Marizomib, a proteasome inhibitor for all seasons: preclinical profile and a framework for clinical trials

The proteasome has emerged as an important clinically relevant target for the treatment of hematologic malignancies. Since the Food and Drug Administration approved the first-in-class proteasome inhibitor bortezomib (Velcade) for the treatment of relapsed/refractory multiple myeloma (MM) and mantle cell lymphoma, it has become clear that new inhibitors are needed that have a better therapeutic ratio, can overcome inherent and acquired bortezomib resistance and exhibit broader anti-cancer activities. Marizomib (NPI-0052; salinosporamide A) is a structurally and pharmacologically unique β-lactone-γ-lactam proteasome inhibitor that may fulfill these unmet needs. The potent and sustained inhibition of all three proteolytic activities of the proteasome by marizomib has inspired extensive preclinical evaluation in a variety of hematologic and solid tumor models, where it is efficacious as a single agent and in combination with biologics, chemotherapeutics and targeted therapeutic agents. Specifically, marizomib has been evaluated in models for multiple myeloma, mantle cell lymphoma, Waldenstrom's macroglobulinemia, chronic and acute lymphocytic leukemia, as well as glioma, colorectal and pancreatic cancer models, and has exhibited synergistic activities in tumor models in combination with bortezomib, the immunomodulatory agent lenalidomide (Revlimid), and various histone deacetylase inhibitors. These and other studies provided the framework for ongoing clinical trials in patients with MM, lymphomas, leukemias and solid tumors, including those who have failed bortezomib treatment, as well as in patients with diagnoses where other proteasome inhibitors have not demonstrated significant efficacy. This review captures the remarkable translational studies and contributions from many collaborators that have advanced marizomib from seabed to bench to bedside.

Crystal structure of the tricorn protease reveals a protein disassembly line

The degradation of cytosolic proteins is carried out predominantly by the proteasome, which generates peptides of 7-9 amino acids long. These products need further processing. Recently, a proteolytic system was identified in the model organism Thermoplasma acidophilum that performs this processing. The hexameric core protein of this modular system, referred to as tricorn protease, is a 720K protease that is able to assemble further into a giant icosahedral capsid, as determined by electron microscopy. Here, we present the crystal structure of the tricorn protease at 2.0 A resolution. The structure reveals a complex mosaic protein whereby five domains combine to form one of six subunits, which further assemble to form the 3-2-symmetric core protein. The structure shows how the individual domains coordinate the specific steps of substrate processing, including channelling of the substrate to, and the product from, the catalytic site. Moreover, the structure shows how accessory protein components might contribute to an even more complex protein machinery that efficiently collects the tricorn-released products.

Crystal structure of the 20 S proteasome:TMC-95A complex: a non-covalent proteasome inhibitor

The 20 S proteasome core particle (CP), a multicatalytic protease, is involved in a variety of biologically important processes, including immune response, cell-cycle control, metabolic adaptation, stress response and cell differentiation. Therefore, selective inhibition of the CP will be one possible way to influence these essential pathways. Recently, a new class of specific proteasome inhibitors, TMC-95s, was investigated and we now present a biochemical and crystallographic characterisation of the yeast proteasome core particle in complex with the natural product TMC-95A. This unusual heterocyclic compound specifically blocks the active sites of CPs non-covalently, without modifying the nucleophilic Thr1 residue. The inhibitor is bound to the CP by specific hydrogen bonds with the main-chain atoms of the protein. Analysis of the crystal structure of the complex has revealed which portions of TMC-95s are essential for binding to the proteasome. This will form the basis for the development of synthetic selective proteasome inhibitors as promising candidates for anti-tumoral or anti-inflammatory drugs.

