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1.
Plant Mol Biol ; 90(6): 561-74, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26821805

ABSTRACT

A wide range of rhizosphere diazotrophic bacteria are able to establish beneficial associations with plants, being able to associate to root surfaces or even endophytically colonize plant tissues. In common, both associative and endophytic types of colonization can result in beneficial outcomes to the plant leading to plant growth promotion, as well as increase in tolerance against biotic and abiotic stresses. An intriguing question in such associations is how plant cell surface perceives signals from other living organisms, thus sorting pathogens from beneficial ones, to transduce this information and activate proper responses that will finally culminate in plant adaptations to optimize their growth rates. This review focuses on the recent advances in the understanding of genetic and epigenetic controls of plant-bacteria signaling and recognition during beneficial associations with associative and endophytic diazotrophic bacteria. Finally, we propose that "soil-rhizosphere-rhizoplane-endophytes-plant" could be considered as a single coordinated unit with dynamic components that integrate the plant with the environment to generate adaptive responses in plants to improve growth. The homeostasis of the whole system should recruit different levels of regulation, and recognition between the parties in a given environment might be one of the crucial factors coordinating these adaptive plant responses.


Subject(s)
Bacterial Physiological Phenomena/genetics , Endophytes/physiology , Epigenesis, Genetic , Nitrogen Fixation/physiology , Plants/microbiology , Epigenesis, Genetic/physiology , Nitrogen Fixation/genetics , Plants/genetics , Rhizosphere
2.
J Exp Bot ; 65(19): 5631-42, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25114015

ABSTRACT

Some beneficial plant-interacting bacteria can biologically fix N2 to plant-available ammonium. Biological nitrogen fixation (BNF) is an important source of nitrogen (N) input in agriculture and represents a promising substitute for chemical N fertilizers. Diazotrophic bacteria have the ability to develop different types of root associations with different plant species. Among the highest rates of BNF are those measured in legumes nodulated by endosymbionts, an already very well documented model of plant-diazotrophic bacterial association. However, it has also been shown that economically important crops, especially monocots, can obtain a substantial part of their N needs from BNF by interacting with associative and endophytic diazotrophic bacteria, that either live near the root surface or endophytically colonize intercellular spaces and vascular tissues of host plants. One of the best reported outcomes of this association is the promotion of plant growth by direct and indirect mechanisms. Besides fixing N, these bacteria can also produce plant growth hormones, and some species are reported to improve nutrient uptake and increase plant tolerance against biotic and abiotic stresses. Thus, this particular type of plant-bacteria association consists of a natural beneficial system to be explored; however, the regulatory mechanisms involved are still not clear. Plant N status might act as a key signal, regulating and integrating various metabolic processes that occur during association with diazotrophic bacteria. This review will focus on the recent progress in understanding plant association with associative and endophytic diazotrophic bacteria, particularly on the knowledge of the N networks involved in BNF and in the promotion of plant growth.


Subject(s)
Bacteria/metabolism , Nitrogen Fixation , Nitrogen/metabolism , Plants/microbiology , Crops, Agricultural , Endophytes , Models, Biological , Plant Root Nodulation , Plant Roots/microbiology , Signal Transduction , Symbiosis
3.
Vet Immunol Immunopathol ; 132(2-4): 153-9, 2009 Dec 15.
Article in English | MEDLINE | ID: mdl-19559488

ABSTRACT

The Duffy antigen is the only receptor for Plasmodium vivax, a hemoparasite of the phylum Apicomplexa and the cause of vivax malaria in humans. Resistance to this parasite in the majority of black African individuals and their descendents is due to a mutation in the gene promoter region, which blocks its transcription on erythrocytes. Regarding bovine babesiosis, it is known that taurine breeds are more susceptible to parasite infection than zebuine breeds. In order to verify whether the same human resistance occurs in bovine, the 5' flanking region of the DARC gene was isolated and characterized in Bos indicus and Bos taurus. Four single nucleotide polymorphisms were identified and genotyped (SNP1: EF_647729.1:g.91C>T; SNP2: EF_647729.1:g.405C>T; SNP3: EF_647729.1: g.433A>G and SNP4: EF_647729.1:g.588A>G), which showed significant frequency differences among 99 bovines of each species (n=198). Characterization of the isolated region revealed the presence of 6 putative haplotypes, 14 genotypes, which are formed by haplotypes, and numerous putative transcription factor binding sites. Only the thymine presence on SNPs 1 and 2, more common in B. indicus, was observed to alter some of the sites in this region. Despite this fact, analyses through real-time PCR on bovines that present the most common homozygote genotypes of each species, which contrast for all the polymorphism, revealed no difference on the DARC gene transcription. Thus, in principle, it was concluded that the polymorphisms identified would not be useful as molecular markers in an improvement program for resistance to babesiosis.


