Structural studies and photochromism of mercury(II)-iodo complexes of (arylazo)imidazoles

Neat reaction between HgI2 and 1-methyl-2-(phenylazo)imidazole (Pai-Me) under microwave irradiation has isolated a novel compound whose structure shows intercalated HgI2 in the layers of Pai-Me. They exist independently in interpenetrated arrays. In a solution phase study, the same reaction has synthesized an iodo-bridged azoimidazole-Hg(II) complex, [Hg(RaaiR')(mu-I)(I)]2 (RaaiR' = 1-alkyl-2-(arylazo)imidazole). The structures have been characterized by X-ray diffraction studies. Chloro-bridged Hg(II) complexes of azoimidazoles, [Hg(RaaiR')(mu-Cl)(Cl)]2, are also known. These complexes upon irradiation with UV light show trans-to-cis isomerization. The reverse transformation, cis-to-trans isomerization, is very slow with visible light irradiation. Quantum yields (phi t-->c) of trans-to-cis isomerization are calculated, and the free ligand shows higher phi than their Hg(II) complexes. The cis-to-trans isomerization is a thermally induced process. The activation energy (Ea) of cis-to-trans isomerization is calculated by controlled temperature reaction. The Ea's of free ligands are much higher than that of halo-bridged Hg(II)-azoimidazole complexes. Chloro-bridged Hg(II) complexes show lower Ea's than those of iodo-bridged complexes. DFT calculation has been adopted to rationalize the experimental results.

The effect of maternal methadone use on the fetal heart pattern: a computerised CTG analysis

Using a computerised analysis, the cardiotocograph (CTG) from women who use methadone (n= 25) when compared with women who do not use methadone (n= 25) showed a significant reduction in the fetal heart baseline rate, with a significant reduction in number of accelerations and episodes of high variation. The short-term variation, number of decelerations and episodes of low variation were not different between the two groups. The time taken to meet the standardised criteria was not different, and it is possible that a computer-assisted CTG analysis could be more accurate than a naked eye interpretation.

Neuroprotective and neurorescue effect of black tea extract in 6-hydroxydopamine-lesioned rat model of Parkinson's disease

In the present study, an attempt has been made to explore the neuroprotective and neuroreparative (neurorescue) effect of black tea extract (BTE) in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD). In the neuroprotective (BTE + 6-OHDA) and neurorescue (6-OHDA + BTE) experiments, the rats were given 1.5% BTE orally prior to and after intrastriatal 6-OHDA lesion respectively. A significant recovery in d-amphetamine induced circling behavior (stereotypy), spontaneous locomotor activity, dopamine (DA)-D2 receptor binding, striatal DA and 3-4 dihydroxy phenyl acetic acid (DOPAC) level, nigral glutathione level, lipid peroxidation, striatal superoxide dismutase and catalase activity, antiapoptotic and proapoptotic protein level was evident in BTE + 6-OHDA and 6-OHDA + BTE groups, as compared to lesioned animals. BTE treatment, either before or after 6-OHDA administration protected the dopaminergic neurons, as evident by significantly higher number of surviving tyrosine hydroxylase immunoreactive (TH-ir) neurons, increased TH protein level and TH mRNA expression in substantia nigra. However, the degree of improvement in motor and neurochemical deficits was more prominent in rats receiving BTE before 6-OHDA. Results suggest that BTE exerts both neuroprotective and neurorescue effects against 6-OHDA-induced degeneration of the nigrostriatal dopaminergic system, suggesting that possibly daily intake of BTE may slow down the PD progression as well as delay the onset of neurodegenerative processes in PD.

Pregnancy outcome in women who use opiates

BACKGROUND

Opiate use in pregnancy is on the increase. There are a number of complications associated with this problem but current data from UK centres are sparse.

DESIGN

A retrospective study.

SETTING

A North of England Hospital.

METHODS

Maternal and neonatal case records were studied and a standard data set completed.

MAIN OUTCOME MEASURES

Maternal and neonatal outcomes were classified by the woman's drug usage at the end of pregnancy.

RESULTS

One hundred and ten babies born to 108 women were studied and 41% had evidence of previous exposure to the hepatitis C virus. Women who took heroin in later pregnancy were significantly more likely than women who were stabilised on methadone to have a baby who needed morphine (40% versus 19%), had higher mean maximum neonatal abstinence scores (NAS) (5.8 versus 4.7) and stayed in the neonatal unit significantly longer (mean 17.2 days versus 11.8 days). There were two neonatal deaths and the overall rate of prematurity was 29%.

CONCLUSIONS

The outcome for pregnancy in women who use opiates is complicated by high rates of prematurity and neonatal death. Women who used heroin in later pregnancy had babies who developed more severe NAS and needed a longer hospital stay than women who used only methadone.