The substrate translocation channel of the proteasome

The core particle (CP) of the yeast proteasome is composed of four heptameric rings of subunits arranged in a hollow, barrel-like structure. We have found that the CP is autoinhibited by the N-terminal tails of the outer (alpha) ring subunits. Crystallographic analysis showed that deletion of the tail of the alpha3 subunit opens a channel into the proteolytically active interior chamber of the CP, thus derepressing peptide hydrolysis. In the latent state of the particle, the tails prevent substrate entry by imposing topological closure on the CP. Inhibition by the alpha subunit tails is relieved upon binding of the regulatory particle to the CP to form the proteasome holoenzyme. Opening of the CP channel by assembly of the holoenzyme is regulated by the ATPase domain of Rpt2, one of 17 subunits in the RP. Thus, open-channel mutations in CP subunits suppress the closed-channel phenotype of an rpt2 mutant. These results identify a specific mechanism for allosteric regulation of the CP by the RP.

A gated channel into the proteasome core particle

The core particle (CP) of the yeast proteasome is composed of four heptameric rings of subunits arranged in a hollow, barrel-like structure. We report that the CP is autoinhibited by the N-terminal tails of the outer (alpha) ring subunits. Crystallographic analysis showed that deletion of the tail of the alpha 3-subunit opens a channel into the proteolytically active interior chamber of the CP, thus derepressing peptide hydrolysis. In the latent state of the particle, the tails prevent substrate entry by imposing topological closure on the CP. Inhibition by the alpha-subunit tails is relieved upon binding of the regulatory particle to the CP to form the proteasome holoenzyme.

Synthesis of bivalent inhibitors of eucaryotic proteasomes

Based on the peculiar spatial array of the active sites in the internal chamber of the multicatalytic proteasome, as derived from the X-ray structure of yeast proteasome, homo- and heterobivalent inhibitors were designed and synthesized to exploit the principle of multivalency for enhancing inhibition potency. Peptidic bis-aldehyde compounds of the octapeptide size were synthesized to address adjacent active sites, whilst a PEG spacer with a statistical length distribution of 19-25 monomers was used to link two identical or different tripeptide aldehydes as binding heads. These bis-aldehyde compounds were synthesized applying both methods in solution and solid phase peptide synthesis. Bivalent binding was observed only for the PEG-spaced inhibitors suggesting that binding from the primed side prevents hemiacetal formation with the active site threonine residue.

How an inhibitor of the HIV-I protease modulates proteasome activity

The human immunodeficiency virus, type I protease inhibitor Ritonavir has been used successfully in AIDS therapy for 4 years. Clinical observations suggested that Ritonavir may exert a direct effect on the immune system unrelated to inhibition of the human immunodeficiency virus, type I protease. In fact, Ritonavir inhibited the major histocompatibility complex class I restricted presentation of several viral antigens at therapeutically relevant concentrations (5 microM). In search of a molecular target we found that Ritonavir inhibited the chymotrypsin-like activity of the proteasome whereas the tryptic activity was enhanced. In this study we kinetically analyzed how Ritonavir modulates proteasome activity and what consequences this has on cellular functions of the proteasome. Ritonavir is a reversible effector of proteasome activity that protected the subunits MB-1 (X) and/or LMP7 from covalent active site modification with the vinyl sulfone inhibitor(125)I-NLVS, suggesting that they are the prime targets for competitive inhibition by Ritonavir. At low concentrations of Ritonavir (5 microM) cells were more sensitive to canavanine but proliferated normally whereas at higher concentrations (50 microM) protein degradation was affected, and the cell cycle was arrested in the G(1)/S phase. Ritonavir thus modulates antigen processing at concentrations at which vital cellular functions of the proteasome are not yet severely impeded. Proteasome modulators may hence qualify as therapeutics for the control of the cytotoxic immune response.

The catalytic sites of 20S proteasomes and their role in subunit maturation: a mutational and crystallographic study

We present a biochemical and crystallographic characterization of active site mutants of the yeast 20S proteasome with the aim to characterize substrate cleavage specificity, subunit intermediate processing, and maturation. beta1(Pre3), beta2(Pup1), and beta5(Pre2) are responsible for the postacidic, tryptic, and chymotryptic activity, respectively. The maturation of active subunits is independent of the presence of other active subunits and occurs by intrasubunit autolysis. The propeptides of beta6(Pre7) and beta7(Pre4) are intermediately processed to their final forms by beta2(Pup1) in the wild-type enzyme and by beta5(Pre2) and beta1(Pre3) in the beta2(Pup1) inactive mutants. A role of the propeptide of beta1(Pre3) is to prevent acetylation and thereby inactivation. A gallery of proteasome mutants that contain active site residues in the context of the inactive subunits beta3(Pup3), beta6(Pre7), and beta7(Pre4) show that the presence of Gly-1, Thr1, Asp17, Lys33, Ser129, Asp166, and Ser169 is not sufficient to generate activity.

