Metal-Directed Synthesis of Dithia Diaza Macrocycles Carrying Pendant Alcohol and Also Nitro or Carboxylate Groups

Copper(II)-directed condensation of 1,9-diamino-3,7-dithianonan-5-ol with nitroethane or di-ethyl malonate yields (6-methyl-6-nitro-1,11-dithia-4,8-diazacyclotetradecan-13-ol)copper(II) and (diethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6,6-dicarboxylate)copper(II) respectively in good yields, with the latter readily converted by decarboxylation into the complex of ethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6-carboxylate. Analogues without the alcohol group based on 3,7-dithianonane-1,9-diamine are also described. The pendant alcohol group fused directly to a macrocyclic ring carbon can act as an axial donor group, as illustrated in the X-ray crystal structure analysis of (diethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6,6-dicarboxylate)copper(II) perchlorate . This complex crystallizes in the P21/c space group, a 12.650(3), b 8.620(1), c 24.382(4) Ǻ, β 96.10(2)°. The copper ion lies in a distorted square-based pyramidal environment of two sulfur donors (average Cu-S 2.338 A), two nitrogen donors (average Cu-N 2.035 Ǻ) and the pendant alcohol donor [Cu-O 2.319(6) Ǻ], with the copper ion displaced slightly (0.043 Ǻ) out of the macrocycle donor plane towards the pendant alcohol donor.

The germline: familiar and newly uncovered properties

Transplantations of both Drosophila pole cells and mouse primordial germ cells suggest that the pregonadal germline of these two organisms is not pluripotent. In mouse PGCs, however, the potential for activating pluripotency is clearly present, as seen in the relative case of deriving EG cells from migratory-stage PGCs. EG cells are derived from altering the in vitro growth conditions of PGCs by the addition of one factor. Conceivably, straying of PGCs in vivo could also lead to novel fates if they migrated into a suitable environment. Aberrant PGC migration underlies models for the origin of several tumor types. How are migratory-stage PGCs prevented from adopting alternative fates in wild-type development? One solution is to link accurate migration into the gonads with germ cell survival. One mechanism of accomplishing this is through the action of pleiotrophic factors such as Steel. Steel is both a proliferation and migration factor; sterility in Steel mutants is due to poor germ cell survival and improper migration. Networking of migratory PGCs is another mechanism to reduce the chances of individual germ cells straying from the migration path. Postmigratory germ cells apparently undergo another restriction on potency--novel imprinting. Assuming that EG methylation profiles accurately reflect modifications made in their founder PGCs, then "erased" pluripotent EG lines suggest that PGCs can be diverted from the germline lineage. Direct assays on PGCs show that the unmethylated phenotype at Igf2r region 2 is characteristic of late germ cells. The maintenance of germline-like methylation with a switch in PGC fate is somewhat analogous to the situation in lag mutants from Volvox, which retain large gonidial-sized cells that can nevertheless initiate somatic differentiation. Just as it is not possible to readjust cell size with a subsequent change in gonidial differentiation, it may be difficult, without gametogenesis, to reimpose methylation modifications once they have been erased. In addition, the methylation status of some sites/loci may be inconsequential to developmental gene activity in germ cells or EG cells. Recent studies indicate that the methylation imprint at Igf2r is not interpreted at functional level until embryogenesis (51). In summary, we have reviewed some distinctive properties of the development of germ cells, from their early segregation, mitotic and meiotic profile, sex determination, to their migration and sequestration into gonads. Some constraints on development of the germline likely serve to maintain its integrity until maturation, when the gametic genomes must be capable of initiating embryonic development. To accomplish this ultimate goal, germ cells in some organisms may retain a bias towards pluripotency throughout development.(ABSTRACT TRUNCATED AT 400 WORDS)

