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.     

Carisoprodol abuse: a report from India

Carisoprodol, a centrally acting muscle relaxant, has recently been noticed to be abused. A series of 16 cases with carisoprodol abuse or dependence is described. Carisoprodol was started by the majority of patients as a substitute for opiates, although its independent distinct effects, similar to the features of hypomania, were recognized and described by most users. The drug is currently available freely over the counter and is a much cheaper substitute for the legally prohibited "harder" drugs. Unless awareness spreads and cautionary measures are taken, carisoprodol abuse might become a great menace in the near future.     

The effects of lipase‐encapsulating carriers on the accelerated ripening of Kashar cheese

In this study, lipase enzymes were encapsulated in κ‐carragenan, gellan and sodium alginate using emulsion and extrusion techniques and were then added to cheese milk together with rennet. The effects of the encapsulating material and ripening period on the chemical, textural and sensory characteristics of Kashar cheese were investigated. The study demonstrated that sodium alginate, gellan and κ‐carrageenan could successfully be used as lipase carrier systems to accelerate the fat breakdown process during the ripening of Kashar cheese. Those samples treated with κ‐carrageenan capsules showed the highest rate of lipolysis and proteolysis compared to those treated with the other capsules.     

Synthesis and characterization of lanthanum strontium manganite

La_0.85Sr_0.15MnO₃ (LSM) powder has been prepared by co-precipitation. Phase evolution studies by DTA, TGA and XRD indicated initiation of LSM formation above 750 °C. Densification behaviour of LSM powder with and without pore former was different. Sintered LSM was characterized for electrical conductivity, thermal expansion and microstructural development.     

Nucleation sequence on the cation exchange process between Y0.95Eu0.05PO4 and CePO4 nanorods

Nanorods of Y0.95Eu0.05PO4@CePO4 (Y0.95Eu0.05PO4 phase was nucleated first and then a CePO4 phase was nucleated) and CePO4@Y0.95Eu0.05PO4 (CePO4 phase was nucleated first and then Y0.95Eu0.05PO4 phase was nucleated) were prepared at a relatively low temperature of 140 °C in ethylene glycol medium. Based on XRD, TEM and Raman studies it has been inferred that Y0.95Eu0.05PO4@CePO4 sample consists of a mixture of bigger (length around 800-1000 nm and width around of 80-100 nm) and smaller (length around 70-100 nm and width around 10-20 nm) nanorods, having monoclinic CePO4 and tetragonal YPO4 structure, whereas CePO4@Y0.95Eu0.05PO4 sample consists of mainly small nanorods having a single phase CePO4 structure. From the detailed luminescence studies it has been established that there exists significant incorporation of Y3+/Eu3+ ions in the CePO4 phase in CePO4@Y0.95Eu0.5PO4 sample. This has been attributed to the cation exchange taking place between Ce3+ ions in CePO4 host and Eu3+ and Y3+ ions in solution during the synthesis stage. Unlike this, such an exchange is not possible for Y0.95Eu0.05PO4@CePO4 sample synthesized under identical conditions due to the higher solubility product (Ksp) value of YPO4 compared to CePO4. Incorporation of Eu3+ in the CePO4 lattice of CePO4@Y0.95Eu0.5PO4 sample is confirmed by the significant reduction in the lifetime of 5D0 level of Eu3+ and the luminescence intensity from Eu3+, arising due to the electron transfer between the Ce3+/Ce4+ and Eu3+/Eu2+ species. These results are further supported by the non-radiative decay rates and quantum yields calculated from the emission spectrum.     

Thymus size in infants from birth until 24 months of age evaluated by ultrasound. A longitudinal prediction model for the thymic index

To determine whether an absence of leukocytes in semen and urine predicts an absence of Chlamydia trachomatis in asymptomatic infertile men, chlamydial DNA was detected in subjects' semen and urine by ligase chain reaction (LCR). Ninety-eight infertile men were studied, including 39 cases of oligozoospermia, 19 of azoospermia, 16 of asthenozoospermia, and 24 of normozoospermia. None of the subjects had pyospermia or pyuria. C. trachomatis was detected by LCR. Antichlamydial and antisperm antibody were also measured. C. trachomatis was detected by LCR in the semen of only 1 of 98 patients (1.02%), but not in the urine samples. In C. trachomatis-positive patients LCR, IgG, and IgA levels were higher than normal. No antisperm antibody was detected. Even if leukocytes are not observed in the semen and urine of asymptomatic infertile men, the presence of C. trachomatis in semen specimens is rarely observed. Therefore, it should be noted that the presence of C. trachomatis in such cases is addressed in the context of artificial insemination and other assisted reproductive technologies.     

