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Biomedical subjects

L Carrasco

Publications and source records attributed to L Carrasco.

At least 37 records · Page 2Linked to original sources
PubMed2002

Glomerulonephritis associated with simultaneous canine adenovirus-1 and Dirofilaria immitis infection in a dog.

This article describes a case of glomerulonephritis and immunocomplex (IgM, IgG and C3c) deposition in the mesangium and basement membranes of a 2-year-old dog with canine viral hepatitis and dirofilariasis. The deposits observed in the mesangium were in the vicinity of cells with viral replication. However, no clear relationship was found between viral replication and the deposition of immunocomplexes in the glomerular capillary basement membranes, which may be the reason why these deposits have only been tentatively related to the concomitant infestation by Dirofilaria immitis.

Adenoviridae Infections↗
PubMed2002

Early platelet aggregation as a cause of thrombocytopenia in classical swine fever.

Twenty pigs were inoculated with a virulent classical swine fever virus isolate to determine the mechanism responsible for thrombocytopenia using histopathologic, ultrastructural, and immunohistochemical (detection of viral antigens gp55 and FVIII-rag) techniques. In animals euthanatized at 2, 4, and 6 days postinoculation (dpi), clusters of granular material staining positive for FVIII-rag were observed in splenic cords, the marginal zone, hepatic sinusoids, and the perisinusoidal space. Moreover, numerous macrophages in these areas were swollen and displayed an intensely positive granular and cytoplasmic reaction. Cell alterations indicative of platelet activation and secretory and phagocytic activation of resident macrophages were also observed in these sites at 2 and 4 dpi. These results suggest that the thrombocytopenia observed in pigs is caused in the first instance by massive activation and subsequent phagocytosis of platelets secondary to the release of platelet-activating factors by activated macrophages.

Animals↗
PubMed2002

Immunolocalization of the smooth muscle-specific protein calponin in complex and mixed tumors of the mammary gland of the dog: assessment of the morphogenetic role of the myoepithelium.

The immunohistochemical expression of the smooth muscle-specific protein calponin was studied to assess the contribution of myoepithelial cells to the histogenesis of spindle cells of complex and mixed tumors of the mammary gland of the dog and the origin of cartilage and bone in mixed tumors. Formalin-fixed tissues from 55 benign and malignant tumors (49 also containing surrounding normal mammary gland) were evaluated. Periacinar and periductal myoepithelial cells of all the 49 normal mammary glands were diffusely stained by the anti-human calponin monoclonal antibody. Calponin was found in 53 (98%) of the tumors studied, reacting with the myoepithelium-like cells of 86% of benign tumors and their remnants in 85% of malignant tumors. Five different types of calponin-immunoreactive myoepithelial cells were identified: hypertrophic myoepithelial cells. fusiform cells, stellate myoepithelial cells, rounded (myoepithelial) cells, and chondroblasts. Differences in staining intensity and staining pattern among these five types of cells suggested a transition of myoepithelial cells to chondroblasts. Stromal myofibroblasts also showed calponin immunoreactivity, but they did not react with a cytokeratin 14 monoclonal antibody, which recognizes myoepithelial cells in mammary gland. Calponin appears to be a very sensitive marker of normal and neoplastic myoepithelium in the canine mammary gland, and its identification in different cell types of complex and mixed tumors of the mammary gland of the dog suggests a major histogenetic role for myoepithelial cells.

Animals↗
PubMed2001

HIV-1 protease cleaves eukaryotic initiation factor 4G and inhibits cap-dependent translation.

Several animal viruses inhibit host protein synthesis, but only some members of the picornavirus group are known to do so by cleaving translation initiation factor eIF4G. Here we report that infection of human CD4(+) cells with HIV-1 also leads to proteolysis of eIF4G and profound inhibition of cellular translation. Purified HIV-1 protease directly cleaves eIF4GI at positions 678, 681, and 1086, separating the three domains of this initiation factor. Proteolysis of eIF4GI by HIV-1 protease, as with poliovirus 2A protease, inhibits protein synthesis directed by capped mRNAs but allows internal ribosome entry site-driven translation. These findings indicate that HIV-1, a member of retrovirus group, shares with picornaviruses the capacity to proteolyze eIF4G.

