Sprague Dawley rats from different vendors vary in the modulation of prepulse inhibition of startle (PPI) by dopamine, acetylcholine, and glutamate drugs.

RATIONALE: Rodent vendors are often utilized interchangeably, assuming that the phenotype of a given strain remains standardized between colonies. Several studies, however, have found significant behavioral and physiological differences between Sprague Dawley (SD) rats from separate vendors. Prepulse inhibition of startle (PPI), a form of sensorimotor gating in which a low-intensity leading stimulus reduces the startle response to a subsequent stimulus, may also vary by vendor. Differences in PPI between rat strains are well known, but divergence between colonies within the SD strain lacks thorough examination. OBJECTIVES: We explored intrastrain variation in PPI by testing SD rats from two vendors: Envigo and Charles River (CR). METHODS: We selected drugs acting on four major neurotransmitter systems that have been repeatedly shown to modulate PPI: dopamine (apomorphine; 0.5, 1.5, 3.0 mg/kg), acetylcholine (scopolamine; 0.1, 0.5, 1.0 mg/kg), glutamate (dizocilpine; 0.5, 1.5, 2.5 mg/kg), and serotonin (2,5-Dimethoxy-4-iodoamphetamine, DOI; 0.25, 0.5, 1.0 mg/kg). We determined PPI and startle amplitude for each drug in male and female Envigo and CR SD rats. RESULTS: SD rats from Envigo showed dose-dependent decreases in PPI after apomorphine, scopolamine, or dizocilpine administration, without significant effects on startle amplitude. SD rats from CR were less sensitive to modulation of PPI and/or more sensitive to modulation of startle amplitude, across the three drugs. CONCLUSIONS: SD rats showed vendor differences in sensitivity to pharmacological modulation of PPI and startle. We encourage researchers to sample rats from separate vendors before experimentation to identify the most suited source of subjects for their specific endpoints.

Young-onset diabetes, nutritional therapy and novel insulin delivery systems: a report from the 21st Hong Kong Diabetes and Cardiovascular Risk Factors - East Meets West Symposium.

The prevalence and incidence of young-onset diabetes are increasing in many parts of the world, with the most rapid increase occurring in Asia, where one in five people with diabetes are diagnosed below the age of 40 years. Accumulation of glycaemic burden from an early age significantly increases the lifetime risks of developing complications from diabetes. Despite impending health threats, young people fare worse in the control of blood glucose and other metabolic risk factors. Challenges in the management of young-onset diabetes are compounded by heterogeneity of the underlying causes, pathophysiology and clinical phenotypes in this group. Effective characterization of people with diabetes has implications in steering the choice of glucose-lowering drugs, which, in turn, determines the clinical outcome. Medical nutritional therapy is key to effective management of people with diabetes but dietary adherence is often suboptimal among younger individuals. A recently published consensus report on nutritional therapy addresses dietary management in people with prediabetes as well as diabetes, and summarizes clinical evidence regarding macronutrient and micronutrient composition as well as eating patterns in people with diabetes. For people with type 1 diabetes, automated insulin delivery systems have rapidly evolved since the concept was first introduced at the National Institute of Health and the Juvenile Diabetes Research Foundation in 2005. The subsequent development of a type 1 diabetes simulator, developed using detailed human physiology data on carbohydrate metabolism replaced the need for pre-clinical animal studies and facilitated the seamless progression to artificial pancreas human clinical trials.

Tomatoes versus lycopene in oxidative stress and carcinogenesis: conclusions from clinical trials.

