Calmodulin-dependent cyclic nucleotide phosphodiesterase in adult and developing chick spinal cord

We investigated the level and characteristics of "low Km" 3'-5' cyclic nucleotide phosphodiesterase (PDE) activity in adult and embryo chick spinal cord. The DEAE cellulose chromatography elution profile of Triton X-100 extracts showed a single peak of calmodulin-dependent cAMP/cGMP PDE activity. After two additional purification steps, this activity showed a five-fold activation by calmodulin (Ka = 1.5 nM) for cGMP hydrolysis, and a linear kinetic behaviour with a Km of 1.3 microM. Conversely, the activity showed a biphasic behaviour for cAMP hydrolysis, with Km values of 3.1 and 18.5 microM. The enzyme showed a Stokes radius of 4.5 nm. Western blot analysis of the purified enzyme revealed two immunoreactive bands with molecular mass of 59 and 65 kDa, respectively. Immunohistochemical staining showed motoneuron decoration both on cell soma and fibres. The developmental pattern of Ca2+-calmodulin-dependent PDE expression in spinal cord was also studied; the hydrolytic activity for both substrates has been found to increase constantly from E5 to post-hatching stages, when it appears 5.6-fold higher as compared to the early embryo levels. Furthermore, in cultured spinal cord neurons from E8 embryos, muscle extract has been shown to induce a two-fold increase of Ca2+-calmodulin-dependent cGMP activity. In conclusion, the studies reported here present three relevant findings: (1) the presence in adult and embryo chick spinal cord of PDE activities with characteristics similar to those of the mammalian PDE I enzyme; (2) its localization in the ventral horn motoneurons; (3) its regulated expression during embryogenesis that is possibly related to soluble epigenetic factors produced by the target cells.

Differences in hepatitis C virus quasispecies composition between liver, peripheral blood mononuclear cells and plasma

Hepatitis C virus (HCV) exists in vivo as a highly variable mixture of closely related genomes (quasispecies), but the pathogenetic significance of such heterogeneity is still largely unknown. To investigate this issue, we compared the composition of HCV quasispecies found in the liver, peripheral blood mononuclear cells (PBMC) and plasma of ten patients by single-strand conformation polymorphism analysis of the E2/NS1 region and sequencing of the variants detected. We found considerable quasispecies differences between the liver and PBMC in all the patients, involving variant numbers, relative quantities and relative electrophoretic mobilities, but no apparent tissue-specific trend. Genome variants present in the liver and/or PBMC were not detected in the corresponding plasma samples, while certain HCV variants were present only in plasma. No dominant amino acids or amino acid pattern characteristic of variants present solely in the PBMC were detected in the E2/NS1 region sequenced.

Comparative evaluation of five rapid methods for identifying subtype 1b and 2c hepatitis C virus isolates

A panel of 61 HCV isolates belonging to five different subtypes were used to evaluate five methods for rapid typing of HCV RNA: an in-house type-specific polymerase chain reaction based on the core region (type-specific PCR), a commercial amplification of the core region followed by hybridisation to probe coated wells (DEIA), a commercial amplification of the 5'-UTR region followed by hybridisation to probes immobilised on strips (LiPA), an in-house restriction fragment polymorphism analysis of the 5'UTR (RFLP), and a commercial serological method using synthetic peptides from the NS4 region (serotyping). The correct viral type was identified in 90% of cases by DEIA, in 82% of cases by type-specific PCR, in 80% of cases by LiPA and RFLP, and in 67% of cases by serotyping. Correct identification of the virus subtype was much less frequent and was beyond the performance characteristics of some assays. Major problems were found in the identification of isolates belonging to type 2. This was probably at least partly due to the fact that all type 2 isolates in the viral panel were of subtype 2c, which has been considered rare until recently.

