Species identification of clinically important Aeromonas spp. by restriction fragment length polymorphism of 16S rDNA

AIMS

The aim of the study was to characterize 16S rDNA of Aeromonas spp. to rapidly identify clinically important species of these bacteria.

METHODS AND RESULTS

Sequence analysis of published 16S rDNA for unique restriction sites revealed prospect of species identification. Extraction of genomic DNA followed by amplification and step-by-step restriction endonuclease digestion of 16S rDNA was able to identify Aeromonas spp. of medical significance. Validation of the method was performed by subjecting 53 Aeromonas strains of multiple origin to similar treatment. Results of the study were in agreement with corresponding species of the isolates.

CONCLUSIONS

The method developed offers an easily interpretable tool for the identification of Aeromonas spp. of clinical relevance.

SIGNIFICANCE AND IMPACT OF THE STUDY

The developed methodology should facilitate routine laboratory diagnosis of Aeromonas spp. from clinical cases to species level.

Comparative study of cytotoxicity of Aeromonas spp. on four different cell lines

In vitro cytotoxicity is an important virulence property of motile mesophilic Aeromonas species. Cell-free supernatant prepared from 55 Aeromonas isolates including one A. hydrophila type strain (MTCC 646) were examined for their cytotoxic potential on four different cell lines (Vero, BHK-21, MDBK, B 95a). Results of the study revealed cytotoxic potential in 92.72% of the isolates. Analysis of data exposed significant variation among isolates in respect of their cytotoxicity. Vero cells proved to be most sensitive to aeromonal toxins and B 95a cells showed significantly (P<0.01) lower response compared to other cell lines. Sensitivities of BHK-21 and MDBK cell lines were in between Vero and B 95a.

Effects of dimecron on developing chick embryo: malformations and other histopathological changes

The effect of dimecron, an organophosphorus insecticide, on developmental alterations and histopathological damage was determined in the developing chick embryo. The insecticide was administered at two different doses (25 microg and 35 microg) into the egg yolk through a pore into the equatorial region at day 0 of incubation. Significant abnormalities in relation to organogenesis and overall retardation in growth were noted in the insecticide-treated embryos. Histopathological study of the treated whole embryo showed abnormal features in the formation of different vital organs. The liver and kidney were severely affected by the pesticide at both doses. Based upon these findings it may be concluded that dimecron does play a role in producing embryotoxicity at different stages of embryogenesis.

Prednisolone-induced alteration in hepatic and muscular protein and glycogen level: its correlation with blood glucose level in mice

Prednisolone, a potent glucocorticoid, is well known for its immunosuppressive effects on animals. A single dose of 100 microg, 200 microg and 300 microg prednisolone/kg body weight was administered in Swiss albino male mice. Seven days after treatment, the animals were sacrificed to investigate the effect of prednisolone on hepatic and muscular protein contents and glycogen levels along with the level of blood glucose. A catabolic effect on the protein level was evidenced but at the same time the mice became hypoglycemic.

Zoonoses and bats: a look from human health viewpoint

Bats are the most abundant and most widely distributed mammals on the Earth after humans. Except Antarctica and some small remote islands, they are prevalent worldwide. Although the actual role played by bats as reservoir or in disseminating zoonoses is still enigmatic a multitude of zoonotic diseases are known to be associated with bats. Such diseases including viral, bacterial, parasitic, fungal and rickettsial diseases, reported from all over the world including India have been briefed in this article as an informative approach because dramatically increased and diversified human activities during the last few decades perturbing natural ecosystems are enough to compel public health personnel to have an investigative look at these flying mammals.

Isolation of verotoxin producing Escherichia coli from diarrhoeal and urinary tract infection patients

Fourty nine Escherichia coli strains, isolated from diarrhoeal and urinary tract infection (UTI) patients, attending Bareilly district hospital, Uttar Pradesh during October to December, 1998 were screened for verotoxin (VT) production by Vero cell assay. Five strains produced characteristic cytopathic effect on Vero cell line, of which 4 were from diarrhoeal and one was from UTI-patient. The level of VT-production varied widely. Antibiotic sensitivity tests revealed that the VT-producing E. coli (VTEC) were mostly sensitive to kanamycin, norfloxacin and nalidixic acid but resistant to ampicillin and tetracycline.

