The K+ conductance of the inner mitochondrial membrane. A study of the inducible uniport for monovalent cations.

Addition of A23187 plus EDTA to rat liver mitochondria induces a common uniport pathway for monovalent cations. In this study, we have carried out a detailed characterization of the flow/force relationship for K+ transport along this pathway under steady state conditions. In the presence of EDTA, the K+ conductance is a linear function of external K+ in the range 0-20 mM K+, with a slope of 0.15 nmol of K+ x mg of protein-1 x min-1 x mV-1. The K+ conductance is inhibited by Mg2+ in the range 10(-9)-10(-6) M, while K+ flux is stimulated by the sulfhydryl group reagent mersalyl. Uniport activity can be detected in native mitochondria. These findings are compatible with the notion that electrophoretic K+ flux across the inner membrane takes place via a regulated K+ uniport with the potential of transporting K+ at rates in excess of 600 nmol x mg of protein-1 x min-1

Interactions of Cyclophilin with the Mitochondrial Inner Membrane and Regulation of the Permeability Transition Pore, a Cyclosporin A-sensitive Channel

Mammalian mitochondria possess an inner membrane channel, the permeability transition pore (MTP), which can be inhibited by nanomolar concentrations of cyclosporin (CS) A. The molecular basis for MTP inhibition by CSA remains unclear. Mitochondria also possess a matrix cyclophilin (CyP) with a unique N-terminal sequence (CyP-M). To test the hypothesis that it interacts with the MTP, we have studied the interactions of CyP-M with rat liver mitochondria by Western blotting with a specific antibody against its unique N terminus. Although sonication in isotonic sucrose at pH 7.4 releases a large proportion of CyP-M, a sizeable CyP-M fraction sediments with submitochondrial particles at 150,000 × g. We show that the interactions of this CyP-M pool with submitochondrial particles are disrupted (i) by the addition of CSA, which inhibits the pore, but not of CSH, which does not, and (ii) by acidic pH condition, which also leads to selective inhibition of the MTP; furthermore, we show that the effect of acidic pH on CyP-M binding is prevented by diethylpyrocarbonate, which fully prevents the inhibitory effect of H+ on the MTP (Nicolli, A., Petronilli, V., and Bernardi, P.(1993) Biochemistry 32, 4461-4465). These data suggest that CyP-M binding is involved in opening of the MTP and that pore inhibition by CSA and protons may be due to unbinding of CyP-M from its putative binding site on the MTP. A role for CyP-M in MTP regulation is also supported by a study with a series of CSA derivatives with graded affinity for CyP. We show that with each derivative the potency at inhibition of the peptidylprolyl cis-trans-isomerase activity of CyP-M purified to homogeneity is similar to that displayed at inhibition of MTP opening, relative to that displayed by CSA. Decreased binding to CyP-M (but not CyP-A) and decreased efficiency at MTP inhibition is obtained by substitutions in position 8 while a 4-substituted, nonimmunosuppressive derivative is as effective as the native CSA molecule, indicating that calcineurin is not involved in MTP inhibition by CSA

Significance of anti-HB levels below 10 IU/L after vaccination against hepatitis B in infancy or adolescence: an update in relation to sex

Hepatitis B vaccination (three-dose series) induces long-term immunity, but it is not uncommon to find antibody levels below 10 IU/L long after vaccination. However, the majority of the subjects with low antibody levels have a prompt response to a booster dose. A population of 10,294 students at Padua University Medical School, who were subjected to hepatitis B vaccination during infancy or adolescence according to the law, was tested for the presence of anti-HBs, usually during the first year of matriculation. Among the students offered a booster dose, 1,030 were vaccinated, and the antibody titre was re-tested. The present research provides further evidence from a larger number of students (1,030) that an anti-HB level higher than 2 IU/L is predictive of a prompt response to a booster. There are also differences related to sex. The results clearly confirm that an antibody titre equal to or greater than 2 IU/L is enough to prompt a response after a booster dose, even several years after the initial vaccination cycle, and to predict effective immune protection. The length of the interval between the booster/post-booster analyses increases the probability of finding a low response to the booster; furthermore, females show a more rapid response to the booster than males. The importance for healthcare workers of measuring the antibody titre four weeks after a booster is highlighted, and the results suggest that females have a better response than males to booster vaccination

Varicella seroepidemiology and immunization in a cohort of future healthcare workers in the pre-vaccination era

