Sequence, heterologous expression and functional characterization of tryparedoxin1 from Crithidia fasciculata

Tryparedoxin (TXN) has recently been discovered as a constituent of the complex peroxidase system in the trypanosomatid Crithidia fasciculata [Nogoceke et al. (1997) Biol. Chem. 378, 827-836] where it catalyzes the reduction of a peroxiredoxin-type peroxidase by trypanothione. Here we report on the full-length DNA sequence of the TXN previously isolated from C. fasciculata (TXN1). The deduced amino acid sequence comprises 147 residues and matches with all the peptide sequences of fragments obtained from TXN1. It shares a characteristic sequence motif YFSAxWCPPCR with some thioredoxin-related proteins of unknown function. This motif is homologous with the CXXC motif, which characterizes the thioredoxin superfamily of proteins and is known to catalyze disulfide reductions. Sequence conservations between TXNs and the typical thioredoxins are restricted to the intimate environment of the CXXC motif and three more remote residues presumed to contribute to the folding pattern of the thioredoxin-type proteins. The TXNs thus form a distinct molecular clade within the thioredoxin superfamily. TXN1 was expressed in Escherichia coli BL21 (DE3)pLysS as a C-terminally extended and His-tagged protein, isolated by chelate chromatography and characterized functionally. The recombinant product exhibited a kinetic pattern identical with, and kinetic parameters similar to those of the authentic enzyme in the trypanothione/peroxiredoxin oxidoreductase assay. The recombinant TXN1 can therefore be considered a valuable tool for the screening of specific inhibitors as potential trypanocidal agents.

In vitro encystation and excystation of Blastocystis ratti

Cysts of Blastocystis ratti were produced in vitro by culturing the parasite in Iscove's modified Dulbecco's medium (IMDM) with increasing concentrations of horse serum. Yields up to 3 x 10(6) cysts/ml of culture medium were obtained after 72 h. Encystation efficiency was time, strain and inoculum size dependent. A viability of > 70% was determined by flow cytometry employing fluorescein diacetate and propidium iodide staining. The presence of chitin as a cyst wall component was demonstrated by Calcofluor White M2R staining with which cystic stages showed blue fluorescence. The changes in morphology during excystation were examined by transmission electron microscopy. The cyst enlarged in size and some vacuoles appeared within the condensed cytoplasm. The vacuoles were full of inclusions and small glycogen aggregates. Coalescence of the vacuoles led to central body formation. Glycogen deposits were prominent throughout the excystation process. Some cysts divided by binary fission before the completion of the excystation.

Immunogenicity and protective efficacy of tuberculosis DNA vaccines encoding putative phosphate transport receptors

Using culture filtrate Ag-specific mAbs generated from mycobacteria-infected H-2b haplotype mice, we have previously identified three genes in the Mycobacterium tuberculosis genome, encoding proteins homologous to the periplasmic ATP-binding cassette phosphate-binding receptor PstS of the phosphate-specific transport system of E. coli. To define the potential vaccinal properties of these phosphate-binding proteins, female C57BL/6 mice were injected i.m. with plasmid DNA encoding PstS-1, PstS-2, or PstS-3 proteins from M. tuberculosis and immunogenicity and protective efficacy against i.v. challenge with M. tuberculosis H37Rv was analyzed. Significant levels of highly Ag-specific Abs and Th1-type cytokines IL-2 and IFN-gamma could be detected following vaccination with each of the three genes. However, only mice vaccinated with PstS-3 DNA demonstrated significant and sustained reduction in bacterial CFU numbers in spleen and lungs for 3 mo after M. tuberculosis challenge, as compared with CFU counts in mice vaccinated with control DNA. Vaccination with PstS-2 DNA induced a modest reduction in CFU counts in spleen only, whereas vaccination with PstS-1 DNA was completely ineffective in reducing bacterial multiplication. In conclusion, our results indicate that DNA vaccination is a powerful and easy method for comparative screening of potentially protective Ags from M. tuberculosis and that the PstS-3 protein is a promising new subunit vaccine candidate.

