Inorganic and organic sulfur cycling in salt-marsh pore waters.

Sulfur species in pore waters of the Great Marsh, Delaware, were analyzed seasonally by polarographic methods. The species determined (and their concentrations in micromoles per liter) included inorganic sulfides (

Differential effects of high fat diet and diet-induced obesity on skeletal acquisition in female C57BL/6J vs. FVB/NJ Mice.

The effects of obesity on bone metabolism are complex, and may be mediated by consumption of a high fat diet and/or by obesity-induced metabolic dysregulation. To test the hypothesis that both high fat (HF) diet and diet-induced metabolic disease independently decrease skeletal acquisition, we compared effects of HF diet on bone mass and microarchitecture in two mouse strains: diet-induced obesity (DIO)-susceptible C57BL/6J (B6) and DIO-resistant FVB/NJ (FVB). At 3 wks of age we weaned 120 female FVB and B6 mice onto normal (N, 10% Kcal/fat) or HF diet (45% Kcal/fat) and euthanized them at 6, 12 and 20 weeks of age (N = 10/grp). Outcomes included body mass; percent fat and whole-body bone mineral density (WBBMD, g/cm2) via DXA; cortical and trabecular bone architecture at the midshaft and distal femur via µCT; and marrow adiposity via histomorphometry. In FVB HF, body mass, percent body fat, WBBMD and marrow adiposity did not differ vs. N, but trabecular bone mass was lower at 6 wks of age only (p < 0.05), cortical bone geometric properties were lower at 12 wks only, and bone strength was lower at 20 wks of age only in HF vs. N (p < 0.05). In contrast, B6 HF had higher body mass, percent body fat, and leptin vs. N. B6 HF also had higher WBBMD (p < 0.05) at 9 and 12 wks of age but lower distal femur trabecular bone mass at 12 wks of age, and lower body mass-adjusted cortical bone properties at 20 wks of age compared to N (p < 0.05). Marrow adiposity was also markedly higher in B6 HF vs. N. Overall, HF diet negatively affected bone mass in both strains, but was more deleterious to trabecular bone microarchitecture and marrow adiposity in B6 than in FVB mice. These data suggest that in addition to fat consumption itself, the metabolic response to high fat diet independently alters skeletal acquisition in obesity.

Synthesis and spectroscopic characterization of site-specific 2-amino-1-methyl-6-phenylimidazo.

The aim of the present study is to determine the chemical structure and conformation of DNA adducts formed by incubation of the bioactive form of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), N-acetoxy-PhIP, with a single-stranded 11mer oligodeoxyribonucleotide. Using conditions optimized to give the C8-dG-PhIP adduct as the major product, sufficient material was synthesized for NMR solution structure determination. The NMR data indicate that in duplex DNA this adduct exists in equilibrium between two different conformational states. In the main conformer, the covalently bound PhIP molecule intercalates in the helix, whilst in the minor conformation the PhIP ligand is probably solvent exposed. In addition to the C8-dG-PhIP adduct, at least eight polar adducts are found after reaction of N-acetoxy-PhIP with the oligonucleotide. Three of these were purified for further characterization and shown to exhibit lowest energy UV absorption bands in the range 342-347 nm, confirming the presence of PhIP or PhIP derivative. Accurate mass determination of two of the polar adducts by negative ion MALDI-TOF MS revealed ions consistent with a spirobisguanidino-PhIP derivative and a ring-opened adduct. The third adduct, which has the same mass as the C8-dG-PhIP oligonucleotide adduct, may contain PhIP bound to the N2 position of guanine.

Psychiatric Darwinism = survival of the fittest + extinction of the unfit.

This article is a critical analysis of the American Health Security Act of 1993. Although AHSA was soundly defeated when first proposed, parts of it have been enacted into law in 1996, with the prospect of further piece-meal enactments in the future. It includes matters of fundamental importance to American mental health practitioners, to vulnerable citizens with psychiatric disorders, to their families, and to their few champions in medicine and law. Utilitarianism is the unstated philosophical substructure of AHSA and its legislative progeny, i.e., whatever cuts medical costs and saves money is good. The author delineates AHSA's mental health entitlements and limitations of in-patient, out-patient, and other patient care. She enumerates a dozen major imperfections and dangers of this mental health law, especially its medical utilitarianism emphasizing outcomes and quality of life. Dr. Cosman argues that medical cost, outcome, quality of life, and managed competition threaten the essential liberties and the lives of older persons, persons who are chronically ill, fatally ill, and most particularly those who are mentally impaired. She concludes that if limited money, medicine and time are invested only in inevitable medical success, then America's medicine by its medical law will be Medical Darwinism encouraging survival of the fittest by requiring extinction of the unfit.