Induction of cyclic AMP and cyclic GMP 3':5'-cyclic nucleotide phosphodiesterase activities in neuroblastoma lines under differentiating conditions

It is now widely accepted that cyclic nucleotide phosphodiesterases (PDEs) play fundamental roles in signal transduction pathways; they show a remarkable molecular complexity, different tissue distribution and complex regulatory mechanisms. Here we report PDE isoforms expression in two dibutyryl cyclic AMP differentiated murine cell lines: the hybrid neuroblastoma-glioma 108CC15 and the parental neuroblastoma N18TG2. They differ in the ability to establish functional synapses, a feature present only in the former. Ionic exchange chromatography elution profiles of N18TG2 and 108CC15 undifferentiated cell extracts show two main peaks of activity. The first one hydrolyzes cyclic GMP and is specifically inhibited by Zaprinast, thus representing a member of the PDE5 family. The second peak hydrolyzes cyclic AMP and is significantly inhibited by rolipram, as all the PDE4 family members. The induction of differentiation by dibutyryl cyclic AMP in both clonal lines results in an increase of PDE activities only after 3 hr of treatment, suggesting that protein neosynthesis is involved. Interestingly in both clones, besides the increase in cyclic AMP hydrolyzing specific activity (3.1-fold in 108CC15 and 2.5-fold in N18TG2), we also observed an increase in cyclic GMP hydrolyzing activity (1.7-fold in 108CC15 and 4.3-fold in N18TG2). While the induction of PDE4, previously reported also in other cellular systems, could be considered as a feedback response to the higher cyclic AMP levels, this is not true for the isoform that hydrolyzes cyclic GMP. These data suggest that the induction of PDE isoforms in neuroblastoma cells could be related to the activation of neuronal differentiative pathway.

Subtype 2c of hepatitis C virus is highly prevalent in Italy and is heterogeneous in the NS5A region

Hepatitis C virus (HCV) isolates, obtained from 50 Italian patients with community-acquired infection, that had previously been classified as subtype 2a or 2b by current rapid genotyping methods were further characterized by partial sequence analysis. All the isolates were reclassified: 45 within subtype 2c and the other 5 as subtype 1b, 3a, or 4d. Thus, subtype 2c is much more prevalent than previously recognized, with about 30% of all HCV strains detected in Italy being subtype 2c. In contrast, isolates of subtypes 2a and 2b appear to be infrequent, if not absent. Further studies showed that subtype 2c isolates are heterogeneous in the NS5A region, in that they may or may not contain a 57-nucleotide (nt) segment spanning from nt 7533 to nt 7589 of the viral genome. Partial nucleotide sequencing of the NS5B region of four 2c subtypes excluded the possibility that the isolates possessing or not possessing the 57-nt segment in the NS5A region may have resulted from recombination phenomena.

Phosphodiesterase specific inhibitors control cell growth of a human neuroepithelioma cell line

The effects of cyclic nucleotide phosphodiesterase (PDE) inhibitors on cell proliferation of SK-N-MC human neuroepithelioma cell line was studied. Clonal density experiments in the presence of 100 microM rolipram and zaprinast showed respectively 27% and 91% inhibition. The effects of PDE inhibitors were then investigated on crude cell extracts; the calculated IC50 were 32 microM for zaprinast and 16 nM for DC-TA-46; the latter inhibitor was used instead of rolipram for its higher efficacy. Dose-response experiments in clonal density conditions showed IC50 of 5 microM and 1.8 microM in the presence respectively of zaprinast and rolipram. These data show that both inhibitors are effective in reducing cell growth, although the response was quantitatively different.

X-FINE--a refinement program for FEFF input parameters

X-FINE is an interactive and user-friendly tool to optimize input parameters (S20, sigma2, DeltaE) of the FEFF program, a package for EXAFS analysis.

A functional role for some Fugu introns larger than the typical short ones: the example of the gene coding for ribosomal protein S7 and snoRNA U17

The compact genome of Fugu rubripes, with its very small introns, appears to be particularly suitable to study intron-encoded functions. We have analyzed the Fugu gene for ribosomal protein S7 (formerly S8, see Note), whose Xenopus homolog contains in its introns the coding sequences for the small nucleolar RNA U17. Except for intron length, the organization of the Fugu S7 gene is very similar to that of the Xenopus counterpart. The total length of the Fugu S7 gene is 3930 bp, compared with 12691 bp for Xenopus. This length difference is uniquely due to smaller introns. Although short, the six introns are longer than the approximately 100 bp size of most Fugu introns, as they host U17 RNA coding sequences. While four of the six U17 sequences are 'canonical', the remaining two represent diverged U17 pseudocopies. In fact, microinjection in Xenopus oocytes of in vitro synthesized Fugu transcripts containing the 'canonical' U17f sequence results in efficient production of mature U17 RNA, while injection of a transcript containing the U17 psi b sequence does not.

