Search PubMed⌕ Search

Biomedical subjects

J Esparza

Publications and source records attributed to J Esparza.

At least 109 records · Page 6Linked to original sources
PubMed1980

Preliminary characterization of virus-like particles in a mosquito (Aedes pseudoscutellaris) cell line (Mos. 61).

Electron microscopic examination of an Aedes pseudoscutellaris mosquito cell line (Mos. 61) revealed the presence of a large number of virus-like particles (VLP) in the cytoplasm of approximately 10% of the cells. These particles have a diameter of 36 nm, do not contain a lipid envelope, and have a buoyant density of 1.40 g/ml in CsCl. VLP contain DNA which appears to be single-stranded by SU nuclease assay. PAGE of the VLP demonstrates the presence of four structural polypeptides with molecular weights of 52K, 70K, 75K and 100K daltons, the smaller one being the majro polypeptide species and accounting for 71% of the the total protein mass. The A. pseudoscutellaris VLP appear to share some, but not all, of the characteristics of the genus Densovirus, family Parvoviridae. Their possible biologic importance and taxonomic location are still unclear.

Aedes↗
PubMed1979

Central nervous system alterations as sequelae of Venezuelan equine encephalitis virus infection in the rat.

Alterations of the Central Nervous System (CNS) in rats surviving acute infection with a virulent strain of Venezuelan Equine Encephalitis (VEE) virus were studied by light and electron microscopy. Cavitary necrosis of the cerebral cortex, macrophage activity and degenerative axonal changes were considered to be sequelae of the lesions induced during the acute phase of the infection. Mononuclear cell infiltrates of the neuropil, 3 mth after inoculation, were related to the immune response of the host. Focal lesions and mononuclear cell activity in the brain are thought to be the equivalent of the lesions induced in the CNS of humans during VEE virus infection. The findings are discussed in the light of recent reports of cerebral dysfunction occurring as a sequel of VEE virus infection in children.

Animals↗
PubMed1979

Tetracycline-mediated photodynamic inactivation of animal viruses.

Demethylchlortetracycline (DMCT), doxycycline and, to a lesser extent, chlortetracycline were capable of mediating the in vitro photoinactivation of Venezuelan equine encephalitis (VEE) virus. Other tetracyclines tested were found to be inactive in this respect. However, no correlation between chemical structure and photosensitizing activity could be established. The photoinactivation of VEE virus by DMCT proceeds through a photodynamic mechanism as shown by the absolute requirement of O2 for the inactivation to take place. The photoinactivating effect of DMCT was also exerted upon other animal viruses tested, i.e. vesicular stomatitis virus, herpes simplex virus and poliovirus, even when, in the case of poliovirus, the capsid seems to be impermeable to the tetracycline. The fact that the two most effective photosensitizing tetracyclines for VEE virus are also the drugs more frequently associated with drug-induced phototoxicity in humans, suggests that virus photoinactivation could be used as a screening procedure for potentially phototoxic drugs developed for human application.

Chemical Phenomena↗
PubMed1978

[Intestinal amebiasis in children. I. Etiological study of colonic lesions of the rectosigmoid colon].

A total of 253 children from two months to 12 years old, who had diarrheic or dysenteric syndromes, were studied from the rectosigmoidoscopic and parasitologic points of view. In addition, 112 and 20 of these patients were also studied bacteriologically and virologically, respectively. Only in 28 patients torphozoites of Entamoeba histolytica were found by means of direct microscopic examination, staining techniques and amoebal cultures. Enteropathogenic bacteria were isolated in 41 of the 112 cases examined. No viral particles were detected in the 20 cases studied. From the discussion of these results, the conclusion is reached that the rectosigmoidal mucusal alterations which have been currently considered as suggesting amoebal lessions are not characteristic of invasive intestinal amebiasis in children.

Child↗
PubMed1978

Vetebral hemangiomas: spinal angiography and preoperative embolization.

Seven cases of symptomatic spinal hemangiomas are discussed. Special emphasis is given to a patient in whom pre-operative embolization was necessary. A marked reduction in the blood supply was achieved, with the result that the subsequent laminectomy was carried out without great difficulty.

Adolescent↗
PubMed1977

Induction of Venezuelan equine encephalitis (Mucambo) virus by iododeoxyuridine in chronically infected 'cured' cultured mosquito cells.

Infection of cultured Aedes aegypti mosquito cells with Venezuelan equine encephalitis virus (Mucambo subtype) results in the establishment of a chronic non-cytopathic infection. Infected cells could be 'cured' when they were grown in the presence of immune serum for 3-4 passages. 'Cured' cells could then be subcultured repeatedly, in the absence of immune serum, without showing any indication of infectious virus production. When 'cured' cells were exposed to 50 microgram/ml of 5-iodo-2-deoxyuridine for 24 h, efficient induction of virus was observed. The enhancement of virus replication could not be related with increased susceptibility of the uninfected cell population. The phenotype (plaque size and virulence) of the induced virus resembles more closely that of the standard virus than the phenotype of the virus produced in chronically infected mosquito cells. These findings indicate that virus information can be maintained in chronically infected mosquito cells in a latent inducible form, and constitute indirect evidence suggesting the existence of a DNA provirus in this system.

