Antihypertensive phytocomplexes of proven efficacy and well-established use: Mode of action and individual characterization of the active constituents.

Hypertension has become the leading risk factor for worldwide cardiovascular diseases. Conventional pharmacological treatment, after both dietary and lifestyle changes, is generally proposed. In this review, we present the antihypertensive properties of phytocomplexes from thirteen plants, long ago widely employed in ethnomedicines and, in recent years, increasingly evaluated for their activity in vitro and in vivo, also in humans, in comparison with synthetic drugs acting on the same systems. Here, we focus on the demonstrated or proposed mechanisms of action of such phytocomplexes and of their constituents proven to exert cardiovascular effects. Almost seventy phytochemicals are described and scientifically sound pertinent literature, published up to now, is summarized. The review emphasizes the therapeutic potential of these natural substances in the treatment of the 'high normal blood pressure' or 'stage 1 hypertension', so-named according to the most recent European and U.S. guidelines, and as a supplementation in more advanced stages of hypertension, however needing further validation by clinical trial intensification.

First Results from CUORE: A Search for Lepton Number Violation via 0νßß Decay of

The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number-violating process: ^{130}Te neutrinoless double-beta decay. Examining a total TeO_{2} exposure of 86.3 kg yr, characterized by an effective energy resolution of (7.7±0.5) keV FWHM and a background in the region of interest of (0.014±0.002) counts/(keV kg yr), we find no evidence for neutrinoless double-beta decay. Including systematic uncertainties, we place a lower limit on the decay half-life of T_{1/2}^{0ν}(^{130}Te)>1.3×10^{25} yr (90% C.L.); the median statistical sensitivity of this search is 7.0×10^{24} yr. Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find T_{1/2}^{0ν}(^{130}Te)>1.5×10^{25} yr (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find m_{ßß}<(110-520) meV, where the range reflects the nuclear matrix element estimates employed.

Calcium-Sensing Receptors of Human Astrocyte-Neuron Teams: Amyloid-ß-Driven Mediators and Therapeutic Targets of Alzheimer's Disease.

It is generally assumed that the neuropathology of sporadic (late-onset or nonfamilial) Alzheimer's disease (AD) is driven by the overproduction and spreading of first Amyloid-ßx-42 (Aß42) and later hyperphosphorylated (hp)-Tau oligomeric "infectious seeds". Hitherto, only neurons were held to make and spread both oligomer types; astrocytes would just remove debris. However, we have recently shown that exogenous fibrillar or soluble Aß peptides specifically bind and activate the Ca(2+)-sensing receptors (CaSRs) of untransformed human cortical adult astrocytes and postnatal neurons cultured in vitro driving them to produce, accrue, and secrete surplus endogenous Aß42. While the Aß-exposed neurons start dying, astrocytes survive and keep oversecreting Aß42, nitric oxide (NO), and vascular endothelial growth factor (VEGF)-A. Thus astrocytes help neurons' demise. Moreover, we have found that a highly selective allosteric CaSR agonist ("calcimimetic"), NPS R-568, mimics the just mentioned neurotoxic actions triggered by Aß●CaSR signaling. Contrariwise, and most important, NPS 2143, a highly selective allosteric CaSR antagonist ("calcilytic"), fully suppresses all the Aß●CaSR signaling-driven noxious actions. Altogether our findings suggest that the progression of AD neuropathology is promoted by unceasingly repeating cycles of accruing exogenous Aß42 oligomers interacting with the CaSRs of swelling numbers of astrocyte-neuron teams thereby recruiting them to overrelease additional Aß42 oligomers, VEGF-A, and NO. Calcilytics would beneficially break such Aß/CaSR-driven vicious cycles and hence halt or at least slow the otherwise unstoppable spreading of AD neuropathology.

1,4-Dihydropyridine scaffold in medicinal chemistry, the story so far and perspectives (part 2): action in other targets and antitargets.

1,4-Dihydropyridines were introduced in the last century for the treatment of coronary diseases. Then medicinal chemists decorated the 1,4-DHP nucleus, the most studied scaffold among L-type calcium channel blockers, achieving diverse activities at several receptors, channels and enzymes. We already described (Ioan et al. Curr. Med. Chem. 2011, 18, 4901-4922) the effects of 1,4-DHPs at ion channels and G-protein coupled receptors. In this paper we continue the analysis of the wide range of biological effects exerted by compounds belonging to this chemical class. In particular, focus is given to the ability of 1,4-DHPs to revert multi drug resistance that, after over 20 years of research, continues to be of great interest. We also describe activities on other targets and the action of 1,4-DHPs against several diseases. Finally, we report and review the interaction of 1,4-DHPs with the hERG channel, transporters and phase I metabolizing enzymes. This work is a starting point for further exploration of the 1,4-DHP core activities on targets, off-targets and antitargets.

