23 research outputs found
Reakcja błony śluzowej jamy ustnej na kontakt z tytanem klasy IV
Although titanium dental implants are characterized by great biocompatibility, both
electrochemical and galvanic corrosion may take place in the oral environment, even in
the cases of full osseointegration of implants. The aim of the study was to evaluate processes
occurring in the gingival mucous membrane collected from dental implants after
a period of healing. In the gingival tissues in contact with implants fully integrated with
the bone, infiltrations composed of subpopulations of T lymphocytes (CD45R0 and CD25)
and Langerhans cells (S-100 positive) were found. The presence of immunologically competent
cells in the infiltrations indicated that the titanium implant was recognized by the
host’s immune system. The lack of clinical symptoms of hypersensitivity may suggest local
tolerance to a correctly healed intraosseous dental implant
Endothelin-l enhances thymocyte proliferation in monolaterally adrenalectomized rats with contralateral adrenocortical regeneration
Endothelins (ETs) are a family of vasoactive peptides widely distributed in the body systems, where they exert pleiotropic biological effects, acting through two main subtypes of receptors, named ETA and ETB. Evidence indicates that ET-1 plays a permissive role in the development of neural crest-derived structures, among which are the epithelia1 cells of the thymus. These cells are known to control proliferation and differentiation of thymocytes, a process requiring adequate levels of glucocorticoids. Therefore, we have investigated the effects of ET-1, that binds both ETA and ETB receptors, on thymocyte proliferation in monolaterally adrenalectomized rats with contralateral enucleated adrenal at day 4 and 8 of regeneration, when glucocorticoid production is very low and, respectively, rather normal. Metaphase index (percentage of metaphase arrested cells) of thymocytes is the lowest at day 4 of regeneration, and markedly rose at day 8, thereby confirming the need of sizable levels of circulating glucocorticoid for the maintenance of a normal rate of thymocyte proliferation. ET-l markedly increased the mitotic index of thymocytes at both times of adrenal regeneration. At day 8 of regeneration, the ETA-receptor antagonist BQ-123 markedly lowered mitotic index of thymocytes, and annulled its ET-1- evoked raise. Conversely, the ETB-receptor antagonist BQ-788 was ineffective. Collectively, these findings clearly indicate that endogenous ETs, through the activation of ETA receptors, are involved in the maintenance and stimulation of thymocyte proliferation in the adult rat, thereby playing a possibly important role in the modulation of the immune-system functions
Studies on the involvement of endogenous neuropeptides in the control of thymocyte proliferation in the rat
The possible involvement of endogenous vasoactive intestinal peptide (VIP), cholecystokinin (CCK) and neurotensin (NT) in the control of thymocyte proliferation has been investigated in vivo in the immature rat. For this task, we have studied the effects of the administration of selective antagonists of the receptors of the three neuropeptides on the mitotic index (%o of metaphase-arrested cells after vincristin injection) of thymocytes. Both CCK- and TN-receptor antagonists were ineffective. In contrast, two VIP receptor antagonists (VIP-As) enhanced the mitotic index of thymocytes. VIP reversed the effect of VIP-As, but when administered alone it did not alter the mitotic activity of thymocytes. In light of these findings, we conclude that endogenous VIP exerts a maximal tonic inhibitory influence on the basa1 proliferative activity of rat thymocytes, while endogenous CCK and NT do not play a relevant modulatory role in this process
Cholecystokinin, acting through the A receptor subtype, stimulates the proliferative activity of adrenocortical cells and thymocytes in the rat
