Biomedical subjects

R Rossi

Publications and source records attributed to R Rossi.

At least 91 records · Page 5Linked to original sources

PubMed2001

Effects of light physical exercise on sleep regulation in rats.

PURPOSE: Acute physical exercise is known to enhance slow-wave sleep (SWS) and reduce paradoxical sleep (PS) in humans. In this study, we examined the effects of moderate physical exercise on sleep in rats. METHOD: Young adult Wistar rats underwent a 4-h baseline electroencephalographic (EEG) recording session. The following day, they were induced to walk (0.8 m x min(-1)) or run (4 m x min(-1)) for 45 min in a rota-rod treadmill. Active control rats (ACR) were placed on the locked rota-rod for 45 min, whereas passive control rats (PCR) remained in their home cages. They were then left free to sleep for 4 h during which EEG activity was recorded. Rectal temperature (Tre) was monitored before and after exercise in ACR, walking and running rats (WR and RR, respectively) and at 45 min intervals in PCR. RESULTS: WR were able to walk for 45 min consecutively whereas in RR performances differed. Posttraining Tre was unchanged in ACR, PCR, and WR and resulted about 1.8 degrees C above baseline in RR. In both WR and RR after exercise i) length of SWS and PS, ii) intensity of SWS (spectral power density in 1-4 Hz range), and iii) propensity for falling asleep were enhanced. Interestingly, there was a more conspicuous increment in PS than SWS. In ACR and PCR there were no changes in sleep. CONCLUSIONS: Due to the complexity of sleep regulation, the interaction of several factors might underlie the observed increment in SWS and PS. Nevertheless, it is interesting that light physical exercise favors sleep and above all a harmonic enhancement of both sleep phases.

Animals↗

PubMed2001

Response to caffeine and ryanodine receptor isoforms in mouse skeletal muscles.

The response to caffeine was studied in mouse muscles [diaphragm, soleus, and extensor digitorum longus (EDL)] with different ryanodine receptor isoform (RyR1, RyR3) composition and in single permeabilized muscle fibers dissected from diaphragm of wild-type (WT) and RyR3-deficient (RyR3-/-) mice at 1, 15, 30, and 60 postnatal days (PND). The caffeine response decreased during development, and, in adult mice, was greater in diaphragm, lower in EDL, and intermediate in soleus. This suggests a direct relation between response to caffeine and RyR3 expression. The lack of RyR3 reduced caffeine response in young, but not in adult mice, and did not abolish the age-dependent variation and the intermuscle differences. In diaphragm single fibers, the response to caffeine increased during development and was reduced in fibers lacking RyR3 both at 15 and 60 PND. A population of fibers highly responsive to caffeine was present in adult WT and disappeared in RyR3-/-. The results confirm the contribution of RyR3 to calcium release for contractile response and clarify the contribution of RyR3 to developmental changes and intermuscle differences.

Aging↗

PubMed2001

Topical 5-aminolevulinic acid and photodynamic therapy in dermatology: a minireview.

Photodynamic therapy (PDT) is a treatment modality using a photosensitizer, light and oxygen to cause photochemically induced selective cell death. When exposed to light with the proper wavelength, the topically applied photosensitizer or photosensitizer precursor can activate a biomolecule through electron transfer to yield free radicals or produce singlet oxygen from energy transferred from the excited sensitizer to molecular oxygen. The tissue damage is the result of the activation of reactive singlet oxygen or free radical production. Photodynamic therapy with topical application of 5-aminolevulinic acid (ALA) is a new technique and although it remains largely experimental, it has potential application for treatment of malignant skin tumors, various precancerous and selected benign skin diseases. This technique yields not only a high percentage of good therapeutic results but also excellent cosmetic outcome. This paper reviews the recently published data on clinical ALA-based PDT in dermatology.

Administration, Topical↗

PubMed2001

Somatostatin receptor subtypes 2 and 5 differentially affect proliferation in vitro of the human medullary thyroid carcinoma cell line tt.