Studies with lysine N6-hydroxylase. Effect of a mutation in the assumed FAD binding site on coenzyme affinities and on lysine hydroxylating activity

The proposed FAD binding site of L-lysine N6-hydroxylase (EC 1.14.13.99) exhibits an unusual proline in a position where a highly conserved glycine is found in other FAD dependent hydroxylases. We have studied the role of this proline by mutating it to glycine in [P14G]aerA, which was expressed in Escherichia coli M15-2 and purified to homogeneity. The mutation has marked effects on the affinities of the cofactors FAD and NADPH as well as the substrate, lysine. Compared to the wild-type enzyme, the activity vs. pH profile of the mutant protein indicates a shift of the apparent pK'(a)s (7.8 and 8.7 for wild-type and 6.8 and 7.7 for the P14G-mutant enzyme) and of the activity maximum (pH 8 for wild-type and pH 7 for the P14G-mutant enzyme). While the activity of the mutant enzyme is much lower under conditions found to be optimal for the wild-type enzyme, adjustment of substrate and cofactor concentrations and pH leads to comparable activities for the mutant enzyme. These results suggest that the proline fulfils an important structural role in the proposed FAD binding site.

A recombinant measles virus expressing biologically active human interleukin-12

Suppression of cell-mediated immunity (CMI) is well-documented during and after measles. This immunosuppression is suggested to result from decreased production of interleukin-12 (IL-12), a key interleukin for CMI. In an attempt to clearly discern the role of IL-12 in measles-induced immunosuppression, a measles virus (MV) that expresses biologically active human IL-12 was generated. This was achieved by inserting the coding sequences of the two subunits (p35 and p40) of human IL-12 separated by an internal ribosome entry site in an additional transcription unit between the H and the L genes of MV. Although the IL-12-expressing MV grew slightly slower than the normal MV, it stably maintained the inserted sequences (3.2 kb) and uniformly expressed the foreign genes after 10 passages in cell culture. These findings suggest that MV is a well-suited vector for delivery of proteins of immunogenic and therapeutic importance.

A methodology for partitioning a vocabulary hierarchy into trees

Controlled medical vocabularies are useful in application areas such as medical information systems and decision-support systems. However, such vocabularies are large and complex, and working with them can be daunting. It is important to provide a means for orienting vocabulary designers and users to the vocabulary's contents. We describe a methodology for partitioning a vocabulary based on an IS-A hierarchy into small meaningful pieces. The methodology uses our disciplined modeling framework to refine the IS-A hierarchy according to prescribed rules in a process carried out by a user in conjunction with the computer. The partitioning of the hierarchy implies a partitioning of the vocabulary. We demonstrate the methodology with respect to a complex sample of the MED, an existing medical vocabulary.

Chlamydia trachomatis infection among pregnant women: prevalence and prenatal importance

BACKGROUND

Chlamydia trachomatis infection in pregnant women is suspected to result in low birth-weight and premature infants. We conducted studies to ascertain the prevalence of this infection among pregnant women in our setting and whether its presence is a risk factor for low birth-weight or prematurity.

METHODS

In the first study, 94 pregnant women between 26 and 30 weeks of gestation were screened for infection with Chlamydia trachomatis. The second investigated a cohort of 172 pregnant women presenting in spontaneous labour. The infection status was related to perinatal outcome in terms of birth-weight and gestation. In both the studies, Chlamydia trachomatis infection was diagnosed using the Chlamydiazyme test performed on endocervical swabs.