The medieval medical third party: compulsory consultation and malpractice insurance.

Medical third-party intervention was a venerable medieval tradition. Fifteenth century London's medical malpractice legislation and court cases contained forms of peer review, compulsory consultation for critical cases, and a malpractice insurance "floater" policy for conditions likely to lead to death, maiming, or accusations of malpractice. A four-part Latin document from 1415 and a few earlier and later manuscript rules demonstrate the role of politics in medical ethics; civil enforcement of surgical guild regulations; and ingenious forms of protection for patient, practitioner, the surgical profession, and the English citizenry. Pairing compulsory consultation with malpractice insurance policies for high-risk cases offers inspiration for alleviating some modern malpractice perils.

[Evaluation of the effectiveness of serological typing in subdifferentiation of strains of Klebsiella of extraenteral origin]. / Evaluarea eficientei tipajului serologic în cadrul subdiferentierii tulpinilor de Klebsiella de provenienta extraenterala.

The present study reports on the results of capsular serotyping of Klebsiella strains isolated between 1971 and 1972, carried out in view of the subdivision of the genus. Serologic typing was performed with K1--K80 sera on 156 Klebsiella strains, isolated from in-hospital cases of extraenteral klebsiella infections. The 140 (90%) strains typed were listed in 34 capsular serotypes. Another 16 strains (10%) could not be typed because of their insufficient capsular coating. The following 13 serotypes were predominant: K4 (13.57%), K2 (7.85%), K16 (6.42%), K18 (6.42%), K27 (5%), K20 (4.28%), K24 (4.28%), K55 (4.28%), K68 (4.28%), K48 (3.55%), K15 (2.85%), K17 (2.85%), representing 70.71%. In the feces samples from the healthy controls serotypes K7, K14, K30, K1, K2, K24, K27, K47 etc. may be considered omnipresent. It has been demonstrated that in periods of minimal epidemiological survey, these serotypes from healthy carriers may initiate nosocomial infections. The present findings emphasize the accessibility and value of serologic typing of klebsiellas according to clinical and epidemiologic indications. The serologic type is a marker that can be included on the programme of systematic typing of in-hospital strains.

[Additional anti-Klebsiella phages used in lysotyping of Klebsiella strains]. / Fagi aditionali anti-Klebsiella folositi în lizotipia tulpinilor de Klebsiella.

In order to increase the efficiency of lysotyping as a method for differentiating Klebsiella strains the authors tested the activity of 10 additional phages isolated, prepared and studied in the laboratory and compared to the Slopek-Milch set. A number of 734 Klebsiella strains were isolated in different clinical and epidemiological conditions and lysotyped. The phage type was determined in 64.60% of the strains examined, using 15 phages of the Slopek-Milch set. By using additional autochtonous phages the proportion of lysotypable strains reached 77.80%; therefore, 13.20% were sensitive only to the additional phages.

Salmonella serotype typhimurium phage typing. A critical evaluation.

Of 12,930 Salmonella serotype typhimurium strains, phage typed during 1985-1988, 45.68% were "nontypable" by Anderson's set; the percent of typable strains decreased from 54.17 in 1986 to 30.54 in 1988. Of 90 phage patterns of sensitivity, 22 were currently encountered. Phage types 1, 18 and 104 were most frequent to strain of both human and non-human origin. In food generating S. typhimurium outbreaks, phage types 1 and 36 were prevalent. Except lysotypes 198 and 95, isolated from "single cases" in man only, all other phage types were common in man and animals, too. Introducing other typing methods to serotype typhimurium "nontypable" strains (by Anderson's set) was considered necessary for epidemiological purposes.

An empirical relationship between rotational correlation time and solvent accessible surface area.

