Methamphetamine generates peroxynitrite and produces dopaminergic neurotoxicity in mice: protective effects of peroxynitrite decomposition catalyst

Methamphetamine (METH)-induced dopaminergic neurotoxicity is believed to be produced by oxidative stress and free radical generation. The present study was undertaken to investigate if METH generates peroxynitrite and produces dopaminergic neurotoxicity. We also investigated if this generation of peroxynitrite can be blocked by a selective peroxynitrite decomposition catalyst, 5, 10,15, 20-tetrakis(N-methyl-4'-pyridyl)porphyrinato iron III (FeTMPyP) and protect against METH-induced dopaminergic neurotoxicity. Administration of METH resulted in the significant formation of 3-nitrotyrosine (3-NT), an in vivo marker of peroxynitrite generation, in the striatum and also caused a significant increase in the body temperature. METH injection also caused a significant decrease in the concentration of dopamine (DA), 3, 4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) by 76%, 53% and 40%, respectively, in the striatum compared with the control group. Treatment with FeTMPyP blocked the formation of 3-NT by 66% when compared with the METH group. FeTMPyP treatment also provided significant protection against the METH-induced hyperthermia and depletion of DA, DOPAC and HVA. Administration of FeTMPyP alone neither resulted in 3-NT formation nor had any significant effect on DA or its metabolite concentrations. These findings indicate that peroxynitrite plays a role in METH-induced dopaminergic neurotoxicity and also suggests that peroxynitrite decomposition catalysts may be beneficial for the management of psychostimulant abuse.

Selenium, an antioxidant, protects against methamphetamine-induced dopaminergic neurotoxicity

Dopaminergic changes were studied in the caudate nucleus of adult female mice after pre- and post-treatment with an antioxidant, selenium, 72 h after the multiple injections of methamphetamine (METH, 4x10 mg/kg, i.p. at 2-h interval) or an equivalent volume of saline. Selenium treatment prevented the depletion of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in caudate nucleus resulting from the METH treatment. These data suggest that METH-induced neurotoxicity is mediated by free radical and selenium plays a protective role against METH-induced dopaminergic neurotoxicity.

Ketamine infusion for postoperative analgesia: a prospective cohort study in asthmatics

Ketamine, most often used as an anaesthetic agent can provide adequate post operative analgesia when delivered in the form of infusion, replacing narcotics, which can cause bronchospasm in susceptible individuals. This cohort study was undertaken to assess the feasibility of providing complete post operative analgesia in asthmatics with ketamine delivered in sub-anaesthetic doses (6.10-6.41 ugm./kg.-1/min-1). Diazepam (0.97-1.02 ugm./kg.-1/min-1) was delivered from the same infusion to eliminate the unwanted effects of ketamine. Ketamine induced little alteration in blood pressure while tachycardia was significant (P < 0.05). Respiratory functions observed, were favourable for asthmatics. Diazepam helped in reducing ketamine induced side effects, but after infusion over long periods tendency of cumulation was observed. Complications encountered were minimum with more than 93% patient acceptability for this method of analgesia.

Ketamine infusion for postoperative analgesia in asthmatics: a comparison with intermittent meperidine

Narcotics commonly used for postoperative analgesia may release histamine and cause bronchospasm in asthmatics. Ketamine, on the other hand, provides analgesia and has the additional advantage of preventing and relieving bronchospasm. We therefore delivered subanesthetic doses of ketamine in combination with midazolam (5.88-6.42 micrograms.kg-1.min-1 and 1.17-1.28 micrograms.kg-1.min-1, respectively), via an infusion for postoperative analgesia after elective abdominal hysterectomy in patients with asthma. Data were compared with those from a similar group of patients receiving conventional intramuscular meperidine. A significant degree and earlier onset of analgesia (P < 0.05) was achieved in the ketamine group. For other variables no significant difference was observed between the groups (P > 0.05). Ketamine-midazolam infusion can thus provide a safe alternative to the usual parenteral narcotic therapy in asthmatics, in terms of analgesia and patient acceptability.

Inhibition of rat brain prostaglandin D synthase by inorganic selenocompounds

Various inorganic selenocompounds dose-dependently inhibited the rat brain prostaglandin (PG) D synthase, both in the purified enzyme preparation and in the crude brain supernatant. All of the quadrivalent selenium compounds tested had a very limited range of IC50 values in the purified enzyme (11-12 microM) and in the brain supernatant (9-15 microM). A divalent selenium compound was also inhibitory, but a hexavalent selenium compound was ineffective. In contrast, organic selenocompounds such as selenomethionine and selenourea had no effect on the PGD synthase activity. Furthermore, sodium sulfate and sodium sulfite up to 10 mM did not inhibit the activity. The inhibition by selenium required the preincubation of the metal with sulfhydryl compounds such as dithiothreitol (DTT), indicating that the formation of selenotrisulfide or some other adduct(s) is essential for the inhibition. Furthermore, the inhibition was reversed by an excess amount of dithiothreitol, suggesting that the selenotrisulfide derivative of DTT binds to the SH group of the PGD synthase. The kinetic analysis revealed the inhibition by selenite to be noncompetitive with a Ki value of 10.1 microM. On the other hand, glutathione-dependent PGD synthase from rat spleen was much less inhibited, and PGF synthase and PGD2 11-ketoreductase activities were not inhibited by the selenium compound.