1,4-Dihydropyridine scaffold in medicinal chemistry, the story so far and perspectives (part 1): action in ion channels and GPCRs.

Since the pioneering studies of Fleckenstein and co-workers, L-Type Calcium Channel (LTCC) blockers have attracted large interest due to their effectiveness in treating several cardiovascular diseases. Medicinal chemists achieved high potency and tissue selectivity by decorating the 1-4-DHP nucleus, the most studied scaffold among LTCC blockers. Nowadays it is clear that the 1,4-DHP nucleus is a privileged scaffold since, when appropriately substituted, it can selectively modulate diverse receptors, channels and enzymes. Therefore, the 1,4-DHP scaffold could be used to treat various diseases by a single-ligand multi-target approach. In this review, we describe the structure-activity relationships of 1,4-DHPs at ion channels, G-protein coupled receptors, and outline the potential for future therapeutic applications.

@neurIST complex information processing toolchain for the integrated management of cerebral aneurysms.

Cerebral aneurysms are a multi-factorial disease with severe consequences. A core part of the European project @neurIST was the physical characterization of aneurysms to find candidate risk factors associated with aneurysm rupture. The project investigated measures based on morphological, haemodynamic and aneurysm wall structure analyses for more than 300 cases of ruptured and unruptured aneurysms, extracting descriptors suitable for statistical studies. This paper deals with the unique challenges associated with this task, and the implemented solutions. The consistency of results required by the subsequent statistical analyses, given the heterogeneous image data sources and multiple human operators, was met by a highly automated toolchain combined with training. A testimonial of the successful automation is the positive evaluation of the toolchain by over 260 clinicians during various hands-on workshops. The specification of the analyses required thorough investigations of modelling and processing choices, discussed in a detailed analysis protocol. Finally, an abstract data model governing the management of the simulation-related data provides a framework for data provenance and supports future use of data and toolchain. This is achieved by enabling the easy modification of the modelling approaches and solution details through abstract problem descriptions, removing the need of repetition of manual processing work.

Ligands of diltiazem binding site: an overview of some chemotypes.

The diltiazem binding site of L-type calcium channels is the least characterized to date. In this paper, we present some of the available chemotypes that bind to the benzothiazepine binding site: natural compounds, compounds synthesized by varying the benzothiazepine scaffold, and compounds discovered by means of computational approaches.

Prevalence of virulence-associated genotypes of Helicobacter pylori and correlation with severity of gastric pathology in patients from western Sicily, Italy.

In a bacterium like Helicobacter pylori, which is characterized by a recombinant population structure, the associated presence of genes encoding virulence factors might be considered an expression of a selective advantage conferred to strains with certain genotypes and, therefore, a potentially useful tool for predicting the clinical outcome of infections. However, differences in the geographical and ethnic prevalence of the H. pylori virulence-associated genotypes can affect their clinical predictive value and need to be considered in advance. In this study we carried out such an evaluation in a group of patients living in Sicily, the largest and most populous island in the Mediterranean Sea. cagA, vacA, babA2, hopQ, oipA, sabA, and hopZ were the H. pylori virulence-associated genes assayed; their presence, expression status or allelic homologs were detected in H. pylori DNA samples and/or isolated strains, obtained by gastric biopsy from 90 Sicilian patients with chronic gastritis, inactive (n = 37), active (n = 26), or active with peptic ulcer (n = 27). Genotypes cagA (+), vacAs1, vacAm1, babA2 (+), and hopQ I, I/II were identified in 51.8, 80.4, 35.2, 47.3, and 67.7% of the different samples respectively. Only these genotypes were associated with each other and with the active form of chronic gastritis, irrespective of the presence of a peptic ulcer. In our isolates their prevalence was more similar to values observed in the north of Italy and France than to those observed in Spain or other Mediterranean countries that are closer and climatically more similar to western Sicily.

@neurIST - chronic disease management through integration of heterogeneous data and computer-interpretable guideline services.