Structure-dynamics interrelationships are important in understanding protein function. We have explored the empirical relationship between rotational correlation times (tau(c) and the solvent accessible surface areas (SASA) of 75 proteins with known structures. The theoretical correlation between SASA and tau(c) through the equation SASA = K(r)tau(c) ((2/3)) is also considered. SASA was determined from the structure, tau(c) (calc) was determined from diffusion tensor calculations, and tau(c) (expt) was determined from NMR backbone(13) C or (15)N relaxation rate measurements. The theoretical and experimental values of tau(c) correlate with SASA with regression analyses values of K(r) as 1696 and 1896 m(2)s(-(2/3)), respectively, and with corresponding correlation coefficients of 0.92 and 0.70.

Restriction and modification of typing phages by an R factor in S. typhi.

We have investigated the qualities of one R factor 552 discovered on a strain of S. typhi resistant to A, C, S, T, nontypable, isolated from stool cultures; from the same patient, before starting the treatment we isolated, from his blood sample, the strain S. typhi 221, sensitive to A, C, T, degraded phage-type Vi A. Factor R 552 fi- when infecting strains of S. typhi Vi A and of A degraded 221- leads to the conversion of the respective phage-types into non-typable ones, as a result of the restricting and modifying effect on phage Vi A and on the derivatives resulting from it. Derivative R 552-1 as a resistance marker to ampicilline has a restrictive effect on the phage of S. panama A 47 too. Not taking into account possible causes such as spontaneous mutation, lysogeny, and adsorption of phages, we reach for the conclusion that R factor 552, through is restrictive effect, is the only cause responsible for the existence in the same patient of two strains of S. typhi different from the point of view of phage-type and antibiotype.

Preparation and isolation of adducts in high yield derived from the binding of two benzo[a]pyrene-7,8-dihydroxy-9,10-oxide stereoisomers to the oligonucleotide d(ATATGTATA).

The reaction of the (+)- and (-)-enantiomers of BDPE trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene) with the oligodeoxynucleotide d(ATATGTATA) in aqueous buffer solutions gives rise predominantly to trans and cis addition products at the exocyclic amino group of the single deoxyguanosine residue. The trans/cis ratios are 7:1 in the case of (+)-BPDE, and 2:1 in the case of (-)-BPDE, while the reaction yields correspond to 34 and 15% respectively, of modified strands. These relatively high reaction efficiencies, at least for this particular type of oligonucleotide sequence, offer the possibilities of synthesizing relatively large amounts of well-defined covalent BPDE-oligonucleotide adducts (with different sequences of nucleotides flanking the modified base) for detailed spectroscopic and biochemical studies.

Opposite stereoselective resistance to digestion by phosphodiesterases I and II of benzo[a]pyrene diol epoxide-modified oligonucleotide adducts.

The deoxyribooligonucleotide 5'-d(CTCACATGTACACTCT) was reacted separately with the chiral diol epoxide isomers 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha- epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE)] and 7 alpha, 8 beta-dihydroxy-9 beta, 10 beta-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene [(-)-anti-BPDE)], to produce the modified oligonucleotides 5'-d(CTCACATGBPDETACACTCT). Adducts in which either (+)-anti-BPDE or (-)-anti-BPDE are covalently bound via their C10 positions by trans addition to the exocyclic amino group of the single G residues were isolated and purified by HPLC methods. Snake venom phosphodiesterase (SVPD, phosphodiesterase I), which hydrolyzes DNA from the 3'-OH terminus to the 5'-end, digests the (+)-trans-anti-BPDE-oligonucleotide adducts at a significantly faster rate than that of the sterically different (-)-trans-anti-BPDE-oligonucleotide adducts. However, using spleen phosphodiesterase (SPD, phosphodiesterase II), which hydrolyzes DNA in the 5'-->3' direction, the opposite stereoselective resistance to digestion is observed. Using shorter BPDE-modified oligonucleotides as standards, the enzyme stall sites have been defined by gel electrophoresis methods; the most digestion-resistant phosphodiester linkage is the 5'-d(...T-G*...)-3' bond in the case of (+)-trans-BPDE-modified oligonucleotide adducts for both enzymes, SVPD and SPD (the starred G denotes the site of BPDE modification). In the case of the (-)-trans-BPDE-modified oligonucleotide adducts, the phosphodiester bond on the 3'-side of the modified G [5'-d(...G*-T...)-3'] is most resistant to digestion by both enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Solution structure and backbone dynamics of the human DNA ligase IIIalpha BRCT domain.