Animals↗
PubMed2001

Entry of poliovirus into cells is blocked by valinomycin and concanamycin A.

Poliovirus contains a virus particle devoid of a lipid envelope that does not require an intact pH to enter into susceptible cells. Thus, the blockade of pH gradient generated in endosomes is not sufficient to impede the translocation of poliovirus particles to the cytoplasm, suggesting that translocation takes place at the plasma membrane. Measuring both viral protein synthesis and eIF4G-1 cleavage mediated by poliovirus protease 2A has been used to monitor productive entry of poliovirus into cells. Translation of the input poliovirus RNA produces enough 2A(pro) to cleave eIF4G-1, providing a sensitive assay to estimate poliovirus RNA delivery to the cytoplasm followed by its translation. Combination of concanamycin A, a vacuolar proton-ATPase inhibitor, and valinomycin, an ionophore that promotes K(+) efflux from cells, powerfully prevented poliovirus infection. Moreover, modifying the ionic conditions of the culture medium (increasing the concentration of K(+) and decreasing the concentration of Na(+)), together with concanamycin A, also significantly interfered with poliovirus entry. These findings suggest that poliovirus RNA requires an intact concentration of K(+) ions inside the cells to be uncoated and to gain access to the cytoplasm. In addition, the actual contribution of concanamycin A (as well as other inhibitors of endocytosis) to the total inhibition of productive poliovirus entry points to the idea that at least some percentage of polioviral subparticles translocates from the endosomes.

Anti-Bacterial Agents↗
PubMed2001

Human immunodeficiency virus type 1 VPU protein affects Sindbis virus glycoprotein processing and enhances membrane permeabilization.

The human immunodeficiency virus type 1 (HIV-1) Vpu is an integral membrane protein that forms oligomeric structures in membranes. Expression of vpu using Sindbis virus (SV) as a vector leads to permeabilization of plasma membrane to hydrophilic molecules and impaired maturation of wild type SV glycoproteins in BHK cells. The 6K protein is a membrane protein encoded in the SV genome that facilitates budding of virus particles and regulates transport of viral glycoproteins through the secretory pathway. Some of these functions were assayed with a SV mutant containing a partially deleted 6K gene. Transfection of BHK cells with pSVDelta6K vector rendered defective SVDelta6K virus, which had lower membrane permeabilization, impaired glycoprotein processing, and deficient virion budding. Replacement of 6K function by HIV-1 Vpu in SVDelta6K was tested by cloning the vpu gene under a duplicated late promoter (pSVDelta6KVpu). The presence of the vpu gene in the 6K-deleted virus enhances membrane permeability, modifies glycoprotein precursor processing, and facilitates infectious virus particle production. Restoration of infectivity of 6K-deleted SV by Vpu was evidenced by increased PFU production and cytopathic effect on infected cells. The modification of SVDelta6K glycoprotein maturation by Vpu was reflected in augmented processing of B precursor and impairment of PE2 cleavage. Taken together, our data support the notion that HIV-1 Vpu and SV 6K proteins share some analogous functions.

Animals↗
PubMed2001

A rapid and strong apoptotic process is triggered by hyperosmotic stress in cultured rat cardiac myocytes.