Unique features in the mitochondrial D-loop region of the European seabass Dicentrarchus labrax

We have cloned and sequenced the displacement-loop (D-loop) region of the mitochondrial DNA (mtDNA) from the European seabass Dicentrarchus labrax (Dl). This sequencing revealed the presence of four tandemly repeated elements (R1, R2, R3 and R4); the individual variation in mtDNA total length is entirely accounted for by their variable number. The individuals examined also possessed an imperfect copy of one of the tandem repeats (psi R2). At least one termination-associated sequence (TAS) is present in each of the repeats and in two copies 5' upstream from the tandem array as well. The alignment of the Dl D-loop region with D-loop sequences from four other Teleosts and one Chondrosteus showed the Dl sequence to be larger than that of other fish. The extraordinary length of the Dl D-loop sequence is also due to the 5' and 3' regions that are flanking the tandem array, the largest ones to date analyzed in fish. In this study, we also report the unique organization and localization of putative TAS and conserved-sequence block (CSB) elements, and the presence of a conserved 218-bp sequence in the Dl D-loop region.

Effects of Di-(2-ethylhexyl)phthalate on peroxisomes of liver, kidney and brain of lactating rats and their pups

Di-(2-ethylhexyl)phthalate administered to adult lactating rats, from delivery to weaning, induces modifications of the peroxisomal enzymatic pattern in the liver, kidney and brain of both dams and pups. These modifications are age- and organ-dependent. Biochemical analysis shows that: 1) catalase specific activity is two-fold increased in the liver of both adult and newborn animals, in the kidney of newborns and in the brain of adults. 2)D-amino acid oxidase doubles in all newborn organs and in adult brain; it increases, although to a lesser extent, also in adult kidney, while it is half-reduced in adult liver. 3) Dihydroxyacetone phosphate acyl transferase only doubles in newborn liver, remaining fairly unchanged in all the other tested tissues. 4) Palmitoyl-CoA oxidase is greatly induced in the liver of both dams and litters, doubled in the kidneys and slightly increased or not at all in the brain of pups and mothers, respectively. The effect of the drug on enzyme activities is reversible, with different time courses depending on the considered enzyme and organ. Western blottings confirm the biochemical data. Electron microscopy shows proliferated peroxisomes in the liver and kidney of treated animals but not in the brain, where high catalase-like immunoreactivity is observed in the cytosol of neurons. Taken together, our data demonstrate that the response of peroxisomal enzymes to DEHP treatment is age- as well as tissue-dependent and specific for each enzyme studied.

Activities of 3':5' cyclic nucleotide phosphodiesterases in the superior cervical ganglion of rat: characterization, compartmentalization and observations in young and old animals

We investigated the presence and features of "low Km" 3'-5' cyclic nucleotide phosphodiesterase activity in the homogenates and extracts of rat superior cervical ganglion. The DEAE chromatographic elution profile of a Triton X-100 extract showed two peaks of cAMP phosphodiesterase activity eluted at 280 and 600 mM sodium acetate and two peaks of cGMP phosphodiesterase activity eluted at 300 and at 500 mM sodium acetate. The activity was poorly stimulated by calcium-calmodulin and neither stimulated or inhibited by cGMP. Both cGMP PDE peaks were inhibited by zaprinast, with IC50's of 1.4 microM and 0.28 microM: their Km values were 4.4 and 3.8 microM, respectively. These features, together with cGMP binding activity, indicate that both enzymes belong to the phosphodiesterase V family. The Km values of the first and second cAMP phosphodiesterase peaks were 1.7 and 3.8 microM. Although both peaks displayed a cAMP specific hydrolysis, only the second peak was inhibited by RO 20-1724, with an IC50 of 8 microM. Preganglionic denervation indicated that the bulk of phosphodiesterase activity is localized in ganglion cells. In order to investigate possible effects of aging on the ganglionic function, phosphodiesterase activity was assayed in the ganglia of young (3 months) and old (25 months) male Fisher rats. The chromatographic profiles and kinetic features revealed no significant differences between young and old rats.

