Papain-like lysosomal cysteine proteases and their inhibitors: drug discovery targets?

Papain-like lysosomal cysteine proteases are processive and digestive enzymes that are expressed in organisms from bacteria to humans. Increasing knowledge about the physiological and pathological roles of cysteine proteases is bringing them into the focus of drug discovery research. These proteases have rather short active-site clefts, comprising three well defined substrate-binding subsites (S2, S1 and S1') and additional broad binding areas (S4, S3, S2' and S3'). The geometry of the active site distinguishes cysteine proteases from other protease classes, such as serine and aspartic proteases, which have six and eight substrate-binding sites respectively. Exopeptidases (cathepsins B, C, H and X), in contrast with endopeptidases (such as cathepsins L, S, V and F), possess structural features that facilitate the binding of N- and C-terminal groups of substrates into the active-site cleft. Other than a clear preference for free chain termini in the case of exopeptidases, the substrate-binding sites exhibit no strict specificities. Instead, their subsite preferences arise more from the specific exclusion of substrate types. This presents a challenge for the design of inhibitors to target a specific cathepsin: only the cumulative effect of an assembly of inhibitor fragments will bring the desired result.     

Microbial conversion of pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione acetates by Nocardioides simplex VKM Ac-2033D

The conversion of pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione 21-acetate (I) and 17,21-diacetate (VI) by Nocardioides simplex VKM Ac-2033D was studied. The major metabolites formed from I were identified as pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II) and pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione (IV). Pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione (III) and pregna-1,4,9(11)-triene-17alpha,20beta,21-triol-3-one (V) were formed in minorities. Biotransformation products formed from VI were pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17,21-diacetate (VII), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione (IV), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17-acetate (VIII), pregna-1,4,9(11)-triene-17alpha,20beta,21-triol-3-one (V). The conversion pathways were proposed including 1(2)-dehydrogenation, deacetylation, 20beta-reduction and non-enzymatic migration of acyl group from position 17 to 21. The conditions providing predominant accumulation of pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II) from I and pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17-acetate (VIII) from VI in a short-term biotransformation were determined.     

The intramural innervation of the rabbit upper urinary tract

The role of the autonomic innervation of the upper urinary tract for pyeloureteral motility is not completely understood. It is still debatable if the autonomic nervous system might play a modulating role on the ureteral peristalsis. The aim of this study was to investigate the distribution and regional variation of the intramural innervation using whole-mount preparations of the rabbit upper urinary tract. Whole-mount preparation was performed at upper urinary tracts of healthy rabbits. Immunohistochemistry was employed using Neurofilament (NF), Tyrosine Hydroxylase (TH), Choline Acetyltransferase (ChAT) and Substance P (SP) antibodies. NADPH-diaphorase and Acetylcholinesterase (AChE) histochemistry was carried out at the specimens. The stains were evaluated using brightfield, fluorescence and laser confocal microscopy. NF-, TH-, ChAT- and SP-immunoreactive (-IR) nerves formed distinct neuronal plexuses at the submucosal and muscle layers. Perivascular TH-, ChAT- and SP-IR fibres were demonstrated. AChE positive nerves were revealed in all layers, but only moderate NADPH-diaphorase positive innervation was found. Renal pelvis, upper and lower ureter showed enriched intrinsic innervation. Ganglia were found at the ureteropelvic border and the distal ureter. Whole-mount preparation technique revealed detailed informations about morphology and regional variation of the intramural innervation of the rabbit upper urinary tract.     

Spike generating dynamics and the conditions for spike-time precision in cortical neurons

Temporal precision of spiking response in cortical neurons has been a subject of intense debate. Using a canonical model of spike generation, we explore the conditions for precise and reliable spike timing in the presence of Gaussian white noise. In agreement with previous results we find that constant stimuli lead to imprecise timing, while aperiodic stimuli yield precise spike timing. Under constant stimulus the neuron is a noise perturbed oscillator, the spike times follow renewal statistics and are imprecise. Under an aperiodic stimulus sequence, the neuron acts as a threshold element; the firing times are precisely determined by the dynamics of the stimulus. We further study the dependence of spike-time precision on the input stimulus frequency and find a non-linear tuning whose width can be related to the locking modes of the neuron. We conclude that viewing the neuron as a non-linear oscillator is the key for understanding spike-time precision.     

