The TP53 Arg72Pro and MDM2 309G>T polymorphisms are not associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers.

BACKGROUND: The TP53 pathway, in which TP53 and its negative regulator MDM2 are the central elements, has an important role in carcinogenesis, particularly in BRCA1- and BRCA2-mediated carcinogenesis. A single nucleotide polymorphism (SNP) in the promoter region of MDM2 (309T>G, rs2279744) and a coding SNP of TP53 (Arg72Pro, rs1042522) have been shown to be of functional significance. METHODS: To investigate whether these SNPs modify breast cancer risk for BRCA1 and BRCA2 mutation carriers, we pooled genotype data on the TP53 Arg72Pro SNP in 7011 mutation carriers and on the MDM2 309T>G SNP in 2222 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Data were analysed using a Cox proportional hazards model within a retrospective likelihood framework. RESULTS: No association was found between these SNPs and breast cancer risk for BRCA1 (TP53: per-allele hazard ratio (HR)=1.01, 95% confidence interval (CI): 0.93-1.10, P(trend)=0.77; MDM2: HR=0.96, 95%CI: 0.84-1.09, P(trend)=0.54) or for BRCA2 mutation carriers (TP53: HR=0.99, 95%CI: 0.87-1.12, P(trend)=0.83; MDM2: HR=0.98, 95%CI: 0.80-1.21, P(trend)=0.88). We also evaluated the potential combined effects of both SNPs on breast cancer risk, however, none of their combined genotypes showed any evidence of association. CONCLUSION: There was no evidence that TP53 Arg72Pro or MDM2 309T>G, either singly or in combination, influence breast cancer risk in BRCA1 or BRCA2 mutation carriers.

K252a, KT5720, KT5926, and U98017 support paclitaxel (taxol)-dependent cells and synergize with paclitaxel.

We have used paclitaxel-dependent Tax 2-4 cells to screen for compounds that have paclitaxel-like functional activity. The indolocarbazole serine/threonine kinase inhibitor K252a and analogues such as KT5926, KT5720, and K252b partially support the growth of the paclitaxel-dependent cells in the absence of paclitaxel. A novel kinase inhibitor of similar structure, U98017, supports the growth of the dependent cells to 48% of that seen with paclitaxel. Used in combination with paclitaxel, these compounds reduce the amount of paclitaxel required for maximum growth of the dependent cells. Isobologram analysis demonstrates that these compounds also act synergistically with paclitaxel to promote toxicity in wild-type Chinese hamster ovary cells. These selected indolocarbazoles may act at sites distinct from that of paclitaxel and may specifically inhibit kinases that contribute to the destabilization of microtubules. Other indolocarbazoles such as staurosporine and rebeccamycin do not support paclitaxel-dependent cell growth. Structurally unrelated serine/threonine kinase inhibitors such as H-9 and H-7 or tyrosine kinase inhibitors such as lavendustin do not support the growth of these cells. These results define a screen for functional paclitaxel analogues and suggest that it may be useful to investigate the possible synergy of selected indolocarbazoles and paclitaxel in vivo.

Synthesis of a series of stromelysin-selective thiadiazole urea matrix metalloproteinase inhibitors.

The synthesis and enzyme inhibition data for a series of thiadiazole urea matrix metalloproteinase (MMP) inhibitors are described. A broad screening effort was utilized to identify several thiadiazoles which were weak inhibitors of stromelysin. Optimization of the thiadiazole leads to include an alpha-amino acid side chain with variable terminal amide substituents provided a series of ureas which were moderately effective stromelysin inhibitors, with Ki's between 0.3 and 1.0 microM. The most effective analogues utilized an L-phenylalanine as the amino acid component. In particular, unsubstituted 46 had a Ki of 710 nM, while the p-fluoro analogue 52 displayed increased potency (100 nM). Stromelysin inhibition was further improved using a pentafluorophenylalanine substituent which resulted in 70, a 14 nM inhibitor. While gelatinase inhibition was generally poor, the use of 1-(2-pyridyl)piperazine as the amide component usually provided for enhanced activity, with 71 inhibiting gelatinase with a Ki of 770 nM. The combination of this heterocycle with a p-fluorophenylalanine substituent provided the only analogue, 69, with collagenase activity (13 microM). The SAR for analogues described within this series can be rationalized through consideration of the X-ray structure recently attained for70 complexed to stromelysin. Uniquely, this structure showed the inhibitor to be completely orientated on the left side of the enzyme cleft. These results suggest that thiadiazole urea heterocycles which incorporate a substituted phenylalanine can provide selective inhibitors of stromelysin. Careful selection of the amide substituent can also provide for analogues with modest gelatinase inhibition.

Interleukin-1 binding, internalization, and processing in a murine osteoblastic cell line, MC3T3.E1.

