groups of mice (wild type/young, wild type/old, TLR2-/-/young, and TLR2-/-/old) were intravenously infected with S. aureus, and the infection course was followed. Both TLR2 deficiency and aging enhanced the susceptibility to disease. Increased age was the main contributing factor for increased mortality rates and changes in spleen weight, whereas other clinical parameters, such as weight loss and kidney abscess formation, were more TLR2 dependent. Importantly, aging increased mortality rates without relying on TLR2. In vitro, both aging and TLR2 deficiency down-regulated cytokine/chemokine production of immune cells with distinct patterns. In summary, we demonstrate that aging and TLR2 deficiency impair the immune response to S. aureus bacteremia in distinct ways.

Pilot Study: Nutritional and Preclinical Safety Investigation of Fermented Hispidin-Enriched Sanghuangporus sanghuang Mycelia: A Promising Functional Food Material to Improve Sleep.

Sleep disturbances have been the hallmark of the recent coronavirus disease 2019 pandemic. Studies have shown that once sleep is disrupted, it can lead to psychological and physical health issues which can, in turn, disrupt circadian rhythm and induce further sleep disruption. As consumers are trying to establish healthy routines, nutritional and preclinical safety investigation of fermented hispidin-enriched Sanghuangporus sanghuang mycelia (GKSS) as a novel food material for spontaneous sleep in Sprague-Dawley rats is conducted for the first time. Results showed that the nutritional analysis of GKSS including moisture, ash, crude lipid, crude protein, carbohydrate, and energy were found to be 2.4 ± 0.3%, 8.0 ± 2.5%, 1.7 ± 0.3%, 22.9 ± 1.2%, 65.1 ± 3.1%, and 367.1 ± 10.2 kcal/100 g respectively. In the 28-day repeated-dose oral toxicity study, only Sprague-Dawley male rats receiving 5 g/kg showed a slight decrease in feed consumption at week 3, but no associated clinical signs of toxicity or significant weight loss were observed. Although a significant reduction of the platelet count was found in mid- and high-dose GKSS treated male groups, such changes were noted to be within the normal range and were not correlated with relative spleen weight changes. Hence, the no observed adverse effect level (NOAEL) of GKSS was identified to be higher than 5 g/kg in rats. After the safety of GKSS is confirmed, the sleep-promoting effect of GKSS ethanolic extract enriched with hispidin was further assessed. Despite 75 mg/kg of GKSS ethanolic extract does not affect wakefulness, rapid eye movement (REM) sleep and non-REM (NREM) sleep, GKSS ethanolic extract at 150 mg/kg significantly decreased wakefulness and enhanced NREM and REM sleep. Interestingly, such effects seem to be mediated through anti-inflammatory activities via NF-E2-related factor-2 (Nrf2) signaling pathway. Taken together, these findings provide the preliminary evidence to studies support the claims suggesting that GKSS contained useful phytochemical hispidin could be considered as and is safe to use as a functional food agent or nutraceutical for relieving sleep problems mediated by Nrf2 pathway, which the results are useful for future clinical pilot study.

NCOA4 Acts in Hepatocytes to Regulate Ferritin Subunit Levels and Hepatic Iron Storage

