Biomedical subjects

Antonio Medina

Publications and source records attributed to Antonio Medina.

5 recordsLinked to original sources

PubMed2006

Spermatozoal ultrastructure in three Atlantic solenocerid shrimps (Decapoda, Dendrobranchiata).

The spermatozoal ultrastructure in three solenocerid shrimps (Solenocera membranacea, S. africana, and Pleoticus muelleri) from different Atlantic locations was examined with the aim of increasing understanding of the phylogenetic relationships in the Dendrobranchiata. A considerable structural similarity between the sperm of these species and those of penaeid shrimps supports a close affinity between the Penaeidae and Solenoceridae. However, significant differences in the sperm morphology of the previously investigated sicyoniids (namely, a greater complexity of the acrosomal complex) suggest evolutionary separation of the Sicyoniidae from the assemblage Penaeidae-Solenoceridae. Two ultrastructural features distinguish the spermatozoa of the three studied solenocerids from penaeid sperm: 1) separation of the plasma and acrosome membranes at the base of the spike and anterior region of the cap, and 2) asymmetry of the acrosomal cap, which appears to be a synapomorphy of the group. No striking ultrastructural differences were found between the spermatozoa of the closely related species S. membranacea and S. africana, whereas a great number of morphological differences separate the spermatozoa of Pleoticus from those of Solenocera (e.g., shape of the acrosomal cap, structural arrangement of the contents of the whole acrosome vesicle, thickness and distribution of the cytoplasm, and external shape of the spike).

Animals↗

PubMed2006

[Hepatocarcinoma in noncirrhotic liver].

Hepatocellular carcinoma (HCC) usually develops in patients with liver cirrhosis or chronic liver disease. These tumors are highly infrequent in patients without precipitating factors. We present a series of four patients with nonfibrolamellar HCC arising in healthy liver. None of the patients had viral infection, or showed alcohol abuse and/or hemochromatosis. Three patients underwent surgery. The clinical characteristics, therapeutic options, and survival and recurrence rates in this type of tumor are discussed.

Adult↗

PubMed2006

Compact laser radar and three-dimensional camera.

A novel three-dimensional (3D) camera is capable of providing high-precision 3D images in real time. The camera uses a diode laser to illuminate the scene, a shuttered solid-state charge-coupled device (CCD) sensor, and a simple phase detection technique based on the sensor shutter. The amplitude of the reflected signal carries the luminance information, while the phase of the signal carries range information. The system output is coded as a video signal. This camera offers significant advantages over existing technology. The precision in range is dependent only on phase shift and laser power and theoretically is far superior to existing time-of-flight laser radar systems. Other advantages are reduced size and simplicity and compact and inexpensive construction. We built a prototype that produced high-resolution images in range the (z) and x-y.

Journal Article↗

PubMed2005

Ultrastructure of oogenesis in the bluefin tuna, Thunnus thynnus.

Ovarian ultrastructure of the Atlantic bluefin tuna (Thunnus thynnus) was investigated during the reproductive season with the aim of improving our understanding of the reproductive biology in this species. The bluefin, like the other tunas, has an asynchronous mode of ovarian development; therefore, all developmental stages of the oocyte can be found in mature ovaries. The process of oocyte development can be divided into five distinct stages (formation of oocytes from oogonia, primary growth, lipid stage, vitellogenesis, and maturation). Although histological and ultrastructural features of most these stages are similar among all studied teleosts, the transitional period between primary growth and vitellogenesis exhibits interspecific morphological differences that depend on the egg physiology. Although the most remarkable feature of this stage in many teleosts is the occurrence of cortical alveoli, in the bluefin tuna, as is common in marine fishes, the predominant cytoplasmic inclusions are lipid droplets. Nests of early meiotic oocytes derive from the germinal epithelium that borders the ovarian lumen. Each oocyte in the nest becomes surrounded by extensions of prefollicle cells derived from somatic epithelial cells and these form the follicle that is located in the stromal tissue. The primary growth stage is characterized by intense RNA synthesis and the differentiation of the vitelline envelope. Secondary growth commences with the accumulation of lipid droplets in the oocyte cytoplasm (lipid stage), which is then followed by massive uptake and processing of proteins into yolk platelets (vitellogenic stage). During the maturation stage the lipid inclusions coalesce into a single oil droplet, and hydrolysis of the yolk platelets leads to the formation of a homogeneous mass of fluid yolk in mature eggs.

Animals↗

PubMed2003

[Testicular microlithiasis and testicular cancer].

OBJECTIVE: To check the possible relationship between testicular microlithiasis and testicular carcinoma in a patient in the one which previously we discovered a sonographic image of this condition. The etiopathogenesis, incidence and attitude are discussed. METHODS: A 23-year-old male with a psychomotor retardation secondary to a chromosomopathy presented with orchitis. Scrotal ultrasound discovered testicular microlithiasis, described as many hyperechoic images. Thirteen months later a testicular cancer was found in a new ultrasound. Radical orchiectomy was performed. Currently the patient is under intense follow-up. RESULTS: The histopathological study showed mature teratoma and intratubular germ cell neoplasm. CONCLUSIONS: The testicular microlithiasis has been related with benign and malignant testicular pathology. However, this presence it is not sufficiently clarified and the urologist's attitude to a patient with testicular microlithiasis but asymptomatic is not enough studied.

Adult↗