RESULTS

The prevalence of Chlamydia trachomatis infection in mid-pregnancy and at labour was 17% (16/94) and 18.6% (32/172), respectively. Women with infection were relatively older than those without it [mean (SD) age: 26.6 (4.5) years v. 24.8 (3.6) years, p = 0.01]. The mean (SD) birth-weight [2869 (611) g v. 2814 (496) g], gestation [38.5 (2.6) weeks v. 38.3 (2.0) weeks], and incidence of low birth-weight [18.7% v. 20.7%] as well as prematurity [9.4% v. 10.7%] were similar among neonates born to women with or without infection. Neonates born to infected mothers experienced purulent conjunctivitis more frequently than those born to non-infected mothers [12.5% v. 2.8%, p = 0.04].

CONCLUSION

Chlamydia trachomatis is a relatively common infection in pregnant women. However, it was not associated with either low birth-weight or prematurity.

Arene dioxides of substituted pyrenes: synthesis and X-ray structural studies

The arene dioxides of five 1-substituted pyrenes have been synthesized using dimethyldioxirane. The diasteroisomeric distribution of the dioxides has been determined. X-ray crystallographic structures of the dioxides have also been obtained. These structures show that for the cis dioxides the molecular structures show a departure from planarity, the extent of which is dependent on the substituent.

Esthesioneuroblastoma - a rarity

A young male presented with visual complaints of one year duration, epistaxis and nasal blockage of 3 months duration. He had bilateral proptosis and bitemporal hemianopia and a mass near the; roof of nasal cavity. Skull skiagram showed enlarged sella and computed tomography showed erosion of sella and a central mass. Partial excision of supra and parasellar tumour was done which on histopatho-logical examination revealed Esthesioneuroblastoma. This was followed by radiotherapy and CCNU twice, at 6 weeks interval. He is doing well after 1 year and 9 months of follow up.

Reversal of a novel multidrug resistance mechanism in human colon carcinoma cells by fumitremorgin C

We selected a human colon carcinoma cell line in increasing concentrations of mitoxantrone to obtain a resistant subline, S1-M1-3.2, with the following characteristics: profound resistance to mitoxantrone; significant cross-resistance to doxorubicin, bisantrene, and topotecan; and very low levels of resistance to Taxol, vinblastine, colchicine, and camptothecin. This multidrug resistance (MDR) phenotype, which was not reversed by verapamil or another potent P-glycoprotein (Pgp) inhibitor, CL 329,753, was dependent, in part, upon an energy-dependent drug efflux mechanism. Pgp and the multidrug resistance protein (MRP) were not elevated in the resistant cells relative to the drug-sensitive parent, suggesting that resistance was mediated by a novel pathway of drug transport. A cell-based screen with S1-M1-3.2 cells was used to identify agents capable of circumventing this non-Pgp, non-MRP MDR. One of the active agents identified was a mycotoxin, fumitremorgin C. This molecule was extremely effective in reversing resistance to mitoxantrone, doxorubicin, and topotecan in multidrug-selected cell lines showing this novel phenotype. Reversal of resistance was associated with an increase in drug accumulation. The compound did not reverse drug resistance in cells with elevated expression of Pgp or MRP. We suggest that fumitremorgin C is a highly selective chemosensitizing agent for the resistance pathway we have identified and can be used as a specific pharmacological probe to distinguish between the diverse resistance mechanisms that occur in the MDR cell.

Temporal sequence of mammary intraductal proliferations, ductal carcinomas in situ and adenocarcinomas induced by 1-methyl-1-nitrosourea in rats

