[Radon risk evaluation in a hospital context]. / Valutazione del rischio da Radon in una realtà ospedaliera.

Italian legislation imposes radon concentration in occupational, underground premises as to not exceed the annual action level of 500 Bq/m3. A survey in a hospital of Milan founded concentrations never exceeding the action level, distribute around the median concentration of 16 Bq/m3, ranging between 6 e 214 Bq/m3 (Cmean = 38 +/- 50 Bq/m3). However, a pavilion, characterized by higher levels (C = 103 divided by 214 Bq/m3), was better studied by short-term monitoring, during summer and winter, confirming concentrations not exceeding legislative level, even if not negligible. Results underlines the importance of a monitoring strategy as punctual as possible. Moreover, shortterm measurements can represent a valid tool for premises screening in radon monitoring.

Bone marrow transplantation only partially restores purine metabolites to normal in adenosine deaminase-deficient patients.

To delineate the extent to which bone marrow transplantation provides "enzyme replacement therapy", we have determined metabolite concentrations in two patients with adenosine deaminase (ADA) deficiency treated with bone marrow transplants and rendered immunologically normal. 10 yr after engraftment of lymphoid cells, erythrocyte deoxy ATP was markedly decreased compared to the marked elevations of deoxy ATP observed in untreated patients, but was still significantly elevated (62 and 90 vs. normal of 6.0 +/- 6.0 nmol/ml packed erythrocytes). Similarly, deoxyadenosine and adenosine excretion were both markedly diminished compared to that of untreated patients but deoxyadenosine excretion was still clearly increased (20.1 and 38.6 vs. normal of less than 0.2 nmol/mg creatinine) while adenosine excretion was in the upper range of normal (7.0 and 8.1 vs. normal of 5.6 +/- 3.6 nmol/mg creatinine). Mononuclear cell deoxy ATP content was also elevated compared to normal (5.25 and 14.4 vs. 1.2 +/- 0.3). Separated mononuclear cells of bone marrow transplanted patients contain both donor lymphocytes and recipient monocytes. When mononuclear cells were depleted of the cells enriched for donor lymphocytes (i.e. monocyte depleted) was lower than that of the mixed mononuclear cells (2.2 vs. 5.26). Surprisingly, plasma adenosine was as high as in untreated ADA-deficient patients (3.2 and 1.5 vs. untreated of 0.3-3 microM). Consistent with the elevated plasma adenosine and urinary deoxyadenosine, erythrocyte S-adenosyl homocysteine hydrolase activity was diminished (0.88 and 1.02 vs. normal of 5.64 +/- 0.25). Thus, bone marrow transplantation of ADA-deficient patients not only provides lymphoid stem cells, but also partially, albeit incompletely, clears abnormally increased metabolites from nonlymphoid body compartments.

Genetic heterogeneity in partial adenosine deaminase deficiency.

Inherited deficiency of the enzyme adenosine deaminase (ADA) results in a syndrome of severe combined immunodeficiency (SCID). Children with ADA- -SCID lack ADA in all cells and tissues. In contrast, a "partial" deficiency of ADA has been described in six immunologically normal children from four different "families." These children lack ADA in their erythrocytes but retain variable amounts of activity in their lymphoid cells. We have examined ADA activity in lymphoid line cells from four of these children, who are unrelated, for evidence of genetic heterogeneity. One child, who is Caucasian, has an enzyme with increased electrophoretic mobility, a diminished isoelectric point (pI 4.8 vs. Nl = 4.9) and very low activity (2.3 vs. Nl = 82.9 +/- 12.9 nmol/mg protein per min); as a second child has an enzyme with normal electrophoretic mobility but increased isoelectric point (pI = 5.0), markedly diminished heat stability at 56 degrees C (t1/2 = 4.2' vs. Nl = 40') and low activity (12.1); a third has an enzyme with only diminished heat stability (t1/2 = 6.5'), no detectable abnormality in charge and almost normal activity (41.9); while the fourth exhibits only diminished ADA activity (25.0) with no striking qualitative abnormalities. Thus, we have found evidence for three different mutations at the structural locus for ADA in three of these individuals, (a) an acidic, low activity heat stable mutation (b) a basic, somewhat higher activity, heat labile mutation, and (c) a relatively normal activity heat labile mutation. In the fourth, there is as yet no compelling evidence for a mutation at the structural locus for ADA and a mutation at a regulatory locus cannot be excluded.