Somatostatin and its receptors (SSTR1 to SSTR5) are expressed in normal human parafollicular C cells and medullary thyroid carcinoma (MTC), but the role of SSTR subtypes in cell growth regulation is still not clear. The present study demonstrates that the human MTC cell line TT stably expresses all the SSTR subtypes and responds to SSTR2 and SSTR5 activation by subtype-selective agonists with two different patterns in terms of [(3)H]thymidine ([(3)H]thy) incorporation and cell number. The SSTR2 preferential agonists (BIM-23120, BIM-23197, BIM-23190, and BIM-23014; 10(-9)-10(-6) M), significantly suppressed [(3)H]thy incorporation (58-13%) and reduced cell proliferation (50-28%), whereas the SSTR5-selective agonist, BIM-23206 (10(-9)-10(-6) M), significantly increased [(3)H]thy incorporation in TT cells (80-175%), but failed to influence cell proliferation. SSTR2 antagonist (BIM-23627) counteracted the action of SSTR2 preferential agonists on TT cells. Furthermore, increasing concentrations of SSTR5-selective agonists, BIM-23206, dose-dependently prevented the suppression of TT cell [(3)H]thy incorporation and proliferation produced by SSTR2 preferential agonist, BIM-23120, showing an antagonism between these compounds. The following conclusions were reached: 1) the human MTC cell line TT expresses all SSTR subtypes; 2) SSTR2 activation inhibits DNA synthesis and cell proliferation, whereas SSTR5 activation increases DNA synthesis; and 3) SSTR2 preferential agonist (BIM-23120) can antagonise SSTR5-selective agonist (BIM-23206) action and vice versa. These findings suggest a tissue-specific function and a tissue-specific interaction between the two receptors.

Carcinoma, Medullary↗

PubMed2001

Plasma endothelin-1 and big endothelin-1 levels in superior and inferior vena cava during protracted antiorthostatic hypokinetic/hypodynamia in rats.

The plasma levels of endothelin-1 and big endothelin-1 were evaluated in blood of rats in the superior and inferior vena cava, in normal posture (synchronous controls), and after 12 days head-down suspension and 1 day recovery in normal posture. In synchronous controls, the mean plasma concentration of endothelin-1 in inferior vena cava or superior vena cava was almost the same (5.89+/-0.63 pmol/l and 5.67+/-0.64 pmol/l, respectively), whereas the mean plasma concentration of big endothelin-1 was higher (p<0.05) in superior vena cava compared to inferior vena cava (5.49+/-0.75 pmol/l and 1.39+/-0.15 pmol/l, respectively). In samples from superior vena cava of head-down suspended rats big endothelin-1 levels were significantly lower (p<0.05) up to day 9 of suspension, compared to non-suspended synchronous controls, whereas endothelin-1 values were higher (p<0.05). Big endothelin-1 concentration was higher (p<0.05) in inferior vena cava compared to non-suspended synchronous controls. The behaviour of endothelin-1 was more complex, endothelin-1 levels were lower (p<0.05) on day 1 of head-down suspension and higher (p<0.05) in samples taken on days 9 and 12. After 1 day recovery endothelin-1 and big endothelin-1 concentrations returned to normal in both superior vena cava and inferior vena cava. These data indicate that the endothelial system involvement for the two venous beds is different and suggest that local rather than systemic evaluation could better explain endothelial involvement and the contribution of different anatomic sites to the biosynthesis, conversion and clearance of the various involved molecules.

Animals↗

PubMed2001

Bone loss determined by quantitative ultrasonometry correlates inversely with disease activity in patients with endogenous glucocorticoid excess due to adrenal mass.