Prediction of complement-inhibitory activity of benzamidines using topological and geometric parameters

A hierarchical approach to quantitative structure-activity relationship (QSAR) modeling has been used to estimate the complement-inhibitory potency of 105 benzamidines. This hierarchical approach uses topostructural, topochemical, and geometric parameters in a stepwise fashion to build increasingly more complex models. The results show that topostructural indices alone, specifically I(D), predict inhibitory potency reasonably well. The addition of topochemical and geometrical parameters to the set of descriptors provides only marginal improvement in predictive power. However, when taken alone, the geometric parameter (3D)W provides a more stable model than the topostructural one.

Lack of association between enhanced TRPM-2/clusterin expression and increased apoptotic activity in sex-hormone-induced prostatic dysplasia of the Noble rat

Although the functional role of TRPM-2/clusterin in the prostate remains controversial, it has been postulated that transcriptional activation of the gene is an important mechanism in castration-induced prostatic involution and perhaps is a means for prostatic cells to escape apoptotic induction. In the present study, we have measured expression levels of TRPM-2/clusterin and apoptotic activities in the prostates of castrated Noble (NBL) rats and those treated with testosterone (T) and estradiol-17beta (E2) for 16 weeks. We have previously shown that the combined sex hormone treatment (T+E2) induces dysplasia, a purported preneoplastic lesion, exclusively in the dorsolateral prostates (DLPs) of all treated rats. In the present study, we demonstrate that, as expected, castration readily induced enhanced TRPM-2/clusterin expression, which was accompanied by increased apoptotic activity in the epithelia of DLP and ventral prostate (VP). The increase in TRPM-2/clusterin expression appeared earlier and was more dramatic in the VP than in the DLP. In sharp contrast, treatment of rats with T+E2 for 16 weeks induced augmentation of TRPM-2/clusterin expression selectively in the dysplastic lesions of the DLP but not in the lesion-free VP. The enhanced expression of TRPM-2/clusterin in the dysplastic epithelium was, however, not attended by an increase in apoptotic activity within the lesion. Thus, the observed up-regulation of TRPM-2/clusterin expression in the dysplastic foci of T+E2-treated rats occurred in animals whose androgen status remained normal and, despite the increased level of expression of this gene, apoptotic activity in these lesions was unchanged from basal values measured in the DLPs of untreated rats. These findings suggest that TRPM-2/clusterin expression in dysplastic lesions was no longer repressed by androgen nor was it associated with apoptosis. We propose that overexpression of the gene is likely a phenotype of neoplastic transformation. In addition, we speculate that TRPM-2/clusterin may serve as a survival factor, which could favor accumulation of transformed cells in dysplastic foci and thus promote the carcinogenic process.

Expression and regulation of metallothionein mRNA levels in the prostates of noble rats: lack of expression in the ventral prostate and regulation by sex hormones in the dorsolateral prostate

The rat prostate is composed of two anatomically well-defined regions designated as the ventral prostate (VP) and the dorsolateral prostate (DLP). VP and DLP are known to exhibit marked cytological, biochemical, and functional differences including differential susceptibilities to carcinogens. While the VP is uniquely susceptible to cadmium carcinogenicity [1,2], the DLP is sensitive to sex hormone-induced cancer [3,4]. The role played by the heavy metal binding protein, metallothionein (MT), in the prostate is largely unknown. It is still controversial as to whether MT is expressed in the rat gland. The aim of the present study is to examine the expression pattern of MT mRNA in the rat gland and its probable regulation by heavy metal ions and sex hormones, in order to gain insight into the biological function of MT in the prostate. Northern hybridization and reverse transcriptase-polymerase chain reaction analyses revealed constitutive expression of MT mRNA in the DLP and a lack of expression of the transcript in the VP. In situ hybridization localized the transcript to the epithelium of the DLP, with the lateral prostate epithelium exhibiting the highest level of expression. Administration of cadmium and zinc failed to induce MT transcription in the VP, nor were these treatments effective in elevating levels of MT mRNA in the DLP. A 60% reduction in MT message levels was observed in the DLP following orchiectomy. MT transcript levels in the DLPs of castrates were restored by readministration of androgen to the animals. Long-term treatments (16 weeks) of rats with estradiol-17 beta (E2) or testosterone (T) plus E2 induced a 2.8-fold and a 5-fold increase in MT message content in the DLP, respectively. In sum, MT mRNA was shown to be absent in the VP and was not inducible by heavy metal ions or hormones in this prostatic lobe. These findings substantiate the belief that MT plays a role in heavy metal detoxification and deficiency in its expression may contribute to the unique susceptibility of the VP to cadmium carcinogenicity. By contrast, constitutive expression of MT was demonstrated in the DLP, which was shown to be regulated by androgen and not by exogenously administered heavy metal ions. These results suggest a participatory role of MT in the normal functioning of the DLP. The fact that high levels of MT mRNA were induced in the DLP following long-term estrogenic or conjoint androgenic-estrogenic action alludes to the possibility that MT may serve as an intracellular antioxidant in DLP cells.