[Retrospective analysis of the accidents causing work inability in a teaching hospital during the time 2002-2006]. / Analisi retrospettiva degli eventi infortunistici causa di inabilità lavorativa relativi al quinquennio 2002-2006 in un'Azienda Aspedaliera Polo Universitario.

This study is a retrospective inquiry, based on the data of University Hospital "L. Sacco" in the period of five years 2002-2006. They were analyzed the relevant data to beyond 350 events cause of working inability.

[Hysteroscopy as a diagnostic method in postmenopausal metrorrhagia]. / L'isteroscopia come metodica diagnostica nelle metrorragie della post-menopausa.

We performed 215 hysteroscopies for post-menopausal bleeding. The most common abnormalities found were endometrial hypoatrophy and low-risk hyperplasia, the less common high-risk hyperplasia and adenocarcinoma of the endometrium. The correlation between hysteroscopic view and endometrial sampling was always very high. Hysteroscopy seems to be a very accurate method for evaluating patients with post-menopausal bleeding especially if associated with endometrial sampling.

Overproduction of DnaE protein (alpha subunit of DNA polymerase III) restores viability in a conditionally inviable Escherichia coli strain deficient in DNA polymerase I.

A polA12 recA718 double mutant of Escherichia coli, in which DNA polymerase I is temperature sensitive, was unable to maintain normal DNA synthesis or to form colonies on rich media at 42 degrees C. Overproduction of DnaE protein, the polymerizing alpha subunit of DNA polymerase III, restored bacterial DNA replication and cell viability, as well as the PolI-dependent replication of the plasmid carrying dnaE.

Constitutive expression of the SOS response in recA718 mutants of Escherichia coli requires amplification of RecA718 protein.

In recA718 lexA+ strains of Escherichia coli, induction of the SOS response requires DNA damage. This implies that RecA718 protein, like RecA+ protein, must be converted, by a process initiated by the damage, to an activated form (RecA) to promote cleavage of LexA, the cellular repressor of SOS genes. However, when LexA repressor activity was abolished by a lexA-defective mutation [lexA(Def)], strains carrying the recA718 gene (but not recA+) showed strong SOS mutator activity and were able to undergo stable DNA replication in the absence of DNA damage (two SOS functions known to require RecA activity even when cleavage of LexA is not necessary). lambda lysogens of recA718 lexA(Def) strains exhibited mass induction of prophage, indicative of constitutive ability to cleave lambda repressor. When the cloned recA718 allele was present in a lexA+ strain on a plasmid, SOS mutator activity and beta-galactosidase synthesis under LexA control were expressed in proportion to the plasmid copy number. We conclude that RecA718 is capable of becoming activated without DNA damage for cleavage of LexA and lambda repressor, but only if it is amplified above its base-line level in lexA+ strains. At amplified levels, RecA718 was also constitutively activated for its roles in SOS mutagenesis and stable DNA replication. The nucleotide sequence of recA718 reveals two base substitutions relative to the recA+ sequence. We propose that the first allows the protein to become activated constitutively, whereas the second partially suppresses this capability.

RecA protein of Escherichia coli has a third essential role in SOS mutator activity.

The DNA damage-inducible SOS response of Escherichia coli includes an error-prone translesion DNA replication activity responsible for SOS mutagenesis. In certain recA mutant strains, in which the SOS response is expressed constitutively, SOS mutagenesis is manifested as a mutator activity. Like UV mutagenesis, SOS mutator activity requires the products of the umuDC operon and depends on RecA protein for at least two essential activities: facilitating cleavage of LexA repressor to derepress SOS genes and processing UmuD protein to produce a fragment (UmuD') that is active in mutagenesis. To determine whether RecA has an additional role in SOS mutator activity, spontaneous mutability (tryptophan dependence to independence) was measured in a family of nine lexA-defective strains, each having a different recA allele, transformed or not with a plasmid that overproduces either UmuD' alone or both UmuD' and UmuC. The magnitude of SOS mutator activity in these strains, which require neither of the two known roles of RecA protein, was strongly dependent on the particular recA allele that was present. We conclude that UmuD'C does not determine the mutation rate independently of RecA and that RecA has a third essential role in SOS mutator activity.