OBJECTIVE: Glucocorticoid excess is widely recognized as one of the most important causes of bone loss. The mechanism of glucocorticoid-induced osteoporosis is presumably multifactorial, and consists of the loss of organic and non-organic compounds. Efforts have been made to develop simple physical methods for the assessment of bone tissue for the screening of subjects at high risk of osteoporosis, without the use of radioactive sources or ionizing radiation. Quantitative ultrasonometry (QUS) has been suggested as a useful method for monitoring patients undergoing glucocorticoid therapy, which is the most common cause of glucocorticoid excess. QUS appears to detect more structural bone changes than the traditional methods and allows assessment of bone density and elasticity, both characteristics influenced by organic and non-organic bone compounds. However, the use of QUS has not yet been extensively investigated in subjects with endogenous cortisol excess. The aim of this study was to evaluate the usefulness and predictive power of QUS in assessing bone loss in subjects with differing degrees of endogenous cortisol excess due to adrenal mass. DESIGN: Thirty-four patients (20 women and 14 men) aged between 21 and 59 years were evaluated; fifteen (9 women and 6 men; median age, 42 years) were affected by overt Cushing's syndrome (CS) and nineteen (11 women and 8 men; median age, 44 years) by subclinical CS, defined as lacking clinical signs of hormone excess despite the presence of at least two abnormalities in hypothalamic-pituitary-adrenal axis function, as assessed by routine endocrine tests. All women included were eumenorrhoic. METHODS: QUS measurement of amplitude-dependent speed of sound was performed on the 2nd to 5th proximal phalanges of the non-dominant hand using a DBM Sonic 1200R bone profiler (Igea S.r.l, Italy). The results were compared with bone density assessed on lumbar vertebrae (L1-L4) and femoral neck sites by dual-energy X-ray absorptiometry (DEXA). RESULTS: A strongly significant bone loss was detected by finger QUS measurement when the patients were considered either all together or as two subgroups (P<0.001, all). The bone density decrease in the fingers was similar to that found at the lumbar spine and femoral neck by the DEXA technique. Lumbar and finger Z-scores correlated inversely with 24 h urinary free cortisol (UFF) excretion (P<0.01, both). Finger Z-scores also correlated inversely with the estimated duration of subclinical CS (P<0.05). Concerning disease activity, only UFF was confirmed by multivariate analysis to be an independent factor influencing bone loss (P<0.05). A positive correlation between the results of the two techniques was found in controls (P<0.05) but not in patients. The lack of correlation between the two techniques in patients can probably be attributed to the different parameters of bone alteration measured by the techniques. CONCLUSIONS: The detection of bone loss in subclinical CS similar to that in overt CS suggests that all subjects with endogenous cortisol excess should be evaluated for bone mass. QUS measurement appears to be a reliable, radiation-free, simple and fast tool for the identification of bone alteration in subjects with endogenous cortisol excess.

Absorptiometry, Photon↗

PubMed2001

The simplified papilla preservation flap in the regenerative treatment of deep intrabony defects: clinical outcomes and postoperative morbidity.

BACKGROUND: The aims of the present multi-center, randomized, controlled clinical trial were: 1) to compare the efficacy of the simplified papilla preservation flap with and without a barrier membrane in deep intrabony defects; 2) to evaluate the postoperative morbidity and surgical complications; and 3) to preliminarily test the impact of baseline tooth mobility on clinical outcomes. METHODS: This parallel group, randomized, multi-center, controlled clinical trial involved 112 patients in 8 periodontal practices in 4 countries. A deep intrabony defect in each patient was accessed with the simplified papilla preservation flap. In the test defects, a bioabsorbable membrane was positioned. Patients' experiences with the surgical procedure and postoperative period were evaluated with a questionnaire. Clinical outcomes included clinical attachment level (CAL) and probing depth (PD) changes. RESULTS: Complete observations were available for 55 test and 54 control defects. CAL gains at 1 year were 3.5 +/- 2.1 mm in the guided tissue regeneration (GTR) group and 2.6 +/- 1.8 mm in the control group (P = 0.0117). CAL gains > or = 4 mm were observed in 50.9% of GTR sites and 33.3% of control sites. A significant center effect of 2.1 mm was observed (P= 0.01). Initial PD (P= 0.01) and baseline tooth mobility (P= 0.036) were significant covariates. During the procedure, 30.4% of test and 28.6% of controls reported feeling moderate pain, and subjects estimated the hardship of the procedure at 24 +/- 25 visual analog scale (VAS) units in the test group, and at 22 +/- 23 VAS in controls. In terms of the investigated outcomes, differences between test and control groups were not statistically significant. Among the postoperative complications, edema was most prevalent at week 1, and more frequently associated with the test treatment (P= 0.01). In the test group, 53.6% of membranes were exposed at week 3. CONCLUSIONS: The present study further supports the added benefits of guided tissue regeneration with respect to access flap alone in the treatment of deep intrabony defects, as well as the general efficacy of GTR in different clinical settings. Furthermore, our study indicates a possible influence of baseline tooth mobility on clinical outcomes.