Proteasome beta-type subunits: unequal roles of propeptides in core particle maturation and a hierarchy of active site function

The 26 S proteasome is a large eukaryotic protease complex acting in ubiquitin-mediated degradation of abnormal and many short-lived, regulatory proteins. Its cylinder-shaped 20 S proteolytic core consists of two sets, each of seven different alpha and beta-type subunits arranged into two outer alpha-rings surrounding two inner beta-rings. The beta-rings form a central chamber with a total of six proteolytically active centers located in the beta1, beta2 and beta5 subunits. Activation of these subunits occurs during late assembly stages through intramolecular precursor autolysis removing propeptides attached to Thr1, which then serves as N-terminal nucleophile in substrate hydrolysis. This maturation entails intermolecular cleavage of propeptides residing in two of the non-active beta-type subunits, beta6 and beta7. In yeast, deletion of the beta5/Pre2 propeptide was shown to be lethal by preventing assembly of the core particle, while its expression as a separate entity restored growth. We investigated the role of the yeast beta1/Pre3, beta2/Pup1 and beta7/Pre4 propeptides by expressing the mature subunit moieties without propeptides as C-terminal fusions to ubiquitin. In all cases, viable strains could be generated. Deletion of the beta1/Pre3 and beta7/Pre4 propeptides did not affect cell growth, but deletion of the beta2/Pup1 propeptide led to poor growth, which was partially restored by co-expression of the free propeptide. Gain of proteolytic activity of beta1/Pre3 and beta2/Pup1 was abolished or drastically reduced, respectively, if their respective propeptides were not N-terminally bound. We detected N -alpha-acetylation at Thr1 of beta1/Pre3 as cause for its inactivation. Thus, one role for the propeptides of active beta-type subunits might be to protect the mature subunits catalytic Thr1 alpha-amino group from acetylation. The beta2/Pup1 propeptide was, in addition, required for efficient 20 S proteasome maturation, as revealed by the accumulation of beta7/Pre4 precursor and intermediate processing forms upon expression of mature beta2/Pup1. Finally, growth phenotypes resulting from expression of active site mutated beta-type subunits uncoupled from their propeptides allowed us to deduce the hierarchy of the importance of individual subunit activities for proteasomal function as follows: beta5/Pre2>>beta2/Pup1>/=beta1/Pre3.

The proteasome

Proteasomes are large multisubunit proteases that are found in the cytosol, both free and attached to the endoplasmic reticulum, and in the nucleus of eukaryotic cells. Their ubiquitous presence and high abundance in these compartments reflects their central role in cellular protein turnover. Proteasomes recognize, unfold, and digest protein substrates that have been marked for degradation by the attachment of a ubiquitin moiety. Individual subcomplexes of the complete 26S proteasome are involved in these different tasks: The ATP-dependent 19S caps are believed to unfold substrates and feed them to the actual protease, the 20S proteasome. This core particle appears to be more ancient than the ubiquitin system. Both prokaryotic and archaebacterial ancestors have been identified. Crystal structures are now available for the E. coli proteasome homologue and the T. acidophilum and S. cerevisiae 20S proteasomes. All three enzymes are cylindrical particles that have their active sites on the inner walls of a large central cavity. They share the fold and a novel catalytic mechanism with an N-terminal nucleophilic threonine, which places them in the family of Ntn (N terminal nucleophile) hydrolases. Evolution has added complexity to the comparatively simple prokaryotic prototype. This minimal proteasome is a homododecamer made from two hexameric rings stacked head to head. Its heptameric version is the catalytic core of archaebacterial proteasomes, where it is sandwiched between two inactive antichambers that are made up from a different subunit. In eukaryotes, both subunits have diverged into seven different subunits each, which are present in the particle in unique locations such that a complex dimer is formed that has six active sites with three major specificities that can be attributed to individual subunits. Genetic, biochemical, and high-resolution electron microscopy data, but no crystal structures, are available for the 19S caps. A first step toward a mechanistic understanding of proteasome activation and regulation has been made with the elucidation of the X-ray structure of the alternative, mammalian proteasome activator PA28.