Recovery from ultraviolet light-induced inhibition of DNA synthesis requires umuDC gene products in recA718 mutant strains but not in recA+ strains of Escherichia coli.

Ultraviolet light (UV) inhibits DNA replication in Eschericia coli and induces the SOS response, a set of survival-enhancing phenotypes due to derepression of DNA damage-inducible genes, including recA and umuDC. Recovery of DNA synthesis after UV irradiation ("induced replisome reactivation," or IRR) is an SOS function requiring RecA protein and postirradiation synthesis of additional protein(s), but this recovery does not require UmuDC protein [Khidhir, M. A., Casaregola, S. & Holland, I. B. (1985) Mol. Gen. Genet. 199, 133-140]. IRR occurs in strains carrying either recA718 (which does not reduce recombination, SOS inducibility, or UV mutagenesis) or umuC36 (which eliminates UV mutability), but not in recA718 umuC36 double mutants. In recA430 mutant strains, IRR does not occur whether or not functional UmuDC protein is present. IRR occurs in lexA-(Ind-) (SOS noninducible) strains if they carry an operator-constitutive recA allele and are allowed to synthesize proteins after irradiation. We conclude the following: (i) that UmuDC protein corrects or complements a defect in the ability of RecA718 protein (but not of RecA430 protein) to promote IRR and (ii) that in lexA(Ind-) mutant strains, IRR requires amplification of RecA+ protein (but not of any other LexA-repressed protein) plus post-UV synthesis of at least one other protein not controlled by LexA protein. We discuss the results in relation to the essential, but unidentified, roles of RecA and UmuDC proteins in UV mutagenesis.

An SOS-inducible defective retronphage (phi R86) in Escherichia coli strain B.

In Escherichia coli, RecA protein regulates the DNA damage-inducible survival-enhancing SOS response. Mutant allele recA730, which causes constitutive SOS expression, is lethal at high temperatures in B/r, a derivative of wild-type B, but not in K-12 or in certain B/r--K-12 hybrids. We present evidence that killing is due to SOS induction of a defective retronphage, phi R86, which is integrated into the B/r chromosome at 19 min, but is absent in K-12. phi R86 contains retron EC-86 which encodes reverse transcriptase and a small multicopy DNA-RNA complex, msDNA-RNA. Induction of phi R86 in recA730 B/r strains results in inhibition of host DNA replication before cell death. A retronphage 'killer' gene, ORF336, when overexpressed from a plasmid, causes similar effects without SOS induction. phi R86 is not detectably u.v.-inducible in recA+ strains.

Increased excretion of modified adenine nucleosides by children with adenosine deaminase deficiency.

We have identified seven adenine nucleosides in urines of untreated adenosine deaminase (ADA) deficient patients, four of which (adenosine, 2'-deoxyadenosine, 1-methyladenosine and N6-methyladenosine) have been previously identified in urines of normals and/or ADA deficient patients. We confirm that ADA deficient patients excrete markedly increased amounts of 2'-deoxyadenosine (582 +/- 363 versus normal of less than 0.1 nmoles/mg creatinine) and increased amounts of adenosine (29.4 +/- 5.7 versus normal of 4.12 +/- 1.0 nmoles/mg creatinine). We have found three modified adenine nucleosides previously undetected in human urine. These three compounds are 2'-O-methyladenosine, N6, 2'-O-dimethyladenosine and an as yet incompletely characterized modified adenine nucleoside, R-adenosine. Only ADA deficient patients excrete detectable amounts of 2'-O-methyladenosine (2.1 +/- 1.1 versus normal of less than 0.1 nmoles/ mg creatinine), whereas both normals and ADA deficient children excrete N6, 2'-O-dimethyladenosine and R-adenosine. However, ADA deficient patients do excrete increased amounts of R-adenosine (5.5 +/- 1.0 versus normal of 1.4 +/- 0.4 nmoles/mg creatinine).