This paper presents an overview of computerised decision support for clinical practice. The concept of computer-interpretable guidelines is introduced in the context of the @neurIST project, which aims at supporting the research and treatment of asymptomatic unruptured cerebral aneurysms by bringing together heterogeneous data, computing and complex processing services. The architecture is generic enough to adapt it to the treatment of other diseases beyond cerebral aneurysms. The paper reviews the generic requirements of the @neurIST system and presents the innovative work in distributing executable clinical guidelines.

European Sero-Epidemiology Network: standardisation of the assay results for pertussis.

A standardisation process was developed in order to compare and harmonize serological results of pertussis toxin (PT) antibody measurements performed by laboratories using different technical procedures for detection. This involved the development of a common panel, of sera by a designed reference centre, the distribution of the panel to each participating laboratory for testing with their routine methods, the comparison of the obtained results to those of the reference centre, and the calculation of standardisation equations by regressing the quantitative results against those of the reference centre. As a cut-off indicative of protection against pertussis has not yet been defined, a particular emphasis was laid upon achieving standardisation of high titre results that would allow epidemiological evaluations based on the estimation of the incidence of recent infections rather than on the traditional approach of determining the population immunity profile. A generally good agreement was achieved between the participating laboratories, all using ELISA procedures very similar in many crucial aspects, and standardisation equations were produced useful to enable inter-country comparison during the next stages of the European Sero-Epidemiology Network (ESEN) project concerning the serological surveillance of immunity to pertussis in Europe.

Analogous IgG subclass response to pertussis toxin in vaccinated children, healthy or affected by whooping cough.

The study of antigen specific IgG subclass distribution during disease, or during any other natural or artificial immunisation, can provide useful information on the kind of the immune response and the expected levels of protection. This is particularly true for diseases, such as pertussis in which the mechanisms underlying specific defence are still not completely understood. An investigation was therefore performed to evaluate the IgG subclass response to pertussis toxin (PT) in sera from 89 healthy vaccinated children and 131 vaccinated or unvaccinated children convalescent after a confirmed B. pertussis symptomatic infection. Antibody titres were expressed in arbitrary ELISA units/ml, and statistical analyses were performed. In unvaccinated convalescent children IgG1 and IgG3 were prevalent whereas in children immunised with two different acellular pertussis (aP) vaccines, both healthy and convalescent, IgG1, IgG2 and IgG4 antibodies were mainly produced. Maintenance of the same anti-PT antibody response pattern in healthy acellular pertussis vaccine recipients and in vaccinated children who later acquire the disease is an interesting result indicative of the priming effect induced by these vaccines in the direction of a relatively higher Th2 cell-polarisation of the immune response.

Design, synthesis, and biological activity of methoctramine-related polyamines as putative G(i) protein activators.

The universal template approach provided a prospect of modifying methoctramine (2) structure. Thus, polyamines 3-7 were designed in which the flexibility of the diaminohexane spacer of 2 was replaced by a bipiperidinyl moiety. In electrically stimulated guinea pig left atria, these novel polyamines, unlike prototype 2, displayed a potent intrinsic activity, which was in contrast with the muscarinic antagonism shown in binding studies by some of them (3 and 4) and was inhibited by benzalkonium chloride, an inhibitor of G(i) proteins.

Structure-activity relationships and optimisation of the selective MDR modulator 2-(3,4-dimethoxyphenyl)-5-(9-fluorenylamino)-2-(methylethyl) pentanenitrile and its N-methyl derivative.

Several ring-substituted derivatives of previously studied MDR inhibitors 2-(3,4-dimethoxyphenyl)-5-(9-fluorenylamino)-2-(methylethyl)pentanenitrile and 2-(3,4-dimethoxyphenyl)-5-[(9-fluorenyl)-N-methylamino]-2-(methylethyl)pentanenitrile have been synthesised and studied with the aim of optimising activity and selectivity. The results show that MDR inhibition is scarcely sensitive to modulation of the electronic properties of the fluorene ring. Even if dramatic improvement was not obtained, one of the compounds (2) showed improved potency and selectivity with respect to the leads and appears to be a better candidate for drug development.

Analogues of polyamine alkaloids and their synthetic advantages.

Several polyamine derivatives were synthesized in order to produce novel antagonists of muscular nicotinic acetylcholine receptors. Their affinities were compared with those of philanthotoxin PhTX-343.

Analysis of the muscarinic receptor subtype mediating inhibition of the neurogenic contractions in rabbit isolated vas deferens by a series of polymethylene tetra-amines.