Age-related changes in the activities of antioxidant enzymes and lipid peroxidation status in ventral and dorsolateral prostate lobes of noble rats

In this investigation, the activities of five enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-dehydrogenase) involved in oxygen radical (OR)-detoxification and antioxidative defense were measured in conjunction with an index of lipid peroxidation in major prostatic lobes of young (2 month-old) and old (9 month-old) rats. Selective decreases in catalase and glutathione peroxidase activities were observed in the ventral prostate lobe (VP), while a general decline in the activities of all five enzymes studied was noted in the dorsolateral prostate lobes (DLPs) of senescent rats. The extent of lipid peroxidation, measured as concentrations of thiobarbituric acid-reactive products, was greatly elevated in both VP and DLP of old rats. These results demonstrate for the first time that reduction in antioxidant capacity and elevation in peroxidative damage occur in rat prostate during aging. aging. We postulate that these prooxidative alterations promote diseases in the aging prostate.

A note on migration with borrowing constraints

"This note examines an important conflict between the theory and evidence on migration in LDCs. While the Harris-Todaro class of models explain the phenomenon of migration mainly by expected income differential between the economically advanced and the backward regions, the actual evidence in some cases suggests that migration could actually rise following a rise in income in backward areas. We resolve this puzzle by analysing migration in the context of the existence of imperfect credit markets in LDCs. We show that under certain plausible conditions, the rate of migration from the rural to the urban areas may actually rise when rural wages rise, as they ease the constraints on borrowing by potential migrants."

Cyclic AMP level in red blood cells of Plasmodium berghei-infected Mastomys natalensis

The present report describes the changes in cyclic AMP level which occur upon parasitization of red cells by Plasmodium berghei. Parasitized erythrocytes were separated from the non-parasitized population by percoll density-gradient centrifugation. An increase in the cyclic AMP content of both non-parasitized and parasitized erythrocytes of infected animals compared with that of uninfected animals was observed. The patterns of physiological response to isoproterenol in normal, parasitized and non-parasitized erythrocytes were identical.

Polyamine metabolism in some helminth parasites

Polyamine levels of some helminth parasites were analyzed by reverse phase HPLC of benzoyl derivatives. Setaria cervi, Acanthocheilonema viteae, Hymenolepis nana, H. diminuta, and Ascaridia galli contained higher levels of spermine than spermidine while in Ancylostoma ceylanicum and Nippostrongylus brasiliensis the spermidine levels were higher than spermine; putrescine was either absent or present in minor quantities. The enzymes of polyamine biosynthesis viz., ornithine decarboxylase, S-adenosyl methionine (SAM)-decarboxylase, and arginine decarboxylase were present in very low to negligible amounts in all the parasites examined. A. ceylanicum exhibited high activity of ornithine amino transferase (OAT) and catalyzed appreciable decarboxylation of ornithine. The ornithine decarboxylating activity of A. ceylanicum was localized in the particulate fraction containing mitochondria, not inhibited by alpha-difluoromethyl ornithine, the specific inhibitor of ornithine decarboxylase (ODC), but inhibited in the presence of glutamate, suggesting the involvement of mitochondrial OAT rather than a true ODC in ornithine decarboxylation in this parasite. Significant activity of polyamine oxidase was also detected in helminth parasites. The absence of polyamine biosynthesizing enzymes in helminth parasites suggests their dependence on hosts for uptake and interconversion of polyamines, providing a potential target for chemotherapy.

Biogenic amines, metabolites and monoamine oxidase in the filarial worm Setaria cervi

Analysis of biogenic monoamines and their metabolites in Setaria cervi adults by reverse phase high performance liquid chromatography (HPLC) revealed dopamine as the major monoamine followed by norepinephrine and 5-hydroxytryptamine (5-HT). 5-Hydroxy indole acetic acid and tryptophan were also detected in significant amounts. A particulate-bound monoamine oxidase (MAO, EC 1.4.3.4.) catalysing the oxidative deamination of several amines was also demonstrated in both microfilariae and adults. The enzyme from the parasites exhibited unusually high Km values for various monoamines. Dopamine was oxidized at the maximum rate while putrescine was not utilized as the substrate. MAO was predominantly associated with the mitochondrial fraction and concentrated mainly in the cuticle-muscle-hypodermis layer of the filariid. The enzyme was most active around pH 7.5 and 37 +/- 2 degrees C, relatively stable in the frozen state but was thermolabile. The specific MAO inhibitors, clorgyline and deprenyl, inhibited the enzyme with Ki values of 2 x 10(-7) M and 5 x 10(-6) M, respectively. Diethylcarbamazine, suramin, levamisole and centperazine significantly inhibited MAO activity. (The characteristics of the enzyme indicated that it may have a role in host-parasite interactions).