Subject(s)
Cattle/genetics , Cattle/immunology , Duffy Blood-Group System/genetics , Receptors, Chemokine/genetics , 5' Flanking Region , Alleles , Animals , Babesia/immunology , Babesia/pathogenicity , Babesiosis/genetics , Babesiosis/immunology , Babesiosis/veterinary , Base Sequence , Cattle/blood , Cattle Diseases/genetics , Cattle Diseases/immunology , DNA Primers/genetics , Gene Frequency , Haplotypes , Humans , Molecular Sequence Data , Plasmodium vivax/immunology , Plasmodium vivax/pathogenicity , Polymorphism, Single Nucleotide , Promoter Regions, Genetic , Species Specificity , Transcription, Genetic
4.
Biochimie ; 89(11): 1425-32, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17614193

ABSTRACT

We show that MDCK I cells express, besides the classical (Na(+)+K(+))ATPase, a Na(+)-stimulated ATPase activity with the following characteristics: (1) K(0.5) for Na(+) 7.5+/-1.5 mM and V(max) 23.12+/-1.1 nmol Pi/mg per min; (2) insensitive to 1 mM ouabain and 30 mM KCl; and (3) inhibited by furosemide and vanadate (IC(50) 42.1+/-8.0 and 4.3+/-0.3 microM, respectively). This enzyme forms a Na(+)-stimulated, furosemide- and hydroxylamine-sensitive ATP-driven acylphosphate phosphorylated intermediate with molecular weight of 100 kDa. Immunoprecipitation of the (Na(+)+K(+))ATPase with monoclonal anti-alpha(1) antibody reduced its activity in the supernatant by 90%; the Na(+)-ATPase activity was completely maintained. In addition, the formation of the Na(+)-stimulated, furosemide- and hydroxylamine-sensitive ATP-driven acylphosphate intermediate occurred at the same magnitude as that observed before immunoprecipitation. These data suggest that Na(+)-ATPase and (Na(+)+K(+))ATPase activities are independent, with Na(+)-ATPase belonging to a different enzyme entity.


Subject(s)
Adenosine Triphosphatases/isolation & purification , Adenosine Triphosphatases/metabolism , Ouabain/pharmacology , Sodium-Potassium-Exchanging ATPase/isolation & purification , Sodium-Potassium-Exchanging ATPase/metabolism , Adenosine Triphosphatases/antagonists & inhibitors , Adenosine Triphosphate/metabolism , Animals , Cell Line , Dogs , Enzyme Inhibitors/pharmacology , Furosemide/pharmacology , Hydrolysis/drug effects , Hydroxylamine/pharmacology , Immunoblotting , Immunoprecipitation , Kinetics , Phosphorylation/drug effects , Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors , Vanadates/pharmacology
5.
Regul Pept ; 127(1-3): 177-82, 2005 Apr 15.
Article in English | MEDLINE | ID: mdl-15680484

ABSTRACT

In previous papers we showed that Ang II increases the proximal tubule Na+-ATPase activity through AT1/PKC pathway [L.B. Rangel, C. Caruso-Neves, L.S. Lara, A.G. Lopes, Angiotensin II stimulates renal proximal tubule Na+-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316, L.B.A. Rangel, A.G. Lopes, L.S. Lara, C. Caruso-Neves, Angiotensin II stimulates renal proximal tubule Na+)-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316]. In the present paper, we study the involvement of PI-PLCbeta on the stimulatory effect of angiotensin II (Ang II) on the proximal tubule Na+-ATPase activity. Western blotting assays, using a polyclonal antibody for PI-PLCbeta, show a single band of about 150 KDa, which correspond to PI-PLCbeta isoforms. Ang II induces a rapid decrease in PIP2 levels, a PI-PLCbeta substrate, being the maximal effect observed after 30 s incubation. This effect of Ang II is completely abolished by 5 x 10(-8) M U73122, a specific inhibitor of PI-PLCbeta. In this way, the effect of 10(-8) M Ang II on the proximal tubule basolateral membrane (BLM) Na+-ATPase activity is completely abolished by 5 x 10(-8) M U73122. The increase in diacylglycerol (DAG) concentration, an product of PI-PLCbeta, from 0.1 to 10 nM raises the Na+-ATPase activity from 6.1+/-0.2 to 13.1+/-1.8 nmol Pi mg(-1) min(-1). This effect is similar and non-additive to that observed with Ang II. Furthermore, the stimulatory effect of 10 nM DAG is completely reversed by 10(-8) M calphostin C (Calph C), an inhibitor of PKC. Taken together these data indicate that Ang II stimulates the Na+-ATPase activity of proximal tubule BLM through a PI-PLCbeta/PKC pathway.


