Prevention of antibiotic-associated metabolic syndrome in mice by intestinal alkaline phosphatase.

AIMS: To examine whether co-administration of intestinal alkaline phosphatase (IAP) with antibiotics early in life may have a preventive role against metabolic syndrome (MetS) in mice. METHODS: A total of 50 mice were allocated to four treatment groups after weaning. Mice were treated with azithromycin (AZT) ± IAP, or with no AZT ± IAP, for three intermittent 7-day cycles. After the last treatment course, the mice were administered a regular chow diet for 5 weeks and subsequently a high-fat diet for 5 weeks. Body weight, food intake, water intake, serum lipids, glucose levels and liver lipids were compared. 16S rRNA gene pyrosequencing was used to determine the differences in microbiome composition. RESULTS: Exposure to AZT early in life rendered mice susceptible to MetS in adulthood. Co-administration of IAP with AZT completely prevented this susceptibility by decreasing total body weight, serum lipids, glucose levels and liver lipids to the levels of control mice. These effects of IAP probably occur as a result of changes in the composition of specific bacterial taxa at the genus and species levels (e.g. members of Anaeroplasma and Parabacteroides). CONCLUSIONS: Co-administration of IAP with AZT early in life prevents mice from susceptibility to the later development of MetS. This effect is associated with alterations in the composition of the gut microbiota. IAP may represent a novel treatment against MetS in humans.

Intestinal alkaline phosphatase preserves the normal homeostasis of gut microbiota.

BACKGROUND AND AIMS: The intestinal microbiota plays a critical role in maintaining human health; however, the mechanisms governing the normal homeostatic number and composition of these microbes are largely unknown. Previously it was shown that intestinal alkaline phosphatase (IAP), a small intestinal brush border enzyme, functions as a gut mucosal defence factor limiting the translocation of gut bacteria to mesenteric lymph nodes. In this study the role of IAP in the preservation of the normal homeostasis of the gut microbiota was investigated. METHODS: Bacterial culture was performed in aerobic and anaerobic conditions to quantify the number of bacteria in the stools of wild-type (WT) and IAP knockout (IAP-KO) C57BL/6 mice. Terminal restriction fragment length polymorphism, phylogenetic analyses and quantitative real-time PCR of subphylum-specific bacterial 16S rRNA genes were used to determine the compositional profiles of microbiotas. Oral supplementation of calf IAP (cIAP) was used to determine its effects on the recovery of commensal gut microbiota after antibiotic treatment and also on the colonisation of pathogenic bacteria. RESULTS: IAP-KO mice had dramatically fewer and also different types of aerobic and anaerobic microbes in their stools compared with WT mice. Oral supplementation of IAP favoured the growth of commensal bacteria, enhanced restoration of gut microbiota lost due to antibiotic treatment and inhibited the growth of a pathogenic bacterium (Salmonella typhimurium). CONCLUSIONS: IAP is involved in the maintenance of normal gut microbial homeostasis and may have therapeutic potential against dysbiosis and pathogenic infections.

[Changes in epidemiological pattern of methicillin-resistant Staphylococcus aureus infections in a tertiary hospital. Experience of 5 years]. / Cambios en los patrones epidemiológicos de la infección por Staphylococcus aureus resistente a la meticilina en un hospital de tercer nivel. Experiencia de 5 años.

OBJECTIVE: To describe the demographic pattern and tendency of the infections by MRSA between 1992 and 1997. DESIGN AND METHODS: Descriptive study of the infections by MRSA in a tertiary-care hospital. RESULTS: 267 MRSA infections, 131 infections were included within 58 buds and 136 cases isolated form. The more affected services were Internal Medicine, Urology, Neurology, Vascular surgery and intensive care unit. A tendency was observed to the increase in > 65 years cases and in medical services. CONCLUSIONS: The increase of elderly cases in medical services and > 65 years carriers in their nose could translate the existent situation in the community.

Irreversible inhibition of epidermal growth factor receptor tyrosine kinase with in vivo activity by N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide (CL-387,785).