The intracellular protein nuclear receptor coactivator 4 (NCOA4) has been shown to mediate the degradation of the iron storage protein ferritin (Mancias et al., Nature 2014; Dowdle et al., Nat Cell Biol 2014). Accordingly, mice with global disruption of Ncoa4 show ferritin accumulation in multiple organs (Bellelli R et al., Cell Rep 2016). How NCOA4 activity in different tissues contributes to local and systemic iron homeostasis, however, has not yet been clearly defined. Here we selectively dissect the role of NCOA4 in the liver, the body's major iron depot.To facilitate targeted Ncoa4 knockdown in hepatocytes, we utilized Ncoa4 -targeting siRNA that was conjugated to triantennary N-acetylgalactosamine (GalNAc- Ncoa4 siRNA) to promote uptake by the hepatocyte asialoglycoprotein receptor. We first validated the ability of GalNAc- Ncoa4 siRNA treatment to target endogenous murine Ncoa4 mRNA for degradation in murine Hepa1-6 hepatoma cells. We next assessed the ability of GalNAc- Ncoa4 siRNA to acutely lower Ncoa4 expression in mouse liver. Eight-week-old C57BL/6N female mice were injected subcutaneously with 1, 3, or 5 mg/kg body weight of a sterile, endotoxin-tested solution of GalNAc- Ncoa4 siRNA in saline or with vehicle (saline) alone, and tissues were collected for analysis 24 hrs after injection. Compared to vehicle alone, GalNAc- Ncoa4 siRNA effectively lowered Ncoa4 expression in total liver RNA; because the degree of Ncoa4 knockdown that was achieved by the 3 mg/kg and 5 mg/kg doses was similar, the 3mg/kg dose was selected for our further experiments to reduce the possibility of off-target effects.We next examined the durability of hepatocyte Ncoa4 knockdown achieved by a single injection of GalNAc -Ncoa4 siRNA as well as the resulting effects on hepatic and systemic iron parameters. Eight-week-old C57BL/6N female mice were injected once with GalNAc- Ncoa4 siRNA or saline vehicle, and blood and tissues were collected for analysis at 1, 2, 3, or 4 weeks after injection. Compared to saline treatment, a single injection of GalNAc -Ncoa4 siRNA produced a significant, sustained reduction in hepatic Ncoa4 mRNA; Ncoa4 mRNA remained maximally suppressed at the 1, 2, and 3-week timepoints and began to rise slightly 4 weeks after injection. Saline-treated mice showed a slight, progressive increase in mean liver non-heme iron concentration (LIC) over the 4 weeks following injection, consistent with the known effect of age on murine hepatic iron stores. However, in mice injected with a single dose of GalNAc- Ncoa4 siRNA, the rise in LIC over the 4-week time period was significantly greater, consistent with increased hepatic iron storage. Immunoblotting of liver lysates revealed that levels of the ferritin heavy (FTH) and light (FTL) subunits increased in mice treated with GalNAc- Ncoa4 siRNA compared to saline-treated controls. These increases in FTH and FTL were evident 1 week after GalNAc- Ncoa4 siRNA injection, and FTH and FTL levels continued to rise with additional weeks of Ncoa4 knockdown. In mice treated with saline, spleen non-heme iron concentration (SIC) increased over the 4 weeks following injection, consistent with the known effect of age on murine splenic iron stores. However, at the 3 and 4-week time points, mice treated with GalNAc- Ncoa4 siRNA showed a significant reduction in SIC compared to saline-treated controls, which correlated histologically with reduced iron retention in splenic macrophages. Compared to saline treatment, GalNAc -Ncoa4 siRNAtreatment did not produce significant changes in spleen weight, serum iron, complete blood count, or non-heme iron concentration of heart, pancreas, or muscle.Collectively, our findings indicate that NCOA4 acts in hepatocytes to limit LIC as well as hepatic levels of FTH and FTL. Furthermore, local NCOA4 activity in hepatocytes impacts iron distribution to the spleen. Our results are compatible with a model in which degradation of the ferritin protein complex in hepatocytes occurs as a constitutive process that is mediated by NCOA4. Importantly, our findings demonstrate that in the setting of hepatocyte Ncoa4 knockdown, other cellular pathways cannot compensate to maintain normal LIC and normal hepatic levels of FTH and FTL. Additionally, our findings raise the possibility that enhancement of NCOA4 activity in hepatocytes might serve as a therapeutic approach to promote hepatic iron mobilization in iron overload disorders. DisclosuresNo relevant conflicts of interest to declare.