Differential decrease of copper content and of copper binding to superoxide dismutase in liver, heart and brain of copper-deficient rats

Dietary copper-deficiency in rats produced a organ-specific decrease of copper content. This was paralleled by a decrease of the activity of the copper-enzyme superoxide dismutase. In liver such a decrease is partially due to the existence of an apo-form of superoxide dismutase, which can be reactivated by addition of exogenous copper to tissue extracts. These results demonstrate in vivo that superoxide dismutase is post-translationally modulated by copper in higher vertebrates as previously found for yeast and mammalian cells in culture.

Cloning and characterization of the European seabass, Dicentrarchus labrax, mitochondrial genome

Mitochondrial DNA (mtDNA) from the European seabass, Dicentrarchus labrax, has been cloned and characterized. Its gene organization was deduced by a comparison of the sequenced termini of different subclones obtained from European seabass mtDNA to the completely-sequenced mtDNAs from carp and freshwater loach. The difference in genome size between the European seabass mtDNA (approximately 18 kb) and most of the other characterized fish mtDNAs (approximately 16.5 kb) is accounted for by the displacement-loop (D-loop). Comparisons have been performed between the derived amino-acid sequences of three sequenced genes, cytochrome c oxidase subunit 2 (COII), NADH dehydrogenase subunit 4L (ND4L) and ATP synthase subunit 8 (ATPase8), from D. labrax, and their counterparts in other fishes and Xenopus laevis.

Competitive polymerase chain reaction for quantitating feline immunodeficiency virus load in infected cat tissues

To quantitate FIV provirus copy numbers present in tissue of infected cats, we have applied a competitive polymerase chain reaction (cPCR) recently described for HIV. The method consists in coamplifying a fixed amount of the DNA to be examined with graded copy numbers of a DNA competitor incorporating a short deletion and bearing the same primer recognition sequences. These conditions ensure almost identical thermodynamic and amplification efficiency for both template species but permit a prompt recognition of the two amplification products by gel electrophoresis. Since the amounts of the two amplicons are dependent on relative initial template concentrations, the number of FIV genomes in the sample can be calculated by densitometric analysis of the electrophoretic bands. After validation, the method has been applied to study the provirus loads in the tissues of cats infected with the Pisa-M2 isolate of FIV.

A preparative method for isolation of peroxisomes from rat kidney

A new method for the isolation of peroxisomes from rat kidney cortex is described. The L fraction obtained according to Wattiaux-De Coninck et al. (1965) was layered on a discontinuous Nycodenz gradient (density = 1.15-1.21 g/ml) and then centrifuged in a fixed angle rotor for 45 min. at 136,000 g. On the basis of the morphological and biochemical analysis, the fraction recovered at the bottom of the tube was composed mainly by peroxisomes enriched in fatty acyl beta-oxidation system, whereas lower enrichment was found for other peroxisomal marker enzymes. Negligible contamination by mitochondria (marker enzyme cytochrome oxidase), lysosomes (marker enzyme acid phosphatase) and microsomes (marker enzyme NADPH cytochrome c reductase) was found.

Purification of peroxisomal fraction from rat brain

A purification procedure to obtain peroxisomes (microperoxisomes) from the brain of suckling rats is reported. A P2 fraction, (crude light mitochondria) frozen and thawed seven times, was subfractionated yielding a P4 fraction, 4-fold enriched in catalase activity with respect to the cytoplasmic extract S1. The P4 fraction was used for further purification of peroxisomes by isopicnic centrifugation on Nycodenz gradient (1.10-1.20 g/ml). When the cerebellum was not included in the starting material, the equilibrium density of peroxisomes was 1.152-1.162 g/ml. In this case the overall yield of catalase in the most enriched fraction was 7% and its relative specific activity more than 50. When the cerebellum was included in the total homogenate, the equilibrium density shifted towards higher values (1.177 g/ml) and in this case the catalase relative specific activity in the peroxisomal enriched fraction was extremely high (> 100). The biochemical results, together with the electron microscope examination of the purified fractions, demonstrate that our procedure allows the best purification of brain peroxisomes so far obtained. The different equilibrium densities of peroxisomes observed in the two sets of experiments are interpreted in terms of size heterogeneity of these organelles in different brain portions and cell types.

