Biomedical subjects

E Rizzo

Publications and source records attributed to E Rizzo.

At least 19 recordsLinked to original sources

PubMed2006

Ovarian follicle growth in the catfish Iheringichthys labrosus (Siluriformes: Pimelodidae).

The morphofunctional organisation of the female reproductive system, the oocyte growth and the follicular envelope ultrastructure were studied by the first time in the catfish Iheringichthys labrosus from Upper Paraná River basin, Southeastern Brazil, in order to contribute to the knowledge of the reproductive behaviour strategies of this species. As in other Neotropical freshwater siluriforms, the ovaries are of the cystovarian type, the oocytes develop in an asynchronous pattern and mature oocytes are released in clusters in the ovarian lumen, being transported through the oviduct to the urogenital papilla. During the primary growth, nuclear material is transported to the ooplasm, forming the yolk nucleus, where proliferate membranous organelles. The onset of the zona radiata formation occurs during the late perionucleolar stage with the deposition of the outer layer. At the vitellogenic stage, this envelope reaches 6.35+/-0.84microm of thickness, being constituted by three distinct layers crossed by pore-canals containing oocyte and follicular cells processes. Cytochemical analyses evidence neutral glycoproteins in cortical alveoli, yolk globules and zona radiata. Follicular cells with squamous shape during the primary growth acquire synthetic activity at the secondary growth, reaching 37.82+/-4.72mum in height at the mature vitellogenic follicles. These cells accumulate sulphated polysaccharides in large electron-lucent vesicles during the vitellogenic stage which are possibly secreted to form a mucous coat at the egg surface. These evidences suggest that I. labrosus may have adhesive eggs as also detected in other Neotropical freshwater Siluriformes.

Animals↗

PubMed2005

[Non invasive multidetector CT angiography of coronary arteries: when and how should I do?].

Recent advances in multi-detector computed tomography technology offer a reliable tool for coronary arteries visualization and atherosclerotic plaque assessment. The objective of this article is to describe the principle of coronary angiography using multi-detector computed tomography, review the current diagnostic performances and help the reader to understand current applications and future challenges of multi-detector computed tomography in coronary artery disease diagnosis and management.

Coronary Angiography↗

PubMed2001

Continuous gametogenesis in the neotropical freshwater teleost, Bryconops affinis (Pisces:Characidae).

The gametogenesis of Bryconops affinis was studied by light, transmission and scanning electron microscopy. The spermatogenesis is semi-cystic and spermatids are released into the lumen of seminiferous tubules, where spermiogenesis is completed. Spermatozoa have an ovoid head, a rudimentary middle piece with a small number of mitochondria and long flagellum (primitive spermatozoa). The Sertoli and Leydig cells show secretory activity during spermatogenesis. By the end of this phenomenon, the Sertoli cells phagocytize the residual spermatozoa, while the Leydig cells show involuted characteristics. With regard to the oogenesis process, the oocyte development was divided into four stages based on the cytological characteristics of the oocyte and its surrounding layers. Ultrastructural analysis revealed that the zona pellucida is formed during the previtellogenic stage. Specializations associated to the outer layer of the zona pellucida may be related to the egg's adherence to the substrata.

Animals↗

PubMed2001

Morphofunctional organization of the male reproductive system of the catfish Iheringichthys labrosus (Lütken, 1874) (Siluriformes:Pimelodidae).

An anatomical, histological and ultrastructural study was made of the reproductive system and spermatogenesis of Iheringichthys labrosus. The testis are digitiform and consist of a sperm atogenic cranial region, a spermatogenic/secretory medial (transition) region, and a strictly secretory caudal region. The cranial region represents 66% of the total length of the maturing testis and its fringes or lobes have a length of 5.59 + 0.73 mm. The medial and caudal regions represent each 17% of the testicular length and their fringes have a length of 5.37 +/- 0.69 mm and 3.12 +/- 0.38 mm, respectively. Histologically, the cranial region of the testis is made up of seminiferous tubules with spermatogenic cells contained in cysts. These cells undergo synchronous development, inside the cysts where spermatogenesis is completed. The secretory caudal region does not constitute an individualized gland. Ultrastructurally, its secretory cells have a vesiculous nucleus and a cytoplasm with abundant dilated cisternae of rough endoplasmic reticulum. The caudal region produces a glycoproteic secretion and exhibits variable electron density during maturation. During the resting period, these cells are poor in synthesis organelles. The spermatozoa are of the primitive type, with a round head (1.56 +/- 0.11 microm), a rudimentary middle piece, and a long flagellum with a 9 + 2 axonemal arrangement.