Absorbable Implants↗

PubMed2001

Zinc status in athletes: relation to diet and exercise.

Zinc is involved in the biochemical processes supporting life, such as cellular respiration, DNA reproduction, maintenance of cell membrane integrity and free radical scavenging. Zinc is required for the activity of more than 300 enzymes, covering all 6 classes of enzyme activity. Zinc binding sites in proteins are often of distorted tetrahedral or trigonal bipyramidal geometry, made up of the sulphur of cysteine, the nitrogen of histidine or the oxygen of aspartate and glutamate, or a combination. Zinc in proteins can either participate directly in chemical catalysis or be important for maintaining protein structure and stability. The nutritional habits of elite athletes during training and competition are quite different from the recommended diet in the majority of the population. Endurance athletes often adopt an unusual diet in an attempt to enhance performance: an excessive increase in carbohydrates and low intake of proteins and fat may lead to suboptimal zinc intake in 90% of athletes. Mild zinc deficiency is difficult to detect because of the lack of definitive indicators of zinc status. In athletes, zinc deficiency can lead to anorexia, significant loss in bodyweight, latent fatigue with decreased endurance and a risk of osteoporosis.

Absorption↗

PubMed2001

[Hemorrhage caused by the rupture of a pancreatic pseudoaneurysm. Case report].

We report a 52 year old man with a pancreatic pseudocyst, that was admitted with severe abdominal pain, severe vomiting, fever and malaise. The clinical picture was considered secondary to a pseudocyst infection and the patient was operated, draining the infected cyst performing a necrosis surgery and pancreatojejunostomy. Forty eight hours after the operation, an ostomy bleeding was detected. A upper mesenteric artery angiography showed two pseudoaneurysms in the gastroduodenal artery, that were embolized. Bleeding stopped initially, but seven days later, it reappeared. The patient was subjected to an emergency pancreatoduodenectomy. Postoperative evolution was uneventful and the patient was discharged two weeks later. Spontaneous bleeding of pseudoaneurysms secondary to chronic pancreatitis is a complication with a 15 to 40% mortality that must be bore in mind.

Aneurysm, False↗

PubMed2001

[Metachronous pancreatic metastasis of a renal cell carcinoma. 3 new cases].

We report two males and one female, aged 71, 81 and 73 years old respectively, previously operated of a renal cell carcinoma. During the follow up of the 71 years old male, the CAT scan showed three lesions in the pancreas. Also, the CAT scan in the female showed one lesion in the tail of the pancreas. The 81 years old male was admitted to the emergency room due to a upper gastrointestinal bleeding. Endoscopy showed a proliferating lesion in the second portion of the duodenum whose biopsy showed a clear cell carcinoma. The CAT scan showed also a tumoral mass in the head of the pancreas. All three patients were subjected to surgical resection of the tumors without postoperative complications or mortality.

Aged↗

PubMed2001

Physical exercise intensity can be related to plasma glutathione levels.