Changes in the immune system in experimental acanthamoebiasis in immunocompetent and immunosuppressed hosts

BackgroundAcanthamoebiasis is most often found in patients with immune deficiency, with infections facilitated by the intake of immunosuppressive drugs. The host immune response to Acanthamoeba spp. infection is poorly understood. Thus, in this study, we aimed to examine the course of Acanthamoeba spp. infection taking into account the host’s immunological status, including assessment of the hematological parameters, cytokine analysis, immunophenotypic changes in spleen populations, and histological spleen changes, which could help clarify some aspects of the immune response to acanthamoebiasis. In our experimental study, we used Acanthamoeba strain AM 22 isolated from the bronchoaspirate of a patient with acute myeloid leukaemia (AML) and atypical pneumonia symptoms.ResultsAcanthamoeba spp. affected the hematological parameters in immunocompetent and immunosuppressed mice and induced a change in spleen weight during infection. Moreover, analysis of anti-inflammatory (IL-4 and IL-10) and pro-inflammatory (IL-17A and IFN-γ) cytokines produced by splenocytes stimulated with concanavalin A demonstrated that Acanthamoeba spp. induced a selective Th1, Th2 and Th17 response at later stages of the infection in immunocompetent hosts. In the case of hosts with low immunity, Acanthamoeba elicited robust Th1 cell-mediated immunity without the participation of Th17. We observed suppression of CD8+ and CD4+ T lymphocytes and CD3+CD4-CD8- double-negative (DN) T lymphocyte populations in the beginning, and in the case of CD3+/CD4+/CD8+ double-positive (DP) T cells in the final phase of Acanthamoeba spp. infection in hosts with low immunity. Also, CD4+T lymphocytes and CD3+/CD4+ and CD3+/CD8+ lymphocyte counts during each stage of acanthamoebiasis were shown to be upregulated.ConclusionsWe demonstrated that analysis of the immune response and pathogenesis mechanisms of clinical isolates of Acanthamoeba spp. in an animal model not only has purely cognitive significance but above all, may help in the development of effective methods of pharmacological therapy especially in patients with low immunity.

Environmentally Relevant Chronic Low-Dose Tritium and Gamma Exposures do not Increase Somatic Intrachromosomal Recombination in pKZ1 Mouse Spleen.

The toxicity of tritium is a public health concern given its presence and mobility in the environment. For risk predictions using radiological protection models, it is essential to allocate an appropriate radiation weighting factor (WR). This in turn should be consistent with the observed relative biological effectiveness (RBE) of tritium beta radiation. Although the International Commission on Radiological Protection (ICRP) currently recommends a WR of 1 for the calculation of committed effective dose for X rays, gamma rays and electrons of all energies, including tritium energies, there are concerns that tritium health risks are underestimated and that current regulatory tritium drinking water standards need revision. In this study, we investigated potential cytotoxic and genotoxic effects in mouse spleen after one month and eight months of chronic exposure to low-dose tritiated water (HTO). The dose regimes studied were designed to mimic human chronic consumption of HTO at levels of 10 kBq/l, 1 MBq/l and 20 MBq/l. The total doses from these radiation exposures ranged from 0.01 to 180 mGy. We also compared the biological effects of exposure to HTO with equivalent exposure to external whole-body 60Co gamma rays. Changes in spleen weight and somatic intrachromosomal recombination (DNA inversions) in spleen tissue of pKZ1Tg/+ mice were monitored. Our results showed no overall changes in either spleen organ weights and no increase mouse splenic intrachromosomal recombination frequencies, indicating that current drinking water standards for tritium exposure in the form of HTO are likely to be adequately protective against cytotoxic and genotoxic damage in spleen. These results demonstrate no evidence for cytotoxicity or genotoxicity in mouse spleen following chronic exposures to HTO activities (or equivalent gamma doses) up to 20 MBq/L.

Characterization of the immune response in male and female mice following lipopolysaccharide‐induced systemic inflammation (1096.10)

Intraperitoneal injection of lipopolysaccharide (LPS) is a common method to induce systemic inflammation, but there is wide variability in the doses given and no standardized measure of inflammatory level. We characterized the inflammatory response in adult male and female C57BL/6 mice following 3 LPS exposure protocols by measuring body weight changes, spleen weight and immune cell composition in the blood using flow cytometry. Mice were injected twice a week for 1 month with either a 200 μL dose of saline or a low dose of LPS (7.5 x 10^4 EU/kg). Half the animals in each condition were injected with a high dose of LPS (7.5 X 10^5 EU/kg) the day before sacrifice. Acute exposure to a high dose of LPS caused a 10.6% decrease in body weight overnight and no significant change in spleen weight. White blood cell and lymphocyte counts decreased and toll‐like receptor 4 (TLR4) positive macrophage count increased for both males and females. Exposure to 1 month of low LPS caused no change in the immune cell composition in the blood and body weight, but spleen weights were significantly increased compared to saline animals. 1 month of low LPS followed by high LPS caused an even greater increase in spleen weight than the 1 month low LPS condition, but no other changes. In summary, all 3 LPS exposure protocols led to evidence of an immune response in both sexes, but body weight and blood immune cell composition normalized following chronic low LPS exposure.Grant Funding Source: Supported by a CSUPERB New Investigator Award (KAW)