An experimental model for mammary carcinogenesis has been described in which intraductal proliferations, ductal carcinomas in situ and adenocarcinomas can be readily detected and the frequency of their occurrence quantified. The objective of the experiment reported in this study was to determine the latency period between carcinogen administration and the occurrence of each of these types of lesion. A total of 150 female Sprague-Dawley rats were injected i.p. with 50 mg 1-methyl-1-nitrosourea (MNU)/kg body wt at 21 days of age. Groups of 30 rats each were killed at 7, 14, 21, 28 and 35 days post-carcinogen. Mammary intraductal proliferations were the first detected lesions and were observed in 20% of the animals at 14 days following carcinogen administration. At 21 days post-carcinogen ductal carcinomas in situ and adenocarcinomas were observed. The number of each type of lesion increased with time post-carcinogen, but the temporal pattern of occurrence was different among lesion types. The pattern of lesion occurrence was consistent with intraductal proliferations being a precursor lesion for ductal carcinomas in situ and adenocarcinomas. Furthermore, the data imply that ductal carcinomas in situ represent one pathway of morphological progression by which intraductal proliferations evolve into invasive carcinomas, but that this lesion type, as currently defined histologically, may not be an obligatory intermediate in morphologic progression. These findings are consistent with emerging evidence of multiple but distinct pathogenetic pathways leading to mammary carcinomas that display different morphological patterns and biological activities.

Is zero dose oral polio vaccine effective in preterm babies?

A randomized controlled trial was done to compare seroconversion following a single dose of trivalent oral polio vaccine (TOPV) in preterm babies, vaccinated at two different post-conception ages, with that of term newborns. Sixty-two consecutive preterm babies < or = 35 weeks were randomly allocated to two groups. Group A was vaccinated 'early' at 34-35 weeks and group B 'late' at 38-40 weeks post conception. The two groups were comparable in birthweight [mean (SD) 1594 g (118) and 1599 g (126), respectively] and gestational age [mean (SD) 33.2 (1.2) and 33 (1.3) weeks, respectively]. A control group of 36 term babies (group C) were vaccinated in the 1st week of life. Polio virus antibodies were measured immediately before and 6-8 weeks after vaccination. Group A had seroconversion rates of 54.2, 12.5 and 12.5% against polio virus types 1, 2 and 3, respectively, group B had rates of 60.0, 8.0 and 16.0%, and group C rates of 53.6, 10.7 and 14.3%. Differences in the seroconversion rates in the three groups were not statistically significant. The conversion rates against types 2 and 3 are much lower than in previous studies. We conclude that preterm babies vaccinated at 34-35 weeks post conception show seroconversion rates similar to those in term newborns.

The preparation and characterization of polymeric antigen delivery systems for oral administration

Although polymeric delivery systems are well established for the oral administration of conventional drugs, they have not yet been commercially developed for vaccine delivery. The problems inherent with the oral route of delivery, including low pH, gastric enzymes, rapid transit and poor absorption of large molecules, has made the goal of oral delivery of antigens very challenging. Nevertheless, several polymeric delivery systems for the oral administration of vaccines are currently being evaluated, including microencapsulation in poly(lactide-co-glycolides), alginates, polyanhydrides, starch, polymethacrylates, polyamino acids and enteric coating polymers. These approaches are designed to protect the antigen in the gut, to target the antigen to the gut-associated lymphoid tissue, or to increase the residence time of the antigen in the gut through bioadhesion. Each of these approaches is discussed in relation to antigen encapsulation and integrity, process reproducibility, ease of preparation and encapsulation efficiency. Potential problems associated with the scale-up of these approaches are also briefly addressed. Of particular relevance are the prospects for the application of these formulation processes for commercial development.

Histologic chorioamnionitis & its association with prematurity in a hospital-based study

This prospective study was undertaken to study the occurrence of histologic chorioamnionitis and determine its association with prematurity; and to assess whether colonization of the genital tract of pregnant women by genital mycoplasmas or Chlamydia trachomatis is a risk factor for histologic chorioamnionitis. A total of 268 women with singleton pregnancies of over 26 weeks gestation were subjected to high vaginal cultures of genital mycoplasmas and endocervical specimens for chlamydia antigen. Placental histopathology was performed on multiple sections. Histologic chorioamnionitis was documented in 22.4 per cent (60/208) placentae. Genital tract colonization with Ureaplasma urealyticum or C. trachomatis was not a risk factor for histologic chorioamnionitis. Neonates born in association with histologic chorioamnionitis had a mean birth weight 111 g lower than those born without this lesion (2626.9 +/- 702 g vs 2737.8 +/- 500 g, NS). The relative risk (95% confidence interval) of prematurity in the presence of histologic chorioamnionitis was 1.49 (0.87-2.53). Analysis of linear trend in proportions for prevalence of histologic chorioamnionitis with decreasing gestation showed a significant association (P = 0.047, 1-tail). These results taken together suggest that histologic chorioamnionitis may be a risk factor of prematurity, but of only a modest magnitude.