Co-transplantation of carotid body and ventral mesencephalic cells as an alternative approach towards functional restoration in 6-hydroxydopamine-lesioned rats: implications for Parkinson's disease

Exogenous administration of various neurotrophic factors has been shown to protect neurons in animal model of Parkinson's disease (PD). Several attempts are being made to search a tissue source simultaneously expressing many of these neurotrophic factors. Carotid body (CB) contains oxygen-sensitive glomus cells rich in dopamine (DA) and expresses glial cell line-derived neurotrophic factor, brain-derived neurotrophic factor and neurotrophin-3. We have attempted to study the functional restoration following co-transplantation of CB cells and ventral mesencephalic cells (VMC) in a 6-hydroxydopamine-lesioned rat model of PD. A significant recovery (p < 0.001) in d-amphetamine-induced circling behavior (80%) and spontaneous locomotor activity (85%) was evident in co-transplanted animals at 12 weeks post-transplantation as compared to lesioned animals. Similarly, a significant (p < 0.001) restoration was observed in DA-D(2) receptor binding (77%), striatal DA (87%) and 3,4-dihydroxyphenylacetic acid (DOPAC) (85%) levels and nigral DA (75%) and DOPAC (74%) levels. Functional recovery was accompanied by tyrosine hydroxylase (TH) expression and quantification of TH-positive cells by image analysis revealed a significant restoration in TH-immunoreactive (IR) fiber density in striatum, as well as TH-IR neurons in substantia nigra pars compacta in co-transplanted animals over VMC-transplanted animals. The result suggests that co-transplantation of CB cells along with VMC provides better and long-term functional restoration in the rat model of PD, possibly by supporting the survival of newly grafted cells as well as remaining host DA neurons.

Mosquito repellent (pyrethroid‐based) induced dysfunction of blood–brain barrier permeability in developing brain

Pyrethroid-based mosquito repellents (MR) are commonly used to protect humans against mosquito vector. New born babies and children are often exposed to pyrethroids for long periods by the use of liquid vaporizers. Occupational and experimental studies indicate that pyrethroids can cause clinical, biochemical and neurological changes, and that exposure to pyrethroids during organogenesis and early developmental period is especially harmful. The neurotoxicity caused by MR has aroused concern among public regarding their use. In the present study, the effect of exposure of rat pups during early developmental stages to a pyrethroid-based MR (allethrin, 3.6% w/v, 8h per day through inhalation) on blood-brain barrier (BBB) permeability was investigated. Sodium fluororescein (SF) and Evan's blue (EB) were used as micromolecular and macromolecular tracers, respectively. Exposure during prenatal (gestation days 1-20), postnatal (PND1-30) and perinatal (gestation days 1-20 + PND1-30) periods showed significant increase in the brain uptake index (BUI) of SF by 54% (P < 0.01), 70% (P < 0.01), 79% (P < 0.01), respectively. This increase persisted (68%, P < 0.01) even 1 week after withdrawal of exposure (as assessed on PND37). EB did not exhibit significant change in BBB permeability in any of the group. The results suggest that MR inhalation during early prenatal/postnatal/perinatal life may have adverse effects on infants leading to central nervous system (CNS) abnormalities, if a mechanism operates in humans similar to that in rat pups.

Effect of glial cell line‐derived neurotrophic factor (GDNF) co‐transplantation with fetal ventral mesencephalic cells (VMC) on functional restoration in 6‐hydroxydopamine (6‐OHDA) lesioned rat model of Parkinson's disease: neurobehavioral, neurochemical and immunohistochemical studies

Among trophic factors already known, glial cell line-derived neurotrophic factor (GDNF) and other members of its family have potent and specific action on dopaminergic neurons. In the present investigation an attempt has been made to validate the role of GDNF co-transplantation with fetal ventral mesencephalic cells (VMC) on functional viability and restoration using neurobehavioral, neurochemical and immunohistochemical parameters at 6 weeks post-transplantation in 6-hydroxydopamine (6-OHDA) lesioned rat model of Parkinson's disease (PD). A significant restoration (P<0.01) in D-amphetamine induced rotations, spontaneous and apomorphine induced locomotor activity in rats co-transplanted with VMC and GDNF was observed as compared to VMC alone transplanted rats. Level of dopamine (DA), 3,4-dihydroxy-phenyl acetic acid (DOPAC) and dopamine D2 (DA-D2) receptors in the caudate putamen (CPu) were significantly (P<0.001) restored in co-transplanted group as compared to VMC transplanted or GDNF administered animals. The functional viability of transplanted VMC was confirmed by tyrosine hydroxylase (TH) expression and quantification of TH-positive cells by image analysis revealed a significant restoration in TH-IR fibers density as well as TH-IR neurons counts in co-transplanted animals over VMC transplanted animals. Results suggest that co-transplantation of VMC and GDNF may be a better approach towards functional restoration in 6-OHDA lesioned rat model of Parkinson's disease.

Neonatal outcome following maternal opiate use in late pregnancy

OBJECTIVE

To determine the neonatal outcome in the form of use of morphine and triclofos to treat the neonatal abstinence syndrome following maternal opiate use in late pregnancy.

METHODS

Retrospective case study of 51 pregnancies associated with maternal opiate use between January 1992 and December 1997.

RESULTS

There were 51 pregnancies which resulted in 51 live births. In the third trimester 22 women took methadone only, 19 women used heroin and 10 women stopped opiate use during pregnancy. Babies of methadone using mothers were less likely to be treated with morphine or triclofos than heroin using women. Morphine, triclofos use was more common in high dose methadone users compared with low users.

CONCLUSIONS

Successful methadone substitution compared with continued heroin use results in reduced morphine and triclofos use in the babies exposed.