Altered Inflammatory Responses to Citrobacter rodentium Infection, but not Bacterial Lipopolysaccharide, in Mice Lacking the Cyp4a10 or Cyp4a14 Genes

Murine hepatic Cyp4a mRNAs are markedly downregulated during inflammation. Here, we investigated the roles of Cyp4a10 and Cyp4a14 in the response to infection with C. rodentium. Absence of either Cyp4a gene attenuated or abrogated the changes in spleen weight, colon crypt length, hepatic cytokine, and acute phase protein mRNAs, and serum acute phase proteins and cytokines caused by infection. Cyp4a10(-/-) mice on a low-salt diet had a similar hepatic acute phase response as those mice on a high-salt diet, suggesting that hypertension associated with this genotype is not the cause of their altered inflammatory response. In contrast, wild-type, Cyp4a10(-/-), and Cyp4a14(-/-) mice showed similar responses to injected LPS. These results implicate Cyp4a10 and Cyp4a14 in the regulation of the host inflammatory response to enteropathogenic bacterial infection but not to acute aseptic inflammation. Understanding the mechanism of this role may lead to novel therapeutic approaches in some inflammatory diseases.

Synthesis and Antitumor Activity of Ellagic Acid Peracetate

Ellagic acid (1) was synthesized for the first time from methyl gallate through 3-pentagalloylglucose (α-PGG), and ellagic acid peracetate (3,4,3',4'-tetra-O-acetylellagic acid, 2) was derived from 1 by acetylation. Oral administration of 2 suppressed melanoma growth significantly in C7BL/6 immunocompetent mice without having any effect on natural killer (NK) cell activity. Comparison of the immunoenhancing activities of 1 and 2 indicated that the latter compound increased white blood cell quantities in peripheral blood and immune cells enriched from the bone marrow and liver of mice. Therefore, both the antitumor efficacy and the immunity enhancement by 2 were greater than those by 1. In addition, on oral administration neither 1 nor 2 resulted in whole body, liver, or spleen weight changes of normal, tumor-free mice, indicating that these compounds are potentially non-toxic to mice. It was shown that ellagic acid peracetate (2) inhibits B16 melanoma cell growth in vitro, and induces B16 cell apoptosis, corresponding to BCL-2 down-regulation. Collectively, the present data imply that 2 can suppress tumor growth by enhancing mouse immunity and inducing tumor cell apoptosis without apparent side effects.

A measure of glucocorticoid load provided by DNA methylation of Fkbp5 in mice

Given the contribution of cortisol dysregulation to neuropsychiatric and metabolic disorders, it is important to be able to accurately compute glucocorticoid burden, a measure of allostatic load. One major problem in calculating cortisol burden is that existing measures reflect cortisol exposure over a short duration and have not been proven to reliably quantify cortisol burden over weeks or months. We treated two cohorts of mice with corticosterone in the drinking water and determined the relationship between serial plasma corticosterone levels drawn over 4 weeks and the whole-blood DNA methylation (DNAm) changes in a specific glucocorticoid-sensitive gene, Fkbp5, determined at the end of the treatment period. We observed that the percent reduction in DNAm in the intron 1 region of Fkbp5 determined from a single blood draw strongly reflected average glucocorticoid burden generated weekly during the prior month of glucocorticoid exposure. There were also strong correlations in DNAm with glucocorticoid-induced end organ changes in spleen weight and visceral fat. We tested a subset of these animals for anxiety-like behavior in the elevated plus maze and found that DNAm in the blood also has predictive value in determining the behavioral consequences of glucocorticoid exposure. A whole-blood assessment of Fkbp5 gene methylation is a biomarker that integrates 4 weeks of glucocorticoid exposure and may be a useful measure in states of excess exposure. It will be important to determine if Fkbp5 DNAm changes can also be a biomarker of glucocorticoid burden during chronic social stress.