Bivalency as a principle for proteasome inhibition

The proteasome, a multicatalytic protease, is known to degrade unfolded polypeptides with low specificity in substrate selection and cleavage pattern. This lack of well-defined substrate specificities makes the design of peptide-based highly selective inhibitors extremely difficult. However, the x-ray structure of the proteasome from Saccharomyces cerevisiae reveals a unique topography of the six active sites in the inner chamber of the protease, which lends itself to strategies of specific multivalent inhibition. Structure-derived active site separation distances were exploited for the design of homo- and heterobivalent inhibitors based on peptide aldehyde head groups and polyoxyethylene as spacer element. Polyoxyethylene was chosen as a flexible, linear, and proteasome-resistant polymer to mimic unfolded polypeptide chains and thus to allow access to the proteolytic chamber. Spacer lengths were selected that satisfy the inter- and intra-ring distances for occupation of the active sites from the S subsites. X-ray analysis of the proteasome/bivalent inhibitor complexes confirmed independent recognition and binding of the inhibitory head groups. Their inhibitory potencies, which are by 2 orders of magnitude enhanced, compared with pegylated monovalent inhibitors, result from the bivalent binding. The principle of multivalency, ubiquitous in nature, has been successfully applied in the past to enhance affinity and avidity of ligands in molecular recognition processes. The present study confirms its utility also for inhibition of multicatalytic protease complexes.

Bifunctional inhibitors of the trypsin-like activity of eukaryotic proteasomes

BACKGROUND

The 20S proteasome is a multicatalytic protease complex that exhibits trypsin-like, chymotrypsin-like and post-glutamyl-peptide hydrolytic activities associated with the active sites of the beta2, beta5 and beta1 subunits, respectively. Modulation of these activities using inhibitors is essential for a better understanding of the proteasome's mechanism of action. Although there are highly selective inhibitors of the proteasome's chymotryptic activity, inhibitors of similar specificity have not yet been identified for the other activities.

RESULTS

The X-ray structure of the yeast proteasome reveals that the sidechain of Cys118 of the beta3 subunit protrudes into the S3 subsite of the beta2 active site. The location of this residue was exploited for the rational design of bidentated inhibitors containing a maleinimide moiety at the P3 position for covalent linkage to the thiol group and a carboxy-terminal aldehyde group for hemiacetal formation with the Thr1 hydroxyl group of the active site. Structure-based modelling was used to determine the optimal spacing of the maleinimide group from the P2-P1 dipeptide aldehydes and the specificity of the S1 subsite was exploited to limit the inhibitory activity to the beta2 active site. X-ray crystallographic analysis of a yeast proteasome-inhibitor adduct confirmed the expected irreversible binding of the inhibitor to the P3 subsite.

CONCLUSIONS

Maleoyl-beta-alanyl-valyl-arginal is a new type of inhibitor that is highly selective for the trypsin-like activity of eukaryotic proteasomes. Despite the reactivity of the maleinimide group towards thiols, and therefore the limited use of this inhibitor for in vitro studies, it might represent an interesting new biochemical tool.