Subject(s)
Adenosine Triphosphatases/metabolism , Angiotensin II/metabolism , Cation Transport Proteins/metabolism , Isoenzymes/metabolism , Kidney Tubules, Proximal/enzymology , Phosphatidylinositol Diacylglycerol-Lyase/metabolism , Animals , Diglycerides/metabolism , Estrenes/metabolism , Isoenzymes/antagonists & inhibitors , Phosphatidylinositol 4,5-Diphosphate/metabolism , Phosphatidylinositol Diacylglycerol-Lyase/antagonists & inhibitors , Pyrrolidinones/metabolism , Swine
6.
Pesqui Odontol Bras ; 15(3): 257-62, 2001.
Article in Portuguese | MEDLINE | ID: mdl-11705274

ABSTRACT

The purposes of the present study were: 1) to investigate the biocompatibility of a natural resin (made of fatty acids extracted from Ricinus communis) implanted in the dental alveolus of rats and 2) to verify any possible interference of that material in the osseous healing following tooth extraction. The resin (AUG-EX, Poliquil Araraquara Polímeros Químicos LTDA, Araraquara--SP) was placed inside de alveoli immediately after extraction of the upper right incisors. The animals were sacrificed 1, 2, 3 and 6 weeks after extraction or extraction + implantation. The hemi-maxillae were decalcified and processed for paraffin embedding. Longitudinal 6-micrometer-thick semi-serial sections stained with hematoxylin and eosin were obtained. Histologic examination showed particles of irregular shape and variable size (700-1200 microns) localized in the medium/cervical alveolar thirds, with a scanty but persistent foreign body reaction. From the second week on, as the relative volume of bone trabeculae increased, it was seen in close contact with the surface of the implanted material in some regions. Histometric analysis (differential point counting method), used to quantify the healing process in the apical third, showed a small but significant decrease (13%-20%) in new bone formation in the implanted rats. In conclusion, the results show that, in spite of its biocompatible nature, the studied resin hinders the post-extration healing process.


Subject(s)
Biocompatible Materials , Ricin , Tooth Socket , Animals , Male , Rats , Rats, Wistar , Tooth Socket/pathology
7.
J Exp Med ; 194(8): 1141-50, 2001 Oct 15.
Article in English | MEDLINE | ID: mdl-11602642

ABSTRACT

Interleukin 7 is a crucial factor for the development of murine T and B lymphocytes. We now report that, in the absence of interleukin 7, B lymphocyte production takes place exclusively during fetal and perinatal life, ceasing after 7 wk of age. In peripheral organs, however, the pool of B lymphocytes is stable throughout adult life and consists only of cells that belong to the B1 and marginal zone (MZ) compartments. This is accompanied by a 50-fold increase in the frequency of immunoglobulin (Ig)M- and IgG-secreting cells, and the concentration of serum immunoglobulins is increased three- to fivefold. Both the MZ phenotype and the increase in serum IgM are T cell independent. These findings reveal a previously undescribed pathway of B lymphopoiesis that is active in early life and is interleukin 7 independent. This pathway generates B1 cells and a normal sized MZ B lymphocyte compartment.