It has been shown previously that 4-anilino quinazolines compete with the ability of ATP to bind the epidermal growth factor receptor (EGF-R), inhibit EGF-stimulated autophosphorylation of tyrosine residues in EGF-R, and block EGF-mediated growth. Since millimolar concentrations of ATP in cells could reduce the efficacy of 4-anilino quinazolines in cells and the activity of these compounds would not be sustained once they were removed from the body, we reasoned that irreversible inhibitors of EGF-R might improve the activity of this series of compounds in animals. Molecular modeling of the EGF-R kinase domain was used to design irreversible inhibitors. We herein describe one such inhibitor: N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]2-butynamide, known as CL-387,785. This compound covalently bound to EGF-R. It also specifically inhibited kinase activity of the protein (IC50 = 370+/-120 pM), blocked EGF-stimulated autophosphorylation of the receptor in cells (ic50 approximately 5 nM), inhibited cell proliferation (IC50 = 31-125 nM) primarily in a cytostatic manner in cell lines that overexpress EGF-R or c-erbB-2, and profoundly blocked the growth of a tumor that overexpresses EGF-R in nude mice (when given orally at 80 mg/kg/day for 10 days, daily). We conclude that CL-387,785 is useful for studying the interaction of small molecules with EGF-R and may have clinical utility.

Gene assignment by polymerase chain reaction: localization of the human potassium channel IsK gene to the Down's syndrome region of chromosome 21q22.1-q22.2.

Gene mapping, using the polymerase chain reaction (PCR) on DNA obtained from a human/rodent hybrid cell line carrying only the human chromosome 21, permitted the assignment of the human IsK gene, encoding a slowly activating potassium channel, to chromosome 21. PCR analysis of two complete panels of human/rodent hybrid DNA mapped IsK to chromosome 21 with 100% concordance. By performing PCR on DNA of a human chromosome 21 regional mapping panel the gene was sublocalized to chromosome 21q22.1-q22.2, which also contains the putative Down's syndrome (trisomy 21) region. The PCR product obtained from the hybrid cell line DNA carrying only human chromosome 21 was sequenced, thus confirming that the PCR product was derived from human IsK.

Targeted gene walking by low stringency polymerase chain reaction: assignment of a putative human brain sodium channel gene (SCN3A) to chromosome 2q24-31.

We have developed a low stringency polymerase chain reaction (LSPCR) to isolate the unknown neighboring region around a known DNA sequence, thus allowing efficient targeted gene walking. The method involves the polymerase chain reaction (PCR) with a single primer under conditions of low stringency for primer annealing (40 degrees C) for the first few cycles followed by more cycles at high stringency (55 degrees C). This enables the amplification of a targeted DNA fragment along with other nontargeted fragments. High stringency (55 degrees C) nested PCRs with end-labeled primers are then used to generate a ladder of radioactive bands, which accurately identifies the targeted fragment(s). We performed LSPCR on human placental DNA using a highly conserved sodium channel-specific primer for 5 cycles at 40 degrees C followed by 27 cycles at 55 degrees C for primer annealing. Subsequently, using higher stringency (55 degrees C) PCR with radiolabeled nested primers for 8 cycles, we have isolated a 0.66-kb fragment of a putative human sodium channel gene. Partial sequence (325 bp) of this fragment revealed a 270-bp region (exon) with homology to the rat brain sodium channel III alpha (RBIII) gene at the nucleotide (87%) and amino acid (92%) levels. Therefore, we putatively assign this sequence as a part of a gene coding the alpha-subunit of a human brain type III sodium channel (SCN3A). Using PCR on two human/rodent somatic cell hybrid panels with primers specific to this putative SCN3A gene, we have localized this gene to chromosome 2. Fluorescence in situ hybridization to human metaphase chromosomes was used to sublocalize the SCN3A gene to chromosome at 2q24-31. In conclusion, LSPCR is an efficient and sensitive method for targeted gene walking and is also useful for the isolation of homologous genes in related species.

Expression of divIB of Bacillus subtilis during vegetative growth.

Expression of the division initiation gene, divIB, of Bacillus subtilis vegetative growth was examined. lacZ fusion studies and transcription start point mapping have established that a sigma A promoter proximal to divIB is utilized in vivo. The -10 region of this promoter, which is located 93 bp upstream of the start codon, has been defined precisely by site-directed mutagenesis that destroys the promoter. Examination of transcripts by Northern (RNA) blotting has shown that there are at least two transcripts for divIB. The established proximal promoter was found to give rise to a very minor transcript which could not be convincingly demonstrated in wild-type cells but which became apparent upon insertion of a plasmid into the chromosome just upstream of this promoter. The major transcript for divIB originated from a site several kb upstream of the gene and is probably the same as the long polycistronic message also traversing the murD-spoVE-murG genes that was identified previously by others (A.D. Henriques, H. de Lencastre, and P.J. Piggot, Biochimie 74:735-748, 1992). Transcription from the proximal promoter alone, in an upstream-deletion mutant strain, provided sufficient DivIB for normal growth and division as well as sporulation.

Localization of a putative human brain sodium channel gene (SCN1A) to chromosome band 2q24.