The aim of the present study was to examine the effect of different kinds of physical exercise on plasma glutathione levels. Male Wistar rats were randomly divided into four groups: In walking group (W; n=6), rats were trained to walk 0.8 m/min for 45 min; slow running group (SR; n=6) were trained to run 4 m/min for 45 min; fast running group (FR; n=6) ran 8 m/min for 60 min and control rats (C; n=6) remained in their home cages. All animals were sacrificed after exercise and the levels of reduced glutathione (GSH) in plasma samples determined by high performance liquid chromatography (HPLC) with a fluorescent detector. Compared to controls, exercise did not change GSH plasma levels of the W group. A tendency to decrease blood GSH was observed in plasma samples of the SR group and in the FR group, physical exercise resulted in a dramatic decrease in GSH plasma levels. These data suggest that during light physical exercise there is a low production of reactive oxygen species (ROS) with a low request for antioxidant defence such as oxidation of GSH. The dramatic decrease observed in GSH levels in FR rats would indicate the presence of oxidative stress able to modify blood antioxidant profiles. Our results suggest that GSH plays a central antioxidant role in blood during intensive physical exercise and that its modifications are closely related to exercise intensity.

Animals↗

PubMed2001

Physical exercise intensity can be related to plasma glutathione levels.

The aim of the present study was to examine the effect of different kinds of physical exercise on plasma glutathione levels. Male Wistar rats were randomly divided into four groups: In walking group (W; n=6), rats were trained to walk 0.8 m/min for 45 min; slow running group (SR; n=6) were trained to run 4 m/min for 45 min; fast running group (FR; n=6) ran 8m/min for 60 min and control rats (C; n=6) remained in their home cages. All animals were sacrificed after exercise and the levels of reduced glutathione (GSH) in plasma samples determined by high performance liquid chromatography (HPLC) with a fluorescent detector. Compared to controls, exercise did not change GSH plasma levels of the W group. A tendency to decrease blood GSH was observed in plasma samples of the SR group and in the FR group, physical exercise resulted in a dramatic decrease in GSH plasma levels. These data suggest that during light physical exercise there is a low production of reactive oxygen species (ROS) with a low request for antioxidant defence such as oxidation of GSH. The dramatic decrease observed in GSH levels in FR rats would indicate the presence of oxidative stress able to modify blood antioxidant profiles. Our results suggest that GSH plays a central antioxidant role in blood during intensive physical exercise and that its modifications are closely related to exercise intensity.

Animals↗

PubMed2001

Serum thyroglobulin concentrations and (131)I whole-body scan results in patients with differentiated thyroid carcinoma after administration of recombinant human thyroid-stimulating hormone.

UNLABELLED: The use of recombinant human thyroid-stimulating hormone (rhTSH) has recently become available as an alternative diagnostic tool to assess the persistence and recurrence of differentiated thyroid carcinoma (DTC) in patients on thyroid hormone-suppressive therapy (THST) after near-total or total thyroidectomy and ablative doses of (131)I. We report the results of rhTSH administration in patients who were monitored for DTC. METHODS: Thirty-three adult DTC patients (13 men, 20 women; mean age +/- SE, 45.6 +/- 2.31 y; age range, 21-65 y) underwent diagnostic follow-up after rhTSH administration at a dose of 0.9 mg once a day for 2 d. Whole-body scanning and serum thyroglobulin (Tg) measurement were performed after rhTSH administration. Patients were divided into 2 groups depending on serum Tg concentrations on THST: 29 patients had Tg concentrations of <2 ng/mL (group A) and 4 patients had Tg values of >2 ng/mL (group B). RESULTS: In group A, Tg values remained at <2 ng/mL in 25 patients and increased from 1.1 +/- 0.14 ng/mL to 22.0 +/- 5.75 ng/mL (mean +/- SE) in 4 patients after rhTSH administration. Whole-body scanning did not reveal any uptake of (131)I in the 25 patients without an increase in Tg, whereas (131)I uptake was evident in 2 of the 4 patients with a rise in Tg. In group B, Tg values increased in all 4 patients from 17.3 +/- 6.35 ng/mL to 55.3 +/- 12.75 ng/mL, and (131)I uptake was evident in 3 of the 4 patients. No major adverse effects were reported after rhTSH administration. CONCLUSION: Our results show that the measurement of serum Tg concentrations after rhTSH has a higher diagnostic value than whole-body scanning in detecting the persistence of thyroid tissue. Therefore, rhTSH should be administered in TSH-suppressed patients with basal serum Tg concentrations of <2 ng/mL because the increment in serum Tg concentrations may reveal the persistence of thyroid tissue in these patients.