Cleavage motifs of the yeast 20S proteasome beta subunits deduced from digests of enolase 1

The 436-amino acid protein enolase 1 from yeast was degraded in vitro by purified wild-type and mutant yeast 20S proteasome particles. Analysis of the cleavage products at different times revealed a processive degradation mechanism and a length distribution of fragments ranging from 3 to 25 amino acids with an average length of 7 to 8 amino acids. Surprisingly, the average fragment length was very similar between wild-type and mutant 20S proteasomes with reduced numbers of active sites. This implies that the fragment length is not influenced by the distance between the active sites, as previously postulated. A detailed analysis of the cleavages also allowed the identification of certain amino acid characteristics in positions flanking the cleavage site that guide the selection of the P1 residues by the three active beta subunits. Because yeast and mammalian proteasomes are highly homologous, similar cleavage motifs might be used by mammalian proteasomes. Therefore, our data provide a basis for predicting proteasomal degradation products from which peptides are sampled by major histocompatibility complex class I molecules for presentation to cytotoxic T cells.

Contribution of proteasomal beta-subunits to the cleavage of peptide substrates analyzed with yeast mutants

Proteasomes generate peptides that can be presented by major histocompatibility complex (MHC) class I molecules in vertebrate cells. Using yeast 20 S proteasomes carrying different inactivated beta-subunits, we investigated the specificities and contributions of the different beta-subunits to the degradation of polypeptide substrates containing MHC class I ligands and addressed the question of additional proteolytically active sites apart from the active beta-subunits. We found a clear correlation between the contribution of the different subunits to the cleavage of fluorogenic and long peptide substrates, with beta5/Pre2 cleaving after hydrophobic, beta2/Pup1 after basic, and beta1/Pre3 after acidic residues, but with the exception that beta2/Pup1 and beta1/Pre3 can also cleave after some hydrophobic residues. All proteolytic activities including the "branched chain amino acid-preferring" component are associated with beta5/Pre2, beta1/Pre3, or beta2/Pup1, arguing against additional proteolytic sites. Because of the high homology between yeast and mammalian 20 S proteasomes in sequence and subunit topology and the conservation of cleavage specificity between mammalian and yeast proteasomes, our results can be expected to also describe most of the proteolytic activity of mammalian 20 S proteasomes leading to the generation of MHC class I ligands.

Conformational constraints for protein self-cleavage in the proteasome

The proteasome is the central enzyme of protein degradation in the cytosol and the nucleus. It is involved in the removal of abnormal, misfolded or incorrectly assembled proteins, in the processing or degradation of transcriptional regulators in stress response, in degradation of cyclins in cell-cycle control, in the destruction of transcription factors or metabolic enzymes in cell differentiation and metabolic response, and in MHC class I mediated cellular immune response. By the analysis of the crystal and molecular structures of the 20 S proteasomes from the archaeon Thermoplasma acidophilum and from yeast it was shown that the beta-type subunits in which the proteolytic activities reside are members of the N-terminal nucleophile (Ntn) protein family. They are synthesized as proproteins and become active by autoprocessing at a Gly-1-Thr1 bond. The Thr1Ala mutant of subunit beta1/Pre3 of the 20 S proteasome from yeast is unable to autolyse. Its crystal and molecular structure at 2.2 A resolution described here shows that the pro-segment adopts a well-defined gamma-turn conformation at Gly-1 and provides a first view at an autolysis site in Ntn hydrolases. The Gly-1 carbonyl oxygen displays two hydrogen bonds. The modelled Thr1 side-chain is located above the gamma-turn bulge such that addition of its nucleophilic hydroxyl group to the electrophilic Gly-1 carbonyl carbon atom may proceed by very small motions. The pro-segment binding site and the catalytic site provide a rigid structural framework and appropriate hydrogen bond donors for this reaction. The same structure also supports addition of the Thr1 hydroxyl group to the carbonyl carbon atom of Leu-2 as a model for the first step in substrate hydrolysis by the proteasome.

Preliminary results achieved by a computer-assisted system for controlled balloon dilatation of coronary and peripheral arteries

In percutaneous balloon angioplasty the extent of trauma to the vessel as determined by slope of balloon inflation, peak pressure, and inflation time is crucial to the success of the intervention. These parameters are still not standardized and hence open to the operator. To elucidate this problem, a computer-assisted PTCA system (CAPS) was developed. CAPS is composed of a motor driven unit, a central processing and power unit, and a notebook. A syringe is clamped onto the motor unit and connected to a pressure gauge. CAPS may be linked to all types of balloon catheters. The notebook allows for preselection of peak pressure, slope of pressure increase, and inflation time. During balloon inflation, adjustments are made in a closed-loop system. On a screen, the inflation process is supervised in digital numbers and analogous curves. After the procedure, patient data and inflation curves may be recalled for analysis. In conclusion, CAPS by controlled inflation theoretically may reduce the mechanical trauma to the arteries. Further refinements should aim at gaining information on the lesions' characteristics and on the dilatation process itself.