Enzymes of PEP-succinate pathway in Setaria cervi and effect of anthelmintic drugs

Localization of different enzymes of PEP-succinate pathway has been done in Setaria cervi, a bovine filarial worm. Succinate dehydrogenase and fumarate reductase were localized in mitochondria rich particulate fraction while all other enzymes were cytosolic. The in vitro effect of certain antifilarial/anthelmintic agents on these enzymes was also investigated. Sumarmin, at low concentration, could cause a marked inhibition of most of the enzymes of this pathway. Centperazine, an antifilarial drug being developed by CDRI showed significant inhibitory action on pyruvate kinase, lactate dehydrogenase, fumarase and succinate dehydrogenase while CDRI compound 72/70 showed significant inhibition of PEP-carboxykinase activity. Diethylcarbamazine and levamisole, however, were found to be more or less ineffective at lower concentrations against all the enzymes of this pathway.

Hepatic microsomal cytochrome P450 system during experimental hookworm infection

Experimental infection of golden hamsters with the hookworm, Ancylostoma ceylanicum, caused a profound decline in the hepatic microsomal cytochrome P450 content. Concomitant decrease was also noticed in aminopyrine N-demethylase and benzo[a]pyrene hydroxylase activities. However, aniline hydroxylase activity was only marginally elevated during the infection. Microsomal markers, viz., cytochrome b5, NADH-cytochrome-c reductase, and glucose-6-phosphatase, were not significantly altered. Hepatic tissue exhibited an accumulation of lipids, especially phospholipids, triglycerides, and cholesterol, resulting in fatty necrosis around the central vein region. Isolated hepatic microsomes showed a decrease in phosphatidylcholine content. Impairment in hepatic mixed function oxidase (MFO) activities was further confirmed by prolongation in hexobarbital sleeping time and zoxazolamine-induced paralysis. The hepatic MFO system of A. ceylanicum-infected hamsters responded qualitatively and quantitatively in a manner similar to that of control hamsters, upon stimulation with selective chemical inducers like phenobarbitone and 3-methylcholanthrene. Kinetic and in vitro substrate binding studies revealed that for aminopyrine the substrate affinity and the maximum enzyme activity (Vmax) were decreased, while for aniline the binding affinity was decreased and the binding capacity was enhanced. Results indicate specific/selective impairment of the hepatic microsomal cytochrome P450 system during hookworm infection and may have many practical implications in toxicology and pharmacology.

Effect of anthelmintics and phenothiazines on adenosine 5'-triphosphatases of filarial parasite Setaria cervi

S. cervi showed particulate bound Ca2+ ATPase and Na+,K(+)-ATPase activities while Mg2+ ATPase was detected in traces. ATPase of S. cervi was also differentiated from the nonspecific p-nitrophenyl phosphatase activity. Female parasite and microfilariae exhibited higher Ca2+ ATPase and Na+,K(+)-ATPase activities than the male adults and the enzyme Na+,K(+)-ATPase was mainly concentrated in the gastrointestinal tract of the filarial parasite. Na+,K(+)-ATPase of the filariid was ouabain-sensitive while Ca2(+)-ATPase activity was regulated by concentration of Ca2+ ions and inhibited by EGTA. Phenothiazines, viz. trifluoperazine, promethazine and chlorpromazine caused significant inhibition of Ca2+ ATPase and Na+,K(+)-ATPase. Diethylcarbamazine was a potent inhibitor of these ATPases. Mebendazole, levamisole and centperazine also caused significant inhibition of the ATPases indicating this enzyme system as a common target for the action of anthelmintic drugs.