Subject(s)
B-Lymphocytes/cytology , Interleukin-7/immunology , Lymphocyte Activation/immunology , Aging/blood , Animals , B-Lymphocytes/immunology , Biomarkers , Bone Marrow Cells/cytology , Cell Differentiation , Female , Hematopoiesis , Immunoglobulin A/blood , Immunoglobulin G/blood , Immunoglobulin M/blood , Immunophenotyping , Interleukin-7/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Nude , Plasma Cells/cytology , Plasma Cells/immunology , Spleen/cytology
8.
Histol Histopathol ; 16(2): 481-5, 2001 04.
Article in English | MEDLINE | ID: mdl-11332704

ABSTRACT

The purpose of the present study was to investigate the effect of prolonged immobilization-induced stress on reparative bone formation, using the rat alveolar healing as an experimental protocol. Stress was attained by immobilization for 2 hours a day, beginning three days before extraction of the upper right incisors and continuing until sacrifice. The stress condition was assayed on the basis of plasma corticosterone concentration (measured by double-antibody radioimmunoassay), which increased by 2.5 to 4 times in rats submitted to immobilization. The volume density of neoformed bone filling the alveolar socket was quantified by a histometric differential point-counting method 7 to 21 days following tooth extraction. Stress caused a significant delay in reparative bone increment, somewhat related to impairment of coagulum remission and/or organization.


Subject(s)
Bone Regeneration , Immobilization/adverse effects , Stress, Physiological , Tooth Socket/physiology , Animals , Corticosterone/analysis , Corticosterone/blood , Male , Matched-Pair Analysis , Radioimmunoassay , Rats , Rats, Wistar , Time Factors , Wound Healing
9.
Arch Oral Biol ; 46(4): 375-9, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11269871

ABSTRACT

The purpose was to investigate whether amlodipine, a second-generation calcium antagonist used for the treatment of hypertension and angina, interferes with healing of rat alveolar bone. A progressive increase in volume density of new bone filling the socket was quantified by a histometric differential point-counting method 7-42 days after tooth extraction. The results showed a 20-30% decrease in bone volume fraction in the alveolus of amlodipine-treated animals from 7 days on, in addition to a higher (7-35%) volume fraction of connective tissue and a tendency toward an increase in the volume fraction of persisting coagulum. If confirmed in humans, the knowledge of a deleterious effect of Ca-channel blockers in hindering alveolar bone healing would be important in planning oral operations involving bone tissue, including those for device implantation.


Subject(s)
Amlodipine/pharmacology , Bone Regeneration/drug effects , Calcium Channel Blockers/pharmacology , Tooth Socket/drug effects , Animals , Male , Rats , Rats, Wistar , Tooth Extraction , Tooth Socket/physiology , Wound Healing/drug effects
10.
Exp Toxicol Pathol ; 52(4): 353-6, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10987190

ABSTRACT

The purpose of the present study was to investigate whether treatment of male rats with the calcium antagonist amlodipine, used in the treatment of hypertension and angina, interferes with the reproductive function of male rats. Amlodipine treatment (0.04 mg amlodipine besylate/rat/day for 30 days) decreased plasma follicle-stimulating hormone and testosterone but not luteinizing hormone or prolactin concentrations (measured by double-antibody radioimmuno-assay). A significant reduction (23%) was observed in sperm density (sperm suspension collected from the cauda epididymidis) as well as in the amount of mature spermatids (14%) and Sertoli cells (9%) counted in seminiferous tubule cross-sections (400 x magnification). The results reveal the deleterious effects of subacute amlodipine treatment on the reproductive function of male rats.


Subject(s)
Amlodipine/adverse effects , Calcium Channel Blockers/adverse effects , Sperm Count , Testis/drug effects , Animals , Follicle Stimulating Hormone/blood , Infertility, Male/chemically induced , Luteinizing Hormone/blood , Male , Rats , Rats, Wistar , Testis/pathology , Testosterone/blood
11.
Braz J Med Biol Res ; 33(9): 1105-9, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10973146

ABSTRACT

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa.


Subject(s)
Fertility , Immobilization , Sexual Behavior, Animal , Sexual Maturation , Stress, Physiological/physiopathology , Animals , Case-Control Studies , Corpus Luteum/physiology , Female , Latency Period, Psychological , Male , Pregnancy , Rats , Rats, Wistar
12.
Braz. j. med. biol. res ; 33(9): 1105-9, Sept. 2000.
Article in English | LILACS | ID: lil-267972

ABSTRACT

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa


Subject(s)
Animals , Male , Rats , Female , Fertility , Immobilization , Sexual Behavior , Sexual Maturation , Stress, Physiological , Case-Control Studies , Corpus Luteum/physiology , Latency Period, Psychological , Rats, Wistar
13.
Andrologia ; 32(1): 7-11, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10702860

ABSTRACT

We investigated whether chronic stress, applied from prepuberty to early puberty, interferes with the spermatogenic and androgenic testicular functions. Male pubertal rats (40 days old) were immobilized 6 h per day for 15 days. Plasma concentrations of corticosterone, prolactin and testosterone were significantly augmented following immobilization, whereas plasma luteinizing hormone decreased and follicle-stimulating hormone was not altered. Acute immobilization (5 min) increased prolactin and testosterone levels in control rats but caused a significantly higher increase in these hormones when superimposed on chronic stress. A lower extent of testicular maturation was observed in pubertal rats immobilized from prepuberty.