Aedes↗
PubMed1977

Rotaviruses in Venezuelan children with gastroenteritis.

Rotaviruses were identified by electron microscopy in 19 of 26 (73%) Venezuelan children with gastroenteritis. Noncultivable adenoviruses and small (29-30 nm), spherical viruses were also observed in a few cases. Bacterial pathogens were isolated from five children (19%), all of whom were also carrying rotaviruses.

Adenoviruses, Human↗
PubMed1977

Os odontoideum removed by a transoral approach.

A case of atlanto-axial dislocation secondary to the presence of an "Os Odontoideum" is reported in which there was no history or evidence of trauma before the onset of symptoms. The treatment of this unusual clinical condition is discussed.

Axis, Cervical Vertebra↗
PubMed1976

Multiplication of vesicular stomatitis virus in the leafhopper Peregrinus maidis (Ashm.), a vector of a plant rhabdovirus.

Vesicular stomatitis virus (VSV) was found to multiply efficiently in whole Peregrinus maidis (Ashm.). the leafhopper vector of maize mosaic virus (MMV), a plant rhabdovirus. Insects were inoculated with VSV by means of a microsyringe, collected at 1-day intervals and tested individually for the presence of virus. Exponential virus multiplication occurred within the first 4 days, reaching titres of 10(6) p.f.u. per insect in days 5 to 10 after inoculation. These observations show that a common host is avialable to study the multiplication of a plant and an animal rhabdovirus.

Animals↗
PubMed1975

Multiplication of Venezuelan equine encephalitis (Mucambo) virus in cultured mosquito cells.

Venezuelan Equine Encephalitis (Mucambo) virus was able to multiply at 28degree C in cultured mosquito cells (Aedes aegypti and Aedes albopictus) without inducing any apparent cytopathology. The kinetics of virus multiplication was similar in mosquito and mammalian (Vero) cells. Twelve to twenty four hours post-infection, a maximum of 10-50 per cent of the cells were engaged in virus production; however, almost immediately this proportion fell abruptly tending to stabilize in the order of 0.01 to 0.05 per cent. No significant increase of infectious centers was observed after cell subculturing. Study of subpopulations of mosquito cells revealed a differential suceptibility to virus infection, which suggests that a balance of susceptible and virus resistant cells may play a role in the establishment and persistence of the chronic infection.

Aedes↗
PubMed1975

Viral gene functions expressed and detected by temperature-sensitive mutants of herpes simplex virus.

The expression of HSV-specific gene functions by 22 ts mutants of HSV-1 in 15 complementation groups and 8 ts mutants of HSV-2 in 7 complementation groups has been studied at the nonpermissive temperature. Four cistrons of HSV-1 and three cistrons of HSV-2 with defects in viral DNA and DAN polymerase synthesis were identified. DNA-mutants of HSV-1 revealed a greater alteration in HSV polypeptide synthesis and viral assembly than DNA- mutants of HSV-2. Mutants with apparent defects in structural proteins have been identified for both HSV-1 and HSV-2 as demonstrated by their increased themolability. The general organization of the provisional HSV-1 and HSV-2 linkage maps revealed a similarity in the arrangement of functionally related cistrons, with DNA- mutants being located on the left-hand side of each map and mutants with phenotypic properties similar to those of the wild-type virus, on the right-hand side. An early polypeptide of HSV (VP175, MW 175,000) was found to accumulate in cells infected at the nonpermissive temperature withts mutants of HSV-1 in complementation group B. The VP175 polypeptide was isolated from such cells by a combination of SDS-preparative and analytical disc gel electrophoresis. Antiserum prepared to this polypeptide was found to descriminate between HSV-1 and HSV-2 by immunofluorescence. On the other hand, type-specific gene functions of HSV-1 and HSV-2 were not demonstrated through intertypic complementation and recombination tests with heterologous mutant pairs, whereas mutually exchangeable or common gene functions were readily identified. Eight ts mutants of HSV-2 were used to detect functional HSV genes in hamster embryo cells transformed by HSV-2. Normal hamster cells and SV40-transformed hamster cells failed to support the replication of the mutants at the nonpermissive temperature. However, the replication of two mutants, defective in late functions, was significantly enhanced in two independently derived HSV-2-transformed cell lines. Thus functional HSV genetic information was detected in HSV-2-transformed cells through the use of ts mutants. Moreover, it appears that the information present in both cell lines is not only specific but involves late HSV functions.

Antigens, Viral↗