DRDE-07 and its analogues as promising cytoprotectants to nitrogen mustard (HN-2)—An alkylating anticancer and chemical warfare agent

Nitrogen mustard (HN-2), also known as mechlorethamine, is an alkylating anticancer agent as well as blister inducing chemical warfare agent. We evaluated the cytoprotective efficacy of amifostine, DRDE-07 and their analogues, and other antidotes of mustard agents against HN-2. Administration of 1 LD(50) of HN-2 (20mg/kg) percutaneously, decreased WBC count from 24h onwards. Liver glutathione (GSH) level decreased prominently and the maximum depletion was observed on 7th day post-HN-2 administration. Oxidised glutathione (GSSG) level increased significantly at 24h post-administration and subsequently showed a progressive decrease. Hepatic malondialdehyde (MDA) level and percent DNA damage increased progressively following HN-2 administration. The spleen weight decreased progressively and reached a minimum on 3-4 days with subsequent increase. The antidotes were administered repeatedly for 4 and 8 days after percutaneous administration of single sublethal dose (0.5 and 0.25 LD(50)) of HN-2. Treatment with DRDE-07, DRDE-30 and DRDE-35 significantly protected the changes in spleen weight, WBC count, GSH, GSSG, MDA and DNA damage following HN-2 administration (0.5 and 0.25 LD(50)). There was no alteration in the transaminases (AST and ALT), and alkaline phosphatase (ALP) activities, neither with HN-2 nor with antidotes. The present study shows that HN-2 is highly toxic by percutaneous route and DRDE-07, DRDE-30 and DRDE-35 can partially protect it.

Adaptogenic effect of Bacopa monniera (Brahmi)

As stress is linked to many diseases, research on an effective antistress agent (adaptogen) from plants has gained importance. We report the investigations on the adaptogenic property of a standardized extract of Bacopa monniera against acute (AS) and chronic stress (CS) models in rats. Panax root powder ( Panax quinquefolium) was taken as a standard. Male SD rats, weighing 180–200 g, exposed to immobilization stress for 150 min once only for AS and for seven consecutive days in CS, were fed with B. monniera or Panax root powder daily for 3 days in AS and for 7 days in CS, 45 min prior to each exposure of stress. Rats were sacrificed immediately after stress, the blood was collected, and the plasma was separated out for biochemical estimation. Adrenals, spleen, and thymus were dissected for organ weight and stomach for ulcer score. AS exposure significantly increased the ulcer index, adrenal gland weight, plasma glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatine kinase (CK) but significantly decreased the spleen weight. Pretreatment with B. monniera at 40 mg/kg po significantly reduced the AS-induced increase in the ulcer index, adrenal gland weight, plasma glucose, AST, and CK. A dose of 80 mg/kg po significantly reversed the AS-induced changes in adrenal gland weight, spleen weight, plasma glucose, ALT, and AST. Panax root powder, 100 mg/kg po, significantly reversed the AS-induced changes in spleen weight, plasma ALT, AST, and CK. CS exposure resulted in a significant increase in the ulcer index, adrenal gland weight, plasma AST, and CK with a significant decrease in the thymus and spleen weight, plasma triglyceride, and cholesterol. Pretreatment with low dose of B. monniera extract at 40 mg/kg significantly reversed changes in ulcer index and plasma AST only, whereas the pretreatment with higher dose significantly reversed CS-induced changes in ulcer index, adrenal gland weight, CK, and AST. Panax root powder significantly reversed CS-induced increase in ulcer index, adrenal gland weight, CK, and AST. On the basis of our result, it is concluded that the standardized extract of B. monniera possesses a potent adaptogenic activity.