OBJECTIVE: To review the effects of tomato product supplementation, containing lycopene, on biomarkers of oxidative stress and carcinogenesis in human clinical trials. RESULTS: Supplementation of tomato products, containing lycopene, has been shown to lower biomarkers of oxidative stress and carcinogenesis in healthy and type II diabetic patients, and prostate cancer patients, respectively. Processed tomato products like tomato juice, tomato paste, tomato puree, tomato ketchup and tomato oleoresin have been shown to provide bioavailable sources of lycopene, with consequent increases in plasma lycopene levels versus baseline. Dietary fats enhance this process and should be consumed together with food sources of lycopene. The mechanisms of action involve protection of plasma lipoproteins, lymphocyte DNA and serum proteins against oxidative damage, and anticarcinogenic effects, including reduction of prostate-specific antigen, upregulation of connexin expression and overall decrease in prostate tumor aggressiveness. There is limited in vivo data on the health benefits of lycopene alone. Most of the clinical trials with tomato products suggest a synergistic action of lycopene with other nutrients, in lowering biomarkers of oxidative stress and carcinogenesis. CONCLUSIONS: Consumption of processed tomato products, containing lycopene, is of significant health benefit and can be attributed to a combination of naturally occurring nutrients in tomatoes. Lycopene, the main tomato carotenoid, contributes to this effect, but its role per se remains to be investigated.

Solution structure of the N-(deoxyguanosin-8-yl)-1-aminopyrene ([AP]dG) adduct opposite dA in a DNA duplex.

Solution structural studies have been undertaken on the aminopyrene-C(8)-dG ([AP]dG) adduct in the d(C5-[AP]G6-C7). d(G16-A17-G18) sequence context in an 11-mer duplex with dA opposite [AP]dG, using proton-proton distance and intensity restraints derived from NMR data in combination with distance-restrained molecular mechanics and intensity-restrained relaxation matrix refinement calculations. The exchangeable and nonexchangeable protons of the aminopyrene and the nucleic acid were assigned following analysis of two-dimensional NMR data sets on the [AP]dG.dA 11-mer duplex in H2O and D2O solution. The broadening of several resonances within the d(G16-A17-G18) segment positioned opposite the [AP]dG6 lesion site resulted in weaker NOEs, involving these protons in the adduct duplex. Both proton and carbon NMR data are consistent with a syn glycosidic torsion angle for the [AP]dG6 residue in the adduct duplex. The aminopyrene ring of [AP]dG6 is intercalated into the DNA helix between intact Watson-Crick dC5.dG18 and dC7.dG16 base pairs and is in contact with dC5, dC7, dG16, dA17, and dG18 residues that form a hydrophobic pocket around it. The intercalated AP ring of [AP]dG6 stacks over the purine ring of dG16 and, to a lesser extent dG18, while the looped out deoxyguanosine ring of [AP]dG6 stacks over dC5 in the solution structure of the adduct duplex. The dA17 base opposite the adduct site is not looped out of the helix but rather participates in an in-plane platform with adjacent dG18 in some of the refined structures of the adduct duplex. The solution structures are quite different for the [AP]dG.dA 11-mer duplex containing the larger aminopyrene ring (reported in this study) relative to the previously published [AF]dG.dA 11-mer duplex containing the smaller aminofluorene ring (Norman et al., Biochemistry 28, 7462-7476, 1989) in the same sequence context. Both the modified syn guanine and the dA positioned opposite it are stacked into the helix with the aminofluorene chromophore displaced into the minor groove in the latter adduct duplex. By contrast, the aminopyrenyl ring participates in an intercalated base-displaced structure in the present study of the [AP]dG.dA 11-mer duplex and in a previously published study of the [AP]dG.dC 11-mer duplex (Mao et al., Biochemistry 35, 12659-12670, 1996). Such intercalated base-displaced structures without hydrogen bonding between the [AP]dG adduct and dC or mismatched dA residues positioned opposite it, if present at a replication fork, may cause polymerase stalling and formation of a slipped intermediate that could produce frameshift mutations, the most dominant mutagenic consequence of the [AP]dG lesion.

Studies on the possible mechanism of the gastric mucosal protection by Calotropis procera--involvement of 5-lipoxygenase pathway.

The role of chloroform fraction of Calotropis procera root extract on different experimental ulcer models in rats was investigated. The extract demonstrated significant anti-ulcer activity against aspirin, indomethacin, ethanol, indomethacin + ethanol, or stress-induced ulcerations. Significant inhibition of gastric secretory volume and total acidity in pylorus ligated rats were observed to occur with the extract. It was also observed that the root extract significantly inhibited arachidonic acid metabolism induced by soyabean lipoxygenase. The results suggest that the anti-ulcer activity of the extract might be attributable to the inhibition of 5-lipoxygenase (5-LO).

