Phenobarbital enhances 2',5'-oligoadenylate synthesis in rat liver nuclei

Treatment of rats with phenobarbital for three days greatly increases the activity of 2,5 oligoadenylate synthetase in liver nuclei. Analysis of 2',5'-oligoadenylates synthesized in vitro showed that nuclei from both phenobarbital-treated and control rats synthesized 2',5'-oligoadenylates ranging from di- to hexamers. However, nuclei from drug treated rats showed a two fold increase in trimer and tetramer synthesis and a three-four fold increase in longer chained oligoadenylates. There was no change in the nuclear 2'-phosphodiesterase activity as the result of phenobarbital treatment, This activity remained low in nuclei from either the treated or the control rats. To our knowledge, this is the first report on phenobarbital affecting the liver 2',5'-oligoadenylate system.     

Comparative analysis of the CD19+ and CD138+ cell antibody repertoires in the cerebrospinal fluid of patients with multiple sclerosis

Increased amounts of intrathecally synthesized IgG and oligoclonal bands have long been recognized as a hallmark of multiple sclerosis (MS). B cells and plasma cells are components of the inflammatory infiltrates in both active and chronic MS lesions, and increased numbers of these cells are present in MS cerebrospinal fluid (CSF). Single-cell RT-PCR was used to analyze both the CD19+ B cell and CD138+ plasma cell populations in CSF of two patients with clinically definite MS and of one MS patient whose CSF was obtained after a clinically isolated syndrome, but before the second episode. Sequence analysis of amplified IgG V region sequences identified the rearranged germline segments, extent of somatic mutation, and clonal relationships within and between the two cell populations in the three MS patients. Expanded B cell and plasma cell clones were detected in each MS CSF and in all three patients the CD138+ IgG repertoire was more restricted. However, little if any significant sequence overlap was observed between the CD19+ and CD138+ repertoires of each donor. Detection of plasma cell clones by single-cell PCR will facilitate the in vitro production of recombinant Abs useful in identifying disease-relevant Ags.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Sulphated tyrosines mediate association of chemokines and Plasmodium vivax Duffy binding protein with the Duffy antigen/receptor for chemokines (DARC)

Plasmodium vivax is one of four Plasmodium species that cause human malaria. P. vivax and a related simian malaria parasite, Plasmodium knowlesi, invade erythrocytes by binding the Duffy antigen/receptor for chemokines (DARC) through their respective Duffy binding proteins. Here we show that tyrosines 30 and 41 of DARC are modified by addition of sulphate groups, and that the sulphated tyrosine 41 is essential for association of the Duffy binding proteins of P. vivax (PvDBP) and P. knowlesi (PkDaBP) with DARC-expressing cells. These sulphated tyrosines also participate in the association of DARC with each of its four known chemokine ligands. Alteration of tyrosine 41 to phenylalanine interferes with MCP-1, RANTES and MGSA association with DARC, but not with that of IL8. In contrast, alteration of tyrosine 30 to phenylalanine interferes with the association of IL8 with DARC. A soluble sulphated amino-terminal domain of DARC, but not one modified to phenylalanine at residue 41, can be used to block the association of PvDBP and PkDaBP with red blood cells, with an IC50 of approximately 5 nM. These data are consistent with a role for tyrosine sulphation in the association of many or most chemokines with their receptors, and identify a key molecular determinant of erythrocyte invasion by P. vivax.     

Cryptosporidium andersoni n. sp. (Apicomplexa: Cryptosporiidae) from cattle, Bos taurus

A new species of Cryptosporidium is described from the feces of domestic cattle, Bos taurus. Oocysts are structurally similar to those of Cryptosporidium muris described from mice but are larger than those of Cryptosporidium parvum. Oocysts of the new species are ellipsoidal, lack sporocysts, and measure 7.4 x 5.5 microm (range, 6.0-8.1 by 5.0-6.5 microm). The length to width ratio is 1.35 (range, 1.07-1.50). The colorless oocyst wall is < 1 microm thick, lacks a micropyle, and possesses a longitudinal suture at one pole. A polar granule is absent, whereas an oocyst residuum is present. Oocysts were passed fully sporulated and are not infectious to outbred, inbred immunocompetent or immunodeficient mice, chickens or goats. Recent molecular analyses of the rDNA 18S and ITS1 regions and heat-shock protein 70 (HSP-70) genes demonstrate this species to be distinct from C. muris infecting rodents. Based on transmission studies and molecular data, we consider the large form of Cryptosporidium infecting the abomasum of cattle to be a new species and have proposed the name Cryptosporidium andersoni n. sp. for this parasite.     