Subject(s)
Immobilization/physiology , Stress, Physiological/blood , Stress, Physiological/pathology , Testis/growth & development , Testosterone/blood , Animals , Corticosterone/blood , Follicle Stimulating Hormone/blood , Luteinizing Hormone/blood , Male , Prolactin/blood , Rats , Rats, Wistar , Sexual Maturation/physiology , Spermatogenesis/physiology
14.
Anat Histol Embryol ; 28(4): 217-20, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10488624

ABSTRACT

A histological study was conducted on the testes of adult domestic quails (Coturnix coturnix japonica) over a year. The results revealed a clear variation of testicular weight, seminiferous tubule diameter, and the thickness and composition of the germinal epithelium over the year. The highest testicular weights were detected at the end of the autumn and during the winter (short-day period), reaching a maximum, together with spermatogenic activity, in September (long-day period in the southern hemisphere). In contrast, both testicular weight and spermatogenic activity were markedly decreased at the end of spring and during summer (long-day periods in the southern hemisphere).


Subject(s)
Coturnix/anatomy & histology , Seasons , Testis/anatomy & histology , Animals , Coturnix/physiology , Epithelial Cells/cytology , Male , Organ Size , Seminiferous Tubules/anatomy & histology , Testis/cytology , Testis/physiology
15.
Braz. j. med. biol. res ; 31(11): 1443-8, Nov. 1998. tab, graf
Article in English | LILACS | ID: lil-224480

ABSTRACT

We investigated whether chronic stress applied from prepuberty to full sexual maturity interferes with spermatogenic and androgenic testicular functions. Male Wistar rats (40 days old) were immobilized 6 h a day for 60 days. Following immobilization, plasma concentrations of corticosterone and prolactin increased 135 per cent and 48 per cent, respectively, while plasma luteinizing hormone and testosterone presented a significant decrease of 29 per cent and 37 per cent, respectively. Plasma concentration of follicle-stimulating hormone was not altered in stressed rats. Chronic stress reduced the amount of mature spermatids in the testis by 16 per cent and the spermatozoon concentration in the cauda epididymidis by 32 per cent. A 17 per cent reduction in weight and a 42 per cent decrease in DNA content were observed in the seminal vesicle of immobilized rats but not in its fructose content. The growth and secretory activity of the ventral prostate were not altered by chronic stress.


Subject(s)
Animals , Male , Rats , Hormones/blood , Immobilization , Sexual Maturation , Spermatogenesis , Stress, Physiological , Testis/physiology , Androgens/blood , Prostate , Rats, Wistar , Seminal Vesicles
16.
Exp Physiol ; 83(5): 701-4, 1998 Sep.
Article in English | MEDLINE | ID: mdl-9793790

ABSTRACT

A stress protocol--6 h of daily immobilization--was applied throughout male rat sexual development. Immobilization caused a small reduction in food intake and body weight gain whereas pair-fed animals had a marginal decrease only in body weight gain. Stress, confirmed by increased plasma adrenocorticotrophic hormone (ACTH) and corticosterone, caused a decrease in plasma luteinizing hormone (LH) after 15 and 60 days of immobilization and in plasma testosterone after 60 days, but produced an opposite androgenic response in pubertal animals (15 days of immobilization). A persumed sympathetic over-stimulation is suggested to account for increased testosterone levels in pubertal stressed rats.