We have investigated the interaction of IL-1 and its receptor on a murine osteoblastic cell line, MC3T3.E1, with regard to binding, internalization, and the fate of the receptor-ligand complex following internalization. Binding experiments indicated that this cell line possesses a high affinity receptor (Kd 1.02 x 10(-10) M) that binds both IL-1 alpha and IL-1 beta, and has approximately 6500 receptors per cell. Cross-linking experiments indicated that the receptor has a molecular weight of 100,000 daltons. Binding of IL-1 to the receptor is inhibited by the Interleukin Receptor Antagonist Protein (IRAP). These characteristics suggest that the murine osteoblastic receptor resembles that found on T lymphocytes and fibroblasts. Internalization experiments showed that this process is fairly rapid and results in degradation of the ligand and subsequent loss of degraded IL-1 from the cell. In this respect, processing of the receptor-ligand complex mimics that observed with IL-1 receptors on murine bone marrow cells, pre-B cells, and macrophages. Although the reasons for these differences are unclear, it may be that, unlike fibroblasts, osteoblasts may function as an effector cell which rapidly removes IL-1 from the immediate environment via ligand degradation while at the same time initiating bone resorption via stimulation of osteopontin biosynthesis.

3-Trehalosamine, a new disaccharide antibiotic.

3-Amino-3-deoxy-alpha-D-glucopyranosyl-alpha-D-glucopyranoside (alpha, alpha--3-trehalosamine) was isolated from a culture of Nocardiopsis trehalosei sp. nov. (NRRL 12026). The structure was determined using a combination of spectroscopic techniques on derivatives of the component sugars, especially gas chromatography-mass spectrometry. The compound exhibited antibiotic activity against Gram-positive organisms at levels similar to what was found for the 2- and 4-trehalosamines.

Arginomycin: production, isolation, characterization and structure.

Arginomycin is a new nucleoside antibiotic produced by Streptomyces arginesis. Arginomycin, C18H28N8O5, which inhibits the growth of Gram-positive bacteria and fungi in vitro, is structurally related to blasticidin S and found to be relatively non-toxic.

A prospective comparison of ankle/brachial indices and color duplex imaging in surveillance of the in situ saphenous vein bypass.

We performed routine postoperative surveillance of 124 consecutive in situ saphenous vein bypasses, using both ankle-brachial indices and color flow duplex imaging. Using a combination of low and high velocity criteria, color flow duplex identified 97% (37/38) of bypass and native artery inflow stenoses subsequently demonstrated by angiography, including 20 of 21 severe stenoses. A reduction in ankle-brachial index by greater than 0.15 identified 43% (16/38) of all stenoses, and only 10 of 21 severe stenoses. Revisional operations were performed in 30 bypasses for abnormalities detected by surveillance, resulting in a 3-year cumulative secondary patency of 87%. Color flow duplex is a superior technique for in situ bypass surveillance when compared to alterations in ankle-brachial indices. The identification of a bypass or inflow stenosis by routine surveillance and its subsequent operative treatment result in satisfactory long-term patency.

Metabolism of dibenzothiophene by a Beijerinckia species.

Beijerinckia B8/36 when grown with succinate in the presence of dibenzothiophene, accumulated (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene and dibenzothiophene-5-oxide in the culture medium. Each metabolite was isolated in crystalline form and characterized by a variety of chemical techniques, cis-Naphthalene dihydrodiol dehydrogenase, isolated from Pseudomonas putida, oxidized (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene to a compound that was tentatively identified as 1,2-dihydroxydibenzothiophene. The same product was formed when crude cell extracts of the parent strain of Beijerinckia oxidized (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene under anaerobic conditions. Further metabolism of 1,2-dihydroxydibenzothiophene by heat-treated cell extracts led to the formation of 4[2-(3-hydroxy)-thionaphthenyl]-2-oxo-3-butenoic acid. The latter compound was metabolized by crude cell extracts to 3-hydroxy-2-formylthionaphthene. Further degradation of this metabolite was not observed.

Oxidation of naphthalene by a multicomponent enzyme system from Pseudomonas sp. strain NCIB 9816.

The initial reactions in the oxidation of naphthalene by Pseudomonas sp. strain NCIB 9816 involves the enzymatic incorporation of one molecule of oxygen into the aromatic nucleus to form (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The enzyme catalyzing this reaction, naphthalene dioxygenase, was resolved into three protein components, designated A, B, and C, by DEAE-cellulose chromatography. Incubation of naphthalene with components A, B, and C in the presence of NADH resulted in the formation of (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The ratio of oxygen and NADH utilization to product formation was 1:1:1. NADPH also served as an electron donor for naphthalene oxygenation. However, its activity was less than 50% of that observed with NADH. Component A showed NAD(P)H-cytochrome c reductase activity which was stimulated by the addition of flavin adenine dinucleotide and flavin mononucleotide. A similar stimulation was observed when these flavin nucleotides were added to the naphthalene dioxygenase assay system. These preliminary observations indicate that naphthalene dioxygenase has properties in common with both monooxygenase and dioxygenase multicomponent enzyme systems.

