Uniparous female rats were exposed to 10 ppm cadmium (as Cd(CH3COO)2) in drinking water, ad libitum, from day 0 of pregnancy; neonates exposed to Cd gestationally and lactationally were separated from their mothers at 21 days of age and were given 10 ppm Cd in drinking water up to 45 days of age. The sequential analysis of brain lipids during development showed a significant reduction in the total lipid levels at 15, 21, 30 and 45 days of age compared to the respective controls. No change in the triglyceride levels was observed in the Cd-exposed group, except for a slight but statistically significant increase (12%, p < 0.05) at day 15 of postnatal life. Metallic exposure also decreased the cholesterol content of brain at different time intervals in comparison to its levels in age-matched control rats. The analysis of sialic acid content of the total gangliosides revealed elevated levels of this group of glycolipids at 21 (25%), 30 (17%) and 45 (23%) days of age compared to their counterpart controls. However, a remarkable reduction in the concentration of brain galactosylceramide (30-43%) and 3'-sulphogalactosylceramide (24-37%) at 21, 30 and 45 days of age was observed following pre- and postnatal exposure of cadmium in comparison to the respective controls. The ontogenic profile of different brain phospholipids in the Cd-exposed group showed an increase in the levels of phosphatidylethanolamine at 21 (31%), 30 (25%) and 45 (19%) days of age; the phosphatidylcholine contents increased at day 21 (14%), followed by a significant decrease at 30 (14%) and 45 (19%) days compared to age-matched controls. Brain phosphatidylinositol, phosphatidylserine and sphingomyelin did not show any alteration at early periods of exposure but decreased significantly following continued exposure by 34%, 45% and 21%, respectively, at 45 days of age. Metal analysis in the brain showed a reduction in zinc and copper levels at 15 and 21 days of age in Cd-exposed animals; however, iron levels remained comparable with control values throughout the experiment. It may be concluded that an early exposure of Cd may produce alteration in the development of different lipids, which may produce CNS dysfunctions with a possibility of being manifested even in later life.

Acetates↗

PubMedDate not supplied

Effects of neonatal quinalphos exposure and subsequent withdrawal on free radical generation and antioxidative defenses in developing rat brain.

Ten-day-old rat pups were given quinalphos (QP, 0.5 mg kg(-1)) orally up to postnatal days (PND) 21 or 45. A group of rats exposed to QP was withdrawn from the treatment at PND 21 and was killed at PND 45 for the withdrawal study. Acetylcholinesterase decreased in the brain and blood after QP exposure but recovered after withdrawal. Superoxide radical generation in brain was increased by 43%, 59% and 39% following exposure up to PND 21 and 45 and in the withdrawal group, respectively. Quinalphos did not alter hydrogen peroxide formation but increased hydroxyl radical (19%) production at PND 45. Quinalphos elevated the activities of superoxide dismutase by 30%, (although the increase from 0.24 to 0.31 was physiologically not significant) and catalase by 50% at PND 21, which up on withdrawal of the exposure at PND 22 recovered partially or completely at PND 45. However, the continuous exposure up to PND 45 decreased superoxide dismutase (63%) and catalase (31%) activities. Selenium-independent glutathione peroxidase (GPx) was increased at PND 21 (31%) and PND 45 (152%) after QP exposure and there was complete recovery after withdrawal. Selenium-dependent GPx, which was elevated slightly at PND 21, was also normalized after withdrawal. Prolonged exposure to QP did not alter the ascorbic acid content and produced a marked decrease in cerruloplasmin (46%) levels. Brain glutathione levels increased marginally in QP-exposed rats and became normal in the withdrawal group. Quinalphos exposure up to PND 45 enhanced brain lipid peroxidation (28%) and decreased vitamin E levels (15%). It appears that neonatal QP exposure produces cerebral oxidative stress, which may result in deleterious effects on central nervous system function immediately and in later life.

Administration, Oral↗

PubMedDate not supplied

Profile of reactive oxygen species generation and antioxidative mechanisms in the maturing rat kidney.