Subject(s)
Sex , Stress, Physiological/physiopathology , Adrenocorticotropic Hormone/blood , Animals , Corticosterone/blood , Growth , Immobilization , Luteinizing Hormone/blood , Male , Rats , Rats, Wistar , Stress, Physiological/blood , Stress, Physiological/etiology , Testosterone/blood
17.
Histol Histopathol ; 13(2): 385-9, 1998 04.
Article in English | MEDLINE | ID: mdl-9589896

ABSTRACT

Previous studies from our laboratory have shown that low-intensity ultrasound applied to the scrotum of prepubertal rats causes a 62% increase in plasma testosterone, suggesting a possible stimulation of LH receptors and/or the enzymes controlling the steroidogenic process. The purpose of the present study was to investigate whether low-intensity ultrasound has a stimulatory effect on the androgenic activity of aged testes. In addition to plasma testosterone, LH and FSH, the testicular spermatogenic status was also analysed. Ultrasound applied to the scrotum of aged rats did not stimulate sperm production, which was significantly reduced compared to sexually mature animals, and failed to re-establish the steroidogenic testicular function, which was decreased by 74%, suggesting an inherent loss of gonadal steroidogenic competence.


Subject(s)
Aging/metabolism , Testis/diagnostic imaging , Testis/metabolism , Animals , Follicle Stimulating Hormone/metabolism , Luteinizing Hormone/metabolism , Male , Rats , Rats, Wistar , Testis/pathology , Testis/physiology , Testosterone/metabolism , Ultrasonography
18.
Braz J Med Biol Res ; 31(11): 1443-8, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9921282

ABSTRACT

We investigated whether chronic stress applied from prepuberty to full sexual maturity interferes with spermatogenic and androgenic testicular functions. Male Wistar rats (40 days old) were immobilized 6 h a day for 60 days. Following immobilization, plasma concentrations of corticosterone and prolactin increased 135% and 48%, respectively, while plasma luteinizing hormone and testosterone presented a significant decrease of 29% and 37%, respectively. Plasma concentration of follicle-stimulating hormone was not altered in stressed rats. Chronic stress reduced the amount of mature spermatids in the testis by 16% and the spermatozoon concentration in the cauda epididymidis by 32%. A 17% reduction in weight and a 42% decrease in DNA content were observed in the seminal vesicle of immobilized rats but not in its fructose content. The growth and secretory activity of the ventral prostate were not altered by chronic stress.


Subject(s)
Hormones/blood , Immobilization , Sexual Maturation , Spermatogenesis/physiology , Stress, Physiological , Testis/physiology , Androgens/blood , Animals , Male , Prostate , Rats , Rats, Wistar , Seminal Vesicles
19.
Anat Histol Embryol ; 26(4): 337-9, 1997 Dec.
Article in English | MEDLINE | ID: mdl-9400052

ABSTRACT

A morphometric study was conducted on the testis of the domestic quail Coturnix coturnix japonica to determine testicular kinetics. We investigated the variability along the year of testicular parameters such as seminiferous tubule diameter, germinal epithelium height and amount of meiotic figures of maturing spermatids in the seminiferous epithelium and of sperm in the tubular lumen. The results of morphometric analysis showed the occurrence of an annual testicular cycle defined by four distinct phases: a resting phase (at the end of summer), a recrudescence phase (in the fall), a proliferative phase (at the end of winter and beginning of spring), and a regression phase (spring and summer). We also observed that the testes of adult quails present elevated and maximal spermatogenic activity in fall-winter (short-day period) and at the beginning of spring, respectively, and lower values in spring and summer (long-day periods), with minimum values at the end of summer.


Subject(s)
Coturnix/physiology , Testis/physiology , Animals , Cell Division/physiology , Circadian Rhythm/physiology , Coturnix/anatomy & histology , Male , Meiosis/physiology , Seasons , Spermatozoa/cytology , Testis/anatomy & histology , Testis/cytology
20.
Int J Oral Maxillofac Surg ; 26(2): 149-52, 1997 Apr.
Article in English | MEDLINE | ID: mdl-9151174

ABSTRACT

The biocompatibility of polyurethane resin-implants derived from castor bean (Ricinus communis) was analyzed in the rat dental alveolus. Histometric evaluation of trial areas adjacent to the implants showed, by week 1, the polymer granules encircled by a conspicuous capsule and surrounded by immature connective tissue. By weeks 2 and 3, the implants were surrounded by less prominent fibrous capsules and most of the tested area was occupied by mature trabecular bone. By week 6, the fibrous capsule was thinner and the tested area was almost totally covered with bone, which in several places was in close contact with the implants. The results suggest that the material is compatible, as it was progressively integrated into alveolar bone in the wound-healing process.


Subject(s)
Alveolar Process/physiology , Biocompatible Materials , Osseointegration , Polyurethanes , Prostheses and Implants , Wound Healing/physiology , Animals , Ricinus communis , Male , Plants, Toxic , Rats , Rats, Wistar
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