Cholecystokinin (CCK) is a multifunctional regulatory peptide, which acts through two main subtypes of receptors, named CCK-A and CCK-B. Evidence indicates that CCK modulates cell proliferation in various tissues in a paracrine manner, and proofs are available of the presence of CCK in both adrenal glands and thymus. Hence, we have investigated the possible mitogenic action of this peptide on these two tissues, by evaluating the %o of metaphase-arrested cells after vincristin injection (mitotic index). The systemic administration of CCK (three subcutaneous injections of 20 nmollkg, 28, 16 and 4 h before the sacrifice) increased the mitotic index in both the outer adrenal and thymus cortexes of immature (20-day-old) rats and the enucleated adrenal gland of adult (2-month-old) animals at day 5 and 8 of regeneration. The simultaneous administration of equimolar doses of a selective CCK-A receptor antagonist blocked the effect of CCK, while a CCK-B antagonist was ineffective. These findings indicate that CCK exerts a marked CCK-A-mediated proliferogenic effect on both adrenal cortex and thymus in the rat, the physiological relevance of which, however, remains to be demonstrated. In fact, the administration of the CCK-A antagonist alone was ineffective, thereby casting doubts on the role played by endogenous CCK in the maintenance and stimulation of adrenal and thymus growth
Endothelin-1, acting via the A receptor subtype, stimulates thymocyte proliferation in the rat
Endothelins (ETs) are a family of vasoactive peptides widely distributed in the body systems, where they carry out major autocrine/paracrine regulatory functions, acting through two main subtypes of receptors (ETA and ETB). Evidence suggests that ETs play a permissive role in the development of neural crest-derived craniofacial structures, among which the thymus. Therefore, we have investigated whether ETs regulate thymocyte proliferation in the adult rat ET-1 (which binds both ETA and ETB receptors) increased the mitotic index (% of metaphase-arrested cells) in the thymus cortex, while ET-3 (which preferentially binds ETB) and the selective ETB-receptor agonists BQ-3020 and IRL-1620 did not. The ETA-receptor antagonists BQ-123 and BQ-610, but not the ETB-receptor antagonist BQ-788, abolished the ET-1 effect. Moreover, BQ-123 and BQ-610, when administered alone, evoked a significant decrease in the mitotic index. Collectively, these findings clearly indicate that endogenous ETs, through the activation of ETA receptors, are involved in the maintenance and stimulation thymocyte proliferation in the adult rat, thereby playing a possible important role in the modulation of the immune-system functions
Endothelin-1 enhances thymocyte proliferation in monolaterally adrenalectomized rats with contralateral adrenocortical regeneration
Endothelins (ETs) are a family of vasoactive peptides widely distributed in the body systems, where they exert pleiotropic biological effects, acting through two main subtypes of receptors, named ETA and ETB. Evidence indicates that ET-1 plays a permissive role in the development of neural crest-derived structures, among which are the epithelial cells of the thymus. These cells are known to control proliferation and differentiation of thymocytes, a process requiring adequate levels of glucocorticoids. Therefore, we have investigated the effects of ET-1, that binds both ETA and ETB receptors, on thymocyte proliferation in monolaterally adrenalectomized rats with contralateral enucleated adrenal at day 4 and 8 of regeneration, when glucocorticoid production is very low and, respectively, rather normal. Metaphase index (percentage of metaphase arrested cells) of thymocytes is the lowest at day 4 of regeneration, and markedly rose at day 8, thereby confirming the need of sizable levels of circulating glucocorticoid for the maintenance of a normal rate of thymocyte proliferation. ET-1 markedly increased the mitotic index of thymocytes at both times of adrenal regeneration. At day 8 of regeneration, the ETA-receptor antagonist BQ-123 markedly lowered mitotic index of thymocytes, and annulled its ET-1-evoked raise. Conversely, the ETB-receptor antagonist BQ-788 was ineffective. Collectively, these findings clearly indicate that endogenous ETs, through the activation of ETA receptors, are involved in the maintenance and stimulation of thymocyte proliferation in the adult rat, thereby playing a possibly important role in the modulation of the immune-system function
Endothelin-l enhances thymocyte proliferation in monolaterally adrenalectomized rats with contralateral adrenocortical regeneration
Endothelins (ETs) are a family of vasoactive
peptides widely distributed in the body systems, where
they exert pleiotropic biological effects, acting through
two main subtypes of receptors, named ETA and ETB.
Evidence indicates that ET-1 plays a permissive role in
the development of neural crest-derived structures,
among which are the epithelia1 cells of the thymus.