The pharmacological characteristics of the presynaptic muscarinic receptor subtype, which mediates inhibition of the neurogenic contractions in the prostatic portion of rabbit vas deferens, have been investigated by using a series of polymethylene tetra-amines, which were selected for their ability to differentiate among muscarinic receptor subtypes. It was found that all tetra-amines antagonized McN-A-343-induced inhibition in electrically stimulated rabbit vas deferens in a competitive manner and with affinity values (pA:(2)) ranging between 6.27+/-0.09 (spirotramine) and 8.51+/-0.02 (AM170). Competition radioligand binding studies, using native muscarinic receptors from rat tissues (M(1), cortex; M(2), heart; M(3), submaxillary gland) or from NG 108-15 cells (M(4)) and human cloned muscarinic M(1)-M(4) receptors expressed in CHO-K1 cells, were undertaken with the same tetra-amines employed in functional assays. All antagonists indicated a one-site fit. The affinity estimates (pK:(i)) of tetra-amines calculated in binding assays using native receptors were similar to those obtained using cloned receptors. Among these compounds some displayed selectivity between muscarinic receptor subtypes, indicating that they may be valuable tools in receptor characterization. Spirotramine was selective for M(1) receptors versus all other subtypes (pK:(i) native: M(1), 7.32+/-0.10; M(2), 6.50+/-0.11; M(3), 6.02+/-0.13; M(4), 6.28+/-0.16; pK:(i) cloned: M(1), 7.69+/-0.08; M(2), 6.22+/-0.14; M(3), 6.11+/-0.16; 6.35+/-0.11) whereas CC8 is highly selective for M(2) receptors versus the other subtypes (pK:(i) native: M(1), 7.50+/-0.04; M(2), 9.01+/-0.12; M(3), 6.70+/-0.08; M(4), 7.56+/-0.04; pK:(i) cloned: M(1), 7.90+/-0.20; M(2), 9.04+/-0.08; M(3), 6.40+/-0.07; M(4), 7.40+/-0.04). Furthermore, particularly relevant for this investigation were tetra-amines dipitramine and AM172 for their ability to significantly differentiate M(1) and M(4) receptors. The apparent affinity values (pA:(2)) obtained for tetra-amines in functional studies using the prostatic portion of rabbit vas deferens correlated most closely with the values (pK:(i)) obtained at either native or human recombinant muscarinic M(4) receptors. This supports the view that the muscarinic receptor mediating inhibition of neurogenic contractions of rabbit vas deferens may not belong to the M(1) type but rather appears to be of the M(4) subtype.

Increased activity of the protein kinase C-delta holoenzyme in the cytoplasmic particulate fraction precedes the activation of caspases in polyomavirus-transformed pyF111 rat fibroblasts exposed to calphostin C or topoisomerase-II inhibitors.

A caspase-mediated release of the 40-kDa catalytic fragment of the delta isoform (CF-delta) of protein kinase C (PKC-delta) is involved in apoptosis, but its actual role in apoptosis development is still unknown. In an effort to understand this role, we have used polyomavirus-transformed pyF111 rat fibroblasts, which are hypersusceptible to apoptosis as they constitutively hyperexpress PKC-delta, but cannot make the antiapoptotic Bcl-2 and Bcl-X(L) proteins, while making the proapoptotic Bax protein. Calphostin C is reportedly both a specific inhibitor of PKC-delta activity (C. Keenan, N. Goode, and C. Pears, 1997, FEBS Lett. 415, 101-108) and an effective apoptogen (M. Murata et al., 1997, Cell. Mol. Life Sci. 53, 737-743). Exposure of pyF111 cells to calphostin C (75 nM) stimulated the translocation of the PKC-delta holoenzyme (holo-PKC-delta) onto the cytoplasmic particulate (CP) fraction between 15 and 45 min, which was after the release of mitochondrial cytochrome c but before the activation of cytoplasmic DEVD-specific caspases. The CF-delta fragment started accumulating only between 2 and 4 h, while apoptosis occurred mostly within 6 h. Incubating pyF111 cells with the much slower acting, apoptogenic topoisomerase-II inhibitors etoposide (VP-16) and teniposide (VM-26) also caused within 6 h a doubling of the CP-bound holo-PKC-delta-related activity but with no significant translocation of the holoenzyme to the CP fraction. Again this occurred after the release of cytochrome c but before the activation of DEVDases and the accumulation of the CF-delta. However, while calphostin C did not affect the delta-related activity in the nuclear membrane (NM) and nucleoplasmic (NP) fractions, VP-16 and VM-26 caused a prompt, large, and irreversible drop in the delta activity at the NM and a transient surge followed by a fall in the NP-associated activity. Hence, a surge of CP-anchored holo-PKC-delta activity is a common part of the signals given by various apoptogenic drugs to pyF111 cells. On the other hand, inhibition of delta-related activity, first at the NM and then in the NP fraction, is a specific feature only of the signals given by apoptogenic DNA-damaging agents.