We have identified four putative human sodium channel gene sequences, 55 bp each, using the polymerase chain reaction (PCR) on total human placental DNA with primers specific for the cDNA sequence of the rat brain sodium channel I alpha (Scn1a) gene. One of these sequences was extended bidirectionally by genomic inverse-PCR to obtain a 1.6-kb fragment. Sequencing of this 1,556-bp fragment showed a 282-bp complete exon, which has 95% and 94% homology at the nucleotide and amino acid levels, respectively, with the rat Scn1a gene. We putatively assign this sequence as belonging to the gene coding the alpha-subunit of a human brain type I sodium channel (SCN1A). PCR on human x rodent somatic cell hybrids with primers derived from SCN1A localized this gene to chromosome 2. Fluorescence in situ hybridization to human metaphase chromosomes sublocalized the gene to chromosome band 2q24.

Autoregulation of the gene encoding the replication terminator protein of Bacillus subtilis.

One of two putative sigma A promoters identified previously in the region immediately upstream from the rtp gene (encoding the replication terminator protein) [Smith and Wake, J. Bacteriol. 170 (1988) 4083-4090] has been shown by transcription start point (tsp) mapping to be the functional rtp promoter. In these tsp mapping experiments, it was observed that the level of mRNA from this promoter, Prtp, was increased by a factor of 30 in the absence of the replication terminator protein (RTP), consistent with the autoregulation of rtp at the level of transcription. In vitro transcription from Prtp by sigma A RNA polymerase has been shown to be specifically repressed by RTP. A Prtp-spoVG-lacZ fusion was inserted into the chromosome of a strain in which RTP production was inducible by IPTG. Addition of IPTG to cultures of the new strain lowered beta Gal production by a factor of at least four. It is concluded that rtp is autoregulated in vivo at the level of transcription.

Promoter elements and regulation of expression of the cysD gene of Escherichia coli K-12.

The cysD gene, involved in cysteine biosynthesis in Escherichia coli and Salmonella typhimurium, is positively regulated by the CysB regulatory protein. The cysD promoter of E. coli K-12 in a 492-bp PstI-Eco RI fragment was sequenced. The in vivo transcription start point (tsp) for the cysD gene was determined by the methods of T4 DNA polymerase mapping and mung-bean nuclease mapping. The -10 region of the cysD promoter (TATAGT) is closely homologous to the -10 consensus sequence (TATAAT) for E. coli promoters. The -35 region of this promoter (TTCATT) is less closely related to the -35 consensus sequence (TTGACA). Several mutants were obtained by using a chain-termination method for generating unidirectional deletions. Evidence is presented for a possible CysB protein binding site around -89, thought to be involved in regulation of expression of the cysD gene.

Promoter-detection vectors for Escherichia coli with multiple useful features.

Two promoter-detection vectors have been constructed which enable the cloning and characterization of promoters recognized by the RNA polymerase of Escherichia coli K-12. The intergenic region of phage M13 DNA, present in opposite orientations in the two vectors, permits the preparation of single-stranded DNA of either strand of the insert thus facilitating oligodeoxyribonucleotide heteroduplex mutagenesis and sequencing of both strands by the dideoxy method of chain termination. After mutagenesis, isolates can be screened for changed function by replica-plating colonies to plates containing XGal. Selected isolates can be characterized by nucleotide sequence analysis, to determine the change in structure, and by beta-galactosidase assays, thus measuring the effect of mutagenesis on promoter function. The vectors could also be used like other protein-fusion vectors.

Lambda transducing phage and clones carrying genes of the cysJIHDC gene cluster of Escherichia coli K12.

DNA from each of two specialized transducing lambda phage, lambda dcysJIHD and lambda cysJ, has been analysed by heteroduplex mapping. The segment of the Escherichia coli chromosome carried by lambda dcysJIHD was shown to be large, approximately 18 kb in length, and to replace a large length of lambda DNA, approximately 11 kb, which includes the genes for integration and recombination. Thus lambda dcysJIHD is a bio-type transducing phage. lambda cysJ was shown to have lost very little lambda DNA and to carry about 8 kb of bacterial DNA. Sites for several restriction endonucleases were mapped in the DNA from each phage and cloning experiments located some of the genes of the cluster in relation to the restriction map. Cysteine regulation of the cloned cysJ and cysD genes was shown as well as cysteine regulation of beta-galactosidase in some constructs. The direction of transcription of the cysD gene was established, and from physical evidence the size of the 'silent section' between the cysH and cysD genes was estimated to be at least 11 kb.