Characterization of 3':5' cyclic nucleotide phosphodiesterase activities of mouse neuroblastoma N18TG2 cells

Characterization of 'low Km' 3':5' cyclic nucleotide phosphodiesterase activities (PDE) expressed in mouse N18TG2 neuroblastoma cells is reported. At least 3 peaks of activity were isolated by DEAE chromatography, none of which was calcium-calmodulin stimulated and cGMP stimulated or inhibited. A first peak elutes at 200 mM sodium acetate; it specifically hydrolyzes cGMP with a Km of 4.7 microM and shows sensitivity to zaprinast [M&B 22948] (1.8 microM). A second peak eluting at 410 mM sodium acetate hydrolyzes both cyclic nucleotides. A third peak, specific for cAMP hydrolysis, elutes at 580 mM sodium acetate, has a Km of 3.2 microM and is sensitive to RO 20 1724 (7.6 microM) and rolipram (2 microM). Hydrodynamic analysis showed for the first peak a Stokes radius of 5.3 nm with a sedimentation coefficient of 8.1 S, a frictional ratio (f/fo) of 1.41 and a native molecular mass of 182 kDa. The same analysis for peak 3 showed a Stokes radius of 4.1 nm with a sedimentation coefficient of 3.2 S, a frictional ratio of 1.63 and a native molecular mass of 56 kDa. The biochemical features reported for the enzyme eluting in the first peak, and its cGMP-binding activity stimulated by inhibitors of phosphodiesterase activity, demonstrate that it belongs to the PDE V subfamily; on the other hand the cAMP specific enzyme eluting in the third peak can be assigned to the 'RO 20 1724 inhibited' form. The significance of these findings is discussed in relation to the functional characteristics of the N18TG2 cell line.

Purification and characterization of a low-Km 3':5'-cyclic adenosine phosphodiesterase from post-meiotic male mouse germ cells

We describe the purification and the study of the kinetic and hydrodynamic properties of a 'low Km' cAMP phosphodiesterase specifically expressed in haploid male germ cells of the mouse. The enzyme has been purified approx. 13,000-fold with respect to the activity in total cell homogenate. The purified enzyme hydrolyzed specifically cAMP with a Km of 3.3 microM and with a Vmax of 10.5 mumol of cAMP hydrolyzed/min per mg of protein. The hydrolytic activity was neither stimulated nor inhibited by cGMP, whereas it was inhibited by RO 20-1724 and Rolipram. The enzyme showed a Stokes radius of 3.8 nm and a sedimentation coefficient of 3.1 S, corresponding to a native molecular mass of 50 kDa and a frictional ratio of 1.53. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis of sucrose gradient fractions of the purified enzyme showed a major band of 43 kDa copeaking with enzyme activity.

A new continuous optical assay for maltase and sucrase

A new method for the assay of maltase and sucrase is reported. The method makes use of mutarotase, hexokinase and glucose 6-phosphate dehydrogenase as ancillary enzymes. The reaction is linear at least up to a delta E/min of 0.13.

Expression of the c-kit proto-oncogene in the murine male germ cells

The proto-oncogene c-kit encodes a transmembrane protein tyrosine kinase receptor. The c-kit gene has recently been shown to be allelic with the W locus. Mutations at the white spotting locus (W) affect various aspects of hematopoiesis, melanogenesis and gametogenesis during development and in the adult animal. We have investigated the expression of the proto-oncogene c-kit in mouse testicular cell populations. The c-kit mRNA was found to be expressed at high levels in spermatogonia, and at lower levels in meiotic pachytene spermatocytes. Moreover, two novel testis-specific c-kit transcripts of 3.5 and 2.3 kb are present in postmeiotic haploid germ cells. These results suggest a role of c-kit not only during testis development in the embryo, but also throughout all stages of male germ cell development after birth.