Synthesis, kinetic characterization and X-ray analysis of peptide aldehydes as inhibitors of the 20S proteasomes from Thermoplasma acidophilum and Saccharomyces cerevisiae

A comparative kinetic characterization of the peptide aldehydes Ac-Leu-Leu-X-H [X = Trp, Tyr and Tyr(tBu)] and Z-Gly-Pro-Gly-Gly-Leu-Leu-Nle-H as inhibitors of the chymotryptic activity of 20S proteasomes from the archaebacterium T. acidophilum and yeast S. cerevisiae revealed significantly differentiated inhibitory potencies that can be rationalized on the basis of X-ray crystallographic data.

Crystal structure of heat shock locus V (HslV) from Escherichia coli

Heat shock locus V (HslV; also called ClpQ) is the proteolytic core of the ATP-dependent protease HslVU in Escherichia coli. It has sequence similarity with the beta-type subunits of the eukaryotic and archaebacterial proteasomes. Unlike these particles, which display 72-point symmetry, it is a dimer of hexamers with 62-point symmetry. The crystal structure of HslV at 3.8-A resolution, determined by isomorphous replacement and symmetry averaging, shows that in spite of the different symmetry of the particle, the fold and the contacts between subunits are conserved. A tripeptide aldehyde inhibitor, acetyl-Leu-Leu-norleucinal, binds to the N-terminal threonine residue of HslV, probably as a hemiacetal, relating HslV also functionally to the proteasomes of archaea and eukaryotes.

Structure of 20S proteasome from yeast at 2.4 A resolution

The crystal structure of the 20S proteasome from the yeast Saccharomyces cerevisiae shows that its 28 protein subunits are arranged as an (alpha1...alpha7, beta1...beta7)2 complex in four stacked rings and occupy unique locations. The interior of the particle, which harbours the active sites, is only accessible by some very narrow side entrances. The beta-type subunits are synthesized as proproteins before being proteolytically processed for assembly into the particle. The proforms of three of the seven different beta-type subunits, beta1/PRE3, beta2/PUP1 and beta5/PRE2, are cleaved between the threonine at position 1 and the last glycine of the pro-sequence, with release of the active-site residue Thr 1. These three beta-type subunits have inhibitor-binding sites, indicating that PRE2 has a chymotrypsin-like and a trypsin-like activity and that PRE3 has peptidylglutamyl peptide hydrolytic specificity. Other beta-type subunits are processed to an intermediate form, indicating that an additional nonspecific endopeptidase activity may exist which is important for peptide hydrolysis and for the generation of ligands for class I molecules of the major histocompatibility complex.

[Seroepidemiological considerations of the incidence of viral hepatitis C in some population groups]

