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Biomedical subjects

G Bernardini

Publications and source records attributed to G Bernardini.

62 records · Page 4Linked to original sources
PubMed1983

A hyperpolarization-activated chloride current in Xenopus laevis oocytes under voltage-clamp.

Voltage-clamp experiments have been performed on ovulated Xenopus laevis oocytes. Two kinds of oocytes were studied: mature oocytes presenting the white spot due to germinal vesicle breakdown (GVBD) were found to be essentially unexcitable; oocytes without the white spot appeared to possess ionic channels which open transiently on hyperpolarization. The current is carried by chloride ions and, in Holtfreter's solution, has a reversal potential at approximately - 15 mV.

Animals↗
PubMed1981

Healing-over in rat crystalline lens.

1. 42K efflux has been studied in normal and injured rat crystalline lenses to test their ability to heal over. Following injury, a sizeable, but transient, increase in fractional loss of 42K takes place. 2. The lens healing-over is Ca-dependent and cannot be accounted for by membrane resealing. This is excluded by the fact that Procion Yellow gains access to damaged fibres even 2 hr after injury (when the healing-over is completed). 3. The occlusion of the junctional channels is the basic mechanism of healing-over. This is supported by the observation that Procion Yellow does not diffuse from damaged to intact fibres and by the Ca dependency of the phenomenon.

Animals↗
PubMed1981

Gap junction crystallization in lens fibers after an increase in cell calcium.

Previous studies have shown that cell uncoupling is paralleled by an increase in tightness and crystallinity of gap junction particle arrays. Gap junction crystallinity is believed to be part of the uncoupling mechanism because it can be produced in gap junctions isolated from lens fibers on direct exposure to uncoupling agents such as divalent cations or hydrogen ions. Some doubts, however, have been raised on the capacity of lens fiber junctions to crystallize and uncouple in situ. The present study shows that the gap junctions of rat lens fibers indeed crystallize after a treatment that increases drastically the membrane permeability to ions. The treatment consists of a brief immersion of the lenses in liquid nitrogen, followed by incubation for several hours in Tyrode's solution at 37 degrees C. Immediately after liquid nitrogen treatment, the lenses start gaining sodium and calcium while losing potassium, and eventually become opaque. Addition of 10 mM EDTA to calcium and magnesium-free Tyrode's solutions inhibits particle crystallization and lens cataract, whereas low concentrations of EDTA (1 mM) are not effective. These findings, together with preliminary data on the capacity of lens fibers to heal over, indicate that the gap junctions of lens fibers are capable of crystallizing and uncoupling in situ.

Animals↗
PubMedDate not supplied

[Evaluation and quantification of biologic risk in the hospital setting with ATP determination on work surfaces].

The purpose of this study was to establish whether a method of determining ATP levels using the HY-Lite system could be reliably applied in the various hospital workplaces. We estimated the correlation between ATP levels and the number of C.F.U. (Colony Forming Units), observed correlation r = 0.96. We established hygienically acceptable values for each environment, and drew up reference tables. The study reveals that conditions of high bacterial and fungine contamination can occur, albeit the agents are not normally pathogenic is so far as they consist of common environmental pollutants. Consequently, these results emphasize the need to apply strict sanitization and hygienic measures, that health workers must be suitably trained to deal with follow. The results of the sampling appear to suggest that condition of potential biological risk for workers are largely due to incorrect work procedure in workplaces where pathologic agents are present.

Adenosine Triphosphate↗
PubMedDate not supplied

Natural killer cells and gamma/delta T cells in synovial fluid and in peripheral blood of patients with psoriatic arthritis.

OBJECTIVE: NK surface markers and gamma/delta TCR antigen are involved in non-MHC-restricted cytotoxicity, which represents a major effector mechanism of the cell-mediated immune response. We evaluated in PsA patients SF and PB lymphocytes expressing these cellular subsets in order to obtain information on the possible role played by them in the disease. METHODS: We studied 29 PsA and 27 RA patients, as well as 27 healthy controls. In 17 PsA and 16 RA patients with knee joint effusion, analysis of SF was performed. SF and PB lymphocyte analysis was performed by direct dual immunofluorescence flow cytomettry using anti-CD3, anti-CD4, anti-CD8, anti-CD19, anti-TCR-gamma/delta-1 and anti-CD16 and anti-CD56 monoclonal antibodies. RESULTS: PsA and RA patients had, with respect to controls, lower values (both as percentages and in absolute numbers) of PB T cells expressing gamma/delta TCR. SF Iymphocytes of PsA and RA patients were characterised, as compared to PB lymphocytes, by lower numbers (both in absolute numbers and in relative terms) of NK and NK-T cells. Considering the absolute numbers of the various lymphocyte subsets, a strong correlation was found in PsA SF between gamma/delta T cells and NK (p < 0.0007) or NK-T cells (p < 0.0003), as well as between NK and NK-T cells (p < 0.0019). There was instead no statistically significant correlation among the different SF or PB lymphocytes and the most relevant clinical or serological parameters. CONCLUSION: This study, analyzing the impairment of different subsets involved in non-MHC-restricted cytotoxicity, suggests that this component of the cell-mediated immune response seems to play a pivotal role in the development of PsA.

Adolescent↗