BRCT (BRCA1 carboxyl terminus) domains are found in a number of DNA repair enzymes and cell cycle regulators and are believed to mediate important protein-protein interactions. The DNA ligase IIIalpha BRCT domain partners with the distal BRCT domain of the DNA repair protein XRCC1 (X1BRCTb) in the DNA base excision repair (BER) pathway. To elucidate the mechanisms by which these two domains can interact, we have determined the solution structure of human ligase IIIalpha BRCT (L3[86], residues 837-922). The structure of L3[86] consists of a beta2beta1beta3beta4 parallel sheet with a two-alpha-helix bundle packed against one face of the sheet. This fold is conserved in several proteins having a wide range of activities, including X1BRCTb [Zhang, X. D., et al. (1998) EMBO J. 17, 6404-6411]. L3[86] exists as a dimer in solution, but an insufficient number of NOE restraints precluded the determination of the homodimer structure. However, 13C isotope-filtered and hydrogen-deuterium exchange experiments indicate that the N-terminus, alpha1, the alpha1-beta2 loop, and the three residues following alpha2 are involved in forming the dimer interface, as similarly observed in the structure of X1BRCTb. NOE and dynamic data indicate that several residues (837-844) in the N-terminal region appear to interconvert between helix and random coil conformations. Further studies of other BRCT domains and of their complexes are needed to address how these proteins interact with one another, and to shed light on how mutations can lead to disruption of function and ultimately disease.

Site-specific adducts derived from the binding of anti-5-methylchrysene diol epoxide enantiomers to DNA: synthesis and characteristics.

The direct synthesis and characterization of site-specific adducts derived from the binding of (+)-1R,2S-dihydroxy-3S,4R-epoxide-1,2,3,4-tetrahydro-5-methylchrysene and the (-)-1S,2R,3R,4S-enantiomer [(+)- and (-)-5-MeCDE, respectively], to the N2-guanine residues in the oligonucleotide d(CCATCGCTACC) are described. The spectroscopic characteristics of the 5-MeCDE-modified oligonucleotides are discussed, and it is shown that their CD characteristics can be used to distinguish between the trans-addition products of the binding of the (+)- and (-)-enantiomers of 5-MeCDE (C4 position). The 11-mer duplexes with the normal complementary strands are destabilized by the site-specific, covalently bound 5-MeCDE residues: the melting points, Tm, are 5-10 degrees lower than in the case of the unmodified duplex. Stereoselective exonuclease enzyme digestion patterns of the single-stranded (+)- and (-)-trans-5-MeCDE-modified oligonucleotides (Mao et al, 1993, Biochemistry, 32, 11785-11793) were used to probe the orientations of the covalently bound 5-MeCDE residues relative to the modified guanine and the 5'-3' strand polarity; the aromatic residues are positioned either on the 5'-side [(+)-5-MeCDE], or the 3'-side [(-)-5-MeCDE adduct] of the modified guanine residues. The electrophoretic mobilities of the (+)-5-MeCDE-modified 11-mer duplexes in native polyacrylamide gels are slower than those of unmodified and modified duplexes containing the stereoisomeric (-)-5-MeCDE-N2-dG lesions. This indicates that the lesions derived from the tumorigenic (+)-5-MeCDE induce greater degrees of bending or local flexibility than the non-tumorigenic (-)-5- MeCDE enantiomer. These differences in the orientational and structural characteristics are similar to those observed with analogous DNA adducts derived from the tumorigenic (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene and the non-tumorigenic 7S,8R,9R,10S-enantiomer, respectively. The adducts derived from BPDE and 5-MeCDE enantiomers thus display similar characteristics that depend primarily on the PAH diol epoxide enantiomer stereochemistry. This direct synthesis approach can be used to generate milligram quantities of site-specific 5-MeCDE-modified oligonucleotides that are suitable for NMR studies (Cosman, et al., 1995, Biochemistry, 34, 6247-6260).

Structural alignments of (+)- and (-)-trans-anti-benzo[a]pyrene-dG adducts positioned at a DNA template-primer junction.