Prospective randomized clinical trial to evaluate the optimal dose of 131 I for remnant ablation in patients with differentiated thyroid carcinoma.

BACKGROUND: Radioiodine has been used for more than a half-century to ablate thyroid remnants following thyroid surgery, but a single optimal dose has not been established. We designed a prospective randomized trial to determine the optimal dose of 131 I for remnant ablation. METHODS: Using a simple randomization technique, 149 patients with remnant thyroid were incorporated into 4 treatment groups. Twenty-seven of these patients were administered 25 to 34 millicurie (mCi) of 131 I (30 +/- 1.5), 54 received 35 to 64 mCi (50.6 +/- 5.4), 38 received 65 to 119 mCi (88.6 +/- 14) and 30 patients received 120 to 200 mCi (155 +/- 28.7). Six months to 1 year after treatment, all subjects were reassessed after withdrawing L-thyroxine for 4 to 6 weeks. A successful ablation was defined as the absence of thyroid bed activity in 5 mCi 131 I neck scan at 48 hours along with 2 adjunctive criteria which were the neck uptake of <0.2% of the administered activity and the thyroglobulin (Tg) value of <10 ng/mL. RESULTS: Applying the above criteria, we observed complete ablation of 17 of 27 thyroid gland remnants (63%) in the 30 mCi group, 42 of 54 (77.8%) in the 50 mCi group, 28 of 38 (73.7%) in the 90 mCi group and 23 of 30 (76.7%) in the 155 mCi group. When the radiation-absorbed dose was calculated, a 30 mCi dose delivered approximately 20,000 centigray (cGy), a 50 mCi dose about 30,000 cGy, a 90 mCi dose about 50,000 cGy, and a 155 mCi dose about 130,000 cGy. CONCLUSIONS: Increasing the empirical 131 I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high dose remnant ablation needs critical evaluation. Based on dosimetry results, one should aim to deliver about 30,000 cGy to the thyroid remnant, as higher doses do not appear to yield a higher ablation rate.

Identification of a stable RNA encoded by the H-strand of the mouse mitochondrial D-loop region and a conserved sequence motif immediately upstream of its polyadenylation site.

By using a combination of Northern blot hybridization with strand-specific DNA probes, S1 nuclease protection, and sequencing of oligo-dT-primed cDNA clones, we have identified a 0.8 kb poly(A)-containing RNA encoded by the H-strand of the mouse mitochondrial D-loop region. The 5' end of the RNA maps to nucleotide 15417, a region complementary to the start of tRNA(Pro) gene and the 3' polyadenylated end maps to nucleotide 16295 of the genome, immediately upstream of tRNA(Phe) gene. The H-strand D-loop region encoded transcripts of similar size are also detected in other vertebrate systems. In the mouse, rat, and human systems, the 3' ends of the D-loop encoded RNA are preceded by conserved sequences AAUAAA, AAUUAA, or AACUAA, that resemble the polyadenylation signal. The steady-state level of the RNA is generally low in dividing or in vitro cultured cells, and markedly higher in differentiated tissues like liver, kidney, heart, and brain. Furthermore, an over 10-fold increase in the level of this RNA is observed during the induced differentiation of C2C12 mouse myoblast cells into myotubes. These results suggest that the D-loop H-strand encoded RNA may have yet unknown biological functions. A 20 base pair DNA sequence from the 3' terminal region containing the conserved sequence motif binds to a protein from the mitochondrial extracts in a sequence-specific manner. The binding specificity of this protein is distinctly different from the previously characterized H-strand DNA termination sequence in the D-loop or the H-strand transcription terminator immediately downstream of the 16S rRNA gene. Thus, we have characterized a novel poly(A)-containing RNA encoded by the H-strand of the mitochondrial D-loop region and also identified the putative ultimate termination site for the H-strand transcription.