In the interval 1985-1994, in the Iaşi district, the reported cases of viral hepatitis (VH) have recorded annual morbidity rates ranging between 67/100,000 inhabitants in 1993 and 373/100,000 in 1990. VH attributed to HAV and HBV has represented, with yearly differences, 62% to 94% of all cases. Posttransfusion viral hepatitis (PTVH) has determined a morbidity of 0.51/100,000 inhabitants in 1986 and 8.34/100,000 in 1994. PTVH without AgHBs ranged from 16.3% in 1993 to 94.0% in 1987, as compared to 6.0% in 1987 and 1988 and 75.0% in 1985 for PTVH with AgHBs. In the interval under study 70.9% of the PTVH cases were most likely determined by HCV and 28.9% by HBV (AgHBs+). From all PTVH cases, 64.0% were from urban areas, 59.3% were females, 92.5% belonged to over 20 years age groups, and 31.3% were industrial workers, the remainder belonging to other 5 occupational groups. In 241 patients (18.2%) admitted for liver disorders, posttransfusion hepatitis included, AcHCV was present in 39.4%, of which 45.2% belonged to the age groups 20-60 years. The results of some investigations carried out on 4471 blood donors (72.4% males, 85.4% aged between 21 ad 50 years, 86.4% from urban areas, 62.1% workers in industry and building) are presented. Out of these, 217 (4.9%) presented to hepatitis C virus (AcHCV). Occupational distribution of AcHCV possessors shows that 44.2% are workers in the heavy industry, 14.8% in the light industry and 12.9% unemployed. Sera were tested by Monolisa New Antigens, and those with AcHCV were reassessed with Monolisa, Murex anti HCV, ORTO-HCV 3.0 and confirmed by Immunoblot DECISCAN, with 5 antigens.

[Epidemiological observations on the evolution of influenza in the city of Iaşi in the epidemic season of 1993-1994]

The epidemiological, clinical and laboratory data of influenza and other respiratory diseases recorded during the epidemic season 1993-1994, as they resulted from the comparative analysis of the cases reported weekly and those recorded through the "sentinel" collectivities method, are presented. The findings at admissions to the Infectious Diseases Hospital, Military Hospital, Diagnosis and Treatment Centre for Pupils and Students and the solicitation for medical care at the Emergency Ambulance Service were also interpreted. The involvement of A/Beijing/32/92/(H3N2) influenza virus was confirmed by evidencing the seroconversion on two serum samples tested through RIH, while for others antigens anamnestic reactions were recorded. The influenza epidemic had affected all age groups, with horizontal extension, a first rise in December 1993 followed by the decline determined by winter vacation being notice. A second epidemic rise, much stronger, started beginning with the last month of January and reached a peak at mid February, followed by a marked decline.

Efficacy of multidisciplinary epidemiological screening in the primary prevention of essential arterial hypertension

An epidemiological screening of 8011 industrial workers and 7090 pupils made possible the active detection of some risk factors carriers and of those individuals with borderline essential arterial hypertension (BEAHT) and essential arterial hypertension disease (EAHTD). It was noticed that the association of 2-4 risk factors is more common in the subjects with BEAHT or EAHTD, fact indicating their increased aggressivity in the various types of associations present in the same carrier. In the worker series a prevalence of 16.2%-18.0% for BEAHT and 6.3%-7.1% for EAHTD as compared to 4.3%-6.0% and 4.9%-5.3%, respectively, in the pupil series were recorded. The epidemiological screening had a strong educational effect, reflected in an increased cooperation of the screened population, and revealed the fact that the risk factor carrier state and the increased arterial pressure levels were ignored, at long term, by 50-90% of the investigated subjects.

[Antimicrobial activities of organic zinc compounds]

Taking into account the competitive action of zinc towards other ion essential for pathogenic germs metabolism, the complex erythromycin-zinc, zinc salts of sulfamethoxydiazine, sulfanilamide, sulfacetimide, sulfathiazole as well as the Mannich basis of sulfamethoxydiazine were synthetized. The antimicrobial action towards gram-positive, gram-negative pathogens and fungi was tested by the classic diffusiometric method. An increased antimicrobial action for the Mannich basis of sulfamethoxydiazine and for the zinc salt of sulfamethoxydiazine, alone or in association with metronidazole--chemotherapeutic agent used in the infections with anaerobic organisms was found. A significant antimicrobial action was also found for the complex erythromycin-zinc and zinc salts of sulfacetimide and sulfathiazole.