Immunotoxicity of a standardized citrus polymethoxylated flavone extract

Polymethoxylated flavones (PMFs) from citrus inhibit production of TNF-α and other pro-inflammatory cytokines. As TNF-α also modulates NK cell activity, the current studies were conducted to assess the potential for a standardized citrus PMF mixture to suppress humoral and innate immune functions. PMFs were isolated from orange peel oil using a procedure that obtained a consistent mixture of PMFs both in identity and proportion. The mixture consisted of nobiletin (30.7%), 3,3′,4′,5,6,7,8-heptamethoxyflavone (27.9%), trimethylscutellarein (14.5%), tangeretin (10.4%), sinensetin (5.8%), 5-demethyl-nobiletin (2.0%), hexa- O-methylquercetagetin (1.3%), 5-demethyl-tetramethylscutellarein (0.6%), and other flavonoids (2.7%). To assess the effect of the PMF mixture on humoral immune responses, female B 6C 3F 1 mice ( n=8) were exposed to the PMF by gavage at 5, 50, 150 and 500 mg/kg/day for 28 days. On day 25, mice were sensitized to sRBC by tail vein injection and AFC response determined 4 days later. Humoral immunity was insensitive to suppression following exposure to all concentrations of the PMF mixture. Suppression of NK cell activity was observed only following 500 mg/kg/day for 28 days. Body weights were not affected by exposure to any concentration of the PMF mixture in sRBC immunized or non-immunized mice. However, in sRBC-immunized mice, higher concentrations of PMF were associated with a statistically insignificant increase in spleen weight ( P>0.05). No change in spleen weight was observed in non-immunized mice. As anticipated, based on previously published in vitro observations, long-term, high-dose exposure to a standardized mixture of citrus PMFs caused a mild suppression of NK cell activity; however, humoral immunity was not sensitive to suppression at the same exposure levels.

Immunomodulatory properties of Mycoplasma pulmonis: I. Characterization of the immunomodulatory activity

For many years, it has been recognized that Mycoplasma infection affects the host's immune system in different ways. In this work, experiments were performed to characterize the influence of Mycoplasma pulmonis infection on various immunological parameters and to follow the kinetics of their variations. A Balb/c mouse model was used to assess hematological evaluations, changes in spleen weight, antibody responses against sheep erythrocytes, neutrophil phagocytosis, colloidal carbon clearance, and anti- Mycoplasma antibody responses. At the hematological level, infected animals were found to have significantly increased total lymphocyte and polymorphonuclear leukocyte counts and an augmentation in spleen weight. Seven days after Mycoplasma infection, antibody responses against sheep erythrocytes were considerably diminished, and at days 7 and 14 after infection, phagocytic activity was also reduced. After 1 week of infection, the colloidal carbon clearance pattern was decreased, and during the whole infectious process, anti- Mycoplasma antibody titers were found to be low. Results from this part of research show a persistent infection that does not resolve in a short period, which is associated with a general dysfunction in the immune system and poor immune responses against several different antigens.

Alterations in sympathetic innervation of thymus and spleen in aged mice

Aging is associated with reduced immune reactivity, contributing to increased rates of infectious disease and cancer in old age. We have begun to assess the potential for sympathetic nervous system involvement in age-related immune dysfunction by characterizing sympathetic noradrenergic (NA) innervation in lymphoid organs in old animals. In the present study noradrenergic innervation of spleen and thymus was examined histologically and neurochemically in 2-, 12- and 24-month old BALB/c mice. In the thymus of 2-month old animals, NA nerve fibers were found in the subcapsular, cortical, and cortico–medullary regions associated with blood vessels and septa; occasional branches from these nerve fibers entered the parenchyma. With increasing age and thymic involution, NA nerve fibers increased in density; by 24 months of age, dense plexuses were compacted among septa and blood vessels, and numerous linear, varicose nerve fibers were observed branching into the parenchyma. Thymic norepinephrine (NE) concentration (per mg wet weight) increased approximately 4-fold in 12-month old animals and 15-fold in 24-month old animals. Taking the reduced thymus weight into account, total thymic NE at 12- and 24-month of age was equivalent to total thymic NE at 2-month of age, suggesting that NA innervation is maintained as the thymus involutes. In the spleen from 2-month old animals, NA innervation entered the white pulp with the central artery to innervate the periarteriolar lymphatic sheath and the marginal zone. At 12-month of age, histologically and neurochemically there was no change in splenic NA innervation. By 24-month of age, NE was increased significantly, independent of changes in spleen weight. Histologically, increased catecholamine-containing fibers were apparent at 24-month of age, particularly in the parenchyma surrounding the central artery. The alterations in sympathetic NA innervation of lymphoid organs with age suggest that the sympathetic nervous system and NE may play a role in age-associated immune dysregulation. Alternatively, the changes in NA innervation may be secondary to functional changes within the immune system.