In all cell types, the maintenance of normal cell volume is an essential homeostatic function. Relatively little is known about the induction of apoptosis by hyperosmotic stress and its molecular mechanism in terminally differentiated cardiac myocytes. We compared the apoptotic response of cultured neonatal rat cardiomyoctes to hyperosmotic stress by sorbitol (SOR) with those induced by doxorubicin (Doxo) or angiotensin II (Ang II). We also examined the apoptotic-signaling pathway stimulated by the hyperosmotic stress. Apoptosis was assessed by the observation of: (1) cell viability, (2) DNA fragmentation detected by the TUNEL method and by agarose gel electrophoresis, and (3) poly(ADP-ribose)polymerase (PARP) degradation, and Bcl-XS and Bcl-XL levels by Western blot analysis. Exposure of cardiomyocytes to 0.3 M SOR for 24 h resulted in decreased cell viability and increased generation of oligosomal DNA fragments (2.5-fold of controls). At this time, 83 +/- 5% of SOR-treated myocytes were TUNEL-positive (vs 23.7 +/- 6.8% in controls; P<0.01). PARP levels also decreased by approximately 42% when cardiac myocytes were exposed to SOR. Hyperosmotic stress induced a more rapid and stronger apoptotic response in cardiomyocytes than Doxo or Ang II. In addition, SOR increased 3.2-fold Bcl-XS proapoptotic protein without changes in Bcl-XL antiapoptotic protein levels and in the p53-transactivating activity. Taken together, these results strongly suggest that hyperosmotic stress triggers cardiac myocyte apoptosis in a p53-independent manner, being earlier and stronger than apoptosis induced by Doxo and Ang II.

Angiotensin II↗
PubMed2001

Epithelioid blue naevus of the genital mucosa: report of four cases.

Epithelioid blue naevi are an unusual cytological variant of blue naevus that have been recently described mostly in patients with the Carney complex, although they may also occur in isolation. This variant of blue naevus is composed of melanin-laden polygonal epithelioid melanocytes situated within the dermis. The neoplastic cells show no maturation with progressive depth of dermal infiltration and, in contrast with the usual stromal changes in blue naevi, epithelioid blue naevi exhibit no dermal fibrosis. We describe four cases of epithelioid blue naevus located on the genital mucosa in four patients with no evidence of the Carney complex. Three male patients showed an epithelioid blue naevus on the mucosa of the glans penis and a female patient had a lesion of the right labium minoris. Histopathologically, the lesions consisted of entirely intradermal melanocytic naevi composed mostly of heavily pigmented epithelioid melanocytes involving the dermis of the genital mucosa. Immunohistochemically, in all cases, epithelioid melanocytes expressed immunoreactivity for S-100 protein, HMB-45, Melan-A and MiTF antibodies.

Adult↗
PubMed2001

Atypical cilia in the bronchiolar epithelium of pigs experimentally infected with hog cholera virus.

To study the effect of hog cholera virus on the epithelial cells of the bronchiolar mucosa, 12 pigs were inoculated with a highly virulent strain. Immunohistochemical and ultrastructural examination of the ciliated epithelial cells demonstrated an increase in the number of atypical cilia. The latter showed alterations in the microtubular pattern, possibly resulting from viral interference with the normal metabolism of the epithelial cells.

Animals↗
PubMed2001

Classical swine fever: pathogenesis of glomerular damage and immunocharacterization of immunocomplex deposits.

Twenty-six pigs were inoculated with a virulent isolate (Quillota strain) of classical swine fever (hog cholera) virus to determine the chronological development of lesions in the renal glomeruli and the pathogenesis of glomerular damage and immunocomplex deposition. The study included the use of histopathological, ultrastructural and immunohistochemical (detection of viral antigen gp55, myeloid-histiocyte antigen, IgM, IgG and C1q) techniques. The main changes in glomerular structure were observed from 7 days post-inoculation (dpi) onwards, at which time the glomeruli showed macrophage infiltrations in the mesangium, and viral infection in circulating cells, glomerular endothelial cells and podocytes. Moreover, significant subcellular changes were detected in podocytes, which appeared swollen, with fusion of foot processes. Immunocomplex deposits immunoreactive for IgM, IgG and C1q were detected in mesangial, subepithelial and subendothelial areas from 10 dpi, but viral antigen was not detected as a component of these deposits; fusion of foot processes had increased in severity, especially near immunocomplex deposits. All these changes had increased still further in the final phase of the experiment (14 dpi), with neutrophil infiltrations in the mesangium.