Adult↗

PubMed2001

[Efficacy and safety of low-dose heparin (30 IU/kg) during coronary angioplasty].

High doses of heparin are recommended during coronary angioplasty although platelet inhibition seems to play a role in the prevention of ischaemic complications. Low dose heparin could reduce the incidence of local complications without increasing that of major coronary events. The authors report the results of a prospective register of coronary angioplasties performed by the femoral approach with a single bolus of 30 IU/Kg of heparin and immediate withdrawal of the 6 French introducer. Only patients with recent infarction or left main stem disease were excluded. All underwent clinical examination and ultrasonic scanning of the puncture site the day after the procedure. Four hundred and eighteen patients were included (mean age: 63.3 +/- 11 years; 79% men; 77% stenting). The average dose of heparin was 2253 +/- 1056 IU; the average procedure time was 25 +/- 16 minutes, and a final activated clotting time was 174 +/- 69 ms. The duration of normal compression was 7.7 +/- 3 min. Eighty-three point five per cent of patients were discharged the day after the procedure with a global cardiovascular complication rate of 2.87%. At 1 month, 1.67% of secondary cardiovascular events was recorded. Ultrasonography of the puncture site was abnormal in 7.6% of patients. Only one serious vascular complication (0.24%) requiring transfusion and surgical repair, was observed. The authors conclude that the use of low dose heparin appears effective and safe in cases without acute myocardial infarction. This protocol allows faster mobilisation and earlier hospital discharge of patients.

Aged↗

PubMed2000

Different metabolizing ability of thiol reactants in human and rat blood: biochemical and pharmacological implications.

The effect of oxidants, electrophiles, and NO donors in rat or human erythrocytes was analyzed to investigate the influence of protein sulfhydryl groups on the metabolism of these thiol reactants. Oxidant-evoked alterations in thiolic homeostasis were significantly different in the two models; large amounts of glutathione protein mixed disulfides were produced in rat but not in human erythrocytes by treatment with hydroperoxides or diamide. The disappearance of all forms of glutathione (reduced, disulfide, protein mixed disulfide) was induced by menadione only in human erythrocytes. The treatment of rat red blood cells with electrophiles produced glutathione S-conjugates to a much lower extent than in human red blood cells; GSH was only minimally depleted in rat red blood cells. The NO donor S-nitrosocysteine induced a rapid transnitrosation reaction with hemoglobin in rat erythrocytes producing high levels of S-nitrosohemoglobin; this reaction in human red blood cells was negligible. All drugs were cleared more rapidly in rat than in human erythrocytes. Unlike human Hb, rat hemoglobin contains three families of protein SH groups; one of these located at position beta125 is directly implicated in the metabolism of thiol reactants. This is thought to influence significantly the biochemical, pharmacological, and toxicological effects of some drugs.

Adult↗

PubMed2000

The importance of erythroid expansion in determining the extent of apoptosis in erythroid precursors in patients with beta-thalassemia major.

Beta-thalassemia major is characterized by ineffective erythropoiesis leading to severe anemia and extensive erythroid expansion. The ineffective erythropoiesis is in part due to accelerated apoptosis of the thalassemic erythroid precursors; however, the extent of apoptosis is surprisingly variable. To understand this variability as well as the fact that some patients undergoing allogeneic marrow transplantation are resistant to the myeloablative program, we attempted more quantitative analyses. Two groups of patients totaling 44 were studied, along with 25 healthy controls, and 7 patients with hemolysis and/or ineffective erythropoeisis. By 2 flow cytometric methods, thalassemic erythroid precursors underwent apoptosis at a rate that was 3 to 4 times normal. Because thalassemic marrow has between 5- to 6-fold more erythroid precursors than healthy marrow, this translated into an absolute increase in erythroid precursor apoptosis of about 15-fold above our healthy controls. In searching for the causes of the variability in thalassemic erythroid precursor apoptosis, we discovered tight direct correlations between the relative and absolute extent of apoptosis and the extent of erythroid expansion as measured either by the absolute number of marrow erythroid precursors or by serum soluble transferrin receptor levels. These results could mean that the most extreme rates of erythroid proliferation lend themselves to cellular errors that turn on apoptotic programs. Alternatively, extreme rates of erythroid hyperplasia and apoptosis might be characteristic of more severely affected patients. Lastly, extreme erythroid hyperplasia could generate such numbers of apoptotic erythroid precursors that marrow macrophages are overwhelmed, leaving more apoptotic cells in the sample.