The effects and molar potency of iloprost, U46619 and sodium nitroprusside on capsular and vascular smooth muscle of the isolated perfused canine spleen

The isolated canine spleen was perfused at constant flow with continuous recording of splenic arterial perfusion pressure (SAPP) and spleen weight. Intra-arterial injections of the thromboxane A 2 (TXA 2) mimetic U46619 caused dose-related increases in splenic arterial perfusion pressure (SAPP) of short duration (ED 50 0.31 nmol). There were very small changes in spleen weight accompanying any of the vasoconstrictor responses to U46619. The stable analogue of prostacyclin, iloprost, caused dose-dependent reductions in SAPP (ED 50 1.3 nmol) indicating vasodilatation. There were no changes in spleen weight to any doses of iloprost indicating a lack of action on capsular smooth muscle. Similarly, the nitric oxide (NO) mimetic sodium nitroprusside caused dose-related reductions in SAPP of short duration (ED 50 5.8 nmol). No changes in spleen weight accompanied splenic vasodilator responses to any dose of sodium nitroprusside (SNP). The results indicate the potential actions and intrinsic potency of three endogenous vasoactive substances and provide information about their relative roles in the control of the splenic microcirculation in situations when they are released.

Studies on the myelosuppressive activity of doxorubicin entrapped in liposomes

The myelosuppressive activity of doxorubicin encapsulated in liposomes of differing lipid composition and size was quantified in mice by measurement of changes in spleen weight, peripheral white blood cells (WBC), and bone marrow nucleated cells. Following i.v. administration of free doxorubicin at a dose of 20 mg/kg, a 90% reduction in marrow cellularity was observed on day 3. The marrow nucleated cell count was similar to control values by day 7. Administration of an equivalent dose of doxorubicin that was encapsulated in large (diameter, approximately 1.0 microns) egg phosphatidylcholine/cholesterol (EPC/Chol)(molar ratio, 55:45) liposomes induced an 80% reduction in bone marrow cellularity that lasted for periods of greater than 7 days. Similar results were obtained following administration of large (1.0 microns) liposomal doxorubicin systems formulated with distearoylphosphatidylcholine/cholesterol (DSPC/Chol) (molar ratio 55:45). In contrast, liposomal doxorubicin prepared using small (diameter, approximately 0.1 micron) DSPC/Chol liposomes induced only a 40% reduction (day 3) in bone marrow cellularity, which returned to control values by day 7. Other indicators of doxorubicin-mediated myelosuppressive activity (spleen weight loss and peripheral leukopenia) correlated well with changes observed in marrow cellularity. An exception to this, however, was observed in animals treated with small (0.1 -micron) DSPC/Chol Liposomal doxorubicin, which displayed peripheral leukopenia for periods of greater than 14 days. This extended leukopenia was not observed following administration of small (0.1 -micron) EPC/Chol liposomal doxorubicin. Marrow-associated liposomal lipid and doxorubicin were quantified to determine if the extent of doxorubicin-mediated myeloid toxicity could be correlated to changes in biodistribution of the entrapped drug. It was demonstrated that 10-20 times more doxorubicin is delivered to the bone marrow when the drug is given encapsulated in large liposomes than when it is associated with small liposomes. These data are useful in defining characteristics of liposomal preparations that modulate the myelosuppressive behaviour of entrapped antineoplastic agents.

Ligula intestinalis (L.) (Cestoda: Pseudophyllidea): plerocercoid‐induced changes in the spleen and pronephros of roach, Rutilus rutilus (L.), and gudgeon, Gobio gobio (L.)