Animals↗

PubMed2000

Postovulatory follicle: a model for experimental studies of programmed cell death or apoptosis in teleosts.

This is the first evidence of programmed cell death, or apoptosis, occurring in the postovulatory follicle (POF) of teleost fish. Females of Astyanax bimaculatus lacustris were submitted to induced ovulation through injecting pituitary extract. Ultrastructural analyses of POFs at time intervals varying from zero to four days postspawning showed several characteristic events of the apoptosis. Typical apoptotic figures, such as nucleus with chromatin condensation underlying the nuclear envelope in a crescent pattern and apoptotic bodies at different stages of formation and reabsorption, were observed in the follicular cells a few days after the onset of the postovulatory period. The results indicated that apoptosis is the major mechanism responsible for the elimination of the follicular cells in the POFs of A. bimaculatus lacustris during ovarian recovery postspawning. It is suggested that POFs might be used as an experimental model in dynamic studies involving cell death in teleosts.

Animals↗

PubMed1999

Dopamine affects parvalbumin expression during cortical development in vitro.

This study was undertaken to determine how dopamine influences cortical development. It focused on morphogenesis of GABAergic neurons that contained the calcium-binding protein parvalbumin (PV). Organotypic slices of frontoparietal cortex were taken from neonatal rats, cultured with or without dopamine, harvested daily (4-30 d), and immunostained for parvalbumin. Expression of parvalbumin occurred in the same regional and laminar sequence as in vivo. Expression in cingulate and entorhinal preceded that in lateral frontoparietal cortices. Laminar expression progressed from layer V to VI and finally II-IV. Somal labeling preceded fiber labeling by 2 d. Dopamine accelerated PV expression. In treated slices, a dense band of PV-immunoreactive neurons appeared in layer V at 7 d in vitro (DIV), and in all layers of frontoparietal cortex at 14 DIV, whereas in control slices such labeling did not appear until 14 and 21 DIV, respectively. The laminar distribution and dendritic branching of PV-immunoreactive neurons were quantified. More labeled neurons were in the superficial layers, and their dendritic arborizations were significantly increased by dopamine. Treatment with a D1 receptor agonist had little effect, whereas a D2 agonist mimicked dopamine's effects. Likewise, the D2 but not the D1 antagonist blocked dopamine-induced changes, indicating that they were mediated primarily by D2 receptors. Parvalbumin expression was accelerated by dopaminergic reinnervation of cortical slices that were cocultured with mesencephalic slices. Coapplication of the glutamate NMDA receptor antagonist MK801 or AP5 blocked dopamine-induced increases in dendritic branching, suggesting that changes were mediated partly by interaction with glutamate to alter cortical excitability.

Aging↗

PubMed1998

Histochemical and morphometric observations on the new tissue formed around mammary expanders coated with pyrolytic carbon.

The authors investigated tissue reaction around implanted silicone expanders, focusing on clinical morphological and morphometrical aspects. For use in breast reconstruction in post mastectomy patients, the surface of a medical-grade silicone elastomer was modified, without changing its bulk properties, by the addition of a pyrolytic carbon film. The presence of lipophagy, the number of foreign-body giant cells of histiocytic origin, and the number of MIB-1 positive nuclei (an index of proliferation for the reactive stromal population) were all seen to be influenced by the pyrolytic carbon coating. Indeed, all these parameters were lower in the membrane formed around Carbofilm TM-coated expanders, thus demonstrating the effective protective properties of pyrolytic carbon coating.

Adult↗

PubMed1998

Biomechanical behaviour at the distal third of the femur: possible use of a medial metaphyseal plate.

The incidence of fractures in the distal femur is becoming more frequent and they are often associated to complex lesions with potential complications. Operative treatment is mandatory for elderly people and several methods of internal fixation with appropriate implants have been developed, generally approaching the lateral aspect of the femur. An alternative antero-medial access was proposed several years ago but the biomechanical aspects of its application must be debated. The aim of the present study is to establish if adverse biomechanical effects should be expected when the plate is affixed at the medial side of the femur metaphysis, by analysing the strain pattern of a human cadaver femur submitted to loads simulated in different experimental conditions. Application of load resulted, as expected, in tension in the lateral aspect and compression in the medial aspect of the femur diaphysis but it turned more and more toward the anterior aspect and the compression turned toward the posterior aspect when the levels measured changed from proximal to distal. The plate was next to the neutral axis and produced a moderate stress protection effect (approx. 70 per cent). No biomechanical disadvantages have been observed as a result of the plate being apposed at the medial aspect instead of the conventional lateral aspect of the distal femur.

