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Biomedical subjects

L Villa

Publications and source records attributed to L Villa.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Expanding drug resistance through integron acquisition by IncFI plasmids of Salmonella enterica Typhimurium.

We conducted a 30-year retrospective analysis of IncFI plasmids from Salmonella enterica serotype Typhimurium. These plasmids have been associated with the emergence of epidemic clones of multidrug-resistant Salmonella. Molecular and genetic evidence indicates that IncFI plasmids are evolving through sequential acquisition of integrons carrying different arrays of antibiotic- resistance genes.

Drug Resistance, Microbial↗
PubMedDate not supplied

[Human papillomavirus associated with uterine cervix lesions].

It was studied the prevalence of human papillomavirus (HPV) among 228 women with lesions of uterine cervix attending the Ofir Loiola Institute, in Belem, Para, from March 1992 to May 1996. Histopathological examination was performed with all cervical biopsy samples obtained from these patients. In addition, specimens were analysed by both polimerase chain reaction and dot-blot hybridization to detect HPV DNA. The patients were assigned to three groups, according to the diagnosis made by histopathology, as follows: A, including 155 women suffering from invasive epidermoid carcinoma or adenocarcinoma; B, 54 patients having either cervical intraepithelial neoplasia grade II or III; and C, involving 19 women with chronic cervicitis. The prevalence rates of HPV in groups A, B and C were 70.3%, 63% and 36.8% respectively. HPV 16 accounted for 60.4% and 54.5% of types identified in groups A and B, respectively. Altogether HPV types 16, 18 and 33 were detected in 71.4% of positive patients belonging to group C.

Biopsy↗
PubMedDate not supplied

[Neurobehavioral effects of inhalation anesthetics used occupationally: a critical analysis].

Unlike other apparatuses, the potential effects on the nervous system of occupational exposure to anaesthetic gases have not been exhaustively reviewed. Because of the relevance of these effects, their significance of the quality of life of the exposed subjects and of the increased risk inherent in their delicate work tasks, these themes deserve the greatest attention. This paper briefly examines the data from the international literature as well as the neurobehavioral methods employed, underlines the existing gaps of knowledge and eventually proposes strategies aimed at filling these gaps of knowledge.

Anesthesia, Inhalation↗
PubMedDate not supplied

Mechanism of acute toxicity of IL-1 beta in mice.

Human recombinant IL-1 beta was able to kill C3H/HeJ mice only when inoculated intravenously at very high doses. IL-1 beta, inoculated at 100 mg/kg i.v. as a bolus, induced a shock-like state characterized by anorexia, severe hypothermia and hypoglycemia and persistent neutrophilia, leading to death in 55% of animals generally between 24 and 48 h. In contrast, the noninflammatory adjuvant IL-1 beta peptide VQGEESNDK (position 163-171) did not induce any toxic effect in vivo, when administered following the same schedule. At variance with what was previously observed in endotoxin induced shock, IL-1 beta induced death was not preceded by appearance of circulating TNF. On the other hand, very high and persistent levels of circulating IL-6 could be detected after lethal IL-1 beta administration. Treatment of mice with ibuprofen or with chlorpromazine, both known to counteract some of the toxic effects of IL-1 in vivo, could protect from IL-1 beta induced mortality. Both drugs, at doses protecting from IL-1 beta induced death, were able to abolish IL-1 beta-induced rise of circulating phospholipase A2 (PLA2) activity, and the subsequent generation of toxic PLA2-derived metabolites.

Amino Acid Sequence↗
PubMedDate not supplied

Defining the structural requirements of a biologically active domain of human IL-1 beta.

The immunostimulatory activity in vivo of the pleiotropic cytokine IL-1 beta can be retained by its nonapeptide VQGEESNDK, in position 163-171. A series of shorter and longer peptides around this position has been assayed for IL-1-like biological activity, in order to identify the structural requirements for full expression of adjuvant capacity. Elongated peptides, comprising the loop region 165-169 and up to six amino acids in the preceding beta strand or up to seven amino acids in the following beta strand, showed activity comparable or lower than that of the nonapeptide 163-171. This would indicate that the beta strand sequences are not required for optimizing the active conformation of the immunostimulatory IL-1 beta moiety. Accordingly, stabilization of the 163-171 peptide conformation by cyclization did not increase its biological activity. In contrast, the pentapeptide GEESN, corresponding the exposed loop 165-169 between two beta strands, had biological activity higher than that of the 163-171 nonapeptide and fully comparable to that of the entire IL-1 beta protein. Thus, the highly exposed fragment 165-169 within the IL-1 beta molecule may be the structure selectively responsible for the IL-1 beta immunostimulatory capacity in vivo.

Adjuvants, Immunologic↗
PubMedDate not supplied

Peyer's patch lymphocytes express natural cytotoxicity but not natural killer activity.

The distribution of natural cytotoxic (NC) cells in the gut-associated lymphoid tissues (GALT) and in peripheric lymphoid organs was analyzed in comparison to that of natural killer (NK) cells. It was found that cells from the intestinal epithelium, mesenteric lymph nodes and spleen possess significant levels of NC and NK activity, whereas in thymus and popliteal lymph nodes both the natural activities are negligible. As previously shown for splenocytes, the NC activity of GALT cells is detectable in the 16-hour assays and not in the 4-hour assays. Interestingly, Peyer patches lymphocytes (PPL) possess extremely high NC activity but no NK activity. The NC activity of PPL is still high in NK-deficient mouse strains such as A/J and SJL/J. To further support the observation that the effector PPL are truly NC cells, it was shown that, as previously reported for spleen NC activity, overnight incubation at 37 degrees C of the lymphocytes only marginally affected the cytotoxicity of PPL, which could in turn be augmented by interleukin-3 (IL-3) containing supernatants. On the contrary, IL-2 could not increase NC or NK activity by PPL whilst augmenting NK activity of splenocytes. Thus, for the first time a cell population is identified which expresses only NC activity and not NK and which can be positively regulated only by IL-3.

Animals↗