The impact of primary and modular nursing delivery systems on perceptions of caring behavior

BACKGROUND: The somatostatin analogue octreotide impairs intestinal regeneration and the adaptive response to intestinal resection by inhibition of enterocyte migration and proliferation and increased apoptosis. Epidermal growth factor (EGF) stimulates regeneration and adaptation by increasing proliferation and reducing apoptosis. The aim of this study was to determine the effect of EGF on octreotide-induced enterocyte apoptosis. METHODS: Twenty-four rabbits underwent patch enteroplasty in the distal ileum to stimulate the mucosa. There were four study groups: octreotide 250 microgram/kg/day, EGF 40 microgram/kg/day, EGF plus octreotide, and control. Normal ileal mucosa adjacent to the patch was evaluated at 7 days for villus height, crypt depth, crypt cell production rate (CCPR), and in situ end labeling of DNA fragmentation. RESULTS: Octreotide alone increased apoptosis compared with controls at the villus tip (40 +/- 7% vs 18 +/- 7%, P < 0.05), lateral villus (9 +/- 2% vs 3 +/- 2%, P < 0.05), and crypt (15 +/- 3% vs 10 +/- 3%, P < 0. 05). EGF decreased apoptosis in the crypt (2 +/- 1%) and villus (6 +/- 1% villus tip and 1 +/- 1% lateral villus, P < 0.05) compartments. EGF inhibited octreotide-induced apoptosis in the crypt (5 +/- 2%) but not the villus (31 +/- 5% villus tip and 6 +/- 2% lateral villus, P < 0.05). Mean DNA fragmentation was significantly greater in octreotide-treated animals (P < 0.05). The octreotide-treated animals had reduced crypt depth and villus height but normal CCPR compared with controls. EGF increased CCPR and crypt depth compared with controls. Combining EGF and octreotide resulted in crypt depth and CCPR similar to those of controls but reduced villus height. CONCLUSIONS: EGF inhibits octreotide-induced apoptosis. This effect is greater in crypt than in villus enterocytes. Octreotide appears to have both direct and indirect effects on enterocyte apoptosis.     

Defective calcium binding to fibrillin-1: consequence of an N2144S change for fibrillin-1 structure and function

Fibrillin-1 is a major structural component of 10-12 nm connective tissue microfibrils and has a modular organisation that includes 43 calcium binding epidermal growth factor-like (cbEGF) domains and seven transforming growth factor beta-binding protein-like (TB) domains. Mutations in the fibrillin-1 (FBN1) gene cause the Marfan syndrome (MFS) and related connective tissue disorders. We have previously investigated an N2144S change, identified in a MFS patient, which removes one of the key calcium binding ligands within cbEGF domain 32. In this study the structural consequences of the N2144S amino acid change for the folding and calcium binding properties of mutant and wild-type TB6-cbEGF32 and cbEGF32-33 domain pairs have been analysed by nuclear magnetic resonance. The presence of an N2144S substitution does not alter the native fold of either the TB6 domain, or cbEGF domains 32 and 33. Comparison of calcium dissociation constants measured for the wild-type and mutant pairs shows that: (i) the affinity of cbEGF32 is weakly enhanced by N-terminal linkage of TB6 relative to cbEGF32 in isolation; (ii) the affinity of cbEGF32 is approximately ninefold decreased by the N2144S substitution in the TB-cbEGF pair; and (iii) reduced affinity of cbEGF32 does not result in lower affinity of cbEGF33 for calcium. Together, these data suggest that the TB6-cbEGF32 linkage is flexible and the structural effect of the mutation is localised to the interdomain linkage. We have also investigated the effect of defective calcium binding to cbEGF32 on fibrillin-1 produced by N2144S MFS fibroblasts. 35S-pulse-chase analysis shows that the N2144S substitution does not detectably affect fibrillin-1 biosynthesis, rate of secretion or processing. Deposition of reducible fibrillin-1 into the extracellular matrix was also unaffected. The implications of these results for the assembly and properties of the microfibril are discussed.     

Cracking the auditory genetic code: nonsyndromic hereditary hearing impairment

Vascular anomalies of the head and neck are common lesions of childhood. The vascular anomalies can be divided into hemangiomas and vascular malformations. Each of these lesions has a characteristic imaging appearance. Correctly classifying the anomaly is essential in directing the treatment of these lesions.     

Paramagnetic liposomes as MRI contrast agents: influence of liposomal physicochemical properties on the in vitro relaxivity

Because of the possible application of tea in the prevention of oral and esophageal cancers, the salivary levels of tea catechins were determined in six human volunteers after drinking tea. Saliva samples were collected after thoroughly rinsing the mouth with water. After drinking green tea preparations equivalent to two to three cups of tea, peak saliva levels of (-)-epigallocatechin (EGC; 11.7-43.9 microg/ml), EGC-3-gallate (EGCG; 4.8-22 microg/ml), and (-)-epicatechin (EC; 1.8-7.5 microg/ml) were observed after a few minutes. These levels were 2 orders of magnitude higher than those in the plasma. The elimination half-life (t(1/2)) of the salivary catechins was 10-20 min, much shorter than that of the plasma. Holding a tea solution in the mouth for a few minutes without swallowing produced even higher salivary catechin levels, but taking tea solids in capsules resulted in no detectable salivary catechin level. Holding an EGCG solution in the mouth resulted in EGCG and EGC in the saliva and, subsequently, EGC in the urine. The results suggest that EGCG was converted to EGC in the oral cavity, and both catechins were absorbed through the oral mucosa. A catechin esterase activity that converts EGCG to EGC was found in the saliva. The enzyme was likely of human origin, but the activity was not inhibited by common human esterase inhibitor. The present results suggest that slowly drinking tea is a very effective way of delivering rather high concentrations of catechins to the oral cavity and then the esophagus.