Objectives: The goal of this study was to establish the seroprevalence of positive antibodies against varicella and compliance with varicella vaccination in the pre-vaccination era. Methods: A cohort of 10 683 Italian students from Padua University Medical School (from 2004 to 2019) were enrolled and classified as unvaccinated, vaccinated once, or vaccinated twice against varicella, according to their vaccination certificate. The antibody titre was measured and the seroprevalence of positive subjects was determined. Subjects with negative or equivocal antibodies were invited for vaccination, and then the antibody titre was retested. Results: Unvaccinated students were mostly seropositive (95.6%), compared with vaccinated students who were less seropositive (68.0% after one dose and 78.6% after two doses) and had significantly lower antibody titres (p < 0.0001). The post-test vaccination had a positive response rate of 85.4%: 67.4% after one dose and 91.4% after two doses. Conclusions: In the pre-vaccination era, only 3.3% of future healthcare workers were vaccinated against varicella (1.1% once and 2.2% twice). Vaccination or revaccination of negative and equivocal individuals could reduce the number of susceptible people. Implementation of varicella vaccine (two doses) in healthcare workers is of primary importance to reduce the risk of transmission

Biological Monitoring of Metal Ions Released from Hip Prostheses

The aim of this study was to evaluate the levels of As, Be, Bi, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, Tl, V, and Zn, by inductively coupled plasma-mass spectrometry (ICP-MS) in the urine of two groups of patients with two different types of metal-on-metal (MoM) total hip prostheses (ASR DePuy\uae, group A, 25 patients; total Met-Met System Lima\uae, group B, 28 patients). The determination of metals reflected a steady-state release (group A: 9 years after surgery and group B: 6 years after surgery). The results obtained confirmed the increase of Co and Cr urinary levels in both group when compared with the reference values for the general population adopted by the Italian Society of Reference Values (SIVR). In particular, Co and Cr levels exceeded the threshold values in urine, respectively, of 30 \u3bcg and 21 \ub5g, adjusted to creatinine based on the threshold in whole blood of 7 \u3bcg/L proposed by the Medicines and Healthcare Products Regulatory Agency (MHRA). Regarding the other investigated metals, significantly higher values were found in Group A than in Group B. These differences could be due to the type of hip prosthesis implanted, the longer period of time since the implantation, as well as many other factors such as diet, age, drug consumption, physical activity, or presence of dental fillings. The continuous monitoring over the years of metal concentrations in patients carrying a prosthesis could be useful to better identify the sources of these metals

Will We Have a Cohort of Healthcare Workers Full Vaccinated against Measles, Mumps, and Rubella?

Healthcare workers are a population exposed to several infectious diseases, and an immunization programme is essential for the maintenance of good vaccination coverage to protect workers and patients. A population of 10,653 students attending degree courses at Padua Medical School (medicine and surgery, dentistry and health professions) was screened for vaccination coverage and antibody titres against rubella, mumps, and measles. The students were subdivided into five age classes according to their date of birth: those born before 1980, between 1980 and 1985, between 1986 and 1990, between 1991 and 1995, and after 1995. Vaccination coverage was very low in students born before 1980, but the rate of positive antibody titre was high due to infection in infancy. Increasing date of birth showed increased vaccination coverage. In contrast, immune coverage was high for rubella (more than 90%) but not for mumps and measles (approximately 80%). An "anomaly" was observed for mumps and measles in the cohort born between 1991 and 1995, probably due to the trivalent vaccine formulation. Students born after 1990 showed vaccination coverage that exceeded 90%. It is therefore very likely that we will have a future generation of healthcare workers with optimal vaccination coverage

Unusual Domestic Source of Lead Poisoning

Non-occupational lead poisoning is not rare, mainly occurring in domestic situations in children, but also in adults. Lead poisoning was observed in a 65 years-old woman non-exposed to risk that caught our attention with a diagnostic suspicion of acute intermittent porphyria according to recurrent episodes of abdominal pain and neuropathy of upper limbs. Acute intermittent porphyria was excluded by a laboratory investigation that showed instead severe lead poisoning. After several thorough examinations of the domestic environment, the source of intoxication has been detected in some cooking pots that released high concentrations of lead. Ethylenediamine tetracetic acid disodium calcium therapy (three cycles) reduced consistently blood lead concentration and, after one year, neuropathy was almost entirely recovered