Remarkable interkingdom conservation of intron positions and massive,lineage-specific intron loss and gain in eukaryotic evolution

Sequencing of eukaryotic genomes allows one to address major evolutionary problems, such as the evolution of gene structure. We compared the intron positions in 684 orthologous gene sets from 8 complete genomes of animals, plants, fungi, and protists and constructed parsimonious scenarios of evolution of the exon-intron structure for the respective genes. Approximately one-third of the introns in the malaria parasite Plasmodium falciparum are shared with at least one crown group eukaryote; this number indicates that these introns have been conserved through >1.5 billion years of evolution that separate Plasmodium from the crown group. Paradoxically, humans share many more introns with the plant Arabidopsis thaliana than with the fly or nematode. The inferred evolutionary scenario holds that the common ancestor of Plasmodium and the crown group and, especially, the common ancestor of animals, plants, and fungi had numerous introns. Most of these ancestral introns, which are retained in the genomes of vertebrates and plants, have been lost in fungi, nematodes, arthropods, and probably Plasmodium. In addition, numerous introns have been inserted into vertebrate and plant genes, whereas, in other lineages, intron gain was much less prominent.     

Subzero nonfreezing cryopresevation of rat hearts using antifreeze protein I and antifreeze protein III

The purpose of the present study was to evaluate whether AFPs protect the heart from freezing and improve survival and viability in subzero cryopreservation. Hearts were subject to 5 preservation protocols; University of Wisconsin solution (UW) at 4 degrees C, UW at -1.3 degrees C without nucleation, UW at -1.3 degrees C with nucleation, UW AFP I (15 mg/cm(3)) at -1.3 degrees C with nucleation, and in UW AFP III (15 mg/cm(3)) at -1.3 degrees C with nucleation. Hearts were preserved for 24, 28, and 32 h, rewarmed and connected to the working isolated perfusion system. Data [heart rate (HR), coronary flow (CF), and developed pressure (dP)] was collected 30 and 60 min after reperfusion. Hearts preserved at -1.3 degrees C without AFPs froze, while hearts preserved with AFP did not freeze when nucleation was initiated and survived. Survival and dP of hearts preserved for 24h at -1.3 degrees C using AFP III was better than those preserved at 4 degrees C, (dP; 1.4 vs. 0.8, p<0.05). Four of six hearts and six of six hearts died when preserved at 4 degrees C for 28 and 32 h, respectively, all of the hearts that were preserved at -1.3 degrees C with or without AFPs survived after 28 h (n=18) and 32 h (n=18). CF was higher in UW -1.3 degrees C group without attempted nucleation than in AFP I and AFP III groups after 28 and 32 h (3.4 vs. 1.7, p<0.05, and 3.4 vs. 1.7, p<0.05, respectively). In conclusion, AFPs were found to protect the heart from freezing and improve survival and dP (AFP III) in prolonged subzero preservation.     

Some anthropologic factors of performance in rhythmic gymnastics novices

The aim of the study was to determine motor and morphological factors, and to assess their impact on specific motor skill performance in rhythmic gymnastics (RG). Experimental training process aimed at learning and improving basic movement structures of rhythmic gymnastics was performed for nine months in a sample of 50 female rhythmic gymnastics novices (mean age 7.1 +/- 0.3 years). Seven dimensions in total were isolated by factorial analysis of 13 motor, 11 morphological, and 20 specific rhythmic gymnastics tests. The factors of flexibility (Beta = 0.26; p < 0.05), explosive strength (Beta = 0.25; p < 0.05) and adipose voluminosity (Beta = -0.42; p < 0.001) explains 41% of the success in performing RG basic body elements--jumps, rotations, balance and flexibility (R = 0.64), while the frequency of movement (Beta = 0.44; p < 0.001) and non-adipose voluminosity (Beta = 0.26; p < 0.05) explains 26% of RG-specific manipulations with the apparatus--club, ribbon and ball wrist manipulation (R = 0.52; p < 0.01). According to study results, the RG-training process intended for rhythmic gymnastics novices should be programmed, with preset objectives for the development of flexibility and explosive strength, speed and peripheral joint strength and adipose tissue reduction.     

Quantitative analysis of signaling networks

The response of biological cells to environmental change is coordinated by protein-based signaling networks. These networks are to be found in both prokaryotes and eukaryotes. In eukaryotes, the signaling networks can be highly complex, some networks comprising of 60 or more proteins. The fundamental motif that has been found in all signaling networks is the protein phosphorylation/dephosphorylation cycle--the cascade cycle. At this time, the computational function of many of the signaling networks is poorly understood. However, it is clear that it is possible to construct a huge variety of control and computational circuits, both analog and digital from combinations of the cascade cycle. In this review, we will summarize the great versatility of the simple cascade cycle as a computational unit and towards the end give two examples, one prokaryotic chemotaxis circuit and the other, the eukaryotic MAPK cascade.