HIV serology among Italian male military recruits at entrance and discharge

To evaluate the usefulness of anti-HIV mass screenings, we examined 662 new military recruits and 1353 soldiers being discharged. None of the former and only one of the latter (0.07%) resulted seropositive on repeated ELISA and Western-blot. For comparison we also report the results of routine anti-HIV antibody testing in our diagnostic laboratory: the highest proportion of seropositive subjects was found among symptomatic patients (79%), followed by haemophiliac patients (31%), drug addicts (24%), sexual partners of seropositive subjects (21%), prisoners (5%) and homosexual men (5%). Health care personnel and prison guards were all negative. These data confirm that in Italy HIV infection is still relatively confined to the classic risk groups. While generalized screening during military service seems to be excessive, periodic sample surveys could be very useful to follow the evolution of HIV epidemiology.

Endothelial cell motility, integrin receptor clustering, and microfilament organization are inhibited by agents that increase intracellular cAMP

Adhesion of human umbilical vein endothelial cells (ECs) to various extracellular matrix proteins is mostly mediated by receptors of the integrin family. The interaction of ECs with extracellular matrix proteins is accompanied by cell spreading, cytoskeletal organization, and clustering of the specific integrin receptors in complex supramolecular structures known as adhesion plaques or focal contacts. Little is known on the functional role of focal contacts in EC adhesion and motility and on the possibility to modulate their organization. In this article we report that an increase in intracellular cAMP levels severely impaired focal contact formation. This process did not affect cell attachment, but increased cell adhesion and strongly inhibited cell motility. ECs were treated with the cAMP-increasing agents forskolin and 2-chloro-adenosine or with the cAMP analogue 8-bromo-cAMP. When treated cells were seeded on purified vitronectin, fibrinogen, or fibronectin little modification in the number of attached cell was observed. In contrast ECs showed impaired organization of microfilaments and poorly developed clusters of beta 3- and beta 1-integrin receptors. On a vitronectin substrate, vinculin followed the distribution of beta 3-receptors. It was typically enriched at the focal contacts in control cells but was fragmented in small dots at the cell periphery in treated cells, as were bundles of actin stress fibers. Similarly, when forskolin was added to ECs spread on vitronectin or on fibrinogen, there was a progressive but reversible disruption of actin microfilaments and diffusion of beta 3 receptors. This was accompanied by a tighter adhesion of the cells to substrata. Migration of ECs in response to different matrix proteins was severely inhibited by cAMP-increasing agents. These data indicate that EC adhesion can occur very efficiently in the absence of fully developed beta 3- or beta 1-integrin receptor-containing focal contacts but suggest that the capacity to normally assemble focal contacts and cytoskeletal proteins is required for full cell spreading and migration.

[Brodie's syndrome]

The authors, after having completed a wide bibliographic research on this subject, examine the etiopathogenesis of Brodie's syndrome, and distinguish a congenital from an acquired form. The different therapeutic possibilities, orthodontic or surgical, have been examined and discussed.

Fibrinogen induces endothelial cell adhesion and spreading via the release of endogenous matrix proteins and the recruitment of more than one integrin receptor

We have previously shown that fibrinogen (fg) acts as a subendothelial matrix protein in promoting human endothelial cell (EC) adhesion and cytoskeletal organization. In this study we report that EC spreading on fg, at variance with other matrix proteins, requires endogenous matrix protein synthesis and secretion. ECs, upon seeding on fg, promptly released and organized a fibronectin (fn) matrix. Fg was more effective than vitronectin (vn) in promoting the deposition of this protein. ECs treated with monensin to block matrix protein secretion still adhered to fg but did not properly organize their cytoskeleton and adhesion structures. In contrast, monensin did not affect EC spreading either on vn or on fn. Using antibodies to the alpha and beta chains of fn (alpha 5 beta 1) and vn (alpha v beta 3) receptors, it was found that ECs adherent to fg show clustering and organization in adhesion structures of both type of receptors. A faint staining of adhesion structures with alpha 2 but not alpha 3 and alpha 6 antibodies was also observed. Antibodies either to vn or fn receptors were able to disrupt the EC monolayer and to induce EC retraction and detachment, thus indicating that both receptors are important in maintaining a sustained EC adhesion to fg. However, when ECs were treated with monensin only the vn receptor was organized in adhesion structures while the fn receptor was diffusely distributed. This suggests that clustering of the fn receptor is mediated by the release of endogenous matrix proteins induced by the exposure to fg. In conclusion, fg has a peculiar and complex type of interaction with ECs since it requires endogenous matrix protein release and the recruitment of more than one adhesive receptor. This suggests a specific way of response of ECs to each extracellular matrix component.