The structural features of a chemically modified DNA template strand may promote error-prone DNA synthesis during replication. The resulting higher incidence of mutations, in turn, can eventually lead to tumor initiation. Structural insights into this process can be monitored by studying chemically modified base adducts of defined stereochemistry positioned site-specifically at a single strand--duplex template--primer junction. We have used a NMR-molecular mechanics approach to obtain the solution conformations of the covalent adducts derived from trans additions at the [BP]C10 position of the highly tumorigenic (+)-anti-benzo[a]pyrene diol epoxide [(+)-anti-BPDE] and nontumorigenic (-)-anti-benzo-[a]pyrene diol epoxide [(-)-anti-BPDE] to the N2 position of guanine [(+) and (-)-trans-anti-[BP]dG, respectively] in the d(A1-A2-C3-[BP]G4-C5-T6-A7-C8-C9-A10-T11-C12-C13).d (G14-G15-A16-T17-G18-G19-T20-A 21-G22) 13/9-mer DNA sequence. The modified 13-mer strand constitutes the template strand, while the complementary 9-mer strand constitutes a primer which has been synthesized from the 3'-end of the template toward the 5'-end up to the base preceding, but not including, the modified guanine. The modified guanine (denoted by [BP]dG4) is positioned at the junction site between the single-stranded and duplex segments. Structural features of the (+)-trans-anti-[BP]dG 13/9-mer have been determined by incorporating proton--proton distances defined by lower and upper bounds deduced from NOESY spectra as restraints in molecular mechanics computations in torsion angle space. The 3'-side duplex segment retains a minimally perturbed B-DNA conformation with all nine base pairs in Watson--Crick hydrogen-bonded alignments. Conformational heterogeneity is detected at the single-stranded d(A1-A2-C3) segment located 5' to the modified (+)-trans-anti-[BP]dG lesion which contrasts with an unperturbed alignment of these same residues in the unmodified control 13/9-mer. The modified guanine adopts a syn glycosidic torsion angle, is displaced into the major groove, and no longer stacks over the adjacent dC5.dG22 base pair. Such a base displacement is accompanied by stacking of one face of the pyrenyl ring with the dC5.dG22 base pair located on the duplex segment proximate to the modified guanine, while the other face of BP is exposed to solvent.(ABSTRACT TRUNCATED AT 400 WORDS)

Spectroscopic characteristics and site I/site II classification of cis and trans benzo[a]pyrene diolepoxide enantiomer-guanosine adducts in oligonucleotides and polynucleotides.

The highly tumorigenic isomer (+)-7,8-dihydroxy-anti-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE] and its non-tumorigenic enantiomer (-)-anti-BPDE are known to react predominantly with the exocyclic amino group (N2) of deoxyguanine in DNA and to form adducts of different conformations. The spectroscopic characteristics (UV absorbance, fluorescence and circular dichroism) of stereochemically defined (+)-trans, (-)-trans, (+)-cis and (-)-cis d(5'-CACATGBPDETACAC) adducts in the single-stranded form, or complexed with the complementary strand d(5'-GTGTACATGTG) in aqueous solution, were investigated. The spectroscopic characteristics of the double-stranded d(5'-CACATGBPDETACAC).d(5'-GTGTACATGTG) adducts can be interpreted in terms of two types of conformations. In site I-type conformations, there is an approximately 10 nm red shift in the absorption maxima, which is attributed to significant pyrenyl residue-base interactions; in site II-type adducts, the red shift is only approximately 2-3 nm, and the pyrene ring system is located at external, solvent-exposed binding sites. The spectroscopic characteristics of the BPDE-modified duplexes are of the site II type for the (+)- and (-)-trans, and of the site I type for the (+)- and (-)-cis adducts. In adducts derived from the binding of (+)-anti-BPDE to poly(dG-dC).(dG-dC) and poly(dG).(dC), the trans/cis BPDE-N2-dG adduct ratio is 6 +/- 1; in the case of (-)-anti-BPDE this ratio is only 0.4 +/- 0.1 and 0.6 +/- 0.15 in poly(dG-dC).(dG-dC) and poly(dG).(dC) respectively. The spectroscopic properties of these BPDE-modified polynucleotide adducts are consistent with those of the BPDE-modified oligonucleotide complexes; the cis adducts are correlated with site I adduct conformations, while the trans adducts are of the site II type. The correlations between adduct characteristics and biological activities of the two BPDE enantiomers are discussed.