Animals↗
PubMed2001

Classical swine fever: morphological and morphometrical study of pulmonary intravascular macrophages.

To gain further insight into the pathogenesis of classical swine fever (CSF), the changes induced by hog cholera (HC) virus in pulmonary intravascular macrophages (PIMs) were examined. Twelve pigs were inoculated by the intramuscular route with a virulent strain of HC virus (Quillota strain) and killed in groups of three at 4, 7, 10 and 14 days post-inoculation. Immunohistochemical and ultrastructural examination revealed HC virus infection in endothelial cells, PIMs, and interstitial and alveolar macrophages. In addition to viral replication, a predominant feature was the secretory activation of PIMs, characterized by expanded rough endoplasmic reticulum and hyperplastic Golgi complexes. The results obtained suggest that macrophage activation and the subsequent release of pro-inflammatory mediators play an important role in the pathogenesis of CSF.

Animals↗
PubMed2001

Postirradiation pseudosclerodermatous panniculitis.

Pseudosclerodermatous panniculitis is an unusual variant of panniculitis that results as a complication of megavoltage radiotherapy. Four women developed this unusual entity on the anterior chest and abdominal skin after receiving megavoltage therapy for either breast carcinoma or painful bone metastases from breast carcinoma. Histopathologically, the epidermis and dermis of the involved area showed little or no evidence of radiodermatitis. The main findings were confined to the subcutaneous tissue and consisted of thickened, sclerotic septa composed of both thick and thin collagen bundles, and a lobular panniculitis characterized by lipophagic granulomas and scattered lymphocytes and plasma cells. Additionally, one of the cases showed markedly dilated vascular spaces with the appearance of lymphatics in the upper part of the dermis. Pseudosclerodermatous panniculitis after irradiation is an unusual cutaneous complication of megavoltage radiotherapy that should be distinguished from subcutaneous metastatic disease, cellulitis, or connective tissue diseases involving the subcutaneous fat. The differential diagnosis can be established on the basis of the characteristic histopathologic features of postirradiation pseudosclerodermatous panniculitis.

Adult↗
PubMed2001

Olmsted syndrome: report of a case with study of the cellular proliferation in keratoderma.

Olmsted syndrome is a rare disorder that consists of sharply marginated keratoderma of the palms and soles, constriction of digits and toes that may result in spontaneous amputation of the distal phalanges, hyperkeratotic plaques around the body orifices, onychodystrophy, and other less common cutaneous and extracutaneous anomalies. Although some patients had other affected family members, most cases of Olmsted syndrome seem to be of sporadic occurrence. We describe a patient with the characteristic features of Olmsted syndrome. The symptoms consisted of diffuse transgrediens palmoplantar keratoderma and keratotic plaques around the mouth and nose. Our patient also had the associated anomalies of hyperhidrosis of the palms and soles and congenital deaf-mutism. Histopathologic study of the keratoderma demonstrated epidermal hyperplasia with acanthosis, papillomatosis, and orthokeratotic hyperkeratosis. Immunohistochemical study showed more basal and suprabasal keratinocytes of the epidermis with immunoreactivity for Ki-67 marker when compared with the keratinocytes of the epidermis of the adjacent non-involved skin. These results support the notion that Olmsted syndrome is a hyperproliferative disorder of the epidermis.

Adult↗
PubMed2001

Sindbis virus variant with a deletion in the 6K gene shows defects in glycoprotein processing and trafficking: lack of complementation by a wild-type 6K gene in trans.