Two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate

We report that two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate in Chinese hamster ovary cells. The first enzyme initiates heparan sulfate biosynthesis and can be measured by the transfer of GlcNAc from UDP-GlcNAc to GlcUA beta 1-3Gal beta 1-O-naphthalenemethanol. The second enzyme catalyzes the polymerization of heparan sulfate and can be measured by the transfer of GlcNAc from UDP-GlcNAc to the nonreducing terminal GlcUA present in oligosaccharide fragments prepared from the Escherichia coli K5 capsular polysaccharide, N-acetylheparosan. Kinetic characterization of the initiating GlcNAc-transferase (alpha-GlcNAc-TI) indicates an apparent Km for UDP-GlcNAc of 36 +/- 4 microM. The apparent Km for UDP-GlcNAc of the polymerizing GlcNAc-transferase (alpha-GlcNAc-TII) is 230 +/- 30 microM. Both enzymes have broad pH optima and require a divalent cation for activity. alpha-GlcNAc-TI can use both Mn2+ and Ca2+, while alpha-GlcNAc-TII will use only Mn2+. Chinese hamster ovary cells deficient in the synthesis of heparan sulfate and lacking alpha-GlcNAc-TII activity and S49 Thy 1-a lymphoma cells deficient in alpha GlcNAc addition to phosphatidylinositol have wild-type alpha-GlcNAc-TI activity. Thus, distinct alpha-GlcNAc-transferases catalyze the initiation and polymerization of heparan sulfate.

A comparison of population and standard two-stage pharmacokinetic analyses of vigabatrin data

Vigabatrin (VGB), an irreversible inhibitor of GABA, is being developed as an add-on therapy for uncontrolled complex partial seizure. A single-dose study was conducted in three groups of subjects with normal, mild-to-moderate, and moderate-to-severe renal impairment to examine the effect of renal function on the pharmacokinetics of VGB. Serial blood samples were collected up to 60 h following a single 750 mg oral dose of VGB for the quantitation of drug concentrations. The plasma VGB concentration-time data were analyzed by mixed-effects modeling to estimate population pharmacokinetic parameters and to identify any significant demographic covariates. The parameters of VGB were also calculated by standard two-stage techniques and then compared to the results obtained using the mixed-effects analysis. Population VGB plasma concentration-time profiles were best described by a two-compartment model with zero-order absorption. Creatinine clearance was observed to significantly affect the oral clearance of VGB (p < 0.05), i.e. a linear increasing relationship existed between the two variables. Other demographic factors had no influence on VGB pharmacokinetics. There were agreements in the oral clearance, apparent volume of distribution during elimination, and half-life estimates calculated by both methods. In addition, the conventional technique identified a linear relationship between oral and creatinine clearances. In summary, mixed-effects modeling of serial vigabatrin data validated results determined by the standard two-stage technique.

Radiolysis of metallothionein in deaerated and oxygen-saturated solutions

Gamma radiolysis of metallothionein (MT) in phosphate-buffered solutions at pH 8.0 leads to the formation of intra- and intermolecular disulfide bridges as well as the release of chelated metal ions. When MT solutions deaerated with N2 or saturated with N2O were irradiated, G values for RS- loss as determined by Ellman's reagent were 4.2 and 7.0, respectively, whereas those for dimerization were only 0.32 and 0.67. A short chain reaction existed in the decrease in RS- when radiolysis was performed in O2-saturated solutions. The rate constants for reactions of MTs with OH radical and H2O2 were measured to be about 10(12) and 100 M-1 s-1, respectively. A mechanism for the radiolysis of MT-1 is proposed.

Evidence for sex transformation of germline cells in ovarian tumor mutants of Drosophila

Mutations at a few genetic loci in Drosophila cause ovarian tumors with hundreds of poorly differentiated germ cells. We examined several of these mutants to test the hypothesis that such ovarian tumors contain sex-transformed cells. By testing for expression of male germline traits, we determined that partial germline sex transformation occurs in otu, snf, Sxlfs, and bam ovarian tumors. Thus these genes are likely to be required for proper establishment of germline sexual identity.

Metal-Directed Synthesis of Macrocyclic Tetraamines With Pendant Nitro or Amine Groups, Based on trans-Cyclohexane-1,2-diamine

Reaction of R,R:S,S-, R,R:R,R(or S,S:S,S)- bis (trans-cyclohexane-1,2-diamine)copper(II) with formaldehyde and nitroethane in aqueous base yields the macrocyclic molecular cation (4,15-dimethyl-4,15-dimethyl-4,15-dinitro-2,6,13,17-tetraazatricyclo[16.4.0.07,12] docosane )copper(II) with two -NH-CH2-C(Me)(NO2)-CH2-NH-links completing the macrocycle, as well as the molecular cation [N,N′- bis (2-aminocyclohexyl)-2-methyl-2-nitropropane-1,3-diamine]copper(II) with a single such link inserted. The rigid polycylic macrocycle , based on a 14-membered tetraazacycloalkane ( cyclam ) frame, may exist as a number of isomers. Spectroscopic and chiroptical properties of the isolated complexes are reported. Reduction of the nitro groups with zinc in aqueous acid produces the corresponding molecules with primary amine (or ammonium) pendants in good yield, as metal-free hydrochloride salts.