The use of soap and water in two Bangladeshi communities: implications for the transmission of diarrhea

Efforts to reduce the incidence of diarrheal infections in which enteropathogens are endemic have focused on education about the importance of hand washing to interrupt transmission of such organisms. Since the effectiveness of health education depends on an understanding of the recipients' ideas and customs, we studied perceptions of cleanliness and the role of soap and hand washing in two poor Bangladeshi communities, one rural and one urban. We found that ideas about cleanliness generally are not based on germ theory; cleanliness is viewed in a larger, socioreligious context of purity vs. impurity. Washing serves both physical and spiritual needs and is performed according to defined patterns that may not effectively interrupt transmission of microorganisms. Soap is regarded as a cosmetic rather than an agent for removal of microorganisms.

Inhibition of rat brain prostaglandin D synthase by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

The effect of lovastatin, simvastatin and pravastatin, which are competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, was tested on PGD synthase purified to apparent homogeneity from the rat brain. Lovastatin and simvastatin, which reportedly cause insomnia in vivo, inhibited the PGD synthase activity dose-dependently and showed an IC50 value of 100 and 75 microM, respectively. On the other hand, pravastatin, which does not cause insomnia, showed no significant effect at 100 microM and only a slight effect up to 500 microM.

A particle concentration fluorescence immunoassay for prostaglandin D synthase in the rat central nervous system

A solid phase, particle concentration fluorescence immunoassay (PCFIA) was developed for the measurement of prostaglandin (PG) D synthase in the 100,000g supernatant of various regions of the rat central nervous system. In this assay, the enzyme (in the range of 1-25 micrograms protein of brain supernatant or 1-100 ng of the purified enzyme) is attached to submicrometer carboxypolystyrene beads coated with polyclonal anti-rat brain PGD synthase IgG. The total particle-bound enzyme is assayed with fluorescein isothiocyanate (FITC)-conjugated monoclonal anti-PGD synthase IgG after incubation for 1 h. The optimum assay condition was obtained when carboxyl particles coated with ca. 500 micrograms/ml of polyclonal IgG at pH 5.0 and 5 micrograms/ml of FITC-IgG were used. No significant fluorescence was observed when FITC conjugates or carboxyl particles were prepared using IgG from nonimmunized rabbits. Heat treatment of the brain supernatant decreased the specific binding of the enzyme in parallel with the loss of enzyme activity, indicating that the denatured enzyme is not recognized by this assay method. The PGD synthase immunoreactivity was widely distributed in the brain regions and was highest in the paraflocculus. Although slight discrepancy was observed between the concentration by PCFIA and the enzyme activity measured by using [14C]PGH2 in some brain regions, there is a considerable correlation (0.727) between the values by both methods in the same brain regions. The PCFIA now developed showed higher sensitivity (around 10 times), greater reliability, and larger number of samples measurable at once than the radio-TLC assay using [14C]PGH2. This method could provide valuable information concerning the regulatory mechanisms of PGD synthase.

ADP-ribosylation of highly purified rat brain mitochondria

Highly purified synaptic and nonsynaptic mitochondria were prepared from rat brain, and their ADP-ribosyl transferase and NAD glycohydrolase activities were investigated. Data show that there is no significant difference in ADP-ribosyl transferase activity between these two types of subcellular preparations. However, NAD glycohydrolase activity appeared to be much higher in nonsynaptic mitochondria. The specific activity of both enzymes was investigated in the presence of the inhibitor nicotinamide or its analogue 3-aminobenzamide or other adenine nucleotides, such as ATP or ADP-ribose. The inhibitory effect of nicotinamide or 3-aminobenzamide on ADP-ribosyl transferase appears rather weak compared with their effect on NAD glycohydrolase activity. However, ADP-ribose and ATP appeared more effective in inhibiting ADP-ribosyl transferase. Our results provide evidence for the existence of ADP-ribosyl transferase activity in rat brain mitochondria. When NAD glycohydrolase was inhibited totally by nicotinamide, the transfer of ADP-ribose from NAD to mitochondrial proteins still occurred. The chain length determinations show that the linkage of ADP-ribose to mitochondrial proteins is oligomeric.