CD8(+), radiosensitive T cells of parental origin, oppose cells capable of down-regulating cytotoxicity in murine acute lethal graft-versus-host disease

Murine graft-versus-host (GVH) disease takes two forms depending upon the parental/F1 strain combination employed. Anemia, lymphopenia, hypogammaglobulinemia, profound anti-F1 cytotoxicity, and the loss of cytotoxic potential against third party alloantigen is seen in acute lethal GVH disease. In contrast to this, in chronic GVH disease there is polyclonal B cell activation, auto-antibody production, no anti-F1 cytotoxicity, and retained cytotoxicity against allotargets. We have previously reported that this marked disparity in disease expression results from a radiosensitive host veto cell which protects the F1 mouse from parental anti-F1 cytotoxicity in mice undergoing CGVH disease. This cell could be induced in vitro or in vivo in CGVH disease. Using an in vitro system, we now demonstrate that a CD4(+), radiation-sensitive, T cell does emerge in acute lethal GVH disease which is capable of down-regulating cytotoxicity. The cell does not appear to be a veto cell in that it attenuates cytotoxicity directed against nonself alloantigen. The function of this cell does not appear to be influenced by minor lymphocyte stimulatory gene products. We further report that, in ALGVH disease, regulation by this cell is not readily apparent due to the emergence of a CD8(+) T cell of parental (B6) origin, which opposes its action.

Antimutagenicity of hydrolyzable tannins from Terminalia chebula in Salmonella typhimurium

A tannin fraction (TC-E) from the dried fruit pulp of Terminalia chebula was obtained by successfully extracting with 95% ethyl alcohol and ethyl acetate. TC-E was subjected to silica gel chromatography which yielded four fractions, viz., TC-EI, TC-EII, TC-EIII and TC-EIV. Thin layer chromatography (TLC) and 13C-NMR revealed that TC-EI was gallic acid (GA) derivative while the other fractions were tannin in nature. TC-E and its fractions were evaluated for their antimutagenic potential against two direct-acting mutagens, 4-nitro-o-phenylenediamine (NPD) and 4-nitroquinoline-N-oxide (4NQNO), and S9-dependent mutagen, 2-aminofluorene (2AF) in TA98 and TA100 strains of Salmonella typhimurium. The study revealed that the extract (TC-E) and its fractions were highly significant against S9-dependent mutagen, 2AF. The effect was found to be more or less corresponding with the nature of the fractions, as the monomeric TC-EI (a GA derivative) was least effective as compared to other fractions which were oligomeric, and the order of their effectiveness as per their IbD50 value being TC-EIV (8.9 micrograms)>TC-EIII (17.8 micrograms)>TC-EII (45 micrograms)>TC-EI (320 micrograms) in TA98; TC-EIV being 40 times more effective than TC-EI in inhibiting his+ revertants. A similar effect was noticed in TA100 too, where TC-EI was the least effective and TC-EII had the maximum effect. A similar result was noticed when the antimutagenicity of GA (a monomeric) was compared with tannic acid (TA, an oligomeric). However, chebula tannins were found to be partly effective against NPD but not at all effective against 4NQNO.