Design, synthesis, and biological evaluation of symmetrically and unsymmetrically substituted methoctramine-related polyamines as muscular nicotinic receptor noncompetitive antagonists.

The universal template approach to drug design foresees that a polyamine can be modified in such a way to recognize any neurotransmitter receptor. Thus, hybrids of polymethylene tetraamines and philanthotoxins, exemplified by methoctramine (1) and PhTX-343 (2), respectively, were synthesized to produce novel inhibitors of muscular nicotinic acetylcholine receptors. Polyamines 3-25 were synthesized and their biological profiles were evaluated at frog rectus abdominis muscle nicotinic receptors and guinea pig left atria (M(2)) and ileum longitudinal muscle (M(3)) muscarinic acetylcholine receptors. All of the compounds, like prototypes 1 and 2, were noncompetitive antagonists of nicotinic receptors while being, like 1, competitive antagonists at muscarinic M(2) and M(3) receptor subtypes. Interestingly, polyamines bearing a low number of methylenes between the nitrogen atoms, as in 3, 6, and 7, displayed a biological profile similar to that of 2: a noncompetitive antagonism at nicotinic receptors in the 7-25 microM range while not showing any antagonism for muscarinic receptors up to 10 microM. Increasing the number of methylenes separating these nitrogen atoms in methoctramine-related tetraamines resulted in a significant improvement in potency at nicotinic receptors. The most potent tetraamine was 19, bearing a 12 methylene spacer between the nitrogen atoms, which was 12-fold and 250-fold more potent than prototypes 1 and 2, respectively. Tetraamines 9-11, bearing a rather rigid spacer between the nitrogen atoms instead of the very flexible polymethylene chain, displayed a profile similar to that of 1 at nicotinic receptors, whereas a significant decrease in potency was observed at muscarinic M(2) receptors. This finding may have relevance in understanding the mode of interaction with these receptors. Similarly, the constrained analogue 12 of methoctramine showed a decrease in potency at nicotinic and muscarinic M(2) receptors, revealing that the tricyclic system, which incorporates the 2-methoxybenzylamine moiety of 1, does not represent a good pharmacophore for activity at these sites. A most intriguing finding was the observation that the photolabile tetraamine 22 was more potent than methoctramine at nicotinic receptors and, what is more important, it inhibited a closed state of the receptor.

WB 4101-related compounds. 2. Role of the ethylene chain separating amine and phenoxy units on the affinity for alpha(1)-adrenoreceptor subtypes and 5-HT(1A) receptors.

WB 4101 (1)-related benzodioxanes were synthesized by replacing the ethylene chain separating the amine and the phenoxy units of 1 with a cyclopentanol moiety, a feature of 6, 7-dihydro-5-[[(cis-2-hydroxy-trans-3-phenoxycyclopentyl)amino]meth yl] -2-methylbenzo[b]thiophen-4(5H)-one that was reported to display an intriguing selectivity profile at alpha(1)-adrenoreceptors. This synthesis strategy led to 4 out of 16 possible stereoisomers, which were isolated in the case of (-)-3, (+)-3, (-)-4, and (+)-4 and whose absolute configuration was assigned using a chiral building block for the synthesis of (-)-3 starting from (+)-(2R)-2, 3-dihydro-1,4-benzodioxine-2-carboxylic acid ((+)-9) and (1S,2S, 5S)-2-amino-5-phenoxycyclopentan-1-ol ((+)-10). The aim of this project was to further investigate whether it is possible to differentiate between these compounds with respect to their affinity for alpha(1)-adrenoreceptor subtypes and the affinity for 5-HT(1A) receptors, as 1 binds with high affinity at both receptor systems. The biological profiles of reported compounds at alpha(1)-adrenoreceptor subtypes were assessed by functional experiments in isolated rat vas deferens (alpha(1A)), spleen (alpha(1B)), and aorta (alpha(1D)) and by binding assays in CHO and HeLa cells membranes expressing the human cloned alpha(1)-adrenoreceptor subtypes and 5-HT(1A) receptors, respectively. Furthermore, the functional activity of (-)-3, (+)-3, (-)-4, and (+)-4 toward 5-HT(1A) receptors was evaluated by determining the induced stimulation of [(35)S]GTPgammaS binding in cell membranes from HeLa cells transfected with human cloned 5-HT(1A) receptors. The configuration of the cyclopentane unit determined the affinity profile: a 1R configuration, as in (+)-3 and (-)-4, conferred higher affinity at alpha(1)-adrenoreceptors, whereas a 1S configuration, as in (-)-3 and (+)-4, produced higher affinity for 5-HT(1A) receptors. For the enantiomers (+)-4 and (-)-4 also a remarkable selectivity was achieved. Functionally, the stereoisomers displayed a similar alpha(1)-selectivity profile, that is alpha(1D) > alpha(1B) > alpha(1A), which is different from that exhibited by the reference compound 1. The epimers (-)-3 and (+)-4 proved to be agonists at the 5-HT(1A) receptors, with a potency comparable to that of 5-hydroxytryptamine.

