Novel azapeptide inhibitors of cathepsins B and K. Structural background to increased specificity for cathepsin B

Abstract: We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor–enzyme complex, K_i, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z‐Arg‐Leu‐His‐Agly‐Ile‐Val‐OMe ( 7 ) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7 . We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K.     

Synthesis and anti-tuberculous activity of diesters based on isosteviol and dicarboxylic acids

Diesters based on isosteviol and dicarboxylic acids were synthesized and tested for antituberculous activity. Isosteviol and some of its derivatives exhibit appreciable tuberculostatic properties in vitro, the activity being dependent on the length of the polymethylene spacer connecting two ent-beyeran fragments. The mechanism of the antituberculous action of isosteviol derivatives are discussed. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 9, pp. 12–13, September, 2006.     

Evaluation of tissue response to MTA and Portland cement with iodoform.

OBJECTIVE: The aim of this study was to evaluate the biocompatibility of Portland cement with the addition of iodoform, compared to MTA (ProRoot). STUDY DESIGN: Eighteen Wistar albino rats were divided into 3 groups of 6 animals each. Polyethylene tubes were filled either with freshly mixed MTA or Portland cement mixed with iodoform (20% wt/wt) and implanted subcutaneously. An empty tube served as control. After 7, 30, or 60 days, the implants together with the surrounding tissues were removed in blocks. Sections were evaluated for the presence and thickness of a fibrous capsule, presence of granulation tissue, and the severity of inflammatory response. Data were submitted to nonparametric statistical analysis with individual comparisons between groups at a significance level of P < 0.05. RESULTS: There were no differences between inflammatory responses at 7 and 30 days. After 60 days from surgical removal, there was significantly more tissue reaction to the MTA and Portland cement compared to the control group. CONCLUSION: There were no significant differences regarding inflammatory responses between MTA and Portland cement with iodoform after 7, 30, or 60 days. After 60 days, the fibrous capsule around the Portland cement appeared more organized than tissue surrounding MTA implants. After 60 days, there was still a significantly increased tissue reaction to the 2 cements compared to the empty polyethylene tubes.     

Mycobacterium caprae in cattle and humans in Croatia.

SETTING: This paper describes an outbreak of human and related bovine tuberculosis (TB) caused by Mycobacterium caprae in Croatia. A 13-year-old boy clinically presented enlargement of cervical lymph node with consecutive isolation of M. caprae. His 7-year-old sister, who had no clinical signs of disease, hyper-reacted to the purified protein derivative (PPD) test (>25 mm) and peribronchial infiltration was found by radiology. The children came from a family that ran a small-sized cattle dairy farm. DESIGN: All cattle on the farm were subjected to cutaneous TB testing: six of the 14 reacted positive, while three were suspicious. The entire herd was slaughtered, their carcasses examined and collected material subjected to pertinent diagnostic procedures. RESULTS: Gross examination findings consistent with TB were observed in the PPD-positive cows. Mycobacteria isolated from the boy and cattle were identified by classical and molecular methods, confirming M. caprae as the causative agent. CONCLUSION: Although not bacteriologically proven, consumption of raw milk or non-pasteurised milk products from infected dairy cattle was suspected as the source of infection in humans. Our findings confirm the domination of M. caprae among cattle in Croatia and represent the first evidence of M. caprae infection in humans in Croatia.     

Effect of chronic exposure to low doses of ionized radiation on embryonal development of the Japanese quail

Experiments on Japanese quail embryogenesis on a background of chronic exposure to gamma- and neutron doses comparable with the doses of ionized radiation inside the orbital space stations Mir and ISS, and exploration vehicles gave evidence that permanent absorption of low gamma-doses (0,15 cgy/d) did not impact development of the Japanese quail embryos. On the contrary, the neutron dose of 200 microgy/d imparted by the neutron flux of 30 particles/cm2s was hazardous to embryos as it caused morphological disorders in 12% of embryos.     

Distribution of tyrosine-hydroxylase (TH)-immunoreactive neurons in the diencephalon of the pigeon (Columba livia domestica)

The distribution of tyrosine-hydroxylase (TH)-immunoreactive cell bodies and fibers in the diencephalon has been investigated with immunohistological techniques in the pigeon. The results suggest that TH is present in a number of morphologically distinct neuronal systems. Preoptic and hypothalamic TH neurons were subdivided into a medial periventricular and a lateral group. The medial group starts with a rostral collection of small cells in the preoptic region. A significantly larger collection of TH neurons occupies the paraventricular nucleus (PVN) (stratum cellulare internum) and mainly consists of large multipolar cells. Further caudally, the main concentration of cells is in the hypothalamic posteromedial and the periventricular regions of the tuberoinfundibular (arcuate) nucleus. No TH neuron was found in the ventral and lateral parts of the tuberoinfundibular region, suggesting that the prominent tuberoinfundibular dopaminergic system described in mammals is absent in the pigeon. This further substantiated by the relative scarcity of TH immunoreactive fibers and varicosities in the neurohemal zone of the median eminence (ME). The caudalmost components of the medial group appear to be continuous with the large population of TH neurons distributed in the midline of the mesencephalon. Tyrosine-hydroxylase-immunopositive cells have not been found in the paraventricular organ. The lateral group consists of TH neurons loosely arranged in the lateral hypothalamus, including regions of the supraoptic nucleus and hypothalamic posterolateral nucleus. Tyrosine-hydroxylase containing neurons vary widely in size, shape, and dendritic arborization in each diencephalic region. However, it is possible to distinguish two main cell types. Small bipolar neurons with two simple arborizing dendrites were concentrated in the medial periventricular system. The second type of cell is large, multipolar with four to five branching dendrites. This latter cell type occurs mainly in the lateral system and in the PVN. Major fiber bundles containing TH immunoreactivity were identified in the lateral and periventricular hypothalamus. The paraventricular organ and the organum vasculosum laminae terminalis contained the densest arborization of fibers and varicosities. In the ME, dense innervation was found in the subependymal layer. Dense arborizations of TH positive fibers and varicosities were located in the septal nuclei and the paleostriatum augmentatum.     

Obturation of root canals using the single cone gutta-percha technique and dentinal bonding agents

Summary. The quality of the apical seal using the single cone gutta-percha obturation technique with four different dentinal bonding agents was assessed by measuring the linear penetration of methylene blue dye. No leakage was measurable in 75 per cent of the canals sealed with Scotchbond, 70 per cent of canals sealed with Restodent, 60 per cent of canals sealed with Dentin-Adhesit, and in 30 per cent of canals sealed with GLUMA. The mean linear dye penetration in canals sealed with these agents was 0.32, 1.95, 0.57 and 2.41mm, respectively. There was no statistically significant difference between the single cone gutta-percha technique and the laterally condensed gutta-percha technique when Scotchbond was used as sealer ( P > 0.01).