Clinical and molecular epidemiology of erythropoietic protoporphyria in Italy

Background: Erythropoietic protoporphyria (EPP) is a rare inherited disease associated with heme metabolism, characterized by severe life-long photosensitivity and liver involvement. Objectives: To provide epidemiological data of EPP in Italy. Materials and Methods: Prospective/retrospective data of EPP patients were collected by an Italian network of porphyria specialist centres (Gruppo Italiano Porfiria, GrIP) over a 20-year period (1996-2017). Results: In total, 179 patients (79 females) with a clinical and biochemical diagnosis of EPP were assessed, revealing a prevalence of 3.15 cases per million persons and an incidence of 0.13 cases per million persons/year. Incidence significantly increased after 2009 (due to the availability of alfa-melanotide, which effectively limits skin photosensitivity). Mean age at diagnosis was 28 years, with only 22 patients (12.2%) diagnosed 6410 years old. Gene mutations were assessed in 173 (96.6%) patients; most (164; 91.3%) were FECH mutations on one allele in association with the hypomorphic variant, c.315-48C, on the other (classic EPP), and nine (5.2%) were ALAS2 mutations (X-linked EPP). Only one case of autosomal recessive EPP was observed. Of the 42 different FECH mutations, 15 are novel, three mutations collectively accounted for 45.9% (75/164) of the mutations (c.215dupT [27.2%], c.901_902delTG [11.5%] and c.67\u2009+\u20095G\u2009&gt;\u2009A [7.2%]), and frameshift mutations were prevalent (33.3%). A form of light protection was used by 109/179 (60.8%) patients, and 100 (56%) had at least one \u3b1-melanotide implant. Three cases of severe acute liver involvement, requiring OLT, were observed. Conclusions: These data define, for the first time, the clinical and molecular epidemiology of EPP in Italy

Hepatitis B: prevention, protection, and occupational risk.

Since 1992, the inclusion of hepatitis B (HBV) vaccination has been recommended by the World Health Organization for all immunisation programmes implemented by nations. In Europe, the introduction of HBV vaccination has markedly reduced the incidence of acute HBV, and before the introduction of HBV vaccine, health care workers (HCW) were at considerable risk of infection. The present review discusses the main problems regarding three fundamental issues in hospital settings: 1) prevention of HBV in HCW, 2) protection induced by vaccination (problems regarding non-responders), and 3) risk for HCW exposed to blood-borne pathogens (occupational risk). The screening of HBV markers plays a decisive role in evaluating the degree of immune coverage in subjects exposed to biological risk and permits an increase immune coverage through of vaccine implementation

Modulation of the Mitochondrial Cyclosporin A-Sensitive Permeability Transition Pore by Matrix pH. Evidence that the Pore Open-Closed Probability is Regulated by Reversible Histidine Protonation

Energized mitochondria in sucrose medium take up a Ca2+ pulse but do not show opening of the permeability transition pore (MTP) upon membrane depolarization by uncoupler. This is due to locking of the pore in the closed conformation by matrix acidification and fast Ca2+ efflux following membrane depolarization (Petronilli, V., Cola, C., & Bernardi P. (1993) J. Biol. Chem. 268, 1011-1016). Here we show that addition of diethyl pyrocarbonate (DPC) prior to membrane depolarization restores the ability of uncoupler to induce MTP opening. Since DPC does not modify the rate and extent of matrix acidification and the rate and extent of Ca2+ release following addition of uncoupler, its effects on pore opening appear to be due to modification of histidyl residues regulating the pore open-closed probability. This hypothesis was confirmed in studies with deenergized mitochondria incubated in potassium thiocyanate medium. While at acidic pH values pore opening is otherwise prevented, DPC allows Ca2(+)-dependent pore opening at pH 6.5 in a process that maintains full sensitivity to cyclosporin A. Pore induction by DPC can be completely prevented and partially reversed by hydroxylamine, indicating that the effect of DPC can be specifically traced to carbethoxylation of histidyl residue(s) rather than to reaction with tyrosyl or sulfhydryl groups, while the possible involvement of lysyl residues cannot be excluded. Since DPC increases the pore open probability even at matrix pH values between 7.0 and 7.7, we propose that reversible protonation of one or more histidyl residues on the matrix side of the MTP plays a role in the physiological modulation of pore opening