Stress at work and mental health status among female hospital workers

Relations between working conditions and mental health status of female hospital workers were studied in a sample of 1505 women: 43% were nurses, 32% auxiliaries, and 7% ancillary staff; 13% were other qualified health care staff, mainly head nurses; 5% had occupations other than direct health care; 63% worked on the morning, 20% on the afternoon, and 17% on the night shift. Data were collected at the annual routine medical visit by the occupational health practitioner, using self administered questionnaires and clinical assessments. Five health indicators were considered: a high score to the general health questionnaire (GHQ); fatigue; sleep impairment; use of antidepressants, sleeping pills, or sedatives; and diagnosis of psychiatric morbidity at clinical assessment. Four indices of stress at work were defined: job stress, mental load, insufficiency in internal training and discussion, and strain caused by schedule. The analysis was conducted by multiple logistic regression, controlling for type of occupation, shift, number of years of work in hospital, daily travel time to work, age, marital status, number of children, and wish to move house. Sleep impairment was mostly linked to shift and strain due to schedule. For all other indicators of mental health impairment and especially high GHQ scores, the adjusted odds ratios increased significantly with the levels of job stress, mental load, and strain due to schedule. This evidence of association between work involving an excessive cumulation of stress factors and mental wellbeing should be considered in interventions aimed at improving the working conditions of hospital workers.

Von Willebrand factor promotes endothelial cell adhesion via an Arg-Gly-Asp-dependent mechanism

Von Willebrand factor (vWF) is a constitutive and specific component of endothelial cell (EC) matrix. In this paper we show that, in vitro, vWF can induce EC adhesion and promote organization of microfilaments and adhesion plaques. In contrast, human vascular smooth muscle cells and MG63 osteosarcoma cells did not adhere and spread on vWF. Using antibodies to the beta chains of fibronectin (beta 1) and vitronectin (beta 3) receptors it was found that ECs adherent to vWF show clustering of both receptors. The beta 1 receptor antibodies are arranged along stress fibers at sites of extracellular matrix contact while the beta 3 receptor antibodies were sharply confined at adhesion plaques. ECs release and organize endogenous fibronectin early during adhesion to vWF. Upon blocking protein synthesis and secretion, ECs can equally adhere and spread on vWF but, while the beta 3 receptors are regularly organized, the beta 1 receptors remain diffuse. This suggests that the organization of the beta 1 receptors depend on the release of fibronectin and/or other matrix proteins operated by the same cell. Antibodies to the beta 3 receptors fully block EC adhesion to vWF and detach ECs seeded on this substratum. In contrast, antibodies to the beta 1 receptors are poorly active. Overall these results fit with an accessory role of beta 1 receptors and indicate a leading role for the beta 3 receptors in EC interaction with vWF. To identify the EC binding domain on vWF we used monoclonal antibodies produced against a peptide representing the residues Glu1737-Ser1750 of the mature vWF and thought to be important in mediating its binding to the platelet receptor glycoprotein IIb-IIIa. We found that the antibody that recognizes the residues 1,744-1,746, containing the Arg-Gly-Asp sequence, completely inhibit EC adhesion to vWF whereas a second antibody recognizing the adjacent residues 1,740-1,742 (Arg-Gly-Asp-free) is inactive. Both antibodies do not interfere with EC adhesion to vitronectin. This defines the molecular domain on vWF that is specifically recognized by ECs and reaffirms the direct role of the Arg-Gly-Asp sequence as the integrin receptor recognition site also in the vWF molecule.