Aged↗

PubMed1998

In vivo cytogenetic studies of the genotoxic effects of polymethyl methacrylate employed in orthopaedics.

Polymethyl methacrylate (PMMA) is a material employed as a cement in prosthesis that has been found to induce cytogenetic damage in human lymphocytes in vitro. This effect is particularly achieved before the 5th day of the exposition, while after this period no significant variations appeared. In the present study, results of cytogenetic tests in humans are reported. Sister chromatid exchange analysis and micronucleus tests have been performed on lymphocytes of patients who had undergone prosthesization with cemented prosthesis (group A) or with biological anchorage prosthesis, as control (group B). DNA damage was investigated before implantation and 5 d after surgery in both groups. Cytogenetic tests did not show any significant increase in the number of micronuclei and sister chromatid exchanges with respect to control values in patients with PMMA cemented prosthesis.

Journal Article↗

PubMed1996

Quantitative scintigraphic evaluation of total knee arthroplasties: a feasibility study.

For the development and validation of a quantitative approach to the analysis of bone scans after total knee arthroplasty, 39 consecutive patients with 40 prostheses (6 males, 33 females; mean age, 70 years) were scheduled for clinical, radiographic, and scintigraphic examination ranging from 9 to 90 months after surgery. Twenty-seven total knee arthroplasties were considered to be asymptomatic and 13 symptomatic according to the clinical and radiographic findings. Significant differences were found for 99mTc-methylene diphosphonate uptake for femur and tibia and between symptomatic and asymptomatic patients. A reference range was determined for radionuclide uptake in the periprosthetic bone of the 27 asymptomatic total knee arthroplasties; this range was then used to identify loose total knee arthroplasties among the 13 symptomatic knees. With a clinical and radiographic followup performed 1 year after scintigraphy as a standard of comparison, a sensitivity of 88% (7/8) and a specificity of 100% (5/5) was demonstrated. These preliminary results suggest the feasibility of a quantitative approach to the scintigraphic evaluation of total knee arthroplasties after the first postsurgical year.

Aged↗

PubMed1991

The zona pellucida of the Brazilian white piranha, Serrasalmus brandtii Reinhardt 1874 (Pisces, Characidae): a cytological and cytochemical study.

The zona pellucida of vitellogenic oocytes of the Brazilian White Piranha (Serrasalmus brandtii) is composed of three layers traversed by radial striae which can be differentiated by cytological and cytochemical methods. Its formation begins in oocyte 2 (previtellogenesis), with the development of the outer layer. The middle layer is formed during vitellogenesis and the inner layer--which accounts for most of this envelope--in the fully vitellogenic oocyte. The chemical nature of each layer can be determined by cytochemical techniques for carbohydrates and proteins. The origin of the teleost zona pellucida is discussed.

Animals↗

PubMed1990

Plasmapheresis with exchange as primary treatment for thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is an uncommon disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia, fever and renal and neurologic dysfunction. As a result of the availability of plasmapheresis, we can report the results of 5 patients treated with plasmapheresis and exchange transfusion who also received intravenous corticosteroids as adjunctive therapy. Our 5 patients had a mean age of 41 years, and presented with a mean platelet count of 39 x 10(9)/L. Four of the 5 patients responded to treatment and were discharged in excellent condition. The 5th patient succumbed to her disease. We concluded that plasmapheresis with exchange transfusion is a rapid and effective therapy for TTP.

Adult↗

PubMed1984

Development of DNA puffs and patterns of polypeptide synthesis in the salivary glands of Bradysia hygida.

In the three salivary gland regions of Bradysia hygida (Diptera, Sciaridae) the patterns of polypeptide synthesis, as revealed by electrophoresis and fluorography, are very stable during the fourth larval instar until about 30 h before the pupal molt. At this age the patterns of polypeptide synthesis start to undergo marked changes. The striking correlations between these changes and the development of two distinct groups of DNA puffs support the proposal that DNA puffs are causally related to the synthesis of specific proteins in the salivary glands.

Animals↗

PubMed1983