Changes in nuclear protein kinase C-delta holoenzyme, its catalytic fragments, and its activity in polyomavirus-transformed pyF111 rat fibroblasts while proliferating and following exposure to apoptogenic topoisomerase-II inhibitors.

Protein kinase C-delta (PKC-delta) appears to be variously involved in proliferation and apoptosis. To compare the changes of this enzyme in these two processes, we have determined the levels and activities of the 79-kDa PKC-delta holoenzyme and its catalytically active 47- and 40-kDa C-terminal fragments in the nuclei of proliferating untreated polyomavirus-transformed pyF111 rat fibroblasts and pyF111 cells treated with the apoptogenic topoisomerase-II inhibitors VP-16 (etoposide), VM-26 (teniposide), and doxorubicin. PyF111 cells were chosen because they hyperexpress PKC-delta and they are hypersusceptible to apoptosis because they do not express the antiapoptotic proteins Bcl-2 and Bcl-XL. The highest PKC-delta activity in cells before they started proliferating or were exposed to one of the inhibitors was in the NM (nuclear envelope-containing) fraction, which contained the holoenzyme and both C-terminal fragments, while only the two fragments were in the nucleoplasmic (NP) fraction where they were tightly associated with chromatin. When the cells began proliferating the amounts of the PKC-delta holoenzyme and the two fragments increased in the NM and the NP fractions and the already high PKC-delta activity either increased or stayed the same in these fractions until the end of the 72-h incubation. And there was no leakage of cytochrome c from the mitochondria into the cytoplasm. VP-16 exposure caused a prompt release of cytochrome c from the mitochondria into the cytosol and at the same time triggered a sharp drop (35% by 3 h and 60% by 6 h) in the PKC-delta activity in the NM fraction without changing the actual amounts of the holoenzyme or its fragments. This prompt inactivation of PKC-delta and its fragments during the first 6 h of exposure to the drug was not due to their dephosphorylation and could not be reversed by phosphatidylserine and/or 12-O-tetradecanoylphorbol 13-acetate (TPA). Between 6 and 24 h the PKC-delta activity in the NM fraction dropped a further 20%, the kinase's activity transiently surged in the NP fraction, and cytoplasmic CPP-32-like (DEVD-specific caspase) activity increased without an increase in the proteolysis of nuclear PKC-delta or PARP. Between 24 and 72 h nuclear CPP-32-like activity increased along with a massive proteolysis of PKC-delta, an accumulation of various PKC-delta fragments, and the cleavage of PARP. But despite this proteolysis, the cells were still able to maintain or even increase the amounts of holoenzyme and 40- and 47-kDa fragments in the NM and NP fractions before dying. VM-26 and doxorubicin caused the same prompt release of cytochrome c from the mitochondria and dramatic drop of NM PKC-delta activity as did VP-16. Thus, high levels of activity of nuclear PKC-delta, particularly PKC-delta in the nuclear membrane, might have a role driving the cell cycle of pyF111 cells. On the other hand, the prompt and sustained large drop in the activity of PKC-delta at this site that precedes the onset of the caspase-mediated proteolysis of the isoform may be involved in starting and driving apoptogenesis in pyF111 fibroblasts exposed to topoisomerase-II inhibitors.