Comparison of HIV-1 nef and gag Variations and Host HLA Characteristics as Determinants of Disease Progression among HIV-1 Vertically Infected Kenyan Children

Objectives

Disease progression varies among HIV-1-infected individuals. The present study aimed to explore possible viral and host factors affecting disease progression in HIV-1-infected children.

Methods

Since 2000, 102 HIV-1 vertically-infected children have been followed-up in Kenya. Here we studied 29 children (15 male/14 female) who started antiretroviral treatment at <5 years of age (rapid progressors; RP), and 32 (17 male/15 female) who started at >10 years of age (slow progressors; SP). Sequence variations in the HIV-1 gag and nef genes and the HLA class I-related epitopes were compared between the two groups.

Results

Based on nef sequences, HIV-1 subtypes A1/D were detected in 62.5%/12.5% of RP and 66.7%/20% of SP, with no significant difference in subtype distribution between groups (p = 0.8). In the ten Nef functional domains, only the PxxP₃ region showed significantly greater variation in RP (33.3%) than SP (7.7%, p = 0.048). Gag sequences did not significantly differ between groups. The reportedly protective HLA-A alleles, A*74:01, A*32:01 and A*26, were more commonly observed in SP (50.0%) than RP (11.1%, p = 0.010), whereas the reportedly disease-susceptible HLA-B*45:01 was more common in RP (33.3%) than SP (7.4%, p = 0.045). Compared to RP, SP showed a significantly higher median number of predicted HLA-B-related 12-mer epitopes in Nef (3 vs. 2, p = 0.037), HLA-B-related 11-mer epitopes in Gag (2 vs. 1, p = 0.029), and HLA-A-related 9-mer epitopes in Gag (4 vs. 1, p = 0.051). SP also had fewer HLA-C-related epitopes in Nef (median 4 vs. 5, p = 0.046) and HLA-C-related 11-mer epitopes in Gag (median 1 vs. 1.5, p = 0.044) than RP.

Conclusions

Compared to rapid progressors, slow progressors had more protective HLA-A alleles and more HLA-B-related epitopes in both the Nef and Gag proteins. These results suggest that the host factor HLA plays a stronger role in disease progression than the Nef and Gag sequence variations in HIV-1-infected Kenyan children.     

Purification and characterization of rat liver microsomal beta-glucuronidase.

Beta-Glucuronidase (EC 3.2.1.31) has been isolated from rat-liver microsomes by a novel chromatographic method employing antibody to rat preputial gland beta-glucuronidase coupled to Sepharose. The purified enzyme, homogeneous by several methods, was purified some 1700-fold. The microsomal beta-glucuronidase has been characterized with respect to catalysis, stability, and molecular weight. The purified enzyme is a tetramer of 290 000 daltons. Comparative studies with lysosomal beta-glucuronidase indicate that while these two enzymes are electrophoretically distinct, they are catalytically and immunologically identical and have indistinguishable molecular dimensions. The results suggest that microsomal and lysosomal beta-glucuronidase are charge isomers.     

Activation Domain-dependent Degradation of Somatic Wee1 Kinase

Cell cycle progression is dependent upon coordinate regulation of kinase and proteolytic pathways. Inhibitors of cell cycle transitions are degraded to allow progression into the subsequent cell cycle phase. For example, the tyrosine kinase and Cdk1 inhibitor Wee1 is degraded during G₂ and mitosis to allow mitotic progression. Previous studies suggested that the N terminus of Wee1 directs Wee1 destruction. Using a chemical mutagenesis strategy, we report that multiple regions of Wee1 control its destruction. Most notably, we find that the activation domain of the Wee1 kinase is also required for its degradation. Mutations in this domain inhibit Wee1 degradation in somatic cell extracts and in cells without affecting the overall Wee1 structure or kinase activity. More broadly, these findings suggest that kinase activation domains may be previously unappreciated sites of recognition by the ubiquitin proteasome pathway.