Selective strain distribution pattern of a germline VH gene for a pathogenic anti-DNA autoantibody family

Autoimmune NZB mice rarely develop nephritis, but the SNF1, progeny of Crosses between NZB and the normal SWR strain uniformly develop severe lupus nephritis, indicating that the normal SWR strain makes a genetic contribution to the development of nephritis. The SNF1 mice produce a select population of cationic IgG anti-DNA autoantibodies that share a recurrent cross-reactive idiotype called Id564 and these autoantibodies play a prominent role in the development of nephritis. These pathogenic autoantibodies of SNF1 possess the IgCH allotype of the SWR, indicating their origin from the normal parent. The leader-VH sequences of these Id564+ pathogenic anti-DNA autoantibodies are highly homologous and they are also related by 95% homology to a germline gene of normal C57BL/6 mice, called VH-23, that is a member of an anti-NP antibody gene family. Herein, we cloned the flanking and coding regions of the expressed VHDJH genes of the anti-DNA mAb 564, the prototype member of the pathogenic Id564 family. By restriction analysis and partial sequencing, we found that the VH564 gene is related but distinct in its 5' flanking region from all of the known anti-NP VH genes of C57BL/6 and BALB/c mice. Hybridization with four probes complementary to different segments of the flanking and coding regions of the expressed VH564 gene indicated that the germline gene for VH564 is contained in an approximately 5.2 kb EcoRI fragment of SWR genomic DNA. Moreover, high stringency hybridization with oligonucleotide probes complementary to unique CDR2 and 5' flanking sequences of the expressed VH564 gene revealed that the 'approximately 5.2 kb' germline allele for VH564 that is possessed by the normal SWR parental strain is lacking in the NZB parental strain. C57BL/6 mice also lack this allele of the anti-DNA VH564 germline gene, although this strain possesses the highly homologous, anti-NP-related VH-23 germline gene. Thus germline VH genes for certain pathogenic autoantibodies may have a selective strain distribution pattern.

Effect of thiabendazole & mebendazole on in vitro metabolism of Nippostrongylus brasiliensis adults

Mebendazole and thiabendazole were found to inhibit glucose uptake and its metabolism in the adult rat hookworm (N. brasiliensis) in vitro. Rates of endogenous glycogen utilisation, and excretion of one of the end products of glycolysis viz., lactic acid, were found to be increased, when the intact N. brasiliensis adults were incubated for 60 min with mebendazole and thiabendazole, respectively.

Polyamine metabolism in Ancylostoma ceylanicum and Nippostrongylus brasiliensis

Spermidine was detected as the major polyamine of Ancylostoma ceylanicum as well as Nippostrongylus brasiliensis. Spermine was present in lower amounts whereas the level of putrescine was even less. S-Adenosylmethionine decarboxylase, a rate-limiting enzyme in the biosynthetic pathway of polyamines, was demonstrated at low levels in both parasites. Decarboxylation of lysine and arginine was absent or negligible and that of ornithine questionable, as the enzyme activity was not inhibited by alpha-difluoromethylornithine while RMI 71,645, an irreversible inhibitor of ornithine aminotransferase, strongly inhibited the liberation of CO2 from ornithine. High activity of ornithine aminotransferase was observed in both the parasites and may interfere with the assay for ornithine decarboxylase. Adults of A. ceylanicum were found to rapidly take up spermidine and spermine from incubation medium while uptake of putrescine was very low. These results indicate that hookworms depend on uptake and interconversion rather than de novo synthesis for their polyamine requirement.

Comparative analysis of surface components of adult, micro-filariae and infective larvae of Brugia malayi

A comparative analysis of surface proteins of adult, microfilariae and infective larvae of Brugia malayi, the human filarial parasite, has been carried out using IODOGEN (1,3,4,6-tetrachloro-3,alpha 6 alpha-diphenyl-glycoluril) and lactoperoxidase methods. SDS-polyacrylamide gel electrophoretic and autoradiographic analyses revealed the presence of 9 proteins (15-200 kDa) in adults, while microfilariae and infective larvae showed 8 and 6 proteins (15-120 kDa), respectively. The pattern of proteins radiolabelled by IODOGEN method was very similar to that of proteins labelled by the lactoperoxidase method. Since these proteins are released by the protease treatment of whole parasites, they are likely to be present on the surface of the parasite.

Polyamine metabolism in Setaria cervi, the bovine filarial worm

Spermine and spermidine were found to be the principal polyamines in the bovine filarial parasite Setaria cervi, whereas putrescine was observed in very low amounts. Studies conducted on the enzymes of polyamine biosynthesis revealed low activity for S-adenosyl-methionine decarboxylase, questionable and negligible activities for the decarboxylation of ornithine and arginine, and appreciable activity for ornithine aminotransferase. Uptake studies with radiolabeled putrescine, spermidine and spermine showed that these amines are rapidly taken up from the medium by an active uptake process. The uptake was temperature-sensitive and abolished at 0-4 degrees C. The questionable presence of biosynthetic enzymes such as ornithine and arginine decarboxylase and, on the other hand, an effective uptake mechanism indicate that the parasite may depend on the host for its polyamine requirement, thereby indicating a possible target for chemotherapy.