The effects of the plerocercoid of Ligula intestinalis (L.) (Cestoda: Pseudophyllidea) on the major lymphoid organs, the spleen and pronephros, of roach, Rutilus rutilus (L.), and gudgeon, Gobio gobio (L.), are described. The spleen of ligulosed roach showed a significant decrease in weight. Differential cell counts suggested this was due to a reduction in erythrocytes, despite significant increases in macrophages and vacuolated granulocytes. The spleen of gudgeon, which consisted almost entirely of erythrocytes, showed a slight reduction in weight in ligulosed fish. In both roach and gudgeon this decrease was independent of parasite burden. Differential cell counts of the pronephros from ligulosed roach revealed a significant decrease in neutrophils and increase in vacuolated granulocytes. In the pronephros of gudgeon, however, cell counts were unaffected by ligulosis. Ultrastructural observations included an apparent disintegration of vacuolated granulocytes and increased pinocytic activity in specialized endothelial cells in the spleens of ligulosed roach. Also, melano‐macrophage centres and melano‐macrophages increased in the spleen of ligulosed roach and gudgeon, respectively. The marked changes in spleen weight and differential cell counts in ligulosed roach and lack of such changes in ligulosed gudgeon correlate with the differential response to the parasite by these two fish species.

Splenic hypertrophy and extramedullary hematopoiesis induced in male Syrian hamsters by short photoperiod or melatonin injections and reversed by melatonin pellets or pinealectomy.

Adult male Syrian hamsters either placed in a short photoperiod alone or kept in a long photoperiod and given daily afternoon injections of the pineal indole melatonin (25 micrograms) exhibited splenic hypertrophy and extramedullary hematopoiesis in addition to a marked regression in testicular weight. The testicular regression as well as the changes in spleen weight and histology could be prevented if the animals in short photoperiod were either pinealectomized or implanted subcutaneously with a pellet containing 1 mg melatonin. Female Syrian hamsters given afternoon injections of melatonin for 7 or 12 weeks had ovaries devoid of corpora lutea; additionally, these animals had reduced relative spleen weights compared to the control animals. In conclusion, it is apparent that spleen weight varies with the functional status of the gonads. Splenic hypertrophy accompanied by pineal-induced testicular regression in males may be related to splenic extramedullary hematopoiesis.

Modification of radiation-induced spleen weight changes in mice by 2-mercaptopropionylglycine.

It was found that the MPG partially protects the spleen against weight loss due to radiation, and exaggerates the compensatory reaction in the tissue during recovery. It is also concluded that MPG protects the stem cells in the spleen, which helps to restore the peripheral blood by extramedullary erythropoiesis.

The course of a Plasmodium berghei infection in six different mouse strains

Experiments were carried out to study common and strain specific features of malaria (P. berghei) in mice. In the various mouse strains infection with 105 P.E. results in four different mortality patterns, with frequent secondary infections among all long surviving mice. A prepatent period of four days, proliferation in oxyphilic erythrocytes, a first peak of parasitaemia on day 7/8 and crisis occur in all strains. The magnitude of peak parasitaemia, however, and the ability to develop polychromatocytosis which coincides with survival beyond crisis are strain specific. Transient variations in number of erythrocytes and s.g.o.t. activity shortly after infection are the earliest noticeable changes, but do not predict later ones. The inception of definitive anaemia is on day 6 in all strains, and thus just before the first peak of parasitaemia but independent of its magnitude. Anaemia further develops at a strain specific rate. In general, parasite proliferation, peak infection, crisis, and polychromatocytosis are followed by changes in s.g.o.t. activity chronologically but not quantitatively. Extensive thymic involution occurs in all strains, but develops in a strain specific pattern. Initial changes in spleen weight can reflect R.E.S. activity and an ongoing immunological process which collapses, however, around peak infection. Subsequent increases in spleen weight may in particular depend on proliferation of erythropoietic tissue, especially in instances of distinct polychromatocytosis. There is no quantitative correlation between changes in liver weight and s.g.o.t. activity, but focal liver cell necrosis may account for high s.g.o.t. activity.