Titanium nails used in A-V fistulation for hemodialysis in 428 patients

The 4-year experience in the clinical usage of titanium nails in making internal fistula for hemodialysis in 428 cases (17,829 dialyses) is reported. The results were satisfactory and no obvious complications were found. Being simple in practice and having a high success rate and less complications, this method has been applied at 86 hospitals in China.

Establishment of stable, cell-mediated immunity that makes "susceptible" mice resistant to Leishmania major

Cell-mediated, but not antibody-mediated, immune responses protect humans against certain pathogens that produce chronic diseases such as leishmaniasis. Effective vaccination against such pathogens must therefore produce an immunological "imprint" so that stable, cell-mediated immunity is induced in all individuals after natural infection. BALB/c mice "innately susceptible" to Leishmania major produce antibodies after substantial infection. In the present study, "susceptible" mice injected with a small number of parasites mounted a cell-mediated response and acquired resistance to a larger, normally pathogenic, challenge. This vaccination strategy may be applicable in diseases in which protection is dependent on cell-mediated immunity.

Electronystagmographic features in some peripheral and central vestibular disorders: application of multiple discriminant analysis of electronystagmographic parameters

In routine clinical electronystagmographic (ENG) tests (postrotatory, optokinetic, caloric and tracking tests), eye movement signals were analyzed and a multiple discriminant analysis was carried out with the aid of a microcomputer. Six parameters were selected and, based on these, two functions for discriminating between peripheral and central disorders were established. Discrimination between 35 patients with peripheral lesions and 15 patients with central lesions was made with a correct classification rate of 97.1 and 86.7%, respectively. These rates are significantly higher than that of any single ENG test analysis. Our results indicate that the clinical application of ENG can be improved by searching for more sensitive ENG parameters and adopting the comprehensive analysis approach.

Gonadal dysgenesis reveals sexual dimorphism in the embryonic germline of Drosophila

In hybrid dysgenesis, sterility can occur in both males and females. At 27.5 degrees, however, we found that P element-induced germline death was restricted to females. This sex-specific gonadal dysgenesis (GD) is complete by the first larval instar stage. As such, GD at 27.5 degrees reveals the sexually dimorphic character of the embryonic germline. The only other known dimorphic trait of the embryonic germline is the requirement for ovo. ovo is required for germline development in females only and has been implicated in germline sex determination. Dominant mutations of ovo partially suppressed female GD. Although embryonic germ cells are undifferentiated and morphologically indistinguishable between males and females, the functional dimorphism seen in ovo requirement and GD at 27.5 degrees indicates that sexual identity in Drosophila germ cells is established in embryogenesis.

A bioabsorbable delivery system for antibiotic treatment of osteomyelitis. The use of lactic acid oligomer as a carrier

We prepared a composite of D,L-lactic acid oligomer and dideoxykanamycin B for use as a biodegradable antibiotic delivery system with sustained effect. The composite was implanted in the distal portion of the rabbit femur, and the effective concentration of the antibiotic was measured in the cortex, the cancellous bone, and the bone marrow. In all bone tissues around the implant, the concentration of antibiotic exceeded the minimum inhibitory concentration for the common causative organisms of osteomyelitis for six weeks. Most of the implant material had been absorbed and the bone marrow had been repaired to a nearly normal state within nine weeks of implantation. The implant caused no systemic side effects, and it is likely to prove clinically useful as a drug delivery system for treating chronic osteomyelitis.