The antioxidative potential and reactive oxygen species generation were assessed in rat kidney during early critical periods of development and maturation. Superoxide anion generation was found to be low in kidney during early postnatal days of development, whereas hydrogen peroxide levels remained unaltered during development. The levels of thiobarbituric acid reactive substances and protein carbonyls in developing kidney were higher during early postnatal days, up to 26 days after birth, compared to the adult levels. Kidney sulphydryl contents were significantly less during early periods (9 days postnatally) of development compared to adults but attain adult value by postnatal day 26. The levels of ascorbic acid and ceruloplasmin were also higher in developing kidney than in adults. Among enzymic antioxidants, the levels of glutathione peroxidase (GPx) enzyme in developing kidney were high during the early developmental period of the study as compared to adults; however, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were found to be significantly low at early postnatal days up to 16 days of age, which subsequently attained maturational level by the age of 26 days. The levels of antioxidant enzymes and sulphydryl contents in the developing kidney during early periods after birth are low but they increase subsequently with increasing age. Therefore, the present finding suggests that immature kidneys are in a highly dynamic stage of development during the early period and are equipped with antioxidative defence mechanisms that may have a predominant role in protecting against oxidative challenge.

Animals↗

PubMedDate not supplied

Effect of pyrethroid-based liquid mosquito repellent inhalation on the blood-brain barrier function and oxidative damage in selected organs of developing rats.

Pesticides have been implicated in various neurological disorders in humans and experimental animals. Our earlier studies have demonstrated a high vulnerability of developing blood-brain barrier (BBB) towards very low level exposure of quinalphos, cypermethrin and lindane. Earlier it has been observed that a cypermethrin-induced increase in the BBB permeability of neonatal rats was found to be persistent, requiring a longer period of withdrawal for complete recovery. These observations lead us to investigate the effect of a commonly available liquid mosquito repellent (MR) containing a pyrethroid compound, allethrin (3.6% w/v), on the functional integrity of the developing BBB and on certain parameters of oxidative damage in brain, liver and kidney. Two-day-old rat pups were allowed to inhale the MR (18 h per day) for 8 days (postnatal days (PND) 2-9). Rats exposed to MR were further withdrawn from the exposure for 8 days (PND 10-17) to study whether the changes induced following inhalation are reversible. Results of the study have shown a significant increase in the BBB permeability (45%) of the MR-exposed rat pups to a micromolecular tracer, sodium fluorescein (mol. wt. 376), used for the quantitative assessment of the BBB permeability, suggesting a delayed maturity of the BBB system. Brain glutathione (GSH) levels were also decreased (17%) in the exposed individuals. The oxidatively damaged end-products of lipids, measured as lipid hydroperoxides and conjugated dienes, were found to be increased in brain (42%, 16%), liver (34%, 20%) and kidney (68%, 29%), respectively. The oxidative product of protein, measured as protein carbonyls, was also increased significantly in liver (43%) and kidney (16%) of the MR-exposed rat pups as compared to age-matched controls. The biochemical changes that occurred in the BBB permeability and the oxidatively damaged end-products following MR inhalation in neonatal rats were, however, found to be completely recovered except for an increase in brain GSH (28%) level. The results suggest the possibility of health risk due to exposure to pesticide-based mosquito repellents, especially when exposure takes place in individuals at an early age.

Administration, Inhalation↗

PubMedDate not supplied

A 500 MHz proton NMR study of stacking interactions: binding of tripeptide Lys-Tyr-Lys to tetradeoxynucleotide d-GpCpGpC.

The complete sequential assignment and conformation of d-GpCpGpC in D2O has been determined from 1D NMR spectra at 285-320 K and room temperature 2D-COSY and NOESY spectra. The tetradeoxynucleotide exists primarily as a right handed double helix at 285 K, having Tm as 314 K. On binding to a tripeptide Lys-Tyr-Lys in a concentration equimolar to tetranucleotide duplex, the Tyr ring protons shift upfield by 0.14 ppm at 285 K. The increase in Tm on binding suggests stabilization of duplex. The existence of intermolecular NOEs between C4 sugar protons and Tyr alpha C and Lys alpha C protons give direct evidence of proximity of Tyr residue to the C4 base of d-GpCpGpC. The conformation of d-GpCpGpC remains unchanged on binding. The observed results are interpreted in terms of preferential stacking of aromatic ring of Tyr residue with proximal base-pair of d-GpCpGpC, stabilized by electrostatic interaction of Lysine side chains with backbone phosphates. This is in contrast to intercalculation of aromatic dyes within base-pairs resulting in a change in sugar conformation at the binding site.