Isolation and estimation of gangliosides in discrete regions of the forebrain: effects of estrogen on regional lipid profiles

The main aim of the present study was to evaluate the neurochemical changes in the levels of gangliosides, total lipids, phospholipids, cholesterol, esterified fatty acids and triglyceride of the hypothalamus, hippocampus, amygdaloid nucleus, midline nuclei of thalamus, gyrus cinguli and olfactory bulbs following the intramuscular administration of ethinylestradiol (100 mcg) to each female rabbit daily for 30 days. Remarkable increment in the concentration of gangliosides was discernible in hippocampus, amygdaloid nucleus and olfactory bulbs. Interestingly, these levels showed significant decrement in the hypothalamus. The contents of total lipids, triglyceride and esterified fatty acids exhibited significant decrease in the hypothalamus. On the other hand, these levels showed a remarkable increment in olfactory bulbs with a significant elevation in the levels of phospholipids. The concentration of phospholipids was, however, markedly depleted in amygdaloid nucleus. The contents of esterified fatty acids exhibited decrement in hippocampus but the midline nuclei of thalamus showed increment. A significant elevation was also discernible in the levels of triglyceride in gyrus cinguli. The results suggest that the lipid contents are affected differentially in the various parts of the brain.

Organophosphate metasystox-induced increment of lipase activity and lipid peroxidation in cerebral hemisphere: diminution of lipids in discrete areas of the rat brain

The effects of the pesticide, metasystox (O,O-dimethyl-S-2 or Metasystor (ethylsulphinyl) ethylthiophosphate), on various lipid fractions in the discrete areas of the brain were studied. The daily intraperitoneal administration of 4 mg/kg body weight of metasystox for 10 days has depleted the levels of total lipids, phospholipids, cholesterol, esterified fatty acids and gangliosides in cerebral hemisphere, cerebellum, brain stem and spinal cord. But the lipase and lipid peroxidation measured in the cerebral hemisphere were significantly increased. It is possible that the inhibition of the lipid levels in the discrete areas of the brain may be due to the increase activity of lipase and lipid peroxidation.

Microanalysis of lipids in discrete brain areas of the rabbit following intramuscular administration of steroid contraceptive

The effects of 60- and 90-day administration of a pill containing 0.05 mg ethinylestradiol and 0.5 mg norgestrel on the regional lipid levels of female albino rabbit brains have been investigated. Decreased levels of total lipids, phospholipids, cholesterol, free fatty acids and esterified fatty acids were observed in hypothalamus, hippocampus, amygadaloid nucleus, midline nuclei of thalamus and gyrus cinguli. However, the levels of esterified fatty acids only in the amygdaloid nucleus and that of cholesterol in hypothalamus were significantly increased.

Early detection of cervical intraepithelial lesions by simple visual inspection after acetic acid among women in Rajshahi medical college hospital

Aim: To evaluate the performance of visual inspection of acetic acid (VIA) in the detection of precancerous and early cancerous lesions of cervix. Materials and methods: Total 5593 eligible women who randomly came to the Gyenae out patient department (OPD) of RMCH (Rajshahi Medical College Hospital) were examined by VIA. Detection of well defined, opaque, acetowhite lesions close to the squamocolumner junction or in transitional zone or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA. Those who had abnormal results in screening test & those who had clinically suspicious lesions were sent for colposcopic evaluation (n= 442) & directed biopsy were taken from colposcopically suspected areas (n=214). The final diagnosis was based on histology. Results: Out of 5593 patients, 442 (7.20%) were VIA positive. 442 patients were colposcopically evaluated .Among them, 228 (51.58%) were normal and 202(45.70%) had different stages of cervical intraepithelial lesions (CIN) and 12 ( 2.71 % ) had carcinoma of cervix. Out of 214 patients biopsied, 23.36 % patients had a final diagnosis of CIN lesions, 5 (2.33%) had carcinoma in-situ & 17 cases (7.94%) had invasive carcinoma. Besides to find out the predictable factors of cervical lesions data have been collected from VIA positive patients regarding age of first coitus and first delivery, history of extra marital exposure and STI, use of contraceptive methods and family history of cancer. Age of first coitus between 12 to 15 years and 16 to 20 years were observed among 203 (46 %) and 40 % (177) women respectively. More than half of the patients (62%) were experienced with their first delivery within the age 15-20 years which was below 15 years of 12 % (53) patients. Fifty four percent patients used OCP and barrier methods used were only 10 %. Family history of cancer was observed among 09 % women. 58% patients were belonged to lower middle class and upper group were only 9% (table 1) Conclusion: In our study detection of different grades of intraepithelial lesions (CIN-I, CIN-II, CIN-III, invasive carcinoma) of cervix by VIA was comparable to that of colposcopy. So VIA is suitable for detection of precursor lesions of cervical cancer in low resource settings and also for diagnosis, follow up treatment and epidemiological studies of cervical cancer. Key words: Visual inspection; VIA; cervical carcinoma; colposcopy; screening; epidemiological studies. DOI: http://dx.doi.org/10.3329/bjms.v10i4.9494 BJMS 2011; 10 (4): 240-244