These cells are known to control proliferation and
differentiation of thymocytes, a process requiring
adequate levels of glucocorticoids. Therefore, we have
investigated the effects of ET-1, that binds both ETA and
ETB receptors, on thymocyte proliferation in monolaterally
adrenalectomized rats with contralateral
enucleated adrenal at day 4 and 8 of regeneration, when
glucocorticoid production is very low and, respectively,
rather normal. Metaphase index (percentage of
metaphase arrested cells) of thymocytes is the lowest at
day 4 of regeneration, and markedly rose at day 8,
thereby confirming the need of sizable levels of
circulating glucocorticoid for the maintenance of a
normal rate of thymocyte proliferation. ET-l markedly
increased the mitotic index of thymocytes at both times
of adrenal regeneration. At day 8 of regeneration, the
ETA-receptor antagonist BQ-123 markedly lowered
mitotic index of thymocytes, and annulled its ET-1-
evoked raise. Conversely, the ETB-receptor antagonist
BQ-788 was ineffective. Collectively, these findings clearly indicate that endogenous ETs, through the
activation of ETA receptors, are involved in the
maintenance and stimulation of thymocyte proliferation
in the adult rat, thereby playing a possibly important role
in the modulation of the immune-system functions
Studies on the involvement of endogenous neuropeptides in the control of thymocyte proliferation in the rat
The possible involvement of endogenous vasoactive intestinal peptide (VIP), cholecystokinin (CCK) and neurotensin (NT) in the control of thymocyte proliferation has been investigated in vivo in the immature rat. For this task, we have studied the effects of the administration of selective antagonists of the receptors of the three neuropeptides on the mitotic index (% of metaphase-arrested cells after vincristin injection) of thymocytes. Both CCK- and TN-receptor antagonists were ineffective. In contrast, two VIP receptor antagonists (VIP-As) enhanced the mitotic index of thymocytes. VIP reversed the effect of VIP-As, but when administered alone it did not alter the mitotic activity of thymocytes. In light of these findings, we conclude that endogenous VIP exerts a maximal tonic inhibitory influence on the basal proliferative activity of rat thymocytes, while endogenous CCK and NT do not play a relevant modulatory role in this process
Studies on the involvement Histology and Histopathology Cellular and Molecular Biology of endogenous neuropeptides in the control of thymocyte proliferation in the rat
The possible involvement of endogenous
vasoactive intestinal peptide (VIP), cholecystokinin
(CCK) and neurotensin (NT) in the control of thymocyte
proliferation ha s been investigated in vivo in the
immature rat. For this task, we have studied the effects
of the administration of selective antagonists of the
receptors of the three neuropeptides on the mitotic index
(%0 of metaphase-arrested cells after vincristin injection)
of thymocytes. Both CCK- and TN-receptor antagonists
were ineffective. In contrast, two VIP receptor
antago nists (VIP-As) enhanced the mitotic index of
thymocytes. VIP reversed the effect of VIP-As, but when
administered alone it did not alter the mitotic activity of
thymocytes. In light of these findings, we conclude that
endogenous VIP exerts a maximal tonic inhibitory
influence on the basal proliferative activity of rat
thymocytes, while endogenous CCK and NT do not play
a relevant modulatory role in thi process
Cholecystokinin, acting through the A receptor subtype, stimulates the proliferative activity of adrenocortical cells and thymocytes in the rat
Cholecystokinin (CCK) is a multifunctional regulatory peptide, which acts through two main subtypes of receptors, named CCK-A and CCK-B. Evidence indicates that CCK modulates cell proliferation in various tissues in a paracrine manner, and proofs are available of the presence of CCK in both adrenal glands and thymus. Hence, we have investigated the possible mitogenic action of this peptide on these two tissues, by evaluating the /1000 of metaphase-arrested cells after vincristin injection (mitotic index). The systemic administration of CCK (three subcutaneous injections of 20 nmol/kg, 28, 16 and 4 h before the sacrifice) increased the mitotic index in both the outer adrenal and thymus cortexes of immature (20-day-old) rats and the enucleated adrenal gland of adult (2-month-old) animals at day 5 and 8 of regeneration. The simultaneous administration of equimolar doses of a selective CCK-A receptor antagonist blocked the effect of CCK, while a CCK-B antagonist was ineffective. These findings indicate that CCK exerts a marked CCK-A-mediated proliferogenic effect on both adrenal cortex and thymus in the rat, the physiological relevance of which, however, remains to be demonstrated. In fact, the administration of the CCK-A antagonist alone was ineffective, thereby casting doubts on the role played by endogenous CCK in the maintenance and stimulation of adrenal and thymus growth