[Effect of vesicular-arbuscular mycorrhizal fungi on growth, nutrient uptake and synthesis of volatile oil in Schizonepeta tenuifolia briq]

Inoculating Schizonepeta tenuifolia with VA mycorrhizal fungi can significantly improve the plant growth and uptake of P and S, and influence the absorption of K, Na, Fe, Mo, Mn, Zn, Co, Ba, Ni and Pb. It is interesting to note that VA mycorrhiza can also increase the synthesis of volatile oil in the shoots of S. tenuifolia. The efficiency of VA mycorrhiza varies with the fungal species.

Multisensory integration in the human vestibular velocity storage mechanism?

To test the hypothesis that auditory inputs can interact with the optokinetically or vestibularly-charged human VSM, we examined the effects of sound on rotational nystagmus and HOKAN. Subjects were rotated at 60 degrees/s, in either clockwise (CW) or counterclockwise (CCV) direction, for a total of 3 min. After 1 min of constant rotation, the optokinetic surround (7 ft dia., 2 degrees stripes at 18 degrees intervals) was illuminated for 60 s and the ensuing HOKAN was recorded for 60 s (standard DCEOG). The chair was stopped 60 s later and the post-rotatory nystagmus (PRN) was recorded. The acoustic stimulus (4/s, 10 ms pulses) was presented to the subject by a loudspeaker in 4 randomized test conditions: (1) fixed to the surround-on during OKN, off during OKAN (2) fixed to the surround-off during OKN, on during OKAN (3) rotating with the subject-on during OKN, off during OKAN (4) rotating with the subject-off during OKN, on during OKAN. In all conditions, the sound was on during per- and post-rotatory nystagmus. Each test was performed on a different day and consisted of 4 randomized control and test trials (CW and CCW). Under none of the above conditions was the rotatory or optokinetic decay affected by the presence of stationary or rotating sound. This absence of alteration of PRN by sound cues contradicts that reported by Kollar et al. (1988). Our evidence that neither HOKAN nor post rotatory nystagmus decay is affected by sound cues supports the conclusion that, under our conditions, multisensory interaction does not occur in the human VSM.

Voltammetric determination of platinum in inorganic complexes and in water, geological and biological matrices using laboratory- and field-based instrumentation

The extremely sensitive catalytic hydrogen ion reduction wave observed after the formation of a platinum-formazone complex at a mercury electrode in a hydrazine-formaldehyde-H2SO4 medium has been utilised to determine platinum voltammetrically in well characterised platinum inorganic complexes (oxidation states O, II and IV) and in biological, geological and water samples. Experimental conditions have been optimised and sample-treatment procedures for various matrices have been critically evaluated for the quantification of platinum by the standard additions method. The determination of platinum in geological samples by this method has been compared with an inductively coupled plasma mass spectrometric method. Both conventional and portable field-based instrumentation have been used in the studies, and the possibility of developing a field-based method for the determination of platinum has been investigated. Despite the inherent sensitivity of the method, which enables concentrations down to 0.01 p.p.b. to be detected in simple matrices, natural levels in water and biological materials, where matrix effects suppress the voltammetric response, are often below the detection limit.

Application of reverse micelles for the extraction of proteins

The solubilization of proteins in hydrocarbon solutions of reverse micelles is examined at the aim of establishing whether this process can be utilized for the separation and extraction of proteins. Two techniques of solubilization are considered, the phase transfer of proteins from an aqueous solution into a supernatant micellar solution and the direct extraction of the protein powder into the micellar solution. Basic questions concerning the influence of structural parameters of the proteins, as well as the influence of external parameters (pH, salt concentration) on the specificity of the solubilization process are discussed.

Characterization of mutations that lie in the promoter-regulatory region for glnA, the structural gene encoding glutamine synthetase

In enteric bacteria products of nitrogen regulatory genes ntrA, ntrB and ntrC are known to regulate transcription both positively and negatively at glnA, the structural gene encoding glutamine synthetase [L-glutamate:ammonia-ligase (ADP-forming), EC 6.3.1.2]. We have characterized two types of cis-acting mutations in the glnA promoter-regulatory region. One type, which we have called promoter Up [glnAp (Up)], elevates transcription of glnA to high levels without need for ntr-mediated activation but leaves expression sensitive to ntr-mediated repression. The other type renders glnA transcription insensitive to repression but leaves it normally responsive to activation. Properties of the two types of promoter-regulatory mutations suggest that sites for ntr-mediated activation of glnA transcription are functionally distinct from sites for ntr-mediated repression.