A Sindbis virus (SV) variant with a 6K gene partially deleted has been obtained. This SV Del6K virus is defective in the proteolytic processing of virus glycoprotein precursor, transport of glycoproteins to the plasma membrane, and plaque phenotype. A revertant virus (SV Del6K-revQ21L) containing a point mutation in the deleted 6K gene was isolated and characterized. SV Del6K-revQ21L has corrected the defects of proteolytic processing and transport of virus glycoproteins to the plasma membrane, but it still remains attenuated compared to wild-type (wt) SV, exhibiting defects in virus budding. Neither mutant nor revertant viruses are complemented by the coexpression in trans of a wt SV 6K gene.

Alphavirus Infections↗
PubMed2001

Antipoliovirus flavonoids from Psiadia dentata.

The search for antiviral agents against vesicular stomatitis virus, herpes simplex virus type 1 and poliovirus type 2 in plants extracts, led to the isolation of two antipoliovirus flavonoids from the medicinal plant Psiadia dentata (Cass.) DC, Asteraceae: 3-methylkaempferol and 3,4'-dimethylkaempferol. The antipoliovirus activity of both compounds was estimated by comparison with 3-methylquercetin, guanidine and Ro-090179. The most potent inhibitor of poliovirus replication was 3-methylkaempferol, and therefore we investigated its mechanism of action. We showed, using the inhibition of [3H]uridine incorporation in viral RNA and performing a dot-blot with one RNA probe specific for the poliovirus genomic strand RNA, that 3-methylkaempferol inhibits the genomic RNA synthesis of poliovirus.

Animals↗
PubMed2000

Poliovirus induces apoptosis in the human U937 promonocytic cell line.

The human promonocytic U937 cell line, which is moderately susceptible to poliovirus infection, has been used to investigate the induction of apoptosis by this virus. Infection of U937 cells with poliovirus induces morphological changes typical of apoptosis. Poliovirus-resistant U937 cells (PRU) have been isolated that are resistant to apoptosis induced by poliovirus, but that undergo apoptosis after treatment with TNF plus cycloheximide. Despite the fact that poliovirus triggers nitric oxide production in U937 cells, the inhibitor of inducible nitric oxide (NO) synthase, N(omega)-monomethyl-l-arginine, did not hinder apoptosis after infection, suggesting that NO does not play a direct role in this process. Finally, poliovirus infection of U937 cells led to the cleavage of pro-caspase-3 and poly(ADP-ribose)polymerase, indicating the activation of the CPP32 ICE-like cysteine protease in the induction of apoptosis. Our findings suggest that cellular death takes place in U937 cells productively infected by poliovirus as a result of apoptosis and involves caspase activation.

Apoptosis↗
PubMed2000

Contribution of the outpatient surgery unit ITO the general surgery department of a district hospital.

Introduction: The creation of Outpatient Surgery (OPS) units to combine the quality of medical attention and rationalize costs allows for greater efficiency in the use of resources. Aim: To report our series of patients undergoing surgery at the OPS units integrated into our Hospital (Type II): Patients and method: Between May 1994 and March 1998, 832 outpatients, of a total of 5230, underwent surgery at our General Surgery Unit. The criteria for exclusion from the programme depended on the patient and the enviroment or resulted from the operation itself. Results: Mean patient age was 47.5 years; there were 420 males and 412 females. Surgery was performed for 229 inguinofemoral hernias, 47 umbilical-epigastric hernias, nine incisional hernias, 193 pilonidal sinuses, 156 mammary nodules, 65 varicose veins, 64 arteriovenous fistulae and 69 proctology operations. The most common anesthesia techniques performed were rachianesthesia and local anesthesia. Eight point seven percent of the patients required admission (OPS failure), the most frequent causes being excessive pain, orthostatic-syncopal hypotension, nausea and vomiting and urine retention. There was no morbidity or mortality. Conclusion: OPS is a highly efficient procedure for resolving the most common pathologies in General Surgery. The anesthesia technique was an important factor in the rate of failure.

Journal Article↗