Amino Acid Sequence↗

PubMedDate not supplied

A framework for querying a database for structural information on 3D images of macromolecules: A web-based query-by-content prototype on the BioImage macromolecular server.

Nowadays we are experiencing a remarkable growth in the number of databases that have become accessible over the Web. However, in a certain number of cases, for example, in the case of BioImage, this information is not of a textual nature, thus posing new challenges in the design of tools to handle these data. In this work, we concentrate on the development of new mechanisms aimed at "querying" these databases of complex data sets by their intrinsic content, rather than by their textual annotations only. We concentrate our efforts on a subset of BioImage containing 3D images (volumes) of biological macromolecules, implementing a first prototype of a "query-by-content" system. In the context of databases of complex data types the term query-by-content makes reference to those data modeling techniques in which user-defined functions aim at "understanding" (to some extent) the informational content of the data sets. In these systems the matching criteria introduced by the user are related to intrinsic features concerning the 3D images themselves, hence, complementing traditional queries by textual key words only. Efficient computational algorithms are required in order to "extract" structural information of the 3D images prior to storing them in the database. Also, easy-to-use interfaces should be implemented in order to obtain feedback from the expert. Our query-by-content prototype is used to construct a concrete query, making use of basic structural features, which are then evaluated over a set of three-dimensional images of biological macromolecules. This experimental implementation can be accessed via the Web at the BioImage server in Madrid, at http://www.bioimage.org/qbc/index.html.

Animals↗

PubMedDate not supplied

Information processing with frequency-dependent synaptic connections.

The efficacy of synaptic transmission between two neurons changes as a function of the history of previous activations of the synaptic connection. This history dependence can be characterized by examining the dependence of transmission on the frequency of stimulation. In this framework synaptic plasticity can also be examined in terms of changes in the frequency dependence of transmission and not merely in terms of synaptic strength which constitutes only a linear scaling mechanism. Recent work shows that the frequency dependence of transmission determines the content of information transmitted between neurons and that synaptic modifications can change the content of information transmitted. Multipatch-clamp recordings revealed that the frequency dependence of transmission is potentially unique for each synaptic connection made by a single axon and that the class of pre-postsynaptic neuron determines the class of frequency dependence (activity independent), while the unique activity relationship between any two neurons could determine the precise values of the parameters within a specific class (activity dependent). The content of information transmitted between neurons is also formalized to provide synaptic transfer functions which can be used to determine the role of the synaptic connection within a network of neurons. It is proposed that deriving synaptic transfer functions is crucial in order to understand the link between synaptic transmission and information processing within networks of neurons and to understand the link between synaptic plasticity and learning and memory.

Algorithms↗

PubMedDate not supplied

Construction of Zn2+/Cd(2+)-tolerant cyanobacteria with a modified metallothionein divergon: further analysis of the function and regulation of smt.

This paper reports the (de novo) construction of mutants of Synechococcus PCC 7942 lacking the repressor (SmtB) of the metallothionein gene, smtA. These smtA+/B- cells are more tolerant to elevated [Zn2+] and [Cd2+] than cells containing an intact metallothionein divergon (smt). Previously selected (by step-wise adaptation) Cd(2+)-tolerant mutants contain additional copies of smtA and possibly other undetected mutations. It is now confirmed that these cells also contain a deletion within 'all' copies of smtB and hence fail to revert to wild type following subculture in medium which has not been supplemented with Cd2+ or Zn2+. Northern analysis showed enhanced accumulation of smtA transcripts, even in the absence of added metal ions in these mutants. An increase in the accumulation of Zn2+ is reported in cells containing an intact metallothionein divergon compared to cells deficient in both smtA and smtB. This supports the assumption that SmtA binds Zn2+ within cyanobacterial cells. We also describe the use of the above mentioned mutants to identify additional factors involved in the regulation of transcription from the smtA operator-promoter.

Bacterial Proteins↗

PubMedDate not supplied

Breast feeding practices in Jalandhar.

Explore the source record for details and available documents.

Breast Feeding↗

PubMedDate not supplied

Management of anorectal malformation in neonates.

Anorectal malformations are one of the commonest anomalies in the new born. Major advances have been made in the last decade in operative techniques to reconstruct this abnormality. The final outcome in these babies is dependent on careful planning and operative intervention in the neonatal period. The purpose of this paper is to discuss the varied presentations of this anomaly, initial assessment and operative management with reference to our own experience.

Female↗