[Epidemiological observations on alcohol consumption as a risk factor in essential arterial hypertension]

The results of the epidemiological investigations in industrial environment in view of demonstrating some relations between alcohol and salt consumption, tobacco smoking, over weight and prevalence of essential arterial hypertension are presented. The obtained data indicate that in 471 workers in smelting the prevalence of alcohol consumers (1-3 intakes/day of strong alcohol) was of 15% as compared to 28.4% in 559 workers in an unit for building equipment, 4% in the 1188 women, working in ready-made and knitted wear mills and 19.8 and 4.5% in men and women, respectively, working in administrative services. Both the prevalence of daily strong alcohol consumption and of the other considered factors are significantly increasing with age. An increased prevalence of alcohol consumption associated with tobacco smoking, salt consumption and over weight was found in the hypertensive subjects as compared to the controls. The obtained data are useful in elaborating primary prevention programs of essential arterial hypertension.

[Epidemiological observations on the significance of the relations between elevated values of essential arterial pressure in schoolchildren and their parents]

The results of an epidemiological screening of 1,228 parents and 614 children, pupils in the V-XII forms of 12 schools of different types, are presented. It is suggested that when parents present elevated blood pressure values their children, although normotensive, are at high risk, especially in case more risk factors are present. The relation hypertensive parents--hypertensive offsprings was strongly significant. In the hypertensive children with normotensive parents the high frequency of some life-style dependent risk factors is discussed. The relationship between risk factors and morbidity by essential hypertension both in parents and their offsprings and the need of primary and secondary prevention programs for pupils are underlined.

[Intervention associated with risk factors for essential arterial hypertension. II. Epidemiologic observations of schoolchildren]

Based on an epidemiological screening of 6411 pupils from 7 schools of different types, the frequency and intensity of the association of 8 risk factors for essential hypertension in a series with increased blood pressure values and in a normotensive one was compared. The frequency of the various studied risk factors was significant especially in the pupils with increased blood pressure values. The average number of risk factors in the two series was unsignificant. The intensity of 2, 3 or 4 risk factors different associations was more marked in the pupils with increased blood pressure values than in the controls. Some risk factors proved to be more frequently involved in multifactorial associations. The importance of such studies for the elaboration of prevention programmes in underlined.

[Epidemiology of essential arterial hypertension in collectives of schoolchildren. The prevalence of blood pressure changes]

7,917 pupils in schools, between 10-19 years old, of both sexes, were investigated within an epidemiologic screening, performed in the school milieu, for detecting the prevalence of some risk factors (RF) and of the AT modifications with a view to work out the programmes for the essential arterial hypertension (EAHT) primary prevention. 84.4% of all the pupils in the Vth--VIIIth forms and 93.9 pupils in the IXth--XIIth forms were included in the screening. 422 cases of labile arterial hypertension (LAHT) (5.1%) and 457 of benign arterial hypertension (BATH) (54%) were found. In the children with normal arterial hypertension (NAHT) the following were recorded: 46.5% increases only of the diastolic tension: 44.0% of the systolic-diastolic and 7.1% of the systolic tension respectively. Although present, the differences between the LAHT and BAHT prevalence in the gymnasiums (4.3% and 5.4%) and lyceums (5.5% and 6.4%) are not significant and might be functions of: age, sex, psychomotor development, structure of the respective collectivities, the momentary psychoemotional reactions, lability of the blood pressure, specific to the childhood, several screening difficulties etc. The observations made on the prevalence of the growth of the AT values were correlated with the occurrence at some significant levels of the RF, suggesting the measures to be taken for the steady improvement of the primary and secondary prophylaxis of EAHT in schools.

[Interventions associated with some risk factors for essential arterial hypertension. I. Epidemiologic observations in adults]

The results of an epidemiological screening followed by the investigation of 9 risk factors for essential hypertension in 1218 individuals with increased values of blood pressure are presented. Stress, overweight and dietary preferences for fats and eggs had the incidence especially in, the age groups over 40 years. Both the individuals with borderline hypertension or arterial hypertension and the controls presented 2, 3 or more associated risk factors of variable intensity, the higher values being recorded in the greater than or equal to 40 years age group. When more than 3 risk factors were associated, the increases in systolic and diastolic pressures were significant. The investigation of 7 biochemical constants revealed that 50% of 190 cases with arterial hypertension presented cholesterol levels higher than 220 mg%. Increased total lipids, free fatty acids and triglycerides levels were also recorded. The results plead for multifactorial prevention programmes.