Behavioural alterations in rats induced by single prenatal exposure of haloperidol

Haloperidol (50 mg/kg, i.p.) treatment was given once to two different groups of pregnant Charles Foster rats on gestational day 9 and 14, these being respectively the critical periods of neural morphogenesis and rapid neural cell proliferation in this species. Pregnant control rats were similarly treated with equal volume of vehicle. The pups born were subjected to open-field exploratory behaviour and elevated plus-maze behaviour tests of anxiety and learned helplessness test of depression at 9 weeks of age. The results indicate that prenatal haloperidol treatment on gestational day 14 induces a significant increase in open-field ambulation and faecal droppings whereas haloperidol treatment on gestational day 9 caused significantly decreased rearing and unaltered ambulation in rat offsprings. Rat offsprings treated with haloperidol on gestational day 9 and 14 also displayed significant anxiogenic behaviour pattern on elevated plus-maze. Significantly increased number of escape failures were observed in learned helplessness tests indicating presence of depression in haloperidol treated rat offsprings. These behavioural alterations were found to be more marked in rat offsprings treated with haloperidol on gestational day 14. The results suggest that prenatal single exposure of high dose of haloperidol during critical period of neural cell proliferation leaves a lasting imprint on offsprings resulting in abnormal emotional state.

Differences in stratum corneum pH gradient when comparing white Caucasian and black African-American skin

This study assessed pH gradient changes in relation to stratum corneum (SC) depth and possible differences between white caucasian and black African-American skin. Ten white and eight black people entered the study. SC was progressively removed by cellophane tape stripping on the volar forearm and weighed with a microbalance. Transepidermal water loss (TEWL) and SC pH were measured every three tape strippings. Significantly increased TEWL and decreased pH values were found with increasing SC depth in both races. Significantly increased TEWL in black people was found after three and six tape strippings (P < 0.05 and 0.03, respectively); pH was significantly decreased in black people after three tape strippings (P < 0.005). No differences were found between the races after nine, 12 and 15 strippings, i.e. in the deeper SC layers. The data confirm that pH in the superficial SC layers decreases with SC depth; only total SC removal results in increased pH values. In the superficial layers, there are significant differences in both water evaporation and skin pH, possibly explaining the contradictory literature.

A novel method of purifying lung surfactant proteins A and D from the lung lavage of alveolar proteinosis patients and from pooled amniotic fluid

A simple procedure has been developed for the purification of the surfactant proteins SP-A and SP-D from lung lavage of patients with alveolar proteinosis. The SP-D is purified by fractionation of the supernatant obtained after spinning the lavage at 10000 X g for 40 min, while the bulk of the SP-A is purified by fractionation of the pellet. The supernatant is applied to a maltosyl-agarose column and the bound SP-D is specifically eluted using MnCl2. The pellet is solubilised in 6 M urea and, following renaturation, the solubilised proteins are applied to maltosyl-agarose and SP-A eluted using a gradient of EDTA. Both SP-A and SP-D are further purified by gel-filtration on Superose-6. This procedure has also been used to prepare successfully human SP-A and SP-D from amniotic fluid and may be generally applicable to the isolation of these surfactant proteins from lung washings obtained from other species.

Fine-needle aspiration biopsy of colonic masses

Between 1989 and 1996, fine-needle aspiration biopsy was performed in 22 patients with palpable colonic masses. In all of these patients colonoscopic examination was either not possible or could not be carried out successfully. The results of aspiration biopsy were confirmed by surgery and histopathological examination of the tissue. Aspiration biopsy correctly diagnosed all except one case. It identified all cases of colonic cancer. One patient with colonic tuberculosis was also diagnosed correctly. However, in another patient with colonic tuberculosis, aspiration biopsy showed only nonspecific changes in the form of inflammatory and epithelial cells. There were no false-positive results or complications from the procedure. It is concluded that fine-needle aspiration biopsy is a simple, rapid, and accurate method of diagnosing palpable colonic masses in patients in whom a colonoscopy is not possible or cannot be performed satisfactorily.