Testis-specific calmodulin-dependent phosphodiesterase. A distinct high affinity cAMP isoenzyme immunologically related to brain calmodulin-dependent cGMP phosphodiesterase

A cell-specific isozyme of calmodulin (CaM)-dependent phosphodiesterase that exhibits micromolar affinity for cAMP has been purified 900-fold from mouse testis by DEAE chromatography, gel filtration, affinity chromatography with CaM-Sepharose 4B, and isoelectric focusing. The highly purified enzyme is stimulated 5-6-fold by CaM in the presence of Ca2+ and hydrolyzes both cAMP and cGMP with anomalous substrate dependence, i.e. high and low affinity components (Km 2 and 20 microM) are observed either in the presence or absence of CaM. Each of the substrates acts as a noncompetitive inhibitor of the other, suggesting the presence of two distinct catalytic sites on the enzyme. Hydrodynamic studies suggest that the testis phosphodiesterase is an asymmetric monomer of 68-70 kDa that forms a dimer after interaction with Ca2+ and CaM; the tetrameric complex exhibits an apparent molecular size of 180 kDa. These enzymatic and biophysical properties differ in many respects from those of the brain isozyme, suggesting that they are different proteins. Nevertheless, common epitopes do exist, since the testis enzyme interacted with rabbit antibodies raised against bovine brain CaM-dependent phosphodiesterase. The major peptide of 68 kDa was strongly reactive on immunoblots, and was distinguished unambiguously from the 60-kDa species from mouse brain. A comparison of the immunoreactive fragments produced by limited proteolysis with staphylococcal V-8 protease indicated several similarities in the domains of these polypeptides. Thus, although differing in several important physical and biochemical parameters, the testis enzyme appears immunologically related to CaM-dependent phosphodiesterase from brain. On the basis of these data, we conclude that common elements of the structural genes for these isozymes have been conserved, whereas certain biological properties, including substrate specificity, have diverged substantially.

Phosphorylation of ankyrin down-regulates its cooperative interaction with spectrin and protein 3

Ankyrin mediates the primary attachment between beta spectrin and protein 3. Ankyrin and spectrin interact in a positively cooperative fashion such that ankyrin binding increases the extent of spectrin tetramer and oligomer formation (Giorgi and Morrow: submitted, 1988). This cooperative interaction is enhanced by the cytoplasmic domain of protein 3, which is prepared as a 45-41-kDa fragment generated by chymotryptic digestion of erythrocyte membranes. Using sensitive isotope-ratio methods and nondenaturing PAGE, we now demonstrate directly (1) the enhanced affinity of ankyrin for spectrin oligomers compared to spectrin dimers; (2) a selective stimulation of the affinity of ankyrin for spectrin oligomer by the 43-kDa cytoplasmic domain of protein 3; and (3) a selective reduction in the affinity of ankyrin for spectrin tetramer and oligomer after its phosphorylation by the erythrocyte cAMP-independent membrane kinase. The phosphorylation of ankyrin does not affect its binding to spectrin dimer. Ankyrin also enhances the rate of interconversion between dimer-tetramer-oligomer by 2-3-fold at 30 degrees C, and in the presence of the 43-kDa fragment, ankyrin stimulates the rate of oligomer interconversions by nearly 40-fold at this temperature. These results demonstrate a long-range cooperative interaction between an integral membrane protein and the peripheral cytoskeleton and indicate that this linkage may be regulated by covalent protein phosphorylation. Such interactions may be of general importance in nonerythroid cells.

Cholinesterase evaluation in the prenatal diagnosis of open neural tube defects

Alpha-fetoprotein (AFP) and cholinesterase levels in amniotic fluid were determined and the efficiency of these laboratory tests in the prenatal diagnosis of neural tube defects was examined. Using the AFP test with cut-off levels correlated to gestational age, we have detected 8 cases of neural tube defects and one case of abdominal wall defect in about 1,200 pregnancies; false-negative values were absent. Acetylcholinesterase (AChE) and butyrylcholinesterase activities were measured and the electrophoretic pattern of AChE was examined in 100 amniotic fluid samples. The diagnosis of neural tube defects was always confirmed. There were no diagnostic problems due to blood-contaminated amniotic fluid samples. The results obtained using different quantitative methods for the determination of cholinesterase activity, as well as the potential use of these tests in routine examinations, are discussed.