Adolescent↗

PubMed2000

Rodlet cells and other inflammatory cells of Phoxinus phoxinus infected with Raphidascaris acus (Nematoda).

Rodlet cells (RCs), and other inflammatory cells, namely eosinophile granule cells (EGCs), eosinophilic granulocytes and epithelioid cells in the liver, pancreas and peritoneal serosa of uninfected and naturally parasitized minnow Phoxinus phoxinus (Linnaeus, 1758), were studied by light and electron microscopy. Forty-eight minnows were examined and in 18 fishes encysted larvae of the nematode Raphidascaris acus (Bloch, 1779) were encountered, mainly in the pancreas. The number of larvae in the latter organ ranged from 2 to 46. Nematode larvae were encapsulated by epithelioid granulomata, and these cells displayed typical epithelial characteristics such as desmosomes and tonofilaments. EGCs and RCs characteristically surrounded the reactive foci and were suggestive of an integrated inflammatory network involving both cell types. In many instances RCs were noticed at the periphery of the pancreas, beneath the peritoneal serosa, partially or entirely surrounded by mesothelial cells. In the latter situation partially damaged RCs were present in the splancnic cavity entirely surrounded but not truly phagocytized (no phagolysosome occurred) by mesothelial cells, which shared the same ultrastructural features of epithelioid cells. This phenomenon has never been described and may represent a peculiar turnover of RCs in the pancreas likely related to the high sensitivity to damage. A significant difference (p < 0.01) in the number of RCs between uninfected and parasitized fish was noticed in the liver and pancreas. The data suggest that RCs represent an inflammatory cell type closely linked to other piscine inflammatory cells, such as EGCs, epithelioid cells and mesothelial cells.

Animals↗

PubMed2000

Group B Streptococcus induces apoptosis in macrophages.

Group B Streptococcus (GBS) is a pathogen that has developed some strategies to resist host immune defenses. Because phagocytic killing is an important pathogenetic mechanism for bacteria, we investigated whether GBS induces apoptosis in murine macrophages. GBS type III strain COH31 r/s (GBS-III) first causes a defect in cell membrane permeability, then at 24 h, apoptosis. Apoptosis was confirmed by several techniques based on morphological changes and DNA fragmentation. Cytochalasin D does not affect apoptosis, suggesting that GBS-III needs not be within the macrophage cytoplasm to promote apoptosis. Inhibition of host protein synthesis prevents apoptosis, whereas inhibition of caspase-1 or -3, does not. Therefore, GBS can trigger an apoptotic pathway independent of caspase-1 and -3, but dependent on protein synthesis. Inhibition of apoptosis by EGTA and PMA, and enhancement of apoptosis by calphostin C and GF109203X suggests that an increase in the cytosolic calcium level and protein kinase C activity status are important in GBS-induced apoptosis. Neither alteration of plasma membrane permeability nor apoptosis were induced by GBS grown in conditions impeding hemolysin expression or when we used dipalmitoylphosphatidylcholine, which inhibited GBS beta-hemolytic activity, suggesting that GBS beta-hemolysin could be involved in apoptosis. beta-Hemolysin, by causing membrane permeability defects, could allow calcium influx, which initiates macrophage apoptosis. GBS also induces apoptosis in human monocytes but not in tumor lines demonstrating the specificity of its activity. This study suggests that induction of macrophage apoptosis by GBS is a novel strategy to overcome host immune defenses.

1,2-Dipalmitoylphosphatidylcholine↗