Preliminary studies on the antiinflammatory and analgesic activities of Calotropis procera root extract.

A chloroform-soluble fraction from Calotropis procera roots showed significant dose-related antiinflammatory activity in rats using the pharmacologic models of carrageenin-induced pedal oedema, cotton pellet granuloma and formaldehyde-induced arthritis. In addition, significant analgesic potential was demonstrated using acetic acid-induced writhing in mice.

Mode of action of iron on arylsulphatases under acute lead acetate treated conditions in rats.

Arylsulphatases A, B and C were found to be inhibited in liver and kidney tissues under lead acetate-treated conditions (both in vivo and in vitro) in rats. When lead acetate-treated animals (in vivo) were supplemented with ferric ammonium citrate (in vivo), a remarkable recovery was found in the activities of all arylsulphatases A, B and C whereas ferric ammonium citrate itself had no effect on the activities of arylsulphatases. When both the in vivo and in vitro lead acetate-treated arylsulphatases were supplemented with the purified ferritins (in vitro) it was observed that lead-induced inhibition of the activities of arylsulphatases was successfully reversed. It was also found that ferritins were able to bind a large quantity of lead. These results indicated that ferritins were directly involved for reactivation of arylsulphatases which were inhibited by lead. It was well established that a response to iron administration in rats was an immediate de novo stimulation of ferritin biosynthesis. Iron might therefore protect the enzymatic activities of arylsulphatases by enhancing the level of ferritin in liver and kidney tissues which is known to bind a large quantity of lead thereby ameliorating their toxic effects in the living system.

Substrate binding domain of murine leukemia virus reverse transcriptase. Identification of lysine 103 and lysine 421 as binding site residues.

The substrate deoxynucleoside triphosphate (dNTP) binding site of Moloney murine leukemia virus (M-MuLV) reverse transcriptase was labeled with pyridoxal 5'-phosphate (PLP), a substrate binding site-directed reagent for DNA polymerases (Modak, M. J. (1976) Biochemistry 15, 3620-3626). Treatment of M-MuLV reverse transcriptase with PLP results in the loss of RNA-dependent DNA polymerase activity, but has no effect on ribonuclease H activity. Neither template-primer nor substrate dNTP alone shows any protective effect from PLP-mediated inactivation. However, the presence of both template-primer and complementary substrate dNTP significantly protects M-MuLV reverse transcriptase from PLP inhibition. Using tritiated sodium borohydride to label the pyridoxylated enzyme, approximately 4 mol of PLP were incorporated per mol of enzyme. In the presence of template-primer and the complementary dNTP, however, only 2 mol of PLP were incorporated. Comparative tryptic peptide mapping of enzyme, modified in the presence and absence of substrates by PLP reaction on C-18 reverse phase columns, indicated the protection of two peptides from pyridoxylation in the presence of substrate triphosphate. These two peptides were further purified and characterized by amino acid analyses and sequencing and were found to span residues 103 to 110 and 412 to 425 in the primary amino acid sequence of M-MuLV reverse transcriptase. Furthermore, Lys-103 of peptide I and Lys-421 of peptide II were found to be the targets of pyridoxylation, indicating that these 2 lysine residues are involved in substrate dNTP binding in M-MuLV reverse transcriptase.

Effects of mercuric chloride on several scavenging enzymes in rat kidney and influence of vitamin E supplementation.

Administration of HgCl2 at a dose of 5 mg/kg body weight/day for 15 days to male albino rats brought about a marked depression of the scavenging enzymes viz. glutathione peroxidase and glutathione S-transferase, in kidney. There was an adaptive rise in the levels of catalase and no increased lipid peroxidation was observed. The levels of both glutathione and glutathione reductase were decreased, whereas total thiol increased. In the intoxicated rats, Vitamin-E was effective in bringing back glutathione levels to normal. The adaptation in this group of animals is reflected by increased superoxide dismutase activities. Feeding of Vitamin-E alone could cause a depression of the scavenging enzymes like glutathione peroxidase and glutathione S-transferase along with a slight lowering of glutathione levels.