Interaction of cephalosporins with penicillin-binding proteins of methicillin-resistant Staphylococcus aureus.

The binding affinity of cefmetazole for penicillin binding proteins (PBPs) of methicillin resistant Staphylococcus aureus (MRSA) was compared with the affinities of cefazolin, cefotetan, and cefoxitin for these same sites. Overall, cefmetazole was found to have comparable or higher affinity for PBP1, PBP2, and PBP3 than cefoxitin or cefotetan; its affinity for these PBPs is lower than that of cefazolin. Interestingly, the antibiotic showed a somewhat greater affinity for PBP2' (PBP2a) than cefazolin, cefotetan, and cefoxitin. These results suggest that the somewhat lower MICs detected with cefmetazole for MRSA may be a consequence of the interaction of the antibiotic with PBP2'.

A simple technique of renal transplant preservation during aortic reconstruction.

Various methods of insuring renal transplant perfusion during aortic reconstruction have been described but these are often complex and troublesome. Although short periods of warm ischemia are probably well tolerated, reinstitution of pulsatile flow is more desirable. A simple method of rapidly restoring renal perfusion during aortic reconstruction is described.

In vitro antibacterial activity and interactions with beta-lactamases and penicillin-binding proteins of the new monocarbam antibiotic U-78608.

U-78608, a new monocarbam antibiotic, was evaluated for in vitro activity against 312 clinical isolates of aerobic and anaerobic bacteria and subjected to several in vitro biochemical tests characterizing its interactions with beta-lactamases and penicillin-binding proteins (PBPs). The antibacterial activity of the compound was compared directly with those of SQ 83,360 (pirazmonam) and aztreonam. U-78608, SQ 83,360, and aztreonam had generally poor activity against gram-positive aerobic bacteria and anaerobic bacteria. U-78608 demonstrated activity primarily against gram-negative aerobic bacteria, with potency generally comparable to that of SQ 83,360. U-78608 and SQ 83,360 were less active than aztreonam for some gram-negative species; however, both compounds were 8- to 64-fold more active than aztreonam against Acinetobacter species, Pseudomonas aeruginosa, and Pseudomonas maltophilia. All three compounds resisted inactivation by several different beta-lactamases from gram-positive and gram-negative bacteria. Neither U-78608 nor SQ 83,360 exhibited significant inhibition of these enzymes, while aztreonam inhibited beta-lactamases from P. aeurginosa and Klebsiella oxytoca. All three compounds exhibited strong affinity to PBP 3 of Escherichia coli and moderate to negligible affinity to the other E. coli PBPs; quantitative measurements indicated that U-78608 had greater PBP 3 affinity than either SQ 83,360 or aztreonam.

Regional autoregulatory responses during infusion of vasoconstrictor agents in conscious dogs.

We investigated pressure-dependent autoregulatory responses in mesenteric, iliac, and renal vascular beds of conscious dogs during intravenous infusion of angiotensin II, phenylephrine, or arginine vasopressin at rates which increased arterial pressure by 20-40 mmHg. The arteries supplying these beds were instrumented with an electromagnetic flow probe, a nonoccluding catheter, and an electromagnetic flow probe, a nonoccluding catheter, and an occluder cuff connected with a servo-amplifier, which enabled us to return perfusion pressure to control levels during infusion of the vasoconstrictor agents. We attempted to differentiate between the increase in vascular resistance due to the direct effect of the vasoconstrictor agent and the increase induced by an autoregulatory response induced by elevations of aortic perfusion pressure. We measured a strong degree of autoregulation in the renal vascular bed with a fractional compensation value close to 1. Moderate autoregulation occurred in the mesenteric vascular bed, where the compensation was 0.4-0.5 with angiotensin II and phenylephrine and between 0.74 and 0.94 with vasopressin. No autoregulatory capacity could be demonstrated in the hindlimb. The findings indicate that, under conditions of increased systemic blood pressure, both the renal and the mesenteric vascular beds contribute to the increase in total peripheral resistance by pressure-dependent vasoconstrictor responses.

An evaluation of color duplex scanning in the primary diagnosis and management of carotid body tumors.

Carotid body tumors present a diagnostic challenge. Despite technologic diagnostic advances, misdiagnosis resulting in blind biopsy or exploration through a limited incision still occur. Color duplex scanning has recently been used to evaluate carotid body tumors in our institution. A characteristic feature of these tumors found with this modality is wide splaying of the carotid bifurcation by a hypervascular mass. Color duplex scanning is the noninvasive modality of choice for the primary diagnosis of carotid body tumors. Additionally, it may be of use in screening for familial